WorldWideScience

Sample records for abscisic acid responses

  1. Response of barley aleurone layers to abscisic acid

    Energy Technology Data Exchange (ETDEWEB)

    Ho, D.T.H.; Varner, J.E.

    1976-02-01

    Cordycepin, an inhibitor of RNA synthesis in barley (Hordeum vulgare L.) aleurone cells, does not inhibit the gibberellic acid-enhanced ..cap alpha..-amylase (EC 3.2.1.1.) synthesis in barley aleurone layers if it is added 12 hours or more after the addition of the hormone. However, the accumulation of ..cap alpha..-amylase activity after 12 hours of gibberellic acid can be decreased by abscisic acid. The accumulation of ..cap alpha..-amylase activity is sustained or quickly restored when cordycepin is added simultaneously or some time after abscisic acid, indicating that the response of aleurone layers to abscisic acid depends on the continuous synthesis of a short lived RNA. By analysis of the newly synthesized proteins by gel electrophoresis with sodium dodecylsulfate, it was observed that the synthesis of ..cap alpha..-amylase is decreased in the presence of abscisic acid while the synthesis of most of the other proteins remains unchanged. From the rate of resumption of ..cap alpha..-amylase production in the presence of cordycepin and abscisic acid, it appears that abscisic acid does not have a measurable effect on the stability of ..cap alpha..-amylase mRNA.

  2. Arabidopsis YAK1 regulates abscisic acid response and drought resistance

    KAUST Repository

    Kim, Dongjin

    2016-06-06

    Abscisic acid (ABA) is an important phytohormone that controls several plant processes such as seed germination, seedling growth, and abiotic stress response. Here, we report that AtYak1 plays an important role in ABA signaling and postgermination growth in Arabidopsis. AtYak1 knockout mutant plants were hyposensitive to ABA inhibition of seed germination, cotyledon greening, seedling growth, and stomatal movement. atyak1-1 mutant plants display reduced drought stress resistance, as evidenced by water loss rate and survival rate. Molecular genetic analysis revealed that AtYak1 deficiency led to elevated expression of stomatal-related gene, MYB60, and down-regulation of several stress-responsive genes. Altogether, these results indicate that AtYak1 plays a role as a positive regulator in ABA-mediated drought response in Arabidopsis. © 2016 Federation of European Biochemical Societies.

  3. Transcriptional Responses to Gibberellin and Abscisic Acid in Barley Aleurone

    Institute of Scientific and Technical Information of China (English)

    Kegui Chen; Yong-Qiang Charles An

    2006-01-01

    Cereal aleurone has been established as a model system to investigate giberrellin (GA) and abscisic acid (ABA) responses. Using Barley 1 GeneChip, we examined the mRNA accumulation of over 22 000 genes in de-embryonated barley aleurone treated with GA and ABA. We observed that 1328 genes had more than a threefold change in response to GA treatment, whereas 206 genes had a more than threefold change in response to ABA treatment. Interestingly, approximately 2.5-fold more genes were up-regulated than downregulated by ABA. Eighty-three genes were differentially regulated by both GA and ABA. Most of the genes were subject to antagonistic regulation by ABA and GA, particularly for genes related to seed maturation and germination, such as genes encoding late embryogenesis abundant proteins and storage mobilization enzymes. This supports the antagonistic roles of GA and ABA in seed maturation and seed germination.Interestingly, we observed that a significant percentage of the genes were coordinately regulated by both GA and ABA. Some GA-responsive genes encoded proteins involved in ethylene, jasmonate, brassinosteroid and auxin metabolic and signaling transduction pathways, suggesting their potential interaction with the GA response. We also identified a group of transcription factor genes, such as MYB and Homeobox genes, that were differentially regulated by GA. In addition, a number of GA- and/or ABA-responsive genes encoded components potentially involved in GA and ABA signal transduction pathway. Overall, the present study provides a comprehensive and global view of transcript expression accompanying the GA and ABA response in barley aleurone and identifies a group of genes with potential regulatory functions in GA- and ABA-signaling pathways for future functional validation.

  4. Microarray Analysis of Transcriptional Responses to Abscisic Acid and Salt Stress in Arabidopsis thaliana

    Directory of Open Access Journals (Sweden)

    Yucheng Wang

    2013-05-01

    Full Text Available Abscisic acid (ABA plays a crucial role in plant responses to abiotic stress. To investigate differences in plant responses to salt and ABA stimulus, differences in gene expression in Arabidopsis in response to salt and ABA were compared using an Agilent oligo microarray. A total of 144 and 139 genes were significantly up- and downregulated, respectively, under NaCl stress, while 406 and 381 genes were significantly up- and downregulated, respectively, under ABA stress conditions. In addition, 31 genes were upregulated by both NaCl and ABA stresses, and 23 genes were downregulated by these stressors, suggesting that these genes may play similar roles in plant responses to salt and ABA stress. Gene ontology (GO analysis revealed four subgroups of genes, including genes in the GO categories “Molecular transducer activity”, “Growth”, “Biological adhesion” and “Pigmentation”, which were expressed in response to ABA stress but not NaCl stress. In addition, genes that play specific roles during salt or ABA stress were identified. Our results may help elucidate differences in the response of plants to salt and ABA stress.

  5. Abscisic Acid-mediated Epigenetic Processes in Plant Development and Stress Responses

    Institute of Scientific and Technical Information of China (English)

    Viswanathan Chinnusamy; Zhizhong Gong; Jian-Kang Zhu

    2008-01-01

    Abscisic acid (ABA) regulates diverse plant processes, growth and development under non-stress conditions and plays a pivotal role in abiotic stress tolerance. Although ABA-regulated genetic processes are well known, recent discoveries reveal that epigenetic processes are an integral part of ABA-regulated processes. Epigenetic mechanisms, namely, histone modifications and cytosine DNA methylation-induced modification of genome give rise to epigenomes, which add diversity and complexity to the genome of organisms. Histone monoubiquitination appears to regulate ABA levels in developing seeds through histone H2B monoubiquitination. ABA and H2B ubiquitination dependent chromatin remodeling regulate seed dormancy. Transcription factor networks necessary for seed maturation are repressed by histone deacetylases (HDACs)-dependent and PICKLE chromatin remodeling complexes (CRCs), whereas ABA induces the expression of these genes directly or through repression of HDACs. Abiotic stress-induced ABA regulates stomatal response and stress-responsive gene expression through HDACs and HOS15-dependent histone deacetylation, as well as through the ATP-dependent SWITCH/SUCROSE NONFERMENTING CRC. ABA also probably regulates the abiotic stress response through DNA methylation and short interfering RNA pathways. Further studies on ABA-regulated spigenome will be of immense use to understand the plant development, stress adaptation and stress memory.

  6. Prediction and Validation of Promoters Involved in the Abscisic Acid Response in Physcomitrella patens

    Institute of Scientific and Technical Information of China (English)

    Gerrit Timmerhaus; Sebastian T.Hanke; Karl Buchta; Stefan A. Rensing

    2011-01-01

    Detection of cis-regulatory elements, such as transcription factor binding sites (TFBS), through utilization of ortholog conservation is possible only if genomic data from closely related organisms are available. An alternative ap-proach is the detection of TFBS based on their overrepresentation in promoters of co-regulated genes. However, this ap-proach usually suffers from a high rate of false-positive prediction. Here, we have conducted a case study using promoters of genes known to be strongly induced by the phytohormone abscisic acid (ABA)in the model plant Physcornitrella patens,a moss. Putative TFBS were detected using three de novo motif detection tools in a strict consensus approach. The resulting motifs were validated using data from microarray expression profiling and were able to predict ABA-induced genes with high specificity (90.48%)at mediocre sensitivity (33.33%). In addition, 27 genes predicted to contain ABA-responsive TFBS were validated using real-time PCR. Here, a total of 37% of the genes could be shown to be induced upon ABA treatment,while 70% were found to be regulated by ABA. We conclude that the consensus approach for motif detection using co-regulation information can be used to identify genes that are regulated under a given stimulus. In terms of evolution, we find that the ABA response has apparently been conserved since the first land plants on the level of families involved in transcriptional regulation.

  7. Stomatal response of an anisohydric grapevine cultivar to evaporative demand, available soil moisture and abscisic acid.

    Science.gov (United States)

    Rogiers, Suzy Y; Greer, Dennis H; Hatfield, Jo M; Hutton, Ron J; Clarke, Simon J; Hutchinson, Paul A; Somers, Anthony

    2012-03-01

    Stomatal responsiveness to evaporative demand (air vapour pressure deficit (VPD)) ranges widely between species and cultivars, and mechanisms for stomatal control in response to VPD remain obscure. The interaction of irrigation and soil moisture with VPD on stomatal conductance is particularly difficult to predict, but nevertheless is critical to instantaneous transpiration and vulnerability to desiccation. Stomatal sensitivity to VPD and soil moisture was investigated in Semillon, an anisohydric Vitis vinifera L. variety whose leaf water potential (Ψ(l)) is frequently lower than that of other grapevine varieties grown under similar conditions in the warm grape-growing regions of Australia. A survey of Semillon vines across seven vineyards revealed that, regardless of irrigation treatment, midday Ψ(l) was dependent on not only soil moisture but VPD at the time of measurement. Predawn Ψ(l) was more closely correlated to not only soil moisture in dry vineyards but to night-time VPD in drip-irrigated vineyards, with incomplete rehydration during high night-time VPD. Daytime stomatal conductance was low only under severe plant water deficits, induced by extremes in dry soil. Stomatal response to VPD was inconsistent across irrigation regime; however, in an unirrigated vineyard, stomatal sensitivity to VPD-the magnitude of stomatal response to VPD-was heightened under dry soils. It was also found that stomatal sensitivity was proportional to the magnitude of stomatal conductance at a reference VPD of 1kPa. Exogenous abscisic acid (ABA) applied to roots of Semillon vines growing in a hydroponic system induced stomatal closure and, in field vines, petiole xylem sap ABA concentrations rose throughout the morning and were higher in vines with low Ψ(l). These data indicate that despite high stomatal conductance of this anisohydric variety when grown in medium to high soil moisture, increased concentrations of ABA as a result of very limited soil moisture may augment

  8. The Pepper CaOSR1 Protein Regulates the Osmotic Stress Response via Abscisic Acid Signaling.

    Science.gov (United States)

    Park, Chanmi; Lim, Chae Woo; Lee, Sung Chul

    2016-01-01

    Plants are sessile organisms, and their growth and development is detrimentally affected by environmental stresses such as drought and high salinity. Defense mechanisms are tightly regulated and complex processes, which respond to changing environmental conditions; however, the precise mechanisms that function under adverse conditions remain unclear. Here, we report the identification and functional characterization of the CaOSR1 gene, which functions in the adaptive response to abiotic stress. We found that CaOSR1 gene expression in pepper leaves was up-regulated after exposure to abscisic acid (ABA), drought, and high salinity. In addition, we demonstrated that the fusion protein of CaOSR1 with green fluorescent protein (GFP) is localized in the nucleus. We used CaOSR1-silenced pepper plants and CaOSR1-OX-overexpressing (OX) transgenic Arabidopsis plants to show that the CaOSR1 protein regulates the osmotic stress response. CaOSR1-silenced pepper plants showed increased drought susceptibility, and this was accompanied by a high transpiration rate. CaOSR1-OX plants displayed phenotypes that were hypersensitive to ABA and hyposensitive to osmotic stress, during the seed germination and seedling growth stages; furthermore, these plants exhibited enhanced drought tolerance at the adult stage, and this was characterized by higher leaf temperatures and smaller stomatal apertures because of ABA hypersensitivity. Taken together, our data indicate that CaOSR1 positively regulates osmotic stress tolerance via ABA-mediated cell signaling. These findings suggest an involvement of a novel protein in ABA and osmotic stress signalings in plants.

  9. GID1 modulates stomatal response and submergence tolerance involving abscisic acid and gibberellic acid signaling in rice.

    Science.gov (United States)

    Du, Hao; Chang, Yu; Huang, Fei; Xiong, Lizhong

    2015-11-01

    Plant responses to abiotic stresses are coordinated by arrays of growth and developmental programs. Gibberellic acid (GA) and abscisic acid (ABA) play critical roles in the developmental programs and environmental responses, respectively, through complex signaling and metabolism networks. However, crosstalk between the two phytohormones in stress responses remains largely unknown. In this study, we report that GIBBERELLIN-INSENSITIVE DWARF 1 (GID1), a soluble receptor for GA, regulates stomatal development and patterning in rice (Oryza sativa L.). The gid1 mutant showed impaired biosynthesis of endogenous ABA under drought stress conditions, but it exhibited enhanced sensitivity to exogenous ABA. Scanning electron microscope and infrared thermal image analysis indicated an increase in the stomatal conductance in the gid1 mutant under drought conditions. Interestingly, the gid1 mutant had increased levels of chlorophyll and carbohydrates under submergence conditions, and showed enhanced reactive oxygen species (ROS)-scavenging ability and submergence tolerance compared with the wild-type. Further analyses suggested that the function of GID1 in submergence responses is partially dependent on ABA, and GA signaling by GID1 is involved in submergence tolerance by modulating carbohydrate consumption. Taken together, these findings suggest GID1 plays distinct roles in stomatal response and submergence tolerance through both the ABA and GA signaling pathways in rice.

  10. Arabidopsis cysteine-rich receptor-like kinase 45 functions in the responses to abscisic acid and abiotic stresses

    KAUST Repository

    Zhang, Xiujuan

    2013-06-01

    The phytohormone abscisic acid (ABA) regulates seed germination, plant growth and development, and response to abiotic stresses such as drought and salt stresses. Receptor-like kinases are well known signaling components that mediate plant responses to developmental and environmental stimuli. Here, we characterized the biological function of an ABA and stress-inducible cysteine-rich receptor-like protein kinase, CRK45, in ABA signaling in Arabidopsis thaliana. The crk45 mutant was less sensitive to ABA than the wild type during seed germination and early seedling development, whereas CRK45 overexpression plants were more sensitive to ABA compared to the wild type. Furthermore, overexpression of CRK45 led to hypersensitivity to salt and glucose inhibition of seed germination, whereas the crk45 mutant showed the opposite phenotypes. In addition, CRK45 overexpression plants had enhanced tolerance to drought. Gene expression analyses revealed that the expression of representative stress-responsive genes was significantly enhanced in CRK45 overexpression plants in response to salt stress. ABA biosynthetic genes such as NCED3,. 22NCED3, 9-Cis-Epoxycarotenoid Dioxygenase 3.NCED5,. 33NCED5, 9-Cis-Epoxycarotenoid Dioxygenase 5.ABA2,. 44ABA2, Abscisic Acid Deficient 2. and AAO355AAO3, Abscisic Aldehyde Oxidase 3. were also constitutively elevated in the CRK45 overexpression plants. We concluded that CRK45 plays an important role in ABA signaling that regulates Arabidopsis seeds germination, early seedling development and abiotic stresses response, by positively regulating ABA responses in these processes. © 2013 Elsevier Masson SAS.

  11. GIGANTEA enables drought escape response via abscisic acid-dependent activation of the florigens and SUPPRESSOR OF OVEREXPRESSION OF CONSTANS.

    Science.gov (United States)

    Riboni, Matteo; Galbiati, Massimo; Tonelli, Chiara; Conti, Lucio

    2013-07-01

    Modulation of the transition to flowering plays an important role in the adaptation to drought. The drought-escape (DE) response allows plants to adaptively shorten their life cycle to make seeds before severe stress leads to death. However, the molecular basis of the DE response is unknown. A screen of different Arabidopsis (Arabidopsis thaliana) flowering time mutants under DE-triggering conditions revealed the central role of the flower-promoting gene GIGANTEA (GI) and the florigen genes FLOWERING LOCUS T (FT) and TWIN SISTER OF FT (TSF) in the DE response. Further screens showed that the phytohormone abscisic acid is required for the DE response, positively regulating flowering under long-day conditions. Drought stress promotes the transcriptional up-regulation of the florigens in an abscisic acid- and photoperiod-dependent manner, so that early flowering only occurs under long days. Along with the florigens, the floral integrator SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1 is also up-regulated in a similar fashion and contributes to the activation of TSF. The DE response was recovered under short days in the absence of the floral repressor SHORT VEGETATIVE PHASE or in GI-overexpressing plants. Our data reveal a key role for GI in connecting photoperiodic cues and environmental stress independently from the central FT/TSF activator CONSTANS. This mechanism explains how environmental cues may act upon the florigen genes in a photoperiodically controlled manner, thus enabling plastic flowering responses.

  12. [The ABC of abscisic acid action in plant drought stress responses].

    Science.gov (United States)

    Leung, Jeffrey; Valon, Christiane; Moreau, Bertrand; Boeglin, Martin; Lefoulon, Cécile; Joshi-Saha, Archana; Chérel, Isabelle

    2012-01-01

    The combined daily consumption of fresh water ranges from 200 to 700 liters per capita per day in most developed countries, with about 70% being used for agricultural needs. Unlike other resources such as the different forms of energy, water has no other alternatives. With the looming prospect of global water crisis, the recent laudable success in deciphering the early steps in the signal transduction of the "stress hormone" abscisic acid (ABA) has ignited hopes that crops can be engineered with the capacity to maintain productivity while requiring less water input. Although ABA was first discovered in plants, it has resurfaced in the human brain (and many other non-plant organisms : sea sponge, some parasites, hydra to name a few), suggesting that its existence may be widespread. In humans, more amazingly, ABA has shown anti-inflammatory and antiviral properties. Even its receptors and key signaling intermediates have homologs in the human genome suggesting that evolution has re-fashioned these same proteins into new functional contexts. Thus, learning about the molecular mechanisms of ABA in action using the more flexible plant model will be likely beneficial to other organisms, and especially in human diseases, which is topical in the medical circle. ABA can accumulate up to 10 to 30-fold in plants under drought stress relative to unstressed conditions. The built up of the hormone then triggers diverse adaptive pathways permitting plants to withstand temporary bouts of water shortage. One favorite experimental model to unravel ABA signaling mechanisms in all of its intimate detail is based on the hormone's ability to elicit stomatal closure - a rapid cellular response of land plants to limit water loss through transpiration. Each microscopic stoma, or pore, is contoured by two specialized kidney-shaped cells called the guard cells. Because land plants are protected by a waxy cuticle impermeable to gas exchange, the stomatal pores are thus the primary portals for

  13. Growth, Gas Exchange, Abscisic Acid, and Calmodulin Response to Salt Stress in Three Poplars

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    In the present study, we investigated the effects of increasing salinity on growth, gas exchange, abscisic acid(ABA), calmodulin (CAM), and the relevance to salt tolerance in seedlings of Populus euphratica Oliv. and cuttings of P. "pupularis 35-44" (P. popularis) and P. x euramericana cv. 1-214 (P. cv. Italica). The relative growth rates of shoot height (RGRH) for P. cv. Italica and P. popularis were severely reduced by increasing salt stress,whereas the growth reduction was relatively less in P. euphratica. Similarly, P. euphratica maintained higher net photosynthetic rates (Pn) and unit transpiration rates (TRN) than P. cv. Italica and P. popularis under conditions of higher salinity. Salinity caused a significant increase in leaf ABA and CaM in the three genotypes after the onset of stress, but NaCl-induced ABA and CaM accumulation was more pronounced in P. euphratica,suggesting that P. euphratica plants are more sensitive in sensing soil salinity than the other two poplars.Furthermore, P. euphratica maintained relatively higher ABA and CaM concentrations under conditions of high salinity. The higher capacity to synthesize stress signals, namely ABA and CaM, in P. euphratica and the contribution of this to the salt resistance of P. euphratica are discussed.

  14. Jasmonic acid interacts with abscisic acid to regulate plant responses to water stress conditions

    Science.gov (United States)

    de Ollas, Carlos; Arbona, Vicent; Gómez-Cadenas, Aurelio

    2015-01-01

    Phytohormones are key players in signaling environmental stress conditions. Hormone profiling together with proline accumulation were studied in leaves and roots of different mutant lines of Arabidopsis. Regulation of proline accumulation in this system seems complex and JA-deficient (jar1-1) and JA-insensitive (jai1) lines accumulating high levels of proline despite their very low ABA levels seems to discard an ABA-dependent response. However, the pattern of proline accumulation in jai1 seedlings parallels that of ABA. Under stress conditions, there is an opposite pattern of ABA accumulation in roots of jar1-1/coi1-16 (in which ABA only slightly increase) and jai1 (in which ABA increase is even higher than in WT plants). This also makes JA-ABA crosstalk complex and discards any lineal pathway that could explain this hormonal interaction. PMID:26340066

  15. The small ethylene response factor ERF96 is involved in the regulation of the abscisic acid response in Arabidopsis

    Directory of Open Access Journals (Sweden)

    Xiaoping eWang

    2015-11-01

    Full Text Available Ethylene regulates many aspects of plant growth and development including seed germination, leaf senescence, and fruit ripening, and of plant responses to environmental stimuli including both biotic and abiotic stresses. Ethylene Response Factors (ERFs are plant-specific transcription factors and are a subfamily of the AP2 (APETALA2/ERF transcription factor family. The function of many members in this large gene family remains largely unknown. ERF96, a member of the Group IX ERF family transcription factors, has recently been shown to be a transcriptional activator that is involved in plant defense response in Arabidopsis. Here we provide evidence that ERF96 is a positive regulator of abscisic acid (ABA responses. Bioinformatics analysis indicated that there are a total four small ERFs in Arabidopsis including ERF95, ERF96, ERF97 and ERF98, and that ERF96 forms a cluster with ERF95 and ERF97. By using quantitative RT-PCR, we found that ERF96 is expressed in all tissues and organs examined except roots, with relatively high expression in flowers and seeds. Results from the protoplast transfection assay results indicated that the EDLL motif-containing C-terminal domain is responsible for ERF96’s transcriptional activity. Although loss-of-function mutant of ERF96 was morphologically similar to wild type plants, transgenic plants overexpressing ERF96 had smaller rosette size and were delayed in flowering time. In ABA sensitivity assays, we found that ERF96 overexpression plants were hypersensitive to ABA in terms of ABA inhibition of seed germination, early seedling development and root elongation. Consistent with these observations, elevated transcript levels of some ABA-responsive genes including RD29A, ABI5, ABF3, ABF4, P5CS and COR15A were observed in the transgenic plants in the presence of ABA. However, in the absence of ABA treatment, the transcript levels of these ABA-responsive genes remained largely unchanged. Our experiments also showed

  16. Anion-Channel Blockers Inhibit S-Type Anion Channels and Abscisic Acid Responses in Guard Cells.

    Science.gov (United States)

    Schwartz, A.; Ilan, N.; Schwarz, M.; Scheaffer, J.; Assmann, S. M.; Schroeder, J. I.

    1995-10-01

    The effects of anion-channel blockers on light-mediated stomatal opening, on the potassium dependence of stomatal opening, on stomatal responses to abscisic acid (ABA), and on current through slow anion channels in the plasma membrane of guard cells were investigated. The anion-channel blockers anthracene-9-carboxylic acid (9-AC) and niflumic acid blocked current through slow anion channels of Vicia faba L. guard cells. Both 9-AC and niflumic acid reversed ABA inhibition of stomatal opening in V. faba L. and Commelina communis L. The anion-channel blocker probenecid also abolished ABA inhibition of stomatal opening in both species. Additional tests of 9-AC effects on stomatal aperture in Commelina revealed that application of this anion-channel blocker allowed wide stomatal opening under low (1 mM) KCI conditions and increased the rate of stomatal opening under both low and high (100 mM) KCI conditions. These results indicate that anion channels can function as a negative regulator of stomatal opening, presumably by allowing anion efflux and depolarization, which prohibits ion up-take in guard cells. Furthermore, 9-AC prevented ABA induction of stomatal closure. A model in which ABA activation of anion channels contributes a rate-limiting mechanism during ABA-induced stomatal closure and inhibition of stomatal opening is discussed.

  17. Ethylene responses in rice roots and coleoptiles are differentially regulated by a carotenoid isomerase-mediated abscisic acid pathway.

    Science.gov (United States)

    Yin, Cui-Cui; Ma, Biao; Collinge, Derek Phillip; Pogson, Barry James; He, Si-Jie; Xiong, Qing; Duan, Kai-Xuan; Chen, Hui; Yang, Chao; Lu, Xiang; Wang, Yi-Qin; Zhang, Wan-Ke; Chu, Cheng-Cai; Sun, Xiao-Hong; Fang, Shuang; Chu, Jin-Fang; Lu, Tie-Gang; Chen, Shou-Yi; Zhang, Jin-Song

    2015-04-01

    Ethylene and abscisic acid (ABA) act synergistically or antagonistically to regulate plant growth and development. ABA is derived from the carotenoid biosynthesis pathway. Here, we analyzed the interplay among ethylene, carotenoid biogenesis, and ABA in rice (Oryza sativa) using the rice ethylene response mutant mhz5, which displays a reduced ethylene response in roots but an enhanced ethylene response in coleoptiles. We found that MHZ5 encodes a carotenoid isomerase and that the mutation in mhz5 blocks carotenoid biosynthesis, reduces ABA accumulation, and promotes ethylene production in etiolated seedlings. ABA can largely rescue the ethylene response of the mhz5 mutant. Ethylene induces MHZ5 expression, the production of neoxanthin, an ABA biosynthesis precursor, and ABA accumulation in roots. MHZ5 overexpression results in enhanced ethylene sensitivity in roots and reduced ethylene sensitivity in coleoptiles. Mutation or overexpression of MHZ5 also alters the expression of ethylene-responsive genes. Genetic studies revealed that the MHZ5-mediated ABA pathway acts downstream of ethylene signaling to inhibit root growth. The MHZ5-mediated ABA pathway likely acts upstream but negatively regulates ethylene signaling to control coleoptile growth. Our study reveals novel interactions among ethylene, carotenogenesis, and ABA and provides insight into improvements in agronomic traits and adaptive growth through the manipulation of these pathways in rice.

  18. Abscisic acid signals reorientation of polyamine metabolism to orchestrate stress responses via the polyamine exodus pathway in grapevine.

    Science.gov (United States)

    Toumi, Imene; Moschou, Panagiotis N; Paschalidis, Konstantinos A; Bouamama, Badra; Ben Salem-Fnayou, Asma; Ghorbel, Abdel Wahed; Mliki, Ahmed; Roubelakis-Angelakis, Kalliopi A

    2010-05-01

    Polyamines (PAs) have been suggested to be implicated in plant responses to abiotic and biotic stress. Grapevine is a model perennial plant species whose cultivars respond differently to osmotic stress. In this study, we used two cultivars, one sensitive (S) and one tolerant (T) to drought. In adult vines subjected to drought under greenhouse conditions, total PAs were significantly lower in the control T- and higher in the control S-genotype and significantly increased or decreased, respectively, post-treatment. Soluble Put and Spd exhibited the greatest increase on d 8 post-treatment in the T- but not in the S-genotype, which accumulated soluble Spm. Abscisic acid (ABA) was differentially accumulated in T- and S-genotypes under drought conditions, and activated the PA biosynthetic pathway, which in turn was correlated with the differential increases in PA titers. In parallel, polyamine oxidases (PAOs) increased primarily in the S-genotype. ABA at least partially induced PA accumulation and exodus into the apoplast, where they were oxidized by the apoplastic amine oxidases (AOs), producing H2O2, which signaled secondary stress responses. The results here show that the ABA signaling pathway integrates PAs and AOs to regulate the generation of H2O2, which signals further stress responses or the PCD syndrome.

  19. Expression of the betaine aldehyde dehydrogenase gene in barley in response to osmotic stress and abscisic acid.

    Science.gov (United States)

    Ishitani, M; Nakamura, T; Han, S Y; Takabe, T

    1995-01-01

    When subjected to salt stress or drought, some vascular plants such as barley respond with an increased accumulation of the osmoprotectant glycine betaine (betaine), being the last step of betaine synthesis catalyzed by betaine aldehyde dehydrogenase (BADH). We report here cloning and characterization of BADH cDNA from barley, a monocot, and the expression pattern of a BADH transcript. An open reading frame of 1515 bp encoded a protein which showed high homology to BADH enzymes present in other plants (spinach and sugar-beet) and in Escherichia coli. Transgenic tobacco plants harboring the clone expressed high levels of both BADH protein and its enzymatic activity. Northern blot analyses indicated that BADH mRNA levels increased almost 8-fold and 2-fold, respectively, in leaves and roots of barley plants grown in high-salt conditions, and that these levels decreased upon release of the stress, whereas they did not decrease under continuous salt stress. BADH transcripts also accumulate in response to water stress or drought, indicating a common response of the plant to osmotic changes that affect its water status. The addition of abscisic acid (ABA) to plants during growth also increased the levels of BADH transcripts dramatically, although the response was delayed when compared to that found for salt-stressed plants. Removal of plant roots before transferring the plants to high-salt conditions reduced only slightly the accumulation of BADH transcripts in the leaves.

  20. The avoidance and aggregative movements of mesophyll chloroplasts in C(4) monocots in response to blue light and abscisic acid.

    Science.gov (United States)

    Maai, Eri; Shimada, Shouu; Yamada, Masahiro; Sugiyama, Tatsuo; Miyake, Hiroshi; Taniguchi, Mitsutaka

    2011-05-01

    In C(4) plants, mesophyll (M) chloroplasts are randomly distributed along the cell walls, whereas bundle sheath chloroplasts are located in either a centripetal or centrifugal position. It was reported previously that only M chloroplasts aggregatively redistribute to the bundle sheath side in response to extremely strong light or environmental stresses. The aggregative movement of M chloroplasts is also induced in a light-dependent fashion upon incubation with abscisic acid (ABA). The involvement of reactive oxygen species (ROS) and red/blue light in the aggregative movement of M chloroplasts are examined here in two distinct subtypes of C(4) plants, finger millet and maize. Exogenously applied hydrogen peroxide or ROS scavengers could not change the response patterns of M chloroplast movement to light and ABA. Blue light irradiation essentially induced the rearrangement of M chloroplasts along the sides of anticlinal walls, parallel to the direction of the incident light, which is analogous to the avoidance movement of C(3) chloroplasts. In the presence of ABA, most of the M chloroplasts showed the aggregative movement in response to blue light but not red light. Together these results suggest that ROS are not involved in signal transduction for the aggregative movement, and ABA can shift the blue light-induced avoidance movement of C(4)-M chloroplasts to the aggregative movement.

  1. The role of the atypical kinases ABC1K7 and ABC1K8 in abscisic acid responses

    Directory of Open Access Journals (Sweden)

    Anna eManara

    2016-03-01

    Full Text Available The ABC1K family of atypical kinases (activity of bc1 complex kinase is represented in bacteria, archaea and eukaryotes. In plants they regulate diverse physiological processes in the chloroplasts and mitochondria, but their precise functions are poorly defined. ABC1K7 and ABC1K8 are probably involved in oxidative stress responses, isoprenyl lipid synthesis and distribution of iron within chloroplasts. Because reactive oxygen species take part in abscisic acid (ABA-mediated processes, we investigated the functions of ABC1K7 and ABC1K8 during germination, stomatal movement and leaf senescence. Both genes were upregulated by ABA treatment and some ABA-responsive physiological processes were affected in abc1k7 and abc1k8 mutants. Germination was more severely affected by ABA, osmotic stress and salt stress in the single and double mutants; the stomatal aperture was smaller in the mutants under standard growth conditions and was not further reduced by exogenous ABA application; ABA-induced senescence symptoms were more severe in the leaves of the single and double mutants compared to wild type leaves. Taken together, our results suggest that ABC1K7 and ABC1K8 might be involved in the cross-talk between ABA and ROS signaling.

  2. Inhibition of inward K+ channels and stomatal response by abscisic acid: an intracellular locus of phytohormone action.

    OpenAIRE

    Schwartz, A; Wu, W. H.; Tucker, E B; Assmann, S M

    1994-01-01

    Abscisic acid (ABA), a plant hormone whose production is stimulated by water stress, reduces the apertures of stomatal pores in the leaf surface, thereby lessening transpirational water loss. It has been thought that inhibition of stomatal opening and promotion of stomatal closure by ABA are initiated by the binding of extracellular ABA to a receptor located in the guard-cell plasma membrane. However, in the present research, we employ three distinct experimental approaches to demonstrate tha...

  3. Mitogen-activated protein kinase and abscisic acid signal transduction

    NARCIS (Netherlands)

    Heimovaara-Dijkstra, S.; Testerink, C.; Wang, M.

    1998-01-01

    The phytohormone abscisic acid (ABA) is a classical plant hormone, responsible for regulation of abscission, diverse aspects of plant and seed development, stress responses and germination. It was found that ABA signal transduction in plants can involve the activity of type 2C-phosphatases (PP2C), c

  4. Arabidopsis plastid AMOS1/EGY1 integrates abscisic acid signaling to regulate global gene expression response to ammonium stress

    KAUST Repository

    Li, Baohai

    2012-10-12

    Ammonium (NH4 +) is a ubiquitous intermediate of nitrogen metabolism but is notorious for its toxic effects on most organisms. Extensive studies of the underlying mechanisms of NH4 + toxicity have been reported in plants, but it is poorly understood how plants acclimate to high levels of NH4 +. Here, we identified an Arabidopsis (Arabidopsis thaliana) mutant, ammonium overly sensitive1 (amos1), that displays severe chlorosis under NH4 + stress. Map-based cloning shows amos1 to carry a mutation in EGY1 (for ethylene-dependent, gravitropism-deficient, and yellow-green-like protein1), which encodes a plastid metalloprotease. Transcriptomic analysis reveals that among the genes activated in response to NH4 +, 90% are regulated dependent on AMOS1/ EGY1. Furthermore, 63% of AMOS1/EGY1-dependent NH4 +-activated genes contain an ACGTG motif in their promoter region, a core motif of abscisic acid (ABA)-responsive elements. Consistent with this, our physiological, pharmacological, transcriptomic, and genetic data show that ABA signaling is a critical, but not the sole, downstream component of the AMOS1/EGY1-dependent pathway that regulates the expression of NH4 +-responsive genes and maintains chloroplast functionality under NH4 + stress. Importantly, abi4 mutants defective in ABA-dependent and retrograde signaling, but not ABA-deficient mutants, mimic leaf NH4 + hypersensitivity of amos1. In summary, our findings suggest that an NH4 +-responsive plastid retrograde pathway, which depends on AMOS1/EGY1 function and integrates with ABA signaling, is required for the regulation of expression of the presence of high NH4 + levels. © 2012 American Society of Plant Biologists. All Rights Reserved.

  5. Water stress responses of tomato mutants impaired in hormone biosynthesis reveal abscisic acid, jasmonic acid and salicylic acid interactions

    Directory of Open Access Journals (Sweden)

    Valeria eMuñoz

    2015-11-01

    Full Text Available To investigate the putative crosstalk between JA and ABA in Solanum lycopersicum plants in response to drought, suppressor of prosystemin-mediated responses2 (spr2, JA-deficient and flacca (flc, ABA-deficient mutants together with the naphthalene/salicylate hydroxylase (NahG transgenic (SA-deficient line were used. Hormone profiling and gene expression of key enzymes in ABA, JA and SA biosynthesis were analyzed during early stages of drought. ABA accumulation was comparable in spr2 and wild type (WT plants whereas expression of 9-cis-epoxycarotenoid dioxygenase 1 (NCED1 and NCED2 was different, implying a compensation mechanism between NCED genes and an organ-specific regulation of NCED1 expression. JA levels and 12-oxo-phytodienoic acid reductase 3 (OPR3 expression in flc plants suggest that ABA regulates the induction of the OPR3 gene in roots. By contrast, ABA treatment to flc plants leads to a reduction of JA and SA contents. Furthermore, different pattern of SA accumulation (and expression of isochorismate synthase and phenylalanine ammonia lyase 1 was observed between WT seedlings and mutants, suggesting that SA plays an important role on the early response of tomato plants to drought and also that JA and ABA modulate its biosynthesis. Finally, hormone profiling in spr2 and NahG plants indicate a crosstalk between JA and SA that could enhance tolerance of tomato to water stress.

  6. Water Stress Responses of Tomato Mutants Impaired in Hormone Biosynthesis Reveal Abscisic Acid, Jasmonic Acid and Salicylic Acid Interactions

    Science.gov (United States)

    Muñoz-Espinoza, Valeria A.; López-Climent, María F.; Casaretto, José A.; Gómez-Cadenas, Aurelio

    2015-01-01

    To investigate the putative crosstalk between JA and ABA in Solanum lycopersicum plants in response to drought, suppressor of prosystemin-mediated responses2 (spr2, JA-deficient) and flacca (flc, ABA-deficient) mutants together with the naphthalene/salicylate hydroxylase (NahG) transgenic (SA-deficient) line were used. Hormone profiling and gene expression of key enzymes in ABA, JA and SA biosynthesis were analyzed during early stages of drought. ABA accumulation was comparable in spr2 and wild type (WT) plants whereas expression of 9-cis-epoxycarotenoid dioxygenase 1 (NCED1) and NCED2 was different, implying a compensation mechanism between NCED genes and an organ-specific regulation of NCED1 expression. JA levels and 12-oxo-phytodienoic acid reductase 3 (OPR3) expression in flc plants suggest that ABA regulates the induction of the OPR3 gene in roots. By contrast, ABA treatment to flc plants leads to a reduction of JA and SA contents. Furthermore, different pattern of SA accumulation (and expression of isochorismate synthase and phenylalanine ammonia lyase 1) was observed between WT seedlings and mutants, suggesting that SA plays an important role on the early response of tomato plants to drought and also that JA and ABA modulate its biosynthesis. Finally, hormone profiling in spr2 and NahG plants indicate a crosstalk between JA and SA that could enhance tolerance of tomato to water stress. PMID:26635826

  7. Impaired increase of plasma abscisic Acid in response to oral glucose load in type 2 diabetes and in gestational diabetes.

    Science.gov (United States)

    Ameri, Pietro; Bruzzone, Santina; Mannino, Elena; Sociali, Giovanna; Andraghetti, Gabriella; Salis, Annalisa; Ponta, Monica Laura; Briatore, Lucia; Adami, Giovanni F; Ferraiolo, Antonella; Venturini, Pier Luigi; Maggi, Davide; Cordera, Renzo; Murialdo, Giovanni; Zocchi, Elena

    2015-01-01

    The plant hormone abscisic acid (ABA) is present and active in humans, regulating glucose homeostasis. In normal glucose tolerant (NGT) human subjects, plasma ABA (ABAp) increases 5-fold after an oral glucose load. The aim of this study was to assess the effect of an oral glucose load on ABAp in type 2 diabetes (T2D) subjects. We chose two sub-groups of patients who underwent an oral glucose load for diagnostic purposes: i) 9 treatment-naive T2D subjects, and ii) 9 pregnant women with gestational diabetes (GDM), who underwent the glucose load before and 8-12 weeks after childbirth. Each group was compared with matched NGT controls. The increase of ABAp in response to glucose was found to be abrogated in T2D patients compared to NGT controls. A similar result was observed in the women with GDM compared to pregnant NGT controls; 8-12 weeks after childbirth, however, fasting ABAp and ABAp response to glucose were restored to normal in the GDM subjects, along with glucose tolerance. We also retrospectively compared fasting ABAp before and after bilio-pancreatic diversion (BPD) in obese, but not diabetic subjects, and in obese T2D patients, in which BPD resulted in the resolution of diabetes. Compared to pre-BPD values, basal ABAp significantly increased 1 month after BPD in T2D as well as in NGT subjects, in parallel with a reduction of fasting plasma glucose. These results indicate an impaired hyperglycemia-induced ABAp increase in T2D and in GDM and suggest a beneficial effect of elevated ABAp on glycemic control.

  8. Impaired increase of plasma abscisic Acid in response to oral glucose load in type 2 diabetes and in gestational diabetes.

    Directory of Open Access Journals (Sweden)

    Pietro Ameri

    Full Text Available The plant hormone abscisic acid (ABA is present and active in humans, regulating glucose homeostasis. In normal glucose tolerant (NGT human subjects, plasma ABA (ABAp increases 5-fold after an oral glucose load. The aim of this study was to assess the effect of an oral glucose load on ABAp in type 2 diabetes (T2D subjects. We chose two sub-groups of patients who underwent an oral glucose load for diagnostic purposes: i 9 treatment-naive T2D subjects, and ii 9 pregnant women with gestational diabetes (GDM, who underwent the glucose load before and 8-12 weeks after childbirth. Each group was compared with matched NGT controls. The increase of ABAp in response to glucose was found to be abrogated in T2D patients compared to NGT controls. A similar result was observed in the women with GDM compared to pregnant NGT controls; 8-12 weeks after childbirth, however, fasting ABAp and ABAp response to glucose were restored to normal in the GDM subjects, along with glucose tolerance. We also retrospectively compared fasting ABAp before and after bilio-pancreatic diversion (BPD in obese, but not diabetic subjects, and in obese T2D patients, in which BPD resulted in the resolution of diabetes. Compared to pre-BPD values, basal ABAp significantly increased 1 month after BPD in T2D as well as in NGT subjects, in parallel with a reduction of fasting plasma glucose. These results indicate an impaired hyperglycemia-induced ABAp increase in T2D and in GDM and suggest a beneficial effect of elevated ABAp on glycemic control.

  9. Abscisic acid refines the synthesis of chloroplast proteins in maize (Zea mays in response to drought and light.

    Directory of Open Access Journals (Sweden)

    Xiuli Hu

    Full Text Available To better understand abscisic acid (ABA regulation of the synthesis of chloroplast proteins in maize (Zea mays L. in response to drought and light, we compared leaf proteome differences between maize ABA-deficient mutant vp5 and corresponding wild-type Vp5 green and etiolated seedlings exposed to drought stress. Proteins extracted from the leaves of Vp5 and vp5 seedlings were used for two-dimensional electrophoresis (2-DE and subsequent matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF mass spectrometry (MS. After Coomassie brilliant blue staining, approximately 450 protein spots were reproducibly detected on 2-DE gels. A total of 36 differentially expressed protein spots in response to drought and light were identified using MALDI-TOF MS and their subcellular localization was determined based on the annotation of reviewed accession in UniProt Knowledgebase and the software prediction. As a result, corresponding 13 proteins of the 24 differentially expressed protein spots were definitely localized in chloroplasts and their expression was in an ABA-dependent way, including 6 up-regulated by both drought and light, 5 up-regulated by drought but down-regulated by light, 5 up-regulated by light but down-regulated by drought; 5 proteins down-regulated by drought were mainly those involved in photosynthesis and ATP synthesis. Thus, the results in the present study supported the vital role of ABA in regulating the synthesis of drought- and/or light-induced proteins in maize chloroplasts and would facilitate the functional characterization of ABA-induced chloroplast proteins in C(4 plants.

  10. Impaired Increase of Plasma Abscisic Acid in Response to Oral Glucose Load in Type 2 Diabetes and in Gestational Diabetes

    OpenAIRE

    Pietro Ameri; Santina Bruzzone; Elena Mannino; Giovanna Sociali; Gabriella Andraghetti; Annalisa Salis; Monica Laura Ponta; Lucia Briatore; Adami, Giovanni F.; Antonella Ferraiolo; Pier Luigi Venturini; Davide Maggi; Renzo Cordera; Giovanni Murialdo; Elena Zocchi

    2015-01-01

    The plant hormone abscisic acid (ABA) is present and active in humans, regulating glucose homeostasis. In normal glucose tolerant (NGT) human subjects, plasma ABA (ABAp) increases 5-fold after an oral glucose load. The aim of this study was to assess the effect of an oral glucose load on ABAp in type 2 diabetes (T2D) subjects. We chose two sub-groups of patients who underwent an oral glucose load for diagnostic purposes: i) 9 treatment-naive T2D subjects, and ii) 9 pregnant women with gestati...

  11. Expression Analysis of Four Peroxiredoxin Genes from Tamarix hispida in Response to Different Abiotic Stresses and Exogenous Abscisic Acid (ABA

    Directory of Open Access Journals (Sweden)

    Guiyan Yang

    2012-03-01

    Full Text Available Peroxiredoxins (Prxs are a recently discovered family of antioxidant enzymes that catalyze the reduction of peroxides and alkyl peroxides. In this study, four Prx genes (named as ThPrxII, ThPrxIIE, ThPrxIIF, and Th2CysPrx were cloned from Tamarix hispida. Their expression profiles in response to stimulus of NaCl, NaHCO3, PEG, CdCl2 and abscisic acid (ABA in roots, stems and leaves of T. hispida were investigated using real-time RT-PCR. The results showed that the four ThPrxs were all expressed in roots, stems and leaves. Furthermore, the transcript levels of ThPrxIIE and ThPrxII were the lowest and the highest, respectively, in all tissue types. All the ThPrx genes were induced by both NaCl and NaHCO3 and reached their highest expression levels at the onset of stress in roots. Under PEG and CdCl2 stress, the expression patterns of these ThPrxs showed temporal and spatial specificity. The expressions of the ThPrxs were all differentially regulated by ABA, indicating that they are all involved in the ABA signaling pathway. These findings reveal a complex regulation of Prxs that is dependent on the type of Prx, tissue, and the signaling molecule. The divergence of the stress-dependent transcriptional regulation of the ThPrx gene family in T. hispida may provide an essential basis for the elucidation of Prx function in future work.

  12. Roles of Abscisic Acid in Fruit Ripening

    Directory of Open Access Journals (Sweden)

    Sutthiwal SETHA

    2012-12-01

    Full Text Available Abscisic acid (ABA is a plant growth regulator, and it plays a variety of important roles throughout a plant’s life cycle. These roles include seed development and dormancy, plant response to environmental stresses, and fruit ripening. ABA concentration is very low in unripe fruit, but it increases as a fruit ripens, so it is therefore believed that ABA plays an important role in regulating the rate of fruit ripening. This article reviews the effect of ABA on ripening and quality of climacteric and non-climacteric fruits. The effects of ABA application on fruit ripening are subsequently discussed. Moreover, it is found that during fruit ripening, ABA also contributes to other functions, such as ethylene and respiratory metabolism, pigment and color changes, phenolic metabolism and nutritional contents, cell wall metabolism and fruit softening, and sugar and acid metabolism. These processes are all discussed as part of the relationship between ABA and fruit ripening, and the possibilities for its commercial application and use are highlighted.

  13. GENETIC ANALYSIS OF ABSCISIC ACID BIOSYNTHESIS

    Energy Technology Data Exchange (ETDEWEB)

    MCCARTY D R

    2012-01-10

    The carotenoid cleavage dioxygenases (CCD) catalyze synthesis of a variety of apo-carotenoid secondary metabolites in plants, animals and bacteria. In plants, the reaction catalyzed by the 11, 12, 9-cis-epoxy carotenoid dioxygenase (NCED) is the first committed and key regulated step in synthesis of the plant hormone, abscisic acid (ABA). ABA is a key regulator of plant stress responses and has critical functions in normal root and seed development. The molecular mechanisms responsible for developmental control of ABA synthesis in plant tissues are poorly understood. Five of the nine CCD genes present in the Arabidopsis genome encode NCED's involved in control of ABA synthesis in the plant. This project is focused on functional analysis of these five AtNCED genes as a key to understanding developmental regulation of ABA synthesis and dissecting the role of ABA in plant development. For this purpose, the project developed a comprehensive set of gene knockouts in the AtNCED genes that facilitate genetic dissection of ABA synthesis. These mutants were used in combination with key molecular tools to address the following specific objectives: (1) the role of ABA synthesis in root development; (2) developmental control of ABA synthesis in seeds; (3) analysis of ATNCED over-expressers; (4) preliminary crystallography of the maize VP14 protein.

  14. Abscisic Acid Receptors: Past, Present and Future

    Institute of Scientific and Technical Information of China (English)

    Jianjun Guo; Xiaohan Yang; David J. Weston; Jin-Gui Chen

    2011-01-01

    Abscisic acid (ABA) is the key plant stress hormone. Consistent with the earlier studies in support of the presence of both membrane- and cytoplasm-localized ABA receptors, recent studies have identified multiple ABA receptors located in various subcellular locations. These include a chloroplast envelope-localized receptor (the H subunit of Chloroplast Mg2+-chelatase/ABA Receptor), two plasma membrane-localized receptors (G-protein Coupled Receptor 2 and GPCR-type G proteins),and one cytosol/nucleus-localized Pyrabactin Resistant (PYR)/PYR-Like (PYL)/Regulatory Component of ABA Receptor 1 (RCAR). Although the downstream molecular events for most of the identified ABA receptors are currently unknown, one of them, PYR/PYL/RCAR was found to directly bind and regulate the activity of a long-known central regulator of ABA signaling, the A-group protein phosphatase 2C (PP2C). Together with the Sucrose Non-fermentation Kinase Subfamily 2 (SnRK2s) protein kinases, a central signaling complex (ABA-PYR-PP2Cs-SnRK2s) that is responsible for ABA signal perception and transduction is supported by abundant genetic, physiological, biochemical and structural evidence. The identification of multiple ABA receptors has advanced our understanding of ABA signal perception and transduction while adding an extra layer of complexity.

  15. Molecular cloning and characterization of drought stress responsive abscisic acid-stress-ripening (Asr 1) gene from wild jujube, Ziziphus nummularia (Burm.f.) Wight & Arn.

    Science.gov (United States)

    Padaria, Jasdeep Chatrath; Yadav, Radha; Tarafdar, Avijit; Lone, Showkat Ahmad; Kumar, Kanika; Sivalingam, Palaiyur Nanjappan

    2016-08-01

    Drought is a calamitous abiotic stress hampering agricultural productivity all over the world and its severity is likely to increase further. Abscisic acid-stress-ripening proteins (ASR), are a group of small hydrophilic proteins which are induced by abscisic acid, stress and ripening in many plants. In the present study, ZnAsr 1 gene was fully characterized for the first time from Ziziphus nummularia, which is one of the most low water forbearing plant. Full length ZnAsr 1 gene was characterised and in silico analysis of ZnASR1 protein was done for predicting its phylogeny and physiochemical properties. To validate transcriptional pattern of ZnAsr 1 in response to drought stress, expression profiling in polyethylene glycol (PEG) induced Z. nummularia seedlings was studied by RT-qPCR analysis and heterologous expression of the recombinant ZnAsr1 in Escherichia coli. The nucleotide sequence analysis revealed that the complete open reading frame of ZnAsr 1 is 819 bp long encoding a protein of 273 amino acid residues, consisting of a histidine rich N terminus with an abscisic acid/water deficit stress domain and a nuclear targeting signal at the C terminus. In expression studies, ZnAsr 1 gene was found to be highly upregulated under drought stress and recombinant clones of E. coli cells expressing ZnASR1 protein showed better survival in PEG containing media. ZnAsr1 was proven to enhance drought stress tolerance in the recombinant E.coli cells expressing ZnASR1. The cloned ZnAsr1 after proper validation in a plant system, can be used to develop drought tolerant transgenic crops.

  16. Conjugates of abscisic acid, brassinosteroids, ethylene, gibberellins, and jasmonates.

    Science.gov (United States)

    Piotrowska, Alicja; Bajguz, Andrzej

    2011-12-01

    Phytohormones, including auxins, abscisic acid, brassinosteroids, cytokinins, ethylene, gibberellins, and jasmonates, are involved in all aspects of plant growth, and developmental processes as well as environmental responses. However, our understanding of hormonal homeostasis is far from complete. Phytohormone conjugation is considered as a part of the mechanism to control cellular levels of these compounds. Active phytohormones are changed into multiple forms by acylation, esterification or glycosylation, for example. It seems that conjugated compounds could serve as pool of inactive phytohormones that can be converted to active forms by de-conjugation reactions. Some conjugates are thought to be temporary storage forms, from which free active hormones can be released after hydrolysis. It is also believed that conjugation serves functions, such as irreversible inactivation, transport, compartmentalization, and protection against degradation. The nature of abscisic acid, brassinosteroid, ethylene, gibberellin, and jasmonate conjugates is discussed.

  17. Inhibition of inward K+ channels and stomatal response by abscisic acid: an intracellular locus of phytohormone action.

    Science.gov (United States)

    Schwartz, A; Wu, W H; Tucker, E B; Assmann, S M

    1994-04-26

    Abscisic acid (ABA), a plant hormone whose production is stimulated by water stress, reduces the apertures of stomatal pores in the leaf surface, thereby lessening transpirational water loss. It has been thought that inhibition of stomatal opening and promotion of stomatal closure by ABA are initiated by the binding of extracellular ABA to a receptor located in the guard-cell plasma membrane. However, in the present research, we employ three distinct experimental approaches to demonstrate that ABA can act from within guard cells to regulate stomatal apertures. (i) The extent to which ABA inhibits stomatal opening and promotes stomatal closure in Commelina communis L. is proportional to the extent of ABA uptake, as assayed with [3H]ABA. (ii) Direct microinjection of ABA into the cytoplasm of Commelina guard cells precipitates stomatal closure. (iii) Application of ABA to the cytosol of Vicia faba L. guard-cell protoplasts via patch-clamp techniques inhibits inward K+ currents, an effect sufficient to inhibit stomatal opening. These results demonstrate an intracellular locus of phytohormone action and imply that the search for hormone receptor proteins should be extended to include intracellular compartments.

  18. Presence of abscisic acid, a phytohormone, in the mammalian brain.

    Science.gov (United States)

    Le Page-Degivry, M T; Bidard, J N; Rouvier, E; Bulard, C; Lazdunski, M

    1986-01-01

    This paper reports the presence of abscisic acid, one of the most important phytohormones, in the central nervous system of pigs and rats. The identification of this hormone in brain was made after extensive purification by using a radioimmunoassay that is very specific for (+)-cis-abscisic acid. The final product of purification from mammalian brain has the same properties as authentic abscisic acid: it crossreacts in the radioimmunoassay for the phytohormone and it has the same retention properties and the same gas chromatography/mass spectrometry characteristics. Moreover, like (+)-cis-abscisic acid itself, the brain factor inhibits stomatal apertures of abaxial epidermis strips of Setcreasea purpurea Boom (Commelinaceae). The presence of abscisic acid conjugates that are present in plants has also been identified in brain. Images PMID:2937056

  19. Presence of abscisic acid, a phytohormone, in the mammalian brain

    Energy Technology Data Exchange (ETDEWEB)

    Le Page-Degivry, M.T.; Bidard, J.N.; Rouvier, E.; Bulard, C.; Lazdunski, M.

    1986-02-01

    This paper reports the presence of abscisic acid, one of the most important phytohormones, in the central nervous system of pigs and rats. The identification of this hormone in brain was made after extensive purification by using a radioimmunoassay that is very specific for (+)-cis-abscisic acid. The final product of purification from mammalian brain has the same properties as authentic abscisic acid: it crossreacts in the radioimmunoassay for the phytohormone and it has the same retention properties and the same gas chromatography/mass spectrometry characteristics. Moreover, like (+)-cis-abscisic acid itself, the brain factor inhibits stomatal apertures of abaxial epidermis strips of Setcreasea purpurea Boom (Commelinaceae). The presence of abscisic acid conjugates that are present in plants has also been identified in brain.

  20. Arabidopsis RADICAL-INDUCED CELL DEATH1 belongs to the WWE protein-protein interaction domain protein family and modulates abscisic acid, ethylene, and methyl jasmonate responses.

    Science.gov (United States)

    Ahlfors, Reetta; Lång, Saara; Overmyer, Kirk; Jaspers, Pinja; Brosché, Mikael; Tauriainen, Airi; Kollist, Hannes; Tuominen, Hannele; Belles-Boix, Enric; Piippo, Mirva; Inzé, Dirk; Palva, E Tapio; Kangasjärvi, Jaakko

    2004-07-01

    Experiments with several Arabidopsis thaliana mutants have revealed a web of interactions between hormonal signaling. Here, we show that the Arabidopsis mutant radical-induced cell death1 (rcd1), although hypersensitive to apoplastic superoxide and ozone, is more resistant to chloroplastic superoxide formation, exhibits reduced sensitivity to abscisic acid, ethylene, and methyl jasmonate, and has altered expression of several hormonally regulated genes. Furthermore, rcd1 has higher stomatal conductance than the wild type. The rcd1-1 mutation was mapped to the gene At1g32230 where it disrupts an intron splice site resulting in a truncated protein. RCD1 belongs to the (ADP-ribosyl)transferase domain-containing subfamily of the WWE protein-protein interaction domain protein family. The results suggest that RCD1 could act as an integrative node in hormonal signaling and in the regulation of several stress-responsive genes.

  1. In vitro Transient Expression System of Latex C-serum was used for Analysis of Hevein Promoter in Response to Abscisic Acid in Hevea brasiliensis

    Institute of Scientific and Technical Information of China (English)

    Xiao-Wen Fei; Xiao-Dong Deng

    2008-01-01

    Hevein has been found to be an essential element in coagulation of rubber particles in latex of rubber trees. In a previous study, we cloned a 1 241-bp fragment of a 5' upstream region of the hevein gene by genome walking. This fragment was analyzed by a 5' end nested deletion method in the present study, fused with a uidA (gus) gene to produce a series of tested constructs, which were transferred into C-serum of latex and the Gus activities were detected. Results showed that the fragment from -749 to -292 was sufficient for expression of gus gene in latex, and the fragment from -292 to -168 was crucial in response to abscisic acid inducement. In a transient transgenic test of rubber leaf with particle bombardment, construct Hev749 conferred gus-specific expression in veins, in which the latex tubes mainly distributed. This implies that the fragment from -749 to -292 was laticiferous-specific.

  2. Seed response to strigolactone is controlled by abscisic acid-independent DNA methylation in the obligate root parasitic plant, Phelipanche ramosa L. Pomel.

    Science.gov (United States)

    Lechat, Marc-Marie; Brun, Guillaume; Montiel, Grégory; Véronési, Christophe; Simier, Philippe; Thoiron, Séverine; Pouvreau, Jean-Bernard; Delavault, Philippe

    2015-06-01

    Seed dormancy release of the obligate root parasitic plant, Phelipanche ramosa, requires a minimum 4-day conditioning period followed by stimulation by host-derived germination stimulants, such as strigolactones. Germination is then mediated by germination stimulant-dependent activation of PrCYP707A1, an abscisic acid catabolic gene. The molecular mechanisms occurring during the conditioning period that silence PrCYP707A1 expression and regulate germination stimulant response are almost unknown. Here, global DNA methylation quantification associated with pharmacological approaches and cytosine methylation analysis of the PrCYP707A1 promoter were used to investigate the modulation and possible role of DNA methylation during the conditioning period and in the PrCYP707A1 response to GR24, a synthetic strigolactone analogue. Active global DNA demethylation occurs during the conditioning period and is required for PrCYP707A1 activation by GR24 and for subsequent seed germination. Treatment with 5-azacytidine, a DNA-hypomethylating molecule, reduces the length of the conditioning period. Conversely, hydroxyurea, a hypermethylating agent, inhibits PrCYP707A1 expression and seed germination. Methylated DNA immunoprecipitation followed by PCR experiments and bisulfite sequencing revealed that DNA demethylation particularly impacts a 78-nucleotide sequence in the PrCYP707A1 promoter. The results here demonstrate that the DNA methylation status during the conditioning period plays a crucial role independently of abscisic acid in the regulation of P. ramosa seed germination by controlling the strigolactone-dependent expression of PrCYP707A1.

  3. The putative E3 ubiquitin ligase ECERIFERUM9 regulates abscisic acid biosynthesis and response during seed germination and postgermination growth in arabidopsis

    KAUST Repository

    Zhao, Huayan

    2014-05-08

    The ECERIFERUM9 (CER9) gene encodes a putative E3 ubiquitin ligase that functions in cuticle biosynthesis and the maintenance of plant water status. Here, we found that CER9 is also involved in abscisic acid (ABA) signaling in seeds and young seedlings of Arabidopsis (Arabidopsis thaliana). The germinated embryos of the mutants exhibited enhanced sensitivity to ABA during the transition from reversible dormancy to determinate seedling growth. Expression of the CER9 gene is closely related to ABA levels and displays a similar pattern to that of ABSCISIC ACID-INSENSITIVE5 (ABI5), which encodes a positive regulator of ABA responses in seeds. cer9 mutant seeds exhibited delayed germination that is independent of seed coat permeability. Quantitative proteomic analyses showed that cer9 seeds had a protein profile similar to that of the wild type treated with ABA. Transcriptomics analyses revealed that genes involved in ABA biosynthesis or signaling pathways were differentially regulated in cer9 seeds. Consistent with this, high levels of ABA were detected in dry seeds of cer9. Blocking ABA biosynthesis by fluridone treatment or by combining an ABA-deficient mutation with cer9 attenuated the phenotypes of cer9. Whereas introduction of the abi1-1, abi3-1, or abi4-103 mutation could completely eliminate the ABA hypersensitivity of cer9, introduction of abi5 resulted only in partial suppression. These results indicate that CER9 is a novel negative regulator of ABA biosynthesis and the ABA signaling pathway during seed germination. © 2014 American Society of Plant Biologists. All Rights Reserved.

  4. Uprooting an abscisic acid paradigm: Shoots are the primary source.

    Science.gov (United States)

    McAdam, Scott A M; Manzi, Matías; Ross, John J; Brodribb, Timothy J; Gómez-Cadenas, Aurelio

    2016-06-02

    In the past, a conventional wisdom has been that abscisic acid (ABA) is a xylem-transported hormone that is synthesized in the roots, while acting in the shoot to close stomata in response to a decrease in plant water status. Now, however, evidence from two studies, which we have conducted independently, challenges this root-sourced ABA paradigm. We show that foliage-derived ABA has a major influence over root development and that leaves are the predominant location for ABA biosynthesis during drought stress.

  5. Rice G-protein subunits qPE9-1 and RGB1 play distinct roles in abscisic acid responses and drought adaptation.

    Science.gov (United States)

    Zhang, Dong-Ping; Zhou, Yong; Yin, Jian-Feng; Yan, Xue-Jiao; Lin, Sheng; Xu, Wei-Feng; Baluška, František; Wang, Yi-Ping; Xia, Yi-Ji; Liang, Guo-hua; Liang, Jian-Sheng

    2015-10-01

    Heterotrimeric GTP-binding protein (G-protein)-mediated abscisic acid (ABA) and drought-stress responses have been documented in numerous plant species. However, our understanding of the function of rice G-protein subunits in ABA signalling and drought tolerance is limited. In this study, the function of G-protein subunits in ABA response and drought resistance in rice plants was explored. It was found that the transcription level of qPE9-1 (rice Gγ subunit) gradually decreased with increasing ABA concentration and the lack of qPE9-1 showed an enhanced drought tolerance in rice plants. In contrast, mRNA levels of RGB1 (rice Gβ subunit) were significantly upregulated by ABA treatment and the lack of RGB1 led to reduced drought tolerance. Furthermore, the results suggested that qPE9-1 negatively regulates the ABA response by suppressing the expression of key transcription factors involved in ABA and stress responses, while RGB1 positively regulates ABA biosynthesis by upregulating NCED gene expression under both normal and drought stress conditions. Taken together, it is proposed that RGB1 is a positive regulator of the ABA response and drought adaption in rice plants, whereas qPE9-1 is modulated by RGB1 and functions as a negative regulator in the ABA-dependent drought-stress responses.

  6. Arabidopsis HOOKLESS1 Regulates Responses to Pathogens and Abscisic Acid through Interaction with MED18 and Acetylation of WRKY33 and ABI5 Chromatin.

    Science.gov (United States)

    Liao, Chao-Jan; Lai, Zhibing; Lee, Sanghun; Yun, Dae-Jin; Mengiste, Tesfaye

    2016-07-01

    Arabidopsis thaliana HOOKLESS1 (HLS1) encodes a putative histone acetyltransferase with known functions in seedling growth. Here, we show that HLS1 regulates plant responses to pathogens and abscisic acid (ABA) through histone acetylation at chromatin of target loci. The hls1 mutants show impaired responses to bacterial and fungal infection, accelerated senescence, and impaired responses to ABA. HLS1 modulates the expression of WRKY33 and ABA INSENSITIVE5 (ABI5), known regulators of pathogen and ABA responses, respectively, through direct association with these loci. Histone 3 acetylation (H3Ac), a positive mark of transcription, at WRKY33 and ABI5 requires HLS1 function. ABA treatment and pathogen infection enhance HLS1 recruitment and H3Ac at WRKY33. HLS1 associates with Mediator, a eukaryotic transcription coregulatory complex, through direct interaction with mediator subunit 18 (MED18), with which it shares multiple functions. HLS1 recruits MED18 to the WRKY33 promoter, boosting WKRY33 expression, suggesting the synergetic action of HLS1 and MED18. By contrast, MED18 recruitment to ABI5 and transcriptional activation are independent of HLS1. ABA-mediated priming of resistance to fungal infection was abrogated in hls1 and wrky33 mutants but correlated with ABA-induced HLS1 accumulation. In sum, HLS1 provides a regulatory node in pathogen and hormone response pathways through interaction with the Mediator complex and important transcription factors.

  7. Ethylene Responses in Rice Roots and Coleoptiles Are Differentially Regulated by a Carotenoid Isomerase-Mediated Abscisic Acid Pathway[OPEN

    Science.gov (United States)

    Yin, Cui-Cui; Ma, Biao; Collinge, Derek Phillip; Pogson, Barry James; He, Si-Jie; Xiong, Qing; Duan, Kai-Xuan; Chen, Hui; Yang, Chao; Lu, Xiang; Wang, Yi-Qin; Zhang, Wan-Ke; Chu, Cheng-Cai; Sun, Xiao-Hong; Fang, Shuang; Chu, Jin-Fang; Lu, Tie-Gang; Chen, Shou-Yi; Zhang, Jin-Song

    2015-01-01

    Ethylene and abscisic acid (ABA) act synergistically or antagonistically to regulate plant growth and development. ABA is derived from the carotenoid biosynthesis pathway. Here, we analyzed the interplay among ethylene, carotenoid biogenesis, and ABA in rice (Oryza sativa) using the rice ethylene response mutant mhz5, which displays a reduced ethylene response in roots but an enhanced ethylene response in coleoptiles. We found that MHZ5 encodes a carotenoid isomerase and that the mutation in mhz5 blocks carotenoid biosynthesis, reduces ABA accumulation, and promotes ethylene production in etiolated seedlings. ABA can largely rescue the ethylene response of the mhz5 mutant. Ethylene induces MHZ5 expression, the production of neoxanthin, an ABA biosynthesis precursor, and ABA accumulation in roots. MHZ5 overexpression results in enhanced ethylene sensitivity in roots and reduced ethylene sensitivity in coleoptiles. Mutation or overexpression of MHZ5 also alters the expression of ethylene-responsive genes. Genetic studies revealed that the MHZ5-mediated ABA pathway acts downstream of ethylene signaling to inhibit root growth. The MHZ5-mediated ABA pathway likely acts upstream but negatively regulates ethylene signaling to control coleoptile growth. Our study reveals novel interactions among ethylene, carotenogenesis, and ABA and provides insight into improvements in agronomic traits and adaptive growth through the manipulation of these pathways in rice. PMID:25841037

  8. Putrescine Is Involved in Arabidopsis Freezing Tolerance and Cold Acclimation by Regulating Abscisic Acid Levels in Response to Low Temperature1

    Science.gov (United States)

    Cuevas, Juan C.; López-Cobollo, Rosa; Alcázar, Rubén; Zarza, Xavier; Koncz, Csaba; Altabella, Teresa; Salinas, Julio; Tiburcio, Antonio F.; Ferrando, Alejandro

    2008-01-01

    The levels of endogenous polyamines have been shown to increase in plant cells challenged with low temperature; however, the functions of polyamines in the regulation of cold stress responses are unknown. Here, we show that the accumulation of putrescine under cold stress is essential for proper cold acclimation and survival at freezing temperatures because Arabidopsis (Arabidopsis thaliana) mutants defective in putrescine biosynthesis (adc1, adc2) display reduced freezing tolerance compared to wild-type plants. Genes ADC1 and ADC2 show different transcriptional profiles upon cold treatment; however, they show similar and redundant contributions to cold responses in terms of putrescine accumulation kinetics and freezing sensitivity. Our data also demonstrate that detrimental consequences of putrescine depletion during cold stress are due, at least in part, to alterations in the levels of abscisic acid (ABA). Reduced expression of NCED3, a key gene involved in ABA biosynthesis, and down-regulation of ABA-regulated genes are detected in both adc1 and adc2 mutant plants under cold stress. Complementation analysis of adc mutants with ABA and reciprocal complementation tests of the aba2-3 mutant with putrescine support the conclusion that putrescine controls the levels of ABA in response to low temperature by modulating ABA biosynthesis and gene expression. PMID:18701673

  9. Overexpression of the NDR1/HIN1-Like Gene NHL6 Modifies Seed Germination in Response to Abscisic Acid and Abiotic Stresses in Arabidopsis.

    Science.gov (United States)

    Bao, Yan; Song, Wei-Meng; Pan, Jing; Jiang, Chun-Mei; Srivastava, Renu; Li, Bei; Zhu, Lu-Ying; Su, Hong-Yan; Gao, Xiao-Shu; Liu, Hua; Yu, Xiang; Yang, Lei; Cheng, Xian-Hao; Zhang, Hong-Xia

    2016-01-01

    NHL (NDR1/HIN1-like) genes play crucial roles in pathogen induced plant responses to biotic stress. Here, we report the possible function of NHL6 in plant response to abscisic acid (ABA) and abiotic stress. NHL6 was highly expressed in non-germinated seeds, and its expression was strongly induced by ABA and multiple abiotic stress signals. Loss-of-function of NHL6 decreased sensitivity to ABA in the early developmental stages including seed germination and post-germination seedling growth of the nhl6 mutants. However, overexpression of NHL6 increased sensitivity to ABA, salt and osmotic stress of the transgenic plants. Further studies indicated that the increased sensitivity in the 35S::NHL6 overexpressing plants could be a result of both ABA hypersensitivity and increased endogenous ABA accumulation under the stress conditions. It was also seen that the ABA-responsive element binding factors AREB1, AREB2 and ABF3 could regulate NHL6 expression at transcriptional level. Our results indicate that NHL6 plays an important role in the abiotic stresses-induced ABA signaling and biosynthesis, particularly during seed germination and early seedling development in Arabidopsis.

  10. Incorporation of oxygen into abscisic Acid and phaseic Acid from molecular oxygen.

    Science.gov (United States)

    Creelman, R A; Zeevaart, J A

    1984-05-01

    Abscisic acid accumulates in detached, wilted leaves of Xanthium strumarium. When these leaves are subsequently rehydrated, phaseic acid, a catabolite of abscisic acid, accumulates. Analysis by gas chromatography-mass spectrometry of phaseic acid isolated from stressed and subsequently rehydrated leaves placed in an atmosphere containing 20% (18)O(2) and 80% N(2) indicates that one atom of (18)O is incorporated in the 6'-hydroxymethyl group of phaseic acid. This suggests that the enzyme that converts abscisic acid to phaseic acid is an oxygenase.Analysis by gas chromatography-mass spectrometry of abscisic acid isolated from stressed leaves kept in an atmosphere containing (18)O(2) indicates that one atom of (18)O is present in the carboxyl group of abscisic acid. Thus, when abscisic acid accumulates in water-stressed leaves, only one of the four oxygens present in the abscisic acid molecule is derived from molecular oxygen. This suggests that either (a) the oxygen present in the 1'-, 4'-, and one of the two oxygens at the 1-position of abscisic acid arise from water, or (b) there exists a stored precursor with oxygen atoms already present in the 1'- and 4'-positions of abscisic acid which is converted to abscisic acid under conditions of water stress.

  11. S-acylation-dependent association of the calcium sensor CBL2 with the vacuolar membrane is essential for proper abscisic acid responses

    Institute of Scientific and Technical Information of China (English)

    Oliver Batisti(c); Marion Rehers; Amir Akerman; Kathrin Schlücking; Leonie Steinhorst; Shaul Yalovsky; J(o)rg Kudla

    2012-01-01

    Calcineurin B-like (CBL) proteins contribute to decoding calcium signals by interacting with CBL-interacting protein kinases (CIPKs).Currently,there is still very little information about the function and specific targeting mechanisms of CBL proteins that are localized at the vacuolar membrane.In this study,we focus on CBL2,an abundant vacuolar membrane-localized calcium sensor of unknown function from Arabidopsis thaliana.We show that vacuolar targeting of CBL2 is specifically brought about by S-acylation of three cysteine residues in its N-terminus and that CBL2 S-acylation and targeting occur by a Brefeldin A-insensitive pathway.Loss of CBL2 function renders plants hypersensitive to the phytohormone abscisic acid (ABA) during seed germination and only fully S-acylated and properly vacuolar-targeted CBL2 proteins can complement this mutant phenotype.These findings define an S-acylation-dependent vacuolar membrane targeting pathway for proteins and uncover a crucial role of vacuolar calcium sensors in ABA responses.

  12. AtPUB 19, a U-Box E3 Ubiquitin Ligase, Negatively Regulates Abscisic Acid and Drought Responses in Arabidopsis thaliana

    Institute of Scientific and Technical Information of China (English)

    Yong-Chang Liu; Yao-Rong Wu; Xia-He Huang; Jie Sun; Qi Xie

    2011-01-01

    Ubiquitination is an important protein post-translational modification,which is involved in various cellular processes in higher plants,and U-box E3 ligases play important roles in diverse functions in eukaryotes.Here,we describe the functions of Arabidopsis thaliana PUB19 (AtPUB19),which we demonstrated in an in vitro assay to encode a U-box type E3 ubiquitin ligase.AtPUB19 was up-regulated by drought,salt,cold,and abscisic acid (ABA).Down-regulation of AtPUB19led to hypersensitivity to ABA,enhanced ABA-induced stomatal closing,and enhanced drought tolerance,while AtPUB 19overexpression resulted in the reverse phenotypes.Molecular analysis showed that the expression levels of a number of ABA and stress marker genes were altered in both AtPUB 19 overexpressing and atpub 19-1 mutant plants.In summary,our data show that AtPUB19 negatively regulates ABA and drought responses in A.thaliana.

  13. Major latex protein-like protein 43 (MLP43) functions as a positive regulator during abscisic acid responses and confers drought tolerance in Arabidopsis thaliana.

    Science.gov (United States)

    Wang, Yanping; Yang, Li; Chen, Xi; Ye, Tiantian; Zhong, Bao; Liu, Ruijie; Wu, Yan; Chan, Zhulong

    2016-01-01

    Drought stress is one of the disadvantageous environmental conditions for plant growth and reproduction. Given the importance of abscisic acid (ABA) to plant growth and abiotic stress responses, identification of novel components involved in ABA signalling transduction is critical. In this study, we screened numerous Arabidopsis thaliana mutants by seed germination assay and identified a mutant mlp43 (major latex protein-like 43) with decreased ABA sensitivity in seed germination. The mlp43 mutant was sensitive to drought stress while the MLP43-overexpressed transgenic plants were drought tolerant. The tissue-specific expression pattern analysis showed that MLP43 was predominantly expressed in cotyledons, primary roots and apical meristems, and a subcellular localization study indicated that MLP43 was localized in the nucleus and cytoplasm. Physiological and biochemical analyses indicated that MLP43 functioned as a positive regulator in ABA- and drought-stress responses in Arabidopsis through regulating water loss efficiency, electrolyte leakage, ROS levels, and as well as ABA-responsive gene expression. Moreover, metabolite profiling analysis indicated that MLP43 could modulate the production of primary metabolites under drought stress conditions. Reconstitution of ABA signalling components in Arabidopsis protoplasts indicated that MLP43 was involved in ABA signalling transduction and acted upstream of SnRK2s by directly interacting with SnRK2.6 and ABF1 in a yeast two-hybrid assay. Moreover, ABA and drought stress down-regulated MLP43 expression as a negative feedback loop regulation to the performance of MLP43 in ABA and drought stress responses. Therefore, this study provided new insights for interpretation of physiological and molecular mechanisms of Arabidopsis MLP43 mediating ABA signalling transduction and drought stress responses.

  14. Involvement of abscisic acid in the response of Medicago sativa plants in symbiosis with Sinorhizobium meliloti to salinity.

    Science.gov (United States)

    Palma, F; López-Gómez, M; Tejera, N A; Lluch, C

    2014-06-01

    Legumes are classified as salt-sensitive crops with their productivity particularly affected by salinity. Abcisic acid (ABA) plays an important role in the response to environmental stresses as signal molecule which led us to study its role in the response of nitrogen fixation and antioxidant metabolism in root nodules of Medicago sativa under salt stress conditions. Adult plants inoculated with Sinorhizobium meliloti were treated with 1 μM and 10 μM ABA two days before 200 mM salt addition. Exogenous ABA together with the salt treatment provoked a strong induction of the ABA content in the nodular tissue which alleviated the inhibition induced by salinity in the plant growth and nitrogen fixation. Antioxidant enzymes superoxide dismutase (SOD), catalase (CAT) and glutathione reductase (GR) were induced by ABA pre-treatments under salt stress conditions which together with the reduction of the lipid peroxidation, suggest a role for ABA as signal molecule in the activation of the nodular antioxidant metabolism. Interaction between ABA and polyamines (PAs), described as anti-stress molecules, was studied being detected an induction of the common polyamines spermidine (Spd) and spermine (Spm) levels by ABA under salt stress conditions. In conclusion, ABA pre-treatment improved the nitrogen fixation capacity under salt stress conditions by the induction of the nodular antioxidant defenses which may be mediated by the common PAs Spd and Spm that seems to be involved in the anti-stress response induced by ABA.

  15. Tomato ABSCISIC ACID STRESS RIPENING (ASR) gene family revisited.

    Science.gov (United States)

    Golan, Ido; Dominguez, Pia Guadalupe; Konrad, Zvia; Shkolnik-Inbar, Doron; Carrari, Fernando; Bar-Zvi, Dudy

    2014-01-01

    Tomato ABSCISIC ACID RIPENING 1 (ASR1) was the first cloned plant ASR gene. ASR orthologs were then cloned from a large number of monocot, dicot and gymnosperm plants, where they are mostly involved in response to abiotic (drought and salinity) stress and fruit ripening. The tomato genome encodes five ASR genes: ASR1, 2, 3 and 5 encode low-molecular-weight proteins (ca. 110 amino acid residues each), whereas ASR4 encodes a 297-residue polypeptide. Information on the expression of the tomato ASR gene family is scarce. We used quantitative RT-PCR to assay the expression of this gene family in plant development and in response to salt and osmotic stresses. ASR1 and ASR4 were the main expressed genes in all tested organs and conditions, whereas ASR2 and ASR3/5 expression was two to three orders of magnitude lower (with the exception of cotyledons). ASR1 is expressed in all plant tissues tested whereas ASR4 expression is limited to photosynthetic organs and stamens. Essentially, ASR1 accounted for most of ASR gene expression in roots, stems and fruits at all developmental stages, whereas ASR4 was the major gene expressed in cotyledons and young and fully developed leaves. Both ASR1 and ASR4 were expressed in flower organs, with ASR1 expression dominating in stamens and pistils, ASR4 in sepals and petals. Steady-state levels of ASR1 and ASR4 were upregulated in plant vegetative organs following exposure to salt stress, osmotic stress or the plant abiotic stress hormone abscisic acid (ABA). Tomato plants overexpressing ASR1 displayed enhanced survival rates under conditions of water stress, whereas ASR1-antisense plants displayed marginal hypersensitivity to water withholding.

  16. Tomato ABSCISIC ACID STRESS RIPENING (ASR gene family revisited.

    Directory of Open Access Journals (Sweden)

    Ido Golan

    Full Text Available Tomato ABSCISIC ACID RIPENING 1 (ASR1 was the first cloned plant ASR gene. ASR orthologs were then cloned from a large number of monocot, dicot and gymnosperm plants, where they are mostly involved in response to abiotic (drought and salinity stress and fruit ripening. The tomato genome encodes five ASR genes: ASR1, 2, 3 and 5 encode low-molecular-weight proteins (ca. 110 amino acid residues each, whereas ASR4 encodes a 297-residue polypeptide. Information on the expression of the tomato ASR gene family is scarce. We used quantitative RT-PCR to assay the expression of this gene family in plant development and in response to salt and osmotic stresses. ASR1 and ASR4 were the main expressed genes in all tested organs and conditions, whereas ASR2 and ASR3/5 expression was two to three orders of magnitude lower (with the exception of cotyledons. ASR1 is expressed in all plant tissues tested whereas ASR4 expression is limited to photosynthetic organs and stamens. Essentially, ASR1 accounted for most of ASR gene expression in roots, stems and fruits at all developmental stages, whereas ASR4 was the major gene expressed in cotyledons and young and fully developed leaves. Both ASR1 and ASR4 were expressed in flower organs, with ASR1 expression dominating in stamens and pistils, ASR4 in sepals and petals. Steady-state levels of ASR1 and ASR4 were upregulated in plant vegetative organs following exposure to salt stress, osmotic stress or the plant abiotic stress hormone abscisic acid (ABA. Tomato plants overexpressing ASR1 displayed enhanced survival rates under conditions of water stress, whereas ASR1-antisense plants displayed marginal hypersensitivity to water withholding.

  17. Four Arabidopsis AREB/ABF transcription factors function predominantly in gene expression downstream of SnRK2 kinases in abscisic acid signalling in response to osmotic stress.

    Science.gov (United States)

    Yoshida, Takuya; Fujita, Yasunari; Maruyama, Kyonoshin; Mogami, Junro; Todaka, Daisuke; Shinozaki, Kazuo; Yamaguchi-Shinozaki, Kazuko

    2015-01-01

    Under osmotic stress conditions such as drought and high salinity, the plant hormone abscisic acid (ABA) plays important roles in stress-responsive gene expression mainly through three bZIP transcription factors, AREB1/ABF2, AREB2/ABF4 and ABF3, which are activated by SNF1-related kinase 2s (SnRK2s) such as SRK2D/SnRK2.2, SRK2E/SnRK2.6 and SRK2I/SnRK2.3 (SRK2D/E/I). However, since the three AREB/ABFs are crucial, but not exclusive, for the SnRK2-mediated gene expression, transcriptional pathways governed by SRK2D/E/I are not fully understood. Here, we show that a bZIP transcription factor, ABF1, is a functional homolog of AREB1, AREB2 and ABF3 in ABA-dependent gene expression in Arabidopsis. Despite lower expression levels of ABF1 than those of the three AREB/ABFs, the areb1 areb2 abf3 abf1 mutant plants displayed increased sensitivity to drought and decreased sensitivity to ABA in primary root growth compared with the areb1 areb2 abf3 mutant. Genome-wide transcriptome analyses revealed that expression of downstream genes of SRK2D/E/I, which include many genes functioning in osmotic stress responses and tolerance such as transcription factors and LEA proteins, was mostly impaired in the quadruple mutant. Thus, these results indicate that the four AREB/ABFs are the predominant transcription factors downstream of SRK2D/E/I in ABA signalling in response to osmotic stress during vegetative growth.

  18. Regulation of the abscisic acid response by protein phosphatase 2C-interacting proteins ABP7 and ABP9 in Arabidopsis thaliana

    OpenAIRE

    Ma-Lauer, Yue

    2011-01-01

    The protein phosphatases 2C ABI1 and ABI2 are negative regulators in signal transduction of the phytohormone abscisic acid (ABA). The aim of this work is to characterize two homologous proteins ABP7 and ABP9, which were identified as interacting partners of ABI2 in the yeast two-hybrid system. In protoplasts, ABP7 and ABP9 interacted with both ABI1 and ABI2 in the nucleus and the cytosol. Overexpression of ABP7 and ABP9 resulted in dramatic inductions of ABA-induced gene expression in div...

  19. Calcium partitioning and allocation and blossom-end rot development in tomato plants in response to whole-plant and fruit-specific abscisic acid treatments.

    Science.gov (United States)

    Tonetto de Freitas, Sergio; McElrone, Andrew J; Shackel, Kenneth A; Mitcham, Elizabeth J

    2014-01-01

    The mechanisms regulating Ca(2+) partitioning and allocation in plants and fruit remain poorly understood. The objectives of this study were to determine Ca(2+) partitioning and allocation in tomato plants and fruit in response to whole-plant and fruit-specific abscisic acid (ABA) treatments, as well as to analyse the effect of changes in Ca(2+) partitioning and allocation on fruit susceptibility to the Ca(2+) deficiency disorder blossom-end rot (BER) under water stress conditions. Tomato plants of the cultivar Ace 55 (Vf) were grown in a greenhouse and exposed to low Ca(2+) conditions during fruit growth and development. Starting 1 day after pollination (DAP), the following treatments were initiated: (i) whole plants were sprayed weekly with deionized water (control) or (ii) with 500mg l(-1) ABA; or fruit on each plant were dipped weekly (iii) in deionized water (control) or (iv) in 500mg l(-1) ABA. At 15 DAP, BER was completely prevented by whole-plant or fruit-specific ABA treatments, whereas plants or fruit treated with water had 16-19% BER incidence. At 30 DAP, BER was prevented by the whole-plant ABA treatment, whereas fruit dipped in ABA had a 16% and water-treated plants or fruit had a 36-40% incidence of BER. The results showed that spraying the whole plant with ABA increases xylem sap flow and Ca(2+) movement into the fruit, resulting in higher fruit tissue and water-soluble apoplastic Ca(2+) concentrations that prevent BER development. Although fruit-specific ABA treatment had no effect on xylem sap flow rates or Ca(2+) movement into the fruit, it increased fruit tissue water-soluble apoplastic Ca(2+) concentrations and reduced fruit susceptibility to BER to a lesser extent.

  20. Comparative study of putative 9-cis-epoxycarotenoid dioxygenase and abscisic acid accumulation in the responses of Sunki mandarin and Rangpur lime to water deficit.

    Science.gov (United States)

    Neves, D M; Filho, M A Coelho; Bellete, B S; Silva, M F G F; Souza, D T; Dos S Soares Filho, W; Costa, M G C; Gesteira, A S

    2013-09-01

    Abscisic acid is a plant hormone that participates in essential plant physiological processes, especially during adaptation to many environmental stresses, such as water deficit. The relationship between ABA accumulation and the expression of putative carotenoid cleavage dioxygenase (CCD) genes was investigated in the pot-cultivated leaves and roots of the 'Rangpur' lime and 'Sunki Maravilha' mandarin plants. Transpiration, stomatal resistance and leaf growth were evaluated when these genotypes were subjected to continuous water deficit. Under water deficit conditions, the 'Rangpur' lime extracts used greater amounts of water when compared to the 'Sunki Maravilha' plants, which reached the greatest stomatal resistance 5 days before 'Rangpur' lime. When subjected to water deficit, the roots and leaves of 'Sunki Maravilha' showed a progressive increase in ABA accumulation; however, in 'Rangpur' lime, alternations between high and low ABA concentrations were observed. These results suggest a retroactive feeding regulation by ABA. In 'Rangpur' lime the NCED2, NCED3 and CCD4a genes were expressed at the highest levels in the roots, and NCED5 was highly expressed in the leaves; in 'Sunki Maravilha', the NCED2 and NCED5 genes were most highly expressed in the roots, and NCED2 was most highly expressed in the leaves. However, for both genotypes, the transcription of these genes only correlated with ABA accumulation during the most severe water deficit conditions. The 'Rangpur' lime behaved as a vigorous rootstock; the leaf growth remained unaltered even when water was scarce. However, 'Sunki Maravilha' adaptation was based on the equilibrium of the response between the root and the aerial tissues due to water restriction. The use of the Sunki mandarin in combination with a scion with similar characteristics as its own, which responds to water deficit stress by accumulating ABA in the leaves, may display good drought tolerance under field conditions.

  1. [Tissue culture of medicinal plant and abscisic acid].

    Science.gov (United States)

    Fang, Hui-Yong; Zhu, Hong; Yao, Jian-Xun; Jia, Cai-Feng; Shan, Gao-Wei; Li, Min-Hui

    2013-01-01

    Abscisic acid (ABA) plays a key role in many physiological processes of plants, and it was also applied to fields of medicinal plant biotechnology. The article presents a review of some recent application of ABA in enhancing the production of secondary metabolites of medicinal plants, improving the in vitro conservation in medicinal plant tissue culture system.

  2. Abscisic acid and assimilate partitioning during seed development.

    NARCIS (Netherlands)

    Bruijn, de S.M.

    1993-01-01

    This thesis describes the influence of abscisic acid (ABA) on the transport of assimilates to seeds and the deposition of reserves in seeds. It is well-known from literature that ABA accumulates in seeds during development, and that ABA concentrations in seeds correlate rather well with seed size an

  3. Genetic Analysis of Ca2+ Priming in Arabidopsis Guard Cell Stomatal Closure in Response to the Drought Hormone Abscisic Acid

    Energy Technology Data Exchange (ETDEWEB)

    Stephan, Aaron B.

    2014-11-30

    A primary objective of modern agriculture and biofuel production is to utilize arable land to its fullest potential. However, sub-optimal growing conditions—arising from abiotic stresses such as drought, soil salinity, low humidity, cold, and heat—reduce crop yield and quality. Optimal yield under both stressed and non-stressed conditions requires the plant to activate coping mechanisms at a level commensurate with the severity of the drought stress. The osmotic sensors and associated regulatory mechanisms that initiate drought- and salt-tolerance responses in plants are largely unknown. This research aimed to identify and characterize these initial sensory components.

  4. Identification and characterization of the abscisic acid (ABA) receptor gene family and its expression in response to hormones in the rubber tree

    Science.gov (United States)

    Guo, Dong; Zhou, Ying; Li, Hui-Liang; Zhu, Jia-Hong; Wang, Ying; Chen, Xiong-Ting; Peng, Shi-Qing

    2017-01-01

    Abscisic acid (ABA) is an essential phytohormone involved in diverse physiological processes. Although genome-wide analyses of the ABA receptor PYR/PYL/RCAR (PYL) protein/gene family have been performed in certain plant species, little is known about the ABA receptor protein/gene family in the rubber tree (Hevea brasiliensis). In this study, we identified 14 ABA receptor PYL proteins/genes (designated HbPYL1 through HbPYL14) in the most recent rubber tree genome. A phylogenetic tree was constructed, which demonstrated that HbPYLs can be divided into three subfamilies that correlate well with the corresponding Arabidopsis subfamilies. Eight HbPYLs are highly expressed in laticifers. Five of the eight genes are simultaneously regulated by ABA, jasmonic acid (JA) and ethylene (ET). The identification and characterization of HbPYLs should enable us to further understand the role of ABA signal in the rubber tree. PMID:28332623

  5. The upregulation of thiamine (vitamin B1 biosynthesis in Arabidopsis thaliana seedlings under salt and osmotic stress conditions is mediated by abscisic acid at the early stages of this stress response

    Directory of Open Access Journals (Sweden)

    Rapala-Kozik Maria

    2012-01-01

    Full Text Available Abstract Background Recent reports suggest that vitamin B1 (thiamine participates in the processes underlying plant adaptations to certain types of abiotic and biotic stress, mainly oxidative stress. Most of the genes coding for enzymes involved in thiamine biosynthesis in Arabidopsis thaliana have been identified. In our present study, we examined the expression of thiamine biosynthetic genes, of genes encoding thiamine diphosphate-dependent enzymes and the levels of thiamine compounds during the early (sensing and late (adaptation responses of Arabidopsis seedlings to oxidative, salinity and osmotic stress. The possible roles of plant hormones in the regulation of the thiamine contribution to stress responses were also explored. Results The expression of Arabidopsis genes involved in the thiamine diphosphate biosynthesis pathway, including that of THI1, THIC, TH1 and TPK, was analyzed for 48 h in seedlings subjected to NaCl or sorbitol treatment. These genes were found to be predominantly up-regulated in the early phase (2-6 h of the stress response. The changes in these gene transcript levels were further found to correlate with increases in thiamine and its diphosphate ester content in seedlings, as well as with the enhancement of gene expression for enzymes which require thiamine diphosphate as a cofactor, mainly α-ketoglutarate dehydrogenase, pyruvate dehydrogenase and transketolase. In the case of the phytohormones including the salicylic, jasmonic and abscisic acids which are known to be involved in plant stress responses, only abscisic acid was found to significantly influence the expression of thiamine biosynthetic genes, the thiamine diphosphate levels, as well as the expression of genes coding for main thiamine diphosphate-dependent enzymes. Using Arabidopsis mutant plants defective in abscisic acid production, we demonstrate that this phytohormone is important in the regulation of THI1 and THIC gene expression during salt stress

  6. Changes in abundance of an abscisic acid-responsive, early cysteine-labeled metallothionein transcript during pollen embryogenesis in bread wheat (Triticum aestivum).

    Science.gov (United States)

    Reynolds, T L; Crawford, R L

    1996-12-01

    A clone for an embryoid-abundant, early cysteine-labeled metallothionein (EcMt) gene has been isolated from a wheat pollen embryoid cDNA library. The transcript of this gene was only expressed in embryogenic microspores, pollen embryoids, and developing zygotic embryos of wheat. Accumulation of the EcMt mRNA showed a direct and positive correlation with an increase of the plant hormone, abscisic acid (ABA) in developing pollen embryoids. Treating cultures with an inhibitor of ABA biosynthesis, fluridone, suppressed not only ABA accumulation but also the appearance of the EcMt gene transcript and the ability of microspores to form embryoids. These results suggest that the EcMt gene may act as a molecular marker for pollen embryogenesis because ABA biosynthesis is accompanied by the increased expression of the EcMt transcript that coincides with the differentiation of pollen embryoids in wheat anther cultures.

  7. Abscisic acid controlled sex before transpiration in vascular plants.

    Science.gov (United States)

    McAdam, Scott A M; Brodribb, Timothy J; Banks, Jo Ann; Hedrich, Rainer; Atallah, Nadia M; Cai, Chao; Geringer, Michael A; Lind, Christof; Nichols, David S; Stachowski, Kye; Geiger, Dietmar; Sussmilch, Frances C

    2016-10-26

    Sexual reproduction in animals and plants shares common elements, including sperm and egg production, but unlike animals, little is known about the regulatory pathways that determine the sex of plants. Here we use mutants and gene silencing in a fern species to identify a core regulatory mechanism in plant sexual differentiation. A key player in fern sex differentiation is the phytohormone abscisic acid (ABA), which regulates the sex ratio of male to hermaphrodite tissues during the reproductive cycle. Our analysis shows that in the fern Ceratopteris richardii, a gene homologous to core ABA transduction genes in flowering plants [SNF1-related kinase2s (SnRK2s)] is primarily responsible for the hormonal control of sex determination. Furthermore, we provide evidence that this ABA-SnRK2 signaling pathway has transitioned from determining the sex of ferns to controlling seed dormancy in the earliest seed plants before being co-opted to control transpiration and CO2 exchange in derived seed plants. By tracing the evolutionary history of this ABA signaling pathway from plant reproduction through to its role in the global regulation of plant-atmosphere gas exchange during the last 450 million years, we highlight the extraordinary effect of the ABA-SnRK2 signaling pathway in plant evolution and vegetation function.

  8. Structural basis and functions of abscisic acid receptors PYLs

    Science.gov (United States)

    Zhang, Xing L.; Jiang, Lun; Xin, Qi; Liu, Yang; Tan, Jian X.; Chen, Zhong Z.

    2015-01-01

    Abscisic acid (ABA) plays a key role in many developmental processes and responses to adaptive stresses in plants. Recently, a new family of nucleocytoplasmic PYR/PYL/RCAR (PYLs) has been identified as bona fide ABA receptors. PYLs together with protein phosphatases type-2C (PP2Cs), Snf1 (Sucrose-non-fermentation 1)-related kinases subfamily 2 (SnRK2s) and downstream substrates constitute the core ABA signaling network. Generally, PP2Cs inactivate SnRK2s kinases by physical interaction and direct dephosphorylation. Upon ABA binding, PYLs change their conformations and then contact and inhibit PP2Cs, thus activating SnRK2s. Here, we reviewed the recent progress in research regarding the structures of the core signaling pathways of ABA, including the (+)-ABA, (−)-ABA and ABA analogs pyrabactin as well as 6AS perception by PYLs, SnRK2s mimicking PYLs in binding PP2Cs. PYLs inhibited PP2Cs in both the presence and absence of ABA and activated SnRK2s. The present review elucidates multiple ABA signal perception and transduction by PYLs, which might shed light on how to design small chemical compounds for improving plant performance in the future. PMID:25745428

  9. Abscisic acid and blue light signaling pathways in chloroplast movements in Arabidopsis mesophyll.

    Science.gov (United States)

    Eckstein, Aleksandra; Krzeszowiec, Weronika; Banaś, Agnieszka Katarzyna; Janowiak, Franciszek; Gabryś, Halina

    2016-01-01

    Abscisic acid (ABA) and phototropins act antagonistically to control stomatal movements. Here, we investigated the role of ABA in phototropin-directed chloroplast movements in mesophyll cells of Arabidopsis thaliana. We analyzed the expression of phototropins at mRNA and protein level under the influence of ABA. PHOT1 mRNA level was decreased by ABA in the dark while it was insensitive to ABA in light. PHOT2 mRNA level was independent of the hormone treatment. The levels of phototropin proteins were down-regulated by ABA, both in darkness and light. No impact of exogenous ABA on amplitudes and kinetics of chloroplast movements was detected. Chloroplast responses in wild type Arabidopsis and three mutants, abi4, abi2 (abscisic acid insensitive4, 2) and aba1 (abscisic acid1), were measured to account for endogenous ABA signaling. The chloroplast responses were slightly reduced in abi2 and aba1 mutants in strong light. To further investigate the effect, abi2 and aba1 mutants were supplemented with exogenous ABA. In the aba1 mutant, the reaction was rescued but in abi2 it was unaffected. Our results show that ABA is not directly involved in phototropin-controlled chloroplast responses in mature leaves of Arabidopsis. However, the disturbance of ABA biosynthesis and signaling in mutants affects some elements of the chloroplast movement mechanism. In line with its role as a stress hormone, ABA appears to enhance plant sensitivity to light and promote the chloroplast avoidance response.

  10. Abscisic Acid Signal off the STARTing Block

    Institute of Scientific and Technical Information of China (English)

    Archana Joshi-Saha; Christiane Valon; Jeffrey Leung

    2011-01-01

    The year 2009 marked a real turnaround in our understanding of the mode ot abscisJc acid(ABA)action. Nearly 25 years had elapsed since the first biochemical detection of ABA-binding proteins in the plasmalemma of Vicia guard cells was reported. This recent-and laudable-achievement is owed largely to the discovery of the soluble ABA receptors whose major interacting proteins happen to be some of the most well-established components of earliest steps in ABA signaling. These soluble receptors, with the double name of PYRABACTIN RESISTANCE (PYR)or REGULATORY COM-PONENT OF ABA RECEPTOR (RCAR), are a family of Arabidopsis proteins of about 150-200 amino acids that share a con-served START domain. The ABA signal transduction circuitry under non-stress conditions is muted by the ciade A protein phosphatases 2C (PP2C)(notably HAB1, ABI1, and ABI2). During the initial steps of ABA signaling, the binding of the hor-mone to the receptor induces a conformational change in the latter that allows it to sequester the PP2Cs. This excludes them from the negative regulation of the downstream ABA-activated kinases (OST1/SnRK2.6/SRK2E, SnRK2.2, and SnRK2.3), thus unleashing the pathway by freeing them to phosphorylate downstream targets that now include several b-ZIP transcription factors, ion channels (SLAC1, KAT1), and a NADPH oxidase (AtrbohF). The discovery of this family of soluble receptors and the rich insight already gained from structural studies of their complexes with different isoforms of ABA, PP2C, and the synthetic agonist pyrabactin lay the foundation towards rational design of chemical switches that can bolster drought hardiness in plants.

  11. Action of Abscisic Acid on Auxin Transport and its Relation to Phototropism

    DEFF Research Database (Denmark)

    Naqvi, S. M.; Engvild, Kjeld Christensen

    1974-01-01

    The action of abscisic acid on the kinetics of auxin transport through Zea mays L. (cv. Goudster) coleoptiles has been investigated. Abscisic acid applied simultaneously with indoleacetic acid-2-14C in the donor block reduced the transport intensity without materially affecting the basipetal...

  12. Abscisic acid and assimilate partitioning during seed development.

    OpenAIRE

    Bruijn, de, NG Dick

    1993-01-01

    This thesis describes the influence of abscisic acid (ABA) on the transport of assimilates to seeds and the deposition of reserves in seeds. It is well-known from literature that ABA accumulates in seeds during development, and that ABA concentrations in seeds correlate rather well with seed size and seed growth rates. However, since ABA is at least partly synthesized in the leaves and transported to the seeds via the phloem, a correlation between ABA levels and growth rate can easily be expl...

  13. In vitro reconstitution of an abscisic acid signalling pathway

    KAUST Repository

    Fujii, Hiroaki

    2009-11-18

    The phytohormone abscisic acid (ABA) regulates the expression of many genes in plants; it has critical functions in stress resistance and in growth and development. Several proteins have been reported to function as ABA receptors, and many more are known to be involved in ABA signalling. However, the identities of ABA receptors remain controversial and the mechanism of signalling from perception to downstream gene expression is unclear. Here we show that by combining the recently identified ABA receptor PYR1 with the type 2C protein phosphatase (PP2C) ABI1, the serine/threonine protein kinase SnRK2.6/OST1 and the transcription factor ABF2/AREB1, we can reconstitute ABA-triggered phosphorylation of the transcription factor in vitro. Introduction of these four components into plant protoplasts results in ABA-responsive gene expression. Protoplast and test-tube reconstitution assays were used to test the function of various members of the receptor, protein phosphatase and kinase families. Our results suggest that the default state of the SnRK2 kinases is an autophosphorylated, active state and that the SnRK2 kinases are kept inactive by the PP2Cs through physical interaction and dephosphorylation. We found that in the presence of ABA, the PYR/PYL (pyrabactin resistance 1/PYR1-like) receptor proteins can disrupt the interaction between the SnRK2s and PP2Cs, thus preventing the PP2C-mediated dephosphorylation of the SnRK2s and resulting in the activation of the SnRK2 kinases. Our results reveal new insights into ABA signalling mechanisms and define a minimal set of core components of a complete major ABA signalling pathway. © 2009 Macmillan Publishers Limited. All rights reserved.

  14. Abscisic acid ameliorates the systemic sclerosis fibroblast phenotype in vitro

    Energy Technology Data Exchange (ETDEWEB)

    Bruzzone, Santina, E-mail: santina.bruzzone@unige.it [Department of Experimental Medicine, Section of Biochemistry, University of Genova, Viale Benedetto XV 1, 16132 Genova (Italy); Centre of Excellence for Biomedical Research, University of Genova, Viale Benedetto XV 9, 16132 Genova (Italy); Advanced Biotechnology Center, Largo Rosanna Benzi 10, 16132 Genova (Italy); Battaglia, Florinda [Centre of Excellence for Biomedical Research, University of Genova, Viale Benedetto XV 9, 16132 Genova (Italy); Mannino, Elena [Department of Experimental Medicine, Section of Biochemistry, University of Genova, Viale Benedetto XV 1, 16132 Genova (Italy); Parodi, Alessia [Centre of Excellence for Biomedical Research, University of Genova, Viale Benedetto XV 9, 16132 Genova (Italy); Fruscione, Floriana [Department of Experimental Medicine, Section of Biochemistry, University of Genova, Viale Benedetto XV 1, 16132 Genova (Italy); Advanced Biotechnology Center, Largo Rosanna Benzi 10, 16132 Genova (Italy); Basile, Giovanna [Department of Experimental Medicine, Section of Biochemistry, University of Genova, Viale Benedetto XV 1, 16132 Genova (Italy); Salis, Annalisa; Sturla, Laura [Department of Experimental Medicine, Section of Biochemistry, University of Genova, Viale Benedetto XV 1, 16132 Genova (Italy); Centre of Excellence for Biomedical Research, University of Genova, Viale Benedetto XV 9, 16132 Genova (Italy); Negrini, Simone; Kalli, Francesca; Stringara, Silvia [Centre of Excellence for Biomedical Research, University of Genova, Viale Benedetto XV 9, 16132 Genova (Italy); Filaci, Gilberto [Centre of Excellence for Biomedical Research, University of Genova, Viale Benedetto XV 9, 16132 Genova (Italy); Department of Internal Medicine, Viale Benedetto XV 6, 16132 Genova (Italy); and others

    2012-05-25

    Highlights: Black-Right-Pointing-Pointer ABA is an endogenous hormone in humans, regulating different cell responses. Black-Right-Pointing-Pointer ABA reverts some of the functions altered in SSc fibroblasts to a normal phenotype. Black-Right-Pointing-Pointer UV-B irradiation increases ABA content in SSc cultures. Black-Right-Pointing-Pointer SSc fibroblasts could benefit from exposure to ABA and/or to UV-B. -- Abstract: The phytohormone abscisic acid (ABA) has been recently identified as an endogenous hormone in humans, regulating different cell functions, including inflammatory processes, insulin release and glucose uptake. Systemic sclerosis (SSc) is a chronic inflammatory disease resulting in fibrosis of skin and internal organs. In this study, we investigated the effect of exogenous ABA on fibroblasts obtained from healthy subjects and from SSc patients. Migration of control fibroblasts induced by ABA was comparable to that induced by transforming growth factor-{beta} (TGF-{beta}). Conversely, migration toward ABA, but not toward TGF-{beta}, was impaired in SSc fibroblasts. In addition, ABA increased cell proliferation in fibroblasts from SSc patients, but not from healthy subjects. Most importantly, presence of ABA significantly decreased collagen deposition by SSc fibroblasts, at the same time increasing matrix metalloproteinase-1 activity and decreasing the expression level of tissue inhibitor of metalloproteinase (TIMP-1). Thus, exogenously added ABA appeared to revert some of the functions altered in SSc fibroblasts to a normal phenotype. Interestingly, ABA levels in plasma from SSc patients were found to be significantly lower than in healthy subjects. UV-B irradiation induced an almost 3-fold increase in ABA content in SSc cultures. Altogether, these results suggest that the fibrotic skin lesions in SSc patients could benefit from exposure to high(er) ABA levels.

  15. The action of exogenous abscisic and gibberellic acids on gene expression in germinating castor beans.

    Science.gov (United States)

    Dommes, J; Northcote, D H

    1985-09-01

    Exogenously applied abscisic acid inhibits isocitrate-lyase activity of the endosperm during germination of castor-bean seeds. Amounts of isocitrate-lyase mRNA have been estimated by immunoprecipitation of in-vitro-translated polypeptide products. Exogenous abscisic acid leads to an inhibition of isocitrate lyase-mRNA accumulation. A large proportion of this effect of the growth factor may be accounted for by its action in inhibiting the overall accumulation of ribosomal RNA and total mRNA. However, the effect of abscisic acid on protein synthesis is not general, as the production of some mRNAs was stimulated. The major mRNA stored in the dry seed, coding for a 25600-Mr polypeptide that normally disappears within the first 12 h of germination, exhibited high levels in abscisic-acid-treated endosperms throughout the germination period. Three complementary DNA clones, of which two clones are complementary to isocitrate lyase, have been used to measure levels of transcripts during seed germination. The accumulation of both transcripts was inhibited by exogenous abscisic acid. The data strongly indicate that the action of abscisic acid on isocitrate lyase synthesis is either to inhibit the transcription, or to increase the transcript turnover. Exogenous gibberellic acid is able to counteract the inhibitory effects of abscisic acid.

  16. An Update on Abscisic Acid Signaling in Plants and More...

    Institute of Scientific and Technical Information of China (English)

    Aleksandra Wasilewska; Florina Vlad; Caroline Sirichandra; Yulia Redko; Fabien Jammes; Christiane Valon; Nicolas Frei dit Frey; Jeffrey Leung

    2008-01-01

    The mode of abscisic acid (ABA) action,and its relations to drought adaptive responses in particular,has been a captivating area of plant hormone research for much over a decade.The hormone triggers stomatal closure to limit water loss through transpiration,as well as mobilizes a battery of genes that presumably serve to protect the cells from the ensuing oxidative damage in prolonged stress.The signaling network orchestrating these various responses is,however,highly complex.This review summarizes several significant advances made within the last few years.The biosynthetic pathway of the hormone is now almost completely elucidated,with the latest identification of the ABA4 gene encoding a neoxanthin synthase,which seems essential for de novo ABA biosynthesis during water stress.This leads to the interesting question on how ABA is then delivered to perception sites.In this respect,regulated transport has attracted renewed focus by the unexpected finding of a shoot-to-root translocation of ABA during drought response,and at the cellular level,by the identification of a β-galactosidase that releases biologically active ABA from inactive ABA-glucose ester.Surprising candidate ABA receptors were also identified in the form of the Flowering Time Control Protein A (FCA)and the Chloroplastic Magnesium Protoporphyrin-IX Chelatase H subunit (CHLH) in chloroplast-nucleus communication,both of which have been shown to bind ABA in vitro.On the other hand,the protein(s) corresponding to the physiologically detectable cell-surface ABA receptor(s) is (are) still not known with certainty.Genetic and physiological studies based on the guard cell have reinforced the central importance of reversible phosphorylation in modulating rapid ABA responses.Sucrose Non-Fermenting Related Kinases (SnRK),Calcium-Dependent Protein Kinases (CDPK),Protein Phosphatases (PP) of the 2C and 2A classes figure as prominent regulators in this single-cell model.Identifying their direct in vivo targets of

  17. Effects of Abscisic Acid and of Hydrostatic Pressure Gradient on Water Movement through Excised Sunflower Roots.

    Science.gov (United States)

    Glinka, Z

    1977-05-01

    The effect of abscisic acid on the exudation rate from decapitated roots of sunflower plants (Helianthus annuus L.) was investigated in the presence and absence of an imposed hydrostatic pressure gradient. The magnitude of the abscisic acid effect was constant even when suctions up to 60 cm Hg were applied to the cut stumps.When roots were bathed in a THO-labeled nutrient solution, the course of the appearance of radioactivity in the exudate, expressed as a function of exudate volume, was not affected by abscisic acid treatment but was strongly speeded up by applying suction.The implications of those findings with regard to the water pathway through the root and the location of the abscisic acid effect are discussed.

  18. The role of cis-carotenoids in abscisic acid biosynthesis.

    Science.gov (United States)

    Parry, A D; Babiano, M J; Horgan, R

    1990-08-01

    Evidence has been obtained which is consistent with 9'-cis-neoxanthin being a major precursor of abscisic acid (ABA) in higher plants. A mild, rapid procedure was developed for the extraction and analysis of carotenoids from a range of tissues. Once purified the carotenoids were identified from their light-absorbance properties, reactions with dilute acid, high-performance liquid chromatography Rts, mass spectra and the quasiequilibria resulting from iodine-catalysed or chlorophyllsensitised photoisomerisation. Two possible ABA precursors, 9'-cis-neoxanthin and 9-cis-violaxanthin, were identified in extracts of light-grown and etiolated leaves (of Lycopersicon esculentum, Phaseolus vulgaris, Vicia faba, Pisum sativum, Cicer arietinum, Zea mays, Nicotiana plumbaginifolia, Plantago lanceolata and Digitalis purpurea), and roots of light-grown and etiolated plants (Lycopersicon, Phaseolus and Zea). The 9,9'-di-cisisomer of violaxanthin was synthesised but its presence was not detected in any extracts. Levels of 9'-cis-neoxanthin and all-trans-violaxanthin were between 20- to 100-fold greater than those of ABA in light-grown leaves. The levels of 9-cis-violaxanthin were similar to those of ABA but unaffected by water stress. Etiolated Phaseolus leaves contained reduced amounts of carotenoids (15-20% compared with light-grown leaves) but retained the ability to synthesise large amounts of ABA. The amounts of ABA synthesised, measured as increases in ABA and its metabolites phaseic acid and dihydrophaseic acid, were closely matched by decreases in the levels of 9'-cis-neoxanthin and all-trans-violaxanthin. In etiolated seedlings grown on 50% D2O, deuterium incorporation into ABA was similar to that into the xanthophylls. Relative levels of carotenoids in roots and light-grown and etiolated leaves of the ABA-deficient mutants, notabilis, flacca and sitiens were the same as those found in wild-type tomato tissues.

  19. Interactions between red light, abscisic acid, and calcium in gravitropism

    Science.gov (United States)

    Leopold, A. C.; LaFavre, A. K.

    1989-01-01

    The effect of red light on orthogravitropism of Merit corn (Zea mays L.) roots has been attributed to its effects on the transduction phase of gravitropism (AC Leopold, SH Wettlaufer [1988] Plant Physiol 87:803-805). In an effort to characterize the orthogravitropic transduction system, comparative experiments have been carried out on the effects of red light, calcium, and abscisic acid (ABA). The red light effect can be completely satisfied with added ABA (100 micromolar) or with osmotic shock, which is presumed to increase endogenous ABA. The decay of the red light effect is closely paralleled by the decay of the ABA effect. ABA and exogenous calcium show strong additive effects when applied to either Merit or a line of corn which does not require red light for orthogravitropism. Measurements of the ABA content show marked increases in endogenous ABA in the growing region of the roots after red light. The interpretation is offered that red light or ABA may serve to increase the cytoplasmic concentrations of calcium, and that this may be an integral part of orthogravitropic transduction.

  20. Abscisic acid enhances resistance to Alternaria solani in tomato seedlings.

    Science.gov (United States)

    Song, Weiwei; Ma, Xinrong; Tan, Hong; Zhou, Jinyan

    2011-07-01

    The plant hormone abscisic acid (ABA) is an important regulator in many aspects of plant growth and development, as well as stress resistance. Here, we investigated the effects of exogenous ABA application on the interaction between tomato (Solanum lycopersicon L.) and Alternaria solani (early blight). Foliar spraying of 7.58 μM ABA was effective in reducing disease severity in tomato plants. Previously, increased activities of phenylalanine ammonia-lyase (PAL), polyphenol oxidase (PPO) and peroxidase (POD) were observed in exogenous ABA-treated tomato leaves. Moreover, these enzyme activities were maintained at higher levels in ABA-pretreated and A. solani challenged tomato plants. Tomato defense genes, such as PR1, β-1, 3-glucanase (GLU), PPO, POD, and superoxide dismutase (SOD), were rapidly and significantly up-regulated by exogenous ABA treatment. Furthermore, a subsequent challenge of ABA-pretreated plants with the pathogen A. solani resulted in higher expression of defense genes, compared to water-treated or A. solani inoculated plants. Therefore, our results suggest that exogenous ABA could enhance disease resistance against A. solani infection in tomato through the activation of defense genes and via the enhancement of defense-related enzymatic activities.

  1. Abscisic Acid Biosynthesis in Leaves and Roots of Xanthium strumarium.

    Science.gov (United States)

    Creelman, R A; Gage, D A; Stults, J T; Zeevaart, J A

    1987-11-01

    RESEARCH ON THE BIOSYNTHESIS OF ABSCISIC ACID (ABA) HAS FOCUSED PRIMARILY ON TWO PATHWAYS: (a) the direct pathway from farnesyl pyrophosphate, and (b) the indirect pathway involving a carotenoid precursor. We have investigated which biosynthetic pathway is operating in turgid and stressed Xanthium leaves, and in stressed Xanthium roots using long-term incubations in (18)O(2). It was found that in stressed leaves three atoms of (18)O from (18)O(2) are incorporated into the ABA molecule, and that the amount of (18)O incorporated increases with time. One (18)O atom is incorporated rapidly into the carboxyl group of ABA, whereas the other two atoms are very slowly incorporated into the ring oxygens. The fourth oxygen atom in the carboxyl group of ABA is derived from water. ABA from stressed roots of Xanthium incubated in (18)O(2) shows a labeling pattern similar to that of ABA in stressed leaves, but with incorporation of more (18)O into the tertiary hydroxyl group at C-1' after 6 and 12 hours than found in ABA from stressed leaves. It is proposed that the precursors to stress-induced ABA are xanthophylls, and that a xanthophyll lacking an oxygen function at C-6 (carotenoid numbering scheme) plays a crucial role in ABA biosynthesis in Xanthium roots. In turgid Xanthium leaves, (18)O is incorporated into ABA to a much lesser extent than it is in stressed leaves, whereas exogenously applied (14)C-ABA is completely catabolized within 48 hours. This suggests that ABA in turgid leaves is either (a) made via a biosynthetic pathway which is different from the one in stressed leaves, or (b) has a half-life on the order of days as compared with a half-life of 15.5 hours in water-stressed Xanthium leaves. Phaseic acid showed a labeling pattern similar to that of ABA, but with an additional (18)O incorporated during 8'-hydroxylation of ABA to phaseic acid.

  2. Effects of mechanical stress or abscisic acid on growth, water status and leaf abscisic acid content of eggplant seedlings

    Science.gov (United States)

    Latimer, J. G.; Mitchell, C. A.

    1988-01-01

    Container-grown eggplant (Solanum melongena L. var esculentum Nees. 'Burpee's Black Beauty') seedlings were conditioned with brief, periodic mechanical stress or abscisic acid (ABA) in a greenhouse prior to outdoor exposure. Mechanical stress consisted of seismic (shaking) or thigmic (stem flexing) treatment. Exogenous ABA (10(-3) or 10(-4)M) was applied as a soil drench 3 days prior to outdoor transfer. During conditioning, only thigmic stress reduced stem elongation and only 10(-3) M ABA reduced relative growth rate (RGR). Both conditioning treatments increased leaf specific chlorophyll content, but mechanical stress did not affect leaf ABA content. Outdoor exposure of unconditioned eggplant seedlings decreased RGR and leaf-specific chlorophyll content, but tended to increase leaf ABA content relative to that of plants maintained in the greenhouse. Conditioning did not affect RGR of plants subsequently transferred outdoors, but did reduce stem growth. Seismic stress applied in the greenhouse reduced dry weight gain by plants subsequently transferred outdoors. Mechanical stress treatments increased leaf water potential by 18-25% relative to that of untreated plants.

  3. 种子萌发过程中响应脱落酸与赤霉素的蛋白质组变化研究进展%Research Advances on Abscisic Acid and Gibberellin Responsive Proteomics during Seed Germination

    Institute of Scientific and Technical Information of China (English)

    刘静静; 戴绍军

    2012-01-01

    蛋白质组学技术平台为探究激素功能应答蛋白质提供了有效手段。目前通过蛋白质组学方法已经鉴定出水稻(Oryzasativa)、欧洲山毛榉(Fagus sylvatica)、挪威槭(Acer platanoides)等多个物种种子萌发过程中ABA-和GA-应答蛋白质。综述了种子萌发过程中响应脱落酸和赤霉素的蛋白质组变化相关研究的进展,包括与转录、蛋白质降解、活性氧清除、能量代谢等相关的蛋白质,以及其他代谢相关的蛋白质.以期为揭示种子萌发过程中的激素应答调控机制提供参考。%Proteomies technology platform provides an effective method for exploring hormone-responsive proteins.Recently,many ABA-and GA-responsive proteins upon seed germination have been identified in rice (Oryza s ativa), European been (Fagus sylvatica), Norway maple (Acer platanoides )and other species.Research advances on abscisic acid-and gibberellin-responsive proteomics during seed germination were reviewed, including proteomics related with transcription,protein degradation and degradation, energy metabolism, and other related proteomics, so as to provide references for reveal regulation mechanism of hormones response during seed germination.

  4. Abscisic acid and sucrose regulate tomato and strawberry fruit ripening through the abscisic acid-stress-ripening transcription factor.

    Science.gov (United States)

    Jia, Haifeng; Jiu, Songtao; Zhang, Cheng; Wang, Chen; Tariq, Pervaiz; Liu, Zhongjie; Wang, Baoju; Cui, Liwen; Fang, Jinggui

    2016-10-01

    Although great progress has been made towards understanding the role of abscisic acid (ABA) and sucrose in fruit ripening, the mechanisms underlying the ABA and sucrose signalling pathways remain elusive. In this study, transcription factor ABA-stress-ripening (ASR), which is involved in the transduction of ABA and sucrose signalling pathways, was isolated and analysed in the nonclimacteric fruit, strawberry and the climacteric fruit, tomato. We have identified four ASR isoforms in tomato and one in strawberry. All ASR sequences contained the ABA stress- and ripening-induced proteins and water-deficit stress-induced proteins (ABA/WDS) domain and all ASR transcripts showed increased expression during fruit development. The expression of the ASR gene was influenced not only by sucrose and ABA, but also by jasmonic acid (JA) and indole-3-acetic acid (IAA), and these four factors were correlated with each other during fruit development. ASR bound the hexose transporter (HT) promoter, which contained a sugar box that activated downstream gene expression. Overexpression of the ASR gene promoted fruit softening and ripening, whereas RNA interference delayed fruit ripening, as well as affected fruit physiological changes. Change in ASR gene expression influenced the expression of several ripening-related genes such as CHS, CHI, F3H, DFR, ANS, UFGT, PG, PL, EXP1/2, XET16, Cel1/2 and PME. Taken together, this study may provide new evidence on the important role of ASR in cross-signalling between ABA and sucrose to regulate tomato and strawberry fruit ripening. The findings of this study also provide new insights into the regulatory mechanism underlying fruit development.

  5. UDP-glucosyltransferase71c5, a major glucosyltransferase, mediates abscisic acid homeostasis in Arabidopsis.

    Science.gov (United States)

    Liu, Zhen; Yan, Jin-Ping; Li, De-Kuan; Luo, Qin; Yan, Qiujie; Liu, Zhi-Bin; Ye, Li-Ming; Wang, Jian-Mei; Li, Xu-Feng; Yang, Yi

    2015-04-01

    Abscisic acid (ABA) plays a key role in plant growth and development. The effect of ABA in plants mainly depends on its concentration, which is determined by a balance between biosynthesis and catabolism of ABA. In this study, we characterize a unique UDP-glucosyltransferase (UGT), UGT71C5, which plays an important role in ABA homeostasis by glucosylating ABA to abscisic acid -: glucose ester (GE) in Arabidopsis (Arabidopsis thaliana). Biochemical analyses show that UGT71C5 glucosylates ABA in vitro and in vivo. Mutation of UGT71C5 and down-expression of UGT71C5 in Arabidopsis cause delay in seed germination and enhanced drought tolerance. In contrast, overexpression of UGT71C5 accelerates seed germination and reduces drought tolerance. Determination of the content of ABA and ABA-GE in Arabidopsis revealed that mutation in UGT71C5 and down-expression of UGT71C5 resulted in increased level of ABA and reduced level of ABA-GE, whereas overexpression of UGT71C5 resulted in reduced level of ABA and increased level of ABA-GE. Furthermore, altered levels of ABA in plants lead to changes in transcript abundance of ABA-responsive genes, correlating with the concentration of ABA regulated by UGT71C5 in Arabidopsis. Our work shows that UGT71C5 plays a major role in ABA glucosylation for ABA homeostasis.

  6. A Truncated Arabidopsis NUCLEOSOME ASSEMBLY PROTEIN 1,AtNAP1;3T,Alters Plant Growth Responses to Abscisic Acid and Salt in the Atnap 1;3-2 Mutant

    Institute of Scientific and Technical Information of China (English)

    Zi-Qiang Liu; Juan Gao; Ai-Wu Dong

    2009-01-01

    Chromatin remodeling is thought to have crucial roles in plant adaptive response to environmental stimulus.Here,we report that,in Arebidopsis,the evolutionarily conserved histone chaperone,NUCLEOSOME ASSEMBLY PROTEIN 1 (NAP1),is involved in plant response to abscisic acid (ABA),a phytohormone important in stress adaptation.We show that simultaneous loss-of-function of AtNAP1;1,AtNAP1;2,and AtNAP1;3 (the triple mutant m123-1) caused a slight hypersensitive response to ABA in seedling growth.Strikingly,the other triple mutant m123-2 containing a different mutant allele of AtNAP1;3,the Atnap1;3-2 allele,showed a hyposensitive response to ABA and a decreased tolerance to salt stress.This ABAhyposensitive and salt response phenotype specifically associated with the Atnap1;3-2 mutant allele.We show that this mutant allele produced a truncated protein,AtNAP1;3T,which lacks 34 amino acids at the C-terminus compared to the wild-type protein AtNAP1;3.We further show that the heterozygous plants containing the Atnap1;3-2 mutant allele as well as transgenic plants overexpressing AtNAP1;3T exhibit ABA-hyposensitive phenotype.It thus indicates that AtNAP1;3T functions as a dominant negative factor in ABA response.The expression of some ABA-responsive genes,including genes encoding protein kinases and transcription regulators,was found perturbed in the mutant and in the AtNAP1;3T transgenic plants.Taken together,our study uncovered AtNAP1 proteins as positive regulators and AtNAP1;3T as a negative regulator in ABA signaling pathways,providing a novel link of chromatin remodeling to hormonal and stress responses.

  7. Abscisic acid is a negative regulator of root gravitropism in Arabidopsis thaliana.

    Science.gov (United States)

    Han, Woong; Rong, Honglin; Zhang, Hanma; Wang, Myeong-Hyeon

    2009-01-23

    The plant hormone abscisic acid (ABA) plays a role in root gravitropism and has led to an intense debate over whether ABA acts similar to auxin by translating the gravitational signal into directional root growth. While tremendous advances have been made in the past two decades in establishing the role of auxin in root gravitropism, little progress has been made in characterizing the role of ABA in this response. In fact, roots of plants that have undetectable levels of ABA and that display a normal gravitropic response have raised some serious doubts about whether ABA plays any role in root gravitropism. Here, we show strong evidence that ABA plays a role opposite to that of auxin and that it is a negative regulator of the gravitropic response of Arabidopsis roots.

  8. A STRESS-RESPONSIVE NAC1-regulated protein phosphatase gene rice protein phosphatase18 modulates drought and oxidative stress tolerance through abscisic acid-independent reactive oxygen species scavenging in rice.

    Science.gov (United States)

    You, Jun; Zong, Wei; Hu, Honghong; Li, Xianghua; Xiao, Jinghua; Xiong, Lizhong

    2014-12-01

    Plants respond to abiotic stresses through a complexity of signaling pathways, and the dephosphorylation mediated by protein phosphatase (PP) is an important event in this process. We identified a rice (Oryza sativa) PP2C gene, OsPP18, as a STRESS-RESPONSIVE NAC1 (SNAC1)-regulated downstream gene. The ospp18 mutant was more sensitive than wild-type plants to drought stress at both the seedling and panicle development stages. Rice plants with OsPP18 suppressed through artificial microRNA were also hypersensitive to drought stress. Microarray analysis of the mutant revealed that genes encoding reactive oxygen species (ROS) scavenging enzymes were down-regulated in the ospp18 mutant, and the mutant exhibited reduced activities of ROS scavenging enzymes and increased sensitivity to oxidative stresses. Overexpression of OsPP18 in rice led to enhanced osmotic and oxidative stress tolerance. The expression of OsPP18 was induced by drought stress but not induced by abscisic acid (ABA). Although OsPP18 is a typical PP2C with enzymatic activity, it did not interact with SNF1-RELATED PROTEIN KINASE2 protein kinases, which function in ABA signaling. Meanwhile, the expression of ABA-responsive genes was not affected in the ospp18 mutant, and the ABA sensitivities of the ospp18 mutant and OsPP18-overexpressing plants were also not altered. Together, these findings suggest that OsPP18 is a unique PP2C gene that is regulated by SNAC1 and confers drought and oxidative stress tolerance by regulating ROS homeostasis through ABA-independent pathways.

  9. Identification of Open Stomata1-Interacting Proteins Reveals Interactions with Sucrose Non-fermenting1-Related Protein Kinases2 and with Type 2A Protein Phosphatases That Function in Abscisic Acid Responses.

    Science.gov (United States)

    Waadt, Rainer; Manalansan, Bianca; Rauniyar, Navin; Munemasa, Shintaro; Booker, Matthew A; Brandt, Benjamin; Waadt, Christian; Nusinow, Dmitri A; Kay, Steve A; Kunz, Hans-Henning; Schumacher, Karin; DeLong, Alison; Yates, John R; Schroeder, Julian I

    2015-09-01

    The plant hormone abscisic acid (ABA) controls growth and development and regulates plant water status through an established signaling pathway. In the presence of ABA, pyrabactin resistance/regulatory component of ABA receptor proteins inhibit type 2C protein phosphatases (PP2Cs). This, in turn, enables the activation of Sucrose Nonfermenting1-Related Protein Kinases2 (SnRK2). Open Stomata1 (OST1)/SnRK2.6/SRK2E is a major SnRK2-type protein kinase responsible for mediating ABA responses. Arabidopsis (Arabidopsis thaliana) expressing an epitope-tagged OST1 in the recessive ost1-3 mutant background was used for the copurification and identification of OST1-interacting proteins after osmotic stress and ABA treatments. These analyses, which were confirmed using bimolecular fluorescence complementation and coimmunoprecipitation, unexpectedly revealed homo- and heteromerization of OST1 with SnRK2.2, SnRK2.3, OST1, and SnRK2.8. Furthermore, several OST1-complexed proteins were identified as type 2A protein phosphatase (PP2A) subunits and as proteins involved in lipid and galactolipid metabolism. More detailed analyses suggested an interaction network between ABA-activated SnRK2-type protein kinases and several PP2A-type protein phosphatase regulatory subunits. pp2a double mutants exhibited a reduced sensitivity to ABA during seed germination and stomatal closure and an enhanced ABA sensitivity in root growth regulation. These analyses add PP2A-type protein phosphatases as another class of protein phosphatases to the interaction network of SnRK2-type protein kinases.

  10. Emerging roles of protein kinase CK2 in abscisic acid (ABA signaling

    Directory of Open Access Journals (Sweden)

    Belmiro eVilela

    2015-11-01

    Full Text Available The phytohormone abscisic acid (ABA regulates many aspects of plant growth and development as well as responses to multiple stresses. Post-translational modifications such as phosphorylation or ubiquitination have pivotal roles in the regulation of ABA signaling. In addition to the positive regulator sucrose non-fermenting-1 related protein kinase 2 (SnRK2, the relevance of the role of other protein kinases, such as CK2, has been recently highlighted. We have recently established that CK2 phosphorylates the maize ortholog of open stomata 1 OST1, ZmOST1, suggesting a role of CK2 phosphorylation in the control of ZmOST1 protein degradation (Vilela et al., 2015. CK2 is a pleiotropic enzyme involved in multiple developmental and stress-responsive pathways. This review summarizes recent advances that taken together suggest a prominent role of protein kinase CK2 in ABA signaling and related processes.

  11. Proline and Abscisic Acid Content in Droughted Corn Plant Inoculated with Azospirillum sp. and Arbuscular Mycorrhizae Fungi

    Directory of Open Access Journals (Sweden)

    NOVRI YOULA KANDOWANGKO

    2009-03-01

    Full Text Available Plants that undergo drought stress perform a physiological response such as accumulation of proline in the leaves and increased content abscisic acid. A research was conducted to study proline and abscisic acid (ABA content on drought-stressed corn plant with Azospirillum sp. and arbuscular mycorrhizae fungi (AMF inoculated at inceptisol soil from Bogor, West Java. The experiments were carried out in a green house from June up to September 2003, using a factorial randomized block design. In pot experiments, two factors were assigned, i.e. inoculation with Azospirillum (0, 0.50, 1.00, 1.50 ml/pot and inoculation with AMF Glomus manihotis (0, 12.50, 25.00, 37.50 g/pot. The plants were observed during tasseling up to seed filling periods. Results of experiments showed that the interaction between Azospirillum sp. and AMF was synergistically increased proline, however it decreased ABA.

  12. Accumulation of eicosapolyenoic acids enhances sensitivity to abscisic acid and mitigates the effects of drought in transgenic Arabidopsis thaliana.

    Science.gov (United States)

    Yuan, Xiaowei; Li, Yaxiao; Liu, Shiyang; Xia, Fei; Li, Xinzheng; Qi, Baoxiu

    2014-04-01

    IgASE1, a C₁₈ Δ(9)-specific polyunsaturated fatty acid elongase from the marine microalga Isochrysis galbana, is able to convert linoleic acid and α-linolenic acid to eicosadienoic acid and eicosatrienoic acid in Arabidopsis. Eicosadienoic acid and eicosatrienoic acid are precursors of arachidonic acid, eicosapentaenoic acid, and docosahexaenoic acid, which are synthesized via the Δ(8) desaturation biosynthetic pathways. This study shows that the IgASE1-expressing transgenic Arabidopsis exhibited altered morphology (decreased leaf area and biomass) and enhanced drought resistance compared to wild-type plants. The transgenic Arabidopsis were hypersensitive to abscisic acid (ABA) during seed germination, post-germination growth, and seedling development. They had elevated leaf ABA levels under well-watered and dehydrated conditions and their stomata were more sensitive to ABA. Exogenous application of eicosadienoic acid and eicosatrienoic acid can mimic ABA and drought responses in the wild type plants, similar to that found in the transgenic ones. The transcript levels of genes involved in the biosynthesis of ABA (NCED3, ABA1, AAO3) as well as other stress-related genes were upregulated in this transgenic line upon osmotic stress (300 mM mannitol). Taken together, these results indicate that these two eicosapolyenoic acids or their derived metabolites can mitigate the effects of drought in transgenic Arabidopsis, at least in part, through the action of ABA.

  13. Abscisic acid effects on activity and expression of barley (Hordeum vulgare) plastidial glucose-6-phosphate dehydrogenase.

    Science.gov (United States)

    Cardi, Manuela; Chibani, Kamel; Cafasso, Donata; Rouhier, Nicolas; Jacquot, Jean-Pierre; Esposito, Sergio

    2011-07-01

    Total glucose-6-phosphate dehydrogenase (G6PDH) activity, protein abundance, and transcript levels of G6PDH isoforms were measured in response to exogenous abscisic acid (ABA) supply to barley (Hordeum vulgare cv Nure) hydroponic culture. Total G6PDH activity increased by 50% in roots treated for 12 h with exogenous 0.1 mM ABA. In roots, a considerable increase (35%) in plastidial P2-G6PDH transcript levels was observed during the first 3 h of ABA treatment. Similar protein variations were observed in immunoblotting analyses. In leaves, a 2-fold increase in total G6PDH activity was observed after ABA treatment, probably related to an increase in the mRNA level (increased by 50%) and amount of protein (increased by 85%) of P2-G6PDH. Together these results suggest that the plastidial P2-isoform plays an important role in ABA-treated barley plants.

  14. Regulation of Senescence in Carnation (Dianthus caryophyllus): Effect of Abscisic Acid and Carbon Dioxide on Ethylene Production.

    Science.gov (United States)

    Mayak, S; Dilley, D R

    1976-11-01

    Abscisic acid hastened senescence of carnation flowers and this was preceded by stimulation of accelerated ethylene production. Carbon dioxide delayed the onset of autocatalytic ethylene production in flowers regardless of treatment with abscisic acid. Flowers exhibited a low and transient climacteric of ethylene production without wilting while in 4% carbon dioxide and underwent accelerated ethylene production culminating in wilting when removed from carbon dioxide. Hypobaric ventilation, which lowers ethylene to hyponormal levels within tissues, extended flower longevity and largely negated enhancement of senescence by abscisic acid. Supplementing hypobarically ventilated flowers with ethylene hastened senescence irrespective of abscisic acid treatment. Collectively, the data indicate that abscisic acid hastens senescence of carnations largely as a result of advancing the onset of autocatalytic ethylene production.

  15. Genetic Analysis of Ca2+ Priming in Arabidopsis Guard Cell Stomatal Closure in Response to the Drought Hormone Abscisic Acid

    Energy Technology Data Exchange (ETDEWEB)

    Stephan, Aaron B. [Life Sciences Research Foundation, Baltimore, MD (United States)

    2014-11-01

    A primary objective of modern agriculture and biofuel production is to utilize arable land to its fullest potential. However, sub-optimal growing conditions—arising from abiotic stresses such as drought, soil salinity, low humidity, cold, and heat—reduce crop yield and quality. Optimal yield under both stressed and non-stressed conditions requires the plant to activate coping mechanisms at a level commensurate with the severity of the drought stress. The osmotic sensors and associated regulatory mechanisms that initiate drought- and salt-tolerance responses in plants are largely unknown. This research aimed to identify and characterize these initial sensory components.

  16. Abscisic acid form, concentration, and application timing influence phenology and bud cold hardiness in Merlot grapevines

    Science.gov (United States)

    The effects of abscisic acid (ABA) form, concentration and application timing on bud cold hardiness, phenology and fruiting performance on ‘Merlot’ grapevines (Vitis vinifera) were evaluated in a three year field trial with site locations in British Columbia Canada, Ontario Canada, Washington U.S. ...

  17. Involvement of a lipoxygenase-like enzyme in abscisic Acid biosynthesis.

    Science.gov (United States)

    Creelman, R A; Bell, E; Mullet, J E

    1992-07-01

    Several lines of evidence indicate that abscisic acid (ABA) is derived from 9'-cis-neoxanthin or 9'-cis-violaxanthin with xanthoxin as an intermediate. (18)O-labeling experiments show incorporation primarily into the side chain carboxyl group of ABA, suggesting that oxidative cleavage occurs at the 11, 12 (11', 12') double bond of xanthophylls. Carbon monoxide, a strong inhibitor of heme-containing P-450 monooxygenases, did not inhibit ABA accumulation, suggesting that the oxygenase catalyzing the carotenoid cleavage step did not contain heme. This observation, plus the ability of lipoxygenase to make xanthoxin from violaxanthin, suggested that a lipoxygenase-like enzyme is involved in ABA biosynthesis. To test this idea, the ability of several soybean (Glycine max L.) lipoxygenase inhibitors (5,8,11-eicosatriynoic acid, 5,8,11,14-eicosatetraynoic acid, nordihydroguaiaretic acid, and naproxen) to inhibit stress-induced ABA accumulation in soybean cell culture and soybean seedlings was determined. All lipoxygenase inhibitors significantly inhibited ABA accumulation in response to stress. These results suggest that the in vivo oxidative cleavage reaction involved in ABA biosynthesis requires activity of a nonheme oxygenase having lipoxygenase-like properties.

  18. Control of Ribonuclease and Acid Phosphatase by Auxin and Abscisic Acid during Senescence of Rhoeo Leaf Sections 1

    Science.gov (United States)

    De Leo, Pietro; Sacher, Joseph A.

    1970-01-01

    We report the effects of abscisic acid and auxin (α-naphthalene acetic acid) on regulation of enzyme synthesis during senescence of leaf sections of Rhoeo discolor Hance. Abscisic acid always accelerates the onset of and enhances the magnitude of the increase in activity of acid phosphatase; this is followed by an acceleration of the onset of a rapid increase in free space. RNase activity increases 2- to 5-fold after cutting of leaf sections. Abscisic acid increases RNase activity and inhibits the rate of incorporation of uridine and leucine in leaf sections removed from plants grown under stress but not favorable conditions. Auxin inhibits the increase in RNase and acid phosphatase and suppresses the effects of abscisic acid. The increase in activity of RNase and acid phosphatase is inhibited by inhibitors of RNA and protein synthesis. This and other evidence suggests that the increases in hydrolase activity could result from new enzyme synthesis. The possible significance of the results in respect of hormonal regulation of enzyme activity and senescence is discussed. PMID:5500207

  19. Control of ribonuclease and acid phosphatase by auxin and abscisic acid during senescence of Rhoeo leaf sections.

    Science.gov (United States)

    De Leo, P; Sacher, J A

    1970-12-01

    We report the effects of abscisic acid and auxin (alpha-naphthalene acetic acid) on regulation of enzyme synthesis during senescence of leaf sections of Rhoeo discolor Hance. Abscisic acid always accelerates the onset of and enhances the magnitude of the increase in activity of acid phosphatase; this is followed by an acceleration of the onset of a rapid increase in free space.RNase activity increases 2- to 5-fold after cutting of leaf sections. Abscisic acid increases RNase activity and inhibits the rate of incorporation of uridine and leucine in leaf sections removed from plants grown under stress but not favorable conditions. Auxin inhibits the increase in RNase and acid phosphatase and suppresses the effects of abscisic acid. The increase in activity of RNase and acid phosphatase is inhibited by inhibitors of RNA and protein synthesis. This and other evidence suggests that the increases in hydrolase activity could result from new enzyme synthesis. The possible significance of the results in respect of hormonal regulation of enzyme activity and senescence is discussed.

  20. Two glucosylated abscisic acid derivates from avocado seeds (Persea americana Mill. Lauraceae cv. Hass).

    Science.gov (United States)

    del Refugio Ramos, María; Jerz, Gerold; Villanueva, Socorro; López-Dellamary, Fernando; Waibel, Reiner; Winterhalter, Peter

    2004-04-01

    Phytochemical investigation of avocado seed material (Persea americana Mill., Lauraceae) resulted in the isolation of two glucosylated abscisic acid derivates. One of these was not known as a natural product and can be regarded as a potential 'missing link' in abscisic acid metabolism in plants. After fractionation by high-speed countercurrent chromatography, and multiple steps of column chromatography, structures were elucidated by 1D-, 2D-NMR, electrospray-MS to be the novel beta-d-glucoside of (1'S,6'R)-8'-hydroxyabscisic acid, and (1'R,3'R,5'R,8'S)-epi-dihydrophaseic acid beta-d-glucoside. Absolute configuration was determined by circulardichroism, optical rotation, and by NOE experiments.

  1. Biotechnological characteristics of callusogenesis in maize immature embryo culture under the influence of abscisic acid and 6-benzylaminopurine

    Directory of Open Access Journals (Sweden)

    O. E. Abraimova

    2010-02-01

    Full Text Available The effect of abscisic acid and 6-benzylaminopurine on the induction of callus tissue in maize immature embryo culture was studied. For the majority of investigated genotypes abscisic acid stimulated, but 6-benzylaminopurine inhibited the formation of morphogenic calli in induction medium. It was noted that genotype appeared to be an important factor that determined the character of the influence of phytohormonal composition of the medium on the induction of the specific types of calli. Using of 0.04-0.10 mg/l abscisic acid is recommended for biotechnological production of morphogenic callus tissue in dependence of donor plant genotype.

  2. Functional analysis of a Lemna gibba rbcS promoter regulated by abscisic acid and sugar

    Indian Academy of Sciences (India)

    Youru Wang

    2013-04-01

    Photosynthesis-associated nuclear genes (PhANGs) are able to respond to multiple environmental and developmental signals, including light, sugar and abscisic acid (ABA). PhANGs have been extensively studied at the level of transcriptional regulation, and several cis-acting elements important for light responsiveness have been identified in their promoter sequences. However, the regulatory elements involved in sugar and ABA regulation of PhANGs have not been completely characterized. A ribulose-1,5-bisphosphate carboxylase small subunit gene (rbcS) promoter (SSU5C promoter) was isolated from duckweed (Lemna gibba). A series of SSU5C promoter 5′ deletion fragments were fused to an intron–gus gene, and transgenic tobacco suspension cell lines were generated. Assay of tobacco suspension cell line harbouring the complete promoter in the fusion construct indicated that SSU5C promoter was negatively regulated by sugar and ABA under the condition of regular photoperiod. 5′ deletion analysis of SSU5C promoter in transgenic tobacco suspension cell lines confirmed that a region between positions $-310$ and $-152$ included the ABA-response region, and that sugar-response cis-acting elements might be located in the region between $-152$ and $-117$. Taken together, our results confirmed that the cis-regulatory region responsible for repression by ABA and sugar in the SSU5C promoter was located between $-310$ and $-117$.

  3. Phenolic compounds in juice of “Isabel” grape treated with abscisic acid for color improvement

    Directory of Open Access Journals (Sweden)

    Yamamoto Lilian Yukari

    2015-01-01

    Full Text Available Isabel grape is the main cultivar used to produce juice in Brazil, which has rusticity and high productivity, but it is deficient in anthocyanins, a pigment responsible for the color. Thus, an alternative is the application of abscisic acid (S-ABA, which is responsible to promote the synthesis of anthocyanins. The aim of this work was to evaluate the phenolic compounds composition in “Isabel” grape juice treated with S-ABA, by HPLC-DAD–ESI-MS/MS technique. The results showed the increasing in total anthocyanin concentration in juices, with S-ABA treatments, as well as the proportion of B-ring tri-substituted anthocyanidins. Regarding total flavonols, differences were only significant in juices obtained in 2012 season. S-ABA treatments did not significantly affect the hydroxycinnamic acid derivatives, flavan-3-ols, resveratrol and antioxidant capacity of juices. Juice from “Isabel” grapes treated with S-ABA provides an enhancement of total anthocyanin concentration, mainly when grapes are treated before or at the onset of véraison.

  4. Hydrogen peroxide modulates abscisic acid signaling in root growth and development in Arabidopsis

    Institute of Scientific and Technical Information of China (English)

    BAI Ling; ZHOU Yun; ZHANG XiaoRan; SONG ChunPeng; Gao MingQing

    2007-01-01

    Exogenous abscisic acid (ABA) can inhibit root growth and promote formation of more root hairs in the root tip of Arabidopsis. However, the molecular mechanisms that underlie root ABA signaling are largely unknown. We report here that hydrogen peroxide (H2O2) reduces the root growth of wild type,and the phenotype of H2O2 on the root growth is similar to ABA response. Meanwhile ABA-induced changes in the morphology of root system can be partly reversed by ascorbic acid in wild type and abolished in NADPH oxidase defective mutant atrbohF and atrbohC. Further, ABA can induce H2O2 accumulation in the root cells and enhance transcription level of OXI1, which is necessary for many more AOS-dependent processes such as root hair growth in Arabidopsis. Our results suggest that H2O2 as an important signal molecule is required for the ABA-regulated root growth and development in Arabidopsis.

  5. Potassium channel currents in intact stomatal guard cells: rapid enhancement by abscisic acid.

    Science.gov (United States)

    Blatt, M R

    1990-02-01

    Evidence of a role for abscisic acid (ABA) in signalling conditions of water stress and promoting stomatal closure is convincing, but past studies have left few clues as to its molecular mechanism(s) of action; arguments centred on changes in H(+)-pump activity and membrane potential, especially, remain ambiguous without the fundamental support of a rigorous electrophysiological analysis. The present study explores the response to ABA of K(+) channels at the membrane of intact guard cells of Vicia faba L. Membrane potentials were recorded before and during exposures to ABA, and whole-cell currents were measured at intervals throughout to quantitate the steady-state and time-dependent characteristics of the K(+) channels. On adding 10 μM ABA in the presence of 0.1, 3 or 10 mM extracellular K(+), the free-running membrane potential (V m) shifted negative-going (-)4-7 mV in the first 5 min of exposure, with no consistent effect thereafter. Voltage-clamp measurements, however, revealed that the K(+)-channel current rose to between 1.84- and 3.41-fold of the controls in the steady-state with a mean halftime of 1.1 ± 0.1 min. Comparable changes in current return via the leak were also evident and accounted for the minimal response in V m. Calculated at V m, the K(+) currents translated to an average 2.65-fold rise in K(+) efflux with ABA. Abscisic acid was not observed to alter either K(+)-current activation or deactivation.These results are consistent with an ABA-evoked mobilization of K(+) channels or channel conductance, rather than a direct effect of the phytohormone on K(+)-channel gating. The data discount notions that large swings in membrane voltage are a prerequisite to controlling guard-cell K(+) flux. Instead, thev highlight a rise in membrane capacity for K(+) flux, dependent on concerted modulations of K(+)-channel and leak currents, and sufficiently rapid to account generally for the onset of K(+) loss from guard cells and stomatal closure in ABA.

  6. Effects of lanthanum on abscisic acid regulation of root growth in Arabidopsis

    Institute of Scientific and Technical Information of China (English)

    王建荣; 王蕾; 胡婷; 李文超; 薛绍武

    2014-01-01

    Rare earth elements (REEs) were reported to have adverse biology effects on plant growth and production. However, whether REEs are involved in plant hormone abscisic acid signal is not clear. Here we reported that REE lanthanum (La) interacted with abscisic acid (ABA) in the regulation of seed germination and root growth in model plant Arabidopsis. La3+at a concentration of 10 µmol/L alleviated ABA depression of seed germination and reversed ABA inhibition of root elongation growth in Arabidopsis. Previous studies showed that ABA could promote root hair development. In the present study, La3+inhibited root hair development promoted by ABA. Moreover, La3+inhibited H2O2 generation induced by ABA in root cells. Therefore we inferred that La3+might interact with ABA upstream of H2O2 generation.

  7. A gate-latch-lock mechanism for hormone signalling by abscisic acid receptors

    KAUST Repository

    Melcher, Karsten

    2009-12-03

    Abscisic acid (ABA) is a ubiquitous hormone that regulates plant growth, development and responses to environmental stresses. Its action is mediated by the PYR/PYL/RCAR family of START proteins, but it remains unclear how these receptors bind ABA and, in turn, how hormone binding leads to inhibition of the downstream type 2C protein phosphatase (PP2C) effectors. Here we report crystal structures of apo and ABA-bound receptors as well as a ternary PYL2-ABA-PP2C complex. The apo receptors contain an open ligand-binding pocket flanked by a gate that closes in response to ABA by way of conformational changes in two highly conserved ?-loops that serve as a gate and latch. Moreover, ABA-induced closure of the gate creates a surface that enables the receptor to dock into and competitively inhibit the PP2C active site. A conserved tryptophan in the PP2C inserts directly between the gate and latch, which functions to further lock the receptor in a closed conformation. Together, our results identify a conserved gate-latch-lock mechanism underlying ABA signalling. © 2009 Macmillan Publishers Limited. All rights reserved.

  8. Fern and lycophyte guard cells do not respond to endogenous abscisic acid.

    Science.gov (United States)

    McAdam, Scott A M; Brodribb, Timothy J

    2012-04-01

    Stomatal guard cells regulate plant photosynthesis and transpiration. Central to the control of seed plant stomatal movement is the phytohormone abscisic acid (ABA); however, differences in the sensitivity of guard cells to this ubiquitous chemical have been reported across land plant lineages. Using a phylogenetic approach to investigate guard cell control, we examined the diversity of stomatal responses to endogenous ABA and leaf water potential during water stress. We show that although all species respond similarly to leaf water deficit in terms of enhanced levels of ABA and closed stomata, the function of fern and lycophyte stomata diverged strongly from seed plant species upon rehydration. When instantaneously rehydrated from a water-stressed state, fern and lycophyte stomata rapidly reopened to predrought levels despite the high levels of endogenous ABA in the leaf. In seed plants under the same conditions, high levels of ABA in the leaf prevented rapid reopening of stomata. We conclude that endogenous ABA synthesized by ferns and lycophytes plays little role in the regulation of transpiration, with stomata passively responsive to leaf water potential. These results support a gradualistic model of stomatal control evolution, offering opportunities for molecular and guard cell biochemical studies to gain further insights into stomatal control.

  9. The dynamics of embolism refilling in abscisic acid (ABA)-deficient tomato plants.

    Science.gov (United States)

    Secchi, Francesca; Perrone, Irene; Chitarra, Walter; Zwieniecka, Anna K; Lovisolo, Claudio; Zwieniecki, Maciej A

    2012-12-24

    Plants are in danger of embolism formation in xylem vessels when the balance between water transport capacity and transpirational demand is compromised. To maintain this delicate balance, plants must regulate the rate of transpiration and, if necessary, restore water transport in embolized vessels. Abscisic acid (ABA) is the dominant long-distance signal responsible for plant response to stress, and it is possible that it plays a role in the embolism/refilling cycle. To test this idea, a temporal analysis of embolism and refilling dynamics, transpiration rate and starch content was performed on ABA-deficient mutant tomato plants. ABA-deficient mutants were more vulnerable to embolism formation than wild-type plants, and application of exogenous ABA had no effect on vulnerability. However, mutant plants treated with exogenous ABA had lower stomatal conductance and reduced starch content in the xylem parenchyma cells. The lower starch content could have an indirect effect on the plant's refilling activity. The results confirm that plants with high starch content (moderately stressed mutant plants) were more likely to recover from loss of water transport capacity than plants with low starch content (mutant plants with application of exogenous ABA) or plants experiencing severe water stress. This study demonstrates that ABA most likely does not play any direct role in embolism refilling, but through the modulation of carbohydrate content, it could influence the plant's capacity for refilling.

  10. Interactions between ethylene, abscisic acid and cytokinin during germination and seedling establishment in Arabidopsis

    Indian Academy of Sciences (India)

    Veeraputhiran Subbiah; Karingu Janardhan Reddy

    2010-09-01

    In order to investigate the interaction of the plant hormones ethylene, abscisic acid (ABA) and cytokinin in seed germination and early seedling development, we studied germination in ethylene-related mutants of Arabidopsis. Mutations in the genes etr1 and ein2, which reduce ethylene responses, showed increased dormancy and a delay in germination in comparison with wild type. Mutations in etr1, ein2 and ein6 also resulted in increased sensitivity to ABA with respect to inhibition of germination. Conversely, mutations in ctr1 and eto3, which lead to an increased ethylene response and overproduction of ethylene, respectively, decreased sensitivity to ABA during germination. Increased ABA sensitivity was also effected in wild type seeds by the presence during germination of AgNO3, an inhibitor of ethylene action. The addition of the cytokinin N-6 benzyl adenine (BA) reversed the increased sensitivity of ethylene-resistant mutants to ABA. The action of cytokinin in reversing increased ABA sensitivity of ethylene-resistant mutants also suggests that at least part of the action of cytokinin in promoting germination is independent of its role in stimulating ethylene production. These observations further extend the evidence in support of interaction between ethylene, ABA and cytokinin signalling in controlling seed germination and early seedling development in Arabidopsis.

  11. Gibberellins and abscisic acid signal crosstalk: living and developing under unfavorable conditions.

    Science.gov (United States)

    Golldack, Dortje; Li, Chao; Mohan, Harikrishnan; Probst, Nina

    2013-07-01

    Plants adapt to adverse environments by integrating growth and development to environmentally activated cues. Within the adaptive signaling networks, plant hormones tightly control convergent developmental and stress adaptive processes and coordinate cellular responses to external and internal conditions. Recent studies have uncovered novel antagonizing roles of the plant hormones gibberellin (GA) and abscisic acid (ABA) in integrating growth and development in plants with environmental signaling. According to current concepts, GRAS transcription factors of the DELLA and SCARECROW-LIKE (SCL) types have a key role as major growth regulators and have pivotal functions in modulating GA signaling. Significantly, current models emphasize a function of DELLA proteins as central regulators in GA homeostasis. DELLA proteins interact with the cellular GA receptor GID1 (GA-INSENSITIVE DWARF1) and degradation of DELLAs activates the function of GA. Supplementary to the prevailing view of a pivotal role of GRAS family transcriptional factors in plant growth regulation, recent work has suggested that the DELLA and SCL proteins integrate generic GA responses into ABA-controlled abiotic stress tolerance. Here, we review and discuss how GRAS type proteins influence plant development and versatile adaptation as hubs in GA and ABA triggered signaling pathways.

  12. The Dynamics of Embolism Refilling in Abscisic Acid (ABA-Deficient Tomato Plants

    Directory of Open Access Journals (Sweden)

    Francesca Secchi

    2012-12-01

    Full Text Available Plants are in danger of embolism formation in xylem vessels when the balance between water transport capacity and transpirational demand is compromised. To maintain this delicate balance, plants must regulate the rate of transpiration and, if necessary, restore water transport in embolized vessels. Abscisic acid (ABA is the dominant long-distance signal responsible for plant response to stress, and it is possible that it plays a role in the embolism/refilling cycle. To test this idea, a temporal analysis of embolism and refilling dynamics, transpiration rate and starch content was performed on ABA-deficient mutant tomato plants. ABA-deficient mutants were more vulnerable to embolism formation than wild-type plants, and application of exogenous ABA had no effect on vulnerability. However, mutant plants treated with exogenous ABA had lower stomatal conductance and reduced starch content in the xylem parenchyma cells. The lower starch content could have an indirect effect on the plant’s refilling activity. The results confirm that plants with high starch content (moderately stressed mutant plants were more likely to recover from loss of water transport capacity than plants with low starch content (mutant plants with application of exogenous ABA or plants experiencing severe water stress. This study demonstrates that ABA most likely does not play any direct role in embolism refilling, but through the modulation of carbohydrate content, it could influence the plant’s capacity for refilling.

  13. Abscisic acid induces biosynthesis of bisbibenzyls and tolerance to UV-C in the liverwort Marchantia polymorpha.

    Science.gov (United States)

    Kageyama, Akito; Ishizaki, Kimitsune; Kohchi, Takayuki; Matsuura, Hideyuki; Takahashi, Kosaku

    2015-09-01

    Environmental stresses are effective triggers for the biosynthesis of various secondary metabolites in plants, and phytohormones such as jasmonic acid and abscisic acid are known to mediate such responses in flowering plants. However, the detailed mechanism underlying the regulation of secondary metabolism in bryophytes remains unclear. In this study, the induction mechanism of secondary metabolites in the model liverwort Marchantia polymorpha was investigated. Abscisic acid (ABA) and ultraviolet irradiation (UV-C) were found to induce the biosynthesis of isoriccardin C, marchantin C, and riccardin F, which are categorized as bisbibenzyls, characteristic metabolites of liverworts. UV-C led to the significant accumulation of ABA. Overexpression of MpABI1, which encodes protein phosphatase 2C (PP2C) as a negative regulator of ABA signaling, suppressed accumulation of bisbibenzyls in response to ABA and UV-C irradiation and conferred susceptibility to UV-C irradiation. These data show that ABA plays a significant role in the induction of bisbibenzyl biosynthesis, which might confer tolerance against UV-C irradiation in M. polymorpha.

  14. Abscisic Acid and Cytokinin-Induced Osmotic and Antioxidant Regulation in Two Drought-Tolerant and Drought-Sensitive Cultivars of Wheat During Grain Filling Under Water Deficit in Field Conditions

    Directory of Open Access Journals (Sweden)

    Mohammad-Reza SARAFRAZ-ARDAKANI

    2014-09-01

    Full Text Available Phytohormones play critical roles in regulating plant responses to stress. The present study investigates the effect of cytokinin, abscisic acid and cytokinin/abscisic acid interaction on some osmoprotectants and antioxidant parameters induced by drought stress in two wheat cultivars (Triticum aestivum L. of ‘Pishgam’ and ‘MV-17’ as tolerant and sensitive to drought during post-anthesis phase, respectively grown in field conditions. The most considerable effect of the treatments was exhibited 21 days after anthesis. Under drought conditions, the flag leaf soluble carbohydrate content increased in both cultivars while starch content was remarkably decreased in ‘Pishgam’ as compared to ‘MV-17’. Abscisic acid increased total soluble sugar and reduced starch more than other hormonal treatments, although it decreased studied monosaccharaides in ‘Pishgam’, especially. Drought stress induced high proportion of gylycinebetain and free proline in ‘Pishgam’ cultivar. Application of abscisic acid and cytokinin/abscisic acid interaction increased gylycinebetain and proline content in both cultivars under irrigation and drought conditions. The tolerant cultivar exhibited less accumulation of hydrogen peroxide and malondialdehyde in relation to significant increase of catalase and peroxidase activities and α-tocpherol content under drought conditions. All hormonal treatments increased the named enzyme activities under both irrigation and drought conditions, while higher accumulation of α-tocopherol was only showed in case of cytokinin application. Also, abscisic acid and cytokinin/abscisic acid could decrease drought-induced hydrogen peroxide and malondialdehyde level to some extent, although abscisic acid increased both of hydrogen peroxide andmalondialdehyde content in irrigation phase, especially.

  15. Abscisic acid is not necessary for gravitropism in primary roots of Zea mays

    Science.gov (United States)

    Moore, R.

    1990-01-01

    Primary roots of Zea mays L. cv. Tx 5855 treated with fluridone are strongly graviresponsive, but have undetectable levels of abscisic acid (ABA). Primary roots of the carotenoid-deficient w-3, vp-5, and vp-7 mutants of Z. mays are also graviresponsive despite having undetectable amounts of ABA. Graviresponsive roots of untreated and wild-type seedlings contain 286 to 317 ng ABA g-1 f. wt, respectively. These results indicate that ABA is not necessary for root gravicurvature.

  16. EFFECT OF EXOGENOUS ABSCISIC ACID ON GROWTH AND BIOCHEMICAL CHANGES IN THE HALOPHYTE SUAEDA MARITIMA

    Directory of Open Access Journals (Sweden)

    Anbarasi G.

    2015-04-01

    Full Text Available Different types of phytohormones are being extensively used to alleviate the adverse effect of salinity stress on plant growth. Among those, Abscisic acid (ABA is a plant stress hormone and one of the most important signaling molecules in plants. Drought and salinity activate De-novo abscisic acid synthesis prevent further water loss by evaporation through stomata, mediated by changes in the guard cell turgor pressure. Under osmotic stress abscisic acid induce the accumulation of protein involved in the biosynthesis of osmolites which increasing the stress tolerance of plant. In addition, exogenous application of ABA enhances the tolerance of plants or plant cells to cold, heat, drought, anoxia and heavy metal stresses. This study was carried out to study the exogenous abscisic (ABA acid induced regulatory role on the growth, water content, protein content, chlorophyll content, osmolyte accumulation and protein profiling through SDS PAGE in a halophyte, Suaeda maritima. The osmolyte accumulation of proline and glycine betaine was found to be more in 50 µM ABA concentrations. The protein profiling through SDS PAGE revealed that ̴ 66KDa proteins was not expressed in the control plant and in 10μM ABA treated plants. Interestingly, the ABA treatment induced a new protein of 14.2KDa in 10μM concentration. The ABA treated plants with concentrations 50μM, 100μM and 150μM showed changes in the expression of protein in abundance than the control and 10μM ABA treated plants. The findings in this study indicate that among all the concentrations, 50μM ABA concentration treated plants exhibited higher growth rate.

  17. Measurement of abscisic acid and gibberellins by gas chromatography/mass spectrometry.

    Science.gov (United States)

    Okamoto, Masanori; Hanada, Atsushi; Kamiya, Yuji; Yamaguchi, Shinjiro; Nambara, Eiji

    2009-01-01

    Gas chromatography-mass spectrometry (GC-MS)-based analysis is an accurate and sensitive method to quantify plant hormones. This method is commonly used for analysis of low-molecular-weight compounds, such as abscisic acid (ABA), gibberellins (GAs), auxins, and brassinosteroids. Procedures are composed of four major steps: extraction, fractionation, derivatization, and detection. Here, we describe a protocol for quantification of ABA and GAs.

  18. Inhibitors from carob (Ceratonia siliqua L.) : III. Comparisons with abscisic acid.

    Science.gov (United States)

    Corcoran, M R

    1970-06-01

    Inhibitory extracts of carob and abscisic acid (ABA) were compared and found to behave differently in three types of tests. The carob inhibitors remained at the origin upon thin-layer chromatography in two different solvent systems while a cis-trans mixture of ABA had Rf's of 2.5 and 3.5 in the first system (chloroform:acetic acid, 95:5), and 3.5 and 4.5 in the second system (benzene:acetic acid:water, 8:3:5). When ABA and carob extract were mixed and then chromatographed, the ABA had the same Rf values as ABA chromatographed alone.Assays utilizing light-grown, dwarf peas showed that a weight ratio of 1000: 1 ABA:gibberellic acid (GA3) was necessary to inhibit GA3-induced growth by 50% while carob fraction C is inhibitory to GA3 at a ratio of 17:1. The amount of ABA which inhibited 50% of the growth induced by 0.05 μg GA3 reduced the endogenous growth of both dwarf and non-dwarf pea seedlings; in contrast, concentrations of carob extract up to 100 times greater than the amount necessary for 50% inhibition of the growth response caused by 0.05 μg GA3 did not affect endogenous growth.Only very small amounts of inhibitory activity from carob extract were transferred from water to chloroform at a pH (2.0) at which most of the ABA was transferred.

  19. Induction of phytic acid synthesis by abscisic acid in suspension-cultured cells of rice.

    Science.gov (United States)

    Matsuno, Koya; Fujimura, Tatsuhito

    2014-03-01

    A pathway of phytic acid (PA) synthesis in plants has been revealed via investigations of low phytic acid mutants. However, the regulation of this pathway is not well understood because it is difficult to control the environments of cells in the seeds, where PA is mainly synthesized. We modified a rice suspension culture system in order to study the regulation of PA synthesis. Rice cells cultured with abscisic acid (ABA) accumulate PA at higher levels than cells cultured without ABA, and PA accumulation levels increase with ABA concentration. On the other hand, higher concentrations of sucrose or inorganic phosphorus do not affect PA accumulation. Mutations in the genes RINO1, OsMIK, OsIPK1 and OsLPA1 have each been reported to confer low phytic acid phenotypes in seeds. Each of these genes is upregulated in cells cultured with ABA. OsITPK4 and OsITPK6 are upregulated in cells cultured with ABA and in developing seeds. These results suggest that the regulation of PA synthesis is similar between developing seeds and cells in this suspension culture system. This system will be a powerful tool for elucidating the regulation of PA synthesis.

  20. The Arabidopsis Vacuolar Sorting Receptor1 Is Required for Osmotic Stress-Induced Abscisic Acid Biosynthesis

    KAUST Repository

    Wang, Zhen-Yu

    2014-11-21

    Osmotic stress activates the biosynthesis of the phytohormone abscisic acid (ABA) through a pathway that is rate limited by the carotenoid cleavage enzyme 9-cis-epoxycarotenoid dioxygenase (NCED). To understand the signal transduction mechanism underlying the activation of ABA biosynthesis, we performed a forward genetic screen to isolate mutants defective in osmotic stress regulation of the NCED3 gene. Here, we identified the Arabidopsis (Arabidopsis thaliana) Vacuolar Sorting Receptor1 (VSR1) as a unique regulator of ABA biosynthesis. The vsr1 mutant not only shows increased sensitivity to osmotic stress, but also is defective in the feedback regulation of ABA biosynthesis by ABA. Further analysis revealed that vacuolar trafficking mediated by VSR1 is required for osmotic stress-responsive ABA biosynthesis and osmotic stress tolerance. Moreover, under osmotic stress conditions, the membrane potential, calcium flux, and vacuolar pH changes in the vsr1 mutant differ from those in the wild type. Given that manipulation of the intracellular pH is sufficient to modulate the expression of ABA biosynthesis genes, including NCED3, and ABA accumulation, we propose that intracellular pH changes caused by osmotic stress may play a signaling role in regulating ABA biosynthesis and that this regulation is dependent on functional VSR1.

  1. Production of Polyamines Is Enhanced by Endogenous Abscisic Acid in Maize Seedlings Subjected to Salt Stress

    Institute of Scientific and Technical Information of China (English)

    Jun LIU; Ming-Yi JIANG; Yi-Feng ZHOU; You-Liang LIU

    2005-01-01

    It is known that salt stress and exogenously applied abscisic acid (ABA) can enhance the polyamine content in plants and that salt stress itself can lead to an increase in endogenous ABA production.In the present study, the relationships between salt-induced ABA and polyamine accumulation were investigated using ABA-deficient mutant (vp5/vp5) maize (Zea mays L.) seedlings and ABA and polyamine :biosynthesis inhibitors. The results show that reduced endogenous ABA levels, as a result of either the mutation or by using a chemical inhibitor (sodium tungstate), also reduced the accumulation of polyamines in salt-stressed leaves of maize seedlings. The polyamine synthesis inhibitors D-arginine and αdifluoromethylornithine also reduced the polyamine content of the leaves of maize seedling under salt stress. Both ABA and polyamine enhanced the dry weight accumulation of salt-stressed seedlings and also increased the activities of the two dominant tonoplast membrane enzymes, H+-ATPase and H+-PPase, when plants were under salt stress. The results suggest that salt stress induces an increase in endogenous ABA levels, which then enhances polyamine synthesis. Such responses may increase a plant's tolerance to salt.

  2. Autocrine abscisic acid plays a key role in quartz-induced macrophage activation.

    Science.gov (United States)

    Magnone, Mirko; Sturla, Laura; Jacchetti, Emanuela; Scarfì, Sonia; Bruzzone, Santina; Usai, Cesare; Guida, Lucrezia; Salis, Annalisa; Damonte, Gianluca; De Flora, Antonio; Zocchi, Elena

    2012-03-01

    Inhalation of quartz induces silicosis, a lung disease where alveolar macrophages release inflammatory mediators, including prostaglandin-E(2) (PGE(2)) and tumor necrosis factor α (TNF-α). Here we report the pivotal role of abscisic acid (ABA), a recently discovered human inflammatory hormone, in silica-induced activation of murine RAW264.7 macrophages and of rat alveolar macrophages (AMs). Stimulation of both RAW264.7 cells and AMs with quartz induced a significant increase of ABA release (5- and 10-fold, respectively), compared to untreated cells. In RAW264.7 cells, autocrine ABA released after quartz stimulation sequentially activates the plasma membrane receptor LANCL2 and NADPH oxidase, generating a Ca(2+) influx resulting in NFκ B nuclear translocation and PGE(2) and TNF-α release (3-, 2-, and 3.5-fold increase, respectively, compared to control, unstimulated cells). Quartz-stimulated RAW264.7 cells silenced for LANCL2 or preincubated with a monoclonal antibody against ABA show an almost complete inhibition of NFκ B nuclear translocation and PGE(2) and TNF-α release compared to controls electroporated with a scramble oligonucleotide or preincubated with an unrelated antibody. AMs showed similar early and late ABA-induced responses as RAW264.7 cells. These findings identify ABA and LANCL2 as key mediators in quartz-induced inflammation, providing possible new targets for antisilicotic therapy.

  3. Beyond gibberellins and abscisic acid: how ethylene and jasmonates control seed germination.

    Science.gov (United States)

    Linkies, Ada; Leubner-Metzger, Gerhard

    2012-02-01

    Appropriate responses of seeds and fruits to environmental factors are key traits that control the establishment of a species in a particular ecosystem. Adaptation of germination to abiotic stresses and changing environmental conditions is decisive for fitness and survival of a species. Two opposing forces provide the basic physiological mechanism for the control of seed germination: the increasing growth potential of the embryo and the restraint weakening of the various covering layers (seed envelopes), including the endosperm which is present to a various extent in the mature seeds of most angiosperms. Gibberellins (GA), abscisic acid (ABA) and ethylene signaling and metabolism mediate environmental cues and in turn influence developmental processes like seed germination. Cross-species work has demonstrated that GA, ABA and ethylene interact during the regulation of endosperm weakening, which is at least partly based on evolutionarily conserved mechanisms. We summarize the recent progress made in unraveling how ethylene promotes germination and acts as an antagonist of ABA. Far less is known about jasmonates in seeds for which we summarize the current knowledge about their role in seeds. While it seems very clear that jasmonates inhibit germination, the results obtained so far are partly contradictory and depend on future research to reach final conclusions on the mode of jasmonate action during seed germination. Understanding the mechanisms underlying the control of seed germination and its hormonal regulation is not only of academic interest, but is also the ultimate basis for further improving crop establishment and yield, and is therefore of common importance.

  4. Influence of abscisic acid on growth, biomass and lipid yield of Scenedesmus quadricauda under nitrogen starved condition.

    Science.gov (United States)

    Sulochana, Sujitha Balakrishnan; Arumugam, Muthu

    2016-08-01

    Scenedesmus quadricauda, accumulated more lipid but with a drastic reduction in biomass yield during nitrogen starvation. Abscisic acid (ABA) being a stress responsible hormone, its effect on growth and biomass with sustainable lipid yield during nitrogen depletion was studied. The result revealed that the ABA level shoots up at 24h (27.21pmol/L) during the onset of nitrogen starvation followed by a sharp decline. The external supplemented ABA showed a positive effect on growth pattern (38×10(6)cells/ml) at a lower concentration. The dry biomass yield is also increasing up to 2.1 fold compared to nitrogen deficient S. quadricauda. The lipid content sustains in 1 and 2μM concentration of ABA under nitrogen-deficient condition. The fatty acid composition of ABA treated S. quadricauda cultures with respect to nitrogen-starved cells showed 11.17% increment in saturated fatty acid content, the desired lipid composition for biofuel application.

  5. Abscisic acid in salt stress predisposition to phytophthora root and crown rot in tomato and chrysanthemum.

    Science.gov (United States)

    Dileo, Matthew V; Pye, Matthew F; Roubtsova, Tatiana V; Duniway, John M; Macdonald, James D; Rizzo, David M; Bostock, Richard M

    2010-09-01

    Plants respond to changes in the environment with complex signaling networks, often under control of phytohormones that generate positive and negative crosstalk among downstream effectors of the response. Accordingly, brief dehydration stresses such as salinity and water deficit, which induce a rapid and transient systemic increase in levels of abscisic acid (ABA), can influence disease response pathways. ABA has been associated with susceptibility of plants to bacteria, fungi, and oomycetes but relatively little attention has been directed at its role in abiotic stress predisposition to root pathogens. This study examines the impact of brief salinity stress on infection of tomato and chrysanthemum roots by Phytophthora spp. Roots of plants in hydroponic culture exposed to a brief episode of salt (sodium chloride) stress prior to or after inoculation were severely diseased relative to nonstressed plants. Tomato roots remained in a predisposed state up to 24 h following removal from the stress. An increase in root ABA levels in tomato preceded or temporally paralleled the onset of stress-induced susceptibility, with levels declining in roots prior to recovery from the predisposed state. Exogenous ABA could substitute for salt stress and significantly enhanced pathogen colonization and disease development. ABA-deficient tomato mutants lacked the predisposition response, which could be restored by complementation of the mutant with exogenous ABA. In contrast, ethylene, which exacerbates disease symptoms in some host-parasite interactions, did not appear to contribute to the predisposition response. Thus, several lines of evidence support ABA as a critical and dominant factor in the salinity-induced predisposition to Phytophthora spp. infection.

  6. Enhancing tolerance of rice (Oryza sativa) to simulated acid rain by exogenous abscisic acid.

    Science.gov (United States)

    Wu, Xi; Liang, Chanjuan

    2016-12-16

    Abscisic acid (ABA) regulates much important plant physiological and biochemical processes and induces tolerance to different stresses. Here, we studied the regulation of exogenous ABA on adaptation of rice seedlings to simulated acid rain (SAR) stress by measuring biomass dry weight, stomatal conductance, net photosynthesis rate, nutrient elements, and endogenous hormones. The application of 10 μM ABA alleviated the SAR-induced inhibition on growth, stomatal conductance, net photosynthesis rate, and decreases in contents of nutrient (K, Mg, N, and P) and hormone (auxin, gibberellins, and zeatin). Moreover, 10 μM ABA could stimulate the Ca content as signaling molecules under SAR stress. Contrarily, the application of 100 μM ABA aggravated the SAR-induced inhibition on growth, stomatal conductance, net photosynthesis rate, and contents of nutrient and hormone. The results got after a 5-day recovery (without SAR) show that exogenous 10 μM ABA can promote self-restoration process in rice whereas 100 μM ABA hindered the restoration by increasing deficiency of nutrients and disturbing the balance of hormones. These results confirmed that exogenous ABA at proper concentration could enhance the tolerance of rice to SAR stress.

  7. Salicylic acid antagonizes abscisic acid inhibition of shoot growth and cell cycle progression in rice

    Science.gov (United States)

    Meguro, Ayano; Sato, Yutaka

    2014-04-01

    We analysed effects of abscisic acid (ABA, a negative regulatory hormone), alone and in combination with positive or neutral hormones, including salicylic acid (SA), on rice growth and expression of cell cycle-related genes. ABA significantly inhibited shoot growth and induced expression of OsKRP4, OsKRP5, and OsKRP6. A yeast two-hybrid assay showed that OsKRP4, OsKRP5, and OsKRP6 interacted with OsCDKA;1 and/or OsCDKA;2. When SA was simultaneously supplied with ABA, the antagonistic effect of SA completely blocked ABA inhibition. SA also blocked ABA inhibition of DNA replication and thymidine incorporation in the shoot apical meristem. These results suggest that ABA arrests cell cycle progression by inducing expression of OsKRP4, OsKRP5, and OsKRP6, which inhibit the G1/S transition, and that SA antagonizes ABA by blocking expression of OsKRP genes.

  8. Metabolic pathways regulated by abscisic acid, salicylic acid and γ-aminobutyric acid in association with improved drought tolerance in creeping bentgrass (Agrostis stolonifera).

    Science.gov (United States)

    Li, Zhou; Yu, Jingjin; Peng, Yan; Huang, Bingru

    2017-01-01

    Abscisic acid (ABA), salicylic acid (SA) and γ-aminobutyric acid (GABA) are known to play roles in regulating plant stress responses. This study was conducted to determine metabolites and associated pathways regulated by ABA, SA and GABA that could contribute to drought tolerance in creeping bentgrass (Agrostis stolonifera). Plants were foliar sprayed with ABA (5 μM), GABA (0.5 mM) and SA (10 μM) or water (untreated control) prior to 25 days drought stress in controlled growth chambers. Application of ABA, GABA or SA had similar positive effects on alleviating drought damages, as manifested by the maintenance of lower electrolyte leakage and greater relative water content in leaves of treated plants relative to the untreated control. Metabolic profiling showed that ABA, GABA and SA induced differential metabolic changes under drought stress. ABA mainly promoted the accumulation of organic acids associated with tricarboxylic acid cycle (aconitic acid, succinic acid, lactic acid and malic acid). SA strongly stimulated the accumulation of amino acids (proline, serine, threonine and alanine) and carbohydrates (glucose, mannose, fructose and cellobiose). GABA enhanced the accumulation of amino acids (GABA, glycine, valine, proline, 5-oxoproline, serine, threonine, aspartic acid and glutamic acid) and organic acids (malic acid, lactic acid, gluconic acid, malonic acid and ribonic acid). The enhanced drought tolerance could be mainly due to the enhanced respiration metabolism by ABA, amino acids and carbohydrates involved in osmotic adjustment (OA) and energy metabolism by SA, and amino acid metabolism related to OA and stress-defense secondary metabolism by GABA.

  9. The occurrence of abscisic acid in inhibitors B1 and C from immature fruit of Ceratonia siliqua L. (carob) and in commercial carob syrup.

    Science.gov (United States)

    Most, B H; Gaskin, P; Macmillan, J

    1970-03-01

    The presence of abscisic acid in the inhibitors B1 and C from immature carob fruit, whole and minus seed, has been established by thin-layer and gas chromatography and by combined gas chromatography-mass spectrometry. Abscisic acid has been identified in commercial carob syrup by the same means. Most, if not all, of the growth inhibitory activity in these fractions is accounted for as abscisic acid by quantitative gas chromatography as the methyl ester. Trimethylsilylation of abscisic acid with bis (trimethylsilyl) acetamide in pyridine gives two isomeric tris(trimethylsilyl) derivatives.

  10. Homologous Recombination Defective Arabidopsis Mutants Exhibit Enhanced Sensitivity to Abscisic Acid

    Science.gov (United States)

    Roy, Sujit; Das, Kali Pada

    2017-01-01

    Abscisic acid (ABA) acts as an important plant hormone in regulating various aspects of plant growth and developmental processes particularly under abiotic stress conditions. An increased ABA level in plant cells inhibits DNA replication and cell division, causing plant growth retardation. In this study, we have investigated the effects of ABA on the growth responses of some major loss-of-function mutants of DNA double-stand break (DSB) repair genes in Arabidopsis during seed germination and early stages of seedling growth for understanding the role of ABA in the induction of genome instability in plants. A comparative analysis of ABA sensitivity of wild-type Arabidopsis and the knockout mutant lines related to DSB sensors, including atatm, atatr, the non-homologous end joining (NHEJ) pathway genes, and mutants related to homologous recombination (HR) pathway genes showed relatively enhanced sensitivity of atatr and HR-related mutants to ABA treatment. The expression levels of HR-related genes were increased in wild-type Arabidopsis (Col-0) during seed germination and early stages of seedling growth. Immunoblotting experiments detected phosphorylation of histone H2AX in wild-type (Col-0) and DSB repair gene mutants after ABA treatment, indicating the activation of DNA damage response due to ABA treatment. Analyses of DSB repair kinetics using comet assay under neutral condition have revealed comparatively slower DSB repair activity in HR mutants. Overall, our results have provided comprehensive information on the possible effect of ABA on DNA repair machinery in plants and also indicated potential functional involvement of HR pathway in repairing ABA induced DNA damage in Arabidopsis. PMID:28046013

  11. Abscisic Acid Induces Rapid Reductions in Mesophyll Conductance to Carbon Dioxide.

    Directory of Open Access Journals (Sweden)

    Giuseppe Sorrentino

    Full Text Available The rate of photosynthesis (A of plants exposed to water deficit is a function of stomatal (gs and mesophyll (gm conductance determining the availability of CO2 at the site of carboxylation within the chloroplast. Mesophyll conductance often represents the greatest impediment to photosynthetic uptake of CO2, and a crucial determinant of the photosynthetic effects of drought. Abscisic acid (ABA plays a fundamental role in signalling and co-ordination of plant responses to drought; however, the effect of ABA on gm is not well-defined. Rose, cherry, olive and poplar were exposed to exogenous ABA and their leaf gas exchange parameters recorded over a four hour period. Application with ABA induced reductions in values of A, gs and gm in all four species. Reduced gm occurred within one hour of ABA treatment in three of the four analysed species; indicating that the effect of ABA on gm occurs on a shorter timescale than previously considered. These declines in gm values associated with ABA were not the result of physical changes in leaf properties due to altered turgor affecting movement of CO2, or caused by a reduction in the sub-stomatal concentration of CO2 (Ci. Increased [ABA] likely induces biochemical changes in the properties of the interface between the sub-stomatal air-space and mesophyll layer through the actions of cooporins to regulate the transport of CO2. The results of this study provide further evidence that gm is highly responsive to fluctuations in the external environment, and stress signals such as ABA induce co-ordinated modifications of both gs and gm in the regulation of photosynthesis.

  12. Ethephon use and application timing of abscisic acid for improving color of 'Rubi' table grape

    Directory of Open Access Journals (Sweden)

    Sergio Ruffo Roberto

    2013-07-01

    Full Text Available The objective of this work was to evaluate the effect of ethephon and of abscisic acid (ABA application timing on the color of 'Rubi' Table grape. Eight treatments were evaluated: control, without application; ethephon 500 mg L‑1 applied seven days after veraison (7 DAV; and two concentrations of ABA (200 and 400 mg L‑1 arranged with three application timings at 7 DAV, at 15 days before harvest (DBH, and at 7 DAV + 15 DBH. ABA does not modify physical‑chemical characteristics of the cluster and improves the color of grapes, especially when applied twice (7 DAV + 15 DBH at the concentration of 400 mg L‑1.

  13. ATAF1 transcription factor directly regulates abscisic acid biosynthetic gene NCED3 in Arabidopsis thaliana

    DEFF Research Database (Denmark)

    Jensen, Michael Krogh; Lindemose, Søren; De Masi, Federico

    2013-01-01

    ATAF1, an Arabidopsis thaliana NAC transcription factor, plays important roles in plant adaptation to environmental stress and development. To search for ATAF1 target genes, we used protein binding microarrays and chromatin-immunoprecipitation (ChIP). This identified T[A,C,G]CGT[A,G] and TT[A,C,G...... abscisic acid (ABA) phytohormone biosynthetic gene NCED3. ChIP-qPCR and expression analysis showed that ATAF1 binding to the NCED3 promoter correlated with increased NCED3 expression and ABA hormone levels. These results indicate that ATAF1 regulates ABA biosynthesis....

  14. Abscisic acid root and leaf concentration in relation to biomass partitioning in salinized tomato plants.

    Science.gov (United States)

    Lovelli, Stella; Scopa, Antonio; Perniola, Michele; Di Tommaso, Teodoro; Sofo, Adriano

    2012-02-15

    Salinization is one of the most important causes of crop productivity reduction in many areas of the world. Mechanisms that control leaf growth and shoot development under the osmotic phase of salinity are still obscure, and opinions differ regarding the Abscisic acid (ABA) role in regulation of biomass allocation under salt stress. ABA concentration in roots and leaves was analyzed in a genotype of processing tomato under two increasing levels of salinity stress for five weeks: 100 mM NaCl (S10) and 150 mM NaCl (S15), to study the effect of ABA changes on leaf gas exchange and dry matter partitioning of this crop under salinity conditions. In S15, salinization decreased dry matter by 78% and induced significant increases of Na(+) and Cl(-) in both leaves and roots. Dry matter allocated in different parts of plant was significantly different in salt-stressed treatments, as salinization increased root/shoot ratio 2-fold in S15 and 3-fold in S15 compared to the control. Total leaf water potential (Ψ(w)) decreased from an average value of approximately -1.0 MPa, measured on control plants and S10, to -1.17 MPa in S15. In S15, photosynthesis was reduced by 23% and stomatal conductance decreased by 61%. Moreover, salinity induced ABA accumulation both in tomato leaves and roots of the more stressed treatment (S15), where ABA level was higher in roots than in leaves (550 and 312 ng g(-1) fresh weight, respectively). Our results suggest that the dynamics of ABA and ion accumulation in tomato leaves significantly affected both growth and gas exchange-related parameters in tomato. In particular, ABA appeared to be involved in the tomato salinity response and could play an important role in dry matter partitioning between roots and shoots of tomato plants subjected to salt stress.

  15. Identification of Interactions between Abscisic Acid and Ribulose-1,5-Bisphosphate Carboxylase/Oxygenase.

    Directory of Open Access Journals (Sweden)

    Marek M Galka

    Full Text Available Abscisic acid ((+-ABA is a phytohormone involved in the modulation of developmental processes and stress responses in plants. A chemical proteomics approach using an ABA mimetic probe was combined with in vitro assays, isothermal titration calorimetry (ITC, x-ray crystallography and in silico modelling to identify putative (+-ABA binding-proteins in crude extracts of Arabidopsis thaliana. Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco was identified as a putative ABA-binding protein. Radiolabelled-binding assays yielded a Kd of 47 nM for (+-ABA binding to spinach Rubisco, which was validated by ITC, and found to be similar to reported and experimentally derived values for the native ribulose-1,5-bisphosphate (RuBP substrate. Functionally, (+-ABA caused only weak inhibition of Rubisco catalytic activity (Ki of 2.1 mM, but more potent inhibition of Rubisco activation (Ki of ~ 130 μM. Comparative structural analysis of Rubisco in the presence of (+-ABA with RuBP in the active site revealed only a putative low occupancy (+-ABA binding site on the surface of the large subunit at a location distal from the active site. However, subtle distortions in electron density in the binding pocket and in silico docking support the possibility of a higher affinity (+-ABA binding site in the RuBP binding pocket. Overall we conclude that (+-ABA interacts with Rubisco. While the low occupancy (+-ABA binding site and weak non-competitive inhibition of catalysis may not be relevant, the high affinity site may allow ABA to act as a negative effector of Rubisco activation.

  16. Patterns of auxin and abscisic acid movement in the tips of gravistimulated primary roots of maize

    Science.gov (United States)

    Young, L. M.; Evans, M. L.

    1996-01-01

    Because both abscisic acid (ABA) and auxin (IAA) have been suggested as possible chemical mediators of differential growth during root gravitropism, we compared with redistribution of label from applied 3H-IAA and 3H-ABA during maize root gravitropism and examined the relative basipetal movement of 3H-IAA and 3H-ABA applied to the caps of vertical roots. Lateral movement of 3H-ABA across the tips of vertical roots was non-polar and about 2-fold greater than lateral movement of 3H-IAA (also non-polar). The greater movement of ABA was not due to enhanced uptake since the uptake of 3H-IAA was greater than that of 3H-ABA. Basipetal movement of label from 3H-IAA or 3H-ABA applied to the root cap was determined by measuring radioactivity in successive 1 mm sections behind the tip 90 minutes after application. ABA remained largely in the first mm (point of application) whereas IAA was concentrated in the region 2-4 mm from the tip with substantial levels found 7-8 mm from the tip. Pretreatment with inhibitors of polar auxin transport decreased both gravicurvature and the basipetal movement of IAA. When roots were placed horizontally, the movement of 3H-IAA from top to bottom across the cap was enhanced relative to movement from bottom to top whereas the pattern of movement of label from 3H-ABA was unaffected. These results are consistent with the hypothesis that IAA plays a role in root gravitropism but contrary to the idea that gravi-induced asymmetric distribution of ABA contributes to the response.

  17. Exogenous Abscisic Acid Mimics Cold Acclimation for Cacti Differing in Freezing Tolerance.

    Science.gov (United States)

    Loik, M. E.; Nobel, P. S.

    1993-11-01

    The responses to low temperature were determined for two species of cacti sensitive to freezing, Ferocactus viridescens and Opuntia ficus-indica, and a cold hardy species, Opuntia fragilis. Fourteen days after shifting the plants from day/night air temperatures of 30/20[deg]C to 10/0[deg]C, the chlorenchyma water content decreased only for O. fragilis. This temperature shift caused the freezing tolerance (measured by vital stain uptake) of chlorenchyma cells to be enhanced only by about 2.0[deg]C for F. viridescens and O. ficus-indica but by 14.6[deg]C for O. fragilis. Also, maintenance of high water content by injection of water into plants at 10/0[deg]C reversed the acclimation. The endogenous abscisic acid (ABA) concentration was below 0.4 pmol g-1 fresh weight at 30/20[deg]C, but after 14 d at 10/0[deg]C it increased to 84 pmol g-1 fresh weight for O. ficus-indica and to 49 pmol g-1 fresh weight for O. fragilis. Four days after plants were sprayed with 7.5 x 10-5 M ABA at 30/20[deg]C, freezing tolerance was enhanced by 0.5[deg]C for F. viridescens, 4.1[deg]C for O. ficus-indica, and 23.4[deg]C for O. fragilis. Moreover, the time course for the change in freezing tolerance over 14 d was similar for plants shifted to low temperatures as for plants treated with exogenous ABA at moderate temperatures. Decreases in plant water content and increases in ABA concentration may be important for low-temperature acclimation by cacti, especially O. fragilis, which is widely distributed in Canada and the United States.

  18. Reactive oxygen species are involved in gibberellin/abscisic acid signaling in barley aleurone cells.

    Science.gov (United States)

    Ishibashi, Yushi; Tawaratsumida, Tomoya; Kondo, Koji; Kasa, Shinsuke; Sakamoto, Masatsugu; Aoki, Nozomi; Zheng, Shao-Hui; Yuasa, Takashi; Iwaya-Inoue, Mari

    2012-04-01

    Reactive oxygen species (ROS) act as signal molecules for a variety of processes in plants. However, many questions about the roles of ROS in plants remain to be clarified. Here, we report the role of ROS in gibberellin (GA) and abscisic acid (ABA) signaling in barley (Hordeum vulgare) aleurone cells. The production of hydrogen peroxide (H2O2), a type of ROS, was induced by GA in aleurone cells but suppressed by ABA. Furthermore, exogenous H2O2 appeared to promote the induction of α-amylases by GA. In contrast, antioxidants suppressed the induction of α-amylases. Therefore, H2O2 seems to function in GA and ABA signaling, and in regulation of α-amylase production, in aleurone cells. To identify the target of H2O2 in GA and ABA signaling, we analyzed the interrelationships between H2O2 and DELLA proteins Slender1 (SLN1), GA-regulated Myb transcription factor (GAmyb), and ABA-responsive protein kinase (PKABA) and their roles in GA and ABA signaling in aleurone cells. In the presence of GA, exogenous H2O2 had little effect on the degradation of SLN1, the primary transcriptional repressor mediating GA signaling, but it promoted the production of the mRNA encoding GAMyb, which acts downstream of SLN1 and involves induction of α-amylase mRNA. Additionally, H2O2 suppressed the production of PKABA mRNA, which is induced by ABA:PKABA represses the production of GAMyb mRNA. From these observations, we concluded that H2O2 released the repression of GAMyb mRNA by PKABA and consequently promoted the production of α-amylase mRNA, thus suggesting that the H2O2 generated by GA in aleurone cells is a signal molecule that antagonizes ABA signaling.

  19. Abscisic Acid accumulates at positive turgor potential in excised soybean seedling growing zones.

    Science.gov (United States)

    Creelman, R A; Mullet, J E

    1991-04-01

    Abscisic acid (ABA) accumulated in soybean (Glycine max [L.] Merr. cv Williams) hypocotyl elongating regions when seedlings were transferred to low water potential vermiculite (Psi = -0.3 megapascals) even though positive turgor is retained in this tissue. Accumulation of ABA in growing zones could occur from de novo biosynthesis within this tissue or transport from adjacent nongrowing zones. Both growing and nongrowing hypocotyl and root tissues accumulated significant levels of ABA when excised and dehydrated to reduce turgor. Surprisingly, excised growing zones (which experienced no water loss) also accumulated ABA when incubated in darkness for 4 hours at 100% relative humidity and 29 degrees C. Induction of ABA accumulation in the excised elongating region of the hypocotyl was not caused by disruption of root pressure or wounding. While excision of hypocotyl elongating regions induced ABA accumulation, no change in either extensin or p33 mRNA levels was observed. Accumulation of extensin or p33 mRNA required more severe wounding. This suggests that ABA is not involved in the response of these genes in wounded tissue and that wound signals are not causing ABA accumulation in excised tissue. Accumulation of ABA in excised elongating regions was correlated with growth inhibition and a decline in turgor to the yield threshold (Psi;(p) = 0.37 megapascals; R Matyssek, S Maruyama, JS Boyer [1988] Plant Physiol 86: 1163-1167). Inhibiting hypocotyl growth by transferring seedlings to lower temperatures or light did not cause ABA accumulation. We conclude that induction of ABA accumulation in growing zones is more sensitive to changes in turgor than the induction which occurs in mature tissues.

  20. Abscisic acid-cytokinin antagonism modulates resistance against pseudomonas syringae in Tobacco

    DEFF Research Database (Denmark)

    Grosskinsky, Dominik Kilian; van der Graaff, Eric; Roitsch, Thomas Georg

    2014-01-01

    Phytohormones are known as essential regulators of plant defenses, with ethylene, jasmonic acid, and salicylic acid as the central immunity backbone, while other phytohormones have been demonstrated to interact with this. Only recently, a function of the classic phytohormone cytokinin in plant...... immunity has been described in Arabidopsis, rice, and tobacco. Although interactions of cytokinins with salicylic acid and auxin have been indicated, the complete network of cytokinin interactions with other immunity-relevant phytohormones is not yet understood. Therefore, we studied the interaction...... of kinetin and abscisic acid as a negative regulator of plant immunity to modulate resistance in tobacco against Pseudomonas syringae. By analyzing infection symptoms, pathogen proliferation, and accumulation of the phytoalexin scopoletin as a key mediator of kinetin-induced resistance in tobacco...

  1. Mutations in the Arabidopsis Lst8 and Raptor genes encoding partners of the TOR complex, or inhibition of TOR activity decrease abscisic acid (ABA) synthesis.

    Science.gov (United States)

    Kravchenko, Alena; Citerne, Sylvie; Jéhanno, Isabelle; Bersimbaev, Rakhmetkazhi I; Veit, Bruce; Meyer, Christian; Leprince, Anne-Sophie

    2015-11-27

    The Target of Rapamycin (TOR) kinase regulates essential processes in plant growth and development by modulation of metabolism and translation in response to environmental signals. In this study, we show that abscisic acid (ABA) metabolism is also regulated by the TOR kinase. Indeed ABA hormone level strongly decreases in Lst8-1 and Raptor3g mutant lines as well as in wild-type (WT) Arabidopsis plants treated with AZD-8055, a TOR inhibitor. However the growth and germination of these lines are more sensitive to exogenous ABA. The diminished ABA hormone accumulation is correlated with lower transcript levels of ZEP, NCED3 and AAO3 biosynthetic enzymes, and higher transcript amount of the CYP707A2 gene encoding a key-enzyme in abscisic acid catabolism. These results suggest that the TOR signaling pathway is implicated in the regulation of ABA accumulation in Arabidopsis.

  2. Effects of copper on chlorophyll, proline, protein and abscisic acid level of sunflower (Helianthus annuus L.) seedlings.

    Science.gov (United States)

    Zengin, Fikriye Kirbag; Kirbag, Sevda

    2007-07-01

    The effect of copperchloride (CuCl2) on the level of chlorophyll (a+b), proline, protein and abscisic acid in sunflower (Helianthus annuus L.) seedlings were investigated Control and copper treated (0.4, 0.5 and 0.6 mM) seedlings were grown for ten days in Hoagland solution. Abscisic acid content was determined in root, shoot and leaf tissues of seedlings by HPLC. Copper stress caused significant increase of the abscisic acid contents in roots, shoots and leaves of seedlings. The increase was dependent on the copper salt concentration. Enhanced accumulation of proline in the leaves of seedlings exposed to copper was determined, as well as a decrease of chlorophyll (a+b) and total protein (p Helianthus annuus L.) seedlings. Thus, we assumed that copper levels increase above some critical points seedling growth get negative effects. This assumption is in line with previous findings.

  3. Effect of abscisic acid, Paclobutrazol and Salicylic acid on the growth and Pigment variation in Solanum Trilobatum (l

    Directory of Open Access Journals (Sweden)

    D. Nivedithadevi

    2012-09-01

    Full Text Available Solanum trilobatum (Family: Solanaceae is one of the common Indian medicinal plants and it has been used in traditional medicine for many centuries. This plant is a thorny creeper with bluish violet flower, more commonly available in southern India has been used traditional in Siddha system of medicines to treat various diseases. The roots, leaves, berries and flowers are used for cough. The decoction of entire Solanum trilobatum plant is used to treat acute and chronic bronchitis. It has been widely used to treat respiratory disorders. This plant is commonly used to treat asthma, cough, dysonoea, chronic febrile infections and difficult parturition. The constituents of this plant include sobatum, -solamarine, solanine, solasodine, glycoalkaloid, diosogenin and tomatidine. Plant growth regulators are substance that influences physiological processes of plants at very low concentration. Abscisic acid is a many important plant growth development processed. Paclobutrazol is a triazolic group of fungicide which has plant growth regulating properties. Salicylic acid is phenolic phytohormones and is formed in plants with role of plant growth and development. The given treatments were started at 70th day followed by 80th, 90th and 100th days. The groups were treated with respect growth hormones by spraying method. After 10th day, the plants were harvested for further analysis. On over all physical assessment plants treated with paclobutrazol were found to have more whole plant fresh weight, dry weight, root length and stem length followed by abscisic acid and salicylic acid. After the physical evaluation, the leaves were collected from each group for pigment analysis. Chlorophyll, carotenoid, anthocyanin and xanthophylls pigment contents were increased in abscisic acid followed by paclobutrazol and salicylic acid.

  4. Regulation of Water Deficit-Induced Abscisic Acid Accumulation by Apoplastic Ascorbic Acid in Maize Seedlings

    Institute of Scientific and Technical Information of China (English)

    Jian-Fang HU; Gui-Fen LI; Zhi-Hui GAO; Lin CHEN; Hui-Bo REN; Wen-Suo JIA

    2005-01-01

    Water deficit-induced abscisic acid (ABA) accumulation is one of the most important stress signaling pathways in plant cells. Redox regulation of cellular signaling has currently attracted particular attention, but much less is known about its roles and mechanisms in plant signaling. Herein, we report that water deficit-induced ABA accumulation could be regulated by ascorbic acid (AA)-controlled redox status in leave apoplast. The AA content in non-stressed leaves was approximately 3 μmol/g FW, corresponding to a mean concentration of 3 mmol/L in a whole cell. Because AA is mainly localized in the cytosol and chloroplasts, the volume of which is much smaller than that of the whole cell, AA content in cytosolic and chloroplast compartments should be much higher than 3 mmol/L. Water deficit-induced ABA accumulation in both leaf and root tissues of maize seedlings was significantly inhibited by AA and reduced glutathione (GSH) at concentrations of 500 μmol/L and was completely blocked by 50 mmol/L AA and GSH. These results suggest that the AA-induced inhibition of ABA accumulation should not occur at sites where AA exists in high concentrations. Although water deficit led to a small increase in the dehydroascorbic acid (DHA) content, no significant changes in AA content were observed in either leaf or root tissues. When compared with the whole leaf cell, the AA content in the apoplastic compartment was much lower (i.e.approximately 70 nmol/g FW, corresponding to 0.7 mmol/L). Water deficit induced a significant decrease (approximately 2.5-fold) in the AA content and an increase (approximately 3.4-fold) in the DHA content in the apoplastic compartment, thus leading to a considerably decreased redox status there, which may have contributed to the relief of AA-induced inhibition of ABA accumulation, alternatively, promoting water deficit-induced ABA accumulation. Reactive oxygen species (ROS) could not mimic water deficit in inducing ABA accumulation, suggesting that

  5. Effect of abscisic and gibberellic acids on malate synthase transcripts in germinating castor bean seeds.

    Science.gov (United States)

    Rodriguez, D; Dommes, J; Northcote, D H

    1987-05-01

    Several clones complementary to malate synthase mRNA have been identified in a complementary-DNA library to mRNA from castor bean endosperm. One of these clones has been used as a probe to measure levels of transcripts during seed germination and the effects of gibberellic acid and abscisic acid on these levels have been examined.Malate synthase transcripts increased during germination and GA3 advanced their appearance in the endosperm. Exogenously applied ABA inhibited the accumulation of transcripts over a time course of germination but the addition of GA3 counteracted its inhibitory effects. The data confirmed previous reports which indicated that the action of both growth regulators was on transcript accumulation and that there is a coordinated induction of the enzymes involved in the lipid metabolism in oil seeds.

  6. QTLs and candidate genes for desiccation and abscisic acid content in maize kernels

    Directory of Open Access Journals (Sweden)

    Charcosset Alain

    2010-01-01

    Full Text Available Abstract Background Kernel moisture at harvest is an important trait since a low value is required to prevent unexpected early germination and ensure seed preservation. It is also well known that early germination occurs in viviparous mutants, which are impaired in abscisic acid (ABA biosynthesis. To provide some insight into the genetic determinism of kernel desiccation in maize, quantitative trait loci (QTLs were detected for traits related to kernel moisture and ABA content in both embryo and endosperm during kernel desiccation. In parallel, the expression and mapping of genes involved in kernel desiccation and ABA biosynthesis, were examined to detect candidate genes. Results The use of an intermated recombinant inbred line population allowed for precise QTL mapping. For 29 traits examined in an unreplicated time course trial of days after pollination, a total of 78 QTLs were detected, 43 being related to kernel desiccation, 15 to kernel weight and 20 to ABA content. Multi QTL models explained 35 to 50% of the phenotypic variation for traits related to water status, indicating a large genetic control amenable to breeding. Ten of the 20 loci controlling ABA content colocated with previously detected QTLs controlling water status and ABA content in water stressed leaves. Mapping of candidate genes associated with kernel desiccation and ABA biosynthesis revealed several colocations between genes with putative functions and QTLs. Parallel investigation via RT-PCR experiments showed that the expression patterns of the ABA-responsive Rab17 and Rab28 genes as well as the late embryogenesis abundant Emb5 and aquaporin genes were related to desiccation rate and parental allele effect. Database searches led to the identification and mapping of two zeaxanthin epoxidase (ZEP and five novel 9-cis-epoxycarotenoid dioxygenase (NCED related genes, both gene families being involved in ABA biosynthesis. The expression of these genes appeared independent in

  7. Transcriptional regulatory programs underlying barley germination and regulatory functions of Gibberellin and abscisic acid

    Directory of Open Access Journals (Sweden)

    Lin Li

    2011-06-01

    Full Text Available Abstract Background Seed germination is a complex multi-stage developmental process, and mainly accomplished through concerted activities of many gene products and biological pathways that are often subjected to strict developmental regulation. Gibberellins (GA and abscisic acid (ABA are two key phytohormones regulating seed germination and seedling growth. However, transcriptional regulatory networks underlying seed germination and its associated biological pathways are largely unknown. Results The studies examined transcriptomes of barley representing six distinct and well characterized germination stages and revealed that the transcriptional regulatory program underlying barley germination was composed of early, late, and post-germination phases. Each phase was accompanied with transcriptional up-regulation of distinct biological pathways. Cell wall synthesis and regulatory components including transcription factors, signaling and post-translational modification components were specifically and transiently up-regulated in early germination phase while histone families and many metabolic pathways were up-regulated in late germination phase. Photosynthesis and seed reserve mobilization pathways were up-regulated in post-germination phase. However, stress related pathways and seed storage proteins were suppressed through the entire course of germination. A set of genes were transiently up-regulated within three hours of imbibition, and might play roles in initiating biological pathways involved in seed germination. However, highly abundant transcripts in dry barley and Arabidopsis seeds were significantly conserved. Comparison with transcriptomes of barley aleurone in response to GA and ABA identified three sets of germination responsive genes that were regulated coordinately by GA, antagonistically by ABA, and coordinately by GA but antagonistically by ABA. Major CHO metabolism, cell wall degradation and protein degradation pathways were up

  8. Abscisic acid controls embryo growth potential and endosperm cap weakening during coffee (Coffea arabica cv. Rubi) seed germination

    NARCIS (Netherlands)

    Silva, da E.A.A.; Toorop, P.E.; Aelst, van A.C.; Hilhorst, H.W.M.

    2004-01-01

    The mechanism and regulation of coffee seed germination were studied in Coffea arabica L. cv. Rubi. The coffee embryo grew inside the endosperm prior to radicle protrusion and abscisic acid (ABA) inhibited the increase in its pressure potential. There were two steps of endosperm cap weakening. An in

  9. Molecular mechanisms in the activation of abscisic acid receptor PYR1.

    Science.gov (United States)

    Dorosh, Lyudmyla; Kharenko, Olesya A; Rajagopalan, Nandhakishore; Loewen, Michele C; Stepanova, Maria

    2013-01-01

    The pyrabactin resistance 1 (PYR1)/PYR1-like (PYL)/regulatory component of abscisic acid (ABA) response (RCAR) proteins comprise a well characterized family of ABA receptors. Recent investigations have revealed two subsets of these receptors that, in the absence of ABA, either form inactive homodimers (PYR1 and PYLs 1-3) or mediate basal inhibition of downstream target type 2C protein phosphatases (PP2Cs; PYLs 4-10) respectively in vitro. Addition of ABA has been shown to release the apo-homodimers yielding ABA-bound monomeric holo-receptors that can interact with PP2Cs; highlighting a competitive-interaction process. Interaction selectivity has been shown to be mediated by subtle structural variations of primary sequence and ligand binding effects. Now, the dynamical contributions of ligand binding on interaction selectivity are investigated through extensive molecular dynamics (MD) simulations of apo and holo-PYR1 in monomeric and dimeric form as well as in complex with a PP2C, homology to ABA insensitive 1 (HAB1). Robust comparative interpretations were enabled by a novel essential collective dynamics approach. In agreement with recent experimental findings, our analysis indicates that ABA-bound PYR1 should efficiently bind to HAB1. However, both ABA-bound and ABA-extracted PYR1-HAB1 constructs have demonstrated notable similarities in their dynamics, suggesting that apo-PYR1 should also be able to make a substantial interaction with PP2Cs, albeit likely with slower complex formation kinetics. Further analysis indicates that both ABA-bound and ABA-free PYR1 in complex with HAB1 exhibit a higher intra-molecular structural stability and stronger inter-molecular dynamic correlations, in comparison with either holo- or apo-PYR1 dimers, supporting a model that includes apo-PYR1 in complex with HAB1. This possibility of a conditional functional apo-PYR1-PP2C complex was validated in vitro. These findings are generally consistent with the competitive-interaction model

  10. Molecular mechanisms in the activation of abscisic acid receptor PYR1.

    Directory of Open Access Journals (Sweden)

    Lyudmyla Dorosh

    Full Text Available The pyrabactin resistance 1 (PYR1/PYR1-like (PYL/regulatory component of abscisic acid (ABA response (RCAR proteins comprise a well characterized family of ABA receptors. Recent investigations have revealed two subsets of these receptors that, in the absence of ABA, either form inactive homodimers (PYR1 and PYLs 1-3 or mediate basal inhibition of downstream target type 2C protein phosphatases (PP2Cs; PYLs 4-10 respectively in vitro. Addition of ABA has been shown to release the apo-homodimers yielding ABA-bound monomeric holo-receptors that can interact with PP2Cs; highlighting a competitive-interaction process. Interaction selectivity has been shown to be mediated by subtle structural variations of primary sequence and ligand binding effects. Now, the dynamical contributions of ligand binding on interaction selectivity are investigated through extensive molecular dynamics (MD simulations of apo and holo-PYR1 in monomeric and dimeric form as well as in complex with a PP2C, homology to ABA insensitive 1 (HAB1. Robust comparative interpretations were enabled by a novel essential collective dynamics approach. In agreement with recent experimental findings, our analysis indicates that ABA-bound PYR1 should efficiently bind to HAB1. However, both ABA-bound and ABA-extracted PYR1-HAB1 constructs have demonstrated notable similarities in their dynamics, suggesting that apo-PYR1 should also be able to make a substantial interaction with PP2Cs, albeit likely with slower complex formation kinetics. Further analysis indicates that both ABA-bound and ABA-free PYR1 in complex with HAB1 exhibit a higher intra-molecular structural stability and stronger inter-molecular dynamic correlations, in comparison with either holo- or apo-PYR1 dimers, supporting a model that includes apo-PYR1 in complex with HAB1. This possibility of a conditional functional apo-PYR1-PP2C complex was validated in vitro. These findings are generally consistent with the competitive

  11. Isolation and Crystal Structure of 1′,4′-Trans-diol of Abscisic Acid

    Institute of Scientific and Technical Information of China (English)

    WANG Tian-Shan; ZHOU Jin-Yan; TAN Hong

    2006-01-01

    1 ′,4′-Trans-diol of abscisic acid was isolated from botrytis cinerea as a colorless crystal. The molecular and crystal structures have been determined by X-ray diffraction analysis. It crystallizes in orthorhombic system, space group P212121 with a = 6.724(3), b = 17.559(6), c =12.265(2) (A), a = β = y = 90°, V = 1448.1(8) (A)3, Z = 4, Dx = 1.222 g/cm3, F(000) = 576 and μ(MoKa) = 0.087 mm-1. The final R = 0.0628 and wR = 0.1604 for 2501 independent reflections with Rint = 0.0160 and 1679 observed reflections with I >2σ(Ⅰ). There are three intermolecular hydrogen bonds in a unit cell.

  12. Involvement of Polyamine Oxidase in Abscisic Acid induced Cytosolic Antioxidant Defense in Leaves of Maize

    Institute of Scientific and Technical Information of China (English)

    Beibei Xue; Aying Zhang; Mingyi Jiang

    2009-01-01

    Using pharmacological and biochemical approaches, the role of maize polyamine oxidase (MPAO) in abscisic acid (ABA)induced antioxidant defense in leaves of maize (Zea mays L.) plants was investigated. Exogenous ABA treatment enhanced the expression of the MPAO gene and the activities of apoplastic MPAO. Pretreatment with two different inhibitors for apoplastic MPAO partly reduced hydrogen peroxide (H2O2) accumulation induced by ABA and blocked the ABA-induced expression of the antioxidant genes superoxide dismutase 4 and cytosolic ascorbate peroxidase and the activities of the cytosolic antioxidant enzymes. Treatment with spermidine, the optimum substrate of MPAO, also induced the expression and the activities of the antioxidant enzymes, and the upregulation of the antioxidant enzymes was prevented by two inhibitors of MPAO and two scavengers of H2O2. These results suggest that MPAO contributes to ABA-induced cytosolic antioxidant defense through H2O2, a Spd catabolic product.

  13. Exogenous abscisic acid application during grain filling in winter wheat improves cold tolerance of offspring's seedlings

    DEFF Research Database (Denmark)

    Li, X.; Cai, J.; Liu, Fulai

    2014-01-01

    Low temperature seriously depresses seed germination and seedling growth in winter wheat (Triticum aestivum L.). In this study, wheat plants were sprayed with abscisic acid (ABA) and fluridone (inhibitor of ABA biosynthesis) at 19 days after anthesis (DAA) and repeated at 26 DAA. The seeds of those...... plants were harvested, and seed germination and offspring's seedling growth under low temperature were evaluated. The results showed that exogenous ABA application decreased seed weight and slightly reduced seed set and seed number per spike. Under low temperature, seeds from ABA-treated plants showed...... reduced germination rate, germination index, growth of radicle and coleoptile, amylase activity and depressed starch degradation as compared with seeds from non-ABA-treated plants; however, activities of the antioxidant enzymes in both germinating seeds and seedling were enhanced from those exposed...

  14. ABSCISIC ACID-INSENSITIVE 4 negatively regulates flowering through directly promoting Arabidopsis FLOWERING LOCUS C transcription

    Science.gov (United States)

    Shu, Kai; Chen, Qian; Wu, Yaorong; Liu, Ruijun; Zhang, Huawei; Wang, Shengfu; Tang, Sanyuan; Yang, Wenyu; Xie, Qi

    2016-01-01

    During the life cycle of a plant, one of the major biological processes is the transition from the vegetative to the reproductive stage. In Arabidopsis, flowering time is precisely controlled by extensive environmental and internal cues. Gibberellins (GAs) promote flowering, while abscisic acid (ABA) is considered as a flowering suppressor. However, the detailed mechanism through which ABA inhibits the floral transition is poorly understood. Here, we report that ABSCISIC ACID-INSENSITIVE 4 (ABI4), a key component in the ABA signalling pathway, negatively regulates floral transition by directly promoting FLOWERING LOCUS C (FLC) transcription. The abi4 mutant showed the early flowering phenotype whereas ABI4-overexpressing (OE-ABI4) plants had delayed floral transition. Consistently, quantitative reverse transcription–PCR (qRT–PCR) assay revealed that the FLC transcription level was down-regulated in abi4, but up-regulated in OE-ABI4. The change in FT level was consistent with the pattern of FLC expression. Chromatin immunoprecipitation-qPCR (ChIP-qPCR), electrophoretic mobility shift assay (EMSA), and tobacco transient expression analysis showed that ABI4 promotes FLC expression by directly binding to its promoter. Genetic analysis demonstrated that OE-ABI4::flc-3 could not alter the flc-3 phenotype. OE-FLC::abi4 showed a markedly delayed flowering phenotype, which mimicked OE-FLC::WT, and suggested that ABI4 acts upstream of FLC in the same genetic pathway. Taken together, these findings suggest that ABA inhibits the floral transition by activating FLC transcription through ABI4. PMID:26507894

  15. Heat-stable proteins and abscisic acid action in barley aleurone cells

    Energy Technology Data Exchange (ETDEWEB)

    Jacobsen, J.V. (CSIRO, Canberra (Australia)); Shaw, D.C. (Australian National Univ., Canberra (Australia))

    1989-12-01

    ({sup 35}S)Methionine labeling experiments showed that abscisic acid (ABA) induced the synthesis of at least 25 polypeptides in mature barley (Hordeum vulgare) aleurone cells. The polypeptides were not secreted. Whereas most of the proteins extracted from aleurone cells were coagulated by heating to 100{degree}C for 10 minutes, most of the ABA-induced polypeptides remained in solution (heat-stable). ABA had little effect on the spectrum of polypeptides that were synthesized and secreted by aleurone cells, and most of these secreted polypeptides were also heat-stable. Coomassie blue staining of sodium dodecyl sulfate polyacrylamide gels indicated that ABA-induced polypeptides already occurred in high amounts in mature aleurone layers having accumulated during grain development. About 60% of the total protein extracted from mature aleurone was heat stable. Amino acid analyses of total preparations of heat-stable and heat-labile proteins showed that, compared to heat-labile proteins, heat-stable intracellular proteins were characterized by higher glutamic acid/glutamine (Glx) and glycine levels and lower levels of neutral amino acids. Secreted heat-stable proteins were rich in Glx and proline. The possibilities that the accumulation of the heat-stable polypeptides during grain development is controlled by ABA and that the function of these polypeptides is related to their abundance and extraordinary heat stability are considered.

  16. Abscisic Acid Signaling and Abiotic Stress Tolerance in Plants: A Review on Current Knowledge and Future Prospects

    Science.gov (United States)

    Vishwakarma, Kanchan; Upadhyay, Neha; Kumar, Nitin; Yadav, Gaurav; Singh, Jaspreet; Mishra, Rohit K.; Kumar, Vivek; Verma, Rishi; Upadhyay, R. G.; Pandey, Mayank; Sharma, Shivesh

    2017-01-01

    Abiotic stress is one of the severe stresses of environment that lowers the growth and yield of any crop even on irrigated land throughout the world. A major phytohormone abscisic acid (ABA) plays an essential part in acting toward varied range of stresses like heavy metal stress, drought, thermal or heat stress, high level of salinity, low temperature, and radiation stress. Its role is also elaborated in various developmental processes including seed germination, seed dormancy, and closure of stomata. ABA acts by modifying the expression level of gene and subsequent analysis of cis- and trans-acting regulatory elements of responsive promoters. It also interacts with the signaling molecules of processes involved in stress response and development of seeds. On the whole, the stress to a plant can be susceptible or tolerant by taking into account the coordinated activities of various stress-responsive genes. Numbers of transcription factor are involved in regulating the expression of ABA responsive genes by acting together with their respective cis-acting elements. Hence, for improvement in stress-tolerance capacity of plants, it is necessary to understand the mechanism behind it. On this ground, this article enlightens the importance and role of ABA signaling with regard to various stresses as well as regulation of ABA biosynthetic pathway along with the transcription factors for stress tolerance. PMID:28265276

  17. Control of macaw palm seed germination by the gibberellin/abscisic acid balance.

    Science.gov (United States)

    Bicalho, E M; Pintó-Marijuan, M; Morales, M; Müller, M; Munné-Bosch, S; Garcia, Q S

    2015-09-01

    The hormonal mechanisms involved in palm seed germination are not fully understood. To better understand how germination is regulated in Arecaceae, we used macaw palm (Acrocomia aculeata (Jacq.) Lodd. Ex Mart.) seed as a model. Endogenous hormone concentrations, tocopherol and tocotrienol and lipid peroxidation during germination were studied separately in the embryo and endosperm. Evaluations were performed in dry (D), imbibed (I), germinated (G) and non-germinated (NG) seeds treated (+GA3 ) or not treated (control) with gibberellins (GA). With GA3 treatment, seeds germinated faster and to a higher percentage than control seeds. The +GA3 treatment increased total bioactive GA in the embryo during germination relative to the control. Abscisic acid (ABA) concentrations decreased gradually from D to G in both tissues. Embryos of G seeds had a lower ABA content than NG seeds in both treatments. The GA/ABA ratio in the embryo was significantly higher in G than NG seeds. The +GA3 treatment did not significantly affect the GA/ABA ratio in either treatment. Cytokinin content increased from dry to germinated seeds. Jasmonic acid (JA) increased and 1-aminocyclopropane-1-carboylic acid (ACC) decreased after imbibition. In addition, α-tocopherol and α-tocotrienol decreased, while lipid peroxidation increased in the embryo during germination. We conclude that germination in macaw palm seed involves reductions in ABA content and, consequently, increased GA/ABA in the embryo. Furthermore, the imbibition process generates oxidative stress (as observed by changes in vitamin E and MDA).

  18. Proteome analysis of Norway maple (Acer platanoides L. seeds dormancy breaking and germination: influence of abscisic and gibberellic acids

    Directory of Open Access Journals (Sweden)

    Pawłowski Tomasz A

    2009-05-01

    Full Text Available Abstract Background Seed dormancy is controlled by the physiological or structural properties of a seed and the external conditions. It is induced as part of the genetic program of seed development and maturation. Seeds with deep physiological embryo dormancy can be stimulated to germinate by a variety of treatments including cold stratification. Hormonal imbalance between germination inhibitors (e.g. abscisic acid and growth promoters (e.g. gibberellins is the main cause of seed dormancy breaking. Differences in the status of hormones would affect expression of genes required for germination. Proteomics offers the opportunity to examine simultaneous changes and to classify temporal patterns of protein accumulation occurring during seed dormancy breaking and germination. Analysis of the functions of the identified proteins and the related metabolic pathways, in conjunction with the plant hormones implicated in seed dormancy breaking, would expand our knowledge about this process. Results A proteomic approach was used to analyse the mechanism of dormancy breaking in Norway maple seeds caused by cold stratification, and the participation of the abscisic (ABA and gibberellic (GA acids. Forty-four proteins showing significant changes were identified by mass spectrometry. Of these, eight spots were identified as water-responsive, 18 spots were ABA- and nine GA-responsive and nine spots were regulated by both hormones. The classification of proteins showed that most of the proteins associated with dormancy breaking in water were involved in protein destination. Most of the ABA- and GA-responsive proteins were involved in protein destination and energy metabolism. Conclusion In this study, ABA was found to mostly down-regulate proteins whereas GA up-regulated proteins abundance. Most of the changes were observed at the end of stratification in the germinated seeds. This is the most active period of dormancy breaking when seeds pass from the quiescent

  19. Analysis of Global Expression Profiles of Arabidopsis Genes Under Abscisic Acid and H2O2 Applications

    Institute of Scientific and Technical Information of China (English)

    Peng-Cheng Wang; Yan-Yan Du; Guo-Yong An; Yun Zhou; Chen Miao; Chun-Peng Song

    2006-01-01

    To gain insight into the coordination of gene expression profiles under abscisic acid (ABA) and H2O2 applications,global changes in gene expression in response to ABA and H2O2 in Arabidopsis seedlings were investigated using GeneChip (Santa Clara, CA, USA) arrays. Among over 24 000 genes present in the arrays, 459 transcripts were found to be significantly increased, whereas another 221 decreased following H2O2 treatment compared with control. Similar to treatment with H2O2, ABA treatment elevated the transcription of 391 genes and repressed that of 322 genes. One hundred and forty-three upregulated genes and 75 downregulated genes were shared between the two treatments and these genes were mainly involved in metabolism, signal transduction, transcription, defense, and resistance. Only two genes, which encode an APETALA2/dehydration-responsive element binding protein (AP2/DREBP) family transcriptional factor and a late embryogenesisabundant protein, were downregulated by H2O2, but upregulated by ABA. These results suggest that, similar to ABA, H2O2 plays a global role in gene transcription of Arabidopsisseedlings. The transcriptional responses induced by the application of exogenous ABA and H2O2 overlapped substantially. These two treatments regulated most of the downstream genes in a coordinated manner.

  20. Genetic interaction of two abscisic acid signaling regulators, HY5 and FIERY1, in mediating lateral root formation

    KAUST Repository

    Chen, Hao

    2011-01-01

    Root architecture is continuously shaped in a manner that helps plants to better adapt to the environment. Gene regulation at the transcriptional or post-transcriptional levels largely controls this environmental response. Recently, RNA silencing has emerged as an important player in gene regulation and is involved in many aspects of plant development, including lateral root formation. In a recent study, we found that FIERY1, a bifunctional abiotic stress and abscisic acid (ABA) signaling regulator and an endogenous RNA silencing suppressor, mediates auxin response during lateral root formation in Arabidopsis. We proposed that FRY1 regulates lateral root development through its activity on adenosine 3,5-bisphosphate (PAP), a strong inhibitor of exoribonucleases (XRNs). Interestingly, some of the phenotypes of fry1, such as enhanced response to light in repressing hypocotyl elongation and hypersensitivity to ABA in lateral root growth, are opposite to those of another light- and ABA-signaling mutant, hy5. Here we analyzed the hy5 fry1 double mutant for root and hypocotyl growth. We found that the hy5 mutation can suppress the enhanced light sensitivity in fry1 hypocotyl elongation and restore the lateral root formation. The genetic interaction between HY5 and FRY1 indicates that HY5 and FRY1 may act in overlapping pathways that mediate light signaling and lateral root development. © 2011 Landes Bioscience.

  1. Effects of exogenous abscisic acid on yield, antioxidant capacities, and phytochemical contents of greenhouse grown lettuces.

    Science.gov (United States)

    Li, Zheng; Zhao, Xin; Sandhu, Amandeep K; Gu, Liwei

    2010-05-26

    Antioxidants and phytochemicals in vegetables are known to provide health benefits. Strategies that enhance these properties are expected to increase the nutritional values of vegetables. The objective of this research is to assess the effects of exogenous abscisic acid (ABA) on yield, antioxidant capacities, and phytochemical content of lettuces grown in a greenhouse. Red loose leaf lettuce (cv. Galactic) and green loose leaf lettuce (cv. Simpson Elite) were cultivated using a randomized complete block design. Three concentrations of ABA in water [0 (control), 150, 300 ppm] were sprayed on the 30th and 39th days after sowing, and lettuces were harvested on the 46th day. Exogenous ABA significantly decreased yield of green and red lettuces. Total phenolic and total anthocyanin contents in red lettuce treated with ABA were significantly higher than in controls, whereas no significant differences were observed in green lettuce. ABA significantly induced the accumulation of chlorophyll b and total carotenoids in lettuces. The phenolic compounds identified and quantified in red and green lettuces included caffeoyltartaric acid, 5-O-caffeoylquinic acid, dicaffeoyltartaric acid, 3,5-dicaffeoylquinic acid, and quercetin 3-(6''-malonyl)-glucoside. Additionally, cyanidin 3-glucoside, cyanidin 3-(3''-malonoyl)-glucoside, and cyanidin 3-(6''-malonoyl)-glucoside in red lettuces were quantified. No significant effects of ABA on these individual phytochemicals were observed in green lettuces, whereas ABA significantly elevated the content of individual phytochemicals in red lettuces except for 5-O-caffeoylquinic acid. Differences among red lettuces with or without exogenous ABA were visualized on the score plots of principal component analyses. Loading plot indicated that multiple phenolic compounds contributed to the observed differences in red lettuces.

  2. Antagonism between abscisic acid and gibberellins is partially mediated by ascorbic acid during seed germination in rice.

    Science.gov (United States)

    Ye, Nenghui; Zhang, Jianhua

    2012-05-01

    The antagonism between abscisic acid (ABA) and gibberellin (GA) plays a key role in controlling seed germination, but the mechanism of antagonism during this process is not known. In the associated study, we investigated the relationship among ABA, reactive oxygen species (ROS), ascorbic acid (ASC) and GA during rice seed germination. ROS production is reduced by ABA, which hence results in decreasing ASC accumulation during imbibition. GA accumulation was also suppressed by a reduced ROS and ASC level, whereas application of exogenous ASC can partially rescue seed germination from ABA treatment. Further results show that production of ASC, which acts as a substrate in GA biosynthesis, was significantly inhibited by lycorine which thus suppressed the accumulation of GA. Consequently, expression of GA biosynthesis genes was suppressed by the low levels of ROS and ASC in ABA-treated seeds. These studies reveal a new role for ASC in mediating the antagonism between ABA and GA during seed germination in rice.

  3. K-channels inhibited by hydrogen peroxide mediate abscisic acid signaling in Vicia guard cells

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A number of studies show that environmental stress conditions increase abscisic acid (ABA) and hydrogen peroxide (H2O2) levels in plant cells. Despite this central role of ABA in altering stomatal aperture by regulating guard cell ion transport, little is known concerning the relationship between ABA and H2O2 in signal transduction leading to stomatal movement. Epidermal strip bioassay illustrated that ABA-inhibited stomatal opening and ABA-induced stomatal closure were abolished partly by externally added catalase (CAT) or diphenylene iodonium (DPI), which are a H2O2 scavenger and a NADPH oxidase inhibitor respectively. In contrast, internally added CAT or DPI nearly completely or partly reversed ABA-induced closure in half-stoma. Consistent with these results, whole-cell patch-clamp analysis showed that intracellular application of CAT or DPI partly abolished ABA-inhibited inward K+ current across the plasma membrane of guard cells. H2O2 mimicked ABA to inhibit inward K+ current, an effect which was reversed by the addition of ascorbic acid (Vc) in patch clamping micropipettes. These results suggested that H2O2 mediated ABA-induced stomatal movement by targeting inward K+ channels at plasma membrane.

  4. Detection of phytohormones in temperate forest fungi predicts consistent abscisic acid production and a common pathway for cytokinin biosynthesis.

    Science.gov (United States)

    Morrison, Erin N; Knowles, Sarah; Hayward, Allison; Thorn, R Greg; Saville, Barry J; Emery, R J N

    2015-01-01

    The phytohormones, abscisic acid and cytokinin, once were thought to be present uniquely in plants, but increasing evidence suggests that these hormones are present in a wide variety of organisms. Few studies have examined fungi for the presence of these "plant" hormones or addressed whether their levels differ based on the nutrition mode of the fungus. This study examined 20 temperate forest fungi of differing nutritional modes (ectomycorrhizal, wood-rotting, saprotrophic). Abscisic acid and cytokinin were present in all fungi sampled; this indicated that the sampled fungi have the capacity to synthesize these two classes of phytohormones. Of the 27 cytokinins analyzed by HPLC-ESI MS/MS, seven were present in all fungi sampled. This suggested the existence of a common cytokinin metabolic pathway in fungi that does not vary among different nutritional modes. Predictions regarding the source of isopentenyl, cis-zeatin and methylthiol CK production stemming from the tRNA degradation pathway among fungi are discussed.

  5. Protein Geranylgeranyltransferase I Is Involved in Specific Aspects of Abscisic Acid and Auxin Signaling in Arabidopsis1

    Science.gov (United States)

    Johnson, Cynthia D.; Chary, S. Narasimha; Chernoff, Ellen A.; Zeng, Qin; Running, Mark P.; Crowell, Dring N.

    2005-01-01

    Arabidopsis (Arabidopsis thaliana) mutants lacking a functional ERA1 gene, which encodes the β-subunit of protein farnesyltransferase (PFT), exhibit pleiotropic effects that establish roles for protein prenylation in abscisic acid (ABA) signaling and meristem development. Here, we report the effects of T-DNA insertion mutations in the Arabidopsis GGB gene, which encodes the β-subunit of protein geranylgeranyltransferase type I (PGGT I). Stomatal apertures of ggb plants were smaller than those of wild-type plants at all concentrations of ABA tested, suggesting that PGGT I negatively regulates ABA signaling in guard cells. However, germination of ggb seeds in response to ABA was similar to the wild type. Lateral root formation in response to exogenous auxin was increased in ggb seedlings compared to the wild type, but no change in auxin inhibition of primary root growth was observed, suggesting that PGGT I is specifically involved in negative regulation of auxin-induced lateral root initiation. Unlike era1 mutants, ggb mutants exhibited no obvious developmental phenotypes. However, era1 ggb double mutants exhibited more severe developmental phenotypes than era1 mutants and were indistinguishable from plp mutants lacking the shared α-subunit of PFT and PGGT I. Furthermore, overexpression of GGB in transgenic era1 plants partially suppressed the era1 phenotype, suggesting that the relatively weak phenotype of era1 plants is due to partial redundancy between PFT and PGGT I. These results are discussed in the context of Arabidopsis proteins that are putative substrates of PGGT I. PMID:16183844

  6. The plant cuticle is required for osmotic stress regulation of abscisic acid biosynthesis and osmotic stress tolerance in Arabidopsis

    KAUST Repository

    Wang, Zhenyu

    2011-05-01

    Osmotic stress activates the biosynthesis of abscisic acid (ABA). One major step in ABA biosynthesis is the carotenoid cleavage catalyzed by a 9-cis epoxycarotenoid dioxygenase (NCED). To understand the mechanism for osmotic stress activation of ABA biosynthesis, we screened for Arabidopsis thaliana mutants that failed to induce the NCED3 genee xpression in response to osmotic stress treatments. The ced1 (for 9-cis epoxycarotenoid dioxy genase defective 1) mutant isolated in this study showed markedly reduced expression of NCED3 in response to osmotic stress (polyethylene glycol)treatments compared with the wild type. Other ABA biosynthesis genes are also greatly reduced in ced1 under osmotic stress. ced1 mutant plants are very sensitive to even mild osmotic stress. Map-based cloning revealed unexpectedly thatCED1 encodes a putative a/b hydrolase domain-containing protein and is allelic to the BODYGUARD gene that was recently shown to be essential for cuticle biogenesis. Further studies discovered that other cut in biosynthesis mutants are also impaired in osmotic stress induction of ABA biosynthesis genes and are sensitive to osmotic stress. Our work demonstrates that the cuticle functions not merely as a physical barrier to minimize water loss but also mediates osmotic stress signaling and tolerance by regulating ABA biosynthesis and signaling. © 2011 American Society of Plant Biologists. All rights reserved.

  7. Overexpression of AtABCG25 enhances the abscisic acid signal in guard cells and improves plant water use efficiency.

    Science.gov (United States)

    Kuromori, Takashi; Fujita, Miki; Urano, Kaoru; Tanabata, Takanari; Sugimoto, Eriko; Shinozaki, Kazuo

    2016-10-01

    In addition to improving drought tolerance, improvement of water use efficiency is a major challenge in plant physiology. Due to their trade-off relationships, it is generally considered that achieving stress tolerance is incompatible with maintaining stable growth. Abscisic acid (ABA) is a key phytohormone that regulates the balance between intrinsic growth and environmental responses. Previously, we identified AtABCG25 as a cell-membrane ABA transporter that export ABA from the inside to the outside of cells. AtABCG25-overexpressing plants showed a lower transpiration phenotype without any growth retardation. Here, we dissected this useful trait using precise phenotyping approaches. AtABCG25 overexpression stimulated a local ABA response in guard cells. Furthermore, AtABCG25 overexpression enhanced drought tolerance, probably resulting from maintenance of water contents over the common threshold for survival after drought stress treatment. Finally, we observed enhanced water use efficiency by overexpression of AtABCG25, in addition to drought tolerance. These results were consistent with the function of AtABCG25 as an ABA efflux transporter. This unique trait may be generally useful for improving the water use efficiency and drought tolerance of plants.

  8. Comparative Transcriptome Analysis Reveals the Influence of Abscisic Acid on the Metabolism of Pigments, Ascorbic Acid and Folic Acid during Strawberry Fruit Ripening.

    Science.gov (United States)

    Li, Dongdong; Li, Li; Luo, Zisheng; Mou, Wangshu; Mao, Linchun; Ying, Tiejin

    2015-01-01

    A comprehensive investigation of abscisic acid (ABA) biosynthesis and its influence on other important phytochemicals is critical for understanding the versatile roles that ABA plays during strawberry fruit ripening. Using RNA-seq technology, we sampled strawberry fruit in response to ABA or nordihydroguaiaretic acid (NDGA; an ABA biosynthesis blocker) treatment during ripening and assessed the expression changes of genes involved in the metabolism of pigments, ascorbic acid (AsA) and folic acid in the receptacles. The transcriptome analysis identified a lot of genes differentially expressed in response to ABA or NDGA treatment. In particular, genes in the anthocyanin biosynthesis pathway were actively regulated by ABA, with the exception of the gene encoding cinnamate 4-hydroxylase. Chlorophyll degradation was accelerated by ABA mainly owing to the higher expression of gene encoding pheide a oxygenase. The decrease of β-carotene content was accelerated by ABA treatment and delayed by NDGA. A high negative correlation rate was found between ABA and β-carotene content, indicating the importance of the requirement for ABA synthesis during fruit ripening. In addition, evaluation on the folate biosynthetic pathway indicate that ABA might have minor function in this nutrient's biosynthesis process, however, it might be involved in its homeostasis. Surprisingly, though AsA content accumulated during fruit ripening, expressions of genes involved in its biosynthesis in the receptacles were significantly lower in ABA-treated fruits. This transcriptome analysis expands our understanding of ABA's role in phytochemical metabolism during strawberry fruit ripening and the regulatory mechanisms of ABA on these pathways were discussed. Our study provides a wealth of genetic information in the metabolism pathways and may be helpful for molecular manipulation in the future.

  9. Comparative Transcriptome Analysis Reveals the Influence of Abscisic Acid on the Metabolism of Pigments, Ascorbic Acid and Folic Acid during Strawberry Fruit Ripening.

    Directory of Open Access Journals (Sweden)

    Dongdong Li

    Full Text Available A comprehensive investigation of abscisic acid (ABA biosynthesis and its influence on other important phytochemicals is critical for understanding the versatile roles that ABA plays during strawberry fruit ripening. Using RNA-seq technology, we sampled strawberry fruit in response to ABA or nordihydroguaiaretic acid (NDGA; an ABA biosynthesis blocker treatment during ripening and assessed the expression changes of genes involved in the metabolism of pigments, ascorbic acid (AsA and folic acid in the receptacles. The transcriptome analysis identified a lot of genes differentially expressed in response to ABA or NDGA treatment. In particular, genes in the anthocyanin biosynthesis pathway were actively regulated by ABA, with the exception of the gene encoding cinnamate 4-hydroxylase. Chlorophyll degradation was accelerated by ABA mainly owing to the higher expression of gene encoding pheide a oxygenase. The decrease of β-carotene content was accelerated by ABA treatment and delayed by NDGA. A high negative correlation rate was found between ABA and β-carotene content, indicating the importance of the requirement for ABA synthesis during fruit ripening. In addition, evaluation on the folate biosynthetic pathway indicate that ABA might have minor function in this nutrient's biosynthesis process, however, it might be involved in its homeostasis. Surprisingly, though AsA content accumulated during fruit ripening, expressions of genes involved in its biosynthesis in the receptacles were significantly lower in ABA-treated fruits. This transcriptome analysis expands our understanding of ABA's role in phytochemical metabolism during strawberry fruit ripening and the regulatory mechanisms of ABA on these pathways were discussed. Our study provides a wealth of genetic information in the metabolism pathways and may be helpful for molecular manipulation in the future.

  10. Effects of abscisic acid, gibberellin, ethylene and their interactions on production of phenolic acids in salvia miltiorrhiza bunge hairy roots.

    Science.gov (United States)

    Liang, Zongsuo; Ma, Yini; Xu, Tao; Cui, Beimi; Liu, Yan; Guo, Zhixin; Yang, Dongfeng

    2013-01-01

    Salvia miltiorrhiza is one of the most important traditional Chinese medicinal plants because of its excellent performance in treating coronary heart disease. Phenolic acids mainly including caffeic acid, rosmarinic acid and salvianolic acid B are a group of active ingredients in S. miltiorrhiza. Abscisic acid (ABA), gibberellin (GA) and ethylene are three important phytohormones. In this study, effects of the three phytohormones and their interactions on phenolic production in S. miltiorrhiza hairy roots were investigated. The results showed that ABA, GA and ethylene were all effective to induce production of phenolic acids and increase activities of PAL and TAT in S. miltiorrhiza hairy roots. Effects of phytohormones were reversed by their biosynthetic inhibitors. Antagonistic actions between the three phytohormones played important roles in the biosynthesis of phenolic acids. GA signaling is necessary for ABA and ethylene-induced phenolic production. Yet, ABA and ethylene signaling is probably not necessary for GA3-induced phenolic production. The complex interactions of phytohormones help us reveal regulation mechanism of secondary metabolism and scale-up production of active ingredients in plants.

  11. Effects of abscisic acid, gibberellin, ethylene and their interactions on production of phenolic acids in salvia miltiorrhiza bunge hairy roots.

    Directory of Open Access Journals (Sweden)

    Zongsuo Liang

    Full Text Available Salvia miltiorrhiza is one of the most important traditional Chinese medicinal plants because of its excellent performance in treating coronary heart disease. Phenolic acids mainly including caffeic acid, rosmarinic acid and salvianolic acid B are a group of active ingredients in S. miltiorrhiza. Abscisic acid (ABA, gibberellin (GA and ethylene are three important phytohormones. In this study, effects of the three phytohormones and their interactions on phenolic production in S. miltiorrhiza hairy roots were investigated. The results showed that ABA, GA and ethylene were all effective to induce production of phenolic acids and increase activities of PAL and TAT in S. miltiorrhiza hairy roots. Effects of phytohormones were reversed by their biosynthetic inhibitors. Antagonistic actions between the three phytohormones played important roles in the biosynthesis of phenolic acids. GA signaling is necessary for ABA and ethylene-induced phenolic production. Yet, ABA and ethylene signaling is probably not necessary for GA3-induced phenolic production. The complex interactions of phytohormones help us reveal regulation mechanism of secondary metabolism and scale-up production of active ingredients in plants.

  12. Nucleotide sequence and spatial expression pattern of a drought- and abscisic Acid-induced gene of tomato.

    Science.gov (United States)

    Plant, A L; Cohen, A; Moses, M S; Bray, E A

    1991-11-01

    The nucleotide sequence of le16, a tomato (Lycopersicon esculentum Mill.) gene induced by drought stress and regulated by abscisic acid specifically in aerial vegetative tissue, is presented. The single open reading frame contained within the gene has the capacity to encode a polypeptide of 12.7 kilodaltons and is interrupted by a small intron. The predicted polypeptide is rich in leucine, glycine, and alanine and has an isoelectric point of 8.7. The amino terminus is hydrophobic and characteristic of signal sequences that target polypeptides for export from the cytoplasm. There is homology (47.2% identity) between the amino terminus of the LE 16 polypeptide and the corresponding amino terminal domain of the maize phospholipid transfer protein. le16 was expressed in drought-stressed leaf, petiole, and stem tissue and to a much lower extent in the pericarp of mature green tomato fruit and developing seeds. No expression was detected in the pericarp of red fruit or in drought-stressed roots. Expression of le16 was also induced in leaf tissue by a variety of other abiotic stresses including polyethylene glycol-mediated water deficit, salinity, cold stress, and heat stress. None of these stresses or direct applications of abscisic acid induced the expression of le16 in the roots of the same plants. The unique expression characteristics of this gene indicates that novel regulatory mechanisms, in addition to endogenous abscisic acid, are involved in controlling gene expression.

  13. Abscisic acid accumulation in spinach leaf slices in the presence of penetrating and nonpenetrating solutes

    Energy Technology Data Exchange (ETDEWEB)

    Creelman, R.A.; Zeevaart, J.A.D.

    1985-01-01

    Abscisic acid (ABA) accumulated in detached, wilted leaves of spinach (Spinacia oleracea L. cv Savoy Hybrid 612) and reached a maximum level within 3 to 4 hours. The increase in ABA over that found in detached turgid leaves was approximately 10-fold. The effects of water stress could be mimicked by the use of thin slices of spinach leaves incubated in the presence of 0.6 molar mannitol, a compound which causes plasmolysis (loss of turgor). When spinach leaf slices were incubated with ethylene glycol, a compound which rapidly penetrates the cell membrane causing a decrease in the osmotic potential of the tissue and only transient loss of turgor, no ABA accumulated. Spinach leaf slices incubated in both ethylene glycol and mannitol had ABA levels similar to those found when slices were incubated with mannitol alone. Increases similar to those found with mannitol also occurred when Aquacide III, a highly purified form of polyethylene glycol, was used. When spinach leaf slices were incubated with solutes which are supposed to disturb membrane integrity no increase in ABA was observed. These data indicate that, with respect to the accumulation of ABA, mannitol caused a physical stress rather than a chemical stress.

  14. Role of Soybean GmbZIP132 under Abscisic Acid and Salt Stresses

    Institute of Scientific and Technical Information of China (English)

    Yong Liao; Jin-Song Zhang; Shou-Yi Chen; Wan-Ke Zhang

    2008-01-01

    Plant basic-leucina zipper (bZIP) transcription factors play important roles in many biological processes. In the present study, a bZIP gene, GmbZIP132, was cloned from soybean and its biological function under abiotic stresses was studied. The transcription of GmbZIP132 was Induced by drought and high salt treatments. Among all of the organs analyzed, its expression was the highest in cotyUedon and stems. GmbZIP132 could weakly bind to the GCN4-1ika motif (GLM) (5'-GTGAGTCAT-3') In yeast one-hybrid assay. Compared with wild-type (WT) Arabidopsis plants, transgenic plants overexpressing GmbZIP132 showed reduced abscisic acid sensitivity and increased water loss rate. At the stage of germination, transgenic plants were more tolerant to salt treatment than wild-type plants. The expression of some abiotic stress-related genes, such as rd29B, DREB2A, and PSCS, were upregulatsd in the transgenic plants. These results indicated that GmbZIP132 was an abiotic atress-related gene, and its overexpression could increase the salt tolerance of transgenic Arabidopsis plants dudng germination, yet no significant difference of tolerance to abiotic stresses was found between transgenic and wild type plants at the seedling stage.

  15. Proanthocyanidins Inhibit Seed Germination by Maintaining a High Level of Abscisic Acid in Arabidopsis thaliana

    Institute of Scientific and Technical Information of China (English)

    Liguo Jia; Jianhua Zhang; Qiuyu Wu; Nenghui Ye; Rui Liu; Lu Shi; Weifeng Xu; Hui Zhi; A. N. M. Rubaiyath Bin Rahman; Yiji Xia

    2012-01-01

    Proanthocyanidins (PAs) are the main products of the flavonoid biosynthetic pathway in seeds,but their biological function during seed germination is still unclear.We observed that seed germination is delayed with the increase of exogenous PA concentration in Arabidopsis.A similar inhibitory effect occurred in peeled Brassica napus seeds,which was observed by measuring radicle elongation.Using abscisic acid (ABA),a biosynthetic and metabolic inhibitor,and gene expression analysis by real-time polymerase chain reaction,we found that the inhibitory effect of PAs on seed germination is due to their promotion of ABA via de novo biogenesis,rather than by any inhibition of its degradation.Consistent with the relationship between PA content and ABA accumulation in seeds,PA-deficient mutants maintain a lower level of ABA compared with wild-types during germination.Our data suggest that PA distribution in the seed coat can act as a doorkeeper to seed germination.PA regulation of seed germination is mediated by the ABA signaling pathway.

  16. The Effect of Abscisic Acid on the Freezing Tolerance of Callus Cultures of Lotus corniculatus L.

    Science.gov (United States)

    Keith, C N; McKersie, B D

    1986-03-01

    The effects of growth temperature (2 degrees C and 24 degrees C), abscisic acid (ABA) concentration, duration of exposure to ABA, and light were assessed for their ability to induce acclimation to freezing temperatures in callus cultures of Lotus corniculatus L. cv Leo, a perennial forage legume. The maximal expression of freezing tolerance was achieved on B(5) media containing 10(-5) molar ABA, at 24 degrees C for 7 or 14 days. Under these culture conditions, the freezing tolerance of the callus approximated that observed in field grown plants. In contrast, low temperatures (2 degrees C) induced only a limited degree of freezing tolerance in these cultures. Viability was assessed by tetrazolium reduction and by regrowth of the callus. The two assays often differed in their estimates of absolute freezing tolerance. Regression analysis of the temperature profile suggested that there may be two or more distinct populations of cells differing in freezing tolerance, which may have contributed to the variability between viability assays.

  17. Color of berry and juice of 'Isabel' grape treated with abscisic acid in different ripening stages

    Directory of Open Access Journals (Sweden)

    Lilian Yukari Yamamoto

    2015-12-01

    Full Text Available Abstract : The objective of this work was to evaluate the effect of (S-cis-abscisic acid (S-ABA application at different ripening stages, in increasing phenolic compounds and color of berry and juice of 'Isabel' grape (Vitis labrusca. The evaluated treatments were: control, without S-ABA application; 400 mg L-1S-ABA applied 7 days before veraison (DBV + 400 mg L-1S-ABA at 35 days after first application (DAFA; 400 mg L-1S-ABA applied at veraison (V + 400 mg L-1S-ABA at 35 DAFA; and 400 mg L-1S-ABA applied 7 days after veraison (DAV + 400 mg L-1S-ABA at 35 DAFA. There was no difference among treatments regarding the physical characteristics of berries and clusters, as well as total polyphenols in berry and juice. However, there was an increase in total anthocyanins in berry and juice with S-ABA application. Colorimetric variables indicated the increase in color of berry treated with S-ABA. Juices produced from grapes treated with S-ABA were more appreciated by tasters. The treatments with 400 mg L-1S-ABA applied 7 days before, during, or 7 days after veraison, combined with an additional application 35 days after the first one, increment total anthocyanin concentration and color of berry and juice of 'Isabel' grape, with better juice acceptance, without affecting total polyphenol concentration.

  18. ABI4 mediates antagonistic effects of abscisic acid and gibberellins at transcript and protein levels.

    Science.gov (United States)

    Shu, Kai; Chen, Qian; Wu, Yaorong; Liu, Ruijun; Zhang, Huawei; Wang, Pengfei; Li, Yanli; Wang, Shengfu; Tang, Sanyuan; Liu, Chunyan; Yang, Wenyu; Cao, Xiaofeng; Serino, Giovanna; Xie, Qi

    2016-02-01

    Abscisic acid (ABA) and gibberellins (GAs) are plant hormones which antagonistically mediate numerous physiological processes, and their optimal balance is essential for normal plant development. However, the molecular mechanism underlying ABA and GA antagonism still needs to be determined. Here, we report that ABA-INSENSITIVE 4 (ABI4) is a central factor in GA/ABA homeostasis and antagonism in post-germination stages. ABI4 overexpression in Arabidopsis (OE-ABI4) leads to developmental defects including a decrease in plant height and poor seed production. The transcription of a key ABA biosynthetic gene, NCED6, and of a key GA catabolic gene, GA2ox7, is significantly enhanced by ABI4 overexpression. ABI4 activates NCED6 and GA2ox7 transcription by directly binding to the promoters, and genetic analysis revealed that mutation in these two genes partially rescues the dwarf phenotype of ABI4 overexpressing plants. Consistently, ABI4 overexpressing seedlings have a lower GA/ABA ratio than the wild type. We further show that ABA induces GA2ox7 transcription while GA represses NCED6 expression in an ABI4-dependent manner; and that ABA stabilizes the ABI4 protein whereas GA promotes its degradation. Taken together, these results suggest that ABA and GA antagonize each other by oppositely acting on ABI4 transcript and protein levels.

  19. Influence of abscisic acid and sucrose on somatic embryogenesis in Cactus Copiapoa tenuissima Ritt. forma mostruosa.

    Science.gov (United States)

    Lema-Rumińska, J; Goncerzewicz, K; Gabriel, M

    2013-01-01

    Having produced the embryos of cactus Copiapoa tenuissima Ritt. forma monstruosa at the globular stage and callus, we investigated the effect of abscisic acid (ABA) in the following concentrations: 0, 0.1, 1, 10, and 100  μ M on successive stages of direct (DSE) and indirect somatic embryogenesis (ISE). In the indirect somatic embryogenesis process we also investigated a combined effect of ABA (0, 0.1, 1  μ M) and sucrose (1, 3, 5%). The results showed that a low concentration of ABA (0-1  μ M) stimulates the elongation of embryos at the globular stage and the number of correct embryos in direct somatic embryogenesis, while a high ABA concentration (10-100  μ M) results in growth inhibition and turgor pressure loss of somatic embryos. The indirect somatic embryogenesis study in this cactus suggests that lower ABA concentrations enhance the increase in calli fresh weight, while a high concentration of 10  μ M ABA or more changes calli color and decreases its proliferation rate. However, in the case of indirect somatic embryogenesis, ABA had no effect on the number of somatic embryos and their maturation. Nevertheless, we found a positive effect of sucrose concentration for both the number of somatic embryos and the increase in calli fresh weight.

  20. Drought-Induced Increases in Abscisic Acid Levels in the Root Apex of Sunflower 1

    Science.gov (United States)

    Robertson, J. Mason; Pharis, Richard P.; Huang, Yan Y.; Reid, David M.; Yeung, Edward C.

    1985-01-01

    Abscisic acid (ABA) levels in 3-mm apical root segments of slowly droughted sunflower plants (Helianthus annuus L. cv Russian Giant) were analyzed as the methyl ester by selected ion monitoring gas chromatography-mass spectrometry using characteristic ions. An internal standard, hexadeuterated ABA (d6ABA) was used for quantitative analysis. Sunflower seedlings, grown in aeroponic chambers, were slowly droughted over a 7-day period. Drought stress increased ABA levels in the root tips at 24, 72, and 168 hour sample times. Control plants had 57 to 106 nanograms per gram ABA dry weight in the root tips (leaf water potential, −0.35 to −0.42 megapascals). The greatest increase in ABA, about 20-fold, was found after 72 hours of drought (leaf water potential, −1.34 to −1.47 megapascals). Levels of ABA also increased (about 7− to 54-fold) in 3-mm apical root segments which were excised and then allowed to dessicate for 1 hour at room temperature. PMID:16664535

  1. Reactive oxygen species, abscisic acid and ethylene interact to regulate sunflower seed germination.

    Science.gov (United States)

    El-Maarouf-Bouteau, Hayat; Sajjad, Yasar; Bazin, Jérémie; Langlade, Nicolas; Cristescu, Simona M; Balzergue, Sandrine; Baudouin, Emmanuel; Bailly, Christophe

    2015-02-01

    Sunflower (Helianthus annuus L.) seed dormancy is regulated by reactive oxygen species (ROS) and can be alleviated by incubating dormant embryos in the presence of methylviologen (MV), a ROS-generating compound. Ethylene alleviates sunflower seed dormancy whereas abscisic acid (ABA) represses germination. The purposes of this study were to identify the molecular basis of ROS effect on seed germination and to investigate their possible relationship with hormone signalling pathways. Ethylene treatment provoked ROS generation in embryonic axis whereas ABA had no effect on their production. The beneficial effect of ethylene on germination was lowered in the presence of antioxidant compounds, and MV suppressed the inhibitory effect of ABA. MV treatment did not alter significantly ethylene nor ABA production during seed imbibition. Microarray analysis showed that MV treatment triggered differential expression of 120 probe sets (59 more abundant and 61 less abundant genes), and most of the identified transcripts were related to cell signalling components. Many transcripts less represented in MV-treated seeds were involved in ABA signalling, thus suggesting an interaction between ROS and ABA signalling pathways at the transcriptional level. Altogether, these results shed new light on the crosstalk between ROS and plant hormones in seed germination.

  2. Overexpression of OsWRKY72 gene interferes in the abscisic acid signal and auxin transport pathway of Arabidopsis

    Indian Academy of Sciences (India)

    Song Yu; Chen Ligang; Zhang Liping; Yu Diqiu

    2010-09-01

    Through activating specific transcriptional programmes, plants can launch resistance mechanisms to stressful environments and acquire a new equilibrium between development and defence. To screen the rice WRKY transcription factor which functions in abiotic stress tolerance and modulates the abscisic acid (ABA) response, we generated a whole array of 35S-OsWRKY transgenic Arabidopsis. In this study, we report that 35S-OsWRKY72 transgenic Arabidopsis, whose seed germination was retarded under normal conditions, emerged more sensitive to mannitol, NaCl, ABA stresses and sugar starvation than vector plants. Meanwhile, 35S-OsWRKY72 transgenic Arabidopsis displayed early flowering, reduced apical dominance, lost high temperature-induced hypocotyl elongation response, and enhanced gravitropism response, which were similar to the auxin-related gene mutants aux1, axr1 and bud1. Further, semi-quantitative RT-PCR showed that the expression patterns of three auxin-related genes AUX1, AXR1 and BUD1 were significantly altered in rosette leaves and inflorescences of 35S-OsWRKY72 plants compared with control Arabidopsis, and two ABA-related genes ABA2 and ABI4 were induced in 35S-OsWRKY72 seedlings. In addition, northern blot analysis indicated that, in rice, OsWRKY72 was inducible by polyethylene glycol (PEG), NaCl, naphthalene acetic acid (NAA), ABA and 42°C, similar to its orthologue AtWRKY75 in Arabidopsis, implying that these two WRKY genes might be required for multiple physiological processes in their plants. Together, these results suggest that OsWRKY72 interferes in the signal cross-talk between the ABA signal and auxin transport pathway in transgenic Arabidopsis.

  3. Genetic analyses of interactions among gibberellin, abscisic acid, and brassinosteroids in the control of flowering time in Arabidopsis thaliana.

    Directory of Open Access Journals (Sweden)

    Malgorzata A Domagalska

    Full Text Available BACKGROUND: Genetic interactions between phytohormones in the control of flowering time in Arabidopsis thaliana have not been extensively studied. Three phytohormones have been individually connected to the floral-timing program. The inductive function of gibberellins (GAs is the most documented. Abscisic acid (ABA has been demonstrated to delay flowering. Finally, the promotive role of brassinosteroids (BRs has been established. It has been reported that for many physiological processes, hormone pathways interact to ensure an appropriate biological response. METHODOLOGY: We tested possible genetic interactions between GA-, ABA-, and BR-dependent pathways in the control of the transition to flowering. For this, single and double mutants deficient in the biosynthesis of GAs, ABA, and BRs were used to assess the effect of hormone deficiency on the timing of floral transition. Also, plants that over-express genes encoding rate-limiting enzymes in each biosynthetic pathway were generated and the flowering time of these lines was investigated. CONCLUSIONS: Loss-of-function studies revealed a complex relationship between GAs and ABA, and between ABA and BRs, and suggested a cross-regulatory relation between GAs to BRs. Gain-of-function studies revealed that GAs were clearly limiting in their sufficiency of action, whereas increases in BRs and ABA led to a more modest phenotypic effect on floral timing. We conclude from our genetic tests that the effects of GA, ABA, and BR on timing of floral induction are only in partially coordinated action.

  4. Abscisic acid controls embryo growth potential and endosperm cap weakening during coffee (Coffea arabica cv. Rubi) seed germination.

    Science.gov (United States)

    da Silva, E A Amaral; Toorop, Peter E; van Aelst, Adriaan C; Hilhorst, Henk W M

    2004-12-01

    The mechanism and regulation of coffee seed germination were studied in Coffea arabica L. cv. Rubi. The coffee embryo grew inside the endosperm prior to radicle protrusion and abscisic acid (ABA) inhibited the increase in its pressure potential. There were two steps of endosperm cap weakening. An increase in cellulase activity coincided with the first step and an increase in endo-beta-mannanase (EBM) activity with the second step. ABA inhibited the second step of endosperm cap weakening, presumably by inhibiting the activities of at least two EBM isoforms and/or, indirectly, by inhibiting the pressure force of the radicle. The increase in the activities of EBM and cellulase coincided with the decrease in the force required to puncture the endosperm and with the appearance of porosity in the cell walls as observed by low-temperature scanning electronic microscopy. Tissue printing showed that EBM activity was spatially regulated in the endosperm. Activity was initiated in the endosperm cap whereas later during germination it could also be detected in the remainder of the endosperm. Tissue printing revealed that ABA inhibited most of the EBM activity in the endosperm cap, but not in the remainder of the endosperm. ABA did not inhibit cellulase activity. There was a transient rise in ABA content in the embryo during imbibition, which was likely to be responsible for slow germination, suggesting that endogenous ABA also may control embryo growth potential and the second step of endosperm cap weakening during coffee seed germination.

  5. Integrin-like Protein Is Involved in the Osmotic Stress-induced Abscisic Acid Biosynthesis in Arabidopsis thaliana

    Institute of Scientific and Technical Information of China (English)

    Bing Lü; Feng Chen; Zhong-Hua Gong; Hong Xie; Jian-Sheng Liang

    2007-01-01

    We studied the perception of plant cells to osmotic stress that leads to the accumulation of abscisic acid (ABA) in stressed Arabidopsis thaliana L. cells. A significant difference was found between protoplasts and cells in terms of their responses to osmotic stress and ABA biosynthesis, implying that cell wall and/or cell wall-plasma membrane interaction are essential in identifying osmotic stress. Western blotting and immunofluorescence localization experiments, using polyclonal antibody against human integrin β1, revealed the existence of a protein similar to the integrin protein of animals in the suspension-cultured cells located in the plasma membrane fraction.Treatment with a synthetic pentapeptide, Gly-Arg-Gly-Asp-Ser (GRGDS), which contains an RGD domain and interacts specifically with integrin protein and thus blocks the cell wall-plasma membrane interaction, significantly inhibited osmotic stress-induced ABA biosynthesis in cells, but not in protoplasts. These results demonstrate that cell wall and/or cell wall-plasma membrane interaction mediated by integrin-like proteins played important roles in osmotic stress-induced ABA biosynthesis in Arabidopsis thaliana.

  6. Eucalyptus ESTs involved in the production of 9-cis epoxycarotenoid dioxygenase, a regulatory enzyme of abscisic acid production

    Directory of Open Access Journals (Sweden)

    Iraê A. Guerrini

    2005-01-01

    Full Text Available Abscisic acid (ABA regulates stress responses in plants, and genomic tools can help us to understand the mechanisms involved in that process. FAPESP, a Brazilian research foundation, in association with four private forestry companies, has established the FORESTs database (https://forests.esalq.usp.br. A search was carried out in the Eucalyptus expressed sequence tag database to find ESTs involved with 9-cis epoxycarotenoid dioxygenase (NCED, the regulatory enzyme for ABA biosynthesis, using the basic local BLAST alignment tool. We found four clusters (EGEZLV2206B11.g, EGJMWD2252H08.g, EGBFRT3107F10.g, and EGEQFB1200H10.g, which represent similar sequences of the gene that produces NCED. Data showed that the EGBFRT3107F10.g cluster was similar to the maize (Zea mays NCED enzyme, while EGEZLV2206B11.g and EGJMWD2252H08.g clusters were similar to the avocado (Persea americana NCED enzyme. All Eucalyptus clusters were expressed in several tissues, especially in flower buds, where ABA has a special participation during the floral development process.

  7. The parasitic plant Cuscuta australis is highly insensitive to abscisic acid-induced suppression of hypocotyl elongation and seed germination.

    Directory of Open Access Journals (Sweden)

    Juan Li

    Full Text Available Around 1% of angiosperms are parasitic plants. Their growth and development solely or partly depend on host plants from which they extract water, nutrients, and other molecules using a parasitic plant-specific organ, the haustorium. Strong depletion of nutrients can result in serious growth retardation and in some cases, death of the hosts. The genus Cuscuta (dodder comprises about 200 holoparasitic species occurring on all continents. Their seedlings have no roots and cotyledons but are only string-like hypocotyls. When they contact suitable host plants, haustoria are formed and thereafter seedlings rapidly develop into vigorously growing branches without roots and leaves. This highly specialized lifestyle suggests that Cuscuta plants likely have unique physiology in development and stress responses. Using germination and seedling growth assays, we show that C. australis seeds and seedlings are highly insensitive to abscisic acid (ABA. Transcriptome analysis and protein sequence alignment with Arabidopsis, tomato, and rice homologs revealed that C. australis most likely consists of only four functional ABA receptors. Given that Cuscuta plants are no longer severely challenged by drought stress, we hypothesize that the ABA-mediated drought resistance pathway in Cuscuta spp. might have had degenerated over time during evolution.

  8. Genetic analyses of the interaction between abscisic acid and gibberellins in the control of leaf development in Arabidopsis thaliana.

    Science.gov (United States)

    Chiang, Ming-Hau; Shen, Hwei-Ling; Cheng, Wan-Hsing

    2015-07-01

    Although abscisic acid (ABA) and gibberellins (GAs) play pivotal roles in many physiological processes in plants, their interaction in the control of leaf growth remains elusive. In this study, genetic analyses of ABA and GA interplay in leaf growth were performed in Arabidopsis thaliana. The results indicate that for the ABA and GA interaction, leaf growth of both the aba2/ga20ox1 and aba2/GA20ox1 plants, which were derived from the crosses of aba2×ga20ox1 and aba2×GA20ox1 overexpressor, respectively, exhibits partially additive effects but is similar to the aba2 mutant. Consistently, the transcriptome analysis suggests that a substantial proportion (45-65%) of the gene expression profile of aba2/ga20ox1 and aba2/GA20ox1 plants overlap and share a pattern similar to the aba2 mutant. Thus, these data suggest that ABA deficiency dominates leaf growth regardless of GA levels. Moreover, the gene ontology (GO) analysis indicates gene enrichment in the categories of hormone response, developmental and metabolic processes, and cell wall organization in these three genotypes. Leaf developmental genes are also involved in the ABA-GA interaction. Collectively, these data support that the genetic relationship of ABA and GA interaction involves multiple coordinated pathways rather than a simple linear pathway for the regulation of leaf growth.

  9. Effects of abscisic acid and xanthoxin on elongation and gravitropism in primary roots of Zea mays

    Science.gov (United States)

    Lee, J. S.; Hasenstein, K. H.; Mulkey, T. J.; Yang, R. L.; Evans, M. L.

    1990-01-01

    We examined the involvement of abscisic acid (ABA) and xanthoxin (Xan) in maize root gravitropism by (1) testing the ability of ABA to allow positive gravitropism in dark-grown seedlings of the maize cultivar LG11, a cultivar known to require light for positive gravitropism of the primary root, (2) comparing curvature in roots in which half of the cap had been excised and replaced with agar containing either ABA or indole-3-acetic acid (IAA), (3) measuring gravitropism in roots of seedlings submerged in oxygenated solutions of ABA or IAA and (4) testing the effect of Xan on root elongation. Using a variety of methods of applying ABA to the root, we found that ABA did not cause horizontally-oriented primary roots of dark-grown seedlings to become positively gravitropic. Replacing half of the root cap of vertically oriented roots with an agar block containing ABA had little or no effect on curvature relative to that of controls in which the half cap was replaced by a plain agar block. Replacement of the removed half cap with IAA either canceled or reversed the curvature displayed by controls. When light-grown seedlings were submerged in ABA they responded strongly to gravistimulation while those in IAA did not. Xan (up to 0.1 mM) did not affect root elongation. The results indicate that ABA is not a likely mediator of root gravitropism and that the putative ABA precursor, Xan, lacks the appropriate growth-inhibiting properties to serve as a mediator of root gravitropism.

  10. Onset of herbivore-induced resistance in systemic tissue primed for jasmonate-dependent defenses is activated by abscisic acid.

    Science.gov (United States)

    Vos, Irene A; Verhage, Adriaan; Schuurink, Robert C; Watt, Lewis G; Pieterse, Corné M J; Van Wees, Saskia C M

    2013-01-01

    In Arabidopsis, the MYC2 transcription factor on the one hand and the AP2/ERF transcription factors ORA59 and ERF1 on the other hand regulate distinct branches of the jasmonic acid (JA) signaling pathway in an antagonistic fashion, co-regulated by abscisic acid (ABA) and ethylene, respectively. Feeding by larvae of the specialist herbivorous insect Pieris rapae (small cabbage white butterfly) results in activation of the MYC-branch and concomitant suppression of the ERF-branch in insect-damaged leaves. Here we investigated differential JA signaling activation in undamaged systemic leaves of P. rapae-infested plants. We found that the MYC2 transcription factor gene was induced both in the local insect-damaged leaves and the systemic undamaged leaves of P. rapae-infested Arabidopsis plants. However, in contrast to the insect-damaged leaves, the undamaged tissue did not show activation of the MYC-branch marker gene VSP1. Comparison of the hormone signal signature revealed that the levels of JA and (+)-7-iso-jasmonoyl-L-isoleucine raised to similar extents in locally damaged and systemically undamaged leaves, but the production of ABA and the JA precursor 12-oxo-phytodienoic acid was enhanced only in the local herbivore-damaged leaves, and not in the distal undamaged leaves. Challenge of undamaged leaves of pre-infested plants with either P. rapae larvae or exogenously applied ABA led to potentiated expression levels of MYC2 and VSP1, with the latter reaching extremely high expression levels. Moreover, P. rapae-induced resistance, as measured by reduction of caterpillar growth on pre-infested plants, was blocked in the ABA biosynthesis mutant aba2-1, that was also impaired in P. rapae-induced expression of VSP1. Together, these results suggest that ABA is a crucial regulator of herbivore-induced resistance by activating primed JA-regulated defense responses upon secondary herbivore attack in Arabidopsis.

  11. The Arabidopsis MYB96 Transcription Factor Is a Positive Regulator of ABSCISIC ACID-INSENSITIVE4 in the Control of Seed Germination.

    Science.gov (United States)

    Lee, Kyounghee; Lee, Hong Gil; Yoon, Seongmun; Kim, Hyun Uk; Seo, Pil Joon

    2015-06-01

    Seed germination is a key developmental transition that initiates the plant life cycle. The timing of germination is determined by the coordinated action of two phytohormones, gibberellin and abscisic acid (ABA). In particular, ABA plays a key role in integrating environmental information and inhibiting the germination process. The utilization of embryonic lipid reserves contributes to seed germination by acting as an energy source, and ABA suppresses lipid degradation to modulate the germination process. Here, we report that the ABA-responsive R2R3-type MYB transcription factor MYB96, which is highly expressed in embryo, regulates seed germination by controlling the expression of abscisic acid-insensitive4 (ABI4) in Arabidopsis (Arabidopsis thaliana). In the presence of ABA, germination was accelerated in MYB96-deficient myb96-1 seeds, whereas the process was significantly delayed in MYB96-overexpressing activation-tagging myb96-ox seeds. Consistently, myb96-1 seeds degraded a larger extent of lipid reserves even in the presence of ABA, while reduced lipid mobilization was observed in myb96-ox seeds. MYB96 directly regulates ABI4, which acts as a repressor of lipid breakdown, to define its spatial and temporal expression. Genetic analysis further demonstrated that ABI4 is epistatic to MYB96 in the control of seed germination. Taken together, the MYB96-ABI4 module regulates lipid mobilization specifically in the embryo to ensure proper seed germination under suboptimal conditions.

  12. Arabidopsis glutamate receptor homolog3.5 modulates cytosolic Ca2+ level to counteract effect of abscisic acid in seed germination.

    Science.gov (United States)

    Kong, Dongdong; Ju, Chuanli; Parihar, Aisha; Kim, So; Cho, Daeshik; Kwak, June M

    2015-04-01

    Seed germination is a critical step in a plant's life cycle that allows successful propagation and is therefore strictly controlled by endogenous and environmental signals. However, the molecular mechanisms underlying germination control remain elusive. Here, we report that the Arabidopsis (Arabidopsis thaliana) glutamate receptor homolog3.5 (AtGLR3.5) is predominantly expressed in germinating seeds and increases cytosolic Ca2+ concentration that counteracts the effect of abscisic acid (ABA) to promote germination. Repression of AtGLR3.5 impairs cytosolic Ca2+ concentration elevation, significantly delays germination, and enhances ABA sensitivity in seeds, whereas overexpression of AtGLR3.5 results in earlier germination and reduced seed sensitivity to ABA. Furthermore, we show that Ca2+ suppresses the expression of ABSCISIC ACID INSENSITIVE4 (ABI4), a key transcription factor involved in ABA response in seeds, and that ABI4 plays a fundamental role in modulation of Ca2+-dependent germination. Taken together, our results provide molecular genetic evidence that AtGLR3.5-mediated Ca2+ influx stimulates seed germination by antagonizing the inhibitory effects of ABA through suppression of ABI4. These findings establish, to our knowledge, a new and pivotal role of the plant glutamate receptor homolog and Ca2+ signaling in germination control and uncover the orchestrated modulation of the AtGLR3.5-mediated Ca2+ signal and ABA signaling via ABI4 to fine-tune the crucial developmental process, germination, in Arabidopsis.

  13. Alleviation of Drought Stress by Hydrogen Sulfide Is Partially Related to the Abscisic Acid Signaling Pathway in Wheat

    Science.gov (United States)

    Wang, Chenyang; Qin, Haixia; Han, Qiaoxia; Hou, Junfeng; Lu, Hongfang; Xie, Yingxin; Guo, Tiancai

    2016-01-01

    Little information is available describing the effects of exogenous H2S on the ABA pathway in the acquisition of drought tolerance in wheat. In this study, we investigated the physiological parameters, the transcription levels of several genes involved in the abscisic acid (ABA) metabolism pathway, and the ABA and H2S contents in wheat leaves and roots under drought stress in response to exogenous NaHS treatment. The results showed that pretreatment with NaHS significantly increased plant height and the leaf relative water content of seedlings under drought stress. Compared with drought stress treatment alone, H2S application increased antioxidant enzyme activities and reduced MDA and H2O2 contents in both leaves and roots. NaHS pretreatment increased the expression levels of ABA biosynthesis and ABA reactivation genes in leaves; whereas the expression levels of ABA biosynthesis and ABA catabolism genes were up-regulated in roots. These results indicated that ABA participates in drought tolerance induced by exogenous H2S, and that the responses in leaves and roots are different. The transcription levels of genes encoding ABA receptors were up-regulated in response to NaHS pretreatment under drought conditions in both leaves and roots. Correspondingly, the H2S contents in leaves and roots were increased by NaHS pretreatment, while the ABA contents of leaves and roots decreased. This implied that there is complex crosstalk between these two signal molecules, and that the alleviation of drought stress by H2S, at least in part, involves the ABA signaling pathway. PMID:27649534

  14. Nuclear-localized AtHSPR links abscisic acid-dependent salt tolerance and antioxidant defense in Arabidopsis.

    Science.gov (United States)

    Yang, Tao; Zhang, Liang; Hao, Hongyan; Zhang, Peng; Zhu, Haowei; Cheng, Wei; Wang, Yongli; Wang, Xinyu; Wang, Chongying

    2015-12-01

    Salt stress from soil or irrigation water limits plant growth. A T-DNA insertion mutant in C24, named athspr (Arabidopsis thaliana heat shock protein-related), showed several phenotypes, including reduced organ size and enhanced sensitivity to environmental cues. The athspr mutant is severely impaired under salinity levels at which wild-type (WT) plants grow normally. AtHSPR encodes a nuclear-localized protein with ATPase activity, and its expression was enhanced by high salinity and abscisic acid (ABA). Overexpression (OE) of AtHSPR significantly enhanced tolerance to salt stress by increasing the activities of the antioxidant system and by maintaining K(+) /Na(+) homeostasis. Quantitative RT-PCR analyses showed that OE of AtHSPR increased the expression of ABA/stress-responsive, salt overly sensitive (SOS)-related and antioxidant-related genes. In addition, ABA content was reduced in athspr plants with or without salt stress, and exogenous ABA restored WT-like salt tolerance to athspr plants. athspr exhibited increased leaf stomatal density and stomatal index, slower ABA-induced stomatal closure and reduced drought tolerance relative to the WT. AtHSPR OE enhanced drought tolerance by reducing leaf water loss and stomatal aperture. Transcript profiling in athspr showed a differential salt-stress response for genes involved in accumulation of reactive oxygen species (ROS), ABA signaling, cell death, stress response and photosynthesis. Taken together, our results suggested that AtHSPR is involved in salt tolerance in Arabidopsis through modulation of ROS levels, ABA-dependent stomatal closure, photosynthesis and K(+) /Na(+) homeostasis.

  15. Tomato PYR/PYL/RCAR abscisic acid receptors show high expression in root, differential sensitivity to the abscisic acid agonist quinabactin, and the capability to enhance plant drought resistance.

    Science.gov (United States)

    González-Guzmán, Miguel; Rodríguez, Lesia; Lorenzo-Orts, Laura; Pons, Clara; Sarrión-Perdigones, Alejandro; Fernández, Maria A; Peirats-Llobet, Marta; Forment, Javier; Moreno-Alvero, Maria; Cutler, Sean R; Albert, Armando; Granell, Antonio; Rodríguez, Pedro L

    2014-08-01

    Abscisic acid (ABA) plays a crucial role in the plant's response to both biotic and abiotic stress. Sustainable production of food faces several key challenges, particularly the generation of new varieties with improved water use efficiency and drought tolerance. Different studies have shown the potential applications of Arabidopsis PYR/PYL/RCAR ABA receptors to enhance plant drought resistance. Consequently the functional characterization of orthologous genes in crops holds promise for agriculture. The full set of tomato (Solanum lycopersicum) PYR/PYL/RCAR ABA receptors have been identified here. From the 15 putative tomato ABA receptors, 14 of them could be grouped in three subfamilies that correlated well with corresponding Arabidopsis subfamilies. High levels of expression of PYR/PYL/RCAR genes was found in tomato root, and some genes showed predominant expression in leaf and fruit tissues. Functional characterization of tomato receptors was performed through interaction assays with Arabidopsis and tomato clade A protein phosphatase type 2Cs (PP2Cs) as well as phosphatase inhibition studies. Tomato receptors were able to inhibit the activity of clade A PP2Cs differentially in an ABA-dependent manner, and at least three receptors were sensitive to the ABA agonist quinabactin, which inhibited tomato seed germination. Indeed, the chemical activation of ABA signalling induced by quinabactin was able to activate stress-responsive genes. Both dimeric and monomeric tomato receptors were functional in Arabidopsis plant cells, but only overexpression of monomeric-type receptors conferred enhanced drought resistance. In summary, gene expression analyses, and chemical and transgenic approaches revealed distinct properties of tomato PYR/PYL/RCAR ABA receptors that might have biotechnological implications.

  16. Visualization of abscisic acid-perception sites on the plasma membrane of stomatal guard cells.

    Science.gov (United States)

    Yamazaki, Daiki; Yoshida, Shigeo; Asami, Tadao; Kuchitsu, Kazuyuki

    2003-07-01

    Abscisic acid (ABA) is a phytohormone that plays a key role as a stress signal, regulating water relations during drought conditions, by inducing stomatal closure. However, to date, no putative ABA receptor(s) has been reported at the protein sequence, gene family, or cellular localization levels. We used biotinylated ABA (bioABA) to characterize the ABA-perception sites in the stomatal guard cells of Vicia faba. Treatment with bioABA induced stomatal closure and shrinkage of guard cell protoplasts (GCPs). The ABA-perception sites were visualized by fluorescence microscopy and confocal laser scanning microscopy (CLSM), using bioABA and fluorescence-labeled avidin. Fluorescent particles were observed in patches on the surface of the GCPs. Fluorescence intensity was quantified by flow cytometry (FCM) as well as by CLSM. Binding of bioABA was inhibited by ABA in a dose-dependent manner. Pre-treatment of GCPs with proteinase K also blocked the binding of bioABA. Binding of bioABA was inhibited by RCA-7a, an ABA analog that induces stomatal closure, but not by RCA-16, which has no effect on stomatal aperture. Another ABA analog, PBI-51, inhibited ABA-induced stomatal closure. This ABA antagonist also inhibited binding of bioABA to the GCPs. These results suggest that ABA is perceived on the plasma membrane of stomatal guard cells, and that the present experimental methods constitute valuable tools for characterizing the nature of the ABA receptor(s) that perceives physiological ABA signals. These imaging studies allow us to demonstrate the spatial distribution of the ABA-perception sites. Visualization of the ABA-perception sites provides new insights into the nature of membrane-associated ABA receptor(s).

  17. Abscisic Acid accumulation in spinach leaf slices in the presence of penetrating and nonpenetrating solutes.

    Science.gov (United States)

    Creelman, R A; Zeevaart, J A

    1985-01-01

    Abscisic acid (ABA) accumulated in detached, wilted leaves of spinach (Spinacia oleracea L. cv Savoy Hybrid 612) and reached a maximum level within 3 to 4 hours. The increase in ABA over that found in detached turgid leaves was approximately 10-fold. The effects of water stress could be mimicked by the use of thin slices of spinach leaves incubated in the presence of 0.6 molar mannitol, a compound which causes plasmolysis (loss of turgor). About equal amounts of ABA were found both in the leaf slices and in detached leaves, whereas 2 to 4 times more ABA accumulated in the medium than in the slices. When spinach leaf slices were incubated with ethylene glycol, a compound which rapidly penetrates the cell membrane causing a decrease in the osmotic potential of the tissue and only transient loss of turgor, no ABA accumulated. Ethylene glycol was not inhibitory with respect to ABA accumulation. Spinach leaf slices incubated in both ethylene glycol and mannitol had ABA levels similar to those found when slices were incubated with mannitol alone. Increases similar to those found with mannitol also occurred when Aquacide III, a highly purified form of polyethylene glycol, was used. Aquacide III causes cytorrhysis, a situation similar to that found in wilted leaves. Thus, it appears that loss of turgor is essential for ABA accumulation.When spinach leaf slices were incubated with solutes which are supposed to disturb membrane integrity (KHSO(3), 2-propanol, or KCl) no increase in ABA was observed. These data indicate that, with respect to the accumulation of ABA, mannitol caused a physical stress (loss of turgor) rather than a chemical stress (membrane damage).

  18. Influence Mechanism of Endogenous Abscisic Acid on Storage Softening Process of Hardy Kiwifruit

    Directory of Open Access Journals (Sweden)

    Li Shuqian

    2014-01-01

    Full Text Available In order to study the relation of Abscisic Acid (ABA with other biochemistry factors during hardy kiwifruit softening process. The changing trend of ABA under the fruits storage conditions of 20 and 0C was analyzed. A conclusion is drawn as below: During storage under 20C, it shows the highest content of ABA in 4 days to 222.19 &mu g/L, which reaches the almost same content in 3 and 5 days. The value keeps inclining since 5 days and decline rate is lower in 7 and 8 days. The lowest value is reached to 20.88 &mug/L in 10 days. During storage under 0C, ABA content is at a relatively high level but shows the slow down trend. ABA content falls greatly from 9 to 11 days. After this period, ABA content still follows up-trend and declining then. The peak appears in 15 days to 90.49 &mug/L, but it is lower than that in the first nine days. Moreover, peak during storage in environment under 0C is lower than that during the storage in environment at normal temperature, accordingly delaying fruit softening. As the ABA content rises to the highest level, the fruit hardness drops drastically. When ABA content slightly changes, the hardness decreases gently. ABA content is featured that same changing trend of ethylene content, respiratory intensity, pectase content and amylase content. Moreover, ABA has the same peak appearance time as amylase but it is later than appearance of both pectase and ethylene, they basically match each other. The rule of peak appearance time is not obvious for ABA and amylase. Mutual inhibition exists between peak appearance time of ABA and respiratory intensity. Quick ABA rise is accompanied with slow amylase rise and vice versa.

  19. A maize calcium-dependent protein kinase gene, ZmCPK4, positively regulated abscisic acid signaling and enhanced drought stress tolerance in transgenic Arabidopsis.

    Science.gov (United States)

    Jiang, Shanshan; Zhang, Dan; Wang, Li; Pan, Jiaowen; Liu, Yang; Kong, Xiangpei; Zhou, Yan; Li, Dequan

    2013-10-01

    Calcium-dependent protein kinases (CDPKs) play essential roles in calcium-mediated signal transductions in plant response to abiotic stress. Several members have been identified to be regulators for plants response to abscisic acid (ABA) signaling. Here, we isolated a subgroup I CDPK gene, ZmCPK4, from maize. Quantitative real time PCR (qRT-PCR) analysis revealed that the ZmCPK4 transcripts were induced by various stresses and signal molecules. Transient and stable expression of the ZmCPK4-GFP fusion proteins revealed ZmCPK4 localized to the membrane. Moreover, overexpression of ZmCPK4 in the transgenic Arabidopsis enhanced ABA sensitivity in seed germination, seedling growth and stomatal movement. The transgenic plants also enhanced drought stress tolerance. Taken together, the results suggest that ZmCPK4 might be involved in ABA-mediated regulation of stomatal closure in response to drought stress.

  20. Effect of auxin and abscisic acid on cell wall extensibility in maize coleoptiles.

    Science.gov (United States)

    Kutschera, U; Schopfer, P

    1986-04-01

    Plastic and elastic in-vitro extensibilities (E pland E el ) of cell walls from growing maize (Zea mays L.) coleoptile segments were measured by stretching frozen-thawed tissue, pre-extended to its in-vivo length, at constant force (creep test) in a custom-buildt extensiometer, equipped with a linear-displacement transducer. The indole-3-acetic acid (IAA)-induced change of E pl (ΔE pl ) is strictly correlated with the growth rate for a period of 3-4 h. Subsequently, ΔE plremains constant while the growth rate is slowing down. Since this discrepancy can be accounted for by a growth-dependent reduction of osmotic pressure, it is concluded that ΔE plrepresents quantitatively the relative increase of in-vivo extensibility (cell wall loosening) involved in IAA-mediated cell growth over a much longer time. On the other side it is argued that the growth rate may not be strictly correlated with wall extensibility during long-term growth. Abscisic acid (ABA) inhibits segment growth induced by auxin, fusicoccin, or exogenous acid, and this effect can be quantitatively attributed to an ABA-mediated reduction of cell wall extensibility as determined by the ΔE plmeasurement. Both, IAA and ABA have no effect on total protein synthesis, RNA synthesis, and amount of osmotic solutes. Fusicoccin-induced proton excretion is only slightly inhibited by ABA. In contrast to ABA, growth inhibition by cycloheximide (CHI) is always much larger than the concomitant reduction of ΔE pl , indicating that a further growth parameter is also involved in the inhibition of cell growth by CHI. ΔE el is not affected by either IAA, ABA, or CHI. It is concluded that δE pl as determined by the applied method, represents a relative measure of the actual in-vivo extensibility of the growing cell wall at the very moment when the tissue is killed, rather than an average extensibility accumulated over some immediate-past period of time as suggested by Cleland (1984, Planta 160, 514-520). Hence, we

  1. Alleviation of Osmotic Stress Effects by Exogenous Application of Salicylic or Abscisic Acid on Wheat Seedlings

    Directory of Open Access Journals (Sweden)

    Katarzyna Cyganek

    2013-06-01

    Full Text Available The aim of the study was to assess the role of salicylic acid (SA and abscisic acid (ABA in osmotic stress tolerance of wheat seedlings. This was accomplished by determining the impact of the acids applied exogenously on seedlings grown under osmotic stress in hydroponics. The investigation was unique in its comprehensiveness, examining changes under osmotic stress and other conditions, and testing a number of parameters simultaneously. In both drought susceptible (SQ1 and drought resistant (CS wheat cultivars, significant physiological and biochemical changes were observed upon the addition of SA (0.05 mM or ABA (0.1 μM to solutions containing half-strength Hoagland medium and PEG 6000 (−0.75 MPa. The most noticeable result of supplementing SA or ABA to the medium (PEG + SA and PEG + ABA was a decrease in the length of leaves and roots in both cultivars. While PEG treatment reduced gas exchange parameters, chlorophyll content in CS, and osmotic potential, and conversely, increased lipid peroxidation, soluble carbohydrates in SQ1, proline content in both cultivars and total antioxidants activity in SQ1, PEG + SA or PEG + ABA did not change the values of these parameters. Furthermore, PEG caused a two-fold increase of endogenous ABA content in SQ1 and a four-fold increase in CS. PEG + ABA increased endogenous ABA only in SQ1, whereas PEG + SA caused a greater increase of ABA content in both cultivars compared to PEG. In PEG-treated plants growing until the harvest, a greater decrease of yield components was observed in SQ1 than in CS. PEG + SA, and particularly PEG + ABA, caused a greater increase of these yield parameters in CS compared to SQ1. In conclusion, SA and ABA ameliorate, particularly in the tolerant wheat cultivar, the harmful effects and after effects of osmotic stress induced by PEG in hydroponics through better osmotic adjustment achieved by an increase in proline and carbohydrate content as well as by an increase in antioxidant

  2. Dietary abscisic acid ameliorates influenza-virus-associated disease and pulmonary immunopathology through a PPARγ-dependent mechanism.

    Science.gov (United States)

    Hontecillas, Raquel; Roberts, Paul C; Carbo, Adria; Vives, Cristina; Horne, William T; Genis, Sandra; Velayudhan, Binu; Bassaganya-Riera, Josep

    2013-06-01

    The anti-inflammatory phytohormone abscisic acid (ABA) modulates immune and inflammatory responses in mouse models of colitis and obesity. ABA has been identified as a ligand of lanthionine synthetase C-like 2, a novel therapeutic target upstream of the peroxisome proliferator-activated receptor γ (PPARγ) pathway. The goal of this study was to investigate the immune modulatory mechanisms underlying the anti-inflammatory efficacy of ABA against influenza-associated pulmonary inflammation. Wild-type (WT) and conditional knockout mice with defective PPARγ expression in lung epithelial and hematopoietic cells (cKO) treated orally with or without ABA (100 mg/kg diet) were challenged with influenza A/Udorn (H3N2) to assess ABA's impact in disease, lung lesions and gene expression. Dietary ABA ameliorated disease activity and lung inflammatory pathology, accelerated recovery and increased survival in WT mice. ABA suppressed leukocyte infiltration and monocyte chemotactic protein 1 mRNA expression in WT mice through PPARγ since this effect was abrogated in cKO mice. ABA ameliorated disease when administered therapeutically on the same day of the infection to WT but not mice lacking PPARγ in myeloid cells. We also show that ABA's greater impact is between days 7 and 10 postchallenge when it regulates the expression of genes involved in resolution, like 5-lipoxygenase and other members of the 5-lipoxygenase pathway. Furthermore, ABA significantly increased the expression of the immunoregulatory cytokine interleukin-10 in WT mice. Our results show that ABA, given preventively or therapeutically, ameliorates influenza-virus-induced pathology by activating PPARγ in pulmonary immune cells, suppressing initial proinflammatory responses and promoting resolution.

  3. Studies on the growth and indole-3-acetic acid and abscisic acid content of Zea mays seedlings grown in microgravity

    Science.gov (United States)

    Schulze, A.; Jensen, P. J.; Desrosiers, M.; Buta, J. G.; Bandurski, R. S.

    1992-01-01

    Measurements were made of the fresh weight, dry weight, dry weight-fresh weight ratio, free and conjugated indole-3-acetic acid, and free and conjugated abscisic acid in seedlings of Zea mays grown in darkness in microgravity and on earth. Imbibition of the dry kernels was 17 h prior to launch. Growth was for 5 d at ambient orbiter temperature and at a chronic accelerational force of the order of 3 x 10(-5) times earth gravity. Weights and hormone content of the microgravity seedlings were, with minor exceptions, not statistically different from seedlings grown in normal gravity. The tissues of the shuttle-grown plants appeared normal and the seedlings differed only in the lack of orientation of roots and shoots. These findings, based upon 5 d of growth in microgravity, cannot be extrapolated to growth in microgravity for weeks, months, and years, as might occur on a space station. Nonetheless, it is encouraging, for prospects of bioregeneration of the atmosphere and food production in a space station, that no pronounced differences in the parameters measured were apparent during the 5 d of plant seedling growth in microgravity.

  4. Growth and graviresponsiveness of primary roots of Zea mays seedlings deficient in abscisic acid and gibberellic acid

    Science.gov (United States)

    Moore, R.; Dickey, K.

    1985-01-01

    The objective of this research was to determine if gibberellic acid (GA) and/or abscisic acid (ABA) are necessary for graviresponsiveness by primary roots of Zea mays. To accomplish this objective we measured the growth and graviresponsiveness of primary roots of seedlings in which the synthesis of ABA and GA was inhibited collectively and individually by genetic and chemical means. Roots of seedlings treated with Fluridone (an inhibitor of ABA biosynthesis) and Ancymidol (an inhibitor of GA biosynthesis) were characterized by slower growth rates but not significantly different gravicultures as compared to untreated controls. Gravicurvatures of primary roots of d-5 mutants (having undetectable levels of GA) and vp-9 mutants (having undectable levels of ABA) were not significantly different from those of wild-type seedlings. Roots of seedlings in which the biosynthesis of ABA and GA was collectively inhibited were characterized by gravicurvatures not significantly different for those of controls. These results (1) indicate that drastic reductions in the amount of ABA and GA in Z. mays seedlings do not significantly alter root graviresponsiveness, (2) suggest that neither ABA nor GA is necessary for root gravicurvature, and (3) indicate that root gravicurvature is not necessarily proportional to root elongation.

  5. Roles of gibberellins and abscisic acid in dormancy and germination of red bayberry (Myrica rubra) seeds.

    Science.gov (United States)

    Chen, Shun-Ying; Kuo, Shing-Rong; Chien, Ching-Te

    2008-09-01

    Intact seeds from freshly harvested fruits of Myrica rubra (Sieb et Zucc.) were dormant and required 8 weeks of warm stratification followed by 12 weeks of cold stratification for germination. Exogenous application of gibberellic acid (GA(3)) to intact fresh seeds was effective in breaking dormancy, with > 70% of seeds germinating when treated with 5.2 mM GA(3) and incubated at a day/night temperature of 30/20 degrees C for 20 weeks. Removing the hard endocarp or endocarp plus seed coat of fresh seeds promoted germination, and addition of GA(3) to the embryo accelerated germination. The gibberellins GA(1) and GA(4) were more effective than GA(3) in promoting germination of seeds with the endocarp removed. Endogenous contents of GA(1), GA(3), GA(4), GA(7) and GA(20) were quantified by gas chromatography-mass spectrometry-selected ion monitoring in the endocarps, seed coats and embryos of fresh seeds treated with 5.2 mM GA(3). The content of GA(3) decreased in the endocarp during incubation, whereas GA(1) contents increased in the endocarp and seed coat. A high GA(1) content was detected in the endocarps and embryos of newly germinated seeds. We speculate that GA(3) was converted to GA(1) during incubation and that GA(1) is involved in seed germination. Endogenous abscisic acid (ABA) contents were measured in fresh seeds and in warm and cold stratified seeds. The ABA content in fresh seeds was distributed in the order endocarp > seed coat > embryo, with the content in the endocarp being about 132-fold higher than in the seed coat and embryo. Total ABA content of seeds subjected to warm or cold stratification, or both, was 8.7- to 14.0-fold lower than that of fresh seeds. Low contents of endogenous GA(1), GA(3), GA(7) and GA(20), but elevated contents of GA(4), were found in the seed coats and endocarps of warm plus cold stratified seeds and in the seed coats and embryos of newly germinated seeds. These observations, coupled with the finding that GA stimulated

  6. Localization and interaction of the cis-acting elements for abscisic acid, VIVIPAROUS1, and light activation of the C1 gene of maize.

    Science.gov (United States)

    Kao, C Y; Cocciolone, S M; Vasil, I K; McCarty, D R

    1996-07-01

    The C1 regulatory gene of the maize anthocyanin pathway is regulated by a combination of developmental and environmental signals that include the Viviparous1 (Vp1) gene, abscisic acid (ABA), and light. Using protoplast electroporation and particle bombardment assays, we have defined c/s-acting elements that are necessary and sufficient for the activation of C1 by ABA, VP1, and light, respectively. The sequence from positions -142 to -132 (CGTCCATGCAT) is essential for VP1 activation, whereas a larger overlapping element from -147 to -132 (CGTGTCGTCCATGCAT) is necessary and sufficient for activation by ABA. A separate light (blue and red)-responsive c/s element is located between positions -116 and -59. Light interacts synergistically with the ABA and VP1 responses in transient expression assays, suggesting that combinatorial interaction between modules plays a role in integrating these signals in the developing seed.

  7. Structural basis for basal activity and autoactivation of abscisic acid (ABA) signaling SnRK2 kinases

    Energy Technology Data Exchange (ETDEWEB)

    Ng, Ley-Moy; Soon, Fen-Fen; Zhou, X. Edward; West, Graham M.; Kovach, Amanda; Suino-Powell, Kelly M.; Chalmers, Michael J.; Li, Jun; Yong, Eu-Leong; Zhu, Jian-Kang; Griffin, Patrick R.; Melcher, Karsten; Xu, H. Eric (Van Andel); (Scripps); (Purdue); (NU Singapore)

    2014-10-02

    Abscisic acid (ABA) is an essential hormone that controls plant growth, development, and responses to abiotic stresses. Central for ABA signaling is the ABA-mediated autoactivation of three monomeric Snf1-related kinases (SnRK2.2, -2.3, and -2.6). In the absence of ABA, SnRK2s are kept in an inactive state by forming physical complexes with type 2C protein phosphatases (PP2Cs). Upon relief of this inhibition, SnRK2 kinases can autoactivate through unknown mechanisms. Here, we report the crystal structures of full-length Arabidopsis thaliana SnRK2.3 and SnRK2.6 at 1.9- and 2.3-{angstrom} resolution, respectively. The structures, in combination with biochemical studies, reveal a two-step mechanism of intramolecular kinase activation that resembles the intermolecular activation of cyclin-dependent kinases. First, release of inhibition by PP2C allows the SnRK2s to become partially active because of an intramolecular stabilization of the catalytic domain by a conserved helix in the kinase regulatory domain. This stabilization enables SnRK2s to gain full activity by activation loop autophosphorylation. Autophosphorylation is more efficient in SnRK2.6, which has higher stability than SnRK2.3 and has well-structured activation loop phosphate acceptor sites that are positioned next to the catalytic site. Together, these data provide a structural framework that links ABA-mediated release of PP2C inhibition to activation of SnRK2 kinases.

  8. Daily irrigation attenuates xylem abscisic acid concentration and increases leaf water potential of Pelargonium × hortorum compared with infrequent irrigation.

    Science.gov (United States)

    Boyle, Richard K A; McAinsh, Martin; Dodd, Ian C

    2016-09-01

    The physiological response of plants to different irrigation frequencies may affect plant growth and water use efficiency (WUE; defined as shoot biomass/cumulative irrigation). Glasshouse-grown, containerized Pelargonium × hortorum BullsEye plants were irrigated either daily at 100% of plant evapotranspiration (ET) (well-watered; WW), or at 50% ET applied either daily [frequent deficit irrigation (FDI)] or cumulatively every 4 days [infrequent deficit irrigation (IDI)], for 24 days. Both FDI and IDI applied the same irrigation volume. Xylem sap was collected from the leaves, and stomatal conductance (gs ) and leaf water potential (Ψleaf ) measured every 2 days. As soil moisture decreased, gs decreased similarly under both FDI and IDI throughout the experiment. Ψleaf was maintained under IDI and increased under FDI. Leaf xylem abscisic acid (ABA) concentrations ([X-ABA]leaf ) increased as soil moisture decreased under both IDI and FDI, and was strongly correlated with decreased gs , but [X-ABA]leaf was attenuated under FDI throughout the experiment (at the same level of soil moisture as IDI plants). These physiological changes corresponded with differences in plant production. Both FDI and IDI decreased growth compared with WW plants, and by the end of the experiment, FDI plants also had a greater shoot fresh weight (18%) than IDI plants. Although both IDI and FDI had higher WUE than WW plants during the first 10 days of the experiment (when biomass did not differ between treatments), the deficit irrigation treatments had lower WUE than WW plants in the latter stages when growth was limited. Thus, ABA-induced stomatal closure may not always translate to increased WUE (at the whole plant level) if vegetative growth shows a similar sensitivity to soil drying, and growers must adapt their irrigation scheduling according to crop requirements.

  9. Abscisic acid regulates pinoresinol-lariciresinol reductase gene expression and secoisolariciresinol accumulation in developing flax (Linum usitatissimum L.) seeds.

    Science.gov (United States)

    Renouard, Sullivan; Corbin, Cyrielle; Lopez, Tatiana; Montguillon, Josiane; Gutierrez, Laurent; Lamblin, Frédéric; Lainé, Eric; Hano, Christophe

    2012-01-01

    Secoisolariciresinol diglucoside (SDG), the main phytoestrogenic lignan of Linum usitatissimum, is accumulated in the seed coat of flax during its development and pinoresinol-lariciresinol reductase (PLR) is a key enzyme in flax for its synthesis. The promoter of LuPLR1, a flax gene encoding a pinoresinol lariciresinol reductase, contains putative regulatory boxes related to transcription activation by abscisic acid (ABA). Gel mobility shift experiments evidenced an interaction of nuclear proteins extracted from immature flax seed coat with a putative cis-acting element involved in ABA response. As ABA regulates a number of physiological events during seed development and maturation we have investigated its involvement in the regulation of this lignan synthesis by different means. ABA and SDG accumulation time courses in the seed as well as LuPLR1 expression were first determined in natural conditions. These results showed that ABA timing and localization of accumulation in the flax seed coat could be correlated with the LuPLR1 gene expression and SDG biosynthesis. Experimental modulations of ABA levels were performed by exogenous application of ABA or fluridone, an inhibitor of ABA synthesis. When submitted to exogenous ABA, immature seeds synthesized 3-times more SDG, whereas synthesis of SDG was reduced in immature seeds treated with fluridone. Similarly, the expression of LuPLR1 gene in the seed coat was up-regulated by exogenous ABA and down-regulated when fluridone was applied. These results demonstrate that SDG biosynthesis in the flax seed coat is positively controlled by ABA through the transcriptional regulation of LuPLR1 gene.

  10. Functional analysis of TaABF1 during abscisic acid and gibberellin signalling in aleurone cells of cereal grains.

    Science.gov (United States)

    Harris, Lauren J; Martinez, Sarah A; Keyser, Benjamin R; Dyer, William E; Johnson, Russell R

    2013-06-01

    The wheat transcription factor TaABF1 physically interacts with the protein kinase PKABA1 and mediates both abscisic acid (ABA)-induced and ABA-suppressed gene expression. In bombarded aleurone cells of imbibing grains, the effect of TaABF1 in down-regulating the gibberellin (GA)-induced Amy32b promoter was stronger in the presence of exogenous ABA. As these grains contained low levels of endogenous ABA, the effect of TaABF1 may also be mediated by ABA-induced activation even in the absence of exogenous ABA. Levels of TaABF1 protein decreased slightly during imbibition of afterripened grains. However, TaABF1 levels (especially in aleurone layers) were not substantially affected by exogenous ABA or GA, indicating that changes in TaABF1 protein level are not an important part of regulating its role in hormone signalling. We found that TaABF1 was phosphorylated in vivo in aleurone cells, suggesting a role for post-translational modification in regulating TaABF1 activity. Induction of Amy32b by overexpression of the transcription factor GAMyb could not be prevented by TaABF1, indicating that TaABF1 acts upstream of GAMyb transcription in the signalling pathway. Supporting this view, knockdown of TaABF1 by RNA interference resulted in increased expression from the GAMyb promoter. These results are consistent with a model in which TaABF1 is constitutively present in aleurone cells, while its ability to down-regulate GAMyb is regulated in response to ABA.

  11. Profiling the dynamics of abscisic acid and ABA-glucose ester after using the glucosyltransferase UGT71C5 to mediate abscisic acid homeostasis in Arabidopsis thaliana by HPLC-ESI-MS/MS

    Institute of Scientific and Technical Information of China (English)

    Dong-Mei Xiong; Zhen Liu; Han Chen; Jin-Tao Xue; Yi Yang; Cong Chen; Li-Ming Ye

    2014-01-01

    The HPLC-MS/MS method was developed to profile the dynamics of abscisic acid (ABA) and ABA-glucose ester (ABA-GE) after cloning glycosyltransferase enzyme family gene AtUGT71C5 into Arabidopsis thaliana. By constructing over-expression lines (OE) and down-expression lines (DN), we acquired mutant strains to analyze the function of AtUGT71C5. The multiple-reaction monitoring (MRM) was used for quantitative determination in negative mode. The transition was m/z 263.1-153.0 for ABA ([M-H]þ), m/z 425.1-263.0 for ABA-GE ([M-H]þ), and m/z 321.0-152.0 for chloramphe-nicol. The linear range was 0.8684-217.1 ng/mL for ABA and 0.3920-196.0 ng/mL for ABA-GE. The accuracy was 88.0-109.0% for ABA and 86.6-113.0% for ABA-GE; the inter-day and intra-day precisions were less than 5.4%for ABA and 8.9%for ABA-GE, respectively. This method is simple and sensitive enough for determination of ABA and ABA-GE in A. thaliana leaves. All the evidence confirmed the speculation that AtUGT71C5 can mediate abscisic acid homeostasis.

  12. The role of zeatin and gibberellic acid in breaking of the abscisic acid-induced dormancy in Triticale caryopses

    Directory of Open Access Journals (Sweden)

    Stanisław Weidner

    2014-01-01

    Full Text Available The investigations were conducted on the germinating embryos and the whole caryopses of Triticale. During preimbibition and 24 hours germination caryopses were treated with abscisic acid (ABA, which produced 63% inhibition of embryo growth. Gibberellin-A3 (GA3 reversed the ABA effect in 18%, while zeatin in 22%. The clear synergic reaction was observed (36% when both stimulators acted together. There was no significant effect of ABA, ABA and GA3, as well as ABA and zeatin on the synthesis of polyribosomal RNA in the initial period of germination of excised embryos. However, during 24 hours germination of whole caryopses ABA caused a twofold decrease in 3H-uridine incorporation into the total fraction of embryonic ribosomes. While the incorporation of 14C-aminoacid mixture into ribosomal proteins was even three-fold lower. Effect of GA3 and zeatin on breaking of the ABA-induced "dormancy" was studied. It was confirmed that the higher polyribosome contribution to the sum total of ribosomes the more intensive synthesis of ribosomal proteins. No higher 3H-uridine incorporation into polyribosomal fraction was observed. From the results it may be inferred that in the initial period of germination of Triticale caryopses regulation of protein biosynthesis occurs rather at the translation than transcription level.

  13. Arabidopsis AtDjA3 null mutant shows increased sensitivity to abscisic acid, salt, and osmotic stress in germination and postgermination stages

    Directory of Open Access Journals (Sweden)

    Silvia eSalas-Muñoz

    2016-02-01

    Full Text Available DnaJ proteins are essential co-chaperones involved in abiotic and biotic stress responses. Arabidopsis AtDjA3 gene encodes a molecular co-chaperone of 420 amino acids, which belongs to the J-protein family. In this study, we report the functional characterization of the AtDjA3 gene using the Arabidopsis knockout line designated j3 and the 35S::AtDjA3 overexpression lines. Loss of AtDjA3 function was associated with small seed production. In fact, j3 mutant seeds showed a reduction of 24% in seed weight compared to Col-0 seeds. Expression analysis showed that the AtDjA3 gene was modulated in response to NaCl, glucose, and abscisic acid. The j3 line had increased sensitivity to NaCl and glucose treatments in the germination and cotyledon development in comparison to parental Col-0. Furthermore, the j3 mutant line exhibited higher abscisic acid sensitivity in comparison to parental Col-0 and 35S::AtDjA3 overexpression lines. In addition, we examined the expression of ABI3 gene, which is a central regulator in ABA signalling, in j3 mutant and 35S::AtDjA3 overexpression lines. Under 5 μM ABA treatment at 24 h, j3 mutant seedlings displayed higher ABI3 expression, whereas in 35S::AtDjA3 overexpression lines, ABI3 gene expression was repressed. Taken together, these results demonstrate that the AtDjA3 gene is involved in seed development and abiotic stress tolerance.

  14. Effects of abscisic acid, gibberellic acid and fusicoccin on the transmembrane potential during the early phases of germination in radish (Raphanus sativus L.) seeds.

    Science.gov (United States)

    Ballarin-Denti, A; Cocucci, M

    1979-01-01

    During germination, the transmembrane electric potential (PD) of cortical cells of the embryonal axis of radish seeds (Raphanus sativus L.) rises from-120 mV initially to a maximum of-150 mV after 5 h incubation, then falls again to stable values of around-120 mV. Treatments inhibiting germination block the transitory PD increase. Administration of uncoupling agents or low temperatures, during the process of germination, produces a marked fall of the PD transitory increase. Abscisic Acid has a parallel inhibitory effect on PD and germination, while fusicoccin produces a rise in both; administration of abscisic acid with fusicoccin inhibits germination, while the PD remains at the high levels given by fusicoccin. These results are discussed in relation to ion exchange at membrane level.

  15. Conclusion on the peer review of the pesticide risk assessment of the active substance S-abscisic acid

    Directory of Open Access Journals (Sweden)

    European Food Safety Authority

    2013-08-01

    Full Text Available The conclusions of the European Food Safety Authority (EFSA following the peer review of the initial risk assessments carried out by the competent authority of the rapporteur Member State the Netherlands, for the pesticide active substance S-abscisic acid are reported. The context of the peer review was that required by Commission Regulation EU No 188/2011. The conclusions were reached on the basis of the evaluation of the representative uses of S-abscisic acid as a plant growth regulator on tomato seedlings and grapes. The reliable endpoints concluded as being appropriate for use in regulatory risk assessment, derived from the available studies and literature in the dossier peer reviewed, are presented. Missing information identified as being required by the regulatory framework is listed. Concerns are identified in the areas of residues and ecotoxicology, as the consumer risk assessment and the risk assessment for higher aquatic plants for some metabolites could not be finalised based on the data available.

  16. The Arabidopsis aleurone layer responds to nitric oxide, gibberellin, and abscisic acid and is sufficient and necessary for seed dormancy.

    Science.gov (United States)

    Bethke, Paul C; Libourel, Igor G L; Aoyama, Natsuyo; Chung, Yong-Yoon; Still, David W; Jones, Russell L

    2007-03-01

    Seed dormancy is a common phase of the plant life cycle, and several parts of the seed can contribute to dormancy. Whole seeds, seeds lacking the testa, embryos, and isolated aleurone layers of Arabidopsis (Arabidopsis thaliana) were used in experiments designed to identify components of the Arabidopsis seed that contribute to seed dormancy and to learn more about how dormancy and germination are regulated in this species. The aleurone layer was found to be the primary determinant of seed dormancy. Embryos from dormant seeds, however, had a lesser growth potential than those from nondormant seeds. Arabidopsis aleurone cells were examined by light and electron microscopy, and cell ultrastructure was similar to that of cereal aleurone cells. Arabidopsis aleurone cells responded to nitric oxide (NO), gibberellin (GA), and abscisic acid, with NO being upstream of GA in a signaling pathway that leads to vacuolation of protein storage vacuoles and abscisic acid inhibiting vacuolation. Molecular changes that occurred in embryos and aleurone layers prior to germination were measured, and these data show that both the aleurone layer and the embryo expressed the NO-associated gene AtNOS1, but only the embryo expressed genes for the GA biosynthetic enzyme GA3 oxidase.

  17. Onset of herbivore-induced resistance in systemic tissue primed for jasmonate-dependent defenses is activated by abscisic acid

    Directory of Open Access Journals (Sweden)

    Irene A. Vos

    2013-12-01

    Full Text Available In Arabidopsis, the MYC2 transcription factor on the one hand and the AP2/ERF transcription factors ORA59 and ERF1 on the other hand regulate distinct branches of the jasmonic acid (JA signaling pathway in an antagonistic fashion, co-regulated by abscisic acid (ABA and ethylene, respectively. Feeding by larvae of the specialist herbivorous insect Pieris rapae (small cabbage white butterfly results in activation of the MYC-branch and concomitant suppression of the ERF-branch in insect-damaged leaves. Here we investigated differential JA signaling activation in undamaged systemic leaves of P. rapae-infested plants. We found that the MYC2 transcription factor gene was induced both in the local insect-damaged leaves and the systemic undamaged leaves of P. rapae-infested Arabidopsis plants. However, in contrast to the insect-damaged leaves, the undamaged tissue did not show activation of the MYC-branch marker gene VSP1. Comparison of the hormone signal signature revealed that the levels of JA and (+-7-iso-jasmonoyl-L-isoleucine (JA-Ile raised to similar extents in locally damaged and systemically undamaged leaves, but the production of ABA and the JA precursor 12-oxo-phytodienoic acid (OPDA was enhanced only in the local herbivore-damaged leaves, and not in the distal undamaged leaves. Challenge of undamaged leaves of pre-infested plants with either P. rapae larvae or exogenously applied ABA led to potentiated expression levels of MYC2 and VSP1, with the latter reaching extremely high expression levels. Moreover, P. rapae-induced resistance, as measured by reduction of caterpillar growth on pre-infested plants, was blocked in the ABA biosynthesis mutant aba2-1, that was also impaired in P. rapae-induced expression of VSP1. Together, these results suggest that ABA is a crucial regulator of herbivore-induced resistance by activating primed JA-regulated defense responses upon secondary herbivore attack in Arabidopsis.

  18. Comparative effects of auxin and abscisic acid on growth, hydrogen ion efflux and gravitropism in primary roots of maize

    Science.gov (United States)

    Evans, M. L.; Mulkey, T. J.

    1984-01-01

    In order to test the idea that auxin action on root growth may be mediated by H(+) movement, the correlation of auxin action on growth and H(+) movement in roots was examined along with changes in H(+) efflux patterns associated with the asymmetric growth which occurs during gravitropism. The effects of indoleacetic acid (IAA) and abscisic acid (AbA) on growth, H(+) secretion, and gravitropism in roots were compared. Results show a close correlation existent between H(+) efflux and growth in maize roots. In intact roots there is strong H(+) efflux from the elongation zone. Growth-promoting concentrations of IAA stimulate H(+) efflux. During gravitropism the H(+) efflux from the elongation zone becomes asymmetric; the evidence indicates that auxin redistribution contributes to the development of acid efflux asymmetry. That AbA stimulates root growth is reflected in its ability to stimulate H(+) efflux from apical root segments.

  19. Hardening with salicylic acid induces concentration-dependent changes in abscisic acid biosynthesis of tomato under salt stress.

    Science.gov (United States)

    Horváth, Edit; Csiszár, Jolán; Gallé, Ágnes; Poór, Péter; Szepesi, Ágnes; Tari, Irma

    2015-07-01

    The role of salicylic acid (SA) in the control of abscisic acid (ABA) biosynthesis is controversial although both plant growth regulators may accumulate in tissues under abiotic and biotic stress conditions. Hardening of tomato plants to salinity stress with 10(-4)M SA ("high SA") resulted in an up-regulation of ABA biosynthesis genes, zeaxanthin epoxidase (SlZEP1), 9-cis-epoxycarotenoid dioxygenase (SlNCED1) and aldehyde oxidases (SlAO1 and SlAO2) in the roots and led to ABA accumulation both in root and leaf tissues. In plants pre-treated with lower concentration of SA (10(-7)M, "low SA"), the up-regulation of SlNCED1 in the roots promoted ABA accumulation in the root tissues but the hormone concentration remained at control level in the leaves. Salt stress induced by 100mM NaCl reduced the transcript abundance of ABA biosynthetic genes and inhibited SlAO activity in plants hardened with "high SA", but the tissues maintained root ABA level over the untreated control. The combined effect of "high SA" and ABA under salt stress led to partially recovered photosynthetic activity, reduced ethylene production in root apices, and restored root growth, which is one of the main features of salt tolerance. Unlike "high SA", hardening with "low SA" had no influence on ethylene production, and led to reduced elongation of roots in plants exposed to 100mM NaCl. The up-regulation of carotenoid cleavage dioxygenases SlCCD1A and SlCCD1B by SA, which produce apocarotenoids, may open new pathways in SA sensing and signalling processes.

  20. In vivo characterization of the effects of abscisic acid and drying protocols associated with the acquisition of desiccation tolerance in alfalfa (Medicago sativa L.) somatic embryos

    NARCIS (Netherlands)

    Sreedhar, L.; Wolkers, W.F.; Hoekstra, F.A.; Bewley, J.D.

    2002-01-01

    Although somatic embryos of alfalfa (Medicago sativa L.) had acquired some tolerance to desiccation at the cotyledonary stage of development (22 d after plating), additional culturing in 20 ?M abscisic acid (ABA) for 8 d induced greater desiccation tolerance, as determined by increased germination.

  1. Characterization of major ripening events during softening in grape: turgor, sugar accumulation, abscisic acid metabolism, colour development, and their relationship with growth.

    Science.gov (United States)

    Castellarin, Simone D; Gambetta, Gregory A; Wada, Hiroshi; Krasnow, Mark N; Cramer, Grant R; Peterlunger, Enrico; Shackel, Kenneth A; Matthews, Mark A

    2016-02-01

    Along with sugar accumulation and colour development, softening is an important physiological change during the onset of ripening in fruits. In this work, we investigated the relationships among major events during softening in grape (Vitis vinifera L.) by quantifying elasticity in individual berries. In addition, we delayed softening and inhibited sugar accumulation using a mechanical growth-preventing treatment in order to identify processes that are sugar and/or growth dependent. Ripening processes commenced on various days after anthesis, but always at similarly low elasticity and turgor. Much of the softening occurred in the absence of other changes in berry physiology investigated here. Several genes encoding key cell wall-modifying enzymes were not up-regulated until softening was largely completed, suggesting softening may result primarily from decreases in turgor. Similarly, there was no decrease in solute potential, increase in sugar concentration, or colour development until elasticity and turgor were near minimum values, and these processes were inhibited when berry growth was prevented. Increases in abscisic acid occurred early during softening and in the absence of significant expression of the V. vinifera 9-cis-epoxycarotenoid dioxygenases. However, these increases were coincident with decreases in the abscisic acid catabolite diphasic acid, indicating that initial increases in abscisic acid may result from decreases in catabolism and/or exogenous import. These data suggest that softening, decreases in turgor, and increases in abscisic acid represent some of the earliest events during the onset of ripening. Later, physical growth, further increases in abscisic acid, and the accumulation of sugar are integral for colour development.

  2. Interaction of Polyamines, Abscisic Acid, Nitric Oxide, and Hydrogen Peroxide under Chilling Stress in Tomato (Lycopersicon esculentum Mill.) Seedlings.

    Science.gov (United States)

    Diao, Qiannan; Song, Yongjun; Shi, Dongmei; Qi, Hongyan

    2017-01-01

    Polyamines (PAs) play a vital role in the responses of higher plants to abiotic stresses. However, only a limited number of studies have examined the interplay between PAs and signal molecules. The aim of this study was to elucidate the cross-talk among PAs, abscisic acid (ABA), nitric oxide (NO), and hydrogen peroxide (H2O2) under chilling stress conditions using tomato seedlings [(Lycopersicon esculentum Mill.) cv. Moneymaker]. The study showed that during chilling stress (4°C; 0, 12, and 24 h), the application of spermidine (Spd) and spermine (Spm) elevated NO and H2O2 levels, enhanced nitrite reductase (NR), nitric oxide synthase (NOS)-like, and polyamine oxidase activities, and upregulated LeNR relative expression, but did not influence LeNOS1 expression. In contrast, putrescine (Put) treatment had no obvious impact. During the recovery period (25/15°C, 10 h), the above-mentioned parameters induced by the application of PAs were restored to their control levels. Seedlings pretreated with sodium nitroprusside (SNP, an NO donor) showed elevated Put and Spd levels throughout the treatment period, consistent with increased expression in leaves of genes encoding arginine decarboxylase (LeADC. LeADC1), ornithine decarboxylase (LeODC), and Spd synthase (LeSPDS) expressions in tomato leaves throughout the treatment period. Under chilling stress, the Put content increased first, followed by a rise in the Spd content. Exogenously applied SNP did not increase the expression of genes encoding S-adenosylmethionine decarboxylase (LeSAMDC) and Spm synthase (LeSPMS), consistent with the observation that Spm levels remained constant under chilling stress and during the recovery period. In contrast, exogenous Put significantly increased the ABA content and the 9-cis-epoxycarotenoid dioxygenase (LeNCED1) transcript level. Treatment with ABA could alleviate the electrolyte leakage (EL) induced by D-Arg (an inhibitor of Put). Taken together, it is concluded that, under chilling

  3. Abscisic Acid, High-Light, and Oxidative Stress Down-Regulate a Photosynthetic Gene via a Promoter Motif Not Involved in Phytochrome-Mediated Transcriptional Regulation

    Institute of Scientific and Technical Information of China (English)

    Roberto J. Staneloni; María José Rodriguez-Batiller; Jorge J. Casal

    2008-01-01

    In etiolated seedlings, light perceived by phytochrome promotes the expression of light-harvesting chlorophyll a/b protein of photosystem Ⅱ (Lhcb) genes. However, excess of photosynthetically active radiation can reduce Lhcb expression. Here, we investigate the convergence and divergence of phytochrome, high-light stress and abscisic acid (ABA)signaling, which could connect these processes. Etiolated Arabidopsis thaliana seedlings bearing an Lhcb promoter fused to a reporter were exposed to continuous far-red light to activate phytochrome and not photosynthesis, and treated with ABA. We identified a cis-acting region of the promoter required for down-regulation by ABA. This region contains a CCAC sequence recently found to be necessary for ABI4-binding to an Lhcb promoter. However, we did not find a G-box-binding core motif often associated with the ABI4-binding site in genes promoted by light and repressed by ABI4. Mutations involving this motif also impaired the responses to reduced water potential, the response to high photosynthetic light and the response to methyl viologen but not the response to low temperature or to Norflurazon. We propose a model based on current and previous findings, in which hydrogen peroxide produced in the chloroplasts under high light conditions interacts with the ABA signaling network to regulate Lhcb expression. Since the mutation that affects high-light and methyl viologen responses does not affect phytochrome-mediated responses, the regulation by retrograde and phytochrome signaling can finally be separated at the target promoter level.

  4. Uptake of (2-/sup 14/C)abscisic acid and distribution of /sup 14/C in apple embryos

    Energy Technology Data Exchange (ETDEWEB)

    Barthe, P.; Bulard, C.

    1981-01-01

    Pyrus malus L. var. Golden delicious embryos were incubated with (+-)-(2-/sup 14/C) abscisic acid (ABA). After incubations of various durations, the radioactivity was measured in whole embryos, cotyledons, and embryonic axes. With either 48-h or 16-d incubation periods, the uptake of (/sup 14/C) ABA depended upon the mode of culture used. The lowest values corresponded to the absorption by the embryonic axis, the highest to the absorption by the distal parts of the two cotyledons. The cotyledons accumulated the main part of the radioactivity under all conditions. Dormant and almost completely after-ripened embryos cultivated for 4 d showed no significant differences in the radioactivity uptake for identical modes of culture. There was a linear relationship between exogenous ABA concentrations (0.5 to 3.10/sup -5/ M) and ABA uptake for embryos cultivated for 4 d with the distal parts of the cotyledons immersed in the medium.

  5. Effects of Formulated Fertilizer Synergist on Abscisic Acid Accumulation, Proline Content and Photosynthetic Characteristics of Rice under Drought

    Institute of Scientific and Technical Information of China (English)

    WANG Shao-xian; XIA Shi-tou; PENG Ke-qin; KUANG Feng-chun; CAO Yong; XIAO Lang-tao

    2007-01-01

    To investigate the effects of formulated fertilizer synergist on the drought tolerance in rice, pot experiment was conducted to analyze the photosynthetic characteristics and the accumulation of abscisic acid (ABA) and proline in middle-season rice variety Peiliangyou 93. The synergist could improve the net photosynthetic rate, and coordination between the water loss and the CO2 absorption as well as reduce the harmful effect on photosynthetic process under drought conditions. Under drought, the ABA accumulated massively both in roots and leaves, while the ABA content in roots was far higher than that in leaves. The results indicate that synergist could increase the ABA accumulation, but reduce the proline accumulation in rice plant under drought.

  6. Sensitivity during the forced swim test is a key factor in evaluating the antidepressant effects of abscisic acid in mice.

    Science.gov (United States)

    Qi, Cong-Cong; Shu, Yu-Mian; Chen, Fang-Han; Ding, Yu-Qiang; Zhou, Jiang-Ning

    2016-03-01

    Abscisic acid (ABA), a crucial phytohormone, is distributed in the brains of mammals and has been shown to have antidepressant effects in the chronic unpredictable mild stress test. The forced swim test (FST) is another animal model that can be used to assess antidepressant-like behavior in rodents. Here, we report that the antidepressant effects of ABA are associated with sensitivities to the FST in mice. Based on mean immobility in the 5-min forced swim pre-test, ICR mice were divided into short immobility mice (SIM) and long immobility mice (LIM) substrains. FST was carried out 8 days after drug administration. Learned helplessness, as shown by increased immobility, was only observed in SIM substrain and could be prevented by an 8-day ABA treatment. Our results show that ABA has antidepressant effects in SIM substrain and suggest that mice with learned helplessness might be more suitable for screening potential antidepressant drugs.

  7. Structural Insights into Maize Viviparous14, a Key Enzyme in the Biosynthesis of the Phytohormone Abscisic Acid

    Energy Technology Data Exchange (ETDEWEB)

    Messing, Simon A.J.; Gabelli, Sandra B.; Echeverria, Ignacia; Vogel, Jonathan T.; Guan, Jiahn Chou; Tan, Bao Cai; Klee, Harry J.; McCarty, Donald R.; Amzel, L. Mario (JHU); (Florida)

    2011-09-06

    The key regulatory step in the biosynthesis of abscisic acid (ABA), a hormone central to the regulation of several important processes in plants, is the oxidative cleavage of the 11,12 double bond of a 9-cis-epoxycarotenoid. The enzyme viviparous14 (VP14) performs this cleavage in maize (Zea mays), making it a target for the rational design of novel chemical agents and genetic modifications that improve plant behavior through the modulation of ABA levels. The structure of VP14, determined to 3.2-{angstrom} resolution, provides both insight into the determinants of regio- and stereospecificity of this enzyme and suggests a possible mechanism for oxidative cleavage. Furthermore, mutagenesis of the distantly related CCD1 of maize shows how the VP14 structure represents a template for all plant carotenoid cleavage dioxygenases (CCDs). In addition, the structure suggests how VP14 associates with the membrane as a way of gaining access to its membrane soluble substrate.

  8. Structural Insights into Maize Viviparous14, a Key Enzyme in the Biosynthesis of the Phytohormone Abscisic Acid W

    Energy Technology Data Exchange (ETDEWEB)

    Messing, S.; Gabelli, S; Echeverria, I; Vogel, J; Guan, J; Tan, B; Klee, H; McCarty, D; Amzela, M

    2010-01-01

    The key regulatory step in the biosynthesis of abscisic acid (ABA), a hormone central to the regulation of several important processes in plants, is the oxidative cleavage of the 11,12 double bond of a 9-cis-epoxycarotenoid. The enzyme viviparous14 (VP14) performs this cleavage in maize (Zea mays), making it a target for the rational design of novel chemical agents and genetic modifications that improve plant behavior through the modulation of ABA levels. The structure of VP14, determined to 3.2-{angstrom} resolution, provides both insight into the determinants of regio- and stereospecificity of this enzyme and suggests a possible mechanism for oxidative cleavage. Furthermore, mutagenesis of the distantly related CCD1 of maize shows how the VP14 structure represents a template for all plant carotenoid cleavage dioxygenases (CCDs). In addition, the structure suggests how VP14 associates with the membrane as a way of gaining access to its membrane soluble substrate.

  9. Synthesis, structural characterization and effect on human granulocyte intracellular cAMP levels of abscisic acid analogs.

    Science.gov (United States)

    Bellotti, Marta; Salis, Annalisa; Grozio, Alessia; Damonte, Gianluca; Vigliarolo, Tiziana; Galatini, Andrea; Zocchi, Elena; Benatti, Umberto; Millo, Enrico

    2015-01-01

    The phytohormone abscisic acid (ABA), in addition to regulating physiological functions in plants, is also produced and released by several mammalian cell types, including human granulocytes, where it stimulates innate immune functions via an increase of the intracellular cAMP concentration ([cAMP]i). We synthesized several ABA analogs and evaluated the structure-activity relationship, by the systematical modification of selected regions of these analogs. The resulting molecules were tested for their ability to inhibit the ABA-induced increase of [cAMP]i in human granulocytes. The analogs with modified configurations at C-2' and C-3' abrogated the ABA-induced increase of the [cAMP]i and also inhibited several pro-inflammatory effects induced by exogenous ABA on granulocytes and monocytes. Accordingly, these analogs could be suitable as novel putative anti-inflammatory compounds.

  10. The p450 monooxygenase BcABA1 is essential for abscisic acid biosynthesis in Botrytis cinerea

    DEFF Research Database (Denmark)

    Siewers, V.; Smedsgaard, Jørn; Tudzynski, P.

    2004-01-01

    The phytopathogenic ascomycete Botrytis cinerea is known to produce abscisic acid (ABA), which is thought to be involved in host-pathogen interaction. Biochemical analyses had previously shown that, in contrast to higher plants, the fungal ABA biosynthesis probably does not proceed via carotenoids...... but involves direct cyclization of farnesyl diphosphate and subsequent oxidation steps. We present here evidence that this "direct" pathway is indeed the only one used by an ABA-overproducing strain of B. cinerea. Targeted inactivation of the gene bccpr1 encoding a cytochrome P450 oxidoreductase reduced...... the ABA production significantly, proving the involvement of P450 monooxygenases in the pathway. Expression analysis of 28 different putative P450 monooxygenase genes revealed two that were induced under ABA biosynthesis conditions. Targeted inactivation showed that one of these, bcaba1, is essential...

  11. The IBO germination quantitative trait locus encodes a phosphatase 2C-related variant with a nonsynonymous amino acid change that interferes with abscisic acid signaling.

    Science.gov (United States)

    Amiguet-Vercher, Amélia; Santuari, Luca; Gonzalez-Guzman, Miguel; Depuydt, Stephen; Rodriguez, Pedro L; Hardtke, Christian S

    2015-02-01

    Natural genetic variation is crucial for adaptability of plants to different environments. Seed dormancy prevents precocious germination in unsuitable conditions and is an adaptation to a major macro-environmental parameter, the seasonal variation in temperature and day length. Here we report the isolation of IBO, a quantitative trait locus (QTL) that governs c. 30% of germination rate variance in an Arabidopsis recombinant inbred line (RIL) population derived from the parental accessions Eilenburg-0 (Eil-0) and Loch Ness-0 (Lc-0). IBO encodes an uncharacterized phosphatase 2C-related protein, but neither the Eil-0 nor the Lc-0 variant, which differ in a single amino acid, have any appreciable phosphatase activity in in vitro assays. However, we found that the amino acid change in the Lc-0 variant of the IBO protein confers reduced germination rate. Moreover, unlike the Eil-0 variant of the protein, the Lc-0 variant can interfere with the activity of the phosphatase 2C ABSCISIC ACID INSENSITIVE 1 in vitro. This suggests that the Lc-0 variant possibly interferes with abscisic acid signaling, a notion that is supported by physiological assays. Thus, we isolated an example of a QTL allele with a nonsynonymous amino acid change that might mediate local adaptation of seed germination timing.

  12. 复苏植物旋蒴苣苔C2结构域小蛋白BhC2DP1参与植物对ABA的反应%A Small C2-domain Protein from the Resurrection Plant Boea hygrometrica Promotes Plant Responses to Abscisic Acid

    Institute of Scientific and Technical Information of China (English)

    张兰军; 姬飞腾; 王丽丽; 亓岽东; 朱燕; 邓馨

    2012-01-01

    为揭示植物抗旱的调控机理,对复苏植物旋蒴苣苔(Boea hygrometrica)的一个编码C2结构域小蛋白的基因BhC2DP1进行研究.Real-time PCR和ProBhC2DP1;GUS报告基因检测显示,该基因只在干旱早期和外源Ca2+处理0.5小时时受诱导表达;分别施加Ca2+螯合剂EGTA和逆境激素ABA均抑制该基因表达,但二者同时处理则显著诱导其表达,表明ABA对该基因转录水平的调控是Ca2+依赖型的.过表达BhC2DP1的拟南芥(Arabidopsis thaliana)对ABA的敏感性增强,EGTA处理可消除其与野生型的差异,表明Ca2+是BhC2DP1蛋白参与ABA反应所必需的.综上所述,ABA和Ca2+信号途径的精细调控可能是决定干旱诱导旋蒴苣苔中BhC2DP1基因表达时间、丰度和功能的重要机制.%Here we report on the cloning and characterization of BhC2DP1, a novel gene encoding a plant-specific small protein with a single C2 domain from the resurrection plant Boea hygrometrica. Phylogenic analysis of C2-domain proteins and sequence analysis revealed that BhC2DP1 belongs to the C2 elicitor responsive protein subfamily. Real-time PCR and histochemical study of a GUS reporter gene driven by the BhC2DP1 promoter in transgenic Arabidopsis showed BhC2DP1 transcripts increased at the early stage after dehydration and exposure to exogenous Ca2+ but decreased with prolonged treatment. Expression of BhC2DP1 was suppressed by abscisic acid (ABA) and Ca2+-chelating agent EGTA but was promoted by simultaneous exposure to ABA and EGTA, suggesting that the transcriptional regulation of BhC2DP1 by ABA is Ca2+ dependent. Constitutive overexpression of BMC2DP1 in Arabidopsis resulted in an ABA-hypersensitive phenotype, which was rescued by supplementing EGTA to growth media. Therefore, Ca2+ is necessary for the function of BhC2DP1 in responding to ABA. Our results provide new insights into the role of small C2-domain proteins and the fine-tuning regulation mechanism in response to drought stress.

  13. COPPER AMINE OXIDASE1 (CuA01)of Arabidopsis thaliana Contributes to Abscisic Acid-and Polyamine-Induced Nitric Oxide Biosynthesis and Abscisic Acid Signal Transduction

    Institute of Scientific and Technical Information of China (English)

    Rinukshi Wimalasekera; Corina Villar; Tahmina Begum; Günther F. E. Scherer

    2011-01-01

    Polyamines (PA), polyamine oxidases, copper amine oxidases, and nitric oxide (NO)play important roles in physiology and stress responses in plants. NO biosynthesis as a result of catabolism of PA by polyamine oxidases and copper amine oxidases may explain in part PA-mediated responses. Involvement of a copper amine oxidase gene, COPPER AMINE OXIDASE1 (CuA01), of Arabidopsis was tested for its role in stress responses using the knockouts cuaol.1 and cuaol-2. PA-induced and ABA-induced NO production investigated by fluorometry and fluorescence microscopy showed that the cuaol-1 and cuaol-2 are impaired in NO production, suggesting a function of CuAO1 in PA and ABA-mediated NO production. Furthermore, we found a PA-dependent increase in protein S-nitrosylation. The addition of PA and ABA also resulted in HO increases, cuaol-1 and cuaol-2 showed less sensitivity to exogenous ABA supplementation during ger-mination, seedling establishment, and root growth inhibition as compared to wild-type. In response to ABA treatment,expression levels of the stress-responsive genes RD29A and ADH1 were significantly lower in the knockouts. These obser-vations characterize cuaol-1 and cuaol-2 as ABA-insensitive mutants. Taken together, our findings extend the ABA signal transduction network to include CuAO1 as one potential contributor to enhanced NO production by ABA.

  14. Sustained exposure to abscisic acid enhances the colonization potential of the mutualist fungus Piriformospora indica on Arabidopsis thaliana roots.

    Science.gov (United States)

    Peskan-Berghöfer, Tatjana; Vilches-Barro, Amaya; Müller, Teresa M; Glawischnig, Erich; Reichelt, Michael; Gershenzon, Jonathan; Rausch, Thomas

    2015-11-01

    Root colonization by the beneficial fungus Piriformospora indica is controlled by plant innate immunity, but factors that channel this interaction into a mutualistic relationship are not known. We have explored the impact of abscisic acid (ABA) and osmotic stress on the P. indica interaction with Arabidopsis thaliana. The activation of plant innate immunity in roots was determined by measuring the concentration of the phytoalexin camalexin and expression of transcription factors regulating the biosynthesis of tryptophan-related defence metabolites. Furthermore, the impact of the fungus on the content of ABA, salicylic acid, jasmonic acid (JA) and JA-related metabolites was examined. We demonstrated that treatment with exogenous ABA or the ABA analogue pyrabactin increased fungal colonization efficiency without impairment of plant fitness. Concomitantly, ABA-deficient mutants of A. thaliana (aba1-6 and aba2-1) were less colonized, while plants exposed to moderate stress were more colonized than corresponding controls. Sustained exposure to ABA attenuated expression of transcription factors MYB51, MYB122 and WRKY33 in roots upon P. indica challenge or chitin treatment, and prevented an increase in camalexin content. The results indicate that ABA can strengthen the interaction with P. indica as a consequence of its impact on plant innate immunity. Consequently, ABA will be relevant for the establishment and outcome of the symbiosis under stress conditions.

  15. P-HYDROXYPHENYLPYRUVATE DIOXYGENASE from Medicago sativa is involved in vitamin E biosynthesis and abscisic acid-mediated seed germination

    Science.gov (United States)

    Jiang, Jishan; Chen, Zhihong; Ban, Liping; Wu, Yudi; Huang, Jianping; Chu, Jinfang; Fang, Shuang; Wang, Zan; Gao, Hongwen; Wang, Xuemin

    2017-01-01

    P-HYDROXYPHENYLPYRUVATE DIOXYGENASE (HPPD) is the first committed enzyme involved in the biosynthesis of vitamin E, and is characterized by catalyzing the conversion of p-hydroxyphenyl pyruvate (HPP) to homogentisic acid (HGA). Here, an HPPD gene was cloned from Medicago sativa L. and designated MsHPPD, which was expressed at high levels in alfalfa leaves. PEG 6000 (polyethylene glycol), NaCl, abscisic acid and salicylic acid were shown to significantly induce MsHPPD expression, especially in the cotyledons and root tissues. Overexpression of MsHPPD was found to significantly increase the level of β-tocotrienol and the total vitamin E content in Arabidopsis seeds. Furthermore, these transgenic Arabidopsis seeds exhibited an accelerated germination time, compared with wild-type seeds under normal conditions, as well as under NaCl and ABA treatments. Meanwhile, the expression level of several genes associated with ABA biosynthesis (NCED3, NCED5 and NCED9) and the ABA signaling pathway (RAB18, ABI3 and ABI5) were significantly down-regulated in MsHPPD-overexpressing transgenic lines, as well as the total free ABA content. Taken together, these results demonstrate that MsHPPD functions not only in the vitamin E biosynthetic pathway, but also plays a critical role in seed germination via affecting ABA biosynthesis and signaling. PMID:28084442

  16. Overexpression of EsMcsu1 from the halophytic plant Eutrema salsugineum promotes abscisic acid biosynthesis and increases drought resistance in alfalfa (Medicago sativa L.).

    Science.gov (United States)

    Zhou, C; Ma, Z Y; Zhu, L; Guo, J S; Zhu, J; Wang, J F

    2015-12-17

    The stress phytohormone abscisic acid (ABA) plays pivotal roles in plants' adaptive responses to adverse environments. Molybdenum cofactor sulfurases influence aldehyde oxidase activity and ABA biosynthesis. In this study, we isolated a novel EsMcsu1 gene encoding a molybdenum cofactor sulfurase from Eutrema salsugineum. EsMcus1 transcriptional patterns varied between organs, and its expression was significantly upregulated by abiotic stress or ABA treatment. Alfalfa plants that overexpressed EsMcsu1 had a higher ABA content than wild-type (WT) plants under drought stress conditions. Furthermore, levels of reactive oxygen species (ROS), ion leakage, and malondialdehyde were lower in the transgenic plants than in the WT plants after drought treatment, suggesting that the transgenic plants experienced less ROS-mediated damage. However, the expression of several stress-responsive genes, antioxidant enzyme activity, and osmolyte (proline and total soluble sugar) levels in the transgenic plants were higher than those in the WT plants after drought treatment. Therefore, EsMcsu1 overexpression improved drought tolerance in alfalfa plants by activating a series of ABA-mediated stress responses.

  17. An A20/AN1-type zinc finger protein modulates gibberellins and abscisic acid contents and increases sensitivity to abiotic stress in rice (Oryza sativa).

    Science.gov (United States)

    Zhang, Ye; Lan, Hongxia; Shao, Qiaolin; Wang, Ruqin; Chen, Hui; Tang, Haijuan; Zhang, Hongsheng; Huang, Ji

    2016-01-01

    The plant hormones gibberellins (GA) and abscisic acid (ABA) play important roles in plant development and stress responses. Here we report a novel A20/AN1-type zinc finger protein ZFP185 involved in GA and ABA signaling in the regulation of growth and stress response. ZFP185 was constitutively expressed in various rice tissues. Overexpression of ZFP185 in rice results in a semi-dwarfism phenotype, reduced cell size, and the decrease of endogenous GA3 content. By contrast, higher GA3 content was observed in RNAi plants. The application of exogenous GA3 can fully rescue the semi-dwarfism phenotype of ZFP185 overexpressing plants, suggesting the negative role of ZFP185 in GA biosynthesis. Besides GA, overexpression of ZFP185 decreased ABA content and expression of several ABA biosynthesis-related genes. Moreover, it was found that ZFP185, unlike previously known A20/AN1-type zinc finger genes, increases sensitivity to drought, cold, and salt stresses, implying the negative role of ZFP185 in stress tolerance. ZFP185 was localized in the cytoplasm and lacked transcriptional activation potential. Our study suggests that ZFP185 regulates plant growth and stress responses by affecting GA and ABA biosynthesis in rice.

  18. Effect of abscisic acid on biochemical constituents, enzymatic and non enzymatic antioxidant status of lettuce (Lactuca sativa L. under varied irrigation regimes

    Directory of Open Access Journals (Sweden)

    Mohamed A. Al Muhairi

    2015-12-01

    Full Text Available Economically important vegetable crop lettuce (Lactuca sativa L. of family Asteraceae was selected for the present investigation. It is being cultivated in UAE due to its commercial importance. In lettuce cultivation, the major problem is the requirement of large quantities of irrigation water. The present study was aimed to reduce the water consumption of lettuce cultivation; for that, a varied irrigation regime was used with the application of abscisic acid (ABA. The parameters studied were biochemical constituents, antioxidant potential and antioxidant enzymes’ activities in lettuce plants under drought stress and its response to ABA under stress. Drought stress caused an increase in the biochemical constituents like proline and amino acid contents when compared with control and also increased under individual ABA treatments and treatments under drought stress. The non-enzymatic antioxidant molecules like ascorbate and α-tocopherol showed significant increase under drought condition in lettuce. ABA slightly reduced these contents. The antioxidant enzymes like superoxide dismutase, catalase and peroxidase showed significant increase under drought condition and ABA caused significant enhancement in these antioxidant enzymes under drought stress and also in unstressed conditions, thereby protecting the plants from the deleterious effects of drought stress. From the results of this investigation, it can be concluded that ABA in 10 mg g−1 can be used as a potential tool to minimise the drought stress effects in lettuce cultivation.

  19. Leaf Abscission Induced by Ethylene in Water-Stressed Intact Seedlings of Cleopatra Mandarin Requires Previous Abscisic Acid Accumulation in Roots.

    Science.gov (United States)

    Gomez-Cadenas, A.; Tadeo, F. R.; Talon, M.; Primo-Millo, E.

    1996-09-01

    The involvement of abscisic acid (ABA) in the process of leaf abscission induced by 1-aminocyclopropane-1-carboxylic acid (ACC) transported from roots to shoots in Cleopatra mandarin (Citrus reshni Hort. ex Tan.) seedlings grown under water stress was studied using norflurazon (NF). Water stress induced both ABA (24-fold) and ACC (16-fold) accumulation in roots and arrested xylem flow. Leaf bulk ABA also increased (8-fold), although leaf abscission did not occur. Shortly after rehydration, root ABA and ACC returned to their prestress levels, whereas sharp and transitory increases of ACC (17-fold) and ethylene (10-fold) in leaves and high percentages of abscission (up to 47%) were observed. NF suppressed the ABA and ACC accumulation induced by water stress in roots and the sharp increases of ACC and ethylene observed after rewatering in leaves. NF also reduced leaf abscission (7-10%). These results indicate that water stress induces root ABA accumulation and that this is required for the process of leaf abscission to occur. It was also shown that exogenous ABA increases ACC levels in roots but not in leaves. Collectively, the data suggest that ABA, the primary sensitive signal to water stress, modulates the levels of ethylene, which is the hormonal activator of leaf abscission. This assumption implies that root ACC levels are correlated with root ABA amounts in a dependent way, which eventually links water status to an adequate, protective response such as leaf abscission.

  20. Effects of Exterior Abscisic Acid on Calcium Distribution of Mesophyll Cells and Calcium Concentration of Guard Cells in Maize Seedlings

    Institute of Scientific and Technical Information of China (English)

    GUO Xiu-lin; MA Yuan-yuan; LIU Zi-hui; LIU Bin-hui

    2008-01-01

    In this study, the direct effects of exterior abscisic acid (ABA) on both calcium distribution of mesophyll cells and cytosolic calcium concentration of guard cells were examined. The distribution of Ca2+ localization were observed with calcium antimonate precipitate-electromicroscopic-cyto-chemical methods after treated with ABA and pretreated with ethylene glycol-bis-(2-aminoethylether)-N,N,N',N'-tetraacetic acid (EGTA), verapamil (Vp), and trifluoperazine (TFP). The laser scanning confocal microscopy was used to measure the cytosolic calcium concentrations of guard cells under different treatments. The results showed that the cytosolic Ca2+ concentration of mesophyll cells was induced to increase by ABA, but to decrease in both outside cell and the vacuoles within 10 min after treatments. The cytosolic calcium concentration of guard cells was increased gradually with the lag in treatment time. However, both EGTA and TFP could inverse those effects, indicating that the increase of cytosolic calcium induced by exterior ABA was mainly caused by calcium influx. The results also showed that calmodulin could influence both the calcium distribution of mesophyll cells and calcium concentration of guard cells. It shows that calmodulin participates in the process of ABA signal transduction, but the mechanism is not known as yet. The changes both calcium distribution of mesophyll cells and calcium concentration of guard cells further proved that the variations of cytosolic Ca2+ concentration induced by ABA were involved in the stomatal movements of maize seedlings.

  1. Abscisic acid promotes accumulation of toxin ODAP in relation to free spermine level in grass pea seedlings (Lathyrus sativus L.).

    Science.gov (United States)

    Xiong, You-Cai; Xing, Geng-Mei; Li, Feng-Min; Wang, Shao-Ming; Fan, Xian-Wei; Li, Zhi-Xiao; Wang, Ya-Fu

    2006-01-01

    Interrelationship among abscisic acid (ABA) content, accumulation of free polyamines and biosynthesis of beta-N-oxalyl-l-alpha,beta-diaminopropionic acid (ODAP) was studied in grass pea (Lathyrus sativus L.) seedlings under drought stress induced by 10% polyethylene glycol (PEG6000). Increase of ABA content occurred prior to that of ODAP and polyamine contents, and was found significantly positive correlation between ABA content and ODAP content. Addition of exogenous ABA increased ODAP content in leaves. On the other hand, pretreatment with alpha-difluoromethylarginine (DFMA), a polyamine biosynthesis inhibitor, significantly suppressed the accumulation of free putrescine (Put), free spermidine (Spd) and free spermine (Spm), which in turn inhibited biosynthesis of ODAP in well-watered leaves. Meanwhile, addition of exogenous Put alleviated DFMA-induced inhibition on the biosynthesis of Put and Spd, but did not affect the biosynthesis of Spm and ODAP in well-watered leaves. Same result was also achieved in drought-stressed leaves. Increasing accumulation of ODAP was significantly correlated with increasing Spm content (R=0.7957**) but not with that of Spd and Put. Therefore, it can be argued that ABA stimulated the biosynthesis of ODAP simultaneously with increasing the level of free Spm under drought stress condition.

  2. Expression of genes associated with the biosynthetic pathways of abscisic acid, gibberellin, and ethylene during the germination of lettuce seeds.

    Science.gov (United States)

    Clemente, A C S; Guimarães, R M; Martins, D C; Gomes, L A A; Caixeta, F; Reis, R G E; Rosa, S D V F

    2015-01-01

    Seed germination and dormancy are complex phenomena that are controlled by many genes and environmental factors. Such genes are indicated by phytohormones that interact with each other, and may cause dormancy or promote seed germination. The objective of this study was to investigate gene expression associated with the biosynthetic pathways of abscisic acid (ABA), gibberellic acid (GA), and ethylene (ET) in dormant and germinated lettuce seeds. The expressions of LsNCED, LsGA3ox1, and ACO-B were evaluated in germinating and dormant seeds from the cultivars Everglades, Babá de Verão, Verônica, Salinas, Colorado, and Regina 71. The expressions of LsNCED, LsGA3ox1, and ACO-B were related to the biosynthesis of ABA, GA, and ET, respectively; therefore, the presence of these substances depends on genotype. LsNCED expression only occurred in dormant seeds, and was connected to dormancy. LsGA3ox1expression only occurred in germinated seeds, and was connected to germination. The ACO-B gene was involved in ET biosynthesis, and was expressed differently in germinated and dormant seeds, depending on the genotype, indicating different functions for different characteristics. Furthermore, sensitivity to phytohormones appeared to be more important than the expression levels of LsNCED, LsGA3ox1, or ACO-B.

  3. Abscisic acid prevents the coalescence of protein storage vacuoles by upregulating expression of a tonoplast intrinsic protein gene in barley aleurone.

    Science.gov (United States)

    Lee, Sung-eun; Yim, Hui-kyung; Lim, Mi-na; Yoon, In sun; Kim, Jeong hoe; Hwang, Yong-sic

    2015-03-01

    Tonoplast intrinsic proteins (TIPs) are integral membrane proteins that are known to function in plants as aquaporins. Here, we propose another role for TIPs during the fusion of protein storage vacuoles (PSVs) in aleurone cells, a process that is promoted by gibberellic acid (GA) and prevented by abscisic acid (ABA). Studies of the expression of barley (Hordeum vulgare) TIP genes (HvTIP) showed that GA specifically decreased the abundance of HvTIP1;2 and HvTIP3;1 transcripts, while ABA strongly increased expression of HvTIP3;1. Increased or decreased expression of HvTIP3;1 interfered with the hormonal effects on vacuolation in aleurone protoplasts. HvTIP3;1 gain-of-function experiments delayed GA-induced vacuolation, whereas HvTIP3;1 loss-of-function experiments promoted vacuolation in ABA-treated aleurone cells. These results indicate that TIP plays a key role in preventing the coalescence of small PSVs in aleurone cells. Hormonal regulation of the HvTIP3;1 promoter is similar to the regulation of the endogenous gene, indicating that induction of the transcription of HvTIP3;1 by ABA is a critical factor in the prevention of PSV coalescence in response to ABA. Promoter analysis using deletions and site-directed mutagenesis of sequences identified three cis-acting elements that are responsible for ABA responsiveness in the HvTIP3;1 promoter. Promoter analysis also showed that ABA responsiveness of the HvTIP3;1 promoter is likely to occur via a unique regulatory system distinct from that involving the ABA-response promoter complexes.

  4. Plant, cell, and molecular mechanisms of abscisic-acid regulation of stomatal apertures. In vivo phosphorylation of phosphoenolpyruvate carboxylase in guard cells of Vicia faba L. is enhanced by fusicoccin and suppressed by abscisic acid

    Energy Technology Data Exchange (ETDEWEB)

    Du, Z.; Aghoram, K.; Outlaw, W.H. Jr.

    1996-12-31

    Plants regulate water loss and CO{sub 2} gain by modulating the aperture sizes of stomata that penetrate the epidermis. Aperture size itself is increased by osmolyte accumulation and consequent turgor increase in the pair of guard cells that flank each stoma. Guard-cell phosphoenolpyruvate carboxylase, which catalyzes the regulated step leading to malate synthesis, is crucial for charge and pH maintenance during osmolyte accumulation. Regulation of this cytosolic enzyme by effectors is well documented, but additional regulation by posttranslational modification is predicted by the alteration of PEPC kinetics during stomatal opening. In this study, the authors have investigated whether this alteration is associated with the phosphorylation status of this enzyme. Using sonicated epidermal peels (isolated guard cells) pre-loaded with {sub 32}PO{sub 4}, the authors induced stomatal opening and guard-cell malate accumulation by incubation with 5 {micro}M fusicoccin (FC). In corroboratory experiments, guard cells were incubated with 5 {micro}M fusicoccin (FC). In corroboratory experiments, guard cells were incubated with the FC antagonist, 10 {micro}M abscisic acid (ABA). The phosphorylation status of PEPC was assessed by immunoprecipitation, electrophoresis, immunoblotting, and autoradiography. PEPC was phosphorylated when stomata were stimulated to open, and phosphorylation was lessened by incubation with ABA.

  5. In vivo Characterization of the Effects of Abscisic Acid and Drying Protocols Associated with the Acquisition of Desiccation Tolerance in Alfalfa (Medicago sativa L.) Somatic Embryos

    OpenAIRE

    SREEDHAR, LEKHA; Wolkers, Willem F.; Hoekstra, Folkert A.; BEWLEY, J. DEREK

    2002-01-01

    Although somatic embryos of alfalfa (Medicago sativa L.) had acquired some tolerance to desiccation at the cotyledonary stage of development (22 d after plating), additional culturing in 20 μm abscisic acid (ABA) for 8 d induced greater desiccation tolerance, as determined by increased germination. Compared with fast drying, slow drying of the ABA‐treated embryos improved desiccation tolerance. However, slow drying of non‐ABA‐treated embryos led to the complete loss of germination capacity, w...

  6. Abscisic Acid Regulation of Root Hydraulic Conductivity and Aquaporin Gene Expression Is Crucial to the Plant Shoot Growth Enhancement Caused by Rhizosphere Humic Acids.

    Science.gov (United States)

    Olaetxea, Maite; Mora, Verónica; Bacaicoa, Eva; Garnica, María; Fuentes, Marta; Casanova, Esther; Zamarreño, Angel M; Iriarte, Juan C; Etayo, David; Ederra, Iñigo; Gonzalo, Ramón; Baigorri, Roberto; García-Mina, Jose M

    2015-12-01

    The physiological and metabolic mechanisms behind the humic acid-mediated plant growth enhancement are discussed in detail. Experiments using cucumber (Cucumis sativus) plants show that the shoot growth enhancement caused by a structurally well-characterized humic acid with sedimentary origin is functionally associated with significant increases in abscisic acid (ABA) root concentration and root hydraulic conductivity. Complementary experiments involving a blocking agent of cell wall pores and water root transport (polyethylenglycol) show that increases in root hydraulic conductivity are essential in the shoot growth-promoting action of the model humic acid. Further experiments involving an inhibitor of ABA biosynthesis in root and shoot (fluridone) show that the humic acid-mediated enhancement of both root hydraulic conductivity and shoot growth depended on ABA signaling pathways. These experiments also show that a significant increase in the gene expression of the main root plasma membrane aquaporins is associated with the increase of root hydraulic conductivity caused by the model humic acid. Finally, experimental data suggest that all of these actions of model humic acid on root functionality, which are linked to its beneficial action on plant shoot growth, are likely related to the conformational structure of humic acid in solution and its interaction with the cell wall at the root surface.

  7. Activity, but not Expression, of Soluble and Cell Wall-Bound Acid Invertases Is Induced by Abscisic Acid in Developing Apple Fruit

    Institute of Scientific and Technical Information of China (English)

    Qiu-Hong Pan; Xiang-Chun Yu; Na Zhang; Xun Zou; Chang-Cao Peng; Xiu-Ling Wang; Ke-Qin Zou; Da-Peng Zhang

    2006-01-01

    The present experiment, involving both the in vivo injection of abscisic acid (ABA) into apple (Malus domestica Brohk.) fruits and the in vivo incubation of fruit tissues in ABA-containing medium, revealed that ABA activates both soluble and cell wall-bound acid invertases. Immunoblotting and enzyme-linked immunosorbent assays showed that this ABA-induced acid invertase activation is independent of the amount of enzyme present. The acid invertase activation induced by ABA is dependent on medium pH, time course, ABA dose, living tissue and developmental stage. Two isomers of cis-(+)-ABA, (-)-ABA and transABA, had no effect on acid invertases, showing that ABA-induced acid invertase activation is specific to physiologically active cis-(+)ABA. Protein kinase inhibitors K252a and H7 as well as acid phosphatase increased the ABA-induced effects. These data indicate that ABA specifically activates both soluble and cell wall-bound acid invertases by a posttranslational mechanism probably involving reversible protein phosphorylation, and this may be one of the mechanisms by which ABA is involved in regulating fruit development.

  8. Abscisic acid as an internal integrator of multiple physiological processes modulates leaf senescence onset in Arabidopsis thaliana

    Directory of Open Access Journals (Sweden)

    Yuwei eSong

    2016-02-01

    Full Text Available Many studies have shown that exogenous abscisic acid (ABA promotes leaf abscission and senescence. However, owing to a lack of genetic evidence, ABA function in plant senescence has not been clearly defined. Here, two-leaf early-senescence mutants (eas that were screened by chlorophyll fluorescence imaging and named eas1-1 and eas1-2 showed high photosynthetic capacity in the early stage of plant growth compared with the wild type. Gene mapping showed that eas1-1 and eas1-2 are two novel ABA2 allelic mutants. Under unstressed conditions, the eas1 mutations caused plant dwarf, early germination, larger stomatal apertures, and early leaf senescence compared with those of the wild type. Flow cytometry assays showed that the cell apoptosis rate in eas1 mutant leaves was higher than that of the wild type after day 30. A significant increase in the transcript levels of several senescence-associated genes, especially SAG12, was observed in eas1 mutant plants in the early stage of plant growth. More importantly, ABA-activated calcium channel activity in plasma membrane and induced the increase of cytoplasmic calcium concentration in guard cells are suppressed due to the mutation of EAS1. In contrast, the eas1 mutants lost chlorophyll and ion leakage significant faster than in the wild type under treatment with calcium channel blocker. Hence, our results indicate that endogenous ABA level is an important factor controlling the onset of leaf senescence through Ca2+ signaling.

  9. Implication of abscisic acid on ripening and quality in sweet cherries: differential effects during pre- and postharvest

    Directory of Open Access Journals (Sweden)

    Verónica eTijero

    2016-05-01

    Full Text Available Sweet cherry, a non-climacteric fruit, is usually cold-stored during postharvest to prevent over-ripening. The aim of the study was to evaluate the role of abscisic acid (ABA on fruit growth and ripening of this fruit, considering as well its putative implication in over-ripening and effects on quality. We measured the endogenous concentrations of ABA during the ripening of sweet cherries (Prunus avium L. var. Prime Giant collected from orchard trees and in cherries exposed to 4ºC and 23ºC during 10d of postharvest. Furthermore, we examined to what extent endogenous ABA concentrations were related to quality parameters, such as fruit biomass, anthocyanin accumulation and levels of vitamins C and E. Endogenous concentrations of ABA in fruits increased progressively during fruit growth and ripening on the tree, to decrease later during postharvest at 23ºC. Cold treatment, however, increased ABA levels and led to an inhibition of over-ripening. Furthermore, ABA levels positively correlated with anthocyanin and vitamin E levels during preharvest, but not during postharvest. We conclude that ABA plays a major role in sweet cherry development, stimulating its ripening process and positively influencing quality parameters during preharvest. The possible influence of ABA preventing over-ripening in cold-stored sweet cherries is also discussed.

  10. Implication of Abscisic Acid on Ripening and Quality in Sweet Cherries: Differential Effects during Pre- and Post-harvest

    Science.gov (United States)

    Tijero, Verónica; Teribia, Natalia; Muñoz, Paula; Munné-Bosch, Sergi

    2016-01-01

    Sweet cherry, a non-climacteric fruit, is usually cold-stored during post-harvest to prevent over-ripening. The aim of the study was to evaluate the role of abscisic acid (ABA) on fruit growth and ripening of this fruit, considering as well its putative implication in over-ripening and effects on quality. We measured the endogenous concentrations of ABA during the ripening of sweet cherries (Prunus avium L. var. Prime Giant) collected from orchard trees and in cherries exposed to 4°C and 23°C during 10 days of post-harvest. Furthermore, we examined to what extent endogenous ABA concentrations were related to quality parameters, such as fruit biomass, anthocyanin accumulation and levels of vitamins C and E. Endogenous concentrations of ABA in fruits increased progressively during fruit growth and ripening on the tree, to decrease later during post-harvest at 23°C. Cold treatment, however, increased ABA levels and led to an inhibition of over-ripening. Furthermore, ABA levels positively correlated with anthocyanin and vitamin E levels during pre-harvest, but not during post-harvest. We conclude that ABA plays a major role in sweet cherry development, stimulating its ripening process and positively influencing quality parameters during pre-harvest. The possible influence of ABA preventing over-ripening in cold-stored sweet cherries is also discussed. PMID:27200070

  11. Graviresponsiveness and abscisic-acid content of roots of carotenoid-deficient mutants of Zea mays L

    Science.gov (United States)

    Moore, R.; Smith, J. D.

    1985-01-01

    The abscisic-acid (ABA) content of roots of the carotenoid-deficient w-3, vp-5, and vp-7 mutants of Z. mays was analyzed using gas chromatography-mass spectrometry with an analysis sensitivity of 6 ng ABA g-1 fresh weight (FW). Roots of normal seedlings of the same lines were characterized by the following amounts of ABA (as ng ABA g-1 FW, +/- standard deviation): w-3, 279 +/- 43; vp-5, 237 +/- 26; vp-7, 338 +/- 61. We did not detect any ABA in roots of any of the mutants. Thus, the lack of carotenoids in these mutants correlated positively with the apparent absence of ABA. Primary roots of normal and mutant seedlings were positively gravitropic, with no significant differences in the curvatures of roots of normal as compared with mutant seedlings. These results indicate that ABA 1) is synthesized in maize roots via the carotenoid pathway, and 2) is not necessary for positive gravitropism by primary roots of Z. mays.

  12. OsHK3 is a crucial regulator of abscisic acid signaling involved in antioxidant defense in rice

    Institute of Scientific and Technical Information of China (English)

    Feng Wen; Tingting Qin; Yao Wang; Wen Dong; Aying Zhang; Mingpu Tan; Mingyi Jiang

    2015-01-01

    In this study, the role of the rice (Oryza sativa L.) histidine kinase OsHK3 in abscisic acid (ABA)‐induced antioxi-dant defense was investigated. Treatments with ABA, H2O2, and polyethylene glycol (PEG) induced the expression of OsHK3 in rice leaves, and H2O2 is required for ABA‐induced increase in the expression of OsHK3 under water stress. Subcel ular localization analysis showed that OsHK3 is located in the cytoplasm and the plasma membrane. The transient expres-sion analysis and the transient RNA interference test in rice protoplasts showed that OsHK3 is required for ABA‐induced upregulation in the expression of antioxidant enzymes genes and the activities of antioxidant enzymes. Further analysis showed that OsHK3 functions upstream of the calcium/calmodulin‐dependent protein kinase OsDMI3 and the mito-gen‐activated protein kinase OsMPK1 to regulate the activities of antioxidant enzymes in ABA signaling. Moreover, OsHK3 was also shown to regulate the expression of nicotinamide adenine dinucleotide phosphate oxidase genes, OsrbohB and OsrbohE, and the production of H2O2 in ABA signaling. Our data indicate that OsHK3 play an important role in the regulation of ABA‐induced antioxidant defense and in the feedback regula-tion of H2O2 production in ABA signaling.

  13. Evidence for a universal pathway of abscisic acid biosynthesis in higher plants from sup 18 O incorporation patterns

    Energy Technology Data Exchange (ETDEWEB)

    Zeevaart, J.A.D.; Heath, T.G.; Gage, D.A. (Michigan State University, East Lansing (USA))

    1989-12-01

    Previous labeling studies of abscisic acid (ABA) with {sup 18}O{sub 2} have been mainly conducted with water-stressed leaves. In this study, {sup 18}O incorporation into ABA of stressed leaves of various species was compared with {sup 18}O labeling of ABA of turgid leaves and of fruit tissue in different stages of ripening. In stressed leaves of all six species investigated, avocado (Persea americana), barley (Hordeum vulgare), bean (Phaseolus vulgaris), cocklebur (Xanthium strumarium), spinach (Spinacia oleracea), and tobacco (Nicotiana tabacum), {sup 18}O was most abundant in the carboxyl group, whereas incorporation of a second and third {sup 18}O in the oxygen atoms on the ring of ABA was much less prominent after 24 h in {sup 18}O{sub 2}. ABA from turgid bean leaves showed significant {sup 18}O incorporation, again with highest {sup 18}O enrichment in the carboxyl group. On the basis of {sup 18}O-labeling patterns observed in ABA from different tissues it is concluded that, despite variations in precusor pool sizes and intermediate turnover rates, there is a universal pathway of ABA biosynthesis in higher plants which involves cleavage of a larger precursor molecule, presumably an oxygenated carotenoid.

  14. Gene Overexpression and RNA Silencing Tools for the Genetic Manipulation of the S-(+-Abscisic Acid Producing Ascomycete Botrytis cinerea

    Directory of Open Access Journals (Sweden)

    Zhong-Tao Ding

    2015-05-01

    Full Text Available The phytopathogenic ascomycete Botrytis cinerea produces several secondary metabolites that have biotechnical significance and has been particularly used for S-(+-abscisic acid production at the industrial scale. To manipulate the expression levels of specific secondary metabolite biosynthetic genes of B. cinerea with Agrobacterium tumefaciens-mediated transformation system, two expression vectors (pCBh1 and pCBg1 with different selection markers and one RNA silencing vector, pCBSilent1, were developed with the In-Fusion assembly method. Both expression vectors were highly effective in constitutively expressing eGFP, and pCBSilent1 effectively silenced the eGFP gene in B. cinerea. Bcaba4, a gene suggested to participate in ABA biosynthesis in B. cinerea, was then targeted for gene overexpression and RNA silencing with these reverse genetic tools. The overexpression of bcaba4 dramatically induced ABA formation in the B. cinerea wild type strain Bc-6, and the gene silencing of bcaba4 significantly reduced ABA-production in an ABA-producing B. cinerea strain.

  15. The role of abscisic acid and low temperature in chickpea (Cicer arietinum) cold tolerance. II. Effects on plasma membrane structure and function.

    Science.gov (United States)

    Bakht, Jehan; Bano, Asghari; Dominy, Peter

    2006-01-01

    The frost hardiness of many plants such as chickpea can be increased by exposure to low non-freezing temperatures and/or the application of abscisic acid (ABA), a process known as frost acclimation. Experiments were conducted to study the response over a 14 d period of enriched plasma membrane fractions isolated from chickpea plants exposed to low temperature and sprayed with exogenous ABA. Measurement of the temperatures inducing 50% foliar cell death (LT50), and subsequent statistical analysis suggest that, like many plants, exposure to low temperatures (5/-2 degrees C; day/night) induces a significant level (P chickpea when compared with control plants (20/7 degrees C; day/night). Spraying plants with exogenous ABA also increased frost tolerance (P chickpea plants to low temperatures increased the DBI by 15% at day 4 and 19% at day 14 when compared with untreated control plants. Application of ABA alone did not increase the DBI by more than 6% at any time; the effects of both treatments applied together was more than additive, inducing a DBI increase of 27% at day 14 when compared with controls. There was a good correlation (P properties of the plasma membrane other than fluidity are involved in frost acclimation in chickpea.

  16. Nitric oxide suppresses the inhibitory effect of abscisic acid on seed germination by S-nitrosylation of SnRK2 proteins.

    Science.gov (United States)

    Wang, Pengcheng; Zhu, Jian-Kang; Lang, Zhaobo

    2015-01-01

    Nitric oxide (NO) plays important roles in plant development, and biotic and abiotic stress responses. In a recent study, we showed that endogenous NO negatively regulates abscisic acid (ABA) signaling in guard cells by inhibiting sucrose nonfermenting 1 (SNF1)-related protein kinase 2.6 (SnRK2.6)/open stomata 1(OST1) through S-nitrosylation. Application of NO breaks seed dormancy and alleviates the inhibitory effect of ABA on seed germination and early seedling growth, but it is unclear how NO functions at the stages of seed germination and early seedling development. Here, we show that like SnRK2.6, SnRK2.2 can be inactivated by S-nitrosoglutathione (GSNO) treatment through S-nitrosylation. SnRK2.2 and the closely related SnRK2.3 are known to play redundant roles in ABA inhibition of seed germination in Arabidopsis. We found that treatment with the NO donor SNP phenocopies the snrk2.2snrk2.3 double mutant in conferring ABA insensitivity at the stages of seed germination and early seedling growth. Our results suggest that NO negatively regulates ABA signaling in germination and early seedling growth through S-nitrosylation of SnRK2.2 and SnRK2.3.

  17. The Detection of Abscisic Acid in Arabidopsis Protoplasts by LC-MS%LC-MS法测定拟南芥原生质体脱落酸的研究

    Institute of Scientific and Technical Information of China (English)

    郭磊; Mohammed Humayun KABIR; 童建华; 黄志刚; 萧浪涛

    2012-01-01

    Abscisic acid plays a very important role in many plant developmental processes and stress response systems. Accurate detection of abscisic acid content on agricultural production and scientific research has important significance. We analyzed the abscisic acid content of protoplasts isolated from soil cultivated Arabidopsis leaves and hydroponically cultivated roots by using high - performance liquid chromatography with mass spectrometry. The results showed that there was a good linear relation between the content of abscisic acid and protoplasts number and the correlation coefficients were 0. 992 3, 0. 993 1 for Arabidopsis leaves and roots protoplasts, respectively. Detection limit for ABA content was 1.07 ng/mL, and the minimum Arabidopsis leaves and roots protoplasts numbers were 30 000 and 20 000, respectively. The material of this study were protoplasts which can avoid the interference of the complex chemicals from intercellular substance as well as improve sensitivity and the precision of phytohormones determination. It can also improve the classical phytohormones determination technologyies.%利用高效液相色谱与质谱联用法(LC-MS法)对从土培拟南芥叶片和水培拟南芥根系中分离的原生质体进行脱落酸含量分析.结果表明,所测原生质体的脱落酸含量与原生质体数目之间具有较好的线性关系,相关系数分别为0.992 3和0.993 1.脱落酸含量的检测下限为1.07 ng/mL,土培拟南芥叶片和水培拟南芥根系原生质体检测下限分别为3万个和2万个.该研究以原生质体为材料,避免了细胞间隙中的复杂化学成干扰,提高了植物激素测定的灵敏度和精度,完善了经典的植物激素测定技术.

  18. Abscisic acid enhances tolerance of wheat seedlings to drought and regulates transcript levels of genes encoding ascorbate-glutathione biosynthesis

    Directory of Open Access Journals (Sweden)

    Wei eLiting

    2015-06-01

    Full Text Available Glutathione (GSH and ascorbate (ASA are associated with the abscisic acid (ABA-induced abiotic tolerance in higher plant, however, its molecular mechanism remains obscure. In this study, exogenous application (10 μM of ABA significantly increased the tolerance of seedlings of common wheat (Triticum aestivum L. suffering from 5 days of 15% polyethylene glycol (PEG-stimulated drought stress, as demonstrated by increased shoot lengths and shoot and root dry weights, while showing decreased contents of hydrogen peroxide (H2O2 and malondialdehyde (MDA. Under drought stress conditions, ABA markedly increased contents of GSH and ASA in both leaves and roots of ABA-treated plants. Temporal and spatial expression patterns of eight genes encoding ASA and GSH synthesis-related enzymes were measured using quantitative real-time reverse transcription polymerase chain reaction (qPCR. The results showed that ABA temporally regulated the transcript levels of genes encoding ASA-GSH cycle enzymes. Moreover, these genes exhibited differential expression patterns between the root and leaf organs of ABA-treated wheat seedlings during drought stress. These results implied that exogenous ABA increased the levels of GSH and ASA in drought-stressed wheat seedlings in time- and organ-specific manners. Moreover, the transcriptional profiles of ASA-GSH synthesis-related enzyme genes in the leaf tissue were compared between ABA- and salicylic acid (SA-treated wheat seedlings under PEG-stimulated drought stress, suggesting that they increased the contents of ASA and GSH by differentially regulating expression levels of ASA-GSH synthesis enzyme genes. Our results increase our understanding of the molecular mechanism of ABA-induced drought tolerance in higher plants

  19. Expression of Stipa purpurea SpCIPK26 in Arabidopsis thaliana Enhances Salt and Drought Tolerance and Regulates Abscisic Acid Signaling

    Directory of Open Access Journals (Sweden)

    Yanli Zhou

    2016-06-01

    Full Text Available Stipa purpurea (S. purpurea is the dominant plant species in the alpine steppe of the Qinghai-Tibet Plateau, China. It is highly resistant to cold and drought conditions. However, the underlying mechanisms regulating the stress tolerance are unknown. In this study, a CIPK gene from S. purpurea (SpCIPK26 was isolated. The SpCIPK26 coding region consisted of 1392 bp that encoded 464 amino acids. The protein has a highly conserved catalytic structure and regulatory domain. The expression of SpCIPK26 was induced by drought and salt stress. SpCIPK26 overexpression in Arabidopsis thaliana (A. thaliana plants provided increased tolerance to drought and salt stress in an abscisic acid (ABA-dependent manner. Compared with wild-type A. thaliana plants, SpCIPK26-overexpressing plants had higher survival rates, water potentials, and photosynthetic efficiency (Fv/Fm, as well as lower levels of reactive oxygen species (ROS following exposure to drought and salt stress. Gene expression analyses indicated stress-inducible genes (RD29A, RD29B, and ABF2 and a ROS-scavenger gene (CAT1 were upregulated in SpCIPK26-overexpressing plants after stress treatments. All of these marker genes are associated with ABA-responsive cis-acting elements. Additionally, the similarities in the gene expression patterns following ABA, mannitol, and NaCl treatments suggest SpCIPK26 has an important role during plant responses to drought and salt stress and in regulating ABA signaling.

  20. Development of a rapid LC-DAD/FLD method for the simultaneous determination of auxins and abscisic acid in plant extracts.

    Science.gov (United States)

    Bosco, Renato; Caser, Matteo; Vanara, Francesca; Scariot, Valentina

    2013-11-20

    Plant hormones play a crucial role in controlling plant growth and development. These groups of naturally occurring substances trigger physiological processes at very low concentrations, which mandate sensitive techniques for their quantitation. This paper describes a method to quantify endogenous (±)-2-cis-4-trans-abscisic acid, indole-3-acetic acid, indole-3-propionic acid, and indole-3-butyric acid. The method combines high-performance liquid chromatography (HPLC) with diode array and fluorescence detection in a single run. Hybrid tea rose 'Monferrato' matrices (leaves, petals, roots, seeds, androecium, gynoecium, and pollen) were used as references. Rose samples were separated and suspended in extracting methanol, after which (±)-2-cis-4-trans-abscisic acid and auxins were extracted by solvent extraction. Sample solutions were added first to cation solid phase extraction (SPE) cartridges and the eluates to anion SPE cartridges. The acidic hormones were bound to the last column and eluted with 5% phosphoric acid in methanol. Experimental results showed that this approach can be successfully applied to real samples and that sample preparation and total time for routine analysis can be greatly reduced.

  1. Release of GTP Exchange Factor Mediated Down-Regulation of Abscisic Acid Signal Transduction through ABA-Induced Rapid Degradation of RopGEFs

    Science.gov (United States)

    Waadt, Rainer; Schroeder, Julian I.

    2016-01-01

    The phytohormone abscisic acid (ABA) is critical to plant development and stress responses. Abiotic stress triggers an ABA signal transduction cascade, which is comprised of the core components PYL/RCAR ABA receptors, PP2C-type protein phosphatases, and protein kinases. Small GTPases of the ROP/RAC family act as negative regulators of ABA signal transduction. However, the mechanisms by which ABA controls the behavior of ROP/RACs have remained unclear. Here, we show that an Arabidopsis guanine nucleotide exchange factor protein RopGEF1 is rapidly sequestered to intracellular particles in response to ABA. GFP-RopGEF1 is sequestered via the endosome-prevacuolar compartment pathway and is degraded. RopGEF1 directly interacts with several clade A PP2C protein phosphatases, including ABI1. Interestingly, RopGEF1 undergoes constitutive degradation in pp2c quadruple abi1/abi2/hab1/pp2ca mutant plants, revealing that active PP2C protein phosphatases protect and stabilize RopGEF1 from ABA-mediated degradation. Interestingly, ABA-mediated degradation of RopGEF1 also plays an important role in ABA-mediated inhibition of lateral root growth. The presented findings point to a PP2C-RopGEF-ROP/RAC control loop model that is proposed to aid in shutting off ABA signal transduction, to counteract leaky ABA signal transduction caused by “monomeric” PYL/RCAR ABA receptors in the absence of stress, and facilitate signaling in response to ABA. PMID:27192441

  2. Field studies on the regulation of abscisic acid content and germinability during grain development of barley: molecular and chemical analysis of pre-harvest sprouting.

    Science.gov (United States)

    Chono, Makiko; Honda, Ichiro; Shinoda, Shoko; Kushiro, Tetsuo; Kamiya, Yuji; Nambara, Eiji; Kawakami, Naoto; Kaneko, Shigenobu; Watanabe, Yoshiaki

    2006-01-01

    To investigate whether the regulation of abscisic acid (ABA) content was related to germinability during grain development, two cDNAs for 9-cis-epoxycarotenoid dioxygenase (HvNCED1 and HvNCED2) and one cDNA for ABA 8'-hydroxylase (HvCYP707A1), which are enzymes thought to catalyse key regulatory steps in ABA biosynthesis and catabolism, respectively, were cloned from barley (Hordeum vulgare L.). Expression and ABA-quantification analysis in embryo revealed that HvNCED2 is responsible for a significant increase in ABA levels during the early to middle stages of grain development, and HvCYP707A1 is responsible for a rapid decrease in ABA level thereafter. The change in the embryonic ABA content of imbibing grains following dormancy release is likely to reflect changes in the expression patterns of HvNCEDs and HvCYP707A1. A major change between dormant and after-ripened grains occurred in HvCYP707A1; the increased expression of HvCYP707A1 in response to imbibition, followed by a rapid ABA decrease and a high germination percentage, was observed in the after-ripened grains, but not in the dormant grains. Under field conditions, HvNCED2 showed the same expression level and pattern during grain development in 2002, 2003, and 2004, indicating that HvNCED2 expression is regulated in a growth-dependent manner in the grains. By contrast, HvNCED1 and HvCYP707A1 showed a different expression pattern in each year, indicating that the expression of these genes is affected by environmental conditions during grain development. The varied expression levels of these genes during grain development and imbibition, which would have effects on the activity of ABA biosynthesis and catabolism, might be reflected, in part, in the germinability in field-grown barley.

  3. Inhibition of Blue Light-Dependent H+ Pumping by Abscisic Acid in Vicia Guard-Cell Protoplasts.

    Science.gov (United States)

    Goh, C. H.; Kinoshita, T.; Oku, T.; Shimazaki, Ki.

    1996-06-01

    Blue-light (BL)-dependent H+ pumping in guard-cell protoplasts (GCPs) from Vicia faba was inhibited by 65% in the presence of abscisic acid (ABA). The inhibition increased with the time after application of ABA and was concentration dependent with a saturating concentration of 1 [mu]M at pH 6.2. The inhibition was nearly independent of the pH of the medium in the range 5.4 to 7.2 when ABA was applied at 10 [mu]M, whereas it was dependent on pH when the ABA concentration was decreased. The protonated form of ABA was saturating at 40 nM in inhibiting BL-dependent H+ pumping under various experimental conditions, whereas the dissociated form at 500 nM had no inhibitory effect on the pumping, suggesting that the protonated form of ABA is the form active in inhibiting the pumping. Fusicoccin (10 [mu]M), an activator of plasma membrane H+-ATPase, induced H+ pumping from GCPs, and the rate of H+ pumping was decreased to 70% by ABA. In contrast, ABA did not inhibit H+ pumping in isolated microsome vesicles from GCPs. These results suggest that the inhibition of BL-dependent H+ pumping by ABA in GCPs may be due to indirect inactivation of plasma membrane H+-ATPase and/or inhibition of the BL-signaling pathway. The pump inhibition by ABA causes membrane depolarization and can be an initial step to induce stomatal closure and reduces the transpirational water loss under drought stress in the daytime.

  4. The zinc finger transcription factor SlZFP2 negatively regulates abscisic acid biosynthesis and fruit ripening in tomato.

    Science.gov (United States)

    Weng, Lin; Zhao, Fangfang; Li, Rong; Xu, Changjie; Chen, Kunsong; Xiao, Han

    2015-03-01

    Abscisic acid (ABA) regulates plant development and adaptation to environmental conditions. Although the ABA biosynthesis pathway in plants has been thoroughly elucidated, how ABA biosynthetic genes are regulated at the molecular level during plant development is less well understood. Here, we show that the tomato (Solanum lycopersicum) zinc finger transcription factor SlZFP2 is involved in the regulation of ABA biosynthesis during fruit development. Overexpression of SlZFP2 resulted in multiple phenotypic changes, including more branches, early flowering, delayed fruit ripening, lighter seeds, and faster seed germination, whereas down-regulation of its expression caused problematic fruit set, accelerated ripening, and inhibited seed germination. SlZFP2 represses ABA biosynthesis during fruit development through direct suppression of the ABA biosynthetic genes NOTABILIS, SITIENS, and FLACCA and the aldehyde oxidase SlAO1. We also show that SlZFP2 regulates fruit ripening through transcriptional suppression of the ripening regulator COLORLESS NON-RIPENING. Using bacterial one-hybrid screening and a selected amplification and binding assay, we identified the (A/T)(G/C)TT motif as the core binding sequence of SlZFP2. Furthermore, by RNA sequencing profiling, we found that 193 genes containing the SlZFP2-binding motifs in their promoters were differentially expressed in 2 d post anthesis fruits between the SlZFP2 RNA interference line and its nontransgenic sibling. We propose that SlZFP2 functions as a repressor to fine-tune ABA biosynthesis during fruit development and provides a potentially valuable tool for dissecting the role of ABA in fruit ripening.

  5. Dynamic distribution and the role of abscisic acid during seed development of a lady’s slipper orchid, Cypripedium formosanum

    Science.gov (United States)

    Lee, Yung-I; Chung, Mei-Chu; Yeung, Edward C.; Lee, Nean

    2015-01-01

    Background and Aims Although abscisic acid (ABA) is commonly recognized as a primary cause of seed dormancy, there is a lack of information on the role of ABA during orchid seed development. In order to address this issue, the localization and quantification of ABA were determined in developing seeds of Cypripedium formosanum. Methods The endogenous ABA profile of seeds was measured by enzyme-linked immunosorbent assay (ELISA). Temporal and spatial distributions of ABA in developing seeds were visualized by immunohistochemical staining with monoclonal ABA antibodies. Fluoridone was applied to test the causal relationship between ABA content and seed germinability. Key Results ABA content was low at the proembryo stage, then increased rapidly from 120 to 150 days after pollination (DAP), accompanied by a progressive decrease in water content and seed germination. Immunofluorescence signals indicated an increase in fluorescence over time from the proembryo stage to seed maturation. From immunogold labelling, gold particles could be seen within the cytoplasm of embryo-proper cells during the early stages of seed development. As seeds approached maturity, increased localization of gold particles was observed in the periplasmic space, the plasmalemma between embryo-proper cells, the surface wall of the embryo proper, and the inner walls of inner seed-coat cells. At maturity, gold particles were found mainly in the apoplast, such as the surface wall of the embryo proper, and the shrivelled inner and outer seed coats. Injection of fluoridone into capsules resulted in enhanced germination of mature seeds. Conclusions The results indicate that ABA is the key inhibitor of germination in C. formosanum. The distinct accumulation pattern of ABA suggests that it is synthesized in the cytosol of embryo cells during the early stages of seed development, and then exported to the apoplastic region of the cells for subsequent regulatory processes as seeds approach maturity. PMID

  6. Light, genotype, and abscisic acid affect chloroplast positioning in guard cells of Arabidopsis thaliana leaves in distinct ways.

    Science.gov (United States)

    Königer, Martina; Jessen, Brita; Yang, Rui; Sittler, Dorothea; Harris, Gary C

    2010-09-01

    The goal of this study was to investigate the effects of light intensity, genotype, and various chemical treatments on chloroplast movement in guard cells of Arabidopsis thaliana leaves. After treatment at various light intensities (dark, low, and high light), leaf discs were fixed with glutaraldehyde, and imaged using confocal laser microscopy. Each chloroplast was assigned a horizontal (close to pore, center, or epidermal side) and vertical (outer, middle, inner) position. White light had a distinct effect on chloroplast positioning, most notably under high light (HL) when chloroplasts on the upper leaf surface of wild-type (WT) moved from epidermal and center positions toward the pore. This was not the case for phot1-5/phot2-1 or phot2-1 plants, thus phototropins are essential for chloroplast positioning in guard cells. In npq1-2 mutants, fewer chloroplasts moved to the pore position under HL than in WT plants, indicating that white light can affect chloroplast positioning also in a zeaxanthin-dependent way. Cytochalasin B inhibited the movement of chloroplasts to the pore under HL, while oryzalin did not, supporting the idea that actin plays a role in the movement. The movement along actin cables is dependent on CHUP1 since chloroplast positioning in chup1 was significantly altered. Abscisic acid (ABA) caused most chloroplasts in WT and phot1-5/phot2-1 to be localized in the center, middle part of the guard cells irrespective of light treatment. This indicates that not only light but also water stress influences chloroplast positioning.

  7. Cross-talk between calcium-calmodulin and nitric oxide in abscisic acid signaling in leaves of maize plants

    Institute of Scientific and Technical Information of China (English)

    Jianrong Sang; Aying Zhang; Fan Lin; Mingpu Tan; Mingyi Jiang

    2008-01-01

    Using pharmacological and biochemical approaches,the signaling pathways between hydrogen peroxide (H2O2),calcium (Ca2+)-calmodulin (CAM),and nitric oxide (NO) in abscisic acid (ABA)-induced antioxidant defense were investigated in leaves of maize (Zea mays L.) plants.Treatments with ABA,H2O2,and CaCI2 induced increases in the generation of NO in maize mesophyll cells and the activity of nitric oxide synthase (NOS) in the cytosolic and microsomal fractions of maize leaves.However,such increases were blocked by the pretreatments with Ca2+ inhibitors and CaM antagonists.Meanwhile,pretreatments with two NOS inhibitors also suppressed the Ca2+-induced increase in the production of NO.On the other hand,treatments with ABA and the NO donor sodium nitroprusside (SNP) also led to increases in the concentration of cytosolic Ca2+ in protoplasts of mesophyll cells and in the expression of calmodulin 1 (CaMI) gene and the contents of CaM in leaves of maize plants,and the increases induced by ABA were reduced by the pretreatments with a NO scavenger and a NOS inhibitor.Moreover,SNP-induced increases in the expression of the antioxidant genes superoxide dismutase 4 (SOD4),cytosolic ascorbate peroxidase (cAPX),and glutathione reductase 1 (GRI) and the activities of the chloroplastic and cytosolic antioxidant enzymes were arrested by the pretreatments with Ca2+ inhibitors and CaM antagonists.Our results suggest that Ca2+-CaM functions both upstream and downstream of NO production,which is mainly from NOS,in ABA- and H2O2-induced antioxidant defense in leaves of maize plants.

  8. A negative regulator encoded by a rice WRKY gene represses both abscisic acid and gibberellins signaling in aleurone cells.

    Science.gov (United States)

    Zhang, Zhong-Lin; Shin, Margaret; Zou, Xiaolu; Huang, Jianzhi; Ho, Tun-hua David; Shen, Qingxi J

    2009-05-01

    Abscisic acid (ABA) and gibberellins (GAs) control several developmental processes including seed maturation, dormancy, and germination. The antagonism of these two hormones is well-documented. However, recent data from transcription profiling studies indicate that they can function as agonists in regulating the expression of many genes although the underlying mechanism is unclear. Here we report a rice WRKY gene, OsWRKY24, which encodes a protein that functions as a negative regulator of both GA and ABA signaling. Overexpression of OsWRKY24 via particle bombardment-mediated transient expression in aleurone cells represses the expression of two reporter constructs: the beta-glucuronidase gene driven by the GA-inducible Amy32b alpha-amylase promoter (Amy32b-GUS) and the ABA-inducible HVA22 promoter (HVA22-GUS). OsWRKY24 is unlikely a general repressor because it has little effect on the expression of the luciferase reporter gene driven by a constitutive ubiquitin promoter (UBI-Luciferase). As to the GA signaling, OsWRKY24 differs from OsWRKY51 and -71, two negative regulators specifically function in the GA signaling pathway, in several ways. First, OsWRKY24 contains two WRKY domains while OsWRKY51 and -71 have only one; both WRKY domains are essential for the full repressing activity of OsWRKY24. Second, binding of OsWRKY24 to the Amy32b promoter appears to involve sequences in addition to the TGAC cores of the W-boxes. Third, unlike OsWRKY71, OsWRKY24 is stable upon GA treatment. Together, these data demonstrate that OsWRKY24 is a novel type of transcriptional repressor that inhibits both GA and ABA signaling.

  9. Effect of Putrescine, 4-PU-30, and Abscisic Acid on Maize Plants Grown under Normal, Drought, and Rewatering Conditions.

    Science.gov (United States)

    Todorov; Alexieva; Karanov

    1998-12-01

    The experiments were carried out with maize (Zea mays L.) seedlings, hybrid Kneja 530, grown hydroponically in a growth chamber. Twelve-day-old plants were foliar treated with putrescine, N1-(2-chloro-4-pyridyl)-N2-phenylurea (4-PU-30), and abscisic acid (ABA) at concentrations of 10(-5) m. Twenty-four hours later the plants were subjected to a water deficit program, induced by 15% polyethylene glycol (PEG; molecular weight, 6,000). Three days after drought stress half of the plants were transferred to nutrient solution for the next 3 days. The effects of the water shortage, rewatering, and plant growth regulator (PGR) treatment on the fresh and dry weights, leaf pigment content, proline level, relative water content (RWC), transpiration rate, activities of catalase and guaiacol peroxidase, hydrogen peroxide content, and level of the products of lipid peroxidation were studied. It was established that the application of PGRs alleviated to some extent the plant damage provoked by PEG stress. At the end of the water shortage program the plants treated with these PGRs possessed higher fresh weight than drought-subjected control seedlings. It was found also that putrescine increased the dry weight of plants. Under drought, the RWC and transpiration rate of seedlings declined, but PGR treatment reduced these effects. The accumulation of free proline, malondialdehyde, and hydrogen peroxide was prevented in PGR-treated plants compared with the water stress control. The results provided further information about the influence of putrescine, 4-PU-30, and ABA on maize plants grown under normal, drought, and rewatering conditions. Key Words. Maize-Putrescine-4-PU-30-ABA-Drought

  10. Abscisic acid activates a Ca2+-calmodulin-stimulated protein kinase involved in antioxidant defense in maize leaves

    Institute of Scientific and Technical Information of China (English)

    Shucheng Xu

    2010-01-01

     The role of a calcium-dependent and calmodulin(CaM)stimulated protein kinase in abscisic acid(ABA)-induced antioxidant defense was determined in leaves of maize (Zea mays).In-gel kinase assays showed that treatments with ABA or H2O2 induced the activation of a 49-kDa protein kinase and a 52-kDa protein kinase significantly.Furthermore,we showed that the 52-kDa protein kinase has the characteristics of CaM-stimulating activity and is sensitive to calcium-CaM-dependent protein kinase Ⅱ (CaMK Ⅱ)inhibitor KN-93 or CaM antagonist W-7.Treatments with ABA or H2O2 not only induced the acti vation of the 52-kDa protein kinase,but also enhanced the total activities of the antioxidant enzymes,including catalase,ascorbate peroxidase,glutathione reductase,and superoxide dismutase.Such enhancements were blocked by pretreatment with a CaMK inhibitor and a reactive oxygen species(ROS)inhibitor or scavenger.Pretreatment with the CaMK inhibitor also substantially arrested the ABA-induced H2O2 production.Kinase activity enhancements induced by ABA were attenuated by pretreatment with an ROS inhibitor or scavenger.These results suggest that the 52-kDa CaMK is involved in ABA-induced antioxidant defense and that cross-talk between CaMK and H2O2 plays a pivotal role in ABA signaling.We infer that CaMK acts both upstream and downstream of H2O2,but mainly acts between ABA and H2O2 in ABA-induced antioxidant-defensive signaling.

  11. Concurrent profiling of indole-3-acetic acid, abscisic acid, and cytokinins and structurally related purines by high-performance-liquid-chromatography tandem electrospray mass spectrometry

    Directory of Open Access Journals (Sweden)

    Farrow Scott C

    2012-10-01

    Full Text Available Abstract Background Cytokinins (CKs are a group of plant growth regulators that are involved in several plant developmental processes. Despite the breadth of knowledge surrounding CKs and their diverse functions, much remains to be discovered about the full potential of CKs, including their relationship with the purine salvage pathway, and other phytohormones. The most widely used approach to query unknown facets of CK biology utilized functional genomics coupled with CK metabolite assays and screening of CK associated phenotypes. There are numerous different types of assays for determining CK quantity, however, none of these methods screen for the compendium of metabolites that are necessary for elucidating all roles, including purine salvage pathway enzymes in CK metabolism, and CK cross-talk with other phytohormones. Furthermore, all published analytical methods have drawbacks ranging from the required use of radiolabelled compounds, or hazardous derivatization reagents, poor sensitivity, lack of resolution between CK isomers and lengthy run times. Results In this paper, a method is described for the concurrent extraction, purification and analysis of several CKs (freebases, ribosides, glucosides, nucleotides, purines (adenosine monophosphate, inosine, adenosine, and adenine, indole-3-acetic acid, and abscisic acid from hundred-milligram (mg quantities of Arabidopsis thaliana leaf tissue. This method utilizes conventional Bieleski solvents extraction, solid phase purification, and is unique because of its diverse range of detectable analytes, and implementation of a conventional HPLC system with a fused core column that enables good sensitivity without the requirement of a UHPLC system. Using this method we were able to resolve CKs about twice as fast as our previous method. Similarly, analysis of adenosine, indole-3-acetic acid, and abscisic acid, was comparatively rapid. A further enhancement of the method was the utilization of a QTRAP

  12. Apoptosis in barley aleurone during germination and its inhibition by abscisic acid.

    Science.gov (United States)

    Wang, M; Oppedijk, B J; Lu, X; Van Duijn, B; Schilperoort, R A

    1996-12-01

    During germination of barley grains, DNA fragmentation was observed in the aleurone. The appearance of DNA fragmentation in the aleurone layer, observed by TUNEL staining in aleurone sections, started near the embryo and extended to the aleurone cells far from the embryo in a time dependent manner. The same spatial temporal activities of hydrolytic enzymes such as alpha-amylase were observed in aleurone. DNA fragmentation could also be seen in vitro under osmotic stress, in isolated aleurone. During aleurone protoplast isolation, a very enhanced and strong DNA fragmentation occurred which was not seen in protoplast preparations of tobacco leaves. ABA was found to inhibit DNA fragmentation occurring in barley aleurone under osmotic stress condition and during protoplast isolation, while the plant growth regulator gibberellic acid counteracted the effect of ABA. Addition of auxin or cytokinin had no significant effect on DNA fragmentation in these cells. To study the role of phosphorylation in ABA signal transduction leading to control of DNA fragmentation (apoptosis), the effects of the phosphatase inhibitor okadaic acid and of phenylarisine oxide on apoptosis were studied. We hypothesize that the regulation of DNA fragmentation in aleurone plays a very important role in spatial and temporal control of aleurone activities during germination. The possible signal transduction pathway of ABA leading to the regulation of DNA fragmentation is discussed.

  13. Visualisation of abscisic acid and 12-oxo-phytodienoic acid in immature Phaseolus vulgaris L. seeds using desorption electrospray ionisation-imaging mass spectrometry.

    Science.gov (United States)

    Enomoto, Hirofumi; Sensu, Takuya; Sato, Kei; Sato, Futoshi; Paxton, Thanai; Yumoto, Emi; Miyamoto, Koji; Asahina, Masashi; Yokota, Takao; Yamane, Hisakazu

    2017-02-17

    The plant hormone abscisic acid (ABA) and the jasmonic acid related-compound 12-oxo-phytodienoic acid (OPDA) play crucial roles in seed development, dormancy, and germination. However, a lack of suitable techniques for visualising plant hormones has restricted the investigation of their biological mechanisms. In the present study, desorption electrospray ionisation-imaging mass spectrometry (DESI-IMS), a powerful tool for visualising metabolites in biological tissues, was used to visualise ABA and OPDA in immature Phaseolus vulgaris L. seed sections. The mass spectra, peak values and chemical formulae obtained from the analysis of seed sections were consistent with those determined for ABA and OPDA standards, as were the precursor and major fragment ions observed in tandem mass spectrometry (MS/MS) imaging. Furthermore, the precursor and fragment ion images showed similar distribution patterns. In addition, the localisation of ABA and OPDA using DESI-IMS was confirmed using liquid chromatography-MS/MS (LC-MS/MS). The results indicated that ABA was mainly distributed in the radical and cotyledon of the embryo, whereas OPDA was distributed exclusively in external structures, such as the hilum and seed coat. The present study is the first to report the visualisation of plant hormones using IMS, and demonstrates that DESI-IMS is a promising technique for future plant hormone research.

  14. Visualisation of abscisic acid and 12-oxo-phytodienoic acid in immature Phaseolus vulgaris L. seeds using desorption electrospray ionisation-imaging mass spectrometry

    Science.gov (United States)

    Enomoto, Hirofumi; Sensu, Takuya; Sato, Kei; Sato, Futoshi; Paxton, Thanai; Yumoto, Emi; Miyamoto, Koji; Asahina, Masashi; Yokota, Takao; Yamane, Hisakazu

    2017-02-01

    The plant hormone abscisic acid (ABA) and the jasmonic acid related-compound 12-oxo-phytodienoic acid (OPDA) play crucial roles in seed development, dormancy, and germination. However, a lack of suitable techniques for visualising plant hormones has restricted the investigation of their biological mechanisms. In the present study, desorption electrospray ionisation-imaging mass spectrometry (DESI-IMS), a powerful tool for visualising metabolites in biological tissues, was used to visualise ABA and OPDA in immature Phaseolus vulgaris L. seed sections. The mass spectra, peak values and chemical formulae obtained from the analysis of seed sections were consistent with those determined for ABA and OPDA standards, as were the precursor and major fragment ions observed in tandem mass spectrometry (MS/MS) imaging. Furthermore, the precursor and fragment ion images showed similar distribution patterns. In addition, the localisation of ABA and OPDA using DESI-IMS was confirmed using liquid chromatography-MS/MS (LC-MS/MS). The results indicated that ABA was mainly distributed in the radical and cotyledon of the embryo, whereas OPDA was distributed exclusively in external structures, such as the hilum and seed coat. The present study is the first to report the visualisation of plant hormones using IMS, and demonstrates that DESI-IMS is a promising technique for future plant hormone research.

  15. [Influence of abscisic acid and fluridone on the content of phytohormones and polyamines and the level of oxidative stress in plants of Mesembryanthemum crystallinum L. under salinity].

    Science.gov (United States)

    Stetsenko, L A; Vedenicheva, N P; Likhnevsky, R V; Kuznetsov, V V

    2015-01-01

    The effect of abscisic acid (ABA) and fluridone on the content of endogenous phytohormones and free polyamines and the intensity of oxidative stress was studied in plants of Mesembryanthemum crystallinum L. under salinity. It was shown that the pretreatment of plant roots with 1 μM ABA, followed by the action of 300 mM NaCl, caused a protective effect and improved the physiological state of the plants, which was manifested in increased biomass and content of available cytokinins and reduced values of the indicators of oxidative stress. It was noted that the inhibitor fluridone reduced the effect of ABA and acted as a pro-oxidant.

  16. Crucial roles of abscisic acid biogenesis in virulence of rice blast fungus Magnaporthe oryzae

    Directory of Open Access Journals (Sweden)

    Carla eSpence

    2015-12-01

    Full Text Available Rice suffers dramatic yield losses due to blast pathogen Magnaporthe oryzae. Pseudomonas chlororaphis EA105, a bacterium that was isolated from the rice rhizosphere, inhibits M. oryzae. It was shown previously that pre-treatment of rice with EA105 reduced the size of blast lesions through JA- and ETH-mediated ISR. ABA acts antagonistically towards SA, JA, and ETH signaling, to impede plant defense responses. EA105 may be reducing the virulence of M. oryzae by preventing the pathogen from up-regulating the key ABA biosynthetic gene NCED3 in rice roots, as well as a β-glucosidase likely involved in activating conjugated inactive forms of ABA. However, changes in total ABA concentrations were not apparent, provoking the question of whether ABA concentration is an indicator of ABA signaling and response. In the rice-M. oryzae interaction, ABA plays a dual role in disease severity by increasing plant susceptibility and accelerating pathogenesis in the fungus itself. ABA is biosynthesized by M. oryzae. Further, exogenous ABA increased spore germination and appressoria formation, distinct from other plant growth regulators. EA105, which inhibits appressoria formation, counteracted the virulence-promoting effects of ABA on M. oryzae. The role of endogenous fungal ABA in blast disease was confirmed through the inability of a knockout mutant impaired in ABA biosynthesis to form lesions on rice. Therefore, it appears that EA105 is invoking multiple strategies in its protection of rice from blast including direct mechanisms as well as those mediated through plant signaling. ABA is a molecule that is likely implicated in both tactics.

  17. Abscisic acid dynamics in roots detected with genetically encoded FRET sensors.

    Science.gov (United States)

    Jones, Alexander M; Danielson, Jonas Ah; Manojkumar, Shruti N; Lanquar, Viviane; Grossmann, Guido; Frommer, Wolf B

    2014-04-15

    Cytosolic hormone levels must be tightly controlled at the level of influx, efflux, synthesis, degradation and compartmentation. To determine ABA dynamics at the single cell level, FRET sensors (ABACUS) covering a range ∼0.2-800 µM were engineered using structure-guided design and a high-throughput screening platform. When expressed in yeast, ABACUS1 detected concentrative ABA uptake mediated by the AIT1/NRT1.2 transporter. Arabidopsis roots expressing ABACUS1-2µ (Kd∼2 µM) and ABACUS1-80µ (Kd∼80 µM) respond to perfusion with ABA in a concentration-dependent manner. The properties of the observed ABA accumulation in roots appear incompatible with the activity of known ABA transporters (AIT1, ABCG40). ABACUS reveals effects of external ABA on homeostasis, that is, ABA-triggered induction of ABA degradation, modification, or compartmentation. ABACUS can be used to study ABA responses in mutants and quantitatively monitor ABA translocation and regulation, and identify missing components. The sensor screening platform promises to enable rapid fine-tuning of the ABA sensors and engineering of plant and animal hormone sensors to advance our understanding of hormone signaling. DOI: http://dx.doi.org/10.7554/eLife.01741.001.

  18. Transcriptomic analysis reveals the flooding tolerant mechanism in flooding tolerant line and abscisic acid treated soybean.

    Science.gov (United States)

    Yin, Xiaojian; Hiraga, Susumu; Hajika, Makita; Nishimura, Minoru; Komatsu, Setsuko

    2017-03-01

    Soybean is highly sensitive to flooding stress and exhibits markedly reduced plant growth and grain yield under flooding conditions. To explore the mechanisms underlying initial flooding tolerance in soybean, RNA sequencing-based transcriptomic analysis was performed using a flooding-tolerant line and ABA-treated soybean. A total of 31 genes included 12 genes that exhibited similar temporal patterns were commonly changed in these plant groups in response to flooding and they were mainly involved in RNA regulation and protein metabolism. The mRNA expression of matrix metalloproteinase, glucose-6-phosphate isomerase, ATPase family AAA domain-containing protein 1, and cytochrome P450 77A1 was up-regulated in wild-type soybean under flooding conditions; however, no changes were detected in the flooding-tolerant line or ABA-treated soybean. The mRNA expression of cytochrome P450 77A1 was specifically up-regulated in root tips by flooding stress, but returned to the level found in control plants following treatment with the P450 inhibitor uniconazole. The survival ratio and root fresh weight of plants were markedly improved by 3-h uniconazole treatment under flooding stress. Taken together, these results suggest that cytochrome P450 77A1 is suppressed by uniconazole treatment and that this inhibition may enhance soybean tolerance to flooding stress.

  19. The C2H2-type Zinc Finger Protein ZFP182 is Involved in Abscisic Acid-Induced Antioxidant Defense in Rice

    Institute of Scientific and Technical Information of China (English)

    Hong Zhang; Lan Ni; Yanpei Liu; Yunfei Wang; Aying Zhang; Mingpu Tan; Mingyi Jiang

    2012-01-01

    C2H2-type zinc finger proteins (ZFPs) are thought to play important roles in modulating the responses of plants to drought,salinity and oxidative stress.However,direct evidence is lacking for the involvement of these ZFPs in abscisic acid (ABA)-induced antioxidant defense in plants.In this study,the role of the rice (Oryza sativa L.sub.japonica cv.Nipponbare) C2H2-type ZFP ZFP182 in ABA-induced antioxidant defense and the relationship between ZFP182 and two rice MAPKs,OsMPK1 and OsMPK5 in ABA signaling were investigated.ABA treatment induced the increases in the expression of ZFP182,OsMPK1 and OsMPK5,and the activities of superoxide dismutase (SOD) and ascorbate peroxidase (APX) in rice leaves.The transient gene expression analysis and the transient RNA interference (RNAi) analysis in protoplasts showed that ZFP182,OsMPK1 and OsMPK5 are involved in ABA-induced up-regulation in the activities of SOD and APX.Besides,OsMPK1 and OsMPK5 were shown to be required for the up-regulation in the expression of ZFP182 in ABA signaling,but ZFP182 did not mediate the ABA-induced up-regulation in the expression of OsMPK1 and OsMPK5.These results indicate that ZFP182 is required for ABA-induced antioxidant defense and the expression of ZFP182 is regulated by rice MAPKs in ABA signaling.

  20. Drought and salt stress tolerance of an Arabidopsis glutathione S-transferase U17 knockout mutant are attributed to the combined effect of glutathione and abscisic acid.

    Science.gov (United States)

    Chen, Jui-Hung; Jiang, Han-Wei; Hsieh, En-Jung; Chen, Hsing-Yu; Chien, Ching-Te; Hsieh, Hsu-Liang; Lin, Tsan-Piao

    2012-01-01

    Although glutathione S-transferases (GSTs) are thought to play major roles in oxidative stress metabolism, little is known about the regulatory functions of GSTs. We have reported that Arabidopsis (Arabidopsis thaliana) GLUTATHIONE S-TRANSFERASE U17 (AtGSTU17; At1g10370) participates in light signaling and might modulate various aspects of development by affecting glutathione (GSH) pools via a coordinated regulation with phytochrome A. Here, we provide further evidence to support a negative role of AtGSTU17 in drought and salt stress tolerance. When AtGSTU17 was mutated, plants were more tolerant to drought and salt stresses compared with wild-type plants. In addition, atgstu17 accumulated higher levels of GSH and abscisic acid (ABA) and exhibited hyposensitivity to ABA during seed germination, smaller stomatal apertures, a lower transpiration rate, better development of primary and lateral root systems, and longer vegetative growth. To explore how atgstu17 accumulated higher ABA content, we grew wild-type plants in the solution containing GSH and found that they accumulated ABA to a higher extent than plants grown in the absence of GSH, and they also exhibited the atgstu17 phenotypes. Wild-type plants treated with GSH also demonstrated more tolerance to drought and salt stresses. Furthermore, the effect of GSH on root patterning and drought tolerance was confirmed by growing the atgstu17 in solution containing l-buthionine-(S,R)-sulfoximine, a specific inhibitor of GSH biosynthesis. In conclusion, the atgstu17 phenotype can be explained by the combined effect of GSH and ABA. We propose a role of AtGSTU17 in adaptive responses to drought and salt stresses by functioning as a negative component of stress-mediated signal transduction pathways.

  1. Water Deficit and Abscisic Acid Cause Differential Inhibition of Shoot versus Root Growth in Soybean Seedlings : Analysis of Growth, Sugar Accumulation, and Gene Expression.

    Science.gov (United States)

    Creelman, R A; Mason, H S; Bensen, R J; Boyer, J S; Mullet, J E

    1990-01-01

    Roots often continue to elongate while shoot growth is inhibited in plants subjected to low-water potentials. The cause of this differential response to water deficit was investigated. We examined hypocotyl and root growth, polysome status and mRNA populations, and abscisic acid (ABA) content in etiolated soybean (Glycine max [L.] Merr. cv Williams) seedlings whose growth was inhibited by transfer to low-water potential vermiculite or exogenous ABA. Both treatments affected growth and dry weight in a similar fashion. Maximum inhibition of hypocotyl growth occurred when internal ABA levels (modulated by ABA application) reached the endogenous level found in the elongating zone of seedlings grown in water-deficient vermiculite. Conversely, root growth was affected to only a slight extent in low-water potential seedlings and by most ABA treatments (in some, growth was promoted). In every seedling section examined, transfer of seedlings into low-water potential vermiculite caused ABA levels to increase approximately 5- to 10-fold over that found in well-watered seedlings. Changes in soluble sugar content, polysome status, and polysome mRNA translation products seen in low-water potential seedlings did not occur with ABA treatments sufficient to cause significant inhibition of hypocotyl elongation. These data suggest that both variation in endogenous ABA levels, and differing sensitivity to ABA in hypocotyls and roots can modulate root/shoot growth ratios. However, exogenous ABA did not induce changes in sugar accumulation, polysome status, and mRNA populations seen after transfer into low-water potential vermiculite.

  2. An unusual abscisic acid and gibberellic acid synergism increases somatic embryogenesis, facilitates its genetic analysis and improves transformation in Medicago truncatula.

    Directory of Open Access Journals (Sweden)

    Kim E Nolan

    Full Text Available Somatic embryogenesis (SE can be readily induced in leaf explants of the Jemalong 2HA genotype of the model legume Medicago truncatula by auxin and cytokinin, but rarely in wild-type Jemalong. Gibberellic acid (GA, a hormone not included in the medium, appears to act in Arabidopsis as a repressor of the embryonic state such that low ABA (abscisic acid: GA ratios will inhibit SE. It was important to evaluate the GA effect in M. truncatula in order to formulate generic SE mechanisms, given the Arabidopsis information. It was surprising to find that low ABA:GA ratios in M. truncatula acted synergistically to stimulate SE. The unusual synergism between GA and ABA in inducing SE has utility in improving SE for regeneration and transformation in M. truncatula. Expression of genes previously shown to be important in M. truncatula SE was not increased. In investigating genes previously studied in GA investigations of Arabidopsis SE, there was increased expression of GA2ox and decreased expression of PICKLE, a negative regulator of SE in Arabidopsis. We suggest that in M. truncatula there are different ABA:GA ratios required for down-regulating the PICKLE gene, a repressor of the embryonic state. In M. truncatula it is a low ABA:GA ratio while in Arabidopsis it is a high ABA:GA ratio. In different species the expression of key genes is probably related to differences in how the hormone networks optimise their expression.

  3. Regulation of the High-Affinity Nitrate Transport System in Wheat Roots by Exogenous Abscisic Acid and Glutamine

    Institute of Scientific and Technical Information of China (English)

    Chao Cai; Xue-Qiang Zhao; Yong-Guan Zhu; Bin Li; Yi-Ping Tong; Zhen-Sheng Li

    2007-01-01

    Nitrate is a major nitrogen (N) source for most crops.Nitrate uptake by root cells is a key step of nitrogen metabolism and has been widely studied at the physiological and molecular levels.Understanding how nitrate uptake is regulated will help us engineer crops with improved nitrate uptake efficiency.The present study investigated the regulation of the high-affinity nitrate transport system (HATS) by exogenous abscisic acid (ABA) and glutamine (Gin) in wheat (Triticum aestivum L.) roots.Wheat seedlings grown in nutrient solution containing 2 mmollL nitrate as the only nitrogen source for 2 weeks were deprived of N for 4d and were then transferred to nutrient solution containing 50 μmol/L ABA, and 1 mmol/L Gin in the presence or absence of 2 mmol/L nitrate for 0, 0.5, 1, 2, 4, and 8 h.Treated wheat plants were then divided into two groups.One group of plants was used to investigate the mRNA levels of the HATS components NRT2 and NAR2 genes in roots through semi-quantitative RT-PCR approach, and the other set of plants were used to measure high-affinity nitrate influx rates in a nutrient solution containing 0.2 mmol/L 15 N-labeled nitrate.The results showed that exogenous ABA induced the expression of the TaNRT2.1, TaNRT2.2, TaNRT2.3, TaNAR2.1, and TaNAR2.2 genes in roots when nitrate was not present in the nutrient solution, but did not further enhance the induction of these genes by nitrate.Glutamine, which has been shown to inhibit the expression of NRT2 genes when nitrate is present in the growth media, did not inhibit this induction.When Gin was supplied to a nitrate-free nutrient solution, the expression of these five genes in roots was induced.These results imply that the inhibition by Gin of NRT2 expression occurs only when nitrate is present in the growth media.Although exogenous ABA and Gin induced HATS genes in the roots of wheat, they did not induce nitrate influx.

  4. ABI4 regulates primary seed dormancy by regulating the biogenesis of abscisic acid and gibberellins in arabidopsis.

    Science.gov (United States)

    Shu, Kai; Zhang, Huawei; Wang, Shengfu; Chen, Mingluan; Wu, Yaorong; Tang, Sanyuan; Liu, Chunyan; Feng, Yuqi; Cao, Xiaofeng; Xie, Qi

    2013-06-01

    Seed dormancy is an important economic trait for agricultural production. Abscisic acid (ABA) and Gibberellins (GA) are the primary factors that regulate the transition from dormancy to germination, and they regulate this process antagonistically. The detailed regulatory mechanism involving crosstalk between ABA and GA, which underlies seed dormancy, requires further elucidation. Here, we report that ABI4 positively regulates primary seed dormancy, while negatively regulating cotyledon greening, by mediating the biogenesis of ABA and GA. Seeds of the Arabidopsis abi4 mutant that were subjected to short-term storage (one or two weeks) germinated significantly more quickly than Wild-Type (WT), and abi4 cotyledons greened markedly more quickly than WT, while the rates of germination and greening were comparable when the seeds were subjected to longer-term storage (six months). The ABA content of dry abi4 seeds was remarkably lower than that of WT, but the amounts were comparable after stratification. Consistently, the GA level of abi4 seeds was increased compared to WT. Further analysis showed that abi4 was resistant to treatment with paclobutrazol (PAC), a GA biosynthesis inhibitor, during germination, while OE-ABI4 was sensitive to PAC, and exogenous GA rescued the delayed germination phenotype of OE-ABI4. Analysis by qRT-PCR showed that the expression of genes involved in ABA and GA metabolism in dry and germinating seeds corresponded to hormonal measurements. Moreover, chromatin immunoprecipitation qPCR (ChIP-qPCR) and transient expression analysis showed that ABI4 repressed CYP707A1 and CYP707A2 expression by directly binding to those promoters, and the ABI4 binding elements are essential for this repression. Accordingly, further genetic analysis showed that abi4 recovered the delayed germination phenotype of cyp707a1 and cyp707a2 and further, rescued the non-germinating phenotype of ga1-t. Taken together, this study suggests that ABI4 is a key factor that

  5. Regulation of erucic acid accumulation in oilseed rape (Brassica napus L.). Effects of temperature and abscisic acid.

    NARCIS (Netherlands)

    Wilmer, J.A.

    1997-01-01

    Vegetable oils are an important commodity world-wide with an annual production of about 70 million tonnes. Oilseed rape is one of the four major crops, providing about 10% of the total production. Quality of vegetable oils is determined by the fatty acid composition of the triacylglycerols (TAG) tha

  6. Effects of abscisic acid and nitric oxide on trap formation and trapping of nematodes by the fungus Drechslerella stenobrocha AS6.1.

    Science.gov (United States)

    Xu, Ling-Ling; Lai, Yi-Ling; Wang, Lin; Liu, Xing-Zhong

    2011-02-01

    The in vitro effects of abscisic acid (ABA) and nitric oxide (NO) on the nematode-trapping fungus Drechslerella stenobrocha AS6.1 were examined. The average number of traps (constricting rings) per colony and the percentage of nematodes (Caenorhabditis elegans) trapped were greatly increased by addition of ABA but greatly suppressed by addition of sodium nitroprusside (SNP, an NO donor) to corn meal agar. The suppressive effect of SNP was not negated by addition of an NO synthase competitive inhibitor (l-naphthylacetic acid, L-NNA) or an NO-specific scavenger [2-(4-carboxyphenyl)-4,4, 5,5-tetramethylimidazoline-1-oxyl-3-oxide, cPTIO]. When added without SNP, however, L-NNA and cPTIO caused moderate increases in trap number and trapping. The results indicate that the trap formation and nematode-trapping ability of D. stenobrocha were enhanced by ABA but decreased by exogenous NO.

  7. Transcriptional regulation of abscisic acid signal core components during cucumber seed germination and under Cu²⁺, Zn²⁺, NaCl and simulated acid rain stresses.

    Science.gov (United States)

    Wang, Yanping; Wang, Ya; Kai, Wenbin; Zhao, Bo; Chen, Pei; Sun, Liang; Ji, Kai; Li, Qian; Dai, Shengjie; Sun, Yufei; Wang, Yidong; Pei, Yuelin; Leng, Ping

    2014-03-01

    Abscisic acid (ABA) is an important phytohormone that regulates lots of physiological and biochemical processes in plant life cycle, especially in seed germination and stress responses. For exploring the transcriptional regulation of ABA signal transduction during cucumber (Cucumis sativus L.) seed germination and under Cu(2+), Zn(2+), NaCl and simulated acid rain stresses, nine CsPYLs, three group A CsPP2Cs and two subclass III CsSnRK2s were identified from cucumber genome, which respectively showed high sequence similarities and highly conserved domains with homologous genes in Arabidopsis. Based on Real-time PCR analysis, most of the tested genes' expression decreased during cucumber seed germination, which was in accordance with the ABA level variation. In addition, according to the absolute expression, CsPYL1, CsPYL3, CsPP2C5, CsABI1, CsSnRK2.3 and CsSnRK2.4 were highly expressed, indicating that they may play more important roles in ABA signaling during cucumber seed germination. Moreover, most of these highly expressed genes, except CsPYL3, were up-regulated by ABA treatment. Meanwhile, most of the tested genes' expression dramatically changed at the initial water uptake phase, indicating that this period may be critical in the regulation of ABA on seed germination. Under Cu(2+), Zn(2+), NaCl and simulated acid rain stresses, cucumber seed germination percentage decreased and ABA content increased. Meanwhile, the expression of ABA signal transduction core components genes showed specific response to a particular stress and was not always consist with ABA variation. Generally, the expression of CsPYL1, CsPYL3, CsABI1, CsSnRK2.3 and CsSnRK2.4 was sensitive to 120 mM NaCl and 0.5 mM Cu(2+) treatments.

  8. Fruit load induces changes in global gene expression and in abscisic acid (ABA) and indole acetic acid (IAA) homeostasis in citrus buds.

    Science.gov (United States)

    Shalom, Liron; Samuels, Sivan; Zur, Naftali; Shlizerman, Lyudmila; Doron-Faigenboim, Adi; Blumwald, Eduardo; Sadka, Avi

    2014-07-01

    Many fruit trees undergo cycles of heavy fruit load (ON-Crop) in one year, followed by low fruit load (OFF-Crop) the following year, a phenomenon known as alternate bearing (AB). The mechanism by which fruit load affects flowering induction during the following year (return bloom) is still unclear. Although not proven, it is commonly accepted that the fruit or an organ which senses fruit presence generates an inhibitory signal that moves into the bud and inhibits apical meristem transition. Indeed, fruit removal from ON-Crop trees (de-fruiting) induces return bloom. Identification of regulatory or metabolic processes modified in the bud in association with altered fruit load might shed light on the nature of the AB signalling process. The bud transcriptome of de-fruited citrus trees was compared with those of ON- and OFF-Crop trees. Fruit removal resulted in relatively rapid changes in global gene expression, including induction of photosynthetic genes and proteins. Altered regulatory mechanisms included abscisic acid (ABA) metabolism and auxin polar transport. Genes of ABA biosynthesis were induced; however, hormone analyses showed that the ABA level was reduced in OFF-Crop buds and in buds shortly following fruit removal. Additionally, genes associated with Ca(2+)-dependent auxin polar transport were remarkably induced in buds of OFF-Crop and de-fruited trees. Hormone analyses showed that auxin levels were reduced in these buds as compared with ON-Crop buds. In view of the auxin transport autoinhibition theory, the possibility that auxin distribution plays a role in determining bud fate is discussed.

  9. AtPP2CG1, a protein phosphatase 2C, positively regulates salt tolerance of Arabidopsis in abscisic acid-dependent manner

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xin, E-mail: fangfei6073@126.com [Plant Bioengineering Laboratory, Northeast Agricultural University, Harbin 150030 (China); Zhu, Yanming, E-mail: ymzhu2001@neau.edu.cn [Plant Bioengineering Laboratory, Northeast Agricultural University, Harbin 150030 (China); Zhai, Hong, E-mail: Zhai.h@neigaehrb.ac.cn [Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Harbin 150040 (China); Cai, Hua, E-mail: small-big@sohu.com [Plant Bioengineering Laboratory, Northeast Agricultural University, Harbin 150030 (China); Ji, Wei, E-mail: iwei_j@hotmail.com [Plant Bioengineering Laboratory, Northeast Agricultural University, Harbin 150030 (China); Luo, Xiao, E-mail: luoxiao2010@yahoo.cn [Plant Bioengineering Laboratory, Northeast Agricultural University, Harbin 150030 (China); Li, Jing, E-mail: lijing@neau.edu.cn [Plant Secondary Metabolism Laboratory, Northeast Agricultural University, Harbin 150030 (China); Bai, Xi, E-mail: baixi@neau.edu.cn [Plant Bioengineering Laboratory, Northeast Agricultural University, Harbin 150030 (China)

    2012-06-15

    Highlights: Black-Right-Pointing-Pointer AtPP2CG1 positively regulates salt tolerance in ABA-dependent manner. Black-Right-Pointing-Pointer AtPP2CG1 up-regulates the expression of marker genes in different pathways. Black-Right-Pointing-Pointer AtPP2CG1 expresses in the vascular system and trichomes of Arabidopsis. -- Abstract: AtPP2CG1 (Arabidopsis thaliana protein phosphatase 2C G Group 1) was predicted as an abiotic stress candidate gene by bioinformatic analysis in our previous study. The gene encodes a putative protein phosphatase 2C that belongs to Group G of PP2C. There is no report of Group G genes involved in abiotic stress so far. Real-time RT-PCR analysis showed that AtPP2CG1 expression was induced by salt, drought, and abscisic acid (ABA) treatment. The expression levels of AtPP2CG1 in the ABA synthesis-deficient mutant abi2-3 were much lower than that in WT plants under salt stress suggesting that the expression of AtPP2CG1 acts in an ABA-dependent manner. Over-expression of AtPP2CG1 led to enhanced salt tolerance, whereas its loss of function caused decreased salt tolerance. These results indicate that AtPP2CG1 positively regulates salt stress in an ABA-dependent manner. Under salt treatment, AtPP2CG1 up-regulated the expression levels of stress-responsive genes, including RD29A, RD29B, DREB2A and KIN1. GUS activity was detected in roots, leaves, stems, flower, and trichomes of AtPP2CG1 promoter-GUS transgenic plants. AtPP2CG1 protein was localized in nucleus and cytoplasm via AtPP2CG1:eGFP and YFP:AtPP2CG1 fusion approaches.

  10. Glutathione and abscisic acid supplementation influences somatic embryo maturation and hormone endogenous levels during somatic embryogenesis in Podocarpus lambertii Klotzsch ex Endl.

    Science.gov (United States)

    Fraga, Hugo Pacheco de Freitas; Vieira, Leila do Nascimento; Puttkammer, Catarina Corrêa; Dos Santos, Henrique Pessoa; Garighan, Julio de Andrade; Guerra, Miguel Pedro

    2016-12-01

    Here we propose a protocol for embryogenic cultures induction, proliferation and maturation for the Brazilian conifer Podocarpus lambertii, and investigated the effect of abscisic acid (ABA) and glutathione (GSH) supplementation on the maturation phase. ABA, zeatin (Z) and salicylic acid (SA) endogenous levels were quantified. Number of somatic embryos obtained in ABA-supplemented treatment was significant higher than in ABA-free treatment, showing the relevance of ABA supplementation during somatic embryos maturation. Histological analysis showed the stereotyped sequence of developmental stages in conifer somatic embryos, reaching the late torpedo-staged embryo. GSH supplementation in maturation culture medium improved the somatic embryos number and morphological features. GSH 0mM and GSH 0.1mM treatments correlated with a decreased ABA endogenous level during maturation, while GSH 0.5mM treatment showed constant levels. All treatments resulted in decreased Z endogenous levels, supporting the concept that cytokinins are important during the initial cell division but not for the later stages of embryo development. The lowest SA levels found in GSH 0.5mM treatment were coincident with early embryonic development, and this treatment resulted in the highest development of somatic embryos. Thus, a correlation between lower SA levels and improved somatic embryo formation can be hypothesized.

  11. Release of reactive oxygen intermediates (superoxide radicals, hydrogen peroxide, and hydroxyl radicals) and peroxidase in germinating radish seeds controlled by light, gibberellin, and abscisic acid.

    Science.gov (United States)

    Schopfer, P; Plachy, C; Frahry, G

    2001-04-01

    Germination of radish (Raphanus sativus cv Eterna) seeds can be inhibited by far-red light (high-irradiance reaction of phytochrome) or abscisic acid (ABA). Gibberellic acid (GA3) restores full germination under far-red light. This experimental system was used to investigate the release of reactive oxygen intermediates (ROI) by seed coats and embryos during germination, utilizing the apoplastic oxidation of 2',7'-dichlorofluorescin to fluorescent 2',7'-dichlorofluorescein as an in vivo assay. Germination in darkness is accompanied by a steep rise in ROI release originating from the seed coat (living aleurone layer) as well as the embryo. At the same time as the inhibition of germination, far-red light and ABA inhibit ROI release in both seed parts and GA3 reverses this inhibition when initiating germination under far-red light. During the later stage of germination the seed coat also releases peroxidase with a time course affected by far-red light, ABA, and GA3. The participation of superoxide radicals, hydrogen peroxide, and hydroxyl radicals in ROI metabolism was demonstrated with specific in vivo assays. ROI production by germinating seeds represents an active, developmentally controlled physiological function, presumably for protecting the emerging seedling against attack by pathogens.

  12. Quantifying the impact of exogenous abscisic acid and gibberellins on pre-maturity α-amylase formation in developing wheat grains.

    Science.gov (United States)

    Kondhare, Kirtikumar R; Hedden, Peter; Kettlewell, Peter S; Farrell, Aidan D; Monaghan, James M

    2014-06-19

    To study the role of abscisic acid (ABA) and gibberellins (GA) in pre-maturity α-amylase (PMA) formation in developing wheat grain, two glasshouse experiments were conducted under controlled conditions in the highly PMA-susceptible genotype Rialto. The first, determined the relative efficacy of applying hormone solutions by injection into the peduncle compared to direct application to the intact grain. The second, examined the effects of each hormone, applied by either method, at mid-grain development on PMA in mature grains. In the first experiment, tritiated ABA ((3)H-ABA) and gibberellic acid ((3)H-GA3) were diluted with unlabelled ABA (100 µM) and GA3 (50 µM), respectively, and applied at mid-grain development using both methods. Spikes were harvested after 24, 48 and 72 h from application, and hormone taken up by grains was determined. After 72 h, the uptake per grain in terms of hormones applied was approximately 13% for ABA and 8% for GA3 when applied onto the grains, and approximately 17% for ABA and 5% for GA3 when applied by injection. In the second experiment, applied ABA reduced, whereas applied GA3 increased α-amylase activity. This confirmed that exogenously applied ABA and GA were absorbed in sufficient amounts to alter grain metabolism and impact on PMA.

  13. Abscisic acid and hydrogen peroxide induce modification of plasma membrane H(+)-ATPase from Cucumis sativus L. roots under heat shock.

    Science.gov (United States)

    Janicka-Russak, Małgorzata; Kabała, Katarzyna

    2012-11-01

    We examined the effect of heat shock (HS), for 2 h at 48°C, on plasma membrane H(+)-ATPase (PM-H(+)-ATPase) measured as the hydrolytic and H(+)-pumping activity. Some of the plants were transferred after 2 h HS to control temperature for another 24 h, as post-stressed (PS) plants. A significant increase of PM-H(+)-ATPase in plants subjected to HS was observed. The stimulation of PM-H(+)-ATPase was higher in PS plants. Estimation of transcript levels of cucumber PM-H(+)-ATPase in roots indicated that the action of HS affected gene expression levels. Transcript levels of two isoforms, CsHA4 and CsHA8, in PS plants were elevated. The expression of PM-H(+)-ATPase genes was not affected in plants treated for 2 h with HS. HS elevated the endogenous level of abscisic acid (ABA) both in plants treated for 2 h with HS and in PS plants. Moreover, in PS plants, a distinctly higher level of H(2)O(2) was observed. It was also demonstrated that transcript levels of PM-H(+)-ATPase were elevated in cucumber roots after 24-h treatment of plants with ABA or H(2)O(2). Both of these compounds seem to play an important role in increasing ATPase activity during heat stress, because the use of the inhibitors tungstate and DPI restrained stimulation of PM-H(+)-ATPase activity by heat. Moreover, protein blot analysis with an antibody against phosphothreonine and 14-3-3 protein indicated that increased activity of PM-H(+)-ATPase under HS resulted from phosphorylation of the enzyme. Taken together, the data presented here suggest that, under post-heat stress conditions, abscisic acid and hydrogen peroxide are involved in PM-ATPase modification, through stimulation of gene expression of that PM proton pump. Moreover, heat treatment of cucumber plants results in increased phosphorylation of PM-ATPase and thus fast post-translational modification, leading to activation of the enzyme protein.

  14. Progress on Abscisic Acid Biosynthesis and Signal Transduction in Higher Plants%高等植物脱落酸生物合成及其信号转导研究进展

    Institute of Scientific and Technical Information of China (English)

    杨洪强; 接玉玲

    2001-01-01

    绍介了近年来高等植物体脱落酸(ABA)生物合成缺陷型及反应敏感性突变体、逆境胁迫下ABA的合成、ABA生物合成途径以及ABA信号的细胞识别与转导等几方面的研究进展。%Abscisic acid(ABA) plays a major role in plant growth and development, as well as in adaptation to environmental stress. The research of abscisic acid biosynthesis and signal transduction is advancing rapidly in recent years. In this article, it is reviewed that the ABA-biosynthetic mutants and insensitive or ypersensitivive mutants, ABA biosynthesis under stress, the pathway of ABA biosynthesis, ABA signal perception and transduction.

  15. Basic Pentacysteine Proteins Repress Abscisic Acid Insensitive4 Expression via Direct Recruitment of the Polycomb-Repressive Complex 2 in Arabidopsis Root Development.

    Science.gov (United States)

    Mu, Ying; Zou, Meijuan; Sun, Xuwu; He, Baoye; Xu, Xiumei; Liu, Yini; Zhang, Lixin; Chi, Wei

    2017-01-30

    Plant transcription factors generally act in complex regulatory networks that function at multiple levels to govern plant developmental programs. Dissection of the interconnections among different classes of transcription factors can elucidate these regulatory networks and thus improve our understanding of plant development. Here, we investigated the molecular and functional relationships of the transcription factors ABSCISIC ACID INSENSITIVE 4 (ABI4) and members of the BASIC PENTACYSTEINE (BPC) family in lateral root (LR) development of Arabidopsis thaliana Genetic analysis showed that BPCs promote LR development by repressing ABI4 expression. Molecular analysis showed that BPCs bind to the ABI4 promoter and repress ABI4 transcription in roots. BPCs directly recruit the Polycomb Repressive Complex 2 (PRC2) to the ABI4 locus and epigenetically repress ABI4 expression by catalyzing the trimethylation of histone H3 at lysine 27. In addition, BPCs and ABI4 coordinate their activities to fine-tune the levels of PIN-FORMED1, a component of the auxin signaling pathway, and thus modulate LR formation. These results establish a functional relationship between two universal and multiple-role transcription factors and provide insight into the mechanisms of the transcriptional regulatory networks that affect Arabidopsis organogenesis.

  16. Induction of Protection against Paraquat-induced Oxidative Damage by Abscisic Acid in Maize Leaves is Mediated through Mitogen-activated Protein Kinase

    Institute of Scientific and Technical Information of China (English)

    Hai-Dong Ding; Xiao-Hua Zhang; Shu-Cheng Xu; Li-Li Sun; Ming-Yi Jiang; A-Ying Zhang; Yin-Gen Jin

    2009-01-01

    Mitogen-activated protein kinase (MAPK) cascade has been shown to be important components In stress signal trans-duction pathway. In the present study, protection of maize seedlings (Zea mays L.) against paraquat-generated oxidative toxicity by abscisic acid (ABA), its association with MAPK and ZmMPK5, a candidate for MAPK were investigated. Treatment of maize leaves with exogenous ABA led to significant decreases in the content of malondialdehyde, the percentage of ion leakage and the level of protein oxidation (in terms of carbonyl groups) under paraquat (PQ) stress. However, such decreases were blocked by the pretreatment with two MAPK kinase inhibitors PD98059 and U0126. The damage caused by PQ was further aggravated by inhibitors. Two inhibitors also suppressed the total activities of the antioxidant enzymes superoxide dismutase (SOD, EC 1.15.1.1), catalase (CAT, EC 1.11.1.6), ascorbate peroxidase (APX, EC 1.11.1.11), and glutathione reductase (GR, EC 1.6.4.2). Besides, treatment with PQ stimulated the activation of a 46 kDa MAPK, which was identified as ZmMPK5 by in-gel kinase assay with immunoprecipitation. These results reveal that ABA-induced protection against PQ-generated oxidative damage is mediated through MAPK cascade in maize leaves, in which ZmMPK5, a candidate for MAPK, is demonstrated to be involved.

  17. Distinct abscisic acid signaling pathways for modulation of guard cell versus mesophyll cell potassium channels revealed by expression studies in Xenopus laevis oocytes

    Science.gov (United States)

    Sutton, F.; Paul, S. S.; Wang, X. Q.; Assmann, S. M.; Evans, M. L. (Principal Investigator)

    2000-01-01

    Regulation of guard cell ion transport by abscisic acid (ABA) and in particular ABA inhibition of a guard cell inward K(+) current (I(Kin)) is well documented. However, little is known concerning ABA effects on ion transport in other plant cell types. Here we applied patch clamp techniques to mesophyll cell protoplasts of fava bean (Vicia faba cv Long Pod) plants and demonstrated ABA inhibition of an outward K(+) current (I(Kout)). When mesophyll cell protoplast mRNA (mesophyll mRNA) was expressed in Xenopus laevis oocytes, I(Kout) was generated that displayed similar properties to I(Kout) observed from direct analysis of mesophyll cell protoplasts. I(Kout) expressed by mesophyll mRNA-injected oocytes was inhibited by ABA, indicating that the ABA signal transduction pathway observed in mesophyll cells was preserved in the frog oocytes. Co-injection of oocytes with guard cell protoplast mRNA and cRNA for KAT1, an inward K(+) channel expressed in guard cells, resulted in I(Kin) that was similarly inhibited by ABA. However, oocytes co-injected with mesophyll mRNA and KAT1 cRNA produced I(Kin) that was not inhibited by ABA. These results demonstrate that the mesophyll-encoded signaling mechanism could not substitute for the guard cell pathway. These findings indicate that mesophyll cells and guard cells use distinct and different receptor types and/or signal transduction pathways in ABA regulation of K(+) channels.

  18. Chloride-inducible transient apoplastic alkalinizations induce stomata closure by controlling abscisic acid distribution between leaf apoplast and guard cells in salt-stressed Vicia faba.

    Science.gov (United States)

    Geilfus, Christoph-Martin; Mithöfer, Axel; Ludwig-Müller, Jutta; Zörb, Christian; Muehling, Karl H

    2015-11-01

    Chloride stress causes the leaf apoplast transiently to alkalize, an event that is presumed to contribute to the ability of plants to adapt to saline conditions. However, the initiation of coordinated processes downstream of the alkalinization is unknown. We hypothesize that chloride-inducible pH dynamics are a key chemical feature modulating the compartmental distribution of abscisic acid (ABA) and, as a consequence, affecting stomata aperture. Apoplastic pH and stomata aperture dynamics in intact Vicia faba leaves were monitored by microscopy-based ratio imaging and porometric measurements of stomatal conductance. ABA concentrations in leaf apoplast and guard cells were compared with pH dynamics by gas-chromatography-mass-spectrometry (GC-MS) and liquid-chromatography-tandem-mass spectrometry (LC-MS/MS). Results demonstrate that, upon chloride addition to roots, an alkalizing factor that initiates the pH dynamic propagates from root to leaf in a way similar to xylem-distributed water. In leaves, it induces a systemic transient apoplastic alkalinization that causes apoplastic ABA concentration to increase, followed by an elevation of endogenous guard cell ABA. We conclude that the transient alkalinization, which is a remote effect of chloride stress, modulates the compartmental distribution of ABA between the leaf apoplast and the guard cells and, in this way, is instrumental in inducing stomata closure during the beginning of salinity.

  19. In vivo characterization of the effects of abscisic acid and drying protocols associated with the acquisition of desiccation tolerance in alfalfa (Medicago sativa L.) somatic embryos.

    Science.gov (United States)

    Sreedhar, Lekha; Wolkers, Willem F; Hoekstra, Folkert A; Bewley, J Derek

    2002-04-01

    Although somatic embryos of alfalfa (Medicago sativa L.) had acquired some tolerance to desiccation at the cotyledonary stage of development (22 d after plating), additional culturing in 20 microm abscisic acid (ABA) for 8 d induced greater desiccation tolerance, as determined by increased germination. Compared with fast drying, slow drying of the ABA-treated embryos improved desiccation tolerance. However, slow drying of non-ABA-treated embryos led to the complete loss of germination capacity, while some fast-dried embryos survived. An electron paramagnetic resonance spin probe technique and in vivo Fourier transform infrared microspectroscopy revealed that cellular membrane integrity and a-helical protein secondary structure were maintained during drying in embryos cultured in media enriched with 20 microM ABA, but not in embryos cultured in the absence of ABA. Slow-dried, non-ABA-treated embryos had low oligosaccharide to sucrose ratios, an increased proportion of beta-sheet protein secondary structures and broad membrane phase transitions extending over a temperature range of more than 60 degrees C, suggestive of irreversible phase separations. The spin probe study showed evidence of imbibitional damage, which could be alleviated by prehydration in humid air. These observations emphasize the importance of appropriate drying and prehydration protocols for the survival and storage of somatic embryos. It is suggested that ABA also plays a role in suppressing metabolism, thus increasing the level of desiccation tolerance; this is particularly evident under stressful conditions such as slow drying.

  20. Transcriptional coordination and abscisic acid mediated regulation of sucrose transport and sucrose-to-starch metabolism related genes during grain filling in wheat (Triticum aestivum L.).

    Science.gov (United States)

    Mukherjee, Shalini; Liu, Aihua; Deol, Kirandeep K; Kulichikhin, Konstanin; Stasolla, Claudio; Brûlé-Babel, Anita; Ayele, Belay T

    2015-11-01

    Combining physiological, molecular and biochemical approaches, this study investigated the transcriptional coordination and abscisic acid (ABA) mediated regulation of genes involved in sucrose import and its conversion to starch during grain filling in wheat. Sucrose import appears to be mediated by seed localized TaSUT1, mainly TaSUT1D, while sucrose cleavage by TaSuSy2. Temporal overlapping of the transcriptional activation of AGPL1 and AGPS1a that encode AGPase with that of the above genes suggests their significance in the synthesis of ADP-glucose; TaAGPL1A and TaAGPL1D contributing the majority of AGPL1 transcripts. ABA induced repressions of TaSUT1, TaSuSy2, TaAGPL1 and TaAGPS1a imply that ABA negatively regulates sucrose import into the endosperm and its subsequent metabolism to ADP-glucose, the substrate for starch synthesis. The formations of amyloses and amylopectin from ADP-glucose appear to be mediated by specific members of GBSS, and SS, SBE and DBE gene families, and the ABA-induced transcriptional change in most of these genes implies that ABA regulates amylose and amylopectin synthesis. The findings provide insights into the molecular mechanisms underlying the coordination and ABA mediated regulation of sucrose transport into the developing endosperm and its subsequent metabolism to starch during grain filling in wheat.

  1. Arabidopsis WRKY6 Transcription Factor Acts as a Positive Regulator of Abscisic Acid Signaling during Seed Germination and Early Seedling Development.

    Science.gov (United States)

    Huang, Yun; Feng, Cui-Zhu; Ye, Qing; Wu, Wei-Hua; Chen, Yi-Fang

    2016-02-01

    The phytohormone abscisic acid (ABA) plays important roles during seed germination and early seedling development. Here, we characterized the function of the Arabidopsis WRKY6 transcription factor in ABA signaling. The transcript of WRKY6 was repressed during seed germination and early seedling development, and induced by exogenous ABA. The wrky6-1 and wrky6-2 mutants were ABA insensitive, whereas WRKY6-overexpressing lines showed ABA-hypersensitive phenotypes during seed germination and early seedling development. The expression of RAV1 was suppressed in the WRKY6-overexpressing lines and elevated in the wrky6 mutants, and the expression of ABI3, ABI4, and ABI5, which was directly down-regulated by RAV1, was enhanced in the WRKY6-overexpressing lines and repressed in the wrky6 mutants. Electrophoretic mobility shift and chromatin immunoprecipitation assays showed that WRKY6 could bind to the RAV1 promoter in vitro and in vivo. Overexpression of RAV1 in WRKY6-overexpressing lines abolished their ABA-hypersensitive phenotypes, and the rav1 wrky6-2 double mutant showed an ABA-hypersensitive phenotype, similar to rav1 mutant. Together, the results demonstrated that the Arabidopsis WRKY6 transcription factor played important roles in ABA signaling by directly down-regulating RAV1 expression.

  2. Bacteria isolated from roots and rhizosphere of Vitis vinifera retard water losses, induce abscisic acid accumulation and synthesis of defense-related terpenes in in vitro cultured grapevine.

    Science.gov (United States)

    Salomon, María Victoria; Bottini, Rubén; de Souza Filho, Gonçalo Apolinário; Cohen, Ana Carmen; Moreno, Daniela; Gil, Mariana; Piccoli, Patricia

    2014-08-01

    Eleven bacterial strains were isolated at different soil depths from roots and rhizosphere of grapevines from a commercial vineyard. By 16S rRNA gene sequencing 10 different genera and 8 possible at species level were identified. From them, Bacillus licheniformis Rt4M10 and Pseudomonas fluorescens Rt6M10 were selected according to their characteristics as plant growth promoting rhizobacteria (PGPR). Both produced abscisic acid (ABA), indole-3-acetic acid (IAA) and the gibberellins A1 and A3 in chemically-defined medium. They also colonized roots of in vitro grown Vitis vinifera cv. Malbec plants. As result of bacterization ABA levels in 45 days-old in vitro plants were increased 76-fold by B. licheniformis and 40-fold by P. fluorescens as compared to controls. Both bacteria diminished plant water loss rate in correlation with increments of ABA. Twenty and 30 days post bacterization the plants incremented terpenes. The monoterpenes α-pinene, terpinolene, 4-carene, limonene, eucalyptol and lilac aldehyde A, and the sesquiterpenes α-bergamotene, α-farnesene, nerolidol and farnesol were assessed by gas chromatography-electron impact mass spectrometry analysis. α-Pinene and nerolidol were the most abundant (µg per g of tissue in plants bacterized with P. fluorescens). Only α-pinene, eucalyptol and farnesol were identified at low concentration in non-bacterized plants treated with ABA, while no terpenes were detected in controls. The results obtained along with others from literature suggest that B. licheniformis and P. fluorescens act as stress alleviators by inducing ABA synthesis so diminishing water losses. These bacteria also elicit synthesis of compounds of plant defense via an ABA independent mechanism.

  3. Monitoring expression profiles of rice genes under cold, drought, and high-salinity stresses and abscisic acid application using cDNA microarray and RNA gel-blot analyses.

    Science.gov (United States)

    Rabbani, M Ashiq; Maruyama, Kyonoshin; Abe, Hiroshi; Khan, M Ayub; Katsura, Koji; Ito, Yusuke; Yoshiwara, Kyoko; Seki, Motoaki; Shinozaki, Kazuo; Yamaguchi-Shinozaki, Kazuko

    2003-12-01

    To identify cold-, drought-, high-salinity-, and/or abscisic acid (ABA)-inducible genes in rice (Oryza sativa), we prepared a rice cDNA microarray including about 1700 independent cDNAs derived from cDNA libraries prepared from drought-, cold-, and high-salinity-treated rice plants. We confirmed stress-inducible expression of the candidate genes selected by microarray analysis using RNA gel-blot analysis and finally identified a total of 73 genes as stress inducible including 58 novel unreported genes in rice. Among them, 36, 62, 57, and 43 genes were induced by cold, drought, high salinity, and ABA, respectively. We observed a strong association in the expression of stress-responsive genes and found 15 genes that responded to all four treatments. Venn diagram analysis revealed greater cross talk between signaling pathways for drought, ABA, and high-salinity stresses than between signaling pathways for cold and ABA stresses or cold and high-salinity stresses in rice. The rice genome database search enabled us not only to identify possible known cis-acting elements in the promoter regions of several stress-inducible genes but also to expect the existence of novel cis-acting elements involved in stress-responsive gene expression in rice stress-inducible promoters. Comparative analysis of Arabidopsis and rice showed that among the 73 stress-inducible rice genes, 51 already have been reported in Arabidopsis with similar function or gene name. Transcriptome analysis revealed novel stress-inducible genes, suggesting some differences between Arabidopsis and rice in their response to stress.

  4. OsDMI3 Is a Novel Component of Abscisic Acid Signaling in the Induction of Antioxidant Defense in Leaves of Rice

    Institute of Scientific and Technical Information of China (English)

    Ben Shi; Lan Ni; Aying Zhang; Jianmei Cao; Hong Zhang; Tingting Qin; Mingpu Tan; Jianhua Zhang; Mingyi Jiang

    2012-01-01

    Ca2+ and calmodulin (CaM) have been shown to play an important role in abscisic acid (ABA)-induced antioxidant defense.However,it is unknown whether Ca2+/CaM-dependent protein kinase (CCaMK) is involved in the process.In the present study,the role of rice CCaMK,OsDMI3,in ABA-induced antioxidant defense was investigated in leaves of rice (Oryza sativa) plants.Treatments with ABA,H2O2,and polyethylene glycol (PEG) induced the expression of OsDMI3 and the activity of OsDMI3,and H2O2 is required for the ABA-induced increases in the expression and the activity of OsDMI3 under water stress.Subcellular localization analysis showed that OsDMI3 is located in the nucleus,the cytoplasm,and the plasma membrane.The analysis of the transient expression of OsDMI3 in rice protoplasts and the RNA interference (RNAi) silencing of OsDMI3 in rice protoplasts showed that OsDMI3 is required for ABA-induced increases in the expression and the activities of superoxide dismutase (SOD) and catalase (CAT).Further,the oxidative damage induced by higher concentrations of PEG and H2O2 was aggravated in the mutant of OsDMI3.Moreover,the analysis of the RNAi silencing of OsDMI3 in protoplasts and the mutant of OsDMI3 showed that higher levels of H2O2 accumulation require OsDMI3 activation in ABA signaling,but the initial H2O2 production induced by ABA is not dependent on the activation of OsDMI3 in leaves of rice plants.Our data reveal that OsDMI3 is an important component in ABA-induced antioxidant defense in rice.

  5. Effects of exogenous plant growth regulator abscisic acid-induced resistance in rice on the expression of vitellogenin mRNA in Nilaparvata lugens (Hemiptera: Delphacidae) adult females.

    Science.gov (United States)

    Liu, Jing-Lan; Chen, Xiao; Zhang, Hong-Mei; Yang, Xia; Wong, Andrew

    2014-01-01

    Recent study showed that exogenous abscisic acid (ABA) acts as a regulator of plant resistance. This study investigated average injury scale and callose contents of rice, and vitellogenin (Nlvg) mRNA expression in Nilaparvata lugens (Stål) (Hemiptera: Delphacidae) adult females after third instar nymphs fed on exogenous ABA-treated susceptible [Taichung Native one (TN1)] and moderately resistant (IR42) rice cultivars. The results showed that exogenous ABA significantly decreased average injury scale of rice and Nlvg mRNA expression in N. lugens adults compared with the control (without ABA spraying). Nlvg mRNA expression in N. lugens adults decreased significantly after third instar nymphs fed on ABA-treated (5, 20, and 40 mg/liter) TN1 for 1 and 2 d, and for IR42, after fed on ABA-treated (20 and 40 mg/liter) rice plants for 1 d and after fed on ABA-treated (5, 20, and 40 mg/liter) rice for 2 d decreased significantly. The callose contents showed no significant change for TN1, while for IR42, significantly increased in roots and sheathes after N. lugens infestation under ABA treatments (20 and 40 mg/liter) compared with the control. The decrease of Nlvg mRNA expression may be partially attributed to the increase of callose content of plants. The results provide a profile for concerning the effects of ABA-induced rice plants' defenses on phloem-feeding insects.

  6. The Maize Viviparous8 locus, encoding a putative ALTERED MERISTEM PROGRAM1-like peptidase, regulates abscisic acid accumulation and coordinates embryo and endosperm development.

    Science.gov (United States)

    Suzuki, Masaharu; Latshaw, Susan; Sato, Yutaka; Settles, A Mark; Koch, Karen E; Hannah, L Curtis; Kojima, Mikiko; Sakakibara, Hitoshi; McCarty, Donald R

    2008-03-01

    We describe a mutant of Zea mays isolated from a W22 inbred transposon population, widow's peak mutant1 (wpk1), with an altered pattern of anthocyanin synthesis and aleurone cell differentiation in endosperm. In addition, a failure of the developing mutant embryo to form leaf initials is associated with decreased expression of a subset of meristem regulatory genes that includes Abphyl1 and Td1. We show that the viviparous8 (vp8) mutant has a similar pleiotropic phenotype in the W22 inbred background in contrast to the viviparous embryo phenotype exhibited in the standard genetic background, and we confirmed that wpk1 is allelic to vp8. Further genetic analysis revealed that the standard vp8 stock contains an unlinked, partially dominant suppressor of the vp8 mutation that is not present in W22. Consistent with the early-onset viviparous phenotype of vp8, expression of several embryonic regulators, including LEC1/B3 domain transcription factors, was reduced in the mutant embryo. Moreover, reduced abscisic acid (ABA) content of vp8/wpk1 embryos was correlated with altered regulation of ABA biosynthesis, as well as ABA catabolic pathways. The ABA biosynthetic gene Vp14 was down-regulated in the nonsuppressed background, whereas the ZmABA8'oxA1a ABA 8'-hydroxylase gene was strongly up-regulated in both genetic backgrounds. Molecular analysis revealed that Vp8 encodes a putative peptidase closely related to Arabidopsis thaliana ALTERED MERISTEM PROGRAM1. Because the Vp8 regulates meristem development as well as seed maturation processes, including ABA accumulation, we propose that VP8 is required for synthesis of an unidentified signal that integrates meristem and embryo formation in seeds.

  7. The Maize Viviparous8 Locus, Encoding a Putative ALTERED MERISTEM PROGRAM1-Like Peptidase, Regulates Abscisic Acid Accumulation and Coordinates Embryo and Endosperm Development1[W

    Science.gov (United States)

    Suzuki, Masaharu; Latshaw, Susan; Sato, Yutaka; Settles, A. Mark; Koch, Karen E.; Hannah, L. Curtis; Kojima, Mikiko; Sakakibara, Hitoshi; McCarty, Donald R.

    2008-01-01

    We describe a mutant of Zea mays isolated from a W22 inbred transposon population, widow's peak mutant1 (wpk1), with an altered pattern of anthocyanin synthesis and aleurone cell differentiation in endosperm. In addition, a failure of the developing mutant embryo to form leaf initials is associated with decreased expression of a subset of meristem regulatory genes that includes Abphyl1 and Td1. We show that the viviparous8 (vp8) mutant has a similar pleiotropic phenotype in the W22 inbred background in contrast to the viviparous embryo phenotype exhibited in the standard genetic background, and we confirmed that wpk1 is allelic to vp8. Further genetic analysis revealed that the standard vp8 stock contains an unlinked, partially dominant suppressor of the vp8 mutation that is not present in W22. Consistent with the early-onset viviparous phenotype of vp8, expression of several embryonic regulators, including LEC1/B3 domain transcription factors, was reduced in the mutant embryo. Moreover, reduced abscisic acid (ABA) content of vp8/wpk1 embryos was correlated with altered regulation of ABA biosynthesis, as well as ABA catabolic pathways. The ABA biosynthetic gene Vp14 was down-regulated in the nonsuppressed background, whereas the ZmABA8′oxA1a ABA 8′-hydroxylase gene was strongly up-regulated in both genetic backgrounds. Molecular analysis revealed that Vp8 encodes a putative peptidase closely related to Arabidopsis thaliana ALTERED MERISTEM PROGRAM1. Because the Vp8 regulates meristem development as well as seed maturation processes, including ABA accumulation, we propose that VP8 is required for synthesis of an unidentified signal that integrates meristem and embryo formation in seeds. PMID:18203869

  8. Abscisic Acid Induced Changes in Production of Primary and Secondary Metabolites, Photosynthetic Capacity, Antioxidant Capability, Antioxidant Enzymes and Lipoxygenase Inhibitory Activity of Orthosiphon stamineus Benth.

    Directory of Open Access Journals (Sweden)

    Mohd Hafiz Ibrahim

    2013-07-01

    Full Text Available An experiment was conducted to investigate and distinguish the relationships in the production of total phenolics, total flavonoids, soluble sugars, H2O2, O2−, phenylalanine ammonia lyase (PAL activity, leaf gas exchange, antioxidant activity, antioxidant enzyme activity [ascorbate peroxidase (APX, catalase (CAT, superoxide dismutase (SOD and Lipoxygenase inhibitory activity (LOX] under four levels of foliar abscisic acid (ABA application (0, 2, 4, 6 µM for 15 weeks in Orthosiphon stamineus Benth. It was found that the production of plant secondary metabolites, soluble sugars, antioxidant activity, PAL activity and LOX inhibitory activity was influenced by foliar application of ABA. As the concentration of ABA was increased from 0 to 6 µM the production of total phenolics, flavonoids, sucrose, H2O2, O2−, PAL activity and LOX inhibitory activity was enhanced. It was also observed that the antioxidant capabilities (DPPH and ORAC were increased. This was followed by increases in production of antioxidant enzymes APX, CAT and SOD. Under high application rates of ABA the net photosynthesis and stomatal conductance was found to be reduced. The production of primary and secondary metabolites displayed a significant positive relationship with H2O2 (total phenolics, r2 = 0.877; total flavonoids, r2 = 0.812; p ≤ 0.05 and O2− (total phenolics, r2 = 0.778; total flavonoids, r2 = 0.912; p ≤ 0.05. This indicated that increased oxidative stress at high application rates of ABA, improved the production of phytochemicals.

  9. Suppression Subtractive Hybridization Analysis of Genes Regulated by Application of Exogenous Abscisic Acid in Pepper Plant (Capsicum annuum L.) Leaves under Chilling Stress.

    Science.gov (United States)

    Guo, Wei-Li; Chen, Ru-Gang; Gong, Zhen-Hui; Yin, Yan-Xu; Li, Da-Wei

    2013-01-01

    Low temperature is one of the major factors limiting pepper (Capsicum annuum L.) production during winter and early spring in non-tropical regions. Application of exogenous abscisic acid (ABA) effectively alleviates the symptoms of chilling injury, such as wilting and formation of necrotic lesions on pepper leaves; however, the underlying molecular mechanism is not understood. The aim of this study was to identify genes that are differentially up- or downregulated in ABA-pretreated hot pepper seedlings incubated at 6°C for 48 h, using a suppression subtractive hybridization (SSH) method. A total of 235 high-quality ESTs were isolated, clustered and assembled into a collection of 73 unigenes including 18 contigs and 55 singletons. A total of 37 unigenes (50.68%) showed similarities to genes with known functions in the non-redundant database; the other 36 unigenes (49.32%) showed low similarities or unknown functions. Gene ontology analysis revealed that the 37 unigenes could be classified into nine functional categories. The expression profiles of 18 selected genes were analyzed using quantitative RT-PCR; the expression levels of 10 of these genes were at least two-fold higher in the ABA-pretreated seedlings under chilling stress than water-pretreated (control) plants under chilling stress. In contrast, the other eight genes were downregulated in ABA-pretreated seedlings under chilling stress, with expression levels that were one-third or less of the levels observed in control seedlings under chilling stress. These results suggest that ABA can positively and negatively regulate genes in pepper plants under chilling stress.

  10. Suppression Subtractive Hybridization Analysis of Genes Regulated by Application of Exogenous Abscisic Acid in Pepper Plant (Capsicum annuum L. Leaves under Chilling Stress.

    Directory of Open Access Journals (Sweden)

    Wei-Li Guo

    Full Text Available Low temperature is one of the major factors limiting pepper (Capsicum annuum L. production during winter and early spring in non-tropical regions. Application of exogenous abscisic acid (ABA effectively alleviates the symptoms of chilling injury, such as wilting and formation of necrotic lesions on pepper leaves; however, the underlying molecular mechanism is not understood. The aim of this study was to identify genes that are differentially up- or downregulated in ABA-pretreated hot pepper seedlings incubated at 6°C for 48 h, using a suppression subtractive hybridization (SSH method. A total of 235 high-quality ESTs were isolated, clustered and assembled into a collection of 73 unigenes including 18 contigs and 55 singletons. A total of 37 unigenes (50.68% showed similarities to genes with known functions in the non-redundant database; the other 36 unigenes (49.32% showed low similarities or unknown functions. Gene ontology analysis revealed that the 37 unigenes could be classified into nine functional categories. The expression profiles of 18 selected genes were analyzed using quantitative RT-PCR; the expression levels of 10 of these genes were at least two-fold higher in the ABA-pretreated seedlings under chilling stress than water-pretreated (control plants under chilling stress. In contrast, the other eight genes were downregulated in ABA-pretreated seedlings under chilling stress, with expression levels that were one-third or less of the levels observed in control seedlings under chilling stress. These results suggest that ABA can positively and negatively regulate genes in pepper plants under chilling stress.

  11. Gene expression and metabolite profiling of developing highbush blueberry fruit indicates transcriptional regulation of flavonoid metabolism and activation of abscisic acid metabolism.

    Science.gov (United States)

    Zifkin, Michael; Jin, Alena; Ozga, Jocelyn A; Zaharia, L Irina; Schernthaner, Johann P; Gesell, Andreas; Abrams, Suzanne R; Kennedy, James A; Constabel, C Peter

    2012-01-01

    Highbush blueberry (Vaccinium corymbosum) fruits contain substantial quantities of flavonoids, which are implicated in a wide range of health benefits. Although the flavonoid constituents of ripe blueberries are known, the molecular genetics underlying their biosynthesis, localization, and changes that occur during development have not been investigated. Two expressed sequence tag libraries from ripening blueberry fruit were constructed as a resource for gene identification and quantitative real-time reverse transcription-polymerase chain reaction primer design. Gene expression profiling by quantitative real-time reverse transcription-polymerase chain reaction showed that flavonoid biosynthetic transcript abundance followed a tightly regulated biphasic pattern, and transcript profiles were consistent with the abundance of the three major classes of flavonoids. Proanthocyanidins (PAs) and corresponding biosynthetic transcripts encoding anthocyanidin reductase and leucoanthocyanidin reductase were most concentrated in young fruit and localized predominantly to the inner fruit tissue containing the seeds and placentae. Mean PA polymer length was seven to 8.5 subunits, linked predominantly via B-type linkages, and was relatively constant throughout development. Flavonol accumulation and localization patterns were similar to those of the PAs, and the B-ring hydroxylation pattern of both was correlated with flavonoid-3'-hydroxylase transcript abundance. By contrast, anthocyanins accumulated late in maturation, which coincided with a peak in flavonoid-3-O-glycosyltransferase and flavonoid-3'5'-hydroxylase transcripts. Transcripts of VcMYBPA1, which likely encodes an R2R3-MYB transcriptional regulator of PA synthesis, were prominent in both phases of development. Furthermore, the initiation of ripening was accompanied by a substantial rise in abscisic acid, a growth regulator that may be an important component of the ripening process and contribute to the regulation of

  12. Effects of abscisic acid, ethylene and sugars on the mobilization of storage proteins and carbohydrates in seeds of the tropical tree Sesbania virgata (Leguminosae)

    Science.gov (United States)

    Tonini, Patricia Pinho; Purgatto, Eduardo; Buckeridge, Marcos Silveira

    2010-01-01

    Background and Aims Endospermic legumes are abundant in tropical forests and their establishment is closely related to the mobilization of cell-wall storage polysaccharides. Endosperm cells also store large numbers of protein bodies that play an important role as a nitrogen reserve in this seed. In this work, a systems approach was adopted to evaluate some of the changes in carbohydrates and hormones during the development of seedlings of the rain forest tree Sesbania virgata during the period of establishment. Methods Seeds imbibed abscisic acid (ABA), glucose and sucrose in an atmosphere of ethylene, and the effects of these compounds on the protein contents, α-galactosidase activity and endogenous production of ABA and ethylene by the seeds were observed. Key Results The presence of exogenous ABA retarded the degradation of storage protein in the endosperm and decreased α-galactosidase activity in the same tissue during galactomannan degradation, suggesting that ABA represses enzyme action. On the other hand, exogenous ethylene increased α-galactosidase activity in both the endosperm and testa during galactomannan degradation, suggesting an inducing effect of this hormone on the hydrolytic enzymes. Furthermore, the detection of endogenous ABA and ethylene production during the period of storage mobilization and the changes observed in the production of these endogenous hormones in the presence of glucose and sucrose, suggested a correlation between the signalling pathway of these hormones and the sugars. Conclusions These findings suggest that ABA, ethylene and sugars play a role in the control of the hydrolytic enzyme activities in seeds of S. virgata, controlling the process of storage degradation. This is thought to ensure a balanced flow of the carbon and nitrogen for seedling development. PMID:20705626

  13. The APETALA-2-like transcription factor OsAP2-39 controls key interactions between abscisic acid and gibberellin in rice.

    Directory of Open Access Journals (Sweden)

    Mahmoud W Yaish

    2010-09-01

    Full Text Available The interaction between phytohormones is an important mechanism which controls growth and developmental processes in plants. Deciphering these interactions is a crucial step in helping to develop crops with enhanced yield and resistance to environmental stresses. Controlling the expression level of OsAP2-39 which includes an APETALA 2 (AP2 domain leads to phenotypic changes in rice. Overexpression of OsAP2-39 leads to a reduction in yield by decreasing the biomass and the number of seeds in the transgenic rice lines. Global transcriptome analysis of the OsAP2-39 overexpression transgenic rice revealed the upregulation of a key abscisic acid (ABA biosynthetic gene OsNCED-I which codes for 9-cis-epoxycarotenoid dioxygenase and leads to an increase in the endogenous ABA level. In addition to OsNCED-1, the gene expression analysis revealed the upregulation of a gene that codes for the Elongation of Upper most Internode (EUI protein, an enzyme that catalyzes 16α, 17-epoxidation of non-13-hydroxylated GAs, which has been shown to deactivate gibberellins (GAs in rice. The exogenous application of GA restores the wild-type phenotype in the transgenic line and ABA application induces the expression of EUI and suppresses the expression of OsAP2-39 in the wild-type line. These observations clarify the antagonistic relationship between ABA and GA and illustrate a mechanism that leads to homeostasis of these hormones. In vivo and in vitro analysis showed that the expression of both OsNCED-1 and EUI are directly controlled by OsAP2-39. Together, these results reveal a novel mechanism for the control of the ABA/GA balance in rice which is regulated by OsAP2-39 that in turn regulates plant growth and seed production.

  14. Storage behavior and changes in concentrations of abscisic acid and gibberellins during dormancy break and germination in seeds of Phellodendron amurense var. wilsonii (Rutaceae).

    Science.gov (United States)

    Chen, Shun-Ying; Chien, Ching-Te; Baskin, Jerry M; Baskin, Carol C

    2010-02-01

    The medicinal Asian plant genus Phellodendron is known to contain several very important compounds that have biological action. The main purpose of this study was to determine whether seeds of Phellodendron amurense var. wilsonii can be stored and to characterize their dormancy. Seeds of this taxon stored at -20 and -80 degrees C and in liquid nitrogen retained their high germinability, indicating that they have orthodox storage behavior. Intact seeds from freshly collected fruits were dormant and required 12 weeks of cold stratification at 4 degrees C for complete germination. Scarifying the seed coat was partially effective in breaking seed dormancy. Exogenous gibberellins (GA(3), GA(4) and GA(4+7)) promoted germination of scarified seeds, GA(4) and GA(4+7) being more effective than GA(3). Fluridone, an abscisic acid (ABA) biosynthesis inhibitor, was efficient in breaking dormancy, but it was less effective than GA(4) or GA(4+7) alone. Paclobutrazol, a GA biosynthesis inhibitor, inhibited seed germination, and the inhibitory effect was reversed completely by GA(4) and by GA(4+7). ABA content of seeds subjected to cold stratification or to incubation at 35/10 degrees C, which enhanced seed germination, was reduced about four- to sixfold compared to that of fresh seeds. Higher concentrations of GA(3), GA(4) and GA(7) were detected in nondormant seeds and in seeds with an emerged radicle than in fresh seeds. Present results seem to indicate that dormancy in P. amurense var. wilsonii seeds is imposed partially by the seed coat and partially by high ABA content. ABA content decreased and GA(3), GA(4) and GA(7) content increased during germination.

  15. Powdery Mildew Resistance Conferred by Loss of the ENHANCED DISEASE RESISTANCE1 Protein Kinase Is Suppressed by a Missense Mutation in KEEP ON GOING, a Regulator of Abscisic Acid Signaling1[W][OA

    Science.gov (United States)

    Wawrzynska, Anna; Christiansen, Katy M.; Lan, Yinan; Rodibaugh, Natalie L.; Innes, Roger W.

    2008-01-01

    Loss-of-function mutations in the Arabidopsis (Arabidopsis thaliana) ENHANCED DISEASE RESISTANCE1 (EDR1) gene confer enhanced resistance to infection by powdery mildew (Golovinomyces cichoracearum). EDR1 encodes a protein kinase, but its substrates and the pathways regulated by EDR1 are unknown. To identify components of the EDR1 signal transduction pathway(s), we conducted a forward genetic screen for mutations that suppressed edr1-mediated disease resistance. Genetic mapping and cloning of one of these suppressor mutations revealed a recessive missense mutation in the KEEP ON GOING gene (KEG; At5g13530), which we designated keg-4. KEG encodes a multidomain protein that includes a RING E3 ligase domain, a kinase domain, ankyrin repeats, and HERC2-like repeats. The KEG protein has previously been shown to have ubiquitin ligase activity and to negatively regulate protein levels of the transcription factor ABCISIC ACID INSENSITIVE5. KEG mRNA levels were found to be 3-fold higher in edr1 mutant plants compared to wild type. Loss-of-function mutations in KEG are seedling lethal and are hypersensitive to glucose and abscisic acid (ABA). The keg-4 mutation, in contrast, conferred resistance to 6% glucose and suppressed edr1-mediated hypersensitivity to ABA, suggesting that the keg-4 mutation suppresses ABA signaling by altering KEG function. Several ABA-responsive genes were found to be further up-regulated in the edr1 mutant following ABA treatment, and this up-regulation was suppressed by the keg-4 mutation. We conclude that edr1-mediated resistance to powdery mildew is mediated, in part, by enhanced ABA signaling. PMID:18815384

  16. Powdery mildew resistance conferred by loss of the ENHANCED DISEASE RESISTANCE1 protein kinase is suppressed by a missense mutation in KEEP ON GOING, a regulator of abscisic acid signaling.

    Science.gov (United States)

    Wawrzynska, Anna; Christiansen, Katy M; Lan, Yinan; Rodibaugh, Natalie L; Innes, Roger W

    2008-11-01

    Loss-of-function mutations in the Arabidopsis (Arabidopsis thaliana) ENHANCED DISEASE RESISTANCE1 (EDR1) gene confer enhanced resistance to infection by powdery mildew (Golovinomyces cichoracearum). EDR1 encodes a protein kinase, but its substrates and the pathways regulated by EDR1 are unknown. To identify components of the EDR1 signal transduction pathway(s), we conducted a forward genetic screen for mutations that suppressed edr1-mediated disease resistance. Genetic mapping and cloning of one of these suppressor mutations revealed a recessive missense mutation in the KEEP ON GOING gene (KEG; At5g13530), which we designated keg-4. KEG encodes a multidomain protein that includes a RING E3 ligase domain, a kinase domain, ankyrin repeats, and HERC2-like repeats. The KEG protein has previously been shown to have ubiquitin ligase activity and to negatively regulate protein levels of the transcription factor ABCISIC ACID INSENSITIVE5. KEG mRNA levels were found to be 3-fold higher in edr1 mutant plants compared to wild type. Loss-of-function mutations in KEG are seedling lethal and are hypersensitive to glucose and abscisic acid (ABA). The keg-4 mutation, in contrast, conferred resistance to 6% glucose and suppressed edr1-mediated hypersensitivity to ABA, suggesting that the keg-4 mutation suppresses ABA signaling by altering KEG function. Several ABA-responsive genes were found to be further up-regulated in the edr1 mutant following ABA treatment, and this up-regulation was suppressed by the keg-4 mutation. We conclude that edr1-mediated resistance to powdery mildew is mediated, in part, by enhanced ABA signaling.

  17. Dormancy termination of western white pine (Pinus monticola Dougl. Ex D. Don) seeds is associated with changes in abscisic acid metabolism.

    Science.gov (United States)

    Feurtado, J Allan; Ambrose, Stephen J; Cutler, Adrian J; Ross, Andrew R S; Abrams, Suzanne R; Kermode, Allison R

    2004-02-01

    Western white pine (Pinus monticola) seeds exhibit deep dormancy at maturity and seed populations require several months of moist chilling to reach their uppermost germination capacities. Abscisic acid (ABA) and its metabolites, phaseic acid (PA), dihydrophaseic acid (DPA), 7'-hydroxy ABA (7'OH ABA) and ABA-glucose ester (ABA-GE), were quantified in western white pine seeds during dormancy breakage (moist chilling) and germination using an HPLC-tandem mass spectrometry method with multiple reaction monitoring and internal standards incorporating deuterium-labeled analogs. In the seed coat, ABA and metabolite levels were high in dry seeds, but declined precipitously during the pre-moist-chilling water soak to relatively low levels thereafter. In the embryo and megagametophyte, ABA levels decreased significantly during moist chilling, coincident with an increase in the germination capacity of seeds. ABA catabolism occurred via several routes, depending on the stage and the seed tissue. Moist chilling of seeds led to increases in PA and DPA levels in both the embryo and megagametophyte. Within the embryo, 7'OH ABA and ABA-GE also accumulated during moist chilling; however, 7'OH ABA peaked early in germination. Changes in ABA flux, i.e. shifts in the ratio between biosynthesis and catabolism, occurred at three distinct stages during the transition from dormant seed to seedling. During moist chilling, the relative rate of ABA catabolism exceeded ABA biosynthesis. This trend became even more pronounced during germination, and germination was also accompanied by a decrease in the ABA catabolites DPA and PA, presumably as a result of their further metabolism and/or leaching/transport. The transition from germination to post-germinative growth was accompanied by a shift toward ABA biosynthesis. Dormant imbibed seeds, kept in warm moist conditions for 30 days (after an initial 13 days of soaking), maintained high ABA levels, while the amounts of PA, 7'OH ABA, and DPA

  18. Functional annotation of the transcriptome of Sorghum bicolor in response to osmotic stress and abscisic acid

    Science.gov (United States)

    Higher plants exhibit remarkable phenotypic plasticity allowing them to adapt to an extensive range of environmental conditions, and the range of adaptation exhibited by a plant species determines its utility in agriculture. Sorghum is a cereal crop that exhibits unusual tolerance to adverse condit...

  19. Abscisic acid, H2O2 and nitric oxide interactions mediated cold-induced S-adenosylmethionine synthetase in Medicago sativa subsp. falcata that confers cold tolerance through up-regulating polyamine oxidation.

    Science.gov (United States)

    Guo, Zhenfei; Tan, Jiali; Zhuo, Chunliu; Wang, Congying; Xiang, Bin; Wang, Zengyu

    2014-06-01

    S-adenosylmethionine synthetase (SAMS) is the key enzyme catalysing the formation of S-adenosylmethionine (SAM), a precursor of polyamines and ethylene. To investigate the potential role of SAMS in cold tolerance, we isolated MfSAMS1 from the cold-tolerant germplasm Medicago sativa subsp. falcata and analysed the association of SAM-derived polyamines with cold tolerance. The expression of MfSAMS1 in leaves was greatly induced by cold, abscisic acid (ABA), H2O2 and nitric oxide (NO). Our data revealed that ABA, H2O2 and NO interactions mediated the cold-induced MfSAMS1 expression and cold acclimation in falcata. SAM, putrescine, spermidine and spermine levels, ethylene production and polyamine oxidation were sequentially altered in response to cold, indicating that SAMS-derived SAM is preferentially used in polyamine synthesis and homeostasis during cold acclimation. Antioxidant enzyme activities were also induced in response to cold and showed correlation with polyamine oxidation. Overexpression of MfSAMS1 in tobacco resulted in elevated SAM levels, but polyamine levels and ethylene production in the transgenic plants were not significantly changed. Compared to the wild type, transgenic plants had increased levels of apoplastic H2O2, higher transcript levels of genes involved in polyamine synthesis and oxidation, and higher activities of polyamine oxidation and antioxidant enzymes. The results showed that overexpression of MfSAMS1 promoted polyamine synthesis and oxidation, which in turn improved H2 O2 -induced antioxidant protection, as a result enhanced tolerance to freezing and chilling stress in transgenic plants. This is the first report demonstrating that SAMS plays an important role in plant tolerance to cold via up-regulating polyamine oxidation.

  20. Accumulation of the hormone abscisic acid (ABA) at the infection site of the fungus Cercospora beticola supports the role of ABA as a repressor of plant defence in sugar beet.

    Science.gov (United States)

    Schmidt, Klaus; Pflugmacher, Maike; Klages, Simone; Mäser, Anja; Mock, Andrea; Stahl, Dietmar J

    2008-09-01

    Inducible plant defence responses in sugar beet (Beta vulgaris L.) leaves are repressed during the early phase of infection by the fungus Cercospora beticola. In this report, we show that the concentration of the plant hormone abscisic acid (ABA) increases in sugar beet leaves during C. beticola infection. After an initial burst of ABA induced by inoculation of the fungus, elevated ABA concentrations were detected during the fungal penetration and colonization phases 3-9 days after inoculation. Fifteen days after inoculation, with visible onset of the necrotic phase of infection, the strongly elevated ABA concentrations in infected leaves were at levels similar to drought-stressed plants. A synthetic promoter composed of four copies of the ABA-responsive element (ABRE) A2 and the coupling element CE3 of the ABA-inducible barley gene HVA1 was strongly induced by ABA and C. beticola infection in transgenic sugar beet leaves. Analysis of the spatial pattern of promoter activity revealed that the ABA-inducible promoter was locally activated at the fungal infection sites. Furthermore, expression of the basic leucine zipper transcription factor AREB1 was induced by drought stress and fungal infection in the sugar beet. Application of ABA reduced the promoter activity of the phenylalanine ammonia lyase (BvPAL) gene, and this effect was observed with the -34 to +248 BvPAL promoter region. This region is equivalent to the core promoter, which is necessary for the suppression of BvPAL expression by C. beticola, as recently shown. These data indicate that ABA accumulation and activation of the ABA-dependent signalling cascade are the primary cause of suppression of BvPAL expression during infection of sugar beet leaves.

  1. Ethylene and Abscisic Acid Signaling Pathways Differentially Influence Tomato Resistance to Combined Powdery Mildew and Salt Stress

    Science.gov (United States)

    Kissoudis, Christos; Seifi, Alireza; Yan, Zhe; Islam, A. T. M. Tanjimul; van der Schoot, Hanneke; van de Wiel, Clemens C. M.; Visser, Richard G. F.; van der Linden, C. G.; Bai, Yuling

    2017-01-01

    There is currently limited knowledge on the role of hormones in plants responses to combinations of abiotic and pathogen stress factors. This study focused on the response of tomato near-isogenic lines (NILs) that carry the Ol-1, ol-2, and Ol-4 loci, conferring resistance to tomato powdery mildew (PM) caused by Oidium neolycopersici, to combined PM and salt stress. These NILs were crossed with the notabilis (ABA-deficient), defenceless1 (JA-deficient), and epinastic (ET overproducer) tomato mutants to investigate possible roles of hormone signaling in response to combined stresses. In the NILs, marker genes for hormonal pathways showed differential expression patterns upon PM infection. The epinastic mutation resulted in breakdown of resistance in NIL-Ol-1 and NIL-ol-2. This was accompanied by reduced callose deposition, and was more pronounced under combined salt stress. The notabilis mutation resulted in H2O2 overproduction and reduced susceptibility to PM in NIL-Ol-1 under combined stress, but lead to higher plant growth reduction under salinity and combined stress. Resistance in NIL-ol-2 was compromised by the notabilis mutation, which was potentially caused by reduction of callose deposition. Under combined stress the compromised resistance in NIL-ol-2 was restored. PM resistance in NIL-Ol-4 remained robust across all mutant and treatment combinations. Hormone signaling is critical to the response to combined stress and PM, in terms of resistance and plant fitness. ABA appears to be at the crossroads of disease susceptibility/senescence and plant performance under combined stress These gained insights can aid in narrowing down targets for improving crop performance under stress combinations. PMID:28119708

  2. Defective chloroplast development inhibits maintenance of normal levels of abscisic acid in a mutant of the Arabidopsis RH3 DEAD-box protein during early post-germination growth.

    Science.gov (United States)

    Lee, Kwang-Hee; Park, Jiyoung; Williams, Donna S; Xiong, Yuqing; Hwang, Inhwan; Kang, Byung-Ho

    2013-03-01

    The plastid has its own translation system, and its ribosomes are assembled through a complex process in which rRNA precursors are processed and ribosomal proteins are inserted into the rRNA backbone. DEAD-box proteins have been shown to play roles in multiple steps in ribosome biogenesis. To investigate the cellular and physiological roles of an Arabidopsis DEAD-box protein, RH3, we examined its expression and localization and the phenotypes of rh3-4, a T-DNA insertion mutant allele of RH3. The promoter activity of RH3 is strongest in the greening tissues of 3-day and 1-week-old seedlings but reduced afterwards. Cotyledons were pale and seedling growth was retarded in the mutant. The most obvious abnormality in the mutant chloroplasts was their lack of normal ribosomes. Electron tomography analysis indicated that ribosome density in the 3-day-old mutant chloroplasts is only 20% that of wild-type chloroplasts, and the ribosomes in the mutant are smaller. These chloroplast defects in rh3-4 were alleviated in 2-week-old cotyledons and true leaves. Interestingly, rh3-4 seedlings have lower amounts of abscisic acid prior to recovery of their chloroplasts, and were more sensitive to abiotic stresses. Transcriptomic analysis indicated that nuclear genes for chloroplast proteins are down-regulated, and proteins mediating chloroplast-localized steps of abscisic acid biosynthesis are expressed to a lower extent in 1-week-old rh3-4 seedlings. Taken together, these results suggest that conversion of eoplasts into chloroplasts in young seedlings is critical for the seedlings to start carbon fixation as well as for maintenance of abscisic acid levels for responding to environmental challenges.

  3. Modulation of Root Signals in Relation to Stomatal Sensitivity to Root-sourced Abscisic Acid in Drought-affected Plants

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Stomatal sensitivity to root signals induced by soil drying may vary between environments and plant species. This is likely central role in root to shoot signaling. pH and hydraulic signals may interact with ABA signals and thus, jointly regulate stomatal responses to changed soil water status. pH itself can be modified by several factors, among which the chemical compositions In the xylem stream and the live cells surrounding the vessels play crucial roles. In addition to the xylem pH,more attention should be paid to the direct modulation of leaf apoplastic pH, because many chemical compositions might strongly modify the leaf apoplastlc pH while having no significant effect on the xylem pH. The direct modulation of the ABA signal intensity may be more important for the regulation of stomatal responses to soil drying than the ABA signal per se.The ABA signal is also regulated by the ABA catabolism and the supply of precursors to the roots If a sustained root to shoot communication of soil drying operates at the whole plant level. More importantly, ABA catabolism could play crucial roles In the determination of the fate of the ABA signal and thereby control the stomatal behavior of the root-sourced ABA signal.

  4. AtRH57, a DEAD-box RNA helicase, is involved in feedback inhibition of glucose-mediated abscisic acid accumulation during seedling development and additively affects pre-ribosomal RNA processing with high glucose.

    Science.gov (United States)

    Hsu, Yi-Feng; Chen, Yun-Chu; Hsiao, Yu-Chun; Wang, Bing-Jyun; Lin, Shih-Yun; Cheng, Wan-Hsing; Jauh, Guang-Yuh; Harada, John J; Wang, Co-Shine

    2014-01-01

    The Arabidopsis thaliana T-DNA insertion mutant rh57-1 exhibited hypersensitivity to glucose (Glc) and abscisic acid (ABA). The other two rh57 mutants also showed Glc hypersensitivity similar to rh57-1, strongly suggesting that the Glc-hypersensitive feature of these mutants results from mutation of AtRH57. rh57-1 and rh57-3 displayed severely impaired seedling growth when grown in Glc concentrations higher than 3%. The gene, AtRH57 (At3g09720), was expressed in all Arabidopsis organs and its transcript was significantly induced by ABA, high Glc and salt. The new AtRH57 belongs to class II DEAD-box RNA helicase gene family. Transient expression of AtRH57-EGFP (enhanced green fluorescent protein) in onion cells indicated that AtRH57 was localized in the nucleus and nucleolus. Purified AtRH57-His protein was shown to unwind double-stranded RNA independent of ATP in vitro. The ABA biosynthesis inhibitor fluridone profoundly redeemed seedling growth arrest mediated by sugar. rh57-1 showed increased ABA levels when exposed to high Glc. Quantitative real time polymerase chain reaction analysis showed that AtRH57 acts in a signaling network downstream of HXK1. A feedback inhibition of ABA accumulation mediated by AtRH57 exists within the sugar-mediated ABA signaling. AtRH57 mutation and high Glc conditions additively caused a severe defect in small ribosomal subunit formation. The accumulation of abnormal pre-rRNA and resistance to protein synthesis-related antibiotics were observed in rh57 mutants and in the wild-type Col-0 under high Glc conditions. These results suggested that AtRH57 plays an important role in rRNA biogenesis in Arabidopsis and participates in response to sugar involving Glc- and ABA signaling during germination and seedling growth.

  5. Expression analysis of abscisic acid (ABA) and metabolic signalling factors in developing endosperm and embryo of barley.

    Science.gov (United States)

    Chen, Zhiwei; Huang, Jianhua; Muttucumaru, Nira; Powers, Stephen J; Halford, Nigel G

    2013-09-01

    The expression of genes encoding components of ABA and metabolic signalling pathways in developing barley endosperm and embryo was investigated. The genes included HvRCAR35_47387 and HvRCAR35_2538 (encoding ABA receptors), HvABI1d (protein phosphatase 2C), HvSnRK2.4, HvSnRK2.6 and HvPKABA1 (SnRK2-type protein kinases) and HvABI5 (ABA response element binding protein; AREBP), as well as two genes encoding SnRK1-type protein kinases. Both SnRK1 and SnRK2 phosphorylate AREBPs, but SnRK2 is activated by ABA whereas SnRK1 may be broken down. Multiple cereal AREBPs with two conserved SnRK1/2 target sites and another class of BZIP transcription factors with SnRK1/2 binding sites, including HvBLZ1, were identified. Barley grain (cv. Triumph) was sampled at 15, 20, 25 and 30 days post-anthesis (dpa). HvRCAR35_47387, HvABI1d, HvSnRK2.4 and HvABI5 were expressed highly in the endosperm but at much lower levels in the embryo. Conversely, HvPKABA1 and HvRCAR35_2538 were expressed at higher levels in the embryo than the endosperm, while HvSnRK2.6 was expressed at similar levels in both. HvRCAR35_47387, HvABI1d, HvSnRK2.4 and HvABI5 all peaked in expression in the endosperm at 20 dpa. A model is proposed in which ABA brings about a transition from a SnRK1-dominated state in the endosperm during grain filling to a SnRK2-dominated state during maturation.

  6. Expression analysis of abscisic acid (ABA) and metabolic signalling factors in developing endosperm and embryo of barley☆

    Science.gov (United States)

    Chen, Zhiwei; Huang, Jianhua; Muttucumaru, Nira; Powers, Stephen J.; Halford, Nigel G.

    2013-01-01

    The expression of genes encoding components of ABA and metabolic signalling pathways in developing barley endosperm and embryo was investigated. The genes included HvRCAR35_47387 and HvRCAR35_2538 (encoding ABA receptors), HvABI1d (protein phosphatase 2C), HvSnRK2.4, HvSnRK2.6 and HvPKABA1 (SnRK2-type protein kinases) and HvABI5 (ABA response element binding protein; AREBP), as well as two genes encoding SnRK1-type protein kinases. Both SnRK1 and SnRK2 phosphorylate AREBPs, but SnRK2 is activated by ABA whereas SnRK1 may be broken down. Multiple cereal AREBPs with two conserved SnRK1/2 target sites and another class of BZIP transcription factors with SnRK1/2 binding sites, including HvBLZ1, were identified. Barley grain (cv. Triumph) was sampled at 15, 20, 25 and 30 days post-anthesis (dpa). HvRCAR35_47387, HvABI1d, HvSnRK2.4 and HvABI5 were expressed highly in the endosperm but at much lower levels in the embryo. Conversely, HvPKABA1 and HvRCAR35_2538 were expressed at higher levels in the embryo than the endosperm, while HvSnRK2.6 was expressed at similar levels in both. HvRCAR35_47387, HvABI1d, HvSnRK2.4 and HvABI5 all peaked in expression in the endosperm at 20 dpa. A model is proposed in which ABA brings about a transition from a SnRK1-dominated state in the endosperm during grain filling to a SnRK2-dominated state during maturation. PMID:24748715

  7. 脱落酸抗代谢与光稳定性类似物研究进展%Research Advances in Antimetabolic and Photostable Analogues of Abscisic Acid

    Institute of Scientific and Technical Information of China (English)

    韩小强; 肖玉梅; 路慧哲; 覃兆海

    2013-01-01

    脱落酸是一种广泛存在于植物体内的抑制性植物激素,具有诱导种子休眠、抑制种子萌发、控制气孔关闭和增强植物抗逆性等生物活性,在植物生长发育的各个阶段起着独特而重要的生理作用.但是较高的生产成本、在植物体内快速代谢失活和侧链2-位顺式双键的光异构化失活限制了脱落酸在农业生产中的应用.因此,合成并筛选出活性更高、更稳定的脱落酸类似物,是备受关注的研究领域.该文综述了脱落酸抗代谢与光稳定性研究的新进展,介绍了脱落酸抗代谢与光稳定性类似物研究中存在的问题并对今后的研究方向进行了展望.%Abscisic acid is an important phytohormone that has many functions in higher plants,including seed germination,development and dormancy; regulating stomatal movement; and improving stress tolerance.However,two major drawbacks have restricted its application as a plant growth regulator for agrochemical use:It is easily metabolized in plants and this leads to concomitant loss of biological activity and geometry (2Z,4E) of its 2,4-pentadienoic acid moiety,which is crucial for its hormonal activities to be readily isomerized to biologically inactive (2E,4E) isomers by light.Accordingly,synthesis of new abscisic acid analogues with higher activity and better photo-stability is important.This paper reviews research advances in the chemical and biological activities of antimetabolic and photostable analogs of abscisic acid.

  8. 光敏色素B介导光信号影响水稻的脱落酸途径%Light signals mediated by phytochrome B affect abscisic acid pathway in rice

    Institute of Scientific and Technical Information of China (English)

    顾建伟; 张方; 赵杰; 周晋军; 钱凤芹; 闫丽华; 臧新; 谢先芝

    2012-01-01

    Several evidences revealed the interaction between phytochrome-mediated light signals and plant hormones abscisic acid (ABA) pathway in Arabidopsis. However, interaction between ABA signaling and phytochrome-mediated light signaling in mediating rice growth and development remain unclear. In the present study, we analyzed effects of P/nB-mediated light signals on ABA metabolism and ABA responses using rice wild type (WT) and the phyB mutant. It was observed that transcript levels of ABA biosynthetic genes (including OsNCEDl, 0sNCED2, OsNCED3 and 0sNCED4) were higher in the phyB mutant than those in WT, whereas transcript level of ABA deactivating gene OsABA8OXl was lower in the phyB mutant than that in WT, which probably contributed to the relatively high ABA content in the phyB mutant. ABA treatment inhibited germination of rice seeds grown either in the dark or under light. However, inhibitory effects of ABA treatment on seed germination were more obvious in phyB mutants relative to that in WT when seeds were grown under light conditions, suggesting that PhyB-mediated light signals attenuated the inhibitory effects triggered by ABA. Meantime, we compared the expression patterns of genes related to seed germination in WT and the phyB mutant grown in the medium with or without ABA. It was deduced that these genes is unlikely to contribute for the promotive effects of phyB-mediated light signals on seed germination. In addition, ABA treatment inhibited growth of both above-ground part and seminal root in rice seedlings. PhyB-mediated light signals did not affect the ABA-induced inhibition of above-ground part growth, but negatively regulate the inhibition of root growth. Taken together, our results suggest that PhyB-mediated light signals negatively regulate ABA accumulation and ABA responses in rice. This work reveals the influence of PhyB-mediated light signals on ABA pathway, which lays the foundation for dissecting the molecular mechanism of coordinated

  9. 脱落酸抑制剂氟啶酮对小鼠弓形虫病的影响%Effect on the inhibitor for abscisic acid fluridone on infection of Toxoplasma gondii in mice

    Institute of Scientific and Technical Information of China (English)

    孔璟; 叶彬; 武卫华

    2012-01-01

    目的 观察脱落酸抑制剂氟啶酮对小鼠弓形虫病的影响.方法 给感染弓形虫RH株的小鼠腹腔注射氟啶酮,观察小鼠生存延长率、体重变化;光镜及电镜观察腹腔中弓形虫形态;脏器组织印片评估体内弓形虫扩散情况.结果 与对照组相比,氟啶酮治疗的小鼠弓形虫病症状出现晚且程度较轻,生存时间延长(P<0.05),生存延长率为45%,体重减少率为6.13%,而对照组体重减少率为7.23%;对照组小鼠腹腔中以游离速殖子为主,实验组则以细胞内虫体为主;实验组小鼠脏器受虫体累及的时间稍晚,感染程度也比对照组轻.结论 氟啶酮能对小鼠弓形虫病起抑制作用.%To investigate the effect of fluridone, an inhibitor of abscisic acid, on mice infected with Toxoplasma gondii (T. gondii) RH strain, the mice infected with T. gondii were treated with fluridone by intraperitoneal injection in order to observe the survival time and the weight reduction rate of them. The modality of T. gondii in the intraperitoneal cavity of mice was observed by microscope and electron microscope, and the irradiation of T. gondii was evaluated by tissue printing. The symptom of toxoplasmosis in the group treated with fluridone appeared later and milder than those in the control group. The survival duration was longer (P<0. 05) and the extension rate was 45%. The weight inhibitory rate of the treated mice was 6. 13% , whereas that was 7. 23% in the control mice. T. gondii in the control group were tachyzoites mainly, but intracellular parasite in mice was treated with fluridone. Destroy in organs happened later in the mice infected with T. gondii and the degree of infection was milder than in the control. These results suggested that fluridone could inhibit toxoplasmosis in mice, which were related to the function of blocking T. gondii egress and inducing development on vacuoles of intracellular by inhibiting abscisic acid.

  10. Desiccation and zinc binding induce transition of tomato abscisic acid stress ripening 1, a water stress- and salt stress-regulated plant-specific protein, from unfolded to folded state.

    Science.gov (United States)

    Goldgur, Yehuda; Rom, Slava; Ghirlando, Rodolfo; Shkolnik, Doron; Shadrin, Natalia; Konrad, Zvia; Bar-Zvi, Dudy

    2007-02-01

    Abscisic acid stress ripening 1 (ASR1) is a low molecular weight plant-specific protein encoded by an abiotic stress-regulated gene. Overexpression of ASR1 in transgenic plants increases their salt tolerance. The ASR1 protein possesses a zinc-dependent DNA-binding activity. The DNA-binding site was mapped to the central part of the polypeptide using truncated forms of the protein. Two additional zinc-binding sites were shown to be localized at the amino terminus of the polypeptide. ASR1 protein is presumed to be an intrinsically unstructured protein using a number of prediction algorithms. The degree of order of ASR1 was determined experimentally using nontagged recombinant protein expressed in Escherichia coli and purified to homogeneity. Purified ASR1 was shown to be unfolded using dynamic light scattering, gel filtration, microcalorimetry, circular dichroism, and Fourier transform infrared spectrometry. The protein was shown to be monomeric by analytical ultracentrifugation. Addition of zinc ions resulted in a global change in ASR1 structure from monomer to homodimer. Upon binding of zinc ions, the protein becomes ordered as shown by Fourier transform infrared spectrometry and microcalorimetry, concomitant with dimerization. Tomato (Solanum lycopersicum) leaf soluble ASR1 is unstructured in the absence of added zinc and gains structure upon binding of the metal ion. The effect of zinc binding on ASR1 folding and dimerization is discussed.

  11. Disease resistance or growth: the role of plant hormones in balancing immune responses and fitness costs

    NARCIS (Netherlands)

    Denance, N.; Sanchez Vallet, A.; Goffner, D.; Molina, A.

    2013-01-01

    Plant growth and response to environmental cues are largely governed by phytohormones. The plant hormones ethylene, jasmonic acid, and salicylic acid (SA) play a central role in the regulation of plant immune responses. In addition, other plant hormones, such as auxins, abscisic acid (ABA), cytokini

  12. Abscisic acid and aldehyde oxidase activity in maize ear leaf and grain relative to post-flowering photosynthetic capacity and grain-filling rate under different water/nitrogen treatments.

    Science.gov (United States)

    Qin, Shujun; Zhang, Zongzheng; Ning, Tangyuan; Ren, Shizhong; Su, Licheng; Li, Zengjia

    2013-09-01

    This study investigated changes in leaf abscisic acid (ABA) concentrations and grain ABA concentrations in two maize cultivars and analyzed the following relationships under different water/nitrogen treatments: leaf ABA concentrations and photosynthetic parameters; leaf ABA concentrations and grain ABA concentrations; leaf/grain ABA concentrations and grain-filling parameters; and aldehyde oxidase (AO, EC 1.2.3.1) activities and ABA concentrations. The ear leaf average AO activities and ABA concentrations were lower in the controlled release urea treatments compared with the conventional urea treatments. The average AO activities in the grains were higher in the controlled release urea treatments, and the ABA concentrations were significantly increased at 11-30 DAF. The Pn and ABA concentrations in ear leaves were negatively correlated. And the Gmean were positively correlated with the grain ABA concentrations at 11-30 DAF and negatively correlated with the leaf ABA concentrations at 20 and 40-50 DAF. The grain ABA concentrations and leaf ABA concentrations were positively correlated. Thus, the Gmean were closely related to the AO activities and to the ear leaf and grain ABA concentrations. As compared to other treatments, the subsoiling and controlled release urea treatment promoted the uptake of water and nitrogen by maize, increased the photosynthetic capacity of the ear leaves, increased the grain-filling rate, and improved the movement of photosynthetic assimilates toward the developing grains. In the cultivar Z958, higher ABA concentrations in grains at 11-30 DAF and lower ABA concentrations in ear leaves during the late grain-filling stage, resulted in higher grain-filling rate and increased accumulation of photosynthetic products (relative to the cultivar D3).

  13. Cloning of 9-cis-epoxycarotenoid dioxygenase (NCED) gene encoding a key enzyme during abscisic acid (ABA) biosynthesis and ABA-regulated ethylene production in detached young persimmon calyx

    Institute of Scientific and Technical Information of China (English)

    LENG Ping; ZHANG GuangLian; LI XiangXin; WANG LiangHe; ZHENG ZhongMing

    2009-01-01

    Unlike the typical climacteric fruits,persimmons (Diospyros kaki Thunb.) produce higher levels of ethylene when they are detached from trees at a younger stage.In order to obtain detailed information on the role of abscisic acid (ABA) in ripening,we cloned the DKNCED1,DKACS2,and DKAC01 genes from the calyx.Water loss was first noted in the calyx lobe,and DKNCED1 was highly expressed 1 d after the fruits were detached,coinciding with an increase in the ABA content.Then,the DKACS2 and DKAC01 genes were expressed after some delay.In the calyx,the ABA peak was observed 2 d after the fruits were harvested,and this peak preceded the ethylene peak observed on day 3.The fruit firmness rapidly decreased on day 4,and the fruits softened completely 6 d after they were harvested.The increases in the expressions of ABA,ethylene,and the genes in the calyxes occurred earlier than the corresponding increases in the pulp,although the 3 increases occurred on different days.Exogenous ABA treatment increased ABA concentration,induced expression of both ACS and ACO,and promoted ethylene synthesis and young-fruit softening;by contrast,treatment with NDGA inhibited the gene expressions and ethylene synthesis and delayed young-fruit softening.These results indicate that ethylene biosynthesis in the detached young persimmon fruits is initially triggered by ABA,which is induced by water loss in the calyx,through the induction of DKACS2 and DKAC01 expressions.The ethylene produced in the calyx subsequently diffuses into the pulp tissue,where it induces autocatalytic ethylene biosynthesis,resulting in an abrupt increase in ethylene production.

  14. 脱落酸、水杨酸和钙对黄瓜幼苗抗冷性的诱导效应%Inductive Effect of Abscisic Acid, Salicylic Acid, and Calcium on Cold Resistance of Cucumber Seedlings

    Institute of Scientific and Technical Information of China (English)

    杨楠; 刘培培; 白小梅; 徐坤范; 艾希珍

    2012-01-01

    The purpose of this paper is to investigate the effect and its mechanism of abscisic acid (ABA), salicylic acid (SA) and calcium chloride (CaCl2) on cold resistance of cucumber (Cucumis sativus L. ) seedlings. Cucumber ( cv. Jinyou 35) seedlings pretreated with a foliar spray of 0.1 mmol · L-1 ABA, 1 mmol · L-1 SA, 10 mmol · L-1 CaCl2, or distilled water (control) were displaced into growth chambers and treated under low temperature (day/night temperature is 8 °C/ 5 °C). The results revealed that low temperature stress significantly increased the chilling injury index, electrolyte leakage (EL), contents of malondialdehyde (MDA) and hydrogen peroxide (H2O2). The peroxidase(POD) activity increased gradually with stress time, whereas, activities of superoxide dismutase (SOD) , catalase (CAT) , and glutathione reducase(GR) increased at first and reduced later. The contents of proline and soluble sugar enhanced remarkably with stress time. Pretreated with ABA, SA or CaCl2 before exposure to stress condition, the cold injury indexes of cucumber seedlings decreased by 50. 0%, 40. 0% and 47. 1%, respectively. ABA, SA and CaCl2 treatment seedlings showed significant lower increase degree in EL and MDA content compared with control seedlings. At the initial stress stage, the increase degree of H2O2 content in ABA, SA and CaCl2 treatment seedlings were higher than that of control, but the H2O2 content in ABA, SA and CaCl2 treatment seedlings trend to reduction after 24 h, and were lower by 27. 9%, 27. 5% and 34. 4% respectively at 72 h, compared with that of control. The ABA, SA and CaCl2 treatment seedlings showed significant higher antioxidase activity and contents of proline and soluble sugar than those of control. These data suggest that ABA, SA and CaCl2 can induce cold resistance in cucumber seedlings, and the inductive effect may be related to the observed increase in antioxidase activity and osmoregulation capability.%为了探明脱落酸(ABA)、

  15. Spatio-temporal appearance of α-amylase and limit dextrinase in barley aleurone layer in response to gibberellic acid, abscisic acid and salicylic acid

    DEFF Research Database (Denmark)

    Shahpiri, Azar; Talaei, Nasim; Finnie, Christine

    2015-01-01

    Release of LD was found to differ from that of amylase and was suggested to depend on programmed cell death (PCD). Despite detection of intracellular amylase in untreated aleurone layers or aleurone layers treated with ABA or SA, α-amylase was not released from these samples. Nevertheless, the re...

  16. Abscisic Acid-Induced H2O2 Accumulation Enhances Antioxidant Capacity in Pumpkin-Grafted Cucumber Leaves under Ca(NO3)2 Stress

    Science.gov (United States)

    Shu, Sheng; Gao, Pan; Li, Lin; Yuan, Yinghui; Sun, Jin; Guo, Shirong

    2016-01-01

    With the aim to clarifying the role of the ABA/H2O2 signaling cascade in the regulating the antioxidant capacity of grafted cucumber plants in response to Ca(NO3)2 stress, we investigated the relationship between ABA-mediated H2O2 production and the activities of antioxidant enzymes in the leaves of pumpkin-grafted cucumber seedlings. The results showed that both ABA and H2O2 were detected in pumpkin-grafted cucumber seedlings in response to Ca(NO3)2 treatment within 0.5 h in the leaves and peaked at 3 and 6 h after Ca(NO3)2 treatment, respectively, compared to the levels under control conditions. The activities of superoxide dismutase (SOD), ascorbate peroxidase (APX), and peroxidase (POD) in pumpkin-grafted cucumber leaves gradually increased over time and peaked at 12 h of Ca(NO3)2 stress. Furthermore, in the leaves of pumpkin-grafted cucumber seedlings, the H2O2 generation, the antioxidant enzyme activities and the expression of SOD, POD and cAPX were strongly blocked by an inhibitor of ABA under Ca(NO3)2 stress, but this effect was eliminated by the addition of exogenous ABA. Moreover, the activities and gene expressions of these antioxidant enzymes in pumpkin-grafted leaves were almost inhibited under Ca(NO3)2 stress by pretreatment with ROS scavengers. These results suggest that the pumpkin grafting-induced ABA accumulation mediated H2O2 generation, resulting in the induction of antioxidant defense systems in leaves exposed to Ca(NO3)2 stress in the ABA/H2O2 signaling pathway. PMID:27746808

  17. Folinic acid-responsive seizures initially responsive to pyridoxine.

    Science.gov (United States)

    Nicolai, Joost; van Kranen-Mastenbroek, Vivianne H J M; Wevers, Ron A; Hurkx, Wilfred A P T; Vles, Johan S H

    2006-02-01

    This report presents a male who developed clonic seizures on the day he was born. The next day, the diagnosis of pyridoxine-dependent seizures was made. However, contradictory to this diagnosis, seizures reappeared despite treatment with pyridoxine. Seizures ceased after folinic acid was initiated. The clinical and biochemical characteristics of folinic acid-responsive seizures are reviewed. Treatment with folinic acid should be considered in neonatal seizures of unknown origin that do not respond to pyridoxine, or manifest a transient response to pyridoxine.

  18. RBSDV 侵染对水稻 ABA 代谢相关基因表达的影响%Effect of RBSDV Infection on Transcriptional Expression of Abscisic Acid Metabolism Related Genes in Rice

    Institute of Scientific and Technical Information of China (English)

    倪海平; 徐秋芳; 兰莹; 陈晴晴; 张金凤; 周益军

    2015-01-01

    为明确水稻黑条矮缩病毒(Rice black streaked dwarf virus ,RBSDV)侵染对水稻脱落酸(abscisic acid,ABA)含量的影响,通过灰飞虱在水稻日本晴和淮稻5号两个品种上人工接种 RBSDV,待接种的水稻表现明显矮缩症状时,采用 ELISA方法测定 ABA 含量.结果显示,在接种 RBSDV 的日本晴和淮稻5号中,ABA 含量均明显增加.接种病毒的日本晴植株中ABA 含量为111.04 ng/g,而对照中仅为60.86 ng/g;淮稻5号对照植物 ABA 含量为70.61 ng/g,而病株中 ABA 的含量为102.60 ng/g.为进一步明确病毒侵染如何调控 ABA 的含量,采用荧光定量 PCR 方法分析了日本晴接种 RBSDV 8 d,12 d,16 d 和60 d 时 ABA 合成关键基因(OsZEP 、OsNCED1、OsNCED2、OsNCED3、OsNCED4和 OsNCED5)及分解关键基因(OsABA8ox1、OsABA8ox2和 OsABA8ox3)mRNA 相对表达量的变化.结果显示,病毒侵染8 d,ABA 合成和分解代谢基因的表达量均高于对照,其中 OsNCED4和 OsNCED5的表达量随病毒侵染时间的延长而增加,至60 d 时 OsNCED3、OsNCED4和 OsNCED5的表达量为对照的3.97、7.66和2.99倍,而 OsZEP ,OsABA8ox1和 OsABA8ox2的表达量则随侵染时间的延长而降低.RBSDV 侵染后可能既影响了 ABA 合成也影响了其分解,两者共同作用导致了 ABA 含量增加.%To investigate the effect of virus infection on abscisic acid (ABA)content in rice,two rice varieties, Nipponbare and Huaidao 5 ,were inoculated with rice black streaked dwarf virus (RBSDV)artificially via small brown planthoppers,and the ABA content was measured by ELISA method when the plants showed the obvious viral disease symptoms.The results showed that the ABA content was increased in virus infected rice.The ABA content in virus infected Nipponbare was 1 1 1 .04 ng/g compared to 60.86 ng/g in the control.In Huaidao 5 ,it was 102.60 ng/g in the virus infected plants and 70.6 1 ng/g in the control.To reveal how the virus regulates the ABA content,the relative

  19. EL ÁCIDO ABSCÍSICO ACELERA EL DESARROLLO FLORAL DE SOLIDAGO EN DÍAS CORTOS ABSCISIC ACID SPEED UP FLORAL DEVELOPMENT OF SOLIDAGO UNDER SHORT DAYS

    Directory of Open Access Journals (Sweden)

    Víctor Julio Flórez Roncancio

    2009-06-01

    Full Text Available Solidago x luteus (M. L. Greene Broulliet y Semple (= x Solidaster hybridus, x S. luteus es una planta que responde a días cortos (DC para el desarrollo floral. En este proceso se ha establecido la participación de varias fitohormonas, entre éstas, la presencia del ácido abscísico (ABA en zonas y periodos específicos durante el desarrollo de la flor lo cual sugiere su acción promotora en la velocidad de antesis floral de esta especie en DC. En este trabajo se buscaron nuevos indicios de la participación de fitohormonas presentes en la fracción ácida con el proceso de floración. En una primera etapa, extractos foliares provenientes de hojas de plantas en días largos (caracterizadas por menor velocidad de antesis floral se aplicaron en botones florales de plantas en días cortos (caracterizadas por una mayor velocidad de antesis floral. Se realizaron ocho aplicaciones con diferentes frecuencias totalizando un periodo de tratamiento de 25 días. Los resultados mostraron que las sustancias presentes en los extractos de la fracción ácida, no alteran la velocidad promedio de antesis floral en los botones florales de plantas en DC. En la segunda etapa del experimento, la cuantificación de los extractos por ELISA, permitió establecer una mayor concentración de ABA en los extractos de hojas y de botones florales de plantas en DC y de botones florales en el inicio del tratamiento. Estos resultados confirman la relación del ABA con la mayor velocidad de antesis floral en plantas de Solidago x luteus en condiciones de DC.Solidago x luteus (M.L. Greene Broulliet & Semple (= x Solidaster hybridus, x S. luteus is a plant that respond to short days (SD for flower development. In this process, there has been established the involvement of many phytohormones, between these, the presence of the abscisic acid (ABA in zones and specific periods during flower development, suggests its promoter roll on the floral anthesis period of this species under

  20. Citraturic response to oral citric acid load

    Science.gov (United States)

    Sakhaee, K.; Alpern, R.; Poindexter, J.; Pak, C. Y.

    1992-01-01

    It is possible that some orally administered citrate may appear in urine by escaping oxidation in vivo. To determine whether this mechanism contributes to the citraturic response to potassium citrate, we measured serum and urinary citrate for 4 hours after a single oral load of citric acid (40 mEq.) in 6 normal subjects. Since citric acid does not alter acid-base balance, the effect of absorbed citrate could be isolated from that of alkali load. Serum citrate concentration increased significantly (p less than 0.05) 30 minutes after a single oral dose of citric acid and remained significantly elevated for 3 hours after citric acid load. Commensurate with this change, urinary citrate excretion peaked at 2 hours and gradually decreased during the next 2 hours after citric acid load. In contrast, serum and urinary citrate remained unaltered following the control load (no drug). Differences of the citratemic and citraturic effects between phases were significant (p less than 0.05) at 2 and 3 hours. Urinary pH, carbon dioxide pressure, bicarbonate, total carbon dioxide and ammonium did not change at any time after citric acid load, and did not differ between the 2 phases. No significant difference was noted in serum electrolytes, arterialized venous pH and carbon dioxide pressure at any time after citric acid load and between the 2 phases. Thus, the citraturic and citratemic effects of oral citric acid are largely accountable by provision of absorbed citrate, which has escaped in vivo degradation.

  1. The Decomposition Process of Abscisic Acid in Soils from Evergreen Broadleaf Forest in Xiaokeng, Nanling%南岭小坑常绿阔叶林土壤脱落酸分解特征

    Institute of Scientific and Technical Information of China (English)

    陈传胜; 黄从军; 赵厚本; 周光益; 邱治军; 梁瑞友

    2015-01-01

    Abscisic acid (ABA), a hormone synthesized by plants, can enter the soil solution and affect plant growth, seed germination, community composition and succession. Understanding the decomposition process of ABA in soil can help us to reveal the circulation of ABA in soils and its implication on plant growth. Soils were collected from an evergreen broadleaf forest in Xiaokeng, Nanling moutians, and soil physical and chemical properties and ABA concentration were measured. Additionally, an incubation experiment was conducted to measure soil ABA decomposition rate and the role of soil microorganism play in this process. Results showed that the concentration of ABA in soil solution was heterogeneous in space ranging from 29.8 ng·mL-1 to 167.0 ng·mL-1 (averaged at 91.5 ng·mL-1), and positively correlated with soil total nitrogen. About 33.5%of soil ABA was quickly decomposed by soil microorganisms during the first week of incubation, and then was decomposed slowly and linearly with a decomposition rate of about 0.24% per day afterwards. Soil ABA concentration and decomposition rate was positively correlated during the initial fast-decomposition period but was negatively correlated at the late slow-decomposition period. Soil microorganisms accelerated ABA decomposition on one hand and avoided the depletion of ABA in soil on the other hand.%植物产生的脱落酸(ABA)可进入土壤并在土壤溶液中保持一定浓度,对植物生长、种子萌发、群落组成和演替具有重要意义。研究土壤ABA的分解过程有助于了解ABA在土壤中的循环过程,揭示土壤ABA和植物生长的相互关系。以广东南岭小坑常绿阔叶林为研究对像,分析了土壤理化性质和土壤ABA质量浓度的关系,并通过室内培养法结合灭菌处理研究土壤ABA的分解过程和土壤微生物在ABA分解过程中的作用。结果表明,土壤ABA质量浓度在29.8~167.0 ng·mL-1间,均值为91.5 ng·mL-1,且存在较大的

  2. Response of agricultural soils to acid deposition

    Energy Technology Data Exchange (ETDEWEB)

    Arthur, M.F.; Wagner, C.K.

    1982-07-01

    Proceedings of the workshop, Response of Agricultural Soils to Acid Deposition, which was held May 12-13 1981, in Columbus, Ohio, and which evaluated the potential beneficial and harmful impacts of atmospheric acid deposition on agricultural soils are presented. Those issues requiring further research are also identified. Five working papers and a literature review prepared by soils specialists are included as is a summary of conclusions reached by the participants. Each of the five working papers has been abstracted and indexed individually for ERA/EDB. (JGB)

  3. 拟南芥bZIP1转录因子通过与ABRE元件结合调节ABA信号传导%Arabidopisis bZIP1 Transcription Factor Binding to the ABRE Cis-Element Regulates Abscisic Acid Signal Transduction

    Institute of Scientific and Technical Information of China (English)

    孙晓丽; 李勇; 才华; 柏锡; 纪巍; 季佐军; 朱延明

    2011-01-01

    Abscisic acid (ABA) is a phytohormone and mediates the response and adaptation of higher plants to various environmental stresses during vegetative growth.The basic leucine zipper (bZIP) transcription factors are also important regulators of plant development and abiotic resistance, acting through either ABA-dependent or ABA-independent pathways.In this study, we investigated and characterized the involvement of the AtbZIP1 gene in plant responsiveness to ABA.As confirmed by PCR and RT-PCR, AtbZIP1 has been silenced in mutant Arabidopsis ko-1 (SALK_059343) and ko-2 (SALK_069489C).The AtbZIP1 knockout plants demonstrated reduced sensitivity to ABA both at the seed germination and seedling stage with improvements in rates of germination, leaf opening/greening, and primary root length.In order to investigate whether the regulation of AtbZIP1-mediated ABA responsiveness depended on the ABA-responsive elements (ABRE), we expressed the AtbZIP1 HIS6 fusion protein in E.coli and found that the AtbZIP1 HIS6 specifically bound to the ABRE cis-elements.Semi-quantitive RT PCR showed that AtbZIP1 disruption altered expressions of some ABA responsive genes, such as NCED3, RD22, KIN1, and RD29A.Our results indicated that AtbZIP1 regulates abscisic acid signal transduction by binding to the ABREs and altered the expressions of the ABA responsive genes.%ABA作为一种重要的植物激素和生长凋节剂,介导了高等植物在营养生长阶段对各种外界环境的响应和适应.bZIP类转录因子可以通过ABA依赖途径和ABA非依赖途径调节植物的生长发育和对非生物胁迫的耐性.本研究通过AtbZIP1 T-DNA插入突变的拟南芥植株ko-1(SALK_059343)和ko-2(SALK_069489C)在ABA处理后的表型实验,验证了AtbZIP1参与ABA依赖的信号传导通路.采用"三引物法",分别在DNA水平和RNA水平通过PCR和RT-PCR验证了AtbZIP1基因在拟南芥突变体中的沉默效果.定量分析数据表明,在种子萌发阶段,经过0.6μmolL-1

  4. The role of the HvNAC6 transcription factor in response to biotic and abiotic stress in barley

    DEFF Research Database (Denmark)

    Chen, Yan-Jun

    -mediated transformation methods could be used to study stress responses at the whole-plant level. The abscisic acid (ABA) and salicylic acid (SA) levels were measured during Bgh infection to investigate the involvement of these hormones and TF in the basal resistance. HvNAC6 RNAi plants were also subjected to dehydration...

  5. Folinic acid-responsive neonatal seizures.

    Science.gov (United States)

    Torres, O A; Miller, V S; Buist, N M; Hyland, K

    1999-08-01

    We report three cases of folinic acid-responsive intractable neonatal seizures. All patients were born at term following normal gestation and delivery. In the first infant, seizures began on the 5th day of life and were unresponsive to phenobarbital, pyridoxine, and valproate, but stopped within 24 hours of initiation of folinic acid treatment at the age of 6 months. Her sibling had died at age 6 months with intractable seizures. In the second infant, seizures began in the 2nd hour of life. These were initially controlled with phenobarbital; however, at 3 months of age she developed status epilepticus refractory to anticonvulsants, steroids, and pyridoxine and she required repeated induction of pentobarbital coma. Seizures stopped within 24 hours of starting folinic acid. Seizures and encephalopathy were noted in the third infant on the 2nd day of life. These were controlled with phenobarbital, but at 8 weeks of age seizures recurred and were difficult to control despite the addition of phenytoin. Immediately after folinic acid was initiated the seizures stopped. Breakthrough seizures in all patients have responded to increases in folinic acid; two of the three remain on standard anticonvulsants. All patients have global developmental delay. Cranial magnetic resonance imaging in the second patient shows diffuse atrophy, and in the third patient shows increased signal on T2 images in the white matter of the frontal and parietal lobes. Analysis of cerebrospinal fluid from these patients using high-performance liquid chromatography with electrochemical detection has consistently revealed an as-yet unidentified compound, which can be used as a marker for this condition. We suggest that cerebrospinal fluid be analyzed for the presence of this compound and a trial of folinic acid be considered in neonates with unexplained early onset intractable seizures.

  6. Analysis of the essential DNA region for OsEBP-89 promoter in response to methyl jasmonic acid

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    In rice, the characterization of OsEBP-89 is inducible by various stress- or hormone-stimuli, including ethylene, abscisic acid (ABA), jasmonate acid (JA), drought and cold. Here, we report the investigation of essential DNA region within OsEBP-89 promoter for methyl jasmonic acid (MeJA) induction. PLACE analysis indicates that this promoter sequence contains multiple potential elements in response to various stimuli. First, we fused this promoter with GUS gene and analyzed its expression under MeJA treatment through Agrobacterium infiltration mediating transient expression in tobacco leaves. Our results revealed that this chimeric gene could be inducible by MeJA in tobacco leaves. To further de- termine the crucial sequences responsible for MeJA induction, we generated a series of deletion pro- moters which were fused with GUS reporter gene respectively. The results of transient expression of GUS gene driven by these mutant promoters show that the essential region for MeJA induction is po- sitioned in the region between -1200 and -800 in OsEBP-89 promoter containing a G-box (?1127), which is distinct from the essential region containing ERE (?562) for ACC induction. In all, our finding is helpful in understanding the molecular mechanism of OsEBP-89 expression under different stimuli.

  7. Jasmonic acid distribution and action in plants: regulation during development and response to biotic and abiotic stress.

    Science.gov (United States)

    Creelman, R A; Mullet, J E

    1995-05-09

    Jasmonic acid (JA) is a naturally occurring growth regulator found in higher plants. Several physiological roles have been described for this compound (or a related compound, methyl jasmonate) during plant development and in response to biotic and abiotic stress. To accurately determine JA levels in plant tissue, we have synthesized JA containing 13C for use as an internal standard with an isotopic composition of [225]:[224] 0.98:0.02 compared with [225]:[224] 0.15:0.85 for natural material. GC analysis (flame ionization detection and MS) indicate that the internal standard is composed of 92% 2-(+/-)-[13C]JA and 8% 2-(+/-)-7-iso-[13C]JA. In soybean plants, JA levels were highest in young leaves, flowers, and fruit (highest in the pericarp). In soybean seeds and seedlings, JA levels were highest in the youngest organs including the hypocotyl hook, plumule, and 12-h axis. In soybean leaves that had been dehydrated to cause a 15% decrease in fresh weight, JA levels increased approximately 5-fold within 2 h and declined to approximately control levels by 4 h. In contrast, a lag time of 1-2 h occurred before abscisic acid accumulation reached a maximum. These results will be discussed in the context of multiple pathways for JA biosynthesis and the role of JA in plant development and responses to environmental signals.

  8. Molecular Cloning and Characterization of Three Novel Genes Related to Fatty Acid Degradation and Their Responses to Abiotic Stresses in Gossypium hirsutum L.

    Institute of Scientific and Technical Information of China (English)

    DONG Jia; WEI Li-bin; HU Yan; GUO Wang-zhen

    2013-01-01

    Fatty acid metabolism is responsible not only for oilseed metabolism but also for plant responses to abiotic stresses. In this study, three novel genes related to fatty acid degradation designated GhACX, Gh4CL, and GhMFP, respectively, were isolated from Gossypium hirsutum acc. TM-1. The phylogenetic analysis revealed that amino acid sequences of GhACX and GhMFP have the highest homology with those from Vitis vinifera, and Gh4CL has a closer genetic relationship with that from Camellia sinensis. Tissue-and organ-specific analysis showed that the three genes expressed widely in all the tested tissues, including ovules and fiber at different developing stages, with expressed preferentially in some organs. Among them, GhACX showed the most abundant transcripts in seeds at 25 d post anthesis (DPA), however, GhMFP and Gh4CL have the strongest expression level in ovules on the day of anthesis. Based on real-time quantitative RT-PCR, the three genes were differentially regulated when induced under wounding, methyl jasmonate (MeJA), cold, and abscisic acid (ABA) treatments. The characterization and expression pattern of three novel fatty acid degradation related genes will aid both to understand the roles of fatty acid degradation related genes as precursor in stress stimuli and to elucidate the physiological function in cotton oilseed metabolism.

  9. Transcriptional profiling of the PDR gene family in rice roots in response to plant growth regulators, redox perturbations and weak organic acid stresses.

    Science.gov (United States)

    Moons, Ann

    2008-12-01

    The role of plant pleiotropic drug resistance (PDR) type ATP-binding cassette (ABC) transporters remains poorly understood. We characterized the expression of the rice pleiotropic drug resistance (PDR) gene family in roots, where PDR transporters are believed to have major functions. A prototypical oligonucleotide array was developed containing 70-mers chosen in the gene-specific 3' untranslated regions of the rice PDR genes, other full-molecule rice ABC transporter genes and relevant marker genes. Jasmonates, which are involved in plant defense and secondary metabolism, proved major inducers of PDR gene expression. Over half of the PDR genes were JA-induced in roots of rice; OsPDR9 to the highest level. Salicylic acid, involved in plant pathogen defense, markedly induced the expression of OsPDR20. OsPDR20 was cDNA cloned and characterized. Abscisic acid, typically involved in water deficit responses, particularly induced OsPDR3 in roots and shoot and OsPDR6 in rice leaves. OsPDR9 and OsPDR20 were furthermore up-regulated in response to dithiothreitol- or glutathione-induced redox perturbations. Exogenous application of the weak organic acids lactic acid, malic acid, and citric acid differentially induced the expression of OsPDR3, OsPDR8, OsPDR9 and OsPDR20 in rice seedling roots. This transcriptional survey represents a guide for the further functional analysis of individual PDR transporters in roots of rice.

  10. Influence of fatty acids on pressor responses to catecholamines.

    Science.gov (United States)

    Chopde, C T; Brahmankar, D M; Jadhav, S S; Hardas, A P; Dorle, A K

    1975-01-01

    Lauric, Myristic and Palmitic acids had no appreciable effect whereas Stearic, Oleic and Linoleic acids caused some reduction in dog blood pressure. Pressor responses to epinephrine and nor-epinephrine were potentiated whereas the depressor response to isoproterenol was reduced during the infusion of fatty acids in dogs. ACTH alone, which causes mobilization of free fatty acids had no appreciable effect on blood pressure responses to catecholamines, however, its administration followed by salicylate produced marked potentiation of the pressor responses to epinephrine and nor-epinephrine; the depressor response to isoproterenol was reduced.

  11. Effects of Different Treatment Times of Abscisic Acid on the Accumulation of Active Constituents of Salvia miltiorrhiza Hairy Root%脱落酸不同处理时间对丹参毛状根有效成分积累的影响

    Institute of Scientific and Technical Information of China (English)

    盛东峰; 朱自学

    2013-01-01

    The objective of this study was to investigate the effects of abscisic acid (ABA) treatment times on the accumulation of active constituents of Salvia miltiorrhiza hairy root.The contents of tanshinones (including tanshinone I,cryptotanshinone,dihydrotanshinon Ⅰ and Ⅱ A) in S.miltiorrhiza hairy root was quantified after 0,1,3,6,9 days' treatment of ABA by HPLC.The results showed that:1) the growth of S.miltiorrhiza hairy roots was inhibited with the ABA treatment.The inhibition effect was decreased with the increasing of treatment time and became stable at day 6 ;2) The yields and the contents of four tanshinone components of S.miltiorrhiza hairy roots were also stable at day 6.the yields of tanshinone I,cryptotanshinone,dihydrotanshinon Ⅰ and Ⅱ A were 4.65,7.80,18.33 and 2.11 times of the control group after dealing with ABA;3)The root growth and the tanshinone production were inhibited efficiently by FOS and MEV and TUN.%采用HPLC测定脱落酸(abscisic acid,ABA)处理1、3、6、9d后丹参毛状根中丹参酮Ⅰ、隐丹参酮、二氢丹参酮Ⅰ、丹参酮ⅡA含量的方法,研究不同ABA处理时间对丹参酮类成分积累的影响.结果表明:①随着ABA处理时间的增加,丹参毛状根生长受到抑制逐渐减弱,并在处理6d左右变的不显著;②毛状根中四种丹参酮的产量和含量均在ABA处理6d左右趋于稳定.其中丹参酮Ⅰ、隐丹参酮、二氢丹参酮Ⅰ和丹参酮Ⅱ的产量分别提高为空白对照组的4.65、7.80、18.33和2.11倍;③三种丹参酮类合成抑制剂均对丹参毛状根的生长、丹参酮类的合成有抑制作用.

  12. Folinic acid-responsive seizures initially responsive to pyridoxine.

    NARCIS (Netherlands)

    Nicolai, J.; Kranen-Mastenbroek, V.H. van; Wevers, R.A.; Hurkx, W.A.; Vles, J.S.

    2006-01-01

    This report presents a male who developed clonic seizures on the day he was born. The next day, the diagnosis of pyridoxine-dependent seizures was made. However, contradictory to this diagnosis, seizures reappeared despite treatment with pyridoxine. Seizures ceased after folinic acid was initiated.

  13. Analysis of proteins responsive to acetic acid in Acetobacter: molecular mechanisms conferring acetic acid resistance in acetic acid bacteria.

    Science.gov (United States)

    Nakano, Shigeru; Fukaya, Masahiro

    2008-06-30

    Acetic acid bacteria are used for industrial vinegar production because of their remarkable ability to oxidize ethanol and high resistance to acetic acid. Although several molecular machineries responsible for acetic acid resistance in acetic acid bacteria have been reported, the entire mechanism that confers acetic acid resistance has not been completely understood. One of the promising methods to elucidate the entire mechanism is global analysis of proteins responsive to acetic acid by two-dimensional gel electrophoresis. Recently, two proteins whose production was greatly enhanced by acetic acid in Acetobacter aceti were identified to be aconitase and a putative ABC-transporter, respectively; furthermore, overexpression or disruption of the genes encoding these proteins affected acetic acid resistance in A. aceti, indicating that these proteins are involved in acetic acid resistance. Overexpression of each gene increased acetic acid resistance in Acetobacter, which resulted in an improvement in the productivity of acetic acid fermentation. Taken together, the results of the proteomic analysis and those of previous studies indicate that acetic acid resistance in acetic acid bacteria is conferred by several mechanisms. These findings also provide a clue to breed a strain having high resistance to acetic acid for vinegar fermentation.

  14. Low Phytic Acid Barley Responses to Phosphorus Rates

    Science.gov (United States)

    Low phytic acid (LPA) barley (Hordeum vulgare L.) cultivars partition phosphorus in seed tissue differently than conventional barley cultivars through a reduction in seed phytic acid (myo-inositol-1,2,3,4,5,6-hexkisphosphate) coupled with an increase in inorganic phosphorus. The response of the LPA...

  15. Perfluorooctanoic Acid Exposure Suppresses T-independent Antibody Responses

    Science.gov (United States)

    Exposure to  3.75mg/kg of perfluoroocatnoic acid (PFOA) for 15d suppresses T-dependent antibody responses (TDAR), suggesting that T helper cells and/or B cells/plasma cells may be impacted. This study evaluated effects of PFOA exposure on the T cell-independent antibody response...

  16. Hormonal and Hydroxycinnamic Acids Profiles in Banana Leaves in Response to Various Periods of Water Stress

    Directory of Open Access Journals (Sweden)

    Jalel Mahouachi

    2014-01-01

    Full Text Available The pattern of change in the endogenous levels of several plant hormones and hydroxycinnamic acids in addition to growth and photosynthetic performance was investigated in banana plants (Musa acuminata cv. “Grand Nain” subjected to various cycles of drought. Water stress was imposed by withholding irrigation for six periods with subsequent rehydration. Data showed an increase in abscisic acid (ABA and indole-3-acetic acid (IAA levels, a transient increase in salicylic acid (SA concentration, and no changes in jasmonic acid (JA after each period of drought. Moreover, the levels of ferulic (FA and cinnamic acids (CA were increased, and plant growth and leaf gas exchange parameters were decreased by drought conditions. Overall, data suggest an involvement of hormones and hydroxycinnamic acids in plant avoidance of tissue dehydration. The increase in IAA concentration might alleviate the senescence of survival leaves and maintained cell elongation, and the accumulation of FA and CA could play a key role as a mechanism of photoprotection through leaf folding, contributing to the effect of ABA on inducing stomatal closure. Data also suggest that the role of SA similarly to JA might be limited to a transient and rapid increase at the onset of the first period of stress.

  17. Role of Nitric Oxide in Abscisic Acid-induced Subcellular Antioxidant Defense of Maize Leaves%一氧化氮在脱落酸诱导的玉米叶片亚细胞抗氧化防护中的作用

    Institute of Scientific and Technical Information of China (English)

    桑建荣; 蒋明义; 林凡; 李晶; 许树成

    2007-01-01

    The sources of nitric oxide(NO)production in response to abscisic acid(ABA)and the role of NO in ABA-induced hydrogen peroxide(H2O2)accumulation and subcellular antioxidant defense in leaves of maize (Zea mays L.)plants were investigated.ABA induced increases in generation of NO and activity of nitric Oxide synthase (NOS) in maize leaves.Such increases were blocked by pretreatment with each of the two NOS inhibitors.Pretreatments with a NO scavenger or NR inhibitors inhibited ABA-induced increase in production of NO.but did not aflfect the ABA-induced increases in activity of NOS,indicating that ABA-induced NO production originated from sources of NOS and NR.ABAand H2O2-induced increases in expression of the antioxidant genes superoxide dismutase 4(SOD4),cytosolic ascorbate peroxidase(cAPS),and glutathione reductase 1(GR1)and the activities of the chloroplastic and cytosolic antioxidant enzymes were alTeSted by pretreatments with the NO scavenger.inhibitors of NOS and NR,indicaring that NO iS involved in the ABA-and H2O2-induced subcellular antioxidant defense reactions.On the other hand,NO donor sodium nitroprusside(SNP)reduced accumulation of H2O2 induced by ABA,and CPTIO reversed the effect of SNP in decreasing the accumulation of H2O2.SNP induced increases in activities of subcellular antioxidant enzymes,and the increases were substantially prevented from occurring by the pretreatment with c-PTIO.These results suggest that ABA in duces production of H2O2 and NO,which can up-regulate activities of the subcellular antioxidant enzymes,to prevent overproduction of H2O2 in maize plants.There is a negative feedback loop between NO and H2O2 in ABA signal transduction in maize plants.%研究了ABA诱导NO产生的来源以及NO在ABA诱导的玉米叶片H2O2累积和亚细胞水平抗氧化中的作用.ABA诱导玉米叶片NO的产生以及NOS 活性增加,NOS抑制剂抑制这种增加.NO清除剂和NR抑制剂预处理也抑制了ABA诱导的NO产生,但是并不影

  18. Metabolic Response of Pakchoi Leaves to Amino Acid Nitrogen

    Institute of Scientific and Technical Information of China (English)

    WANG Xiao-li; YU Wen-juan; ZHOU Qian; HAN Rui-feng; HUANG Dan-feng

    2014-01-01

    Different nitrogen (N) forms may cause changes in the metabolic profiles of plants. However, few studies have been conducted on the effects of amino acid-N on plant metabolic proifles. The main objective of this study was to identify primary metabolites associated with amino acid-N (Gly, Gln and Ala) through metabolic proifle analysis using gas chromatography-mass spectrometry (GC-MS). Plants of pakchoi (Brassica campestris L. ssp. chinensis L.), Huawang and Wuyueman cultivars, were grown with different nitrogen forms (i.e., Gly, Gln, Ala, NO3--N, and N starvation) applied under sterile hydroponic conditions. The fresh weight and plant N accumulation of Huawang were greater than those of Wuyueman, which indicates that the former exhibited better N-use efficiency than the latter. The physiological performances of the applied N forms were generally in the order of NO3--N>Gln>Gly>Ala. The metabolic analysis of leaf polar extracts revealed 30 amino acid N-responsive metabolites in the two pakchoi cultivars, mainly consisting of sugars, amino acids, and organic acids. Changes in the carbon metabolism of pakchoi leaves under amino acid treatments occurred via the accumulation of fructose, glucose, xylose, and arabinose. Disruption of amino acid metabolism resulted in accumulation of endogenous Gly in Gly treatment, Pro in Ala treatment, and Asn in three amino acid (Gly, Gln and Ala) treatments. By contrast, the levels of endogenous Gln and Leu decreased. However, this reduction varied among cultivars and amino acid types. Amino acid-N supply also affected the citric acid cycle, namely, the second stage of respiration, where leaves in Gly, Gln and Ala treatments contained low levels of malic, citric and succinic acids compared with leaves in NO3--N treatments. No signiifcant difference in the metabolic responses was observed between the two cultivars which differed in their capability to use N. The response of primary metabolites in pakchoi leaves to amino acid-N supply

  19. Acid tolerance response (ATR) of microbial communities during the enhanced biohydrogen process via cascade acid stress.

    Science.gov (United States)

    Lin, Xiaoqin; Xia, Yan; Yan, Qun; Shen, Wei; Zhao, Mingxing

    2014-03-01

    Enhanced biohydrogen production via cascade acid stress on microbial communities, structure patterns of the microbial communities revealed by PLFAs, and the succession of biohydrogen related species against cascade acid stress were all investigated. It was found that hydrogen production could be improved from 48.7 to 79.4mL/gVS after cascade acid stress. In addition, the Gram negative (G(-)) bacteria were found to be more tolerant to organic acids than those of the Gram positive (G(+)) bacteria, regardless of the dominance of G(+) bacteria within the microbial communities. Moreover, Clostridium butyricum, Clostridium aciditolerans and Azospira oryzae, were proved to be enriched, and then might play indispensable roles for the enhanced biohydrogen production after cascade acid stress, as which were responsible for the biohydrogen accumulation, acid tolerance and nitrogen removal, respectively.

  20. Pear 14-3-3a gene (Pp14-3-3a) is regulated during fruit ripening and senescense, and involved in response to salicylic acid and ethylene signalling

    Indian Academy of Sciences (India)

    Haiyan Shi; Yuxing Zhang

    2014-12-01

    14-3-3 proteins play important roles in regulating plant development and phytohormone (abscisic acid, gibberellin and brassinosteroids) signalling. However, their regulation in fruit ripening and senescense, and response to salicylic acid and ethylene signalling are yet to be illustrated. One cDNA encoding putative 14-3-3 protein was isolated from pear (Pyrus pyrifolia) and designated Pp14-3-3a. Phylogenetic analysis clearly demonstrated that Pp14-3-3a belonged to -like group of 14-3-3 super-families. Real-time quantitative PCR analysis indicated that the expression of Pp14-3-3a gene was developmentally regulated in the fruit. Further study demonstrated that Pp14-3-3a expression was inhibited by salicylic acid and induced by ethylene precursor 1-aminocyclopropane-1-carboxylic acid in pear fruit. These data suggested that Pp14-3-3a might be involved in response to salicylic acid and ethylene signalling during fruit ripening and senescence of pear.

  1. 外源ABA缓解黄瓜幼苗中低温诱导的氧化损伤%Exogenous abscisic acid alleviates low temperature-induced oxidative damage in seedlings of Cucumis sativus.L

    Institute of Scientific and Technical Information of China (English)

    张颖; 蒋卫杰; 余宏军; 杨学勇

    2012-01-01

    脱落酸作为胁迫激素可提高植物对胁迫的抵抗能力,但亚适温下合理应用脱落酸提高植物抗性的研究较少.该文研究了脱落酸(ABA)预处理对亚低温环境下津研4号(低温敏感型品种)和中农27号(耐低温品种)的影响.于黄瓜三叶期分别喷施200 μmol/L ABA或清水,预处理12 h后分为2组,放入温度分别为25/18℃(昼/夜)和10/10℃(昼/夜)2个人工气候室培养7d.测定电导率、组织含水量、叶绿素含量,抗氧化酶活性以及相关酶的基因表达变化.结果表明,低温处理后,2黄瓜品种幼苗的电导率增加,组织含水量和叶绿素含量下降,过氧化物酶(POD)和超氧化物歧化酶(SOD)的活性增加,而过氧化氢酶(CAT)活性降低.与清水对照相比,ABA预处理有效的缓解了上述生理指标在低温下的变化.此外,低温处理后CAT基因表达量下调,SOD基因的表达量上调,而喷施ABA同样缓解了低温下CAT的下调表达和SOD的上调表达.说明ABA通过平衡活性氧的产生和清除来减轻低温对黄瓜幼苗的伤害,为外源ABA应用于植物抗低温生产提供理论依据.%Absicsic acid (ABA) as a kind of stress hormone has been applied to enhance a plant's resistance to various abiotic stresses,but the effect of ABA on sub-optimal temperature stress has not been clarified.The effects of ABA pretreatment on two cultivars of cucumber seedlings (chilling sensitive Jinyan 4 and chilling tolerant Zhongnong 27)under chilling stress were investigated.The cucumber seedlings were pretreated with 200 μmol/L ABA or water for 12 h,then divided into two groups and cultivated separately in two phytotrons with temperatures 25/18℃ and 10/10℃(day/night) for seven days,respectively.The level of electrolyte leakage,the tissue water content (TWC),the chlorophyll content,the antioxidant enzyme activities and the transcriptional levels of the genes encoding these enzymes were measured.The results showed that the level of

  2. Acid stress response and protein induction in Campylobacter jejuni isolates with different acid tolerance

    Directory of Open Access Journals (Sweden)

    Birk Tina

    2012-08-01

    Full Text Available Abstract Background During the transmission route from poultry to the human host, the major foodborne pathogen C. jejuni may experience many types of stresses, including low pH caused by different acids. However, not all strains are equally sensitive to the stresses. The aim of this study was to investigate the response to acid stress of three sequenced C. jejuni strains with different acid tolerances using HCl and acetic acid. Results Two-dimensional gel electrophoresis was used for proteomic analysis and proteins were radioactively labelled with methionine to identify proteins only related to acid exposure. To allow added radioactive methionine to be incorporated into induced proteins, a modified chemically defined broth was developed with the minimal amount of methionine necessary for satisfactory growth of all strains. Protein spots were analyzed using image software and identification was done with MALDI-TOF-TOF. The most acid-sensitive isolate was C. jejuni 327, followed by NCTC 11168 and isolate 305 as the most tolerant. Overall, induction of five proteins was observed within the pI range investigated: 19 kDa periplasmic protein (p19, thioredoxin-disulfide (TrxB, a hypothetical protein Cj0706 (Cj0706, molybdenum cofactor biosynthesis protein (MogA, and bacterioferritin (Dps. Strain and acid type dependent differences in the level of response were observed. For strain NCTC 11168, the induced proteins and the regulator fur were analysed at the transcriptomic level using qRT-PCR. In this transcriptomic analysis, only up-regulation of trxB and p19 was observed. Conclusions A defined medium that supports the growth of a range of Campylobacter strains and suitable for proteomic analysis was developed. Mainly proteins normally involved in iron control and oxidative stress defence were induced during acid stress of C. jejuni. Both strain and acid type affected sensitivity and response.

  3. Control of immune response by amino acid metabolism.

    Science.gov (United States)

    Grohmann, Ursula; Bronte, Vincenzo

    2010-07-01

    The interaction between pathogenic microorganisms and their hosts is regulated by reciprocal survival strategies, including competition for essential nutrients. Though paradoxical, mammalian hosts have learned to take advantage of amino acid catabolism for controlling pathogen invasion and, at the same time, regulating their own immune responses. In this way, ancient catabolic enzymes have acquired novel functions and evolved into new structures with highly specialized functions, which go beyond the struggle for survival. In this review, we analyze the evidence supporting a critical role for the metabolism of various amino acids in regulating different steps of both innate and adaptive immunity.

  4. WRKY Transcription Factors: Key Components in Abscisic Acid Signaling

    Science.gov (United States)

    2011-01-01

    2008). In cereals, upon imbibing, the embryos of nondormant seeds produce GA. This GA is transported to the aleurone, a thin layer of cells surround- ing...sensing, signaling and transport . Plant Cell Physiol. 51, 1821–1839. Urano, K., Kurihara, Y., Seki, M. and Shinozaki, K. (2010) ‘Omics’ analyses of...galactinol synthase (BhGolS1) promoter. Planta , 230, 1155–1166. Wu, F.-Q., Xin, Q., Cao, Z., Liu, Z.-Q., Du, S.-Y., Mei, C., Zhao, C.-X., Wang, X.-F

  5. Hemicrania continua evolving from cluster headache responsive to valproic acid.

    Science.gov (United States)

    Lambru, Giorgio; Castellini, Paola; Bini, Annamaria; Evangelista, Andrea; Manzoni, Gian Camillo; Torelli, Paola

    2008-10-01

    Hemicrania continua (HC) is a rare type of primary headache characterized by a prompt and enduring response to indomethacin. We describe a patient who suffered from cluster headache evolving into ipsilateral HC, who does not tolerate a long-term indomethacin therapy. The case was complex in terms of diagnosis, associated comorbidity, and choice of treatment; after several trials with different therapeutic regimens, we started the patient on a therapy with valproic acid and obtained an improvement of her HC.

  6. Lactic acid delays the inflammatory response of human monocytes

    Energy Technology Data Exchange (ETDEWEB)

    Peter, Katrin, E-mail: katrin.peter@ukr.de [Department of Internal Medicine III, University Hospital Regensburg, Franz-Josef-Strauß-Allee 11, 93053 Regensburg (Germany); Rehli, Michael, E-mail: michael.rehli@ukr.de [Department of Internal Medicine III, University Hospital Regensburg, Franz-Josef-Strauß-Allee 11, 93053 Regensburg (Germany); RCI Regensburg Center for Interventional Immunology, University Hospital Regensburg, Franz-Josef-Strauß-Allee 11, 93053 Regensburg (Germany); Singer, Katrin, E-mail: katrin.singer@ukr.de [Department of Internal Medicine III, University Hospital Regensburg, Franz-Josef-Strauß-Allee 11, 93053 Regensburg (Germany); Renner-Sattler, Kathrin, E-mail: kathrin.renner-sattler@ukr.de [Department of Internal Medicine III, University Hospital Regensburg, Franz-Josef-Strauß-Allee 11, 93053 Regensburg (Germany); Kreutz, Marina, E-mail: marina.kreutz@ukr.de [Department of Internal Medicine III, University Hospital Regensburg, Franz-Josef-Strauß-Allee 11, 93053 Regensburg (Germany); RCI Regensburg Center for Interventional Immunology, University Hospital Regensburg, Franz-Josef-Strauß-Allee 11, 93053 Regensburg (Germany)

    2015-02-13

    Lactic acid (LA) accumulates under inflammatory conditions, e.g. in wounds or tumors, and influences local immune cell functions. We previously noted inhibitory effects of LA on glycolysis and TNF secretion of human LPS-stimulated monocytes. Here, we globally analyze the influence of LA on gene expression during monocyte activation. To separate LA-specific from lactate- or pH-effects, monocytes were treated for one or four hours with LPS in the presence of physiological concentrations of LA, sodium lactate (NaL) or acidic pH. Analyses of global gene expression profiles revealed striking effects of LA during the early stimulation phase. Up-regulation of most LPS-induced genes was significantly delayed in the presence of LA, while this inhibitory effect was attenuated in acidified samples and not detected after incubation with NaL. LA targets included genes encoding for important monocyte effector proteins like cytokines (e.g. TNF and IL-23) or chemokines (e.g. CCL2 and CCL7). LA effects were validated for several targets by quantitative RT-PCR and/or ELISA. Further analysis of LPS-signaling pathways revealed that LA delayed the phosphorylation of protein kinase B (AKT) as well as the degradation of IκBα. Consistently, the LPS-induced nuclear accumulation of NFκB was also diminished in response to LA. These results indicate that the broad effect of LA on gene expression and function of human monocytes is at least partially caused by its interference with immediate signal transduction events after activation. This mechanism might contribute to monocyte suppression in the tumor environment. - Highlights: • Lactic acid broadly delays LPS-induced gene expression in human monocytes. • Expression of important monocyte effector molecules is affected by lactic acid. • Interference of lactic acid with TLR signaling causes the delayed gene expression. • The profound effect of lactic acid might contribute to immune suppression in tumors.

  7. Molecular Cloning and Characterization of a Novel Gene Involved in Fatty Acid Synthesis in Brassica napus L.

    Institute of Scientific and Technical Information of China (English)

    XIAO Gang; ZHANG Zhen-qian; LIU Rui-yang; YIN Chang-fa; WU Xian-meng; TAN Tai-long; GUAN Chun-yun

    2013-01-01

    Based on the sequence of a novel expressed sequence tag (EST), the full-length cDNA of 1 017 nucleotides was cloned from Brassica napus cv. Xiangyou 15 through rapid amplification of cDNA ends (RACE). The gene was designated as Bnhol34 (HQ585980), encoding a protein of 338 amino acids. BLAST analysis showed no high degree of sequence identity to any known gene. The calculated molecular weight of the Bnhol34 protein was 36.23 kDa, and the theoretical isoelectric point was 8.74. The Bnhol34 was also cloned from a high oleic acid mutant 854-1 through homologous cloning. There was no difference between the two Bnhol34 genes. Bnhol34 was localized in a tissue-specific manner in B. napus, and its expression level was about eight-fold greater in Xiangyou 15 seeds than in 854-1. The promoter region sequences of Bnhol34 were then isolated from Xiangyou 15 and 854-1, and a 93-bp deletion was found to occur in the Bnhol34 promoter region of 854-1. Three abscisic acid-responsive cis-elements (ABRE) were identified in the promoter region of Xiangyou 15. Real-time PCR analyses revealed that exogenous abscisic acid increased Bnhol34 expression by about four-fold in Xiangyou 15 seeds, yet did not change Bnhol34 expression in 854-1. It appeared that Bnhol34 might be abscisic acid insensitive in 854-1.

  8. Role of Protein Kinases in Abscisic Acid and H2O2 Induced Antioxidant Defense in Maize%蛋白激酶组在玉米叶片ABA和H2O2诱导抗氧化防护中的作用

    Institute of Scientific and Technical Information of China (English)

    许树成; 祝雪兰; 张丽

    2011-01-01

    Protein phosphorylation plays a central role in mediating abscisic acid (ABA) signaling transduction in plant cells, whereas many of the sensory proteins involving in ABA signaling pathway remain unclear. Here, using a modified in vitro kinase assay, our results showed that ABA and H2O2 induced a rapid activation of total protein ki-nases and calcium dependent protein kinases in the leaves of maize seedlings. However, ABA-induced activation of protein kinases was inhibited by reactive oxygen species (ROS) inhibitors or scavengers. Protein kinase inhibitors decelerated not only the ABA and H2O2-induced kinase activity but also ABA or H2O2 -induced antioxidant enzyme activity. Protein phosphorylation caused by ABA and H2O2 preceded ABA or H2O2-induced antioxidant defense obviously. Using in-gel kinase assays, our results showed that several protein kinases with molecular masses of 66 kDa, 52 kDa, 49 kDa and 35 kDa respectively might mediate ABA and H2O2-induced antioxidant defense. And the 66 kDa and 49 kDa protein kinases may act downstream of ROS, and the 52 kDa and 35 kDa protein kinases may act between ABA and ROS in ABA-induced antioxidant defensive signaling.%蛋白磷酸化在植物细胞脱落酸(ABA)介导的信号转导中起重要作用.然而,很多参与ABA信号途径的蛋白元件仍不清楚.使用改进的体外激酶试验方法的研究结果表明,在玉米叶片中,ABA和H2O2能够快速活化蛋白激酶总活性和Ca2+依赖型蛋白激酶总活性;ABA诱导的蛋白激酶总活性增加可以被活性氧的抑制剂和清除剂抑制,蛋白激酶抑制剂不仅可以降低ABA和H2O2诱导的激酶活性增加,而且也可以弱化它们对抗氧化防护酶活性的诱导作用;ABA和H2O2引发的蛋白磷酸化作用显著居先于它们诱导的抗氧化防护作用.使用凝胶激酶试验方法进行研究发现,一组分子量分别为66 kDa,52 kDa,49 kDa和35kDa的蛋白激酶可能介导了ABA和H2O2诱导

  9. Acid and base stress and transcriptomic responses in Bacillus subtilis.

    Science.gov (United States)

    Wilks, Jessica C; Kitko, Ryan D; Cleeton, Sarah H; Lee, Grace E; Ugwu, Chinagozi S; Jones, Brian D; BonDurant, Sandra S; Slonczewski, Joan L

    2009-02-01

    Acid and base environmental stress responses were investigated in Bacillus subtilis. B. subtilis AG174 cultures in buffered potassium-modified Luria broth were switched from pH 8.5 to pH 6.0 and recovered growth rapidly, whereas cultures switched from pH 6.0 to pH 8.5 showed a long lag time. Log-phase cultures at pH 6.0 survived 60 to 100% at pH 4.5, whereas cells grown at pH 7.0 survived acid or base induced adaptation to a more extreme acid or base, respectively. Expression indices from Affymetrix chip hybridization were obtained for 4,095 protein-encoding open reading frames of B. subtilis grown at external pH 6, pH 7, and pH 9. Growth at pH 6 upregulated acetoin production (alsDS), dehydrogenases (adhA, ald, fdhD, and gabD), and decarboxylases (psd and speA). Acid upregulated malate metabolism (maeN), metal export (czcDO and cadA), oxidative stress (catalase katA; OYE family namA), and the SigX extracytoplasmic stress regulon. Growth at pH 9 upregulated arginine catabolism (roc), which generates organic acids, glutamate synthase (gltAB), polyamine acetylation and transport (blt), the K(+)/H(+) antiporter (yhaTU), and cytochrome oxidoreductases (cyd, ctaACE, and qcrC). The SigH, SigL, and SigW regulons were upregulated at high pH. Overall, greater genetic adaptation was seen at pH 9 than at pH 6, which may explain the lag time required for growth shift to high pH. Low external pH favored dehydrogenases and decarboxylases that may consume acids and generate basic amines, whereas high external pH favored catabolism-generating acids.

  10. Acidic chitinase primes the protective immune response to gastrointestinal nematodes.

    Science.gov (United States)

    Vannella, Kevin M; Ramalingam, Thirumalai R; Hart, Kevin M; de Queiroz Prado, Rafael; Sciurba, Joshua; Barron, Luke; Borthwick, Lee A; Smith, Allen D; Mentink-Kane, Margaret; White, Sandra; Thompson, Robert W; Cheever, Allen W; Bock, Kevin; Moore, Ian; Fitz, Lori J; Urban, Joseph F; Wynn, Thomas A

    2016-05-01

    Acidic mammalian chitinase (AMCase) is known to be induced by allergens and helminths, yet its role in immunity is unclear. Using AMCase-deficient mice, we show that AMCase deficiency reduced the number of group 2 innate lymphoid cells during allergen challenge but was not required for establishment of type 2 inflammation in the lung in response to allergens or helminths. In contrast, AMCase-deficient mice showed a profound defect in type 2 immunity following infection with the chitin-containing gastrointestinal nematodes Nippostrongylus brasiliensis and Heligmosomoides polygyrus bakeri. The impaired immunity was associated with reduced mucus production and decreased intestinal expression of the signature type 2 response genes Il13, Chil3, Retnlb, and Clca1. CD103(+) dendritic cells, which regulate T cell homing, were also reduced in mesenteric lymph nodes of infected AMCase-deficient mice. Thus, AMCase functions as a critical initiator of protective type 2 responses to intestinal nematodes but is largely dispensable for allergic responses in the lung.

  11. Complex modulation of androgen responsive gene expression by methoxyacetic acid

    Directory of Open Access Journals (Sweden)

    Stanley Kerri A

    2011-03-01

    Full Text Available Abstract Background Optimal androgen signaling is critical for testicular development and spermatogenesis. Methoxyacetic acid (MAA, the primary active metabolite of the industrial chemical ethylene glycol monomethyl ether, disrupts spermatogenesis and causes testicular atrophy. Transcriptional trans-activation studies have indicated that MAA can enhance androgen receptor activity, however, whether MAA actually impacts the expression of androgen-responsive genes in vivo, and which genes might be affected is not known. Methods A mouse TM3 Leydig cell line that stably expresses androgen receptor (TM3-AR was prepared and analyzed by transcriptional profiling to identify target gene interactions between MAA and testosterone on a global scale. Results MAA is shown to have widespread effects on androgen-responsive genes, affecting processes ranging from apoptosis to ion transport, cell adhesion, phosphorylation and transcription, with MAA able to enhance, as well as antagonize, androgenic responses. Moreover, testosterone is shown to exert both positive and negative effects on MAA gene responses. Motif analysis indicated that binding sites for FOX, HOX, LEF/TCF, STAT5 and MEF2 family transcription factors are among the most highly enriched in genes regulated by testosterone and MAA. Notably, 65 FOXO targets were repressed by testosterone or showed repression enhanced by MAA with testosterone; these include 16 genes associated with developmental processes, six of which are Hox genes. Conclusions These findings highlight the complex interactions between testosterone and MAA, and provide insight into the effects of MAA exposure on androgen-dependent processes in a Leydig cell model.

  12. Transcriptome analysis of H2O2-treated wheat seedlings reveals a H2O2-responsive fatty acid desaturase gene participating in powdery mildew resistance.

    Directory of Open Access Journals (Sweden)

    Aili Li

    Full Text Available Hydrogen peroxide (H(2O(2 plays important roles in plant biotic and abiotic stress responses. However, the effect of H(2O(2 stress on the bread wheat transcriptome is still lacking. To investigate the cellular and metabolic responses triggered by H(2O(2, we performed an mRNA tag analysis of wheat seedlings under 10 mM H(2O(2 treatment for 6 hour in one powdery mildew (PM resistant (PmA and two susceptible (Cha and Han lines. In total, 6,156, 6,875 and 3,276 transcripts were found to be differentially expressed in PmA, Han and Cha respectively. Among them, 260 genes exhibited consistent expression patterns in all three wheat lines and may represent a subset of basal H(2O(2 responsive genes that were associated with cell defense, signal transduction, photosynthesis, carbohydrate metabolism, lipid metabolism, redox homeostasis, and transport. Among genes specific to PmA, 'transport' activity was significantly enriched in Gene Ontology analysis. MapMan classification showed that, while both up- and down- regulations were observed for auxin, abscisic acid, and brassinolides signaling genes, the jasmonic acid and ethylene signaling pathway genes were all up-regulated, suggesting H(2O(2-enhanced JA/Et functions in PmA. To further study whether any of these genes were involved in wheat PM response, 19 H(2O(2-responsive putative defense related genes were assayed in wheat seedlings infected with Blumeria graminis f. sp. tritici (Bgt. Eight of these genes were found to be co-regulated by H(2O(2 and Bgt, among which a fatty acid desaturase gene TaFAD was then confirmed by virus induced gene silencing (VIGS to be required for the PM resistance. Together, our data presents the first global picture of the wheat transcriptome under H(2O(2 stress and uncovers potential links between H(2O(2 and Bgt responses, hence providing important candidate genes for the PM resistance in wheat.

  13. Expected genetic response for oleic acid content in pork.

    Science.gov (United States)

    Ros-Freixedes, R; Reixach, J; Tor, M; Estany, J

    2012-12-01

    Intramuscular fat (IMF) and oleic acid (C18:1) content in pork are important issues for the pig industry and consumers. Data from a purebred Duroc line were used to i) estimate the genetic parameters of IMF and C18:1 and their genetic correlations with lean growth components, and ii) evaluate the opportunities for genetically improving C18:1 in IMF. The data set used for estimating genetic parameters consisted of 93,920 pigs, from which 85,194 had at least 1 record for BW or backfat thickness (BT) at 180 d and 943 for IMF and C18:1 at 205 d. Intramuscular fat content and C18:1, expressed as percentage of total fatty acids, were determined in the gluteus medius muscle by gas chromatography. Genetic parameters for C18:1 were estimated under a Bayesian 4-trait multivariate animal mixed model. Heritability of C18:1 was 0.50, with a probability of 95% of being greater than 0.37. Genetic correlations of C18:1 with BW, BT, and IMF were 0.11, 0.22, and 0.47, respectively (with a probability of 95% of being greater than -0.07, 0.04, and 0.27, respectively). Genetic responses were evaluated by deterministic simulation using a half-sib recording scheme for C18:1 and the previously estimated parameters. The C18:1 content is expected to exhibit only minor changes in selection programs directed at growth rate but to decrease in those focusing on lean content. Maximum expected response in C18:1 at no lean growth loss (i.e., at no change in BW and BT) was 0.44%, with a resulting correlated response in IMF of 0.15%. However, because lean growth is emphasized in the breeding goal, the resulting response scenarios are more constrained. We concluded that there is evidence to support the idea that C18:1 in IMF is genetically determined and defined selection strategies can lead to response scenarios in which C18:1, IMF, BT, and BW can be simultaneously improved. However, if adopted, the potential for lean growth would be reduced. The extent to which it is affordable relies on how much

  14. Acid stress response and protein induction in Campylobacter jejuni isolates with different acid tolerance

    DEFF Research Database (Denmark)

    Birk, Tina; Wik, Monica Takamiya; Lametsch, René

    2012-01-01

    BACKGROUND: During the transmission route from poultry to the human host, the major foodborne pathogen C. jejuni may experience many types of stresses, including low pH caused by different acids. However, not all strains are equally sensitive to the stresses. The aim of this study was to investig...... (Cj0706), molybdenum cofactor biosynthesis protein (MogA), and bacterioferritin (Dps). Strain and acid type dependent differences in the level of response were observed. For strain NCTC 11168, the induced proteins and the regulator fur were analysed at the transcriptomic level using q......RT-PCR. In this transcriptomic analysis, only up-regulation of trxB and p19 was observed. CONCLUSIONS: A defined medium that supports the growth of a range of Campylobacter strains and suitable for proteomic analysis was developed. Mainly proteins normally involved in iron control and oxidative stress defence were induced...

  15. 苹果果实细胞质中依赖活体组织的ABA高亲和力特异结合蛋白%In Vivo Tissue-dependent Abscisic Acid Specific-binding Proteins with High Affinity in Cytosol of Developing Apple Fruits

    Institute of Scientific and Technical Information of China (English)

    张大鹏; 陈尚武

    2001-01-01

    The in vivo highly tissue-dependent abscisic acid (ABA) specific-binding sit es localized in cytosol were identified and characterized in the flesh of develo ping apple (Malus pumila L. cv. Starkrimon) fruits. ABA binding activity was scarcely detectable in the microsomes and the cytosolic fraction isolated from the freshly harvested fruits via an in vitro ABA binding incubation of the s ubcellular fractions. If, however, instead that the subcellular fractions were in vitro incubated in 3H-ABA binding medium, the flesh tissue discs we re directly in vivo incubated in 3H-ABA binding medium, a high ABA bin ding activity to the cytosolic fraction isolated from these tissue discs was detect ed. The in vivo ABA binding capacity of the cytosolic fraction was lost if the tissue discs had been pretreated with boiling water, indicating that the ABA bin ding needs a living state of tissue. The in vivo tissue-dependent binding si tes were shown to possess protein nature with both active serine residua and thiol-g roup of cysteine residua in their functional binding center. The ABA binding of the in vivo tissue-dependent ABA binding sites to the cytosolic fraction was shown to be saturable, reversible, and of high affinity. The scatchard plotting g ave evidence of two different classes of ABA binding proteins, one with a higher affinity (Kd=2.9 nmol/L) and the other with lower affinity (Kd=71.4 nmo l/L). Ph aseic acid, 2-trans-4-trans-ABA or cis-trans-(-)-ABA had substantia lly no affinity to the binding proteins, indicating their stereo-specificity to bind physiologically active ABA. The time course, pH- and temperature-dependence of the in vivo tissue-dependent binding proteins were determined. It is hyp othesized that the detected ABA-binding proteins may be putative ABA-receptors t hat mediate ABA signals during fruit development.%将苹果(Malus pumila L. cv. Starkrimon)果肉微粒体和细胞可溶组分在含有 3H-ABA的缓冲介质中分别温育,仅在细胞

  16. Saturated fatty acids trigger TLR4-mediated inflammatory response.

    Science.gov (United States)

    Rocha, D M; Caldas, A P; Oliveira, L L; Bressan, J; Hermsdorff, H H

    2016-01-01

    Toll-like receptors (TLR) mediate infection-induced inflammation and sterile inflammation by endogenous molecules. Among the TLR family, TLR4 is the best understood. However, while its downstream signaling pathways have been well defined, not all ligands of TLR4 are currently known. Current evidence suggests that saturated fatty acids (SFA) act as non-microbial TLR4 agonists, and trigger its inflammatory response. Thus, our present review provides a new perspective on the potential mechanism by which SFAs could modulate TLR4-induced inflammatory responses: (1) SFAs can be recognized by CD14-TLR4-MD2 complex and trigger inflammatory pathways, similar to lipopolysaccharide (LPS). (2) SFAs lead to modification of gut microbiota with an overproduction of LPS after a high-fat intake, enhancing this natural TLR4 ligand. (3) In addition, this metabolic endotoxemia leads to an oxidative stress thereby producing atherogenic lipids - oxLDL and oxidized phospholipids - which trigger CD36-TLR4-TLR6 inflammatory response. (4) Also, the high SFA consumption increases the lipemia and the mmLDL and oxLDL formation through oxidative modifications of LDL. The mmLDL, unlike oxLDL, is involved in activation of the CD14-TLR4-MD2 inflammatory pathway. Those molecules can induce TLR4 inflammatory response by MyD88-dependent and/or MyD88-independent pathways that, in turn, promotes the expression of proinflammatory transcript factors such as factor nuclear kappa B (NF-κB), which plays a crucial role in the induction of inflammatory mediators (cytokines, chemokines, or costimulatory molecules) implicated in the development and progression of many chronic diseases.

  17. Boronic acid shell-crosslinked dextran-b-PLA micelles for acid-responsive drug delivery.

    Science.gov (United States)

    Zhao, Ziwei; Yao, Xuemei; Zhang, Zhe; Chen, Li; He, Chaoliang; Chen, Xuesi

    2014-11-01

    Herein, 3-carboxy-5-nitrophenylboronic acid (CNPBA) shell-crosslinked micelles based on amphiphilic dextran-block-polylactide (Dex-b-PLA) are prepared and used for efficient intracellular drug deliveries. Due to the reversible pH-dependent binding with diols to form boronate esters, CNPBA modified Dex-b-PLA shows excellent pH-sensitivity. In neutral aqueous conditions, CNPBA-Dex-b-PLA forms shell-crosslinked micelles to enable DOX loading, while in acid conditions, the boronate esters hydrolyze and the micelles de-crosslink to release loaded DOX. In vitro release studies indicate that the release of the DOX cargo is minimized at physiological conditions, while there is a burst release in response to low pHs. The cell viability of CNPBA-Dex-b-PLA investigated by MTT assay was more than 90%, indicating that, as a drug delivery system, CNPBA-Dex-b-PLA has good cytocompatibility. These features suggest that the pH-responsive biodegradable CNPBA-Dex-b-PLA can efficiently load and deliver DOX into tumor cells and enhance the inhibition of cellular proliferation in vitro, providing a favorable platform as a drug delivery system for cancer therapy.

  18. Salicylic Acid and its Function in Plant Immunity

    Institute of Scientific and Technical Information of China (English)

    Chuanfu An; Zhonglin Mou

    2011-01-01

    The small phenolic compound salicylic acid (SA) plays an important regulatory role in multiple physiological processes including plant immune response. Significant progress has been made during the past two decades in understanding the SA-mediated defense signaling network.Characterization of a number of genes functioning in SA biosynthesis,conjugation, accumulation, signaling, and crosstalk with other hormones such as jasmonic acid, ethylene, abscisic acid, auxin, gibberellic acid,cytokinin, brassinosteroid, and peptide hormones has sketched the finely tuned immune response network. Full understanding of the mechanism of plant immunity will need to take advantage of fast developing genomics tools and bioinformatics techniques. However, elucidating genetic components involved in these pathways by conventional genetics, biochemistry, and molecular biology approaches will continue to be a major task of the community. High-throughput method for SA quantification holds the potential for isolating additional mutants related to SA-mediated defense signaling.

  19. Arabidopsis MAP kinase 4 regulates salicylic acid- and jasmonic acid/ethylene-dependent responses via EDS1 and PAD4

    DEFF Research Database (Denmark)

    Brodersen, Klaus Peter; Petersen, Morten; Nielsen, Henrik Bjørn

    2006-01-01

    Arabidopsis MPK4 has been implicated in plant defense regulation because mpk4 knockout plants exhibit constitutive activation of salicylic acid (SA)-dependent defenses, but fail to induce jasmonic acid (JA) defense marker genes in response to JA. We show here that mpk4 mutants are also defective...

  20. Insulin dose response analysis of free fatty acid kinetics.

    Science.gov (United States)

    Jensen, Michael D; Nielsen, Søren

    2007-01-01

    Insulin regulation of free fatty acid (FFA) release is an important aspect of metabolic function; however, FFA release is exquisitely sensitive to insulin, which complicates the design and analysis of dose response experiments. We measured FFA ([(3)H]palmitate) and glucose ([(3)H]glucose) kinetics in 7 nonobese men, 7 nonobese women, 7 obese men, and 7 obese women by using a two-step insulin clamp (0.25 and 2.5 mU/kg fat-free mass per minute). Obese men and women were characterized as having a BMI of 28 or greater and body fat of 28% and 40% or greater for men and for women, respectively. Nonobese men and women had 22% and 35% or less body fat, respectively. All volunteers were Caucasian. Glucose disposal increased in a linear fashion with plasma insulin concentrations. The nonlinear suppression of plasma palmitate flux and concentrations could be linearized by logarithmically transforming both the insulin concentration and palmitate axes, except in nonobese men. We repeated the studies in 7 nonobese and 7 obese men, using 1.0 mU/kg fat-free mass per minute as the second insulin dose, which linearized the log-transformed lipolysis measures. The indices of insulin regulation of lipolysis predicted using 2 points (basal and second insulin dose) vs 3 points (basal, low, and high dose) were not different provided the proper second dose was selected. The EC(50) for insulin suppression of lipolysis correlated linearly with plasma triglycerides (r = 0.52, P < .001) and exponentially with insulin sensitivity(glucose) (r = 0.70, P < .001). We conclude that log transformation of insulin dose response data for FFA permits straightforward data analysis and simplifies the estimation of metabolically relevant parameters.

  1. The omega-3 fatty acid eicosapentaenoic acid is required for normal alcohol response behaviors in C. elegans.

    Directory of Open Access Journals (Sweden)

    Richard C Raabe

    Full Text Available Alcohol addiction is a widespread societal problem, for which there are few treatments. There are significant genetic and environmental influences on abuse liability, and understanding these factors will be important for the identification of susceptible individuals and the development of effective pharmacotherapies. In humans, the level of response to alcohol is strongly predictive of subsequent alcohol abuse. Level of response is a combination of counteracting responses to alcohol, the level of sensitivity to the drug and the degree to which tolerance develops during the drug exposure, called acute functional tolerance. We use the simple and well-characterized nervous system of Caenorhabditis elegans to model the acute behavioral effects of ethanol to identify genetic and environmental factors that influence level of response to ethanol. Given the strong molecular conservation between the neurobiological machinery of worms and humans, cellular-level effects of ethanol are likely to be conserved. Increasingly, variation in long-chain polyunsaturated fatty acid levels has been implicated in complex neurobiological phenotypes in humans, and we recently found that fatty acid levels modify ethanol responses in worms. Here, we report that 1 eicosapentaenoic acid, an omega-3 polyunsaturated fatty acid, is required for the development of acute functional tolerance, 2 dietary supplementation of eicosapentaenoic acid is sufficient for acute tolerance, and 3 dietary eicosapentaenoic acid can alter the wild-type response to ethanol. These results suggest that genetic variation influencing long-chain polyunsaturated fatty acid levels may be important abuse liability loci, and that dietary polyunsaturated fatty acids may be an important environmental modulator of the behavioral response to ethanol.

  2. Response of soybean seed germination to cadmium and acid rain.

    Science.gov (United States)

    Liu, Ting Ting; Wu, Peng; Wang, Li Hong; Zhou, Qing

    2011-12-01

    Cadmium (Cd) pollution and acid rain are the main environmental issues, and they often occur in the same agricultural region. Nevertheless, up to now, little information on the combined pollution of Cd(2+) and acid rain action on crops were presented. Here, we investigated the combined effect of Cd(2+) and acid rain on the seed germination of soybean. The results indicated that the single treatment with the low level of Cd(2+) (0.18, 1.0, 3.0 mg L(-1)) or acid rain (pH ≥3.0) could not affect the seed germination of soybean, which was resulted in the increased activities of peroxidase and catalase. The single treatment with the high concentration of Cd(2+) (>6 mg L(-1)) or acid rain at pH 2.5 decreased the activities of peroxidase and catalase, damaged the cell membrane and then decreased the seed germination of soybean. Meanwhile, the same toxic effect was observed in the combined treatment with Cd(2+) and acid rain, and the combined treatment had more toxic effect than the single treatment with Cd(2+) or acid rain. Thus, the combined pollution of Cd(2+) and acid rain had more potential threat to the seed germination of soybean than the single pollution of Cd(2+) or acid rain.

  3. Maximized PUFA measurements improve insight in changes in fatty acid composition in response to temperature

    NARCIS (Netherlands)

    Dooremalen, van C.; Pel, R.; Ellers, J.

    2009-01-01

    A general mechanism underlying the response of ectotherms to environmental changes often involves changes in fatty acid composition. Theory predicts that a decrease in temperature causes an increase in unsaturation of fatty acids, with an important role for long-chain poly-unsaturated fatty acids (P

  4. Arachidonic acid reduces the stress response of gilthead seabream Sparus aurata L.

    NARCIS (Netherlands)

    Anholt, R.D. van; Spanings, F.A.T.; Koven, W.M.; Nixon, O.; Wendelaar Bonga, S.E.

    2004-01-01

    In this study the influence of the dietary level of the fatty acid arachidonic acid (ArA, 20:4n-6) was determined on the acute stress response and osmoregulation of adult gilthead seabream Sparus aurata L. Seabream were fed a diet containing either 0.9% or 2.4% of total fatty acids as ArA for 18 day

  5. Airway responses to sulfate and sulfuric acid aerosols in asthmatics. An exposure-response relationship.

    Science.gov (United States)

    Utell, M J; Morrow, P E; Speers, D M; Darling, J; Hyde, R W

    1983-09-01

    Epidemiologic studies support an association between elevated levels of sulfates and increased symptoms in asthmatics. To determine if these pollutants produce airway responses, 17 asthmatics inhaled the following sulfates: sodium bisulfate, ammonium sulfate, ammonium bisulfate (NH4HSO4), or sulfuric acid (H2SO4) aerosols with an aerodynamic diameter of 0.80 micron at concentrations of 100 micrograms/m3, 450 micrograms/m3, and 1,000 micrograms/m3. A sodium chloride (NaCl) aerosol of similar characteristics, administered by double-blind randomization, served as a control. Subjects breathed these aerosols for a 16-minute period via a mouthpiece. Deposition studies showed 54 to 65% retention of the inhaled aerosols. At the 1,000 micrograms/m3 concentration, the Threshold Limit Value for occupational exposure, H2SO4 and NH4HSO4 inhalation produced significant reductions in specific airway conductance (SGaw) (p less than 0.05) and forced expiratory volume in one second (p less than 0.01) compared with NaCl or pre-exposure values. At the 450 micrograms/m3 concentration, only H2SO4 inhalation produced a significant reduction in SGaw (p less than 0.01). At 100 micrograms/m3, a level 3 to 5 times greater than peak urban levels, no significant change in airway function occurred after any sulfate exposure. These data indicate that asthmatics demonstrate bronchoconstriction after brief exposure to common acidic sulfate pollutants.

  6. Physiological and transcriptional responses and cross protection of Lactobacillus plantarum ZDY2013 under acid stress.

    Science.gov (United States)

    Huang, Renhui; Pan, Mingfang; Wan, Cuixiang; Shah, Nagendra P; Tao, Xueying; Wei, Hua

    2016-02-01

    Acid tolerance responses (ATR) in Lactobacillus plantarum ZDY2013 were investigated at physiological and molecular levels. A comparison of composition of cell membrane fatty acids (CMFA) between acid-challenged and unchallenged cells showed that acid adaptation evoked a significantly higher percentage of saturated fatty acids and cyclopropane fatty acids in acid-challenged than in unchallenged cells. In addition, reverse transcription-quantitative PCR analysis in acid-adapted cells at different pH values (ranging from 3.0 to 4.0) indicated that several genes were differently regulated, including those related to proton pumps, amino acid metabolism, sugar metabolism, and class I and class III stress response pathways. Expression of genes involved in fatty acid synthesis and production of alkali was significantly upregulated. Upon exposure to pH 4.5 for 2 h, a higher survival rate (higher viable cell count) of Lactobacillus plantarum ZDY2013 was achieved following an additional challenge to 40 mM hydrogen peroxide for 60 min, but no difference in survival rate of cells was found with further challenge to heat, ethanol, or salt. Therefore, we concluded that the physiological and metabolic changes of acid-treated cells of Lactobacillus plantarum ZDY2013 help the cells resist damage caused by acid, and further initiated global response signals to bring the whole cell into a state of defense to other stress factors, especially hydrogen peroxide.

  7. Family business: multiple members of major phytohormone classes orchestrate plant stress responses.

    Science.gov (United States)

    Erb, Matthias; Glauser, Gaetan

    2010-09-10

    Low-molecular-weight compounds such as jasmonic, abscisic and salicylic acids are commonly thought to be regulators of plant stress responses. However, it is becoming clear that these molecules, often referred to as phytohormones, are only a part of bigger groups of compounds with biological activity. We propose that the concept of "hormone families" may help to better understand plant physiological responses by taking into account not only the alleged main regulators, but also their precursors, conjugates and catabolites. Novel approaches to profile potentially active compounds in plants are discussed.

  8. Cyclopropanation of membrane unsaturated fatty acids is not essential to the acid stress response of Lactococcus lactis subsp. cremoris.

    Science.gov (United States)

    To, Thi Mai Huong; Grandvalet, Cosette; Tourdot-Maréchal, Raphaëlle

    2011-05-01

    Cyclopropane fatty acids (CFAs) are synthetized in situ by the transfer of a methylene group from S-adenosyl-L-methionine to a double bond of unsaturated fatty acid chains of membrane phospholipids. This conversion, catalyzed by the Cfa synthase enzyme, occurs in many bacteria and is recognized to play a key role in the adaptation of bacteria in response to a drastic perturbation of the environment. The role of CFAs in the acid tolerance response was investigated in the lactic acid bacterium Lactococcus lactis MG1363. A mutant of the cfa gene was constructed by allelic exchange. The cfa gene encoding the Cfa synthase was cloned and introduced into the mutant to obtain the complemented strain for homologous system studies. Data obtained by gas chromatography (GC) and GC-mass spectrometry (GC-MS) validated that the mutant could not produce CFA. The CFA levels in both the wild-type and complemented strains increased upon their entry to stationary phase, especially with acid-adapted cells or, more surprisingly, with ethanol-adapted cells. The results obtained by performing quantitative reverse transcription-PCR (qRT-PCR) experiments showed that transcription of the cfa gene was highly induced by acidity (by 10-fold with cells grown at pH 5.0) and by ethanol (by 9-fold with cells grown with 6% ethanol) in comparison with that in stationary phase. Cell viability experiments were performed after an acidic shock on the mutant strain, the wild-type strain, and the complemented strain, as a control. The higher viability level of the acid-adapted cells of the three strains after 3 h of shock proved that the cyclopropanation of unsaturated fatty acids is not essential for L. lactis subsp. cremoris survival under acidic conditions. Moreover, fluorescence anisotropy data showed that CFA itself could not maintain the membrane fluidity level, particularly with ethanol-grown cells.

  9. The upregulation of thiamine (vitamin B1) biosynthesis in Arabidopsis thaliana seedlings under salt and osmotic stress conditions is mediated by abscisic acid at the early stages of this stress response

    OpenAIRE

    Rapala-Kozik Maria; Wolak Natalia; Kujda Marta; Banas Agnieszka K

    2012-01-01

    Abstract Background Recent reports suggest that vitamin B1 (thiamine) participates in the processes underlying plant adaptations to certain types of abiotic and biotic stress, mainly oxidative stress. Most of the genes coding for enzymes involved in thiamine biosynthesis in Arabidopsis thaliana have been identified. In our present study, we examined the expression of thiamine biosynthetic genes, of genes encoding thiamine diphosphate-dependent enzymes and the levels of thiamine compounds duri...

  10. Plasma omega 3 polyunsaturated fatty acid status and monounsaturated fatty acids are altered by chronic social stress and predict endocrine responses to acute stress in titi monkeys

    Science.gov (United States)

    Disturbances in fatty acid (FA) metabolism may link chronic psychological stress, endocrine responsiveness, and psychopathology. Therefore, lipid metabolome-wide responses and their relationships with endocrine (cortisol; insulin; adiponectin) responsiveness to acute stress (AS) were assessed in a ...

  11. An alternative retinoic acid-responsive Stra6 promoter regulated in response to retinol deficiency.

    Science.gov (United States)

    Laursen, Kristian B; Kashyap, Vasundhra; Scandura, Joseph; Gudas, Lorraine J

    2015-02-13

    Cellular uptake of vitamin A (retinol) is essential for many biological functions. The Stra6 protein binds the serum retinol-binding protein, RBP4, and acts in conjunction with the enzyme lecithin:retinol acyltransferase to facilitate retinol uptake in some cell types. We show that in embryonic stem (ES) cells and in some tissues, the Stra6 gene encodes two distinct mRNAs transcribed from two different promoters. Whereas both are all-trans-retinoic acid (RA)-responsive in ES cells, the downstream promoter contains a half-site RA response element (RARE) and drives an ∼ 13-fold, RA-associated increase in luciferase reporter activity. We employed CRISPR-Cas9 genome editing to show that the endogenous RARE is required for RA-induced transcription of both Stra6 isoforms. We further demonstrate that in ES cells, 1) both RARγ and RXRα are present at the Stra6 RARE; 2) RA increases co-activator p300 (KAT3B) binding and histone H3 Lys-27 acetylation at both promoters; 3) RA decreases Suz12 levels and histone H3 Lys-27 trimethylation epigenetic marks at both promoters; and 4) these epigenetic changes are diminished in the absence of RARγ. In the brains of WT mice, both the longer and the shorter Stra6 transcript (Stra6L and Stra6S, respectively) are highly expressed, whereas these transcripts are found only at low levels in RARγ(-/-) mice. In the brains of vitamin A-deficient mice, both Stra6L and Stra6S levels are decreased. In contrast, in the vitamin A-deficient kidneys, the Stra6L levels are greatly increased, whereas Stra6S levels are decreased. Our data show that kidneys respond to retinol deficiency by differential Stra6 promoter usage, which may play a role in the retention of retinol when vitamin A is low.

  12. Photosynthetic and growth responses of Schima superba seedlings to sulfuric and nitric acid depositions.

    Science.gov (United States)

    Yao, Fang-Fang; Ding, Hui-Ming; Feng, Li-Li; Chen, Jing-Jing; Yang, Song-Yu; Wang, Xi-Hua

    2016-05-01

    A continuing rise in acid deposition can cause forest degradation. In China, acid deposition has converted gradually from sulfuric acid deposition (SAD) to nitric acid deposition (NAD). However, the differing responses of photosynthesis and growth to depositions of sulfuric vs. nitric acid have not been well studied. In this study, 1-year-old seedlings of Schima superba, a dominant species in subtropical forests, were treated with two types of acid deposition SO4 (2-)/NO3 (-) ratios (8:1 and 0.7:1) with two applications (foliar spraying and soil drenching) at two pH levels (pH 3.5 and pH 2.5) over a period of 18 months. The results showed that the intensity, acid deposition type, and spraying method had significant effects on the physiological characteristics and growth performance of seedlings. Acid deposition at pH 2.5 via foliar application reduced photosynthesis and growth of S. superba, especially in the first year. Unlike SAD, NAD with high acidity potentially alleviated the negative effects of acidity on physiological properties and growth, probably due to a fertilization effect that improved foliar nitrogen and chlorophyll contents. Our results suggest that trees were damaged mainly by direct acid stress in the short term, whereas in the long term, soil acidification was also likely to be a major risk to forest ecosystems. Our data suggest that the shift in acid deposition type may complicate the ongoing challenge of anthropogenic acid deposition to ecosystem stability.

  13. Blood ketone response to norepinephrine-induced free fatty acid in diabetes

    Energy Technology Data Exchange (ETDEWEB)

    Blackard, W.G.; Omori, Yoshiaki

    1963-04-18

    During 90-minute norepinephrine infusions, blood free fatty acid and ketone responses of Japanese nondiabetic and diabetic subjects were determined. Nonobese diabetic subjects with and without fasting hyperglycemia demonstrated significantly greater blood ketone elevations than nondiabetics. An inverse correlation between obesity and blood ketone response to nonrepinephrine was observed in diabetics. This correlation could not be attributed to varying degrees of fasting hyperglycemia or free fatty acid elevation. Nonobese diabetics with mild fasting hyperglycemia (90 to 150 mg%) exhibited an unexpected greater increase in blood ketones than nonobese diabetics with moderate fasting hyperglycemia (150 to 250 mg%). Differences in free fatty acid elevations were not responsible for this apparent paradox. The magnitude of the hyperketonemic response, though dependent on free fatty elevation, seemed more sensitive to the degree of obesity and the fasting blood glucose level. Fractional ketone body measurements attributed the blood ketone elevations predominantly to ..beta..-hydroxybutyric acid increases. 43 references, 6 figures, 1 table.

  14. Fade and tachyphylaxis of gastric acid secretory response to pentagastrin in rat isolated gastric mucosa.

    Science.gov (United States)

    Hirst, B H; Holland, J; Parsons, M E; Price, C A

    1988-12-01

    1. Gastric acid secretory responses to pentagastrin were characterized in the rat isolated gastric mucosa. In particular, the mechanisms underlying fade, declining response upon continued stimulation, and tachyphylaxis, progressively reduced responses upon repeated stimulation, were investigated. 2. Pentagastrin, 10(-9)-10(-7) M, resulted in concentration-related increases in acid secretion, with a mean maximum of 2.65 mumol cm-2 h-1 in response to pentagastrin, 10(-7) M. Higher concentrations of pentagastrin produced sub-maximal secretory rates; we define this as auto-inhibition. The responses to all concentrations of pentagastrin demonstrated fade. The rate of fade was correlated with the maximum acid secretory rate, declining at about 36% of the peak over the first 16 min. 3. The PO2, PCO2, [HCO3-], pH, [glucose], [lactate], [Na+] and [K+] did not decline during the fade of the acid secretory response to pentagastrin, 10(-7) M. Addition of a second aliquot of pentagastrin was not able to reverse fade, but these tissues were responsive to histamine. Replacement of the serosal solution, before addition of a second aliquot of pentagastrin, increased the acid response from 3% to 24% of the first response. 4. Serosal solution from donor tissues, allowed to respond to pentagastrin and then the acid secretion to fade, was able to stimulate secretion in fresh recipient tissues, although at lower rates. 5. Acid secretory responses to a second dose of pentagastrin were not significantly different, whether the tissues were previously unstimulated, or stimulated with pentagastrin washed out after attaining its peak secretory response (after 10-20 min). The second response was significantly reduced if the first response was allowed to fade with the pentagastrin in contact for 100 min; i.e. fade significantly influenced the extent of tachyphylaxis. 6. Proglumide, 10(-2) M, a gastrin receptor antagonist, and omeprazole, 10(-5) M, an inhibitor of the gastric (H+ + K

  15. Responses to Gamma-Aminobutyric Acid of Rat Visual Cortical Neurons in Tissue Slices

    Science.gov (United States)

    1986-04-01

    Neurol. 234: 242-263. Peters, A. and Proskauer, c. C. (1980) Synaptic relationships between a multipolar stellate cell and a pyramidal neuron in rat...APR 1986 2. REPORT TYPE N/A 3. DATES COVERED - 4. TITLE AND SUBTITLE Responses to Gamma-Aminobutyric Acid of Rat Visual Cortical Neurons in...AIR FORCE MEDICAL CENTER Title of Thesis: Responses to Gamma-Aminobutyric Acid of Rat Visual Cortical Neurons in Tissue Slices Name of Candidate

  16. Characterization of the Shewanella oneidensis Fur gene: roles in iron and acid tolerance response

    OpenAIRE

    Wu Liyou; Luo Feng; Harris Daniel P; Yang Yunfeng; Parsons Andrea B; Palumbo Anthony V; Zhou Jizhong

    2008-01-01

    Abstract Background Iron homeostasis is a key metabolism for most organisms. In many bacterial species, coordinate regulation of iron homeostasis depends on the protein product of a Fur gene. Fur also plays roles in virulence, acid tolerance, redox-stress responses, flagella chemotaxis and metabolic pathways. Results We conducted physiological and transcriptomic studies to characterize Fur in Shewanella oneidensis, with regard to its roles in iron and acid tolerance response. A S. oneidensisf...

  17. Silencing the SpMPK1, SpMPK2, and SpMPK3 Genes in Tomato Reduces Abscisic Acid—Mediated Drought Tolerance

    Directory of Open Access Journals (Sweden)

    Yan Liang

    2013-11-01

    Full Text Available Drought is a major threat to agriculture production worldwide. Mitogen-activated protein kinases (MAPKs play a pivotal role in sensing and converting stress signals into appropriate responses so that plants can adapt and survive. To examine the function of MAPKs in the drought tolerance of tomato plants, we silenced the SpMPK1, SpMPK2, and SpMPK3 genes in wild-type plants using the virus-induced gene silencing (VIGS method. The results indicate that silencing the individual genes or co-silencing SpMPK1, SpMPK2, and SpMPK3 reduced the drought tolerance of tomato plants by varying degrees. Co-silencing SpMPK1 and SpMPK2 impaired abscisic acid (ABA-induced and hydrogen peroxide (H2O2-induced stomatal closure and enhanced ABA-induced H2O2 production. Similar results were observed when silencing SpMPK3 alone, but not when SpMPK1 and SpMPK2 were individually silenced. These data suggest that the functions of SpMPK1 and SpMPK2 are redundant, and they overlap with that of SpMPK3 in drought stress signaling pathways. In addition, we found that SpMPK3 may regulate H2O2 levels by mediating the expression of CAT1. Hence, SpMPK1, SpMPK2, and SpMPK3 may play crucial roles in enhancing tomato plants’ drought tolerance by influencing stomatal activity and H2O2 production via the ABA-H2O2 pathway.

  18. Maximized PUFA measurements improve insight in changes in fatty acid composition in response to temperature.

    Science.gov (United States)

    van Dooremalen, Coby; Pel, Roel; Ellers, Jacintha

    2009-10-01

    A general mechanism underlying the response of ectotherms to environmental changes often involves changes in fatty acid composition. Theory predicts that a decrease in temperature causes an increase in unsaturation of fatty acids, with an important role for long-chain poly-unsaturated fatty acids (PUFAs). However, PUFAs are particularly unstable and susceptible to peroxidation, hence subtle differences in fatty acid composition can be challenging to detect. We determined the fatty acid composition in springtail (Collembola) in response to two temperatures (5 degrees C and 25 degrees C). First, we tested different sample preparation methods to maximize PUFAs. Treatments consisted of different solvents for primary lipid extraction, mixing with antioxidant, flushing with inert gas, and using different temperature exposures during saponification. Especially slow saponification at low temperature (90 min at 70 degrees C) in combination with replacement of headspace air with nitrogen during saponification and methylation maximized PUFAs for GC analysis. Applying these methods to measure thermal responses in fatty acid composition, the data showed that the (maximized) proportion of C(20) PUFAs increased at low acclimation temperature. However, C(18) PUFAs increased at high acclimation temperature, which is contrary to expectations. Our study illustrates that PUFA levels in lipids may often be underestimated and this may hamper a correct interpretation of differential responses of fatty acid composition.

  19. A chloroplast lipoxygenase is required for wound-induced jasmonic acid accumulation in Arabidopsis.

    Science.gov (United States)

    Bell, E; Creelman, R A; Mullet, J E

    1995-09-12

    Plant lipoxygenases are thought to be involved in the biosynthesis of lipid-derived signaling molecules. The potential involvement of a specific Arabidopsis thaliana lipoxygenase isozyme, LOX2, in the biosynthesis of the plant growth regulators jasmonic acid (JA) and abscisic acid was investigated. Our characterization of LOX2 indicates that the protein is targeted to chloroplasts. The physiological role of this chloroplast lipoxygenase was analyzed in transgenic plants where cosuppression reduced LOX2 accumulation. The reduction in LOX2 levels caused no obvious changes in plant growth or in the accumulation of abscisic acid. However, the wound-induced accumulation of JA observed in control plants was absent in leaves of transgenic plants that lacked LOX2. Thus, LOX2 is required for the wound-induced synthesis of the plant growth regulator JA in leaves. We also examined the expression of a wound- and JA-inducible Arabidopsis gene, vsp, in transgenic and control plants. Leaves of transgenic plants lacking LOX2 accumulated less vsp mRNA than did control leaves in response to wounding. This result suggests that wound-induced JA (or some other LOX2-requiring component of the wound response pathway) is involved in the wound-induced regulation of this gene.

  20. Antifungal Activity and Biochemical Response of Cuminic Acid against Phytophthora capsici Leonian

    Directory of Open Access Journals (Sweden)

    Yong Wang

    2016-06-01

    Full Text Available Phytophthora blight of pepper caused by Phytophthora capsici Leonian is a destructive disease throughout the world. Cuminic acid, extracted from the seed of Cuminum cyminum L., belongs to the benzoic acid chemical class. In this study, the sensitivity and biochemical response of P. capsici to cuminic acid was determined. The mean EC50 (50% effective concentration values for cuminic acid in inhibiting mycelial growth and zoospore germination of the 54 studied P. capsici isolates were 14.54 ± 5.23 μg/mL and 6.97 ± 2.82 μg/mL, respectively. After treatment with cuminic acid, mycelial morphology, sporangium formation and mycelial respiration were significantly influenced; cell membrane permeability and DNA content increased markedly, but pyruvic acid content, adenosine triphosphate (ATP content, and ATPase activity decreased compared with the untreated control. In pot experiments, cuminic acid exhibited both protective and curative activity. Importantly, POD and PAL activity of the pepper leaves increased after being treated with cuminic acid. These indicated that cuminic acid not only showed antifungal activity, but also could improve the defense capacity of the plants. All the results suggested that cuminic acid exhibits the potential to be developed as a new phytochemical fungicide, and this information increases our understanding of the mechanism of action of cuminic acid against Phytophthora capsici.

  1. Human monocyte differentiation stage affects response to arachidonic acid.

    Science.gov (United States)

    Escobar-Alvarez, Elizabeth; Pelaez, Carlos A; García, Luis F; Rojas, Mauricio

    2010-01-01

    AA-induced cell death mechanisms acting on human monocytes and monocyte-derived macrophages (MDM), U937 promonocytes and PMA-differentiated U937 cells were studied. Arachidonic acid induced apoptosis and necrosis in monocytes and U937 cells but only apoptosis in MDM and U937D cells. AA increased both types of death in Mycobacterium tuberculosis-infected cells and increased the percentage of TNFalpha+ cells and reduced IL-10+ cells. Experiments blocking these cytokines indicated that AA-mediated death was TNFalpha- and IL-10-independent. The differences in AA-mediated cell death could be explained by high ROS, calpain and sPLA-2 production and activity in monocytes. Blocking sPLA-2 in monocytes and treatment with antioxidants favored M. tuberculosis control whereas AA enhanced M. tuberculosis growth in MDM. Such evidence suggested that AA-modulated effector mechanisms depend on mononuclear phagocytes' differentiation stage.

  2. Metabolomics reveals amino acids contribute to variation in response to simvastatin treatment.

    Directory of Open Access Journals (Sweden)

    Miles Trupp

    Full Text Available UNLABELLED: Statins are widely prescribed for reducing LDL-cholesterol (C and risk for cardiovascular disease (CVD, but there is considerable variation in therapeutic response. We used a gas chromatography-time-of-flight mass-spectrometry-based metabolomics platform to evaluate global effects of simvastatin on intermediary metabolism. Analyses were conducted in 148 participants in the Cholesterol and Pharmacogenetics study who were profiled pre and six weeks post treatment with 40 mg/day simvastatin: 100 randomly selected from the full range of the LDL-C response distribution and 24 each from the top and bottom 10% of this distribution ("good" and "poor" responders, respectively. The metabolic signature of drug exposure in the full range of responders included essential amino acids, lauric acid (p<0.0055, q<0.055, and alpha-tocopherol (p<0.0003, q<0.017. Using the HumanCyc database and pathway enrichment analysis, we observed that the metabolites of drug exposure were enriched for the pathway class amino acid degradation (p<0.0032. Metabolites whose change correlated with LDL-C lowering response to simvastatin in the full range responders included cystine, urea cycle intermediates, and the dibasic amino acids ornithine, citrulline and lysine. These dibasic amino acids share plasma membrane transporters with arginine, the rate-limiting substrate for nitric oxide synthase (NOS, a critical mediator of cardiovascular health. Baseline metabolic profiles of the good and poor responders were analyzed by orthogonal partial least square discriminant analysis so as to determine the metabolites that best separated the two response groups and could be predictive of LDL-C response. Among these were xanthine, 2-hydroxyvaleric acid, succinic acid, stearic acid, and fructose. Together, the findings from this study indicate that clusters of metabolites involved in multiple pathways not directly connected with cholesterol metabolism may play a role in modulating

  3. Dietary fatty acids and the stress response of fish : arachidonic acid in seabream and tilapia

    NARCIS (Netherlands)

    Anholt, Rogier Daniël van

    2004-01-01

    A key factor in the production of fish in commercial aquaculture is the optimization of the artificial diets, not only to achieve optimal growth, but also to maximize fish health. Evidence is accumulating that dietary lipids, particularly the fatty acid composition, can have a direct effect on the f

  4. Sugar-Responsive Pseudopolyrotaxane Composed of Phenylboronic Acid-Modified Polyethylene Glycol and γ-Cyclodextrin

    Directory of Open Access Journals (Sweden)

    Tomohiro Seki

    2015-03-01

    Full Text Available We have designed a sugar-responsive pseudopolyrotaxane (PPRX by combining phenylboronic acid-modified polyethylene glycol (PBA–PEG and γ-cyclodextrin. Phenylboronic acid (PBA was used as a sugar-recognition motif in the PPRX because PBA reacts with a diol portion of the sugar molecule and forms a cyclic ester. When D-fructose or D-glucose was added to a suspension of PPRX, PPRX disintegrated, depending on the concentration of the sugars. Interestingly, catechol does not show a response although catechol has a high affinity for PBA. We analyzed the response mechanism of PPRX by considering equilibria.

  5. Regulation of intestinal IgA responses by dietary palmitic acid and its metabolism.

    Science.gov (United States)

    Kunisawa, Jun; Hashimoto, Eri; Inoue, Asuka; Nagasawa, Risa; Suzuki, Yuji; Ishikawa, Izumi; Shikata, Shiori; Arita, Makoto; Aoki, Junken; Kiyono, Hiroshi

    2014-08-15

    Enhancement of intestinal IgA responses is a primary strategy in the development of oral vaccine. Dietary fatty acids are known to regulate host immune responses. In this study, we show that dietary palmitic acid (PA) and its metabolites enhance intestinal IgA responses. Intestinal IgA production was increased in mice maintained on a PA-enriched diet. These mice also showed increased intestinal IgA responses against orally immunized Ag, without any effect on serum Ab responses. We found that PA directly stimulates plasma cells to produce Ab. In addition, mice receiving a PA-enriched diet had increased numbers of IgA-producing plasma cells in the large intestine; this effect was abolished when serine palmitoyltransferase was inhibited. These findings suggest that dietary PA regulates intestinal IgA responses and has the potential to be a diet-derived mucosal adjuvant.

  6. Plasma vanillylmandelic acid level as an index of psychological stress response in normal subjects.

    Science.gov (United States)

    Fukuda, M; Hata, A; Niwa, S; Hiramatsu, K; Honda, H; Nakagome, K; Iwanami, A

    1996-06-26

    The relationships between psychological stress responses and plasma levels of vanillylmandelic acid (VMA), 3-methoxy-4-hydroxyphenylglycol (MHPG), homovanillic acid (HVA), and 5-hydroxyindolacetic acid (5-HIAA) were investigated in normal volunteers. Two questionnaires were used to measure stress: the Psychological Stress Response Scale (PSRS) and the State-Trait Anxiety Inventory (STAI). Plasma levels of VMA--but not MHPG, HVA, and 5-HIAA--showed significant positive correlations with PSRS emotional and cognitive-behavioral stress and STAI state anxiety. Significant positive correlations were also found between plasma levels of VMA and MHPG and psychological stress responses measured repeatedly in a longitudinal study of an Olympic swimmer. Plasma VMA measurements, which reflect the level of activity of the peripheral sympathetic nervous system, may provide a useful biochemical index of psychological stress responses in normal subjects.

  7. Response of Chlamydomonas reinhardtii to naphthenic acid exposure

    Energy Technology Data Exchange (ETDEWEB)

    Goff, K.; Wilson, K. [Saskatchewan Univ., Saskatoon, SK (Canada); Headley, J. [Environment Canada, Ottawa, ON (Canada)

    2010-07-01

    This study examined the feasibility of using a model organism for the algal bioremediation of oil sands process water (OSPW), a highly toxic mixture of sediments, bitumen, ions, and organic and inorganic compounds. Naphthenic acids (NAs) are a contaminant class of particular concern. Bioremediation techniques may mitigate toxicity of OSPW in general, and NAs in particular. Although most studies on the biodegradation of NAs focus on the role of bacteria, fungi, and emergent macrophytes, studies have indicated that algae may also play a key role through direct degradation, biosequestration, or photosynthetic aeration of waters to promote other biological reactions. Chlamydomonas frigida is of particular interest, but no cultures are currently available. Therefore, this study used C. reinhardtii, a well-characterized model organism, to begin analysis of potential algal bioremediation of OSPW. Cultures of C. reinhardtii were grown heterotrophically in nutrient media spiked with a dilution series of NAs. Culture densities were measured to compile growth curves over time, changes in rate of growth, and survivability. Negative ion electrospray mass spectrometry was used to determine the concentration of NAs in solution in relation to growth rate and culture density. The study determined the tolerance of C. reinhardtii to NAs. A mechanism for this tolerance was then proposed.

  8. Primary and secondary genetic responses after folic acid-induced acute renal injury in the mouse.

    Science.gov (United States)

    Calvet, J P; Chadwick, L J

    1994-12-01

    Folic acid-induced acute renal injury results in dramatic changes in gene expression. Among the genes affected by folic acid treatment are the primary response genes, c-fos and c-myc, which are thought to function to initiate cell cycle events. In this report, changes in the expression of three other genes in response to folic acid injury have been investigated: ornithine decarboxylase, epidermal growth factor (EGF), and sulfated glycoprotein-2 (SGP-2). Renal injury was found to cause a rapid decrease in EGF mRNA, which remained absent for several days after the initial injury, gradually returning to normal levels over an approximately 3-wk regeneration and recovery period. Ornithine decarboxylase mRNA showed a similar decrease. In contrast, folic acid caused a rapid increase in SGP-2 mRNA, which peaked several days after treatment, decreasing to normal levels over the 3-wk period. The mRNAs for the primary response genes were superinduced in the injured kidneys in the presence of the protein synthesis inhibitor cycloheximide. In contrast, the changes in EGF and SGP-2 mRNA levels were blocked by cycloheximide, indicating that these responses required new protein synthesis during the first few hours after folic acid injury. The opposite but parallel responses in the expression of the EGF and SGP-2 genes suggest that their regulation is coupled to the initial injury-induced dedifferentiation and subsequent return to the fully differentiated state.

  9. Individual variation in lipidomic profiles of healthy subjects in response to omega-3 Fatty acids.

    Directory of Open Access Journals (Sweden)

    Malin L Nording

    Full Text Available INTRODUCTION: Conflicting findings in both interventional and observational studies have resulted in a lack of consensus on the benefits of ω3 fatty acids in reducing disease risk. This may be due to individual variability in response. We used a multi-platform lipidomic approach to investigate both the consistent and inconsistent responses of individuals comprehensively to a defined ω3 intervention. METHODS: The lipidomic profile including fatty acids, lipid classes, lipoprotein distribution, and oxylipins was examined multi- and uni-variately in 12 healthy subjects pre vs. post six weeks of ω3 fatty acids (1.9 g/d eicosapentaenoic acid [EPA] and 1.5 g/d docosahexaenoic acid [DHA]. RESULTS: Total lipidomic and oxylipin profiles were significantly different pre vs. post treatment across all subjects (p=0.00007 and p=0.00002 respectively. There was a strong correlation between oxylipin profiles and EPA and DHA incorporated into different lipid classes (r(2=0.93. However, strikingly divergent responses among individuals were also observed. Both ω3 and ω6 fatty acid metabolites displayed a large degree of variation among the subjects. For example, in half of the subjects, two arachidonic acid cyclooxygenase products, prostaglandin E2 (PGE2 and thromboxane B2 (TXB2, and a lipoxygenase product, 12-hydroxyeicosatetraenoic acid (12-HETE significantly decreased post intervention, whereas in the other half they either did not change or increased. The EPA lipoxygenase metabolite 12-hydroxyeicosapentaenoic acid (12-HEPE varied among subjects from an 82% decrease to a 5,000% increase. CONCLUSIONS: Our results show that certain defined responses to ω3 fatty acid intervention were consistent across all subjects. However, there was also a high degree of inter-individual variability in certain aspects of lipid metabolism. This lipidomic based phenotyping approach demonstrated that individual responsiveness to ω3 fatty acids is highly variable and

  10. Increased acid responsiveness in vagal sensory neurons in a guinea pig model of eosinophilic esophagitis.

    Science.gov (United States)

    Hu, Youtian; Liu, Zhenyu; Yu, Xiaoyun; Pasricha, Pankaj J; Undem, Bradley J; Yu, Shaoyong

    2014-07-15

    Eosinophilic esophagitis (EoE) is characterized with eosinophils and mast cells predominated allergic inflammation in the esophagus and present with esophageal dysfunctions such as dysphagia, food impaction, and heartburn. However, the underlying mechanism of esophageal dysfunctions is unclear. This study aims to determine whether neurons in the vagal sensory ganglia are modulated in a guinea pig model of EoE. Animals were actively sensitized by ovalbumin (OVA) and then challenged with aerosol OVA inhalation for 2 wk. This results in a mild esophagitis with increases in mast cells and eosinophils in the esophageal wall. Vagal nodose and jugular neurons were disassociated, and their responses to acid, capsaicin, and transient receptor potential vanilloid type 1 (TRPV1) antagonist AMG-9810 were studied by calcium imaging and whole cell patch-clamp recording. Compared with naïve animals, antigen challenge significantly increased acid responsiveness in both nodose and jugular neurons. Their responses to capsaicin were also increased after antigen challenge. AMG-9810, at a concentration that blocked capsaicin-evoked calcium influx, abolished the increase in acid-induced activation in both nodose and jugular neurons. Vagotomy strongly attenuated those increased responses of nodose and jugular neurons to both acid and capsaicin induced by antigen challenge. These data for the first time demonstrated that prolonged antigen challenge significantly increases acid responsiveness in vagal nodose and jugular ganglia neurons. This sensitization effect is mediated largely through TRPV1 and initiated at sensory nerve endings in the peripheral tissues. Allergen-induced enhancement of responsiveness to noxious stimulation by acid in sensory nerve may contribute to the development of esophageal dysfunctions such as heartburn in EoE.

  11. Human pulp response to acid pretreatment of dentin and to composite restoration.

    Science.gov (United States)

    Stanley, H R; Going, R E; Chauncey, H H

    1975-10-01

    The newer composites, although free of methacrylic acid and of a neutral pH, were still found to be toxic to the pulp. The intensity of response was increased after acid pretreatment procedures; this indicates an increase in dentin permeability. When the remaining dentin thickness was 1.0 mm or less, regardless of whether the dentin was primary dentin or primary and reparative dentin, the percentage of teeth with abscess formations increased. Use of calcium hydroxide bases or liners to coat the dentin before acid pretreatment of enamel is therefore highly recommended.

  12. Acclimation of croton and hibiscus seedlings in response to the application of indobultiric acid and humic acid for rooting

    Directory of Open Access Journals (Sweden)

    Lílian Estrela Borges Baldotto

    2015-06-01

    Full Text Available The vegetative propagation of ornamental plants can be accelerated by applying plant growth regulators. Amongst them, the use of auxins, plant hormones with physiological effects on cell elongation and rooting have stood out. Alternatively, the application of humic acids, bioactive fraction of soil organic matter, also results in increases in rooting cuttings of ornamental plants. The objective of this work was to study the growth characteristics and the nutritional contents of croton and hibiscus plants during acclimation of seedlings in response to different concentrations of indolebutyric acid (IBA and humic acid (HA applied to cuttings for rooting. The experiment was conducted in greenhouse, and the apical stem cuttings were treated with solutions with concentrations of 0, 250, 500, 1000 and 2000 mg L-1of IBA and 0, 10, 20, 30 and 40 mg L-1 of C from HA. At 45 days of rooting in carbonized rice husk, they were individually transferred to plastic bags of 2.0 dm3 containing a mixture of soil: sand: manure (2: 1: 1 as substrate. At 90 days of acclimation, the plants were collected for measurement of growth and nutritional variables. The results showed that the application of the IBA stimulates the absorption of nutrients and growth of croton cuttings and transplanted hibiscus, contributing to formation of vigorous seedlings. A similar response occurred with the application of HA in hibiscus cuttings

  13. pH-responsive fatty acid self-assembly transition induced by UV light.

    Science.gov (United States)

    Arnould, Audrey; Gaillard, Cedric; Fameau, Anne-Laure

    2015-11-15

    Fatty acids are natural, pH-responsive surfactants. Their properties can be tuned by adding CO2 or by applying light which modify solution pH. We investigated photoresponsive systems based on fatty acids with different chain lengths in the presence of a photoacid generator (PAG). Under UV irradiation, photolysis of the PAG in aqueous solution resulted in a decrease in pH, triggering a change in fatty acid assembly. Using a multi-scale approach before and after UV irradiation, we characterized the effect of this pH decrease on the nature of the fatty acid self-assemblies. At the molecular scale, pH and infrared spectroscopy measurements were used to determine the fatty acid ionization state. At the microscopic scale, the self-assembled structure was characterized using small-angle neutron scattering and microscopy. We showed that UV irradiation tuned the ionization state of the fatty acid molecules which in turn triggered a transition from spherical micelles to vesicles or lamellar phases, depending on fatty acid chain length. We studied the foaming properties of these systems before and after UV irradiation. We showed that after UV irradiation, foam stability was drastically enhanced as a result of a change in self-assembly. Our approach can be easily extended to various pH-responsive surfactants.

  14. AUXIN RESPONSE FACTOR 2 Intersects Hormonal Signals in the Regulation of Tomato Fruit Ripening.

    Science.gov (United States)

    Breitel, Dario A; Chappell-Maor, Louise; Meir, Sagit; Panizel, Irina; Puig, Clara Pons; Hao, Yanwei; Yifhar, Tamar; Yasuor, Hagai; Zouine, Mohamed; Bouzayen, Mondher; Granell Richart, Antonio; Rogachev, Ilana; Aharoni, Asaph

    2016-03-01

    The involvement of ethylene in fruit ripening is well documented, though knowledge regarding the crosstalk between ethylene and other hormones in ripening is lacking. We discovered that AUXIN RESPONSE FACTOR 2A (ARF2A), a recognized auxin signaling component, functions in the control of ripening. ARF2A expression is ripening regulated and reduced in the rin, nor and nr ripening mutants. It is also responsive to exogenous application of ethylene, auxin and abscisic acid (ABA). Over-expressing ARF2A in tomato resulted in blotchy ripening in which certain fruit regions turn red and possess accelerated ripening. ARF2A over-expressing fruit displayed early ethylene emission and ethylene signaling inhibition delayed their ripening phenotype, suggesting ethylene dependency. Both green and red fruit regions showed the induction of ethylene signaling components and master regulators of ripening. Comprehensive hormone profiling revealed that altered ARF2A expression in fruit significantly modified abscisates, cytokinins and salicylic acid while gibberellic acid and auxin metabolites were unaffected. Silencing of ARF2A further validated these observations as reducing ARF2A expression let to retarded fruit ripening, parthenocarpy and a disturbed hormonal profile. Finally, we show that ARF2A both homodimerizes and interacts with the ABA STRESS RIPENING (ASR1) protein, suggesting that ASR1 might be linking ABA and ethylene-dependent ripening. These results revealed that ARF2A interconnects signals of ethylene and additional hormones to co-ordinate the capacity of fruit tissue to initiate the complex ripening process.

  15. Solar sterilization of abscised fruit: a cultural practice to reduce infestations of Anastrepha obliqua around orchards

    Science.gov (United States)

    Abscised mangoes, Mangifera indica L., of several varieties were stored under varying conditions of insolation, including no sun (stored in a laboratory), shade (stored under the shade of a mango tree), full sun (stored in direct view of the sun), and covered in a black plastic bag and stored in dir...

  16. Modelling of the simultaneous photodegradation of Acid Red 97, Acid Orange 61 and Acid Brown 425 using factor screening and response surface strategies.

    Science.gov (United States)

    Fernández, Cristina; Larrechi, M Soledad; Callao, M Pilar

    2010-08-15

    In this paper the influence of seven variables that could be relevant in the photodegradation of three textile dyes - Acid Red 97, Acid Orange 61 and Acid Brown 425 - has been studied with the aim of determining the most efficient conditions for this process. The type and concentration of catalyst, the presence and concentration of H(2)O(2), the stirring, the pH and the dye concentration have been studied as variables. In the first stage the more basic variables were analyzed using a screening methodology (saturated fractional factorial design) and it was concluded that the most influential variable was the presence of H(2)O(2). In the second stage, a central composite design was used to establish a response surface for the behavior of the photodegradation. In this stage the concentration of Acid Brown 425 was fixed and the degradation was carried out without catalyst. The most remarkable aspects of the experiment are that brown dye is always the most persistent in the solution and that a catalyst is not needed to degrade the dyes quickly. A second-order equation is needed to model this process. The response surface obtained could be useful for reducing the time and money needed to treat effluent wastewater.

  17. The response of quartz crystals coated with thin fatty acid film to organic gases

    CERN Document Server

    Jin, C N; Kim, K H; Kwon, Y S

    1999-01-01

    We tried to apply a quartz crystal as a sensor by using the resonant frequency and the resistance properties of quartz crystals. Four kinds of fatty acids that have the same head groups were coated on the surfaces of the quartz crystals, and the shift of the resonant frequency and the resistance were observed based on the lengths of the tail groups. Myristic acid (C sub 1 sub 4), palmitic acid (C sub 1 sub 6), stearic acid (C sub 1 sub 8), and arachidic acid (C sub 2 sub 0) were deposited on the surfaces of quartz crystals by using the Langmuir-Blodgett (LB) method. As a result, the resonant frequency change was more sensitive to high molecular-weight fatty acids than to low molecular-weight ones. We also observed the effect of temperature on stearic acid LB films, and the response properties of quartz crystals coated with stearic-acid LB films to organic gases were investigated. As a result, the sensitivity of quartz crystals to organic gases was higher for higher molecular-weight gas, and we found that quar...

  18. Good and bad protons: genetic aspects of acidity stress responses in plants.

    Science.gov (United States)

    Shavrukov, Yuri; Hirai, Yoshihiko

    2016-01-01

    Physiological aspects of acidity stress in plants (synonymous with H(+) rhizotoxicity or low-pH stress) have long been a focus of research, in particular with respect to acidic soils where aluminium and H(+) rhizotoxicities often co-occur. However, toxic H(+) and Al(3+) elicit different response mechanisms in plants, and it is important to consider their effects separately. The primary aim of this review was to provide the current state of knowledge regarding the genetics of the specific reactions to low-pH stress in growing plants. A comparison of the results gleaned from quantitative trait loci analysis and global transcriptome profiling of plants in response to high proton concentrations revealed a two-stage genetic response: (i) in the short-term, proton pump H(+)-ATPases present the first barrier in root cells, allocating an excess of H(+) into either the apoplast or vacuole; the ensuing defence signaling system involves auxin, salicylic acid, and methyl jasmonate, which subsequently initiate expression of STOP and DREB transcription factors as well as chaperone ROF; (2) the long-term response includes other genes, such as alternative oxidase and type II NAD(P)H dehydrogenase, which act to detoxify dangerous reactive oxygen species in mitochondria, and help plants better manage the stress. A range of transporter genes including those for nitrate (NTR1), malate (ALMT1), and heavy metals are often up-regulated by H(+) rhizotoxicity. Expansins, cell-wall-related genes, the γ-aminobutyric acid shunt and biochemical pH-stat genes also reflect changes in cell metabolism and biochemistry in acidic conditions. However, the genetics underlying the acidity stress response of plants is complicated and only fragmentally understood.

  19. Effect of bunch sanitation on spatial distributions of abscised fruit and phycitine moths (Lepidoptera: Pyralidae) in California date gardens.

    Science.gov (United States)

    Nay, Justin E; Park, Yong-Lak; Perring, Thomas M

    2007-12-01

    Phycitine moths are an economic impediment to California date, Phoenix dactylifera L., production. Summer populations build to damaging levels on abscised dates that get trapped in fruit bunches. This study was conducted to determine the relationship between abscised fruit and moth infestation, and to evaluate changes in the spatial distribution of abscised fruit and moth-infested fruit after a bunch-sanitation treatment. Over the 9 wk of this study, there was a 69.9% reduction in the number of moth-infested fruit after a single sanitation treatment. Linear regression analysis showed a significant relationship between abscised fruit and phycitine moth-infested fruit; 42 and 76.6% of the variation in the number of infested fruit was explained by the number of abscised fruit in noncleaned and cleaned plots, respectively. The pattern of reinfestation by moths over the 9 wk posttreatment period was analyzed with spatial analysis with distance indices. Significant spatial associations were found between abscised fruit and moth-infested fruit, supporting the regression analysis. The sanitation treatments caused significant gaps in both abscised fruit and moth-infested fruit. Over time, gap sizes became smaller, indicating a nonrandom pattern of reinfestation that likely was caused by the movement of moths from nontreated areas into treated areas. This study, the first spatial analysis conducted in dates, suggests that in-season bunch sanitation could be effective at reducing summer moth densities if applied on a large regional scale.

  20. Dietary Fatty Acids and Immune Response to Food-Borne Bacterial Infections

    OpenAIRE

    2013-01-01

    Functional innate and acquired immune responses are required to protect the host from pathogenic bacterial infections. Modulation of host immune functions may have beneficial or deleterious effects on disease outcome. Different types of dietary fatty acids have been shown to have variable effects on bacterial clearance and disease outcome through suppression or activation of immune responses. Therefore, we have chosen to review research across experimental models and food sources on the effec...

  1. Response of sedimentary nucleic acids to benthic disturbance in the Central Indian Basin

    Digital Repository Service at National Institute of Oceanography (India)

    Fernandes, C.E.G.; DeSouza, M.J.B.D.; Nair, S.; LokaBharathi, P.A.

    Information on the response of nucleic acids (i.e., DNA and RNA) to simulated benthic disturbance was obtained from samples collected from eight sediment cores (0-10 cm) located in the Central Indian Basin (CIB). In general the total sedimentary DNA...

  2. NF1 Is a Tumor Suppressor in Neuroblastoma that Determines Retinoic Acid Response and Disease Outcome

    NARCIS (Netherlands)

    M. Hölzel; S. Huang; J. Koster; I. Ora; A. Lakeman; H. Caron; W. Nijkamp; J. Xie; T. Callens; S. Asgharzadeh; R.C. Seeger; L. Messiaen; R. Versteeg; R. Bernards

    2010-01-01

    Retinoic acid (RA) induces differentiation of neuroblastoma cells in vitro and is used with variable success to treat aggressive forms of this disease. This variability in clinical response to RA is enigmatic, as no mutations in components of the RA signaling cascade have been found. Using a large-s

  3. Dietary fatty acids and immune response to food-borne bacterial infections.

    Science.gov (United States)

    Harrison, Lisa M; Balan, Kannan V; Babu, Uma S

    2013-05-22

    Functional innate and acquired immune responses are required to protect the host from pathogenic bacterial infections. Modulation of host immune functions may have beneficial or deleterious effects on disease outcome. Different types of dietary fatty acids have been shown to have variable effects on bacterial clearance and disease outcome through suppression or activation of immune responses. Therefore, we have chosen to review research across experimental models and food sources on the effects of commonly consumed fatty acids on the most common food-borne pathogens, including Salmonella sp., Campylobacter sp., Shiga toxin-producing Escherichia coli, Shigella sp., Listeria monocytogenes, and Staphylococcus aureus. Altogether, the compilation of literature suggests that no single fatty acid is an answer for protection from all food-borne pathogens, and further research is necessary to determine the best approach to improve disease outcomes.

  4. Light and acid dual-responsive organogel formation based on m-methyl red derivative.

    Science.gov (United States)

    Cao, Xinhua; Gao, Aiping; Lv, Haiting; Wu, Yan; Wang, Xiuxiu; Fan, Yang

    2013-12-07

    A new gelator 1 that included m-methyl red was synthesized and fully characterized. It was found that the organogel of 1 was stable in DMSO even if the organogel was stimulated by acid or light. The organogel was thoroughly characterized using various microscopic techniques including field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), UV-vis and Fourier transform infrared (FTIR) spectra. The organogel exhibited tunable structures and optical properties under different stimulation. The regular nanoring structure was turned into microspheres after the organogel in DMSO was stimulated at 254 nm light or acid. At the same time, the color of molecule 1 in gel state and solution state was all changed after stimulation by light or acid. The hydrogen bonding and π-π stacking were found to be the main driving forces for gel formation. This dual-responsive gel held promise for soft materials application in upscale smart responsive materials.

  5. Molecular mechanisms of Saccharomyces cerevisiae stress adaptation and programmed cell death in response to acetic acid

    Directory of Open Access Journals (Sweden)

    Sergio eGiannattasio

    2013-02-01

    Full Text Available Beyond its classical biotechnological applications such as food and beverage production or as a cell factory, the yeast Saccharomyces cerevisiae is a valuable model organism to study fundamental mechanisms of cell response to stressful environmental changes. Acetic acid is a physiological product of yeast fermentation and it is a well-known food preservative due to its antimicrobial action. Acetic acid has recently been shown to cause yeast cell death and aging. Here we shall focus on the molecular mechanisms of S. cerevisiae stress adaptation and programmed cell death in response to acetic acid. We shall elaborate on the intracellular signaling pathways involved in the cross-talk of pro-survival and pro-death pathways underlying the importance of understanding fundamental aspects of yeast cell homeostasis to improve the performance of a given yeast strain in biotechnological applications.

  6. Targeting amino acid metabolism in cancer growth and anti-tumor immune response

    Institute of Scientific and Technical Information of China (English)

    Elitsa; Ananieva

    2015-01-01

    Recent advances in amino acid metabolism have revealed that targeting amino acid metabolic enzymes in cancer therapy is a promising strategy for the development of novel therapeutic agents. There are currently several drugs in clinical trials that specifically target amino acid metabolic pathways in tumor cells. In the context of the tumor microenvironment,however,tumor cells form metabolic relationships with immune cells,and they oftencompete for common nutrients. Many tumors evolved to escape immune surveillance by taking advantage of their metabolic flexibility and redirecting nutrients for their own advantage. This review outlines the most recent advances in targeting amino acid metabolic pathways in cancer therapy while giving consideration to the impact these pathways may have on the anti-tumor immune response.

  7. Different Responses of Cardiac Cells to Saturated and Unsaturated Fatty Acids

    Directory of Open Access Journals (Sweden)

    I. Khodadadi

    2007-04-01

    Full Text Available Introduction & Objective: The link between dietary fat and coronary heart disease has attracted much attention since the effect of long chain fatty acids (LCFA on gene transcription has been established, which in part, these effects can be explained by the regulation of gene transcription. In this study, the P19CL6 cardiac cell line was targeted for the investigation of (i the effects of long chain fatty acids (LCFA and clofibrate on mRNA levels of specific lipid metabolism related genes, such as heart type fatty acid binding protein (H FABP and peroxisome proliferator activated receptors (PPAR,, in the P19CL6 cell line, and (ii to determine the effects of LCFAs and clofibrate on global transcriptome levels, using cDNA microarray analysis. Materials & Methods: After culturing P19CL6 cells with LCFAs or clofibrate, the total RNA was extracted and expression levels of H-FABP, PPAR, PPAR, and PPAR genes were determined by RT PCR. In addition, microarray analysis was used to compare global transcriptome profiles in P19CL6 cells cultured with different LCFAs or clofibrate.Results: LCFAs significantly increased the abundance of PPAR and PPAR. Moreover, microarray analysis showed the effects of linoleic and  linolenic acids and clofibrate were similar but differed from those of palmitic and oleic acids..Conclusion: These findings show cellular responses to polyunsaturated fatty acids differ from those observed with saturated and monounsaturated fatty acids.

  8. Arabidopsis MAP kinase 4 regulates salicylic acid- and jasmonic acid/ethylene-dependent responses via EDS1 and PAD4.

    Science.gov (United States)

    Brodersen, Peter; Petersen, Morten; Bjørn Nielsen, Henrik; Zhu, Shijiang; Newman, Mari-Anne; Shokat, Kevan M; Rietz, Steffen; Parker, Jane; Mundy, John

    2006-08-01

    Arabidopsis MPK4 has been implicated in plant defense regulation because mpk4 knockout plants exhibit constitutive activation of salicylic acid (SA)-dependent defenses, but fail to induce jasmonic acid (JA) defense marker genes in response to JA. We show here that mpk4 mutants are also defective in defense gene induction in response to ethylene (ET), and that they are more susceptible than wild-type (WT) to Alternaria brassicicola that induces the ET/JA defense pathway(s). Both SA-repressing and ET/JA-(co)activating functions depend on MPK4 kinase activity and involve the defense regulators EDS1 and PAD4, as mutations in these genes suppress de-repression of the SA pathway and suppress the block of the ET/JA pathway in mpk4. EDS1/PAD4 thus affect SA-ET/JA signal antagonism as activators of SA but as repressors of ET/JA defenses, and MPK4 negatively regulates both of these functions. We also show that the MPK4-EDS1/PAD4 branch of ET defense signaling is independent of the ERF1 transcription factor, and use comparative microarray analysis of ctr1, ctr1/mpk4, mpk4 and WT to show that MPK4 is required for induction of a small subset of ET-regulated genes. The regulation of some, but not all, of these genes involves EDS1 and PAD4.

  9. Response of the hammerhead shark olfactory epithelium to amino acid stimuli.

    Science.gov (United States)

    Tricas, Timothy C; Kajiura, Stephen M; Summers, Adam P

    2009-10-01

    Sharks and rays are highly sensitive to chemical stimuli in their natural environment but several hypotheses predict that hammerhead sharks, with their expanded head and enlarged olfactory epithelium, have particularly acute olfactory systems. We used the electro-olfactogram (EOG) technique to compare the relative response of the scalloped hammerhead shark (Sphyrna lewini) olfactory epithelium to 20 proteinogenic amino acids and determine the sensitivity for 6 amino acids. At micromolar concentrations, cysteine evoked the greatest EOG response which was approximately twice as large as that of alanine. The weakest response was obtained for proline followed by aspartic acid and isoleucine. The olfactory epithelium showed adaptation to sequential stimulation, and recovery was related to the inter-stimulus time period. Estimated EOG response thresholds were in the sub-nanomolar range for both alanine (9.2 x 10(-11) M) and cysteine (8.4 x 10(-10) M) and in the micromolar range for proline and serine. These thresholds from 10(-10) to 10(-6) M for the scalloped hammerhead shark are comparable or lower than those reported for other teleost and elasmobranch species. Future work should focus on binary and more complex compounds to test for competition and cross-adaptation for different classes of peripheral receptors, and their responses to molecules found in biologically relevant stimuli.

  10. Effect of Dietary Conjugated Linoleic Acid Supplementation on Early Inflammatory Responses during Cutaneous Wound Healing

    Directory of Open Access Journals (Sweden)

    Na-Young Park

    2010-01-01

    Full Text Available Inflammatory response is considered the most important period that regulates the entire healing process. Conjugated linoleic acid (CLA, a class of linoleic acid positional and geometric isomers, is well known for its antioxidant and anti-inflammatory properties. We hypothesized that dietary CLA supplementation accelerates cutaneous wound healing by regulating antioxidant and anti-inflammatory functions. To investigate wound closure rates and inflammatory responses, we used a full-thickness excisional wound model after 2-week treatments with control, 0.5%, or 1% CLA-supplemented diet. Mice fed dietary CLA supplementation had reduced levels of oxidative stress and inflammatory markers. Moreover, the wound closure rate was improved significantly in mice fed a 1% CLA-supplemented diet during early stage of wound healing (inflammatory stage. We conclude that dietary CLA supplementation enhances the early stage of cutaneous wound healing as a result of modulating oxidative stress and inflammatory responses.

  11. Change in the plasmid copy number in acetic acid bacteria in response to growth phase and acetic acid concentration.

    Science.gov (United States)

    Akasaka, Naoki; Astuti, Wiwik; Ishii, Yuri; Hidese, Ryota; Sakoda, Hisao; Fujiwara, Shinsuke

    2015-06-01

    Plasmids pGE1 (2.5 kb), pGE2 (7.2 kb), and pGE3 (5.5 kb) were isolated from Gluconacetobacter europaeus KGMA0119, and sequence analyses revealed they harbored 3, 8, and 4 genes, respectively. Plasmid copy numbers (PCNs) were determined by real-time quantitative PCR at different stages of bacterial growth. When KGMA0119 was cultured in medium containing 0.4% ethanol and 0.5% acetic acid, PCN of pGE1 increased from 7 copies/genome in the logarithmic phase to a maximum of 12 copies/genome at the beginning of the stationary phase, before decreasing to 4 copies/genome in the late stationary phase. PCNs for pGE2 and pGE3 were maintained at 1-3 copies/genome during all phases of growth. Under a higher concentration of ethanol (3.2%) the PCN for pGE1 was slightly lower in all the growth stages, and those of pGE2 and pGE3 were unchanged. In the presence of 1.0% acetic acid, PCNs were higher for pGE1 (10 copies/genome) and pGE3 (6 copies/genome) during the logarithmic phase. Numbers for pGE2 did not change, indicating that pGE1 and pGE3 increase their PCNs in response to acetic acid. Plasmids pBE2 and pBE3 were constructed by ligating linearized pGE2 and pGE3 into pBR322. Both plasmids were replicable in Escherichia coli, Acetobacter pasteurianus and G. europaeus, highlighting their suitability as vectors for acetic acid bacteria.

  12. Lipid binding protein response to a bile acid library: a combined NMR and statistical approach.

    Science.gov (United States)

    Tomaselli, Simona; Pagano, Katiuscia; Boulton, Stephen; Zanzoni, Serena; Melacini, Giuseppe; Molinari, Henriette; Ragona, Laura

    2015-11-01

    Primary bile acids, differing in hydroxylation pattern, are synthesized from cholesterol in the liver and, once formed, can undergo extensive enzyme-catalysed glycine/taurine conjugation, giving rise to a complex mixture, the bile acid pool. Composition and concentration of the bile acid pool may be altered in diseases, posing a general question on the response of the carrier (bile acid binding protein) to the binding of ligands with different hydrophobic and steric profiles. A collection of NMR experiments (H/D exchange, HET-SOFAST, ePHOGSY NOESY/ROESY and (15) N relaxation measurements) was thus performed on apo and five different holo proteins, to monitor the binding pocket accessibility and dynamics. The ensemble of obtained data could be rationalized by a statistical approach, based on chemical shift covariance analysis, in terms of residue-specific correlations and collective protein response to ligand binding. The results indicate that the same residues are influenced by diverse chemical stresses: ligand binding always induces silencing of motions at the protein portal with a concomitant conformational rearrangement of a network of residues, located at the protein anti-portal region. This network of amino acids, which do not belong to the binding site, forms a contiguous surface, sensing the presence of the bound lipids, with a signalling role in switching protein-membrane interactions on and off.

  13. Physiological responses of root-less epiphytic plants to acid rain.

    Science.gov (United States)

    Kováčik, Jozef; Klejdus, Bořivoj; Bačkor, Martin; Stork, František; Hedbavny, Josef

    2011-03-01

    Selected physiological responses of Tillandsia albida (Bromeliaceae) and two lichens (Hypogymnia physodes and Xanthoria parietina) exposed to simulated acid rain (AR) over 3 months were studied. Pigments were depressed in all species being affected the most in Tillandsia. Amounts of hydrogen peroxide and superoxide were elevated and soluble proteins decreased only in AR-exposed Hypogymnia. Free amino acids were slightly affected among species and only glutamate sharply decreased in AR-exposed Xanthoria. Slight increase in soluble phenols but decrease in flavonoids in almost all species suggests that the latter are not essential for tolerance to AR. Almost all phenolic acids in Tillandsia leaves decreased in response to AR and activities of selected enzymes (phenylalanine ammonia-lyase, polyphenol oxidase, ascorbate- and guaiacol-peroxidase) were enhanced by AR. In lichens, considerable increase in metabolites (physodalic acid, atranorin and parietin) in response to AR was found but amount of ergosterol was unchanged. Macronutrients (K, Ca, Mg) decreased more pronouncedly in comparison with micronutrients in all species. Xanthoria showed higher tolerance in comparison with Hypogymnia, suggesting that could be useful for long-term biomonitoring.

  14. Potentiation of vasoconstrictor response and inhibition of endothelium-dependent vasorelaxation by gallic acid in rat aorta.

    Science.gov (United States)

    Sanae, Fujiko; Miyaichi, Yukinori; Hayashi, Hisao

    2002-08-01

    In the isolated rat thoracic aorta, gallic acid potentiated the vasoconstrictor response to phenylephrine. The potentiation produced by gallic acid was absent in endothelium-denuded arteries. The potentiation was abolished by N(G)-nitro-L-arginine methyl ester, an inhibitor of nitric oxide synthesis, and slightly attenuated by an addition of L-arginine, while indomethacin or BQ610 had no effect. The potentiation of response to phenylephrine was not found for structural modifications of gallic acid, except for caffeic acid. Gallic acid also inhibited vasorelaxation induced by acetylcholine, sodium nitroprusside or prostacyclin, especially that by acetylcholine. The effect on vasorelaxation induced by acetylcholine was decreased by esterification of the carboxy group of gallic acid, and in the absence or by the methylation of the o-dihydroxy group. Caffeic acid inhibited the vasorelaxation, though the effect was smaller than that of gallic acid. These findings indicate that gallic acid produces a potentiation of contractile response and inhibition of vasorelaxant responses, probably through inactivation of nitric oxide (NO), in which endothelially produced NO is principally involved, and that the modification of functional groups of the gallic acid molecule abolishes the potentiation of contractile response and attenuates the inhibition of vasorelaxant responses.

  15. Effects of diets high in unsaturated Fatty acids on socially induced stress responses in Guinea pigs.

    Science.gov (United States)

    Nemeth, Matthias; Millesi, Eva; Wagner, Karl-Heinz; Wallner, Bernard

    2014-01-01

    Unsaturated fatty acids (UFAs), such as omega-3 and omega-6 poly- and omega-9 monounsaturated fatty acids are important nutrients and major components of neuronal cell membranes. They play a major role in modulating brain functions and physiology and may therefore diminish behavioral and physiological stress reactions in corroboration with decreased cortisol concentrations. Functionally, cortisol itself can modulate several behaviors and also the fatty acid metabolism in the long term. But only little is known about the behavioral and physiological influences of dietary UFAs in a social group, where individuals are regularly exposed to stressful situations. Therefore, the aim of this study was to determine the effects of dietary UFAs on saliva cortisol concentrations and behavioral responses in socially confronted guinea pigs. Three groups of animals were additionally supplemented with 500 mg chia seeds (high in omega-3), walnuts (high in omega-6), or peanuts (high in omega-9) per kg bodyweight each day and compared to a control group. During social confrontation saliva cortisol concentrations significantly increased in all groups, which was accompanied by a loss in bodyweight. However, cortisol levels remained lower in the chia and walnut groups compared to controls. Additionally, the walnut group displayed significantly increased locomotion, while no differences between groups were detected in socio-positive, sexual, or aggressive behaviors. Total plasma omega-3, omega-6, and omega-9 fatty acids were significantly increased in the corresponding groups, due to the dietary supplementations. However, a significant decrease in plasma omega-3 and an increase in plasma n-6 fatty acids were detected in the chia group when comparing the measurements before and after social confrontation. We conclude that both omega-3 and omega-6 polyunsaturated fatty acids can diminish behavioral and physiological stress responses to the social environment, enabling individuals to cope

  16. Effects of diets high in unsaturated Fatty acids on socially induced stress responses in Guinea pigs.

    Directory of Open Access Journals (Sweden)

    Matthias Nemeth

    Full Text Available Unsaturated fatty acids (UFAs, such as omega-3 and omega-6 poly- and omega-9 monounsaturated fatty acids are important nutrients and major components of neuronal cell membranes. They play a major role in modulating brain functions and physiology and may therefore diminish behavioral and physiological stress reactions in corroboration with decreased cortisol concentrations. Functionally, cortisol itself can modulate several behaviors and also the fatty acid metabolism in the long term. But only little is known about the behavioral and physiological influences of dietary UFAs in a social group, where individuals are regularly exposed to stressful situations. Therefore, the aim of this study was to determine the effects of dietary UFAs on saliva cortisol concentrations and behavioral responses in socially confronted guinea pigs. Three groups of animals were additionally supplemented with 500 mg chia seeds (high in omega-3, walnuts (high in omega-6, or peanuts (high in omega-9 per kg bodyweight each day and compared to a control group. During social confrontation saliva cortisol concentrations significantly increased in all groups, which was accompanied by a loss in bodyweight. However, cortisol levels remained lower in the chia and walnut groups compared to controls. Additionally, the walnut group displayed significantly increased locomotion, while no differences between groups were detected in socio-positive, sexual, or aggressive behaviors. Total plasma omega-3, omega-6, and omega-9 fatty acids were significantly increased in the corresponding groups, due to the dietary supplementations. However, a significant decrease in plasma omega-3 and an increase in plasma n-6 fatty acids were detected in the chia group when comparing the measurements before and after social confrontation. We conclude that both omega-3 and omega-6 polyunsaturated fatty acids can diminish behavioral and physiological stress responses to the social environment, enabling

  17. Antioxidant response of soybean seedlings to joint stress of lanthanum and acid rain.

    Science.gov (United States)

    Liang, Chanjuan; Wang, Weimin

    2013-11-01

    Excess of rare earth elements in soil can be a serious environmental stress on plants, in particular when acid rain coexists. To understand how such a stress affects plants, we studied antioxidant response of soybean leaves and roots exposed to lanthanum (0.06, 0.18, and 0.85 mmol L(-1)) under acid rain conditions (pH 4.5 and 3.0). We found that low concentration of La3+ (0.06 mmol L(-1)) did not affect the activity of antioxidant enzymes (catalase and peroxidase) whereas high concentration of La3+ (≥0.18 mmol L(-1)) did. Compared to treatment with acid rain (pH 4.5 and pH 3.0) or La3+ alone, joint stress of La3+ and acid rain affected more severely the activity of catalase and peroxidase, and induced more H2O2 accumulation and lipid peroxidation. When treated with high level of La3+ (0.85 mmol L(-1)) alone or with acid rain (pH 4.5 and 3.0), roots were more affected than leaves regarding the inhibition of antioxidant enzymes, physiological function, and growth. The severity of oxidative damage and inhibition of growth caused by the joint stress associated positively with La3+ concentration and soil acidity. These results will help us understand plant response to joint stress, recognize the adverse environmental impact of rare earth elements in acidic soil, and develop measures to eliminate damage caused by such joint stress.

  18. Comparative Transcriptomics Reveals Discrete Survival Responses of S. aureus and S. epidermidis to Sapienic Acid

    Science.gov (United States)

    Moran, Josephine C.; Alorabi, Jamal A.; Horsburgh, Malcolm J.

    2017-01-01

    Staphylococcal colonization of human skin is ubiquitous, with particular species more frequent at different body sites. Whereas Staphylococcus epidermidis can be isolated from the skin of every individual tested, Staphylococcus aureus is isolated from arginine deiminase, the oxygen-responsive NreABC nitrogen regulation system and the nitrate and nitrite reduction pathways. The role of S. aureus ACME and chromosomal arginine deiminase pathways in sapienic acid resistance was determined through mutational studies. We speculate that ammonia production could contribute to sapienic acid resistance in staphylococci. PMID:28179897

  19. Role of p53 in the cellular response following oleic acid accumulation in Chang liver cells.

    Science.gov (United States)

    Park, Eun-Jung; Lee, Ah Young; Chang, Seung-Hee; Yu, Kyeong-Nam; Kim, Jae-Ho; Cho, Myung-Haing

    2014-01-03

    Abnormal accumulation of fatty acids triggers the harmful cellular response called lipotoxicity. In this study, we investigated the cellular response following accumulation of oleic acid (OA), a monounsaturated fatty acid, in human Chang liver cells. OA droplets were distributed freely in the cytoplasm and/or degraded within lysosomes. OA exposure increased ATP production and concomitantly dilated mitochondria. At 24h after OA exposure, cell viability decreased slightly and was coupled with a reduction in mitochondrial Ca(2+) concentration, the alteration in cell viability was also associated with the generation of reactive oxygen species and changes in the cell cycle. Moreover, OA treatment increased the expression of autophagy- and apoptotic cell death-related proteins in a dose-dependent manner. Furthermore, we investigated the role of p53, a tumor suppressor protein, in the cellular response elicited by OA accumulation. OA-induced changes in cell viability and ATP production were rescued to control levels when cells were pretreated with pifithrin-alpha (PTA), a p53 inhibitor. By contrast, the expressions of LC3-II and perilipin, proteins required for lipophagy, were down-regulated by PTA pretreatment. Taken together, our results suggest that p53 plays a key role in the cellular response elicited by OA accumulation in Chang liver cells.

  20. Global mapping of protein phosphorylation events identifies novel signalling hubs mediating fatty acid starvation responses in Saccharomyces cerevisiae

    DEFF Research Database (Denmark)

    Pultz, Dennis; Bennetzen, Martin; Rødkær, Steven Vestergaard;

    2011-01-01

    in a temporal manner in response to inhibition of fatty acid synthesis by cerulenin. By in silico analysis of these phosphorylation events, we have identified the major downstream regulated processes and signalling networks mediating the cellular response to fatty acid starvation. The analysis further...

  1. In Vitro Cytotoxicity and Adaptive Stress Responses to Selected Haloacetic Acid and Halobenzoquinone Water Disinfection Byproducts.

    Science.gov (United States)

    Procházka, Erik; Escher, Beate I; Plewa, Michael J; Leusch, Frederic D L

    2015-10-19

    The process of disinfecting drinking water inadvertently leads to the formation of numerous disinfection byproducts (DBPs). Some of these are mutagenic, genotoxic, teratogenic, and cytotoxic, as well as potentially carcinogenic both in vivo and in vitro. We investigated the in vitro biological activity of five DBPs: three monohaloacetic acids (monoHAAs) [chloroacetic acid (CAA), bromoacetic acid (BAA), and iodoacetic acid (IAA)] and two novel halobenzoquinones (HBQs) [2,6-dichloro-p-benzoquinone (DCBQ) and 2,6-dibromo-p-benzoquinone]. We focused particularly on cytotoxicity and induction of two adaptive stress response pathways: the oxidative stress responsive Nrf2/ARE and DNA-damage responsive p53 pathways. All five DBPs were cytotoxic to the Caco-2 cell line after a 4 h exposure, and all DBPs induced both of the adaptive stress response pathways, Nrf2/ARE and p53, in the micromolar range, as measured by two β-lactamase-based reporter gene assays. The decreasing order of potency for all three endpoints for the five DBPs was IAA ∼ BAA > DCBQ ∼ DBBQ > CAA. Induction of oxidative stress was previously proposed to be the molecular initiating event (MIE) for both classes of DBPs. However, comparing the levels of activation of the two pathways uncovered that the Nrf2/ARE pathway was the more sensitive endpoint for HAAs, whereas the p53 pathway was more sensitive in the case of HBQs. Therefore, the DNA damage-responsive p53 pathway may be an important piece of information to fill in a gap in the adverse outcome pathway framework for the assessment of HBQs. Finally, we cautiously compared the potential risk of the two novel HBQs using a benchmarking approach to that of the well-studied CAA, which suggested that their relative risk may be lower than that of BAA and IAA.

  2. Oviposition response ofLobesia botrana females to long-chain free fatty acids and esters from its eggs.

    Science.gov (United States)

    Gabel, B; Thiéry, D

    1996-01-01

    Avoidance of occupied ovisposition sites supposes that females perceive information related to their own progency. Fatty acids identified from egg extracts have been reevaluated using a different extraction method, and we have investigated the dose-dependent oviposition response of European grape vine moths (Lobesia botrana) to myristic acid, palmitic acid, palmitoleic acid, stearic acid, oleic acid, linoleic acid, methyl palmitate, methyl oleate, and ethyl palmitate; all except ethyl palmitate have been identified from eggs ofL. botrana. A methylene dichloride extract of eggs fromL. botrana revealed the presence of saturated free fatty acids (myristic, palmitic, and stearic) and unsaturated acids (palmitoleic, oleic, linoleic, and linolenic) in amounts ranging from 3.9 ng/egg equivalent for myristic acid to 30 ng/egg equivalent for palmitic and oleic acids. The extract also contained traces of methyl palmitate and methyl stearate. The greatest avoidance indexes were observed in response to palmitic, palmitoleic, and oleic acids. All the other compounds tested caused weaker responses. A reduction in the number of eggs laid was observed when moths were exposed to each of the esters applied at 0.3 µg per application spot. Reduction in eggs laid was also observed at a 10-fold higher dose of oleic acid. The present results confirm that general and simple molecules can be involved in the regulation of oviposition site selection and that they may participate in chemical marking of the eggs.

  3. Arginine-responsive terbium luminescent hybrid sensors triggered by two crown ether carboxylic acids

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Lasheng [Key Laboratory of Theoretical Chemistry of Environment, Ministry of Education, School of Chemistry and Environment, South China Normal University, Guangzhou 510006 (China); School of Chemistry and Environment, South China Normal University, Guangzhou 510006 (China); Tang, Ke; Ding, Xiaoping [School of Chemistry and Environment, South China Normal University, Guangzhou 510006 (China); Wang, Qianming, E-mail: qmwang@scnu.edu.cn [Key Laboratory of Theoretical Chemistry of Environment, Ministry of Education, School of Chemistry and Environment, South China Normal University, Guangzhou 510006 (China); School of Chemistry and Environment, South China Normal University, Guangzhou 510006 (China); Zhou, Zhan; Xiao, Rui [School of Chemistry and Environment, South China Normal University, Guangzhou 510006 (China)

    2013-12-01

    Crown ether carboxylic acids constitute main building blocks for the synthesis of terbium containing covalent cross-linked luminescent materials. Both the complexes and the hybrid nanomaterials could exhibit remarkable green emissions in pure water. More importantly, they were found to have a profound effect on the luminescence responses to arginine compared with glutamic acid, histidine, tryptophan, threonine, tyrosine and phenylalanine in aqueous environment. The present study provided the possibility of using a host–guest mechanism as a way of signal transduction based on lanthanide supramolecular hybrid materials. - Highlights: • Crown ether carboxylic acids were found to sensitize terbium ions among a group of ethers. • The complexes and silica hybrid materials were both prepared and characterized. • They could exhibit remarkable green emissions in pure water.

  4. Modelling and Statistical Optimization of Dilute Acid Hydrolysis of Corn Stover Using Response Surface Methodology

    Directory of Open Access Journals (Sweden)

    Andrew Nosakhare Amenaghawon

    2014-07-01

    Full Text Available Response surface methodology (RSM was employed for the analysis of the simultaneous effect of acid concentration, pretreatment time and temperature on the total reducing sugar concentration obtained during acid hydrolysis of corn stover. A three-variable, three-level Box-Behnken design (BBD was used to develop a statistical model for the optimization of the process variables. The optimal hydrolysis conditions that resulted in the maximum total reducing sugar concentration were acid concentration; 1.72 % (w/w, temperature; 169.260C and pretreatment time; 48.73 minutes. Under these conditions, the total reducing sugar concentration was obtained to be 23.41g/L. Validation of the model indicated no difference between predicted and observed values.

  5. N-3 polyunsaturated fatty acids do not affect the cytokine response to strenuous exercise

    DEFF Research Database (Denmark)

    Toft, A.D.; Thorn, Mette; Ostrowski, Kenneth

    2000-01-01

    (PUFA), for 6 wk or to receive no supplementation (n = 10) before participating in The Copenhagen Marathon 1998. Blood samples were collected before the race, immediately after, and 1.5 and 3 h postexercise. The fatty acid composition in blood mononuclear cells (BMNC) differed between the fish oil......The aim of the present study was to investigate whether fish oil supplementation was able to modulate the acute-phase response to strenuous exercise. Twenty male runners were randomized to receive supplementation (n = 10) with 6.0 g fish oil daily, containing 3.6 g n-3 polyunsaturated fatty acids......-supplemented and the control group, showing incorporation of n-3 PUFA and less arachidonic acid in BMNC in the supplemented group. The plasma levels of tumor necrosis factor-alpha, interleukin-6, and transforming growth factor-beta(1) peaked immediately after the run, the increase being 3-, 92-, and 1.1-fold, respectively...

  6. Marsh plant response to metals: Exudation of aliphatic low molecular weight organic acids (ALMWOAs)

    Science.gov (United States)

    Rocha, A. Cristina S.; Almeida, C. Marisa R.; Basto, M. Clara P.; Vasconcelos, M. Teresa S. D.

    2016-03-01

    Metal exposure is known to induce the production and secretion of substances, such as aliphatic low molecular weight organic acids (ALMWOAs), into the rhizosphere by plant roots. Knowledge on this matter is extensive for soil plants but still considerably scarce regarding marsh plants roots adapted to high salinity media. Phragmites australis and Halimione portulacoides, two marsh plants commonly distributed in European estuarine salt marshes, were used to assess the response of roots of both species, in terms of ALMWOAs exudation, to Cu, Ni and Cd exposure (isolated and in mixture since in natural environment, they are exposed to mixture of metals). As previous studies were carried out in unrealistic and synthetic media, here a more natural medium was selected. Therefore, in vitro experiments were carried out, with specimens of both marsh plants, and in freshwater contaminated with two different Cu, Ni and Cd concentrations (individual metal and in mixture). Both marsh plants were capable of liberating ALMWOAs into the surrounding medium. Oxalic, citric and maleic acids were found in P. australis root exudate solutions and oxalic and maleic acids in H. portulacoides root exudate solutions. ALMWOA liberation by both plants was plant species and metal-dependent. For instance, Cu affected the exudation of oxalic acid by H. portulacoides and of oxalic and citric acids by P. australis roots. In contrast, Ni and Cd did not stimulate any specific response. Regarding the combination of all metals, H. portulacoides showed a similar response to that observed for Cu individually. However, in the P. australis case, at high metal concentration mixture, a synergetic effect led to the increase of oxalic acid levels in root exudate solution and to a decrease of citric acid liberation. A correlation between ALMWOAs exudation and metal accumulation could not be established. P. australis and H. portulacoides are considered suitable metal phytoremediators of estuarine impacted areas

  7. The acid adaptive tolerance response in Campylobacter jejuni induces a global response, as suggested by proteomics and microarrays.

    Science.gov (United States)

    Varsaki, Athanasia; Murphy, Caroline; Barczynska, Alicja; Jordan, Kieran; Carroll, Cyril

    2015-11-01

    Campylobacter jejuni CI 120 is a natural isolate obtained during poultry processing and has the ability to induce an acid tolerance response (ATR) to acid + aerobic conditions in early stationary phase. Other strains tested they did not induce an ATR or they induced it in exponential phase. Campylobacter spp. do not contain the genes that encode the global stationary phase stress response mechanism. Therefore, the aim of this study was to identify genes that are involved in the C. jejuni CI 120 early stationary phase ATR, as it seems to be expressing a novel mechanism of stress tolerance. Two-dimensional gel electrophoresis was used to examine the expression profile of cytosolic proteins during the C. jejuni CI 120 adaptation to acid + aerobic stress and microarrays to determine the genes that participate in the ATR. The results indicate induction of a global response that activated a number of stress responses, including several genes encoding surface components and genes involved with iron uptake. The findings of this study provide new insights into stress tolerance of C. jejuni, contribute to a better knowledge of the physiology of this bacterium and highlight the diversity among different strains.

  8. PTH1 receptor is involved in mediating cellular response to long-chain polyunsaturated fatty acids.

    Directory of Open Access Journals (Sweden)

    Jose Candelario

    Full Text Available The molecular pathways by which long chain polyunsaturated fatty acids (LCPUFA influence skeletal health remain elusive. Both LCPUFA and parathyroid hormone type 1 receptor (PTH1R are known to be involved in bone metabolism while any direct link between the two is yet to be established. Here we report that LCPUFA are capable of direct, PTH1R dependent activation of extracellular ligand-regulated kinases (ERK. From a wide range of fatty acids studied, varying in chain length, saturation, and position of double bonds, eicosapentaenoic (EPA and docosahexaenoic fatty acids (DHA caused the highest ERK phosphorylation. Moreover, EPA potentiated the effect of parathyroid hormone (PTH(1-34 in a superagonistic manner. EPA or DHA dependent ERK phosphorylation was inhibited by the PTH1R antagonist and by knockdown of PTH1R. Inhibition of PTH1R downstream signaling molecules, protein kinases A (PKA and C (PKC, reduced EPA and DHA dependent ERK phosphorylation indicating that fatty acids predominantly activate G-protein pathway and not the β-arrestin pathway. Using picosecond time-resolved fluorescence microscopy and a genetically engineered PTH1R sensor (PTH-CC, we detected conformational responses to EPA similar to those caused by PTH(1-34. PTH1R antagonist blocked the EPA induced conformational response of the PTH-CC. Competitive binding studies using fluorescence anisotropy technique showed that EPA and DHA competitively bind to and alter the affinity of PTH1 receptor to PTH(1-34 leading to a superagonistic response. Finally, we showed that EPA stimulates protein kinase B (Akt phosphorylation in a PTH1R-dependent manner and affects the osteoblast survival pathway, by inhibiting glucocorticoid-induced cell death. Our findings demonstrate for the first time that LCPUFAs, EPA and DHA, can activate PTH1R receptor at nanomolar concentrations and consequently provide a putative molecular mechanism for the action of fatty acids in bone.

  9. Response of soil respiration to acid rain in forests of different maturity in southern China.

    Directory of Open Access Journals (Sweden)

    Guohua Liang

    Full Text Available The response of soil respiration to acid rain in forests, especially in forests of different maturity, is poorly understood in southern China despite the fact that acid rain has become a serious environmental threat in this region in recent years. Here, we investigated this issue in three subtropical forests of different maturity [i.e. a young pine forest (PF, a transitional mixed conifer and broadleaf forest (MF and an old-growth broadleaved forest (BF] in southern China. Soil respiration was measured over two years under four simulated acid rain (SAR treatments (CK, the local lake water, pH 4.5; T1, water pH 4.0; T2, water pH 3.5; and T3, water pH 3.0. Results indicated that SAR did not significantly affect soil respiration in the PF, whereas it significantly reduced soil respiration in the MF and the BF. The depressed effects on both forests occurred mostly in the warm-wet seasons and were correlated with a decrease in soil microbial activity and in fine root biomass caused by soil acidification under SAR. The sensitivity of the response of soil respiration to SAR showed an increasing trend with the progressive maturity of the three forests, which may result from their differences in acid buffering ability in soil and in litter layer. These results indicated that the depressed effect of acid rain on soil respiration in southern China may be more pronounced in the future in light of the projected change in forest maturity. However, due to the nature of this field study with chronosequence design and the related pseudoreplication for forest types, this inference should be read with caution. Further studies are needed to draw rigorous conclusions regarding the response differences among forests of different maturity using replicated forest types.

  10. Response of soil respiration to acid rain in forests of different maturity in southern China.

    Science.gov (United States)

    Liang, Guohua; Liu, Xingzhao; Chen, Xiaomei; Qiu, Qingyan; Zhang, Deqiang; Chu, Guowei; Liu, Juxiu; Liu, Shizhong; Zhou, Guoyi

    2013-01-01

    The response of soil respiration to acid rain in forests, especially in forests of different maturity, is poorly understood in southern China despite the fact that acid rain has become a serious environmental threat in this region in recent years. Here, we investigated this issue in three subtropical forests of different maturity [i.e. a young pine forest (PF), a transitional mixed conifer and broadleaf forest (MF) and an old-growth broadleaved forest (BF)] in southern China. Soil respiration was measured over two years under four simulated acid rain (SAR) treatments (CK, the local lake water, pH 4.5; T1, water pH 4.0; T2, water pH 3.5; and T3, water pH 3.0). Results indicated that SAR did not significantly affect soil respiration in the PF, whereas it significantly reduced soil respiration in the MF and the BF. The depressed effects on both forests occurred mostly in the warm-wet seasons and were correlated with a decrease in soil microbial activity and in fine root biomass caused by soil acidification under SAR. The sensitivity of the response of soil respiration to SAR showed an increasing trend with the progressive maturity of the three forests, which may result from their differences in acid buffering ability in soil and in litter layer. These results indicated that the depressed effect of acid rain on soil respiration in southern China may be more pronounced in the future in light of the projected change in forest maturity. However, due to the nature of this field study with chronosequence design and the related pseudoreplication for forest types, this inference should be read with caution. Further studies are needed to draw rigorous conclusions regarding the response differences among forests of different maturity using replicated forest types.

  11. Transcriptome analysis of Rhizopus oryzae in response to xylose during fumaric acid production.

    Science.gov (United States)

    Xu, Qing; Liu, Ying; Li, Shuang; Jiang, Ling; Huang, He; Wen, Jianping

    2016-08-01

    Xylose is one of the most abundant lignocellulosic components, but it cannot be used by R. oryzae for fumaric acid production. Here, we applied high-throughput RNA sequencing to generate two transcriptional maps of R. oryzae following fermentation in glucose or xylose. The differential expression analysis showed that, genes involved in amino acid metabolism, fatty acid metabolism, and gluconeogenesis, were up-regulated in response to xylose. Moreover, we discovered the potential presence of oxidative stress in R. oryzae during xylose fermentation. To adapt to this unfavorable condition, R. oryzae displayed reduced growth and induce of a number of antioxidant enzymes, including genes involved in glutathione, trehalose synthesis, and the proteasomal pathway. These responses might divert the flow of carbon required for the accumulation of fumaric acid. Furthermore, using high-throughput RNA sequencing, we identified a large number of novel transcripts and a substantial number of genes that underwent alternative splicing. Our analysis provides remarkable insight into the mechanisms underlying xylose fermentation by R. oryzae. These results may reveal potential target genes or strategies to improve xylose fermentation.

  12. Altered growth response to exogenous auxin and gibberellic acid by gravistimulation in pulvini of Avena sativa

    Science.gov (United States)

    Brock, T. G.; Kaufman, P. B.

    1988-01-01

    Pulvini of excised segments from oats (Avena sativa L. cv Victory) were treated unilaterally with indoleacetic acid (IAA) or gibberellic acid (GA3) with or without gravistimulation to assess the effect of gravistimulation on hormone action. Optimum pulvinus elongation growth (millimeters) and segment curvature (degrees) over 24 hours were prod