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Sample records for jasmonic acid signaling

  1. How salicylic acid takes transcriptional control over jasmonic acid signaling

    Caarls, Lotte|info:eu-repo/dai/nl/371746213; Pieterse, Corné M J|info:eu-repo/dai/nl/113115113; van Wees, Saskia C M|info:eu-repo/dai/nl/185445373

    2015-01-01

    Transcriptional regulation is a central process in plant immunity. The induction or repression of defense genes is orchestrated by signaling networks that are directed by plant hormones of which salicylic acid (SA) and jasmonic acid (JA) are the major players. Extensive cross-communication between

  2. How salicylic acid takes transcriptional control over jasmonic acid signaling

    Lotte eCaarls

    2015-03-01

    Full Text Available Transcriptional regulation is a central process in plant immunity. The induction or repression of defense genes is orchestrated by signaling networks that are directed by plant hormones of which salicylic acid (SA and jasmonic acid (JA are the major players. Extensive cross-communication between the hormone signaling pathways allows for fine tuning of transcriptional programs, determining resistance to invaders and trade-offs with plant development. Here, we give an overview of how SA can control transcriptional reprogramming of JA-induced genes in Arabidopsis thaliana. SA can influence activity and/or localization of transcriptional regulators by post-translational modifications of transcription factors and co-regulators. SA-induced redox changes, mediated by thioredoxins and glutaredoxins, modify transcriptional regulators that are involved in suppression of JA-dependent genes, such as NPR1 and TGA transcription factors, which affects their localization or DNA binding activity. Furthermore, SA can mediate sequestering of JA-responsive transcription factors away from their target genes by stalling them in the cytosol or in complexes with repressor proteins in the nucleus. SA also affects JA-induced transcription by inducing degradation of transcription factors with an activating role in JA signaling, as was shown for the ERF transcription factor ORA59. Additionally, SA can induce negative regulators, among which WRKY transcription factors, that can directly or indirectly inhibit JA-responsive gene expression. Finally, at the DNA level, modification of histones by SA-dependent factors can result in repression of JA-responsive genes. These diverse and complex regulatory mechanisms affect important signaling hubs in the integration of hormone signaling networks. Some pathogens have evolved effectors that highjack hormone crosstalk mechanisms for their own good, which are described in this review as well.

  3. Jasmonic acid signaling modulates ozone-induced hypersensitive cell death.

    Rao, M V; Lee, H; Creelman, R A; Mullet, J E; Davis, K R

    2000-09-01

    Recent studies suggest that cross-talk between salicylic acid (SA)-, jasmonic acid (JA)-, and ethylene-dependent signaling pathways regulates plant responses to both abiotic and biotic stress factors. Earlier studies demonstrated that ozone (O(3)) exposure activates a hypersensitive response (HR)-like cell death pathway in the Arabidopsis ecotype Cvi-0. We now have confirmed the role of SA and JA signaling in influencing O(3)-induced cell death. Expression of salicylate hydroxylase (NahG) in Cvi-0 reduced O(3)-induced cell death. Methyl jasmonate (Me-JA) pretreatment of Cvi-0 decreased O(3)-induced H(2)O(2) content and SA concentrations and completely abolished O(3)-induced cell death. Cvi-0 synthesized as much JA as did Col-0 in response to O(3) exposure but exhibited much less sensitivity to exogenous Me-JA. Analyses of the responses to O(3) of the JA-signaling mutants jar1 and fad3/7/8 also demonstrated an antagonistic relationship between JA- and SA-signaling pathways in controlling the magnitude of O(3)-induced HR-like cell death.

  4. Ethylene signaling renders the jasmonate response of Arabidopsis insensitive to future suppression by salicylic acid

    Leon Reyes, H.A.; Du, Y.; Koornneef, A.; Proietti, S.; Körbes, A.P.; Memelink, J.; Pieterse, C.M.J.; Ritsema, T.

    2010-01-01

    Cross-talk between jasmonate (JA), ethylene (ET), and Salicylic acid (SA) signaling is thought to operate as a mechanism to fine-tune induced defenses that are activated in response to multiple attackers. Here, 43 Arabidopsis genotypes impaired in hormone signaling or defense-related processes were

  5. Feeding by whiteflies suppresses downstream jasmonic acid signaling by eliciting salicylic acid signaling.

    Zhang, Peng-Jun; Li, Wei-Di; Huang, Fang; Zhang, Jin-Ming; Xu, Fang-Cheng; Lu, Yao-Bin

    2013-05-01

    Phloem-feeding whiteflies in the species complex Bemisia tabaci cause extensive crop damage worldwide. One of the reasons for their "success" is their ability to suppress the effectual jasmonic acid (JA) defenses of the host plant. However, little is understood about the mechanisms underlying whitefly suppression of JA-regulated defenses. Here, we showed that the expression of salicylic acid (SA)-responsive genes (EDS1 and PR1) in Arabidopsis thaliana was significantly enhanced during feeding by whitefly nymphs. Whereas upstream JA-responsive genes (LOX2 and OPR3) also were induced, the downstream JA-responsive gene (VSP1) was repressed, i.e., whiteflies only suppressed downstream JA signaling. Gene-expression analyses with various Arabidopsis mutants, including NahG, npr-1, ein2-1, and dde2-2, revealed that SA signaling plays a key role in the suppression of downstream JA defenses by whitefly feeding. Assays confirmed that SA activation enhanced whitefly performance by suppressing downstream JA defenses.

  6. Weights in the balance: jasmonic acid and salicylic acid signaling in root-biotroph interactions.

    Gutjahr, Caroline; Paszkowski, Uta

    2009-07-01

    Work on the interaction of aerial plant parts with pathogens has identified the signaling molecules jasmonic acid (JA) and salicylic acid (SA) as important players in induced defense of the plant against invading organisms. Much less is known about the role of JA and SA signaling in root infection. Recent progress has been made in research on plant interactions with biotrophic mutualists and parasites that exclusively associate with roots, namely arbuscular mycorrhizal and rhizobial symbioses on one hand and nematode and parasitic plant interactions on the other hand. Here, we review these recent advances relating JA and SA signaling to specific stages of root colonization and discuss how both signaling molecules contribute to a balance between compatibility and defense in mutualistic as well as parasitic biotroph-root interactions.

  7. Ethylene signaling renders the jasmonate response of Arabidopsis insensitive to future suppression by salicylic acid

    Leon Reyes, H.A.; Du, Y.; Koornneef, A.; Proietti, S.; Körbes, A.P.; Memelink, J.; Pieterse, C.M.J.; Ritsema, T.

    2010-01-01

    Cross-talk between jasmonate (JA), ethylene (ET), and Salicylic acid (SA) signaling is thought to operate as a mechanism to fine-tune induced defenses that are activated in response to multiple attackers. Here, 43 Arabidopsis genotypes impaired in hormone signaling or defense-related processes were screened for their ability to express SA-mediated suppression of JA-responsive gene expression. Mutant cev1, which displays constitutive expression of JA and ET responses, appeared to be insensitiv...

  8. AtWRKY22 promotes susceptibility to aphids and modulates salicylic acid and jasmonic acid signalling.

    Kloth, Karen J; Wiegers, Gerrie L; Busscher-Lange, Jacqueline; van Haarst, Jan C; Kruijer, Willem; Bouwmeester, Harro J; Dicke, Marcel; Jongsma, Maarten A

    2016-05-01

    Aphids induce many transcriptional perturbations in their host plants, but the signalling cascades responsible and the effects on plant resistance are largely unknown. Through a genome-wide association (GWA) mapping study in Arabidopsis thaliana, we identified WRKY22 as a candidate gene associated with feeding behaviour of the green peach aphid, Myzus persicae The transcription factor WRKY22 is known to be involved in pathogen-triggered immunity, and WRKY22 gene expression has been shown to be induced by aphids. Assessment of aphid population development and feeding behaviour on knockout mutants and overexpression lines showed that WRKY22 increases susceptibility to M. persicae via a mesophyll-located mechanism. mRNA sequencing analysis of aphid-infested wrky22 knockout plants revealed the up-regulation of genes involved in salicylic acid (SA) signalling and down-regulation of genes involved in plant growth and cell-wall loosening. In addition, mechanostimulation of knockout plants by clip cages up-regulated jasmonic acid (JA)-responsive genes, resulting in substantial negative JA-SA crosstalk. Based on this and previous studies, WRKY22 is considered to modulate the interplay between the SA and JA pathways in response to a wide range of biotic and abiotic stimuli. Its induction by aphids and its role in suppressing SA and JA signalling make WRKY22 a potential target for aphids to manipulate host plant defences. © The Author 2016. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  9. Simultaneous Determination of Salicylic Acid, Jasmonic Acid, Methyl Salicylate, and Methyl Jasmonate from Ulmus pumila Leaves by GC-MS

    Zhi-hong Huang

    2015-01-01

    Full Text Available Salicylic acid, jasmonic acid, methyl salicylate, and methyl jasmonate are important phytohormones and defensive signaling compounds, so it is of great importance to determine their levels rapidly and accurately. The study uses Ulmus pumila leaves infected by Tetraneura akinire Sasaki at different stages as materials; after extraction with 80% methanol and ethyl acetate and purification with primary secondary amine (PSA and graphitized carbon blacks (GCB, the contents of signal compounds salicylic acid, jasmonic acid, methyl salicylate, and methyl jasmonate were determined by GC-MS. The results showed that the level of salicylic acid, jasmonic acid, methyl salicylate, and methyl jasmonate increased remarkably in U. pumila once infected by T. akinire Sasaki, but the maximums of these four compounds occurred at different times. Salicylic acid level reached the highest at the early stage, and jasmonic acid level went to the maximum in the middle stage; by contrast, change of content of methyl salicylate and methyl jasmonate was the quite opposite.

  10. Simultaneous Determination of Salicylic Acid, Jasmonic Acid, Methyl Salicylate, and Methyl Jasmonate from Ulmus pumila Leaves by GC-MS.

    Huang, Zhi-Hong; Wang, Zhi-Li; Shi, Bao-Lin; Wei, Dong; Chen, Jian-Xin; Wang, Su-Li; Gao, Bao-Jia

    2015-01-01

    Salicylic acid, jasmonic acid, methyl salicylate, and methyl jasmonate are important phytohormones and defensive signaling compounds, so it is of great importance to determine their levels rapidly and accurately. The study uses Ulmus pumila leaves infected by Tetraneura akinire Sasaki at different stages as materials; after extraction with 80% methanol and ethyl acetate and purification with primary secondary amine (PSA) and graphitized carbon blacks (GCB), the contents of signal compounds salicylic acid, jasmonic acid, methyl salicylate, and methyl jasmonate were determined by GC-MS. The results showed that the level of salicylic acid, jasmonic acid, methyl salicylate, and methyl jasmonate increased remarkably in U. pumila once infected by T. akinire Sasaki, but the maximums of these four compounds occurred at different times. Salicylic acid level reached the highest at the early stage, and jasmonic acid level went to the maximum in the middle stage; by contrast, change of content of methyl salicylate and methyl jasmonate was the quite opposite.

  11. Ethylene signaling renders the jasmonate response of Arabidopsis insensitive to future suppression by salicylic Acid.

    Leon-Reyes, Antonio; Du, Yujuan; Koornneef, Annemart; Proietti, Silvia; Körbes, Ana P; Memelink, Johan; Pieterse, Corné M J; Ritsema, Tita

    2010-02-01

    Cross-talk between jasmonate (JA), ethylene (ET), and Salicylic acid (SA) signaling is thought to operate as a mechanism to fine-tune induced defenses that are activated in response to multiple attackers. Here, 43 Arabidopsis genotypes impaired in hormone signaling or defense-related processes were screened for their ability to express SA-mediated suppression of JA-responsive gene expression. Mutant cev1, which displays constitutive expression of JA and ET responses, appeared to be insensitive to SA-mediated suppression of the JA-responsive marker genes PDF1.2 and VSP2. Accordingly, strong activation of JA and ET responses by the necrotrophic pathogens Botrytis cinerea and Alternaria brassicicola prior to SA treatment counteracted the ability of SA to suppress the JA response. Pharmacological assays, mutant analysis, and studies with the ET-signaling inhibitor 1-methylcyclopropene revealed that ET signaling renders the JA response insensitive to subsequent suppression by SA. The APETALA2/ETHYLENE RESPONSE FACTOR transcription factor ORA59, which regulates JA/ET-responsive genes such as PDF1.2, emerged as a potential mediator in this process. Collectively, our results point to a model in which simultaneous induction of the JA and ET pathway renders the plant insensitive to future SA-mediated suppression of JA-dependent defenses, which may prioritize the JA/ET pathway over the SA pathway during multi-attacker interactions.

  12. Rewiring of the jasmonic acid signaling pathway during insect herbivory on Arabidopsis

    Verhage, A.

    2011-01-01

    Plants are attacked by a plethora of potentially devastating pathogens and pests. To protect themselves, plants have evolved a sophisticated immune system in which phytohormones play pivotal regulatory roles. Jasmonic acid (JA) emerged as an important hormonal regulator of defense responses that are

  13. Interaction of plant cell signaling molecules, salicylic acid and jasmonic acid, with the mitochondria of Helicoverpa armigera.

    Akbar, S M D; Sharma, H C; Jayalakshmi, S K; Sreeramulu, K

    2012-02-01

    The cotton bollworm, Helicoverpa armigera is a polyphagous pest in Asia, Africa, and the Mediterranean Europe. Salicylic acid (SA) and jasmonic acid (JA) are the cell signaling molecules produced in response to insect attack in plants. The effect of these signaling molecules was investigated on the oxidative phosphorylation and oxidative stress of H. armigera. SA significantly inhibited the state III and state IV respiration, respiratory control index (RCI), respiratory complexes I and II, induced mitochondrial swelling, and cytochrome c release in vitro. Under in vivo conditions, SA induced state IV respiration as well as oxidative stress in time- and dose-dependent manner, and also inhibited the larval growth. In contrast, JA did not affect the mitochondrial respiration and oxidative stress. SA affected the growth and development of H. armigera, in addition to its function as signaling molecules involved in both local defense reactions at feeding sites and the induction of systemic acquired resistance in plants.

  14. Radioimmunoassay for jasmonic acid

    Knoefel, H.D.; Brueckner, C.; Kramell, R.; Sembdner, G.; Schreiber, K. (Akademie der Wissenschaften der DDR, Halle/Saale. Inst. fuer Biochemie der Pflanzen)

    1984-01-01

    A radioimmunoassay (RIA) for the natural plant growth regulator jasmonic acid (JA) was developed. The antiserum was raised in rabbits against (+-)-JA linked to bovine serum albumin. As tracer tritium labelled (+-)-JA (spec. act. 7.4 x 10/sup 9/ Bq x mmol/sup -1/) was used. Cross-reactivity studies with compounds structurally related to JA demonstrated the antiserum to be specific for JA, abscisic acid normally present in the same extract does not interfer. The RIA has a detection limit of 2 ng (-)-JA methylester, a measuring range 2-200 ng, and no extensive purification is required prior to estimation. Therefore, in JA analysis the RIA described is superior to GC, HPLC, and bioassay. This new method has been employed for studies on the distribution of JA in different plant organs of the broad bean, Vicia faba L.

  15. Salicylic acid suppresses jasmonic acid signaling downstream of SCFCOI1-JAZ by targeting GCC promoter motifs via transcription factor ORA59

    Does, D. van der; Leon-Reyes, A.; Koornneef, A.; Verk, M.C. van; Rodenburg, N.; Pauwels, L.; Goossens, A.; Körbes, A.P.; Memelink, J.; Ritsema, T.; Wees, S.C.M. van; Pieterse, C.M.J.

    2013-01-01

    Antagonism between the defense hormones salicylic acid (SA) and jasmonic acid (JA) plays a central role in the modulation of the plant immune signaling network, but the molecular mechanisms underlying this phenomenon are largely unknown. Here, we demonstrate that suppression of the JA pathway by SA

  16. The plastidial retrograde signal methyl erythritol cyclopyrophosphate is a regulator of salicylic acid and jasmonic acid crosstalk

    Lemos, Mark; Xiao, Yanmei; Bjornson, Marta; Wang, Jin-zheng; Hicks, Derrick; de Souza, Amancio; Wang, Chang-Quan; Yang, Panyu; Ma, Shisong; Dinesh-Kumar, Savithramma; Dehesh, Katayoon

    2016-01-01

    The exquisite harmony between hormones and their corresponding signaling pathways is central to prioritizing plant responses to simultaneous and/or successive environmental trepidations. The crosstalk between jasmonic acid (JA) and salicylic acid (SA) is an established effective mechanism that optimizes and tailors plant adaptive responses. However, the underlying regulatory modules of this crosstalk are largely unknown. Global transcriptomic analyses of mutant plants (ceh1) with elevated levels of the stress-induced plastidial retrograde signaling metabolite 2-C-methyl-D-erythritol cyclopyrophosphate (MEcPP) revealed robustly induced JA marker genes, expected to be suppressed by the presence of constitutively high SA levels in the mutant background. Analyses of a range of genotypes with varying SA and MEcPP levels established the selective role of MEcPP-mediated signal(s) in induction of JA-responsive genes in the presence of elevated SA. Metabolic profiling revealed the presence of high levels of the JA precursor 12-oxo-phytodienoic acid (OPDA), but near wild type levels of JA in the ceh1 mutant plants. Analyses of coronatine-insensitive 1 (coi1)/ceh1 double mutant plants confirmed that the MEcPP-mediated induction is JA receptor COI1 dependent, potentially through elevated OPDA. These findings identify MEcPP as a previously unrecognized central regulatory module that induces JA-responsive genes in the presence of high SA, thereby staging a multifaceted plant response within the environmental context. PMID:26733689

  17. Defense to Sclerotinia sclerotiorum in oilseed rape is associated with the sequential activations of salicylic acid signaling and jasmonic acid signaling.

    Wang, Zheng; Tan, Xiaoli; Zhang, Zhiyan; Gu, Shoulai; Li, Guanying; Shi, Haifeng

    2012-03-01

    Signaling pathways mediated by salicylic acid (SA) and jasmonic acid (JA) are widely studied in various host-pathogen interactions. For oilseed rape (Brassica napus)-Sclerotinia sclerotiorum interaction, little information of the two signaling molecules has been described in detail. In this study, we showed that the level of SA and JA in B. napus leaves was increased with a distinct temporal profile, respectively, after S. sclerotiorum infection. The application of SA or methyl jasmonate enhanced the resistance to the pathogen. Furthermore, a set of SA and JA signaling marker genes were identified from B. napus and were used to monitor the signaling responses to S. sclerotiorum infection by examining the temporal expression profiles of these marker genes. The SA signaling was activated within 12h post inoculation (hpi) followed by the JA signaling which was activated around 24 hpi. In addition, SA-JA crosstalk genes were activated during this process. These results suggested that defense against S. sclerotiorum in oilseed rape is associated with a sequential activation of SA signaling and JA signaling, which provide important clues for designing strategies to curb diseases caused by S. sclerotioru. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

  18. Involvement of salicylic acid, ethylene and jasmonic acid signalling pathways in the susceptibility of tomato to Fusarium oxysporum

    Di, X.; Gomila, J.; Takken, F.L.W.

    Phytohormones, such as salicylic acid (SA), ethylene (ET) and jasmonic acid (JA), play key roles in plant defence following pathogen attack. The involvement of these hormones in susceptibility following Fusarium oxysporum (Fo) infection has mostly been studied in Arabidopsis thaliana. However, Fo

  19. The plastidial retrograde signal methyl erythritol cyclopyrophosphate is a regulator of salicylic acid and jasmonic acid crosstalk.

    Lemos, Mark; Xiao, Yanmei; Bjornson, Marta; Wang, Jin-Zheng; Hicks, Derrick; Souza, Amancio de; Wang, Chang-Quan; Yang, Panyu; Ma, Shisong; Dinesh-Kumar, Savithramma; Dehesh, Katayoon

    2016-03-01

    The exquisite harmony between hormones and their corresponding signaling pathways is central to prioritizing plant responses to simultaneous and/or successive environmental trepidations. The crosstalk between jasmonic acid (JA) and salicylic acid (SA) is an established effective mechanism that optimizes and tailors plant adaptive responses. However, the underlying regulatory modules of this crosstalk are largely unknown. Global transcriptomic analyses of mutant plants (ceh1) with elevated levels of the stress-induced plastidial retrograde signaling metabolite 2-C-methyl-D-erythritol cyclopyrophosphate (MEcPP) revealed robustly induced JA marker genes, expected to be suppressed by the presence of constitutively high SA levels in the mutant background. Analyses of a range of genotypes with varying SA and MEcPP levels established the selective role of MEcPP-mediated signal(s) in induction of JA-responsive genes in the presence of elevated SA. Metabolic profiling revealed the presence of high levels of the JA precursor 12-oxo-phytodienoic acid (OPDA), but near wild type levels of JA in the ceh1 mutant plants. Analyses of coronatine-insensitive 1 (coi1)/ceh1 double mutant plants confirmed that the MEcPP-mediated induction is JA receptor COI1 dependent, potentially through elevated OPDA. These findings identify MEcPP as a previously unrecognized central regulatory module that induces JA-responsive genes in the presence of high SA, thereby staging a multifaceted plant response within the environmental context. © The Author 2016. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  20. Effects of jasmonic acid, ethylene, and salicylic acid signaling on the rhizosphere bacterial community of Arabidopsis thaliana.

    Doornbos, Rogier F; Geraats, Bart P J; Kuramae, Eiko E; Van Loon, L C; Bakker, Peter A H M

    2011-04-01

    Systemically induced resistance is a promising strategy to control plant diseases, as it affects numerous pathogens. However, since induced resistance reduces one or both growth and activity of plant pathogens, the indigenous microflora may also be affected by an enhanced defensive state of the plant. The aim of this study was to elucidate how much the bacterial rhizosphere microflora of Arabidopsis is affected by induced systemic resistance (ISR) or systemic acquired resistance (SAR). Therefore, the bacterial microflora of wild-type plants and plants affected in their defense signaling was compared. Additionally, ISR was induced by application of methyl jasmonate and SAR by treatment with salicylic acid or benzothiadiazole. As a comparative model, we also used wild type and ethylene-insensitive tobacco. Some of the Arabidopsis genotypes affected in defense signaling showed altered numbers of culturable bacteria in their rhizospheres; however, effects were dependent on soil type. Effects of plant genotype on rhizosphere bacterial community structure could not be related to plant defense because chemical activation of ISR or SAR had no significant effects on density and structure of the rhizosphere bacterial community. These findings support the notion that control of plant diseases by elicitation of systemic resistance will not significantly affect the resident soil bacterial microflora.

  1. The Ubiquitin System and Jasmonate Signaling

    Astrid Nagels Durand

    2016-01-01

    Full Text Available The ubiquitin (Ub system is involved in most, if not all, biological processes in eukaryotes. The major specificity determinants of this system are the E3 ligases, which bind and ubiquitinate specific sets of proteins and are thereby responsible for target recruitment to the proteasome or other cellular processing machineries. The Ub system contributes to the regulation of the production, perception and signal transduction of plant hormones. Jasmonic acid (JA and its derivatives, known as jasmonates (JAs, act as signaling compounds regulating plant development and plant responses to various biotic and abiotic stress conditions. We provide here an overview of the current understanding of the Ub system involved in JA signaling.

  2. The crosstalk between Target of Rapamycin (TOR) and Jasmonic Acid (JA) signaling existing in Arabidopsis and cotton.

    Song, Yun; Zhao, Ge; Zhang, Xueyan; Li, Linxuan; Xiong, Fangjie; Zhuo, Fengping; Zhang, Chaojun; Yang, Zuoren; Datla, Raju; Ren, Maozhi; Li, Fuguang

    2017-04-04

    Target of rapamycin (TOR) acts as an important regulator of cell growth, development and stress responses in most examined diploid eukaryotes. However, little is known about TOR in tetraploid species such as cotton. Here, we show that TORC1-S6K-RPS6, the major signaling components, are conserved and further expanded in cotton genome. Though the cotton seedlings are insensitive to rapamycin, AZD8055, the second-generation inhibitor of TOR, can significantly suppress the growth in cotton. Global transcriptome analysis revealed that genes associated with jasmonic acid (JA) biosynthesis and transduction were significantly altered in AZD8055 treated cotton seedlings, suggesting the potential crosstalk between TOR and JA signaling. Pharmacological and genetic approaches have been employed to get further insights into the molecular mechanism of the crosstalk between TOR and JA. Combination of AZD8055 with methyl jasmonate can synergistically inhibit cotton growth, and additionally JA levels were significantly increased when cotton seedlings were subjected to AZD8055. JA biosynthetic and signaling mutants including jar1, coi1-2 and myc2-2 displayed TOR inhibitor-resistant phenotypes, whereas COI1 overexpression transgenic lines and jaz10 exhibited sensitivity to AZD8055. Consistently, cotton JAZ can partially rescue TOR-suppressed phenotypes in Arabidopsis. These evidences revealed that the crosstalk between TOR and JA pathway operates in cotton and Arabidopsis.

  3. Involvement of salicylic acid, ethylene and jasmonic acid signalling pathways in the susceptibility of tomato to Fusarium oxysporum.

    Di, Xiaotang; Gomila, Jo; Takken, Frank L W

    2017-09-01

    Phytohormones, such as salicylic acid (SA), ethylene (ET) and jasmonic acid (JA), play key roles in plant defence following pathogen attack. The involvement of these hormones in susceptibility following Fusarium oxysporum (Fo) infection has mostly been studied in Arabidopsis thaliana. However, Fo causes vascular wilt disease in a broad range of crops, including tomato (Solanum lycopersicum). Surprisingly little is known about the involvement of these phytohormones in the susceptibility of tomato towards Fo f. sp. lycopersici (Fol). Here, we investigate their involvement by the analysis of the expression of ET, JA and SA marker genes following Fol infection, and by bioassays of tomato mutants affected in either hormone production or perception. Fol inoculation triggered the expression of SA and ET marker genes, showing the activation of these pathways. NahG tomato, in which SA is degraded, became hypersusceptible to Fol infection and showed stronger disease symptoms than wild-type. In contrast, ACD and Never ripe (Nr) mutants, in which ET biosynthesis and perception, respectively, are impaired, showed decreased disease symptoms and reduced fungal colonization on infection. The susceptibility of the def1 tomato mutant, and a prosystemin over-expressing line, in which JA signalling is compromised or constitutively activated, respectively, was unaltered. Our results show that SA is a negative and ET a positive regulator of Fol susceptibility. The SA and ET signalling pathways appear to act synergistically, as an intact ET pathway is required for the induction of an SA marker gene, and vice versa. © 2017 THE AUTHORS. MOLECULAR PLANT PATHOLOGY PUBLISHED BY BRITISH SOCIETY FOR PLANT PATHOLOGY AND JOHN WILEY & SONS LTD.

  4. Non-pathogenic rhizobacteria interfere with the attraction of parasitoids to aphid-induced plant volatiles via jasmonic acid signalling.

    Pineda, Ana; Soler, Roxina; Weldegergis, Berhane T; Shimwela, Mpoki M; VAN Loon, Joop J A; Dicke, Marcel

    2013-02-01

    Beneficial soil-borne microbes, such as mycorrhizal fungi or rhizobacteria, can affect the interactions of plants with aboveground insects at several trophic levels. While the mechanisms of interactions with herbivorous insects, that is, the second trophic level, are starting to be understood, it remains unknown how plants mediate the interactions between soil microbes and carnivorous insects, that is, the third trophic level. Using Arabidopsis thaliana Col-0 and the aphid Myzus persicae, we evaluate here the underlying mechanisms involved in the plant-mediated interaction between the non-pathogenic rhizobacterium Pseudomonas fluorescens and the parasitoid Diaeretiella rapae, by combining ecological, chemical and molecular approaches. Rhizobacterial colonization modifies the composition of the blend of herbivore-induced plant volatiles. The volatile blend from rhizobacteria-treated aphid-infested plants is less attractive to an aphid parasitoid, in terms of both olfactory preference behaviour and oviposition, than the volatile blend from aphid-infested plants without rhizobacteria. Importantly, the effect of rhizobacteria on both the emission of herbivore-induced volatiles and parasitoid response to aphid-infested plants is lost in an Arabidopsis mutant (aos/dde2-2) that is impaired in jasmonic acid production. By modifying the blend of herbivore-induced plant volatiles that depend on the jasmonic acid-signalling pathway, root-colonizing microbes interfere with the attraction of parasitoids of leaf herbivores. © 2012 Blackwell Publishing Ltd.

  5. DOES JASMONIC ACID PREVENT THE GERMINATION

    ÇAVUŞOĞLU, Kürşat

    2009-01-01

    Abstract: Effect of jasmonic acid on seed germination and seedling growth of barley (Hordeum vulgare L. cv. Bülbül 89) was investigated in the present study. Jasmonic acid concentrations less than 1500 µM have not inhibited the seed germination, while 1500 and 2000 µM jasmonic acid levels caused atypical germination. The germination was completely inhibited at 3000 µM level of jasmonic acid. However, the seedling growth clearly slowed down with increasing concentrations of jasmonic acid. Furt...

  6. AtMYB44 regulates WRKY70 expression and modulates antagonistic interaction between salicylic acid and jasmonic acid signaling.

    Shim, Jae Sung; Jung, Choonkyun; Lee, Sangjoon; Min, Kyunghun; Lee, Yin-Won; Choi, Yeonhee; Lee, Jong Seob; Song, Jong Tae; Kim, Ju-Kon; Choi, Yang Do

    2013-02-01

    The role of AtMYB44, an R2R3 MYB transcription factor, in signaling mediated by jasmonic acid (JA) and salicylic acid (SA) is examined. AtMYB44 is induced by JA through CORONATINE INSENSITIVE 1 (COI1). AtMYB44 over-expression down-regulated defense responses against the necrotrophic pathogen Alternaria brassicicola, but up-regulated WRKY70 and PR genes, leading to enhanced resistance to the biotrophic pathogen Pseudomonas syringae pv. tomato DC3000. The knockout mutant atmyb44 shows opposite effects. Induction of WRKY70 by SA is reduced in atmyb44 and npr1-1 mutants, and is totally abolished in atmyb44 npr1-1 double mutants, showing that WRKY70 is regulated independently through both NPR1 and AtMYB44. AtMYB44 over-expression does not change SA content, but AtMYB44 over-expression phenotypes, such as retarded growth, up-regulated PR1 and down-regulated PDF1.2 are reversed by SA depletion. The wrky70 mutation suppressed AtMYB44 over-expression phenotypes, including up-regulation of PR1 expression and down-regulation of PDF1.2 expression. β-estradiol-induced expression of AtMYB44 led to WRKY70 activation and thus PR1 activation. AtMYB44 binds to the WRKY70 promoter region, indicating that AtMYB44 acts as a transcriptional activator of WRKY70 by directly binding to a conserved sequence element in the WRKY70 promoter. These results demonstrate that AtMYB44 modulates antagonistic interaction by activating SA-mediated defenses and repressing JA-mediated defenses through direct control of WRKY70. © 2012 The Authors The Plant Journal © 2012 Blackwell Publishing Ltd.

  7. Defense Priming and Jasmonates: A Role for Free Fatty Acids in Insect Elicitor-Induced Long Distance Signaling

    Ting Li

    2016-01-01

    Full Text Available Green leaf volatiles (GLV prime plants against insect herbivore attack resulting in stronger and faster signaling by jasmonic acid (JA. In maize this response is specifically linked to insect elicitor (IE-induced signaling processes, which cause JA accumulation not only around the damage site, but also in distant tissues, presumably through the activation of electrical signals. Here, we present additional data further characterizing these distal signaling events in maize. Also, we describe how exposure to GLV increases free fatty acid (fFA levels in maize seedlings, but also in other plants, and how increased fFA levels affect IE-induced JA accumulation. Increased fFA, in particular α-linolenic acid (LnA, caused a significant increase in JA accumulation after IE treatment, while JA induced by mechanical wounding (MW alone was not affected. We also identified treatments that significantly decreased certain fFA level including simulated wind and rain. In such treated plants, IE-induced JA accumulation was significantly reduced when compared to un-moved control plants, while MW-induced JA accumulation was not significantly affected. Since only IE-induced JA accumulation was altered by changes in the fFA composition, we conclude that changing levels of fFA affect primarily IE-induced signaling processes rather than serving as a substrate for JA.

  8. Defense Priming and Jasmonates: A Role for Free Fatty Acids in Insect Elicitor-Induced Long Distance Signaling

    Li, Ting; Cofer, Tristan; Engelberth, Marie; Engelberth, Jurgen

    2016-01-01

    Green leaf volatiles (GLV) prime plants against insect herbivore attack resulting in stronger and faster signaling by jasmonic acid (JA). In maize this response is specifically linked to insect elicitor (IE)-induced signaling processes, which cause JA accumulation not only around the damage site, but also in distant tissues, presumably through the activation of electrical signals. Here, we present additional data further characterizing these distal signaling events in maize. Also, we describe how exposure to GLV increases free fatty acid (fFA) levels in maize seedlings, but also in other plants, and how increased fFA levels affect IE-induced JA accumulation. Increased fFA, in particular α-linolenic acid (LnA), caused a significant increase in JA accumulation after IE treatment, while JA induced by mechanical wounding (MW) alone was not affected. We also identified treatments that significantly decreased certain fFA level including simulated wind and rain. In such treated plants, IE-induced JA accumulation was significantly reduced when compared to un-moved control plants, while MW-induced JA accumulation was not significantly affected. Since only IE-induced JA accumulation was altered by changes in the fFA composition, we conclude that changing levels of fFA affect primarily IE-induced signaling processes rather than serving as a substrate for JA. PMID:27135225

  9. Signal transduction downstream of salicylic and jasmonic acid in herbivory-induced parasitoid attraction by Arabidopsis is independent of JAR1 and NPR1

    Poecke, van R.M.P.; Dicke, M.

    2003-01-01

    Plants can defend themselves indirectly against herbivores by emitting a volatile blend upon herbivory that attracts the natural enemies of these herbivores, either predators or parasitoids. Although signal transduction in plants from herbivory to induced volatile production depends on jasmonic acid

  10. Analysis of defense signals in Arabidopsis thaliana leaves by ultra-performance liquid chromatography/tandem mass spectrometry: jasmonates, salicylic acid, abscisic acid.

    Stingl, Nadja; Krischke, Markus; Fekete, Agnes; Mueller, Martin J

    2013-01-01

    Defense signaling compounds and phytohormones play an essential role in the regulation of plant responses to various environmental abiotic and biotic stresses. Among the most severe stresses are herbivory, pathogen infection, and drought stress. The major hormones involved in the regulation of these responses are 12-oxo-phytodienoic acid (OPDA), the pro-hormone jasmonic acid (JA) and its biologically active isoleucine conjugate (JA-Ile), salicylic acid (SA), and abscisic acid (ABA). These signaling compounds are present and biologically active at very low concentrations from ng/g to μg/g dry weight. Accurate and sensitive quantification of these signals has made a significant contribution to the understanding of plant stress responses. Ultra-performance liquid chromatography (UPLC) coupled with a tandem quadrupole mass spectrometer (MS/MS) has become an essential technique for the analysis and quantification of these compounds.

  11. A pivotal role of the jasmonic acid signal pathway in mediating radiation-induced bystander effects in Arabidopsis thaliana

    Wang, Ting; Xu, Wei; Deng, Chenguang; Xu, Shaoxin; Li, Fanghua; Wu, Yuejin; Wu, Lijun [Key Laboratory of Ion Beam Bioengineering, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031 (China); Key Laboratory of Environmental Toxicology and Pollution Control Technology of Anhui Province, Hefei 230031 (China); Bian, Po, E-mail: bianpo@ipp.ac.cn [Key Laboratory of Ion Beam Bioengineering, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031 (China); Key Laboratory of Environmental Toxicology and Pollution Control Technology of Anhui Province, Hefei 230031 (China)

    2016-09-15

    Highlights: • The JA signal pathway plays a pivotal role in mediating radiation-induced bystander effects in Arabidopsis thaliana. • The JA signal pathway is involved in both the generation of bystander signals in irradiated roots and radiation responses in bystander aerial plants. • Over-accumulation of endogenous JA enhances the radiosensitivity of plants in terms of RIBE. - Abstract: Although radiation-induced bystander effects (RIBE) in Arabidopsis thaliana have been well demonstrated in vivo, little is known about their underlying mechanisms, particularly with regard to the participating signaling molecules and signaling pathways. In higher plants, jasmonic acid (JA) and its bioactive derivatives are well accepted as systemic signal transducers that are produced in response to various environmental stresses. It is therefore speculated that the JA signal pathway might play a potential role in mediating radiation-induced bystander signaling of root-to-shoot. In the present study, pretreatment of seedlings with Salicylhydroxamic acid, an inhibitor of lipoxigenase (LOX) in JA biosynthesis, significantly suppressed RIBE-mediated expression of the AtRAD54 gene. After root irradiation, the aerial parts of A. thaliana mutants deficient in JA biosynthesis (aos) and signaling cascades (jar1-1) showed suppressed induction of the AtRAD54 and AtRAD51 genes and TSI and 180-bp repeats, which have been extensively used as endpoints of bystander genetic and epigenetic effects in plants. These results suggest an involvement of the JA signal pathway in the RIBE of plants. Using the root micro-grafting technique, the JA signal pathway was shown to participate in both the generation of bystander signals in irradiated root cells and radiation responses in the bystander aerial parts of plants. The over-accumulation of endogenous JA in mutant fatty acid oxygenation up-regulated 2 (fou2), in which mutation of the Two Pore Channel 1 (TPC1) gene up-regulates expression of the LOX

  12. Simultaneous Determination of Salicylic Acid, Jasmonic Acid, Methyl Salicylate, and Methyl Jasmonate from Ulmus pumila Leaves by GC-MS

    Huang, Zhi-hong; Wang, Zhi-li; Shi, Bao-lin; Wei, Dong; Chen, Jian-xin; Wang, Su-li; Gao, Bao-jia

    2015-01-01

    Salicylic acid, jasmonic acid, methyl salicylate, and methyl jasmonate are important phytohormones and defensive signaling compounds, so it is of great importance to determine their levels rapidly and accurately. The study uses Ulmus pumila leaves infected by Tetraneura akinire Sasaki at different stages as materials; after extraction with 80% methanol and ethyl acetate and purification with primary secondary amine (PSA) and graphitized carbon blacks (GCB), the contents of signal compounds sa...

  13. Phospholipidic signaling and vanillin production in response to salicylic acid and methyl jasmonate in Capsicum chinense J. cells.

    Altúzar-Molina, Alma R; Muñoz-Sánchez, J Armando; Vázquez-Flota, Felipe; Monforte-González, Miriam; Racagni-Di Palma, Graciela; Hernández-Sotomayor, S M Teresa

    2011-02-01

    The phospholipidic signal transduction system involves generation of second messengers by hydrolysis or changes in phosphorylation state. Several studies have shown that the signaling pathway forms part of plant response to phytoregulators such as salicylic acid (SA) and methyl jasmonate (MJ), which have been widely used to stimulate secondary metabolite production in cell cultures. An evaluation was made of the effect of SA and MJ on phospholipidic signaling and capsaicinoid production in Capsicum chinense Jacq. suspension cells. Treatment with SA inhibited phospholipase C (PLC) (EC: 3.1.4.3) and phospholipase D (PLD) (EC: 3.1.4.4) activities in vitro, but increased lipid kinase activities in vitro at different SA concentrations. Treatment with MJ produced increases in PLC and PLD activities, while lipid kinase activities were variable and dose-dependent. The production of vanillin, a precursor of capsaicinoids, increased at specific SA or MJ doses. Preincubation with neomycin, a phospholipase inhibitor, before SA or MJ treatment inhibits increase in vanillin production which suggests that phospholipidic second messengers may participate in the observed increase in vanillin production. Copyright © 2010 Elsevier Masson SAS. All rights reserved.

  14. A pivotal role of the jasmonic acid signal pathway in mediating radiation-induced bystander effects in Arabidopsis thaliana.

    Wang, Ting; Xu, Wei; Deng, Chenguang; Xu, Shaoxin; Li, Fanghua; Wu, Yuejin; Wu, Lijun; Bian, Po

    Although radiation-induced bystander effects (RIBE) in Arabidopsis thaliana have been well demonstrated in vivo, little is known about their underlying mechanisms, particularly with regard to the participating signaling molecules and signaling pathways. In higher plants, jasmonic acid (JA) and its bioactive derivatives are well accepted as systemic signal transducers that are produced in response to various environmental stresses. It is therefore speculated that the JA signal pathway might play a potential role in mediating radiation-induced bystander signaling of root-to-shoot. In the present study, pretreatment of seedlings with Salicylhydroxamic acid, an inhibitor of lipoxigenase (LOX) in JA biosynthesis, significantly suppressed RIBE-mediated expression of the AtRAD54 gene. After root irradiation, the aerial parts of A. thaliana mutants deficient in JA biosynthesis (aos) and signaling cascades (jar1-1) showed suppressed induction of the AtRAD54 and AtRAD51 genes and TSI and 180-bp repeats, which have been extensively used as endpoints of bystander genetic and epigenetic effects in plants. These results suggest an involvement of the JA signal pathway in the RIBE of plants. Using the root micro-grafting technique, the JA signal pathway was shown to participate in both the generation of bystander signals in irradiated root cells and radiation responses in the bystander aerial parts of plants. The over-accumulation of endogenous JA in mutant fatty acid oxygenation up-regulated 2 (fou2), in which mutation of the Two Pore Channel 1 (TPC1) gene up-regulates expression of the LOX and allene oxide synthase (AOS) genes, inhibited RIBE-mediated expression of the AtRAD54 gene, but up-regulated expression of the AtKU70 and AtLIG4 genes in the non-homologous end joining (NHEJ) pathway. Considering that NHEJ is employed by plants with increased DNA damage, the switch from HR to NHEJ suggests that over-accumulation of endogenous JA might enhance the radiosensitivity of plants

  15. N,N-dimethyl hexadecylamine and related amines regulate root morphogenesis via jasmonic acid signaling in Arabidopsis thaliana.

    Raya-González, Javier; Velázquez-Becerra, Crisanto; Barrera-Ortiz, Salvador; López-Bucio, José; Valencia-Cantero, Eduardo

    2017-05-01

    Plant growth-promoting rhizobacteria are natural inhabitants of roots, colonize diverse monocot and dicot species, and affect several functional traits such as root architecture, adaptation to adverse environments, and protect plants from pathogens. N,N-dimethyl-hexadecylamine (C16-DMA) is a rhizobacterial amino lipid that modulates the postembryonic development of several plants, likely as part of volatile blends. In this work, we evaluated the bioactivity of C16-DMA and other related N,N-dimethyl-amines with varied length and found that inhibition of primary root growth was related to the length of the acyl chain. C16-DMA inhibited primary root growth affecting cell division and elongation, while promoting lateral root formation and root hair growth and density in Arabidopsis thaliana (Arabidopsis) wild-type (WT) seedlings. Interestingly, C16-DMA induced the expression of the jasmonic acid (JA)-responsive gene marker pLOX2:uidA, while JA-related mutants jar1, coi1-1, and myc2 affected on JA biosynthesis and perception, respectively, are compromised in C16-DMA responses. Comparison of auxin-regulated gene expression, root architectural changes in WT, and auxin-related mutants aux1-7, tir1/afb2/afb3, and arf7-1/arf19-1 to C16-DMA shows that the C16-DMA effects occur independently of auxin signaling. Together, these results reveal a novel class of aminolipids modulating root organogenesis via crosstalk with the JA signaling pathway.

  16. Heterotrimeric G proteins-mediated resistance to necrotrophic pathogens includes mechanisms independent of salicylic acid-, jasmonic acid/ethylene- and abscisic acid-mediated defense signaling.

    Trusov, Yuri; Sewelam, Nasser; Rookes, James Edward; Kunkel, Matt; Nowak, Ekaterina; Schenk, Peer Martin; Botella, José Ramón

    2009-04-01

    Heterotrimeric G proteins are involved in the defense response against necrotrophic fungi in Arabidopsis. In order to elucidate the resistance mechanisms involving heterotrimeric G proteins, we analyzed the effects of the Gβ (subunit deficiency in the mutant agb1-2 on pathogenesis-related gene expression, as well as the genetic interaction between agb1-2 and a number of mutants of established defense pathways. Gβ-mediated signaling suppresses the induction of salicylic acid (SA)-, jasmonic acid (JA)-, ethylene (ET)- and abscisic acid (ABA)-dependent genes during the initial phase of the infection with Fusarium oxysporum (up to 48 h after inoculation). However, at a later phase it enhances JA/ET-dependent genes such as PDF1.2 and PR4. Quantification of the Fusarium wilt symptoms revealed that Gβ- and SA-deficient mutants were more susceptible than wild-type plants, whereas JA- and ET-insensitive and ABA-deficient mutants demonstrated various levels of resistance. Analysis of the double mutants showed that the Gβ-mediated resistance to F. oxysporum and Alternaria brassicicola was mostly independent of all of the previously mentioned pathways. However, the progressive decay of agb1-2 mutants was compensated by coi1-21 and jin1-9 mutations, suggesting that at this stage of F. oxysporum infection Gβ acts upstream of COI1 and ATMYC2 in JA signaling. © 2008 The Authors. Journal compilation © 2008 Blackwell Publishing Ltd.

  17. Salicylic acid receptors activate jasmonic acid signalling through a non-canonical pathway to promote effector-triggered immunity.

    Liu, Lijing; Sonbol, Fathi-Mohamed; Huot, Bethany; Gu, Yangnan; Withers, John; Mwimba, Musoki; Yao, Jian; He, Sheng Yang; Dong, Xinnian

    2016-10-11

    It is an apparent conundrum how plants evolved effector-triggered immunity (ETI), involving programmed cell death (PCD), as a major defence mechanism against biotrophic pathogens, because ETI-associated PCD could leave them vulnerable to necrotrophic pathogens that thrive on dead host cells. Interestingly, during ETI, the normally antagonistic defence hormones, salicylic acid (SA) and jasmonic acid (JA) associated with defence against biotrophs and necrotrophs respectively, both accumulate to high levels. In this study, we made the surprising finding that JA is a positive regulator of RPS2-mediated ETI. Early induction of JA-responsive genes and de novo JA synthesis following SA accumulation is activated through the SA receptors NPR3 and NPR4, instead of the JA receptor COI1. We provide evidence that NPR3 and NPR4 may mediate this effect by promoting degradation of the JA transcriptional repressor JAZs. This unique interplay between SA and JA offers a possible explanation of how plants can mount defence against a biotrophic pathogen without becoming vulnerable to necrotrophic pathogens.

  18. Integration of ethylene and jasmonic acid signaling pathways in the expression of maize defense protein Mir1-CP.

    Ankala, A; Luthe, D S; Williams, W P; Wilkinson, J R

    2009-12-01

    In plants, ethylene and jasmonate control the defense responses to multiple stressors, including insect predation. Among the defense proteins known to be regulated by ethylene is maize insect resistance 1-cysteine protease (Mir1-CP). This protein is constitutively expressed in the insect-resistant maize (Zea mays) genotype Mp708; however, its abundance significantly increases during fall armyworm (Spodoptera frugiperda) herbivory. Within 1 h of herbivory by fall armyworm, Mir1-CP accumulates at the feeding site and continues to increase in abundance until 24 h without any increase in its transcript (mir1) levels. To resolve this discrepancy and elucidate the role of ethylene and jasmonate in the signaling of Mir1-CP expression, the effects of phytohormone biosynthesis and perception inhibitors on Mir1-CP expression were tested. Immunoblot analysis of Mir1-CP accumulation and quantitative reverse-transcriptase polymerase chain reaction examination of mir1 levels in these treated plants demonstrate that Mir1-CP accumulation is regulated by both transcript abundance and protein expression levels. The results also suggest that jasmonate functions upstream of ethylene in the Mir1-CP expression pathway, allowing for both low-level constitutive expression and a two-stage defensive response, an immediate response involving Mir1-CP accumulation and a delayed response inducing mir1 transcript expression.

  19. SlMAPK3 enhances tolerance to tomato yellow leaf curl virus (TYLCV) by regulating salicylic acid and jasmonic acid signaling in tomato (Solanum lycopersicum).

    Li, Yunzhou; Qin, Lei; Zhao, Jingjing; Muhammad, Tayeb; Cao, Hehe; Li, Hailiang; Zhang, Yan; Liang, Yan

    2017-01-01

    Several recent studies have reported on the role of mitogen-activated protein kinase (MAPK3) in plant immune responses. However, little is known about how MAPK3 functions in tomato (Solanum lycopersicum L.) infected with tomato yellow leaf curl virus (TYLCV). There is also uncertainty about the connection between plant MAPK3 and the salicylic acid (SA) and jasmonic acid (JA) defense-signaling pathways. The results of this study indicated that SlMAPK3 participates in the antiviral response against TYLCV. Tomato seedlings were inoculated with TYLCV to investigate the possible roles of SlMAPK1, SlMAPK2, and SlMAPK3 against this virus. Inoculation with TYLCV strongly induced the expression and the activity of all three genes. Silencing of SlMAPK1, SlMAPK2, and SlMAPK3 reduced tolerance to TYLCV, increased leaf H2O2 concentrations, and attenuated expression of defense-related genes after TYLCV infection, especially in SlMAPK3-silenced plants. Exogenous SA and methyl jasmonic acid (MeJA) both significantly induced SlMAPK3 expression in tomato leaves. Over-expression of SlMAPK3 increased the transcript levels of SA/JA-mediated defense-related genes (PR1, PR1b/SlLapA, SlPI-I, and SlPI-II) and enhanced tolerance to TYLCV. After TYLCV inoculation, the leaves of SlMAPK3 over-expressed plants compared with wild type plants showed less H2O2 accumulation and greater superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX) activity. Overall, the results suggested that SlMAPK3 participates in the antiviral response of tomato to TYLCV, and that this process may be through either the SA or JA defense-signaling pathways.

  20. SlMAPK3 enhances tolerance to tomato yellow leaf curl virus (TYLCV by regulating salicylic acid and jasmonic acid signaling in tomato (Solanum lycopersicum.

    Yunzhou Li

    Full Text Available Several recent studies have reported on the role of mitogen-activated protein kinase (MAPK3 in plant immune responses. However, little is known about how MAPK3 functions in tomato (Solanum lycopersicum L. infected with tomato yellow leaf curl virus (TYLCV. There is also uncertainty about the connection between plant MAPK3 and the salicylic acid (SA and jasmonic acid (JA defense-signaling pathways. The results of this study indicated that SlMAPK3 participates in the antiviral response against TYLCV. Tomato seedlings were inoculated with TYLCV to investigate the possible roles of SlMAPK1, SlMAPK2, and SlMAPK3 against this virus. Inoculation with TYLCV strongly induced the expression and the activity of all three genes. Silencing of SlMAPK1, SlMAPK2, and SlMAPK3 reduced tolerance to TYLCV, increased leaf H2O2 concentrations, and attenuated expression of defense-related genes after TYLCV infection, especially in SlMAPK3-silenced plants. Exogenous SA and methyl jasmonic acid (MeJA both significantly induced SlMAPK3 expression in tomato leaves. Over-expression of SlMAPK3 increased the transcript levels of SA/JA-mediated defense-related genes (PR1, PR1b/SlLapA, SlPI-I, and SlPI-II and enhanced tolerance to TYLCV. After TYLCV inoculation, the leaves of SlMAPK3 over-expressed plants compared with wild type plants showed less H2O2 accumulation and greater superoxide dismutase (SOD, peroxidase (POD, catalase (CAT, and ascorbate peroxidase (APX activity. Overall, the results suggested that SlMAPK3 participates in the antiviral response of tomato to TYLCV, and that this process may be through either the SA or JA defense-signaling pathways.

  1. Salicylic Acid Suppresses Jasmonic Acid Signaling Downstream of SCFCOI1-JAZ by Targeting GCC Promoter Motifs via Transcription Factor ORA59[C][W][OA

    Van der Does, Dieuwertje; Leon-Reyes, Antonio; Koornneef, Annemart; Van Verk, Marcel C.; Rodenburg, Nicole; Pauwels, Laurens; Goossens, Alain; Körbes, Ana P.; Memelink, Johan; Ritsema, Tita; Van Wees, Saskia C.M.; Pieterse, Corné M.J.

    2013-01-01

    Antagonism between the defense hormones salicylic acid (SA) and jasmonic acid (JA) plays a central role in the modulation of the plant immune signaling network, but the molecular mechanisms underlying this phenomenon are largely unknown. Here, we demonstrate that suppression of the JA pathway by SA functions downstream of the E3 ubiquitin-ligase Skip-Cullin-F-box complex SCFCOI1, which targets JASMONATE ZIM-domain transcriptional repressor proteins (JAZs) for proteasome-mediated degradation. In addition, neither the stability nor the JA-induced degradation of JAZs was affected by SA. In silico promoter analysis of the SA/JA crosstalk transcriptome revealed that the 1-kb promoter regions of JA-responsive genes that are suppressed by SA are significantly enriched in the JA-responsive GCC-box motifs. Using GCC:GUS lines carrying four copies of the GCC-box fused to the β-glucuronidase reporter gene, we showed that the GCC-box motif is sufficient for SA-mediated suppression of JA-responsive gene expression. Using plants overexpressing the GCC-box binding APETALA2/ETHYLENE RESPONSE FACTOR (AP2/ERF) transcription factors ERF1 or ORA59, we found that SA strongly reduces the accumulation of ORA59 but not that of ERF1. Collectively, these data indicate that the SA pathway inhibits JA signaling downstream of the SCFCOI1-JAZ complex by targeting GCC-box motifs in JA-responsive promoters via a negative effect on the transcriptional activator ORA59. PMID:23435661

  2. Salicylic acid suppresses jasmonic acid signaling downstream of SCFCOI1-JAZ by targeting GCC promoter motifs via transcription factor ORA59.

    Van der Does, Dieuwertje; Leon-Reyes, Antonio; Koornneef, Annemart; Van Verk, Marcel C; Rodenburg, Nicole; Pauwels, Laurens; Goossens, Alain; Körbes, Ana P; Memelink, Johan; Ritsema, Tita; Van Wees, Saskia C M; Pieterse, Corné M J

    2013-02-01

    Antagonism between the defense hormones salicylic acid (SA) and jasmonic acid (JA) plays a central role in the modulation of the plant immune signaling network, but the molecular mechanisms underlying this phenomenon are largely unknown. Here, we demonstrate that suppression of the JA pathway by SA functions downstream of the E3 ubiquitin-ligase Skip-Cullin-F-box complex SCF(COI1), which targets JASMONATE ZIM-domain transcriptional repressor proteins (JAZs) for proteasome-mediated degradation. In addition, neither the stability nor the JA-induced degradation of JAZs was affected by SA. In silico promoter analysis of the SA/JA crosstalk transcriptome revealed that the 1-kb promoter regions of JA-responsive genes that are suppressed by SA are significantly enriched in the JA-responsive GCC-box motifs. Using GCC:GUS lines carrying four copies of the GCC-box fused to the β-glucuronidase reporter gene, we showed that the GCC-box motif is sufficient for SA-mediated suppression of JA-responsive gene expression. Using plants overexpressing the GCC-box binding APETALA2/ETHYLENE RESPONSE FACTOR (AP2/ERF) transcription factors ERF1 or ORA59, we found that SA strongly reduces the accumulation of ORA59 but not that of ERF1. Collectively, these data indicate that the SA pathway inhibits JA signaling downstream of the SCF(COI1)-JAZ complex by targeting GCC-box motifs in JA-responsive promoters via a negative effect on the transcriptional activator ORA59.

  3. Gaseous 3-pentanol primes plant immunity against a bacterial speck pathogen, Pseudomonas syringae pv. tomato via salicylic acid and jasmonic acid-dependent signaling pathways in Arabidopsis.

    Song, Geun C; Choi, Hye K; Ryu, Choong-Min

    2015-01-01

    3-Pentanol is an active organic compound produced by plants and is a component of emitted insect sex pheromones. A previous study reported that drench application of 3-pentanol elicited plant immunity against microbial pathogens and an insect pest in crop plants. Here, we evaluated whether 3-pentanol and the derivatives 1-pentanol and 2-pentanol induced plant systemic resistance using the in vitro I-plate system. Exposure of Arabidopsis seedlings to 10 μM and 100 nM 3-pentanol evaporate elicited an immune response to Pseudomonas syringae pv. tomato DC3000. We performed quantitative real-time PCR to investigate the 3-pentanol-mediated Arabidopsis immune responses by determining Pathogenesis-Related (PR) gene expression levels associated with defense signaling through salicylic acid (SA), jasmonic acid (JA), and ethylene signaling pathways. The results show that exposure to 3-pentanol and subsequent pathogen challenge upregulated PDF1.2 and PR1 expression. Selected Arabidopsis mutants confirmed that the 3-pentanol-mediated immune response involved SA and JA signaling pathways and the NPR1 gene. Taken together, this study indicates that gaseous 3-pentanol triggers induced resistance in Arabidopsis by priming SA and JA signaling pathways. To our knowledge, this is the first report that a volatile compound of an insect sex pheromone triggers plant systemic resistance against a bacterial pathogen.

  4. Gaseous 3-pentanol primes plant immunity against a bacterial speck pathogen, Pseudomonas syringae pv. tomato via salicylic acid and jasmonic acid-dependent signaling pathways in Arabidopsis

    Geun Cheol eSong

    2015-10-01

    Full Text Available 3-Pentanol is an active organic compound produced by plants and is a component of emitted insect sex pheromones. A previous study reported that drench application of 3-pentanol elicited plant immunity against microbial pathogens and an insect pest in crop plants. Here, we evaluated whether 3-pentanol and the derivatives 1-pentanol and 2-pentanol induced plant systemic resistance using the in vitro I-plate system. Exposure of Arabidopsis seedlings to 10 M and 100 nM 3-pentanol evaporate elicited an immune response to Pseudomonas syringae pv. tomato DC3000. We performed quantitative real-time PCR to investigate the 3-pentanol-mediated Arabidopsis immune responses by determining Pathogenesis-Related (PR gene expression levels associated with defense signaling through SA, JA, and ethylene signaling pathways. The results show that exposure to 3-pentanol and subsequent pathogen challenge upregulated PDF1.2 and PR1 expression. Selected Arabidopsis mutants confirmed that the 3-pentanol-mediated immune response involved salicylic acid (SA and jasmonic acid (JA signaling pathways and the NPR1 gene. Taken together, this study indicates that gaseous 3-pentanol triggers induced resistance in Arabidopsis by priming SA and JA signaling pathways. To our knowledge, this is the first report that a volatile compound of an insect sex pheromone triggers plant systemic resistance against a bacterial pathogen.

  5. The sesquiterpene botrydial produced by Botrytis cinerea induces the hypersensitive response on plant tissues and its action is modulated by salicylic acid and jasmonic acid signaling.

    Rossi, Franco Rubén; Gárriz, Andrés; Marina, María; Romero, Fernando Matías; Gonzalez, María Elisa; Collado, Isidro González; Pieckenstain, Fernando Luis

    2011-08-01

    Botrytis cinerea, as a necrotrophic fungus, kills host tissues and feeds on the remains. This fungus is able to induce the hypersensitive response (HR) on its hosts, thus taking advantage on the host's defense machinery for generating necrotic tissues. However, the identity of HR effectors produced by B. cinerea is not clear. The aim of this work was to determine whether botrydial, a phytotoxic sesquiterpene produced by B. cinerea, is able to induce the HR on plant hosts, using Arabidopsis thaliana as a model. Botrydial induced the expression of the HR marker HSR3, callose deposition, and the accumulation of reactive oxygen species and phenolic compounds. Botrydial also induced the expression of PR1 and PDF1.2, two pathogenesis-related proteins involved in defense responses regulated by salicylic acid (SA) and jasmonic acid (JA), respectively. A. thaliana and tobacco plants defective in SA signaling were more resistant to botrydial than wild-type plants, as opposed to A. thaliana plants defective in JA signaling, which were more sensitive. It can be concluded that botrydial induces the HR on its hosts and its effects are modulated by host signaling pathways mediated by SA and JA.

  6. Physcomitrella patens activates reinforcement of the cell wall, programmed cell death and accumulation of evolutionary conserved defence signals, such as salicylic acid and 12-oxo-phytodienoic acid, but not jasmonic acid, upon Botrytis cinerea infection.

    Ponce De León, Inés; Schmelz, Eric A; Gaggero, Carina; Castro, Alexandra; Álvarez, Alfonso; Montesano, Marcos

    2012-10-01

    The moss Physcomitrella patens is an evolutionarily basal model system suitable for the analysis of plant defence responses activated after pathogen assault. Upon infection with the necrotroph Botrytis cinerea, several defence mechanisms are induced in P. patens, including the fortification of the plant cell wall by the incorporation of phenolic compounds and the induced expression of related genes. Botrytis cinerea infection also activates the accumulation of reactive oxygen species and cell death with hallmarks of programmed cell death in moss tissues. Salicylic acid (SA) levels also increase after fungal infection, and treatment with SA enhances transcript accumulation of the defence gene phenylalanine ammonia-lyase (PAL) in P. patens colonies. The expression levels of the genes involved in 12-oxo-phytodienoic acid (OPDA) synthesis, including lipoxygenase (LOX) and allene oxide synthase (AOS), increase in P. patens gametophytes after pathogen assault, together with a rise in free linolenic acid and OPDA concentrations. However, jasmonic acid (JA) could not be detected in healthy or infected tissues of this plant. Our results suggest that, although conserved defence signals, such as SA and OPDA, are synthesized and are probably involved in the defence response of P. patens against B. cinerea infection, JA production appears to be missing. Interestingly, P. patens responds to OPDA and methyl jasmonate by reducing moss colony growth and rhizoid length, suggesting that jasmonate perception is present in mosses. Thus, P. patens can provide clues with regard to the evolution of different defence pathways in plants, including signalling and perception of OPDA and jasmonates in nonflowering and flowering plants. © 2012 THE AUTHORS. MOLECULAR PLANT PATHOLOGY © 2012 BSPP AND BLACKWELL PUBLISHING LTD.

  7. The transcription factor ABI4 Is required for the ascorbic acid-dependent regulation of growth and regulation of jasmonate-dependent defense signaling pathways in Arabidopsis.

    Kerchev, Pavel I; Pellny, Till K; Vivancos, Pedro Diaz; Kiddle, Guy; Hedden, Peter; Driscoll, Simon; Vanacker, Hélène; Verrier, Paul; Hancock, Robert D; Foyer, Christine H

    2011-09-01

    Cellular redox homeostasis is a hub for signal integration. Interactions between redox metabolism and the ABSCISIC ACID-INSENSITIVE-4 (ABI4) transcription factor were characterized in the Arabidopsis thaliana vitamin c defective1 (vtc1) and vtc2 mutants, which are defective in ascorbic acid synthesis and show a slow growth phenotype together with enhanced abscisic acid (ABA) levels relative to the wild type (Columbia-0). The 75% decrease in the leaf ascorbate pool in the vtc2 mutants was not sufficient to adversely affect GA metabolism. The transcriptome signatures of the abi4, vtc1, and vtc2 mutants showed significant overlap, with a large number of transcription factors or signaling components similarly repressed or induced. Moreover, lincomycin-dependent changes in LIGHT HARVESTING CHLOROPHYLL A/B BINDING PROTEIN 1.1 expression were comparable in these mutants, suggesting overlapping participation in chloroplast to nucleus signaling. The slow growth phenotype of vtc2 was absent in the abi4 vtc2 double mutant, as was the sugar-insensitive phenotype of the abi4 mutant. Octadecanoid derivative-responsive AP2/ERF-domain transcription factor 47 (ORA47) and AP3 (an ABI5 binding factor) transcripts were enhanced in vtc2 but repressed in abi4 vtc2, suggesting that ABI4 and ascorbate modulate growth and defense gene expression through jasmonate signaling. We conclude that low ascorbate triggers ABA- and jasmonate-dependent signaling pathways that together regulate growth through ABI4. Moreover, cellular redox homeostasis exerts a strong influence on sugar-dependent growth regulation.

  8. Analysis of two potential long-distance signaling molecules, LjCLE-RS1/2 and jasmonic acid, in a hypernodulating mutant too much love.

    Magori, Shimpei; Kawaguchi, Masayoshi

    2010-04-01

    Legume plants tightly control the number and development of root nodules. This is partly regulated by a long-distance signaling known as auto-regulation of nodulation (AON). AON signaling involves at least two potential long-distance signals: root-derived signal and shoot-derived signal. However, their molecular characteristics and the mode of action remain unclear. In our recent study, we isolated a novel Lotus japonicus hypernodulating mutant too much love (tml). Based on several grafting experiments, we concluded that its causative gene TML functions as a receptor of the shoot-derived signal. This finding prompted us to ask how the candidates of the long-distance signal molecules, LjCLE-RS1/2 and jasmonic acid (JA), are affected in tml mutants. Expression analysis revealed that rapid induction of LjCLE-RS1/2 upon rhizobial inoculation is still intact in tml, supporting that TML plays a role in reception of the shoot-derived signal but not in generation of the root-derived signal. Furthermore, physiological analysis showed that JA, a candidate of the shoot-derived signal, can suppress tml hypernodulation. Therefore, contrary to the previous report, JA might not be a component of AON signaling.

  9. Airborne signals from Trichoderma fungi stimulate iron uptake responses in roots resulting in priming of jasmonic acid-dependent defences in shoots of Arabidopsis thaliana and Solanum lycopersicum.

    Martínez-Medina, Ainhoa; Van Wees, Saskia C M; Pieterse, Corné M J

    2017-11-01

    Root colonization by Trichoderma fungi can trigger induced systemic resistance (ISR). In Arabidopsis, Trichoderma-ISR relies on the transcription factor MYB72, which plays a dual role in the onset of ISR and the activation of Fe uptake responses. Volatile compounds (VCs) from rhizobacteria are important elicitors of MYB72 in Arabidopsis roots. Here, we investigated the mode of action of VCs from Trichoderma fungi in the onset of ISR and Fe uptake responses. VCs from Trichoderma asperellum and Trichoderma harzianum were applied in an in vitro split-plate system with Arabidopsis or tomato seedlings. Locally, Trichoderma-VCs triggered MYB72 expression and molecular, physiological and morphological Fe uptake mechanisms in Arabidopsis roots. In leaves, Trichoderma-VCs primed jasmonic acid-dependent defences, leading to an enhanced resistance against Botrytis cinerea. By using Arabidopsis micrografts of VCs-exposed rootstocks and non-exposed scions, we demonstrated that perception of Trichoderma-VCs by the roots leads to a systemic signal that primes shoots for enhanced defences. Trichoderma-VCs also elicited Fe deficiency responses and shoot immunity in tomato, suggesting that this phenomenon is expressed in different plant species. Our results indicate that Trichoderma-VCs trigger locally a readjustment of Fe homeostasis in roots, which links to systemic elicitation of ISR by priming of jasmonic acid-dependent defences. © 2017 John Wiley & Sons Ltd.

  10. Jasmonate signaling is activated in the very early stages of iron deficiency responses in rice roots.

    Kobayashi, Takanori; Itai, Reiko Nakanishi; Senoura, Takeshi; Oikawa, Takaya; Ishimaru, Yasuhiro; Ueda, Minoru; Nakanishi, Hiromi; Nishizawa, Naoko K

    2016-07-01

    Under low iron availability, plants induce the expression of various genes involved in iron uptake and translocation at the transcriptional level. This iron deficiency response is affected by various plant hormones, but the roles of jasmonates in this response are not well-known. We investigated the involvement of jasmonates in rice iron deficiency responses. High rates of jasmonate-inducible genes were induced during the very early stages of iron deficiency treatment in rice roots. Many jasmonate-inducible genes were also negatively regulated by the ubiquitin ligases OsHRZ1 and OsHRZ2 and positively regulated by the transcription factor IDEF1. Ten out of 35 genes involved in jasmonate biosynthesis and signaling were rapidly induced at 3 h of iron deficiency treatment, and this induction preceded that of known iron deficiency-inducible genes involved in iron uptake and translocation. Twelve genes involved in jasmonate biosynthesis and signaling were also upregulated in HRZ-knockdown roots. Endogenous concentrations of jasmonic acid and jasmonoyl isoleucine tended to be rapidly increased in roots in response to iron deficiency treatment, whereas these concentrations were higher in HRZ-knockdown roots under iron-sufficient conditions. Analysis of the jasmonate-deficient cpm2 mutant revealed that jasmonates repress the expression of many iron deficiency-inducible genes involved in iron uptake and translocation under iron sufficiency, but this repression is partly canceled under an early stage of iron deficiency. These results indicate that jasmonate signaling is activated during the very early stages of iron deficiency, which is partly regulated by IDEF1 and OsHRZs.

  11. Jasmonates: biosynthesis, perception, signal transduction and action in plant stress response, growth and development. An update to the 2007 review in Annals of Botany.

    Wasternack, C; Hause, B

    2013-06-01

    Jasmonates are important regulators in plant responses to biotic and abiotic stresses as well as in development. Synthesized from lipid-constituents, the initially formed jasmonic acid is converted to different metabolites including the conjugate with isoleucine. Important new components of jasmonate signalling including its receptor were identified, providing deeper insight into the role of jasmonate signalling pathways in stress responses and development. The present review is an update of the review on jasmonates published in this journal in 2007. New data of the last five years are described with emphasis on metabolites of jasmonates, on jasmonate perception and signalling, on cross-talk to other plant hormones and on jasmonate signalling in response to herbivores and pathogens, in symbiotic interactions, in flower development, in root growth and in light perception. The last few years have seen breakthroughs in the identification of JASMONATE ZIM DOMAIN (JAZ) proteins and their interactors such as transcription factors and co-repressors, and the crystallization of the jasmonate receptor as well as of the enzyme conjugating jasmonate to amino acids. Now, the complex nature of networks of jasmonate signalling in stress responses and development including hormone cross-talk can be addressed.

  12. Aboveground Whitefly Infestation Modulates Transcriptional Levels of Anthocyanin Biosynthesis and Jasmonic Acid Signaling-Related Genes and Augments the Cope with Drought Stress of Maize.

    Yong-Soon Park

    Full Text Available Up to now, the potential underlying molecular mechanisms by which maize (Zea mays L. plants elicit defense responses by infestation with a phloem feeding insect whitefly [Bemisia tabaci (Genn.] have been barely elucidated against (abiotic stresses. To fill this gap of current knowledge maize plants were infested with whitefly and these plants were subsequently assessed the levels of water loss. To understand the mode of action, plant hormone contents and the stress-related mRNA expression were evaluated. Whitefly-infested maize plants did not display any significant phenotypic differences in above-ground tissues (infested site compared with controls. By contrast, root (systemic tissue biomass was increased by 2-fold by whitefly infestation. The levels of endogenous indole-3-acetic acid (IAA, jasmonic acid (JA, and hydrogen peroxide (H2O2 were significantly higher in whitefly-infested plants. The biosynthetic or signaling-related genes for JA and anthocyanins were highly up-regulated. Additionally, we found that healthier plants were obtained in whitefly-infested plants under drought conditions. The weight of whitefly-infested plants was approximately 20% higher than that of control plants at 14 d of drought treatment. The drought tolerance-related genes, ZmbZIP72, ZmSNAC1, and ZmABA1, were highly expressed in the whitefly-infected plants. Collectively, our results suggest that IAA/JA-derived maize physiological changes and correlation of H2O2 production and water loss are modulated by above-ground whitefly infestation in maize plants.

  13. Jasmonates: Biosynthesis, metabolism, and signaling by proteins activating and repressing transcription

    Wasternack, Claus; Song, S.

    2017-01-01

    Roč. 68, č. 6 (2017), s. 1303-1321 ISSN 0022-0957 Institutional support: RVO:61389030 Keywords : Activators * Amino acid conjugates * Biosynthesis * Jasmonic acid * Metabolism * Perception * Repressors * SCFJAZ co-receptor complex COI1 * Signaling Subject RIV: EI - Biotechnology ; Bionics OBOR OECD: Plant sciences, botany Impact factor: 5.830, year: 2016

  14. Arabidopsis GLUTATHIONE REDUCTASE1 plays a crucial role in leaf responses to intracellular hydrogen peroxide and in ensuring appropriate gene expression through both salicylic acid and jasmonic acid signaling pathways.

    Mhamdi, Amna; Hager, Jutta; Chaouch, Sejir; Queval, Guillaume; Han, Yi; Taconnat, Ludivine; Saindrenan, Patrick; Gouia, Houda; Issakidis-Bourguet, Emmanuelle; Renou, Jean-Pierre; Noctor, Graham

    2010-07-01

    Glutathione is a major cellular thiol that is maintained in the reduced state by glutathione reductase (GR), which is encoded by two genes in Arabidopsis (Arabidopsis thaliana; GR1 and GR2). This study addressed the role of GR1 in hydrogen peroxide (H(2)O(2)) responses through a combined genetic, transcriptomic, and redox profiling approach. To identify the potential role of changes in glutathione status in H(2)O(2) signaling, gr1 mutants, which show a constitutive increase in oxidized glutathione (GSSG), were compared with a catalase-deficient background (cat2), in which GSSG accumulation is conditionally driven by H(2)O(2). Parallel transcriptomics analysis of gr1 and cat2 identified overlapping gene expression profiles that in both lines were dependent on growth daylength. Overlapping genes included phytohormone-associated genes, in particular implicating glutathione oxidation state in the regulation of jasmonic acid signaling. Direct analysis of H(2)O(2)-glutathione interactions in cat2 gr1 double mutants established that GR1-dependent glutathione status is required for multiple responses to increased H(2)O(2) availability, including limitation of lesion formation, accumulation of salicylic acid, induction of pathogenesis-related genes, and signaling through jasmonic acid pathways. Modulation of these responses in cat2 gr1 was linked to dramatic GSSG accumulation and modified expression of specific glutaredoxins and glutathione S-transferases, but there is little or no evidence of generalized oxidative stress or changes in thioredoxin-associated gene expression. We conclude that GR1 plays a crucial role in daylength-dependent redox signaling and that this function cannot be replaced by the second Arabidopsis GR gene or by thiol systems such as the thioredoxin system.

  15. Induced Production of 1-Methoxy-indol-3-ylmethyl Glucosinolate by Jasmonic Acid and Methyl Jasmonate in Sprouts and Leaves of Pak Choi (Brassica rapa ssp. chinensis

    Hansruedi Glatt

    2013-07-01

    Full Text Available Pak choi plants (Brassica rapa ssp. chinensis were treated with different signaling molecules methyl jasmonate, jasmonic acid, linolenic acid, and methyl salicylate and were analyzed for specific changes in their glucosinolate profile. Glucosinolate levels were quantified using HPLC-DAD-UV, with focus on induction of indole glucosinolates and special emphasis on 1-methoxy-indol-3-ylmethyl glucosinolate. Furthermore, the effects of the different signaling molecules on indole glucosinolate accumulation were analyzed on the level of gene expression using semi-quantitative realtime RT-PCR of selected genes. The treatments with signaling molecules were performed on sprouts and mature leaves to determine ontogenetic differences in glucosinolate accumulation and related gene expression. The highest increase of indole glucosinolate levels, with considerable enhancement of the 1-methoxy-indol-3-ylmethyl glucosinolate content, was achieved with treatments of sprouts and mature leaves with methyl jasmonate and jasmonic acid. This increase was accompanied by increased expression of genes putatively involved in the indole glucosinolate biosynthetic pathway. The high levels of indole glucosinolates enabled the plant to preferentially produce the respective breakdown products after tissue damage. Thus, pak choi plants treated with methyl jasmonate or jasmonic acid, are a valuable tool to analyze the specific protection functions of 1-methoxy-indole-3-carbinole in the plants defense strategy in the future.

  16. The platelet-activating factor acetylhydrolase gene derived from Trichoderma harzianum induces maize resistance to Curvularia lunata through the jasmonic acid signaling pathway.

    Yu, Chuanjin; Fan, Lili; Gao, Jinxin; Wang, Meng; Wu, Qiong; Tang, Jun; Li, Yaqian; Chen, Jie

    2015-01-01

    Platelet-activating factor acetylhydrolase (PAF-AH) derived from Trichoderma harzianum was upregulated by the interaction of T. harzianum with maize roots or the foliar pathogen Curvularia lunata. PAF-AH was associated with chitinase and cellulase expressions, but especially with chitinase, because its activity in the KO40 transformant (PAF-AH disruption transformant) was lower, compared with the wild-type strain T28. The result demonstrated that the colonization of maize roots by T. harzianum induced systemic protection of leaves inoculated with C. lunata. Such protection was associated with the expression of inducible jasmonic acid pathway-related genes. Moreover, the data from liquid chromatography-mass spectrometry confirmed that the concentration of jasmonic acid in maize leaves was associated with the expression level of defense-related genes, suggesting that PAF-AH induced resistance to the foliar pathogen. Our findings showed that PAF-AH had an important function in inducing systemic resistance to maize leaf spot pathogen.

  17. Jasmonic acid and salicylic acid activate a common defense system in rice.

    Tamaoki, Daisuke; Seo, Shigemi; Yamada, Shoko; Kano, Akihito; Miyamoto, Ayumi; Shishido, Hodaka; Miyoshi, Seika; Taniguchi, Shiduku; Akimitsu, Kazuya; Gomi, Kenji

    2013-06-01

    Jasmonic acid (JA) and salicylic acid (SA) play important roles in plant defense systems. JA and SA signaling pathways interact antagonistically in dicotyledonous plants, but, the status of crosstalk between JA and SA signaling is unknown in monocots. Our rice microarray analysis showed that more than half of the genes upregulated by the SA analog BTH are also upregulated by JA, suggesting that a major portion of the SA-upregulated genes are regulated by JA-dependent signaling in rice. A common defense system that is activated by both JA and SA is thus proposed which plays an important role in pathogen defense responses in rice.

  18. Integrating nitric oxide into salicylic acid and jasmonic acid/ethylene plant defense pathways

    Mur, Luis A J; Prats, Elena; Pierre, Sandra

    2013-01-01

    to be tailored to particular biotic stresses. Nitric oxide (NO) has emerged as a major signal influencing resistance mediated by both signalling pathways but no attempt has been made to integrate NO into established SA/JA/ET interactions. NO has been shown to act as an inducer or suppressor of signalling along......Plant defence against pests and pathogens is known to be conferred by either salicylic acid (SA) or jasmonic acid (JA)/ethylene (ET) pathways, depending on infection or herbivore-grazing strategy. It is well attested that SA and JA/ET pathways are mutually antagonistic allowing defence responses...

  19. Lipoxygenase in Caragana jubata responds to low temperature, abscisic acid, methyl jasmonate and salicylic acid.

    Bhardwaj, Pardeep Kumar; Kaur, Jagdeep; Sobti, Ranbir Chander; Ahuja, Paramvir Singh; Kumar, Sanjay

    2011-09-01

    Lipoxygenase (LOX) catalyses oxygenation of free polyunsaturated fatty acids into oxylipins, and is a critical enzyme of the jasmonate signaling pathway. LOX has been shown to be associated with biotic and abiotic stress responses in diverse plant species, though limited data is available with respect to low temperature and the associated cues. Using rapid amplification of cDNA ends, a full-length cDNA (CjLOX) encoding lipoxygenase was cloned from apical buds of Caragana jubata, a temperate plant species that grows under extreme cold. The cDNA obtained was 2952bp long consisting of an open reading frame of 2610bp encoding 869 amino acids protein. Multiple alignment of the deduced amino acid sequence with those of other plants demonstrated putative LH2/ PLAT domain, lipoxygenase iron binding catalytic domain and lipoxygenase_2 signature sequences. CjLOX exhibited up- and down-regulation of gene expression pattern in response to low temperature (LT), abscisic acid (ABA), methyl jasmonate (MJ) and salicylic acid (SA). Among all the treatments, a strong up-regulation was observed in response to MJ. Data suggests an important role of jasmonate signaling pathway in response to LT in C. jubata. Copyright © 2011 Elsevier B.V. All rights reserved.

  20. Jasmonic acid/methyl jasmonate accumulate in wounded soybean hypocotyls and modulate wound gene expression.

    Creelman, R A; Tierney, M L; Mullet, J E

    1992-06-01

    Jasmonic acid (JA) and its methyl ester, methyl jasmonate (MeJA), are plant lipid derivatives that resemble mammalian eicosanoids in structure and biosynthesis. These compounds are proposed to play a role in plant wound and pathogen responses. Here we report the quantitative determination of JA/MeJA in planta by a procedure based on the use of [13C,2H3]MeJA as an internal standard. Wounded soybean (Glycine max [L] Merr. cv. Williams) stems rapidly accumulated MeJA and JA. Addition of MeJA to soybean suspension cultures also increased mRNA levels for three wound-responsive genes (chalcone synthase, vegetative storage protein, and proline-rich cell wall protein) suggesting a role for MeJA/JA in the mediation of several changes in gene expression associated with the plants' response to wounding.

  1. GmCYP82A3, a Soybean Cytochrome P450 Family Gene Involved in the Jasmonic Acid and Ethylene Signaling Pathway, Enhances Plant Resistance to Biotic and Abiotic Stresses.

    Qiang Yan

    Full Text Available The cytochrome P450 monooxygenases (P450s represent a large and important enzyme superfamily in plants. They catalyze numerous monooxygenation/hydroxylation reactions in biochemical pathways, P450s are involved in a variety of metabolic pathways and participate in the homeostasis of phytohormones. The CYP82 family genes specifically reside in dicots and are usually induced by distinct environmental stresses. However, their functions are largely unknown, especially in soybean (Glycine max L.. Here, we report the function of GmCYP82A3, a gene from soybean CYP82 family. Its expression was induced by Phytophthora sojae infection, salinity and drought stresses, and treatment with methyl jasmonate (MeJA or ethephon (ETH. Its expression levels were consistently high in resistant cultivars. Transgenic Nicotiana benthamiana plants overexpressing GmCYP82A3 exhibited strong resistance to Botrytis cinerea and Phytophthora parasitica, and enhanced tolerance to salinity and drought stresses. Furthermore, transgenic plants were less sensitive to jasmonic acid (JA, and the enhanced resistance was accompanied with increased expression of the JA/ET signaling pathway-related genes.

  2. Optimized Jasmonic Acid Production by Lasiodiplodia theobromae Reveals Formation of Valuable Plant Secondary Metabolites.

    Felipe Eng

    Full Text Available Jasmonic acid is a plant hormone that can be produced by the fungus Lasiodiplodia theobromae via submerged fermentation. From a biotechnological perspective jasmonic acid is a valuable feedstock as its derivatives serve as important ingredients in different cosmetic products and in the future it may be used for pharmaceutical applications. The objective of this work was to improve the production of jasmonic acid by L. theobromae strain 2334. We observed that jasmonic acid formation is dependent on the culture volume. Moreover, cultures grown in medium containing potassium nitrate as nitrogen source produced higher amounts of jasmonic acid than analogous cultures supplemented with ammonium nitrate. When cultivated under optimal conditions for jasmonic acid production, L. theobromae secreted several secondary metabolites known from plants into the medium. Among those we found 3-oxo-2-(pent-2-enyl-cyclopentane-1-butanoic acid (OPC-4 and hydroxy-jasmonic acid derivatives, respectively, suggesting that fungal jasmonate metabolism may involve similar reaction steps as that of plants. To characterize fungal growth and jasmonic acid-formation, we established a mathematical model describing both processes. This model may form the basis of industrial upscaling attempts. Importantly, it showed that jasmonic acid-formation is not associated to fungal growth. Therefore, this finding suggests that jasmonic acid, despite its enormous amount being produced upon fungal development, serves merely as secondary metabolite.

  3. ORA47 (octadecanoid-responsive AP2/ERF-domain transcription factor 47) regulates jasmonic acid and abscisic acid biosynthesis and signaling through binding to a novel cis-element.

    Chen, Hsing-Yu; Hsieh, En-Jung; Cheng, Mei-Chun; Chen, Chien-Yu; Hwang, Shih-Ying; Lin, Tsan-Piao

    2016-07-01

    ORA47 (octadecanoid-responsive AP2/ERF-domain transcription factor 47) of Arabidopsis thaliana is an AP2/ERF domain transcription factor that regulates jasmonate (JA) biosynthesis and is induced by methyl JA treatment. The regulatory mechanism of ORA47 remains unclear. ORA47 is shown to bind to the cis-element (NC/GT)CGNCCA, which is referred to as the O-box, in the promoter of ABI2. We proposed that ORA47 acts as a connection between ABA INSENSITIVE1 (ABI1) and ABI2 and mediates an ABI1-ORA47-ABI2 positive feedback loop. PORA47:ORA47-GFP transgenic plants were used in a chromatin immunoprecipitation (ChIP) assay to show that ORA47 participates in the biosynthesis and/or signaling pathways of nine phytohormones. Specifically, many abscisic acid (ABA) and JA biosynthesis and signaling genes were direct targets of ORA47 under stress conditions. The JA content of the P35S:ORA47-GR lines was highly induced under wounding and moderately induced under water stress relative to that of the wild-type plants. The wounding treatment moderately increased ABA accumulation in the transgenic lines, whereas the water stress treatment repressed the ABA content. ORA47 is proposed to play a role in the biosynthesis of JA and ABA and in regulating the biosynthesis and/or signaling of a suite of phytohormone genes when plants are subjected to wounding and water stress. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

  4. Interactive Effects of Jasmonic Acid, Salicylic Acid, and Gibberellin on Induction of Trichomes in Arabidopsis1

    Traw, M. Brian; Bergelson, Joy

    2003-01-01

    Leaf trichomes protect plants from attack by insect herbivores and are often induced following damage. Hormonal regulation of this plant induction response has not been previously studied. In a series of experiments, we addressed the effects of artificial damage, jasmonic acid, salicylic acid, and gibberellin on induction of trichomes in Arabidopsis. Artificial damage and jasmonic acid caused significant increases in trichome production of leaves. The jar1-1 mutant exhibited normal trichome induction following treatment with jasmonic acid, suggesting that adenylation of jasmonic acid is not necessary. Salicylic acid had a negative effect on trichome production and consistently reduced the effect of jasmonic acid, suggesting negative cross-talk between the jasmonate and salicylate-dependent defense pathways. Interestingly, the effect of salicylic acid persisted in the nim1-1 mutant, suggesting that the Npr1/Nim1 gene is not downstream of salicylic acid in the negative regulation of trichome production. Last, we found that gibberellin and jasmonic acid had a synergistic effect on the induction of trichomes, suggesting important interactions between these two compounds. PMID:14551332

  5. A jasmonate ZIM-domain protein NaJAZd regulates floral jasmonic acid levels and counteracts flower abscission in Nicotiana attenuata plants.

    Youngjoo Oh

    Full Text Available Jasmonic acid is an important regulator of plant growth, development and defense. The jasmonate-ZIM domain (JAZ proteins are key regulators in jasmonate signaling ubiquitously present in flowering plants but their functional annotation remains largely incomplete. Recently, we identified 12 putative JAZ proteins in native tobacco, Nicotiana attenuata, and initiated systematic functional characterization of these proteins by reverse genetic approaches. In this report, Nicotiana attenuata plants silenced in the expression of NaJAZd (irJAZd by RNA interference were used to characterize NaJAZd function. Although NaJAZd transcripts were strongly and transiently up-regulated in the rosette leaves by simulated herbivory treatment, we did not observe strong defense-related phenotypes, such as altered herbivore performance or the constitutive accumulation of defense-related secondary metabolites in irJAZd plants compared to wild type plants, both in the glasshouse and the native habitat of Nicotiana attenuata in the Great Basin Desert, Utah, USA. Interestingly, irJAZd plants produced fewer seed capsules than did wild type plants as a result of increased flower abscission in later stages of flower development. The early- and mid-developmental stages of irJAZd flowers had reduced levels of jasmonic acid and jasmonoyl-L-isoleucine, while fully open flowers had normal levels, but these were impaired in NaMYB305 transcript accumulations. Previously, NaMYB305-silenced plants were shown to have strong flower abscission phenotypes and contained lower NECTARIN 1 transcript levels, phenotypes which are copied in irJAZd plants. We propose that the NaJAZd protein is required to counteract flower abscission, possibly by regulating jasmonic acid and jasmonoyl-L-isoleucine levels and/or expression of NaMYB305 gene in Nicotiana attenuata flowers. This novel insight into the function of JAZ proteins in flower and seed development highlights the diversity of functions

  6. Rpi-blb2-Mediated Hypersensitive Cell Death Caused by Phytophthora infestans AVRblb2 Requires SGT1, but not EDS1, NDR1, Salicylic Acid-, Jasmonic Acid-, or Ethylene-Mediated Signaling

    Sang-Keun Oh

    2014-09-01

    Full Text Available Potato Rpi-blb2 encodes a protein with a coiled-coil-nucleotide binding site and leucine-rich repeat (CC-NBS-LRR motif that recognizes the Phytophthora infestans AVRblb2 effector and triggers hypersensitive cell death (HCD. To better understand the components required for Rpi-blb2-mediated HCD in plants, we used virus-induced gene silencing to repress candidate genes in Rpi-blb2-transgenic Nicotiana benthamiana plants and assayed the plants for AVRblb2 effector. Rpi-blb2 triggers HCD through NbSGT1-mediated pathways, but not NbEDS1- or NbNDR1-mediated pathways. In addition, the role of salicylic acid (SA, jasmonic acid (JA, and ethylene (ET in Rpi-blb2-mediated HCD were analyzed by monitoring of the responses of NbICS1-, NbCOI1-, or NbEIN2-silenced or Rpi-blb2::NahG-transgenic plants. Rpi-blb2-mediated HCD in response to AVRblb2 was not associated with SA accumulation. Thus, SA affects Rpi-blb2-mediated resistance against P. infestans, but not Rpi-blb2-mediated HCD in response to AVRblb2. Additionally, JA and ET signaling were not required for Rpi-blb2-mediated HCD in N. benthamiana. Taken together, these findings suggest that NbSGT1 is a unique positive regulator of Rpi-blb2-mediated HCD in response to AVRblb2, but EDS1, NDR1, SA, JA, and ET are not required.

  7. Low oleic acid-derived repression of jasmonic acid-inducible defense responses requires the WRKY50 and WRKY51 proteins

    Signaling induced upon a reduction in oleic acid (18:1) levels simultaneously up-regulates salicylic acid (SA)-mediated responses and inhibits jasmonic acid (JA)-inducible defenses, resulting in enhanced resistance to biotrophs but increased susceptibility to necrotrophs. SA and the signaling compon...

  8. Ethylene and jasmonic acid act as negative modulators during mutualistic symbiosis between Laccaria bicolor and Populus roots.

    Plett, Jonathan M; Khachane, Amit; Ouassou, Malika; Sundberg, Björn; Kohler, Annegret; Martin, Francis

    2014-04-01

    The plant hormones ethylene, jasmonic acid and salicylic acid have interconnecting roles during the response of plant tissues to mutualistic and pathogenic symbionts. We used morphological studies of transgenic- or hormone-treated Populus roots as well as whole-genome oligoarrays to examine how these hormones affect root colonization by the mutualistic ectomycorrhizal fungus Laccaria bicolor S238N. We found that genes regulated by ethylene, jasmonic acid and salicylic acid were regulated in the late stages of the interaction between L. bicolor and poplar. Both ethylene and jasmonic acid treatments were found to impede fungal colonization of roots, and this effect was correlated to an increase in the expression of certain transcription factors (e.g. ETHYLENE RESPONSE FACTOR1) and a decrease in the expression of genes associated with microbial perception and cell wall modification. Further, we found that ethylene and jasmonic acid showed extensive transcriptional cross-talk, cross-talk that was opposed by salicylic acid signaling. We conclude that ethylene and jasmonic acid pathways are induced late in the colonization of root tissues in order to limit fungal growth within roots. This induction is probably an adaptive response by the plant such that its growth and vigor are not compromised by the fungus. © 2013 The Authors New Phytologist © 2013 New Phytologist Trust.

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

    Vos, I.A.; Verhage, A.; Schuurink, R.C.; Watt, L.G.; Pieterse, C.M.J.; van Wees, S.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.

  10. Induced Jasmonate Signaling Leads to Contrasting Effects on Root Damage and Herbivore Performance1

    Lu, Jing; Robert, Christelle Aurélie Maud; Riemann, Michael; Cosme, Marco; Mène-Saffrané, Laurent; Massana, Josep; Stout, Michael Joseph; Lou, Yonggen; Gershenzon, Jonathan; Erb, Matthias

    2015-01-01

    Induced defenses play a key role in plant resistance against leaf feeders. However, very little is known about the signals that are involved in defending plants against root feeders and how they are influenced by abiotic factors. We investigated these aspects for the interaction between rice (Oryza sativa) and two root-feeding insects: the generalist cucumber beetle (Diabrotica balteata) and the more specialized rice water weevil (Lissorhoptrus oryzophilus). Rice plants responded to root attack by increasing the production of jasmonic acid (JA) and abscisic acid, whereas in contrast to in herbivore-attacked leaves, salicylic acid and ethylene levels remained unchanged. The JA response was decoupled from flooding and remained constant over different soil moisture levels. Exogenous application of methyl JA to the roots markedly decreased the performance of both root herbivores, whereas abscisic acid and the ethylene precursor 1-aminocyclopropane-1-carboxylic acid did not have any effect. JA-deficient antisense 13-lipoxygenase (asLOX) and mutant allene oxide cyclase hebiba plants lost more root biomass under attack from both root herbivores. Surprisingly, herbivore weight gain was decreased markedly in asLOX but not hebiba mutant plants, despite the higher root biomass removal. This effect was correlated with a herbivore-induced reduction of sucrose pools in asLOX roots. Taken together, our experiments show that jasmonates are induced signals that protect rice roots from herbivores under varying abiotic conditions and that boosting jasmonate responses can strongly enhance rice resistance against root pests. Furthermore, we show that a rice 13-lipoxygenase regulates root primary metabolites and specifically improves root herbivore growth. PMID:25627217

  11. Altered cultivar resistance of kimchi cabbage seedlings mediated by salicylic Acid, jasmonic Acid and ethylene.

    Lee, Young Hee; Kim, Sang Hee; Yun, Byung-Wook; Hong, Jeum Kyu

    2014-09-01

    Two cultivars Buram-3-ho (susceptible) and CR-Hagwang (moderate resistant) of kimchi cabbage seedlings showed differential defense responses to anthracnose (Colletotrichum higginsianum), black spot (Alternaria brassicicola) and black rot (Xanthomonas campestris pv. campestris, Xcc) diseases in our previous study. Defense-related hormones salicylic acid (SA), jasmonic acid (JA) and ethylene led to different transcriptional regulation of pathogenesis-related (PR) gene expression in both cultivars. In this study, exogenous application of SA suppressed basal defenses to C. higginsianum in the 1st leaves of the susceptible cultivar and cultivar resistance of the 2nd leaves of the resistant cultivar. SA also enhanced susceptibility of the susceptible cultivar to A. brassicicola. By contrast, SA elevated disease resistance to Xcc in the resistant cultivar, but not in the susceptible cultivar. Methyl jasmonate (MJ) treatment did not affect the disease resistance to C. higginsianum and Xcc in either cultivar, but it compromised the disease resistance to A. brassicicola in the resistant cultivar. Treatment with 1-aminocyclopropane-1-carboxylic acid (ACC) ethylene precursor did not change resistance of the either cultivar to C. higginsianum and Xcc. Effect of ACC pretreatment on the resistance to A. brassicicola was not distinguished between susceptible and resistant cultivars, because cultivar resistance of the resistant cultivar was lost by prolonged moist dark conditions. Taken together, exogenously applied SA, JA and ethylene altered defense signaling crosstalk to three diseases of anthracnose, black spot and black rot in a cultivar-dependent manner.

  12. Altered Cultivar Resistance of Kimchi Cabbage Seedlings Mediated by Salicylic Acid, Jasmonic Acid and Ethylene

    Young Hee Lee

    2014-09-01

    Full Text Available Two cultivars Buram-3-ho (susceptible and CR-Hagwang (moderate resistant of kimchi cabbage seedlings showed differential defense responses to anthracnose (Colletotrichum higginsianum, black spot (Alternaria brassicicola and black rot (Xanthomonas campestris pv. campestris, Xcc diseases in our previous study. Defense-related hormones salicylic acid (SA, jasmonic acid (JA and ethylene led to different transcriptional regulation of pathogenesis-related (PR gene expression in both cultivars. In this study, exogenous application of SA suppressed basal defenses to C. higginsianum in the 1st leaves of the susceptible cultivar and cultivar resistance of the 2nd leaves of the resistant cultivar. SA also enhanced susceptibility of the susceptible cultivar to A. brassicicola. By contrast, SA elevated disease resistance to Xcc in the resistant cultivar, but not in the susceptible cultivar. Methyl jasmonate (MJ treatment did not affect the disease resistance to C. higginsianum and Xcc in either cultivar, but it compromised the disease resistance to A. brassicicola in the resistant cultivar. Treatment with 1-aminocyclopropane-1-carboxylic acid (ACC ethylene precursor did not change resistance of the either cultivar to C. higginsianum and Xcc. Effect of ACC pretreatment on the resistance to A. brassicicola was not distinguished between susceptible and resistant cultivars, because cultivar resistance of the resistant cultivar was lost by prolonged moist dark conditions. Taken together, exogenously applied SA, JA and ethylene altered defense signaling crosstalk to three diseases of anthracnose, black spot and black rot in a cultivar-dependent manner.

  13. Ectopic expression of Arabidopsis genes encoding salicylic acid- and jasmonic acid-related proteins confers partial resistance to soybean cyst nematode (Heterodera glycines) in transgenic soybean roots

    Background. Extensive studies using the model system Arabidopsis thaliana to elucidate plant defense signaling and pathway networks indicate that salicylic acid (SA) is the key hormone triggering the plant defense response against biotrophic and hemi-biotrophic pathogens, while jasmonic acid (JA) an...

  14. Assessing the Role of ETHYLENE RESPONSE FACTOR Transcriptional Repressors in Salicylic Acid-Mediated Suppression of Jasmonic Acid-Responsive Genes

    Caarls, Lotte; van der Does, Adriana; Hickman, Richard; Jansen, Wouter; van Verk, Marcel; Proietti, Silvia; Lorenzo, Oscar; Solano, Roberto; Pieterse, Corné M J; Van Wees, Saskia C M

    2017-01-01

    Salicylic acid (SA) and jasmonic acid (JA) cross-communicate in the plant immune signaling network to finely regulate induced defenses. In Arabidopsis, SA antagonizes many JA-responsive genes, partly by targeting the ETHYLENE RESPONSE FACTOR (ERF)-type transcriptional activator ORA59. Members of the

  15. Jasmonate signalling in Arabidopsis involves SGT1b-HSP70-HSP90 chaperone complexes.

    Zhang, Xue-Cheng; Millet, Yves A; Cheng, Zhenyu; Bush, Jenifer; Ausubel, Frederick M

    Plant hormones play pivotal roles in growth, development and stress responses. Although it is essential to our understanding of hormone signalling, how plants maintain a steady state level of hormone receptors is poorly understood. We show that mutation of the Arabidopsis thaliana co-chaperone SGT1b impairs responses to the plant hormones jasmonate, auxin and gibberellic acid, but not brassinolide and abscisic acid, and that SGT1b and its homologue SGT1a are involved in maintaining the steady state levels of the F-box proteins COI1 and TIR1, receptors for jasmonate and auxin, respectively. The association of SGT1b with COI1 is direct and is independent of the Arabidopsis SKP1 protein, ASK1. We further show that COI1 is a client protein of SGT1b-HSP70-HSP90 chaperone complexes and that the complexes function in hormone signalling by stabilizing the COI1 protein. This study extends the SGT1b-HSP90 client protein list and broadens the functional scope of SGT1b-HSP70-HSP90 chaperone complexes.

  16. A fungal endophyte helps plants to tolerate root herbivory through changes in gibberellin and jasmonate signaling.

    Cosme, Marco; Lu, Jing; Erb, Matthias; Stout, Michael Joseph; Franken, Philipp; Wurst, Susanne

    2016-08-01

    Plant-microbe mutualisms can improve plant defense, but the impact of root endophytes on below-ground herbivore interactions remains unknown. We investigated the effects of the root endophyte Piriformospora indica on interactions between rice (Oryza sativa) plants and its root herbivore rice water weevil (RWW; Lissorhoptrus oryzophilus), and how plant jasmonic acid (JA) and GA regulate this tripartite interaction. Glasshouse experiments with wild-type rice and coi1-18 and Eui1-OX mutants combined with nutrient, jasmonate and gene expression analyses were used to test: whether RWW adult herbivory above ground influences subsequent damage caused by larval herbivory below ground; whether P. indica protects plants against RWW; and whether GA and JA signaling mediate these interactions. The endophyte induced plant tolerance to root herbivory. RWW adults and larvae acted synergistically via JA signaling to reduce root growth, while endophyte-elicited GA biosynthesis suppressed the herbivore-induced JA in roots and recovered plant growth. Our study shows for the first time the impact of a root endophyte on plant defense against below-ground herbivores, adds to growing evidence that induced tolerance may be an important root defense, and implicates GA as a signal component of inducible plant tolerance against biotic stress. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

  17. Sink limitation induces the expression of multiple soybean vegetative lipoxygenase mRNAs while the endogenous jasmonic acid level remains low.

    Bunker, T W; Koetje, D S; Stephenson, L C; Creelman, R A; Mullet, J E; Grimes, H D

    1995-08-01

    The response of individual members of the lipoxygenase multigene family in soybeans to sink deprivation was analyzed. RNase protection assays indicated that a novel vegetative lipoxygenase gene, vlxC, and three other vegetative lipoxygenase mRNAs accumulated in mature leaves in response to a variety of sink limitations. These data suggest that several members of the lipoxygenase multigene family are involved in assimilate partitioning. The possible involvement of jasmonic acid as a signaling molecule regulating assimilate partitioning into the vegetative storage proteins and lipoxygenases was directly assessed by determining the endogenous level of jasmonic acid in leaves from plants with their pods removed. There was no rise in the level of endogenous jasmonic acid coincident with the strong increase in both vlxC and vegetative storage protein VspB transcripts in response to sink limitation. Thus, expression of the vegetative lipoxygenases and vegetative storage proteins is not regulated by jasmonic acid in sink-limited leaves.

  18. Integrating nitric oxide into salicylic acid and jasmonic acid/ ethylene plant defense pathways.

    Mur, Luis A J; Prats, Elena; Pierre, Sandra; Hall, Michael A; Hebelstrup, Kim H

    2013-01-01

    Plant defense against pests and pathogens is known to be conferred by either salicylic acid (SA) or jasmonic acid (JA)/ethylene (ET) pathways, depending on infection or herbivore-grazing strategy. It is well attested that SA and JA/ET pathways are mutually antagonistic allowing defense responses to be tailored to particular biotic stresses. Nitric oxide (NO) has emerged as a major signal influencing resistance mediated by both signaling pathways but no attempt has been made to integrate NO into established SA/JA/ET interactions. NO has been shown to act as an inducer or suppressor of signaling along each pathway. NO will initiate SA biosynthesis and nitrosylate key cysteines on TGA-class transcription factors to aid in the initiation of SA-dependent gene expression. Against this, S-nitrosylation of NONEXPRESSOR OF PATHOGENESIS-RELATED PROTEINS1 (NPR1) will promote the NPR1 oligomerization within the cytoplasm to reduce TGA activation. In JA biosynthesis, NO will initiate the expression of JA biosynthetic enzymes, presumably to over-come any antagonistic effects of SA on JA-mediated transcription. NO will also initiate the expression of ET biosynthetic genes but a suppressive role is also observed in the S-nitrosylation and inhibition of S-adenosylmethionine transferases which provides methyl groups for ET production. Based on these data a model for NO action is proposed but we have also highlighted the need to understand when and how inductive and suppressive steps are used.

  19. PAMP-induced defense responses in potato require both salicylic acid and jasmonic acid.

    Halim, Vincentius A; Altmann, Simone; Ellinger, Dorothea; Eschen-Lippold, Lennart; Miersch, Otto; Scheel, Dierk; Rosahl, Sabine

    2009-01-01

    To elucidate the molecular mechanisms underlying pathogen-associated molecular pattern (PAMP)-induced defense responses in potato (Solanum tuberosum), the role of the signaling compounds salicylic acid (SA) and jasmonic acid (JA) was analyzed. Pep-13, a PAMP from Phytophthora, induces the accumulation of SA, JA and hydrogen peroxide, as well as the activation of defense genes and hypersensitive-like cell death. We have previously shown that SA is required for Pep-13-induced defense responses. To assess the importance of JA, RNA interference constructs targeted at the JA biosynthetic genes, allene oxide cyclase and 12-oxophytodienoic acid reductase, were expressed in transgenic potato plants. In addition, expression of the F-box protein COI1 was reduced by RNA interference. Plants expressing the RNA interference constructs failed to accumulate the respective transcripts in response to wounding or Pep-13 treatment, neither did they contain significant amounts of JA after elicitation. In response to infiltration of Pep-13, the transgenic plants exhibited a highly reduced accumulation of reactive oxygen species as well as reduced hypersensitive cell death. The ability of the JA-deficient plants to accumulate SA suggests that SA accumulation is independent or upstream of JA accumulation. These data show that PAMP responses in potato require both SA and JA and that, in contrast to Arabidopsis, these compounds act in the same signal transduction pathway. Despite their inability to fully respond to PAMP treatment, the transgenic RNA interference plants are not altered in their basal defense against Phytophthora infestans.

  20. Exogenous application of the plant signalers methyl jasmonate and salicylic acid induces changes in volatile emissions from citrus foliage and influences the aggregation behavior of Asian citrus psyllid (Diaphorina citri, vector of Huanglongbing.

    Joseph M Patt

    Full Text Available Huanglongbing, also known as citrus greening, is a destructive disease that threatens citrus production worldwide. It is putatively caused by the phloem-limited bacterium Candidatus Liberibacter asiaticus (Las. Currently, the disease is untreatable and efforts focus on intensive insecticide use to control the vector, Asian citrus psyllid (Diaphorina citri. Emerging psyllid resistance to multiple insecticides has generated investigations into the use of exogenously applied signaling compounds to enhance citrus resistance to D. citri and Las. In the present study, we examined whether foliar applications of methyl jasmonate (MJ, a volatile signaling compound associated with the induced systemic resistance pathway, and salicylic acid, a constituent of the systemic acquired resistance pathway, would elicit the emission of defense-related volatiles in citrus foliage, and what effect this might have on the host-plant searching behavior of D. citri. Comparisons were made of volatiles emitted from growing shoots of uninfected and Las-infected 'Valencia' sweet orange (Citrus sinensis trees over two consecutive sampling days. A settling behavioral assay was used to compare psyllid attraction to MJ-treated vs. Tween-treated citrus sprigs. All three main effects, Las infection status, plant signaler application, and sampling day, influenced the proportions of individual volatile compounds emitted in different treatment groups. MJ- and SA-treated trees had higher emission rates than Tween-treated trees. Methyl salicylate (MeSA and β-caryophyllene were present in higher proportions in the volatiles collected from Las-infected + trees. On the other hand, Las-infected + MJ-treated trees emitted lower proportions of MeSA than did Las-infected + Tween-treated trees. Because MeSA is a key D. citri attractant, this result suggests that MJ application could suppress MeSA emission from Las-infected trees, an approach that could be used to discourage psyllid

  1. Exogenous application of the plant signalers methyl jasmonate and salicylic acid induces changes in volatile emissions from citrus foliage and influences the aggregation behavior of Asian citrus psyllid (Diaphorina citri), vector of Huanglongbing.

    Patt, Joseph M; Robbins, Paul S; Niedz, Randy; McCollum, Greg; Alessandro, Rocco

    2018-01-01

    Huanglongbing, also known as citrus greening, is a destructive disease that threatens citrus production worldwide. It is putatively caused by the phloem-limited bacterium Candidatus Liberibacter asiaticus (Las). Currently, the disease is untreatable and efforts focus on intensive insecticide use to control the vector, Asian citrus psyllid (Diaphorina citri). Emerging psyllid resistance to multiple insecticides has generated investigations into the use of exogenously applied signaling compounds to enhance citrus resistance to D. citri and Las. In the present study, we examined whether foliar applications of methyl jasmonate (MJ), a volatile signaling compound associated with the induced systemic resistance pathway, and salicylic acid, a constituent of the systemic acquired resistance pathway, would elicit the emission of defense-related volatiles in citrus foliage, and what effect this might have on the host-plant searching behavior of D. citri. Comparisons were made of volatiles emitted from growing shoots of uninfected and Las-infected 'Valencia' sweet orange (Citrus sinensis) trees over two consecutive sampling days. A settling behavioral assay was used to compare psyllid attraction to MJ-treated vs. Tween-treated citrus sprigs. All three main effects, Las infection status, plant signaler application, and sampling day, influenced the proportions of individual volatile compounds emitted in different treatment groups. MJ- and SA-treated trees had higher emission rates than Tween-treated trees. Methyl salicylate (MeSA) and β-caryophyllene were present in higher proportions in the volatiles collected from Las-infected + trees. On the other hand, Las-infected + MJ-treated trees emitted lower proportions of MeSA than did Las-infected + Tween-treated trees. Because MeSA is a key D. citri attractant, this result suggests that MJ application could suppress MeSA emission from Las-infected trees, an approach that could be used to discourage psyllid colonization during

  2. Exogenous application of the plant signalers methyl jasmonate and salicylic acid induces changes in volatile emissions from citrus foliage and influences the aggregation behavior of Asian citrus psyllid (Diaphorina citri), vector of Huanglongbing

    Robbins, Paul S.; Niedz, Randy; McCollum, Greg; Alessandro, Rocco

    2018-01-01

    Huanglongbing, also known as citrus greening, is a destructive disease that threatens citrus production worldwide. It is putatively caused by the phloem-limited bacterium Candidatus Liberibacter asiaticus (Las). Currently, the disease is untreatable and efforts focus on intensive insecticide use to control the vector, Asian citrus psyllid (Diaphorina citri). Emerging psyllid resistance to multiple insecticides has generated investigations into the use of exogenously applied signaling compounds to enhance citrus resistance to D. citri and Las. In the present study, we examined whether foliar applications of methyl jasmonate (MJ), a volatile signaling compound associated with the induced systemic resistance pathway, and salicylic acid, a constituent of the systemic acquired resistance pathway, would elicit the emission of defense-related volatiles in citrus foliage, and what effect this might have on the host-plant searching behavior of D. citri. Comparisons were made of volatiles emitted from growing shoots of uninfected and Las-infected ‘Valencia’ sweet orange (Citrus sinensis) trees over two consecutive sampling days. A settling behavioral assay was used to compare psyllid attraction to MJ-treated vs. Tween-treated citrus sprigs. All three main effects, Las infection status, plant signaler application, and sampling day, influenced the proportions of individual volatile compounds emitted in different treatment groups. MJ- and SA-treated trees had higher emission rates than Tween-treated trees. Methyl salicylate (MeSA) and β-caryophyllene were present in higher proportions in the volatiles collected from Las-infected + trees. On the other hand, Las-infected + MJ-treated trees emitted lower proportions of MeSA than did Las-infected + Tween-treated trees. Because MeSA is a key D. citri attractant, this result suggests that MJ application could suppress MeSA emission from Las-infected trees, an approach that could be used to discourage psyllid colonization during

  3. Jasmonic Acid Enhances Al-Induced Root Growth Inhibition.

    Yang, Zhong-Bao; He, Chunmei; Ma, Yanqi; Herde, Marco; Ding, Zhaojun

    2017-02-01

    Phytohormones such as ethylene and auxin are involved in the regulation of the aluminum (Al)-induced root growth inhibition. Although jasmonate (JA) has been reported to play a crucial role in the regulation of root growth and development in response to environmental stresses through interplay with ethylene and auxin, its role in the regulation of root growth response to Al stress is not yet known. In an attempt to elucidate the role of JA, we found that exogenous application of JA enhanced the Al-induced root growth inhibition. Furthermore, phenotype analysis with mutants defective in either JA biosynthesis or signaling suggests that JA is involved in the regulation of Al-induced root growth inhibition. The expression of the JA receptor CORONATINE INSENSITIVE1 (COI1) and the key JA signaling regulator MYC2 was up-regulated in response to Al stress in the root tips. This process together with COI1-mediated Al-induced root growth inhibition under Al stress was controlled by ethylene but not auxin. Transcriptomic analysis revealed that many responsive genes under Al stress were regulated by JA signaling. The differential responsive of microtubule organization-related genes between the wild-type and coi1-2 mutant is consistent with the changed depolymerization of cortical microtubules in coi1 under Al stress. In addition, ALMT-mediated malate exudation and thus Al exclusion from roots in response to Al stress was also regulated by COI1-mediated JA signaling. Together, this study suggests that root growth inhibition is regulated by COI1-mediated JA signaling independent from auxin signaling and provides novel insights into the phytohormone-mediated root growth inhibition in response to Al stress. © 2017 American Society of Plant Biologists. All Rights Reserved.

  4. The Arabidopsis mutant cev1 links cell wall signaling to jasmonate and ethylene responses.

    Ellis, Christine; Karafyllidis, Ioannis; Wasternack, Claus; Turner, John G

    2002-07-01

    Biotic and abiotic stresses stimulate the synthesis of jasmonates and ethylene, which, in turn, induce the expression of genes involved in stress response and enhance defense responses. The cev1 mutant has constitutive expression of stress response genes and has enhanced resistance to fungal pathogens. Here, we show that cev1 plants have increased production of jasmonate and ethylene and that its phenotype is suppressed by mutations that interrupt jasmonate and ethylene signaling. Genetic mapping, complementation analysis, and sequence analysis revealed that CEV1 is the cellulose synthase CeSA3. CEV1 was expressed predominantly in root tissues, and cev1 roots contained less cellulose than wild-type roots. Significantly, the cev1 mutant phenotype could be reproduced by treating wild-type plants with cellulose biosynthesis inhibitors, and the cellulose synthase mutant rsw1 also had constitutive expression of VSP. We propose that the cell wall can signal stress responses in plants.

  5. Analyses of Catharanthus roseus and Arabidopsis thaliana WRKY transcription factors reveal involvement in jasmonate signaling.

    Schluttenhofer, Craig; Pattanaik, Sitakanta; Patra, Barunava; Yuan, Ling

    2014-06-20

    To combat infection to biotic stress plants elicit the biosynthesis of numerous natural products, many of which are valuable pharmaceutical compounds. Jasmonate is a central regulator of defense response to pathogens and accumulation of specialized metabolites. Catharanthus roseus produces a large number of terpenoid indole alkaloids (TIAs) and is an excellent model for understanding the regulation of this class of valuable compounds. Recent work illustrates a possible role for the Catharanthus WRKY transcription factors (TFs) in regulating TIA biosynthesis. In Arabidopsis and other plants, the WRKY TF family is also shown to play important role in controlling tolerance to biotic and abiotic stresses, as well as secondary metabolism. Here, we describe the WRKY TF families in response to jasmonate in Arabidopsis and Catharanthus. Publically available Arabidopsis microarrays revealed at least 30% (22 of 72) of WRKY TFs respond to jasmonate treatments. Microarray analysis identified at least six jasmonate responsive Arabidopsis WRKY genes (AtWRKY7, AtWRKY20, AtWRKY26, AtWRKY45, AtWRKY48, and AtWRKY72) that have not been previously reported. The Catharanthus WRKY TF family is comprised of at least 48 members. Phylogenetic clustering reveals 11 group I, 32 group II, and 5 group III WRKY TFs. Furthermore, we found that at least 25% (12 of 48) were jasmonate responsive, and 75% (9 of 12) of the jasmonate responsive CrWRKYs are orthologs of AtWRKYs known to be regulated by jasmonate. Overall, the CrWRKY family, ascertained from transcriptome sequences, contains approximately 75% of the number of WRKYs found in other sequenced asterid species (pepper, tomato, potato, and bladderwort). Microarray and transcriptomic data indicate that expression of WRKY TFs in Arabidopsis and Catharanthus are under tight spatio-temporal and developmental control, and potentially have a significant role in jasmonate signaling. Profiling of CrWRKY expression in response to jasmonate treatment

  6. Effect of methyl jasmonate application to grapevine leaves on grape amino acid content.

    Garde-Cerdán, Teresa; Portu, Javier; López, Rosa; Santamaría, Pilar

    2016-07-15

    Over the last few years, considerable attention has been paid to the application of elicitors to vineyard. However, research about the effect of elicitors on grape amino acid content is scarce. Therefore, the aim of this study was to evaluate the influence of foliar application of methyl jasmonate on must amino acid content. Results revealed that total amino acid content was not modified by the application of methyl jasmonate. However, the individual content of certain amino acids was increased as consequence of methyl jasmonate foliar application, i.e., histidine, serine, tryptophan, phenylalanine, tyrosine, asparagine, methionine, and lysine. Among them, phenylalanine content was considerably increased; this amino acid is precursor of phenolic and aromatic compounds. In conclusion, foliar application of methyl jasmonate improved must nitrogen composition. This finding suggests that methyl jasmonate treatment might be conducive to obtain wines of higher quality since must amino acid composition could affect the wine volatile composition and the fermentation kinetics. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. Fatty acid-amino acid conjugates are essential for systemic activation of salicylic acid-induced protein kinase and accumulation of jasmonic acid in Nicotiana attenuata.

    Hettenhausen, Christian; Heinrich, Maria; Baldwin, Ian T; Wu, Jianqiang

    2014-11-28

    Herbivory induces the activation of mitogen-activated protein kinases (MAPKs), the accumulation of jasmonates and defensive metabolites in damaged leaves and in distal undamaged leaves. Previous studies mainly focused on individual responses and a limited number of systemic leaves, and more research is needed for a better understanding of how different plant parts respond to herbivory. In the wild tobacco Nicotiana attenuata, FACs (fatty acid-amino acid conjugates) in Manduca sexta oral secretions (OS) are the major elicitors that induce herbivory-specific signaling but their role in systemic signaling is largely unknown. Here, we show that simulated herbivory (adding M. sexta OS to fresh wounds) dramatically increased SIPK (salicylic acid-induced protein kinase) activity and jasmonic acid (JA) levels in damaged leaves and in certain (but not all) undamaged systemic leaves, whereas wounding alone had no detectable systemic effects; importantly, FACs and wounding are both required for activating these systemic responses. In contrast to the activation of SIPK and elevation of JA in specific systemic leaves, increases in the activity of an important anti-herbivore defense, trypsin proteinase inhibitor (TPI), were observed in all systemic leaves after simulated herbivory, suggesting that systemic TPI induction does not require SIPK activation and JA increases. Leaf ablation experiments demonstrated that within 10 minutes after simulated herbivory, a signal (or signals) was produced and transported out of the treated leaves, and subsequently activated systemic responses. Our results reveal that N. attenuata specifically recognizes herbivore-derived FACs in damaged leaves and rapidly send out a long-distance signal to phylotactically connected leaves to activate MAPK and JA signaling, and we propose that FACs that penetrated into wounds rapidly induce the production of another long-distance signal(s) which travels to all systemic leaves and activates TPI defense.

  8. Improving Wheat Growth and Yield Using Chlormequat Chloride, Salicylic Acid and Jasmonic Acid under Water Stress

    N Vahabi

    2017-06-01

    measured by a water meter. Results and Discussion The results showed that water stress decreased flag leaf area, ear length, grain number per ear, biological yield and grain yield in the greenhouse and biological yield and grain yield in the field experiment. The maximum of flag leaf area was obtained at anthesis and after that there was no increase in green area. In the other hand, ear length and grain number per ear were fixed at anthesis and so drought stress had less negative impact on flag leaf area, ear length and grain number per ear under field conditions. Increasing the level of drought stress was considerably associated with greater reduction in grain yield and yield components. However, PGRS application improved yield components and consequently enhanced the grain yield. The higher flag leaf area in PGRs-treated plants might be due to lowering developmental rate or delaying plant maturity and senescence. So, by improving leaf area, PGR application resulted in increased photosynthetic rate leading to a higher yield. Although all PGRs had positive effect on growth and yield of wheat nevertheless, the effect of chlormequat chloride followed by salicylic acid was greater than jasmonic acid; so that foliar applications of chlormequat chloride, salicylic acid and jasmonic acid were associated with 20.7%, 13.8% and 7.24% increase in grain yield, respectively, under controlled conditions. These values were 18.3%, 12.2% and 8.1% for the field experiment. Such compensatory effects of PGRs could be due to various reasons. Chlormequat chloride can stimulate root growth, reduce transpiration, increase water use efficiency, and prevent chlorophyll destruction. Similarly, SA application may result in stomatal closure, increased WUE, increased chlorophyll content, increased respiratory-pathways and intercellular CO2 concentration, and stimulatory changes in other physiological and biochemical attributes. Jasmonic acid is also essential components for the signaling pathway

  9. Fatty acid and sterol contents during tulip leaf senescence induced by methyl jasmonate

    Marian Saniewski

    2013-12-01

    Full Text Available It has been shown previously that methyl jasmonate (JA-Me applied in lanolin paste on the bottom surface of intact tulip leaves causes a rapid and intense its senescence. The aim of this work was to study the effect of JA-Me on free and bound fatty acid and sterol contents during tulip leaf senescence. The main free and bound fatty acids of tulip leaf, in decreasing order of their abundance, were linolenic, linoleic, palmitic, oleic, stearic and myristic acids. Only the content of free linolenic acid decreased after treatment with JA-Me during visible stage of senescence. ß-Sitosterol (highest concentration, campesterol, stigmasterol and cholesterol were identified in tulip leaf. Methyl jasmonate evidently increased the level of ß-sitosterol, campesterol and stigmasterol during induced senescence. It is suggested that the increase in sterol concentrations under the influence of methyl jasmonate induced changes in membrane fluidity and permeability, which may be responsible for senescence.

  10. Salicylic acid and jasmonic acid are essential for systemic resistance against tobacco mosaic virus in Nicotiana benthamiana.

    Zhu, Feng; Xi, De-Hui; Yuan, Shu; Xu, Fei; Zhang, Da-Wei; Lin, Hong-Hui

    2014-06-01

    Systemic resistance is induced by pathogens and confers protection against a broad range of pathogens. Recent studies have indicated that salicylic acid (SA) derivative methyl salicylate (MeSA) serves as a long-distance phloem-mobile systemic resistance signal in tobacco, Arabidopsis, and potato. However, other experiments indicate that jasmonic acid (JA) is a critical mobile signal. Here, we present evidence suggesting both MeSA and methyl jasmonate (MeJA) are essential for systemic resistance against Tobacco mosaic virus (TMV), possibly acting as the initiating signals for systemic resistance. Foliar application of JA followed by SA triggered the strongest systemic resistance against TMV. Furthermore, we use a virus-induced gene-silencing-based genetics approach to investigate the function of JA and SA biosynthesis or signaling genes in systemic response against TMV infection. Silencing of SA or JA biosynthetic and signaling genes in Nicotiana benthamiana plants increased susceptibility to TMV. Genetic experiments also proved the irreplaceable roles of MeSA and MeJA in systemic resistance response. Systemic resistance was compromised when SA methyl transferase or JA carboxyl methyltransferase, which are required for MeSA and MeJA formation, respectively, were silenced. Moreover, high-performance liquid chromatography-mass spectrometry analysis indicated that JA and MeJA accumulated in phloem exudates of leaves at early stages and SA and MeSA accumulated at later stages, after TMV infection. Our data also indicated that JA and MeJA could regulate MeSA and SA production. Taken together, our results demonstrate that (Me)JA and (Me)SA are required for systemic resistance response against TMV.

  11. Bioassays for assesing jasmonate-dependent defenses triggered by pathogens, herbivorous insects, or beneficial rhizobacteria. In: Jasmonate Signaling - Methods and Protocols

    van Wees, S.C.M.; van Pelt, J.A.; Bakker, P.A.H.M.; Pieterse, C.M.J.

    2013-01-01

    Jasmonates, together with other plant hormones, are important orchestrators of the plant immune system. The different hormone-controlled signaling pathways cross-communicate in an antagonistic or a synergistic manner, providing the plant with a powerful capacity to fi nely regulate its immune

  12. Arabidopsis MYC Transcription Factors Are the Target of Hormonal Salicylic Acid/Jasmonic Acid Cross Talk in Response to Pieris brassicae Egg Extract.

    Schmiesing, André; Emonet, Aurélia; Gouhier-Darimont, Caroline; Reymond, Philippe

    2016-04-01

    Arabidopsis (Arabidopsis thaliana) plants recognize insect eggs and activate the salicylic acid (SA) pathway. As a consequence, expression of defense genes regulated by the jasmonic acid (JA) pathway is suppressed and larval performance is enhanced. Cross talk between defense signaling pathways is common in plant-pathogen interactions, but the molecular mechanism mediating this phenomenon is poorly understood. Here, we demonstrate that egg-induced SA/JA antagonism works independently of the APETALA2/ETHYLENE RESPONSE FACTOR (AP2/ERF) transcription factor ORA59, which controls the ERF branch of the JA pathway. In addition, treatment with egg extract did not enhance expression or stability of JASMONATE ZIM-domain transcriptional repressors, and SA/JA cross talk did not involve JASMONATE ASSOCIATED MYC2-LIKEs, which are negative regulators of the JA pathway. Investigating the stability of MYC2, MYC3, and MYC4, three basic helix-loop-helix transcription factors that additively control jasmonate-related defense responses, we found that egg extract treatment strongly diminished MYC protein levels in an SA-dependent manner. Furthermore, we identified WRKY75 as a novel and essential factor controlling SA/JA cross talk. These data indicate that insect eggs target the MYC branch of the JA pathway and uncover an unexpected modulation of SA/JA antagonism depending on the biological context in which the SA pathway is activated. © 2016 American Society of Plant Biologists. All Rights Reserved.

  13. Arabidopsis MYC Transcription Factors Are the Target of Hormonal Salicylic Acid/Jasmonic Acid Cross Talk in Response to Pieris brassicae Egg Extract1[OPEN

    Schmiesing, André; Gouhier-Darimont, Caroline

    2016-01-01

    Arabidopsis (Arabidopsis thaliana) plants recognize insect eggs and activate the salicylic acid (SA) pathway. As a consequence, expression of defense genes regulated by the jasmonic acid (JA) pathway is suppressed and larval performance is enhanced. Cross talk between defense signaling pathways is common in plant-pathogen interactions, but the molecular mechanism mediating this phenomenon is poorly understood. Here, we demonstrate that egg-induced SA/JA antagonism works independently of the APETALA2/ETHYLENE RESPONSE FACTOR (AP2/ERF) transcription factor ORA59, which controls the ERF branch of the JA pathway. In addition, treatment with egg extract did not enhance expression or stability of JASMONATE ZIM-domain transcriptional repressors, and SA/JA cross talk did not involve JASMONATE ASSOCIATED MYC2-LIKEs, which are negative regulators of the JA pathway. Investigating the stability of MYC2, MYC3, and MYC4, three basic helix-loop-helix transcription factors that additively control jasmonate-related defense responses, we found that egg extract treatment strongly diminished MYC protein levels in an SA-dependent manner. Furthermore, we identified WRKY75 as a novel and essential factor controlling SA/JA cross talk. These data indicate that insect eggs target the MYC branch of the JA pathway and uncover an unexpected modulation of SA/JA antagonism depending on the biological context in which the SA pathway is activated. PMID:26884488

  14. Allene oxide synthase, allene oxide cyclase and jasmonic acid levels in Lotus japonicus nodules.

    Anna Zdyb

    Full Text Available Jasmonic acid (JA, its derivatives and its precursor cis-12-oxo phytodienoic acid (OPDA form a group of phytohormones, the jasmonates, representing signal molecules involved in plant stress responses, in the defense against pathogens as well as in development. Elevated levels of JA have been shown to play a role in arbuscular mycorrhiza and in the induction of nitrogen-fixing root nodules. In this study, the gene families of two committed enzymes of the JA biosynthetic pathway, allene oxide synthase (AOS and allene oxide cyclase (AOC, were characterized in the determinate nodule-forming model legume Lotus japonicus JA levels were to be analysed in the course of nodulation. Since in all L. japonicus organs examined, JA levels increased upon mechanical disturbance and wounding, an aeroponic culture system was established to allow for a quick harvest, followed by the analysis of JA levels in whole root and shoot systems. Nodulated plants were compared with non-nodulated plants grown on nitrate or ammonium as N source, respectively, over a five week-period. JA levels turned out to be more or less stable independently of the growth conditions. However, L. japonicus nodules formed on aeroponically grown plants often showed patches of cells with reduced bacteroid density, presumably a stress symptom. Immunolocalization using a heterologous antibody showed that the vascular systems of these nodules also seemed to contain less AOC protein than those of nodules of plants grown in perlite/vermiculite. Hence, aeroponically grown L. japonicus plants are likely to be habituated to stress which could have affected JA levels.

  15. Memory responses of jasmonic acid-associated Arabidopsis genes to a repeated dehydration stress.

    Liu, Ning; Staswick, Paul E; Avramova, Zoya

    2016-11-01

    Dehydration stress activates numerous genes co-regulated by diverse signaling pathways. Upon repeated exposures, however, a subset of these genes does not respond maintaining instead transcription at their initial pre-stressed levels ('revised-response' genes). Most of these genes are involved in jasmonic acid (JA) biosynthesis, JA-signaling and JA-mediated stress responses. How these JA-associated genes are regulated to provide different responses to similar dehydration stresses is an enigma. Here, we investigate molecular mechanisms that contribute to this transcriptional behavior. The memory-mechanism is stress-specific: one exposure to dehydration stress or to abscisic acid (ABA) is required to prevent transcription in the second. Both ABA-mediated and JA-mediated pathways are critical for the activation of these genes, but the two signaling pathways interact differently during a single or multiple encounters with dehydration stress. Synthesis of JA during the first (S1) but not the second dehydration stress (S2) accounts for the altered transcriptional responses. We propose a model for these memory responses, wherein lack of MYC2 and of JA synthesis in S2 is responsible for the lack of expression of downstream genes. The similar length of the memory displayed by different memory-type genes suggests biological relevance for transcriptional memory as a gene-regulating mechanism during recurring bouts of drought. © 2016 John Wiley & Sons Ltd.

  16. Jasmonic and salicylic acid response in the fern Azolla filiculoides and its cyanobiont.

    de Vries, Sophie; de Vries, Jan; Teschke, Hendrik; von Dahlen, Janina K; Rose, Laura E; Gould, Sven B

    2018-01-03

    Plants sense and respond to microbes utilizing a multilayered signalling cascade. In seed plants, the phytohormones jasmonic and salicylic acid (JA and SA) are key denominators of how plants respond to certain microbes. Their interplay is especially well-known for tipping the scales in plants' strategies of dealing with phytopathogens. In non-angiosperm lineages, the interplay is less well understood, but current data indicate that it is intertwined to a lesser extent and the canonical JA/SA antagonism appears to be absent. Here, we used the water fern Azolla filiculoides to gain insights into the fern's JA/SA signalling and the molecular communication with its unique nitrogen fixing cyanobiont Nostoc azollae, which the fern inherits both during sexual and vegetative reproduction. By mining large-scale sequencing data, we demonstrate that Azolla has most of the genetic repertoire to produce and sense JA and SA. Using qRT-PCR on the identified biosynthesis and signalling marker genes, we show that Azolla is responsive to exogenously applied SA. Furthermore, exogenous SA application influenced the abundance and gene expression of Azolla's cyanobiont. Our data provide a framework for JA/SA signalling in ferns and suggest that SA might be involved in Azolla's communication with its vertically inherited cyanobiont. © 2018 John Wiley & Sons Ltd.

  17. Root jasmonic acid synthesis and perception regulate folivore-induced shoot metabolites and increase Nicotiana attenuata resistance.

    Fragoso, Variluska; Rothe, Eva; Baldwin, Ian T; Kim, Sang-Gyu

    2014-06-01

    While jasmonic acid (JA) signaling is widely accepted as mediating plant resistance to herbivores, and the importance of the roots in plant defenses is recently being recognized, the role of root JA in the defense of above-ground parts remains unstudied. To restrict JA impairment to the roots, we micrografted wildtype Nicotiana attenuata shoots to the roots of transgenic plants impaired in JA signaling and evaluated ecologically relevant traits in the glasshouse and in nature. Root JA synthesis and perception are involved in regulating nicotine production in roots. Strikingly, systemic root JA regulated local leaf JA and abscisic acid (ABA) concentrations, which were associated with differences in nicotine transport from roots to leaves via the transpiration stream. Root JA signaling also regulated the accumulation of other shoot metabolites; together these account for differences in resistance against a generalist, Spodoptera littoralis, and a specialist herbivore, Manduca sexta. In N. attenuata's native habitat, silencing root JA synthesis increased the shoot damage inflicted by Empoasca leafhoppers, which are able to select natural jasmonate mutants. Silencing JA perception in roots also increased damage by Tupiocoris notatus. We conclude that attack from above-ground herbivores recruits root JA signaling to launch the full complement of plant defense responses. © 2014 Max Planck Society. New Phytologist © 2014 New Phytologist Trust.

  18. A chloroplast lipoxygenase is required for wound-induced jasmonic acid accumulation in Arabidopsis.

    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.

  19. Silverleaf whitefly induces salicylic acid defenses and suppresses effectual jasmonic acid defenses.

    Zarate, Sonia I; Kempema, Louisa A; Walling, Linda L

    2007-02-01

    The basal defenses important in curtailing the development of the phloem-feeding silverleaf whitefly (Bemisia tabaci type B; SLWF) on Arabidopsis (Arabidopsis thaliana) were investigated. Sentinel defense gene RNAs were monitored in SLWF-infested and control plants. Salicylic acid (SA)-responsive gene transcripts accumulated locally (PR1, BGL2, PR5, SID2, EDS5, PAD4) and systemically (PR1, BGL2, PR5) during SLWF nymph feeding. In contrast, jasmonic acid (JA)- and ethylene-dependent RNAs (PDF1.2, VSP1, HEL, THI2.1, FAD3, ERS1, ERF1) were repressed or not modulated in SLWF-infested leaves. To test for a role of SA and JA pathways in basal defense, SLWF development on mutant and transgenic lines that constitutively activate or impair defense pathways was determined. By monitoring the percentage of SLWF nymphs in each instar, we show that mutants that activate SA defenses (cim10) or impair JA defenses (coi1) accelerated SLWF nymphal development. Reciprocally, mutants that activate JA defenses (cev1) or impair SA defenses (npr1, NahG) slowed SLWF nymphal development. Furthermore, when npr1 plants, which do not activate downstream SA defenses, were treated with methyl jasmonate, a dramatic delay in nymph development was observed. Collectively, these results showed that SLWF-repressed, JA-regulated defenses were associated with basal defense to the SLWF.

  20. Silverleaf Whitefly Induces Salicylic Acid Defenses and Suppresses Effectual Jasmonic Acid Defenses1[W][OA

    Zarate, Sonia I.; Kempema, Louisa A.; Walling, Linda L.

    2007-01-01

    The basal defenses important in curtailing the development of the phloem-feeding silverleaf whitefly (Bemisia tabaci type B; SLWF) on Arabidopsis (Arabidopsis thaliana) were investigated. Sentinel defense gene RNAs were monitored in SLWF-infested and control plants. Salicylic acid (SA)-responsive gene transcripts accumulated locally (PR1, BGL2, PR5, SID2, EDS5, PAD4) and systemically (PR1, BGL2, PR5) during SLWF nymph feeding. In contrast, jasmonic acid (JA)- and ethylene-dependent RNAs (PDF1.2, VSP1, HEL, THI2.1, FAD3, ERS1, ERF1) were repressed or not modulated in SLWF-infested leaves. To test for a role of SA and JA pathways in basal defense, SLWF development on mutant and transgenic lines that constitutively activate or impair defense pathways was determined. By monitoring the percentage of SLWF nymphs in each instar, we show that mutants that activate SA defenses (cim10) or impair JA defenses (coi1) accelerated SLWF nymphal development. Reciprocally, mutants that activate JA defenses (cev1) or impair SA defenses (npr1, NahG) slowed SLWF nymphal development. Furthermore, when npr1 plants, which do not activate downstream SA defenses, were treated with methyl jasmonate, a dramatic delay in nymph development was observed. Collectively, these results showed that SLWF-repressed, JA-regulated defenses were associated with basal defense to the SLWF. PMID:17189328

  1. Arabidopsis MAP kinase 4 regulates salicylic acid- and jasmonic acid/ethylene-dependent responses via EDS1 and PAD4

    Brodersen, P; Petersen, M; 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...

  2. Fusion genetic analysis of jasmonate-signalling mutants in Arabidopsis

    Jensen, Anders Bøgh; Raventos, D.; Mundy, John Williams

    2002-01-01

    as two recessive mutants, designated joe1 and 2, that overexpress the reporter. Genetic analysis indicated that reporter overexpression in the joe mutants requires COI. joe1 responded to MeJA with increased anthocyanin accumulation, while joe2 responded with decreased root growth inhibition. In addition...... activity was also induced by the protein kinase inhibitor staurosporine and antagonized by the protein phosphatase inhibitor okadaic acid. FLUC bio-imaging, RNA gel-blot analysis and progeny analyses identified three recessive mutants that underexpress the FLUC reporter, designated jue1, 2 and 3, as well...

  3. Low concentrations of salicylic acid delay methyl jasmonate-induced leaf senescence by up-regulating nitric oxide synthase activity.

    Ji, Yingbin; Liu, Jian; Xing, Da

    2016-09-01

    In plants, extensive efforts have been devoted to understanding the crosstalk between salicylic acid (SA) and jasmonic acid (JA) signaling in pathogen defenses, but this crosstalk has scarcely been addressed during senescence. In this study, the effect of SA application on methyl jasmonate (MeJA)-induced leaf senescence was assessed. We found that low concentrations of SA (1-50 μM) played a delayed role against the senescence promoted by MeJA. Furthermore, low concentrations of SA enhanced plant antioxidant defenses and restricted reactive oxygen species (ROS) accumulation in MeJA-treated leaves. When applied simultaneously with MeJA, low concentrations of SA triggered a nitric oxide (NO) burst, and the elevated NO levels were linked to the nitric oxide associated 1 (NOA1)-dependent pathway via nitric oxide synthase (NOS) activity. The ability of SA to up-regulate plant antioxidant defenses, reduce ROS accumulation, and suppress leaf senescence was lost in NO-deficient Atnoa1 plants. In a converse manner, exogenous addition of NO donors increased the plant antioxidant capacity and lowered the ROS levels in MeJA-treated leaves. Taken together, the results indicate that SA at low concentrations counteracts MeJA-induced leaf senescence through NOA1-dependent NO signaling and strengthening of the antioxidant defense. © The Author 2016. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  4. Over-expression of VvWRKY1 in grapevines induces expression of jasmonic acid pathway-related genes and confers higher tolerance to the downy mildew.

    Chloé Marchive

    Full Text Available Most WRKY transcription factors activate expression of defence genes in a salicylic acid- and/or jasmonic acid-dependent signalling pathway. We previously identified a WRKY gene, VvWRKY1, which is able to enhance tolerance to fungal pathogens when it is overexpressed in tobacco. The present work analyzes the effects of VvWRKY1 overexpression in grapevine. Microarray analysis showed that genes encoding defence-related proteins were up-regulated in the leaves of transgenic 35S::VvWRKY1 grapevines. Quantitative RT-PCR analysis confirmed that three genes putatively involved in jasmonic acid signalling pathway were overexpressed in the transgenic grapes. The ability of VvWRKY1 to trans-activate the promoters of these genes was demonstrated by transient expression in grape protoplasts. The resistance to the causal agent of downy mildew, Plasmopara viticola, was enhanced in the transgenic plants. These results show that VvWRKY1 can increase resistance of grapevine against the downy mildew through transcriptional reprogramming leading to activation of the jasmonic acid signalling pathway.

  5. Development of an ultrahigh-performance liquid chromatography-electrospray ionization-tandem mass spectrometry method for the simultaneous determination of salicylic acid, jasmonic acid, and abscisic acid in rose leaves.

    Bosco, Renato; Daeseleire, Els; Van Pamel, Els; Scariot, Valentina; Leus, Leen

    2014-07-09

    This paper describes a method to detect and quantitate the endogenous plant hormones (±)-2-cis-4-trans-abscisic acid, (-)-jasmonic acid, and salicylic acid by means of ultrahigh-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) in hybrid rose leaf matrices. Deuterium-labeled [(2)H6] (+)-2-cis-4-trans-abscisic acid, [(2)H6] (±)-jasmonic acid, and [(2)H4]-salicylic acid were used as internal standards. Rose samples (10 mg) were extracted with methanol/water/acetic acid (10:89:1) and subsequently purified on an Oasis MCX 1 cm(3) Vac SPE cartridge. Performance characteristics were validated according to Commission Decision 2002/657/EC. Recovery, repeatability, and within-laboratory reproducibility were acceptable for all phytohormones tested at three different concentrations. The decision limit and detection capability for (±)-2-cis-4-trans-abscisic acid, (-)-jasmonic acid, and salicylic acid were 0.0075 and 0.015 μg/g, 0.00015 and 0.00030 μg/g, and 0.0089 and 0.018 μg/g, respectively. Matrix effects (signal suppression or enhancement) appeared to be high for all substances considered, implying the need for quantitation based on matrix-matched calibration curves.

  6. Costs of jasmonic acid induced defense in aboveground and belowground parts of corn (Zea mays L.).

    Feng, Yuanjiao; Wang, Jianwu; Luo, Shiming; Fan, Huizhi; Jin, Qiong

    2012-08-01

    Costs of jasmonic acid (JA) induced plant defense have gained increasing attention. In this study, JA was applied continuously to the aboveground (AG) or belowground (BG) parts, or AG plus BG parts of corn (Zea mays L.) to investigate whether JA exposure in one part of the plant would affect defense responses in another part, and whether or not JA induced defense would incur allocation costs. The results indicated that continuous JA application to AG parts systemically affected the quantities of defense chemicals in the roots, and vice versa. Quantities of DIMBOA and total amounts of phenolic compounds in leaves or roots generally increased 2 or 4 wk after the JA treatment to different plant parts. In the first 2 wk after application, the increase of defense chemicals in leaves and roots was accompanied by a significant decrease of root length, root surface area, and root biomass. Four weeks after the JA application, however, no such costs for the increase of defense chemicals in leaves and roots were detected. Instead, shoot biomass and root biomass increased. The results suggest that JA as a defense signal can be transferred from AG parts to BG parts of corn, and vice versa. Costs for induced defense elicited by continuous JA application were found in the early 2 wk, while distinct benefits were observed later, i.e., 4 wk after JA treatment.

  7. Plastic Transcriptomes Stabilize Immunity to Pathogen Diversity: The Jasmonic Acid and Salicylic Acid Networks within the Arabidopsis/Botrytis Pathosystem.

    Zhang, Wei; Corwin, Jason A; Copeland, Daniel; Feusier, Julie; Eshbaugh, Robert; Chen, Fang; Atwell, Susana; Kliebenstein, Daniel J

    2017-11-01

    To respond to pathogen attack, selection and associated evolution has led to the creation of plant immune system that are a highly effective and inducible defense system. Central to this system are the plant defense hormones jasmonic acid (JA) and salicylic acid (SA) and crosstalk between the two, which may play an important role in defense responses to specific pathogens or even genotypes. Here, we used the Arabidopsis thaliana - Botrytis cinerea pathosystem to test how the host's defense system functions against genetic variation in a pathogen. We measured defense-related phenotypes and transcriptomic responses in Arabidopsis wild-type Col-0 and JA- and SA-signaling mutants, coi1-1 and npr1-1 , individually challenged with 96 diverse B. cinerea isolates. Those data showed genetic variation in the pathogen influences on all components within the plant defense system at the transcriptional level. We identified four gene coexpression networks and two vectors of defense variation triggered by genetic variation in B. cinerea This showed that the JA and SA signaling pathways functioned to constrain/canalize the range of virulence in the pathogen population, but the underlying transcriptomic response was highly plastic. These data showed that plants utilize major defense hormone pathways to buffer disease resistance, but not the metabolic or transcriptional responses to genetic variation within a pathogen. © 2017 American Society of Plant Biologists. All rights reserved.

  8. Determination of proteins induced in response to jasmonic acid and salicylic acid in resistant and susceptible cultivars of tomato.

    Afroz, Amber; Khan, Muhammad Rashid; Komatsu, Setsuko

    2010-07-01

    Jasmonic acid (JA) and salicylic acid (SA) are signaling molecules that play key roles in the regulation of metabolic processes, reproduction, and defense against pathogens. The proteomics approach was used to identify proteins that are induced by JA and SA in the tomato cultivars Roma and Pant Bahr, which are susceptible and resistant to bacterial wilt, respectively. Threonine deaminase and leucine amino peptidase were upregulated, and ribulose-1,5-bisphosphate carboxylase/oxygenase small chain was downregulated by time-course application of JA. Translationally controlled tumor protein was upregulated by time-course application of SA. Protein disulfide isomerase was upregulated by application of either JA or SA. Proteins related to defense, energy, and protein destination/storage are suspected to be responsible for the susceptibility or resistance of the cultivars. Furthermore, in Roma, iron ABC transporter was upregulated by JA and down-regulated by SA. Iron ABC transporter plays a part in the signal transduction of both JA and SA in cultivars of tomato that are resistant to bacterial wilt.

  9. E-2-hexenal promotes susceptibility to Pseudomonas syringae by activating jasmonic acid pathways in Arabidopsis

    Alessandra eScala

    2013-04-01

    Full Text Available Green Leaf Volatiles (GLVs are C6-molecules - alcohols, aldehydes and esters - produced by plants upon herbivory or during pathogen infection. Exposure to this blend of volatiles induces defence-related responses in neighboring undamaged plants, thus assigning a role to GLVs in regulating plant defences. Here we compared Arabidopsis thaliana ecotype Ler with a hydroperoxide lyase line, hpl1, unable to synthesize GLVs, for susceptibility to Pseudomonas syringae pv. tomato (DC3000. We found that the growth of DC3000 was significantly reduced in the hpl1 mutant. This phenomenon correlated with lower jasmonic acid (JA levels and higher salicylic acid (SA levels in the hpl1 mutant. Furthermore, upon infection, the JA-responsive genes VSP2 and LEC were only slightly or not induced, respectively, in hpl1. This suggests that the reduced growth of DC3000 in hpl1 plants is due to the constraint of JA-dependent responses. Treatment of hpl1 plants with E-2-hexenal, one of the more reactive GLVs, prior to infection with DC3000, resulted in increased growth of DC3000 in hpl1, thus complementing this mutant. Interestingly, the growth of DC3000 also increased in Ler plants treated with E-2-hexenal. This stronger growth was not dependent on the JA-signaling component MYC2, but on ORA59, an integrator of JA and ethylene signaling pathways, and on the production of coronatine by DC3000. GLVs may have multiple effects on plant-pathogen interactions, in this case reducing resistance to P. syringae via JA and ORA59.

  10. The role of electrical and jasmonate signalling in the recognition of captured prey in the carnivorous sundew plant Drosera capensis

    Krausko, M.; Perůtka, M.; Šebela, M.; Šamajová, O.; Šamaj, J.; Novák, Ondřej; Pavlovič, A.

    2017-01-01

    Roč. 213, č. 4 (2017), s. 1818-1835 ISSN 0028-646X R&D Projects: GA MŠk(CZ) LO1204 Institutional support: RVO:61389030 Keywords : action potential * carnivorous plant * Drosera * electrical signal * enzymes * jasmonates * long-distance signalling * sundew Subject RIV: EB - Genetics ; Molecular Biology OBOR OECD: Plant sciences, botany Impact factor: 7.330, year: 2016

  11. Jasmonic acid distribution and action in plants: regulation during development and response to biotic and abiotic stress.

    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.

  12. Lasiojasmonates A-C, three jasmonic acid esters produced by Lasiodiplodia sp., a grapevine pathogen.

    Andolfi, Anna; Maddau, Lucia; Cimmino, Alessio; Linaldeddu, Benedetto T; Basso, Sara; Deidda, Antonio; Serra, Salvatorica; Evidente, Antonio

    2014-07-01

    In this study, a strain (BL 101) of a species of Lasiodiplodia, not yet formally described, which was isolated from declining grapevine plants showing wedge-shaped cankers, was investigated for its ability to produce in vitro bioactive secondary metabolites. From culture filtrates of this strain three jasmonic acid esters, named lasiojasmonates A-C and 16-O-acetylbotryosphaerilactones A and C were isolated together with (1R,2R)-jasmonic acid, its methyl ester, botryosphaerilactone A, (3S,4R,5R)-4-hydroxymethyl-3,5-dimethyldihydro-2-furanone and (3R,4S)-botryodiplodin. The structures of lasiojasmonates A-C were established by spectroscopic methods as (1R*,2R*,3'S*,4'R*,5'R*)-4-hydroxymethyl-3,5-dimethyldihydro-2-furanone, (1R*,2R*,3'S*,4'R*,5'R*,10'R*,12'R*,13'R*,14'S*) and (1R*,2R*,3'S*,4'R*,5'R*,10'S*,12'R*,13'R*,14'S*)-4-(4-hydroxymethyl-3,5-dimethyltetrahydro-furan-2-yloxymethyl)-3,5-dimethyldihydro-2-furanones jasmonates (1, 4 and 5). The structures of 16-O-acetylbotryosphaerilactones A and C were determined by comparison of their spectral data with those of the corresponding acetyl derivatives obtained by acetylation of botryosphaerilactone A. The metabolites isolated, except 4 and 5, were tested at 1mg/mL on leaves of grapevine cv. Cannonau and cork oak using the leaf puncture assay. They were also tested on detached grapevine leaves at 0.5mg/mL and tomato cuttings at 0.1mg/mL. In all phytotoxic assays only jasmonic acid was found to be active. All metabolites were inactive in the zootoxic assay at 50 μg/mL. Copyright © 2014. Published by Elsevier Ltd.

  13. ERECTA, salicylic acid, abscisic acid, and jasmonic acid modulate quantitative disease resistance of Arabidopsis thaliana to Verticillium longisporum.

    Häffner, Eva; Karlovsky, Petr; Splivallo, Richard; Traczewska, Anna; Diederichsen, Elke

    2014-04-01

    Verticillium longisporum is a soil-borne vascular pathogen infecting cruciferous hosts such as oilseed rape. Quantitative disease resistance (QDR) is the major control means, but its molecular basis is poorly understood so far. Quantitative trait locus (QTL) mapping was performed using a new (Bur×Ler) recombinant inbred line (RIL) population of Arabidopsis thaliana. Phytohormone measurements and analyses in defined mutants and near-isogenic lines (NILs) were used to identify genes and signalling pathways that underlie different resistance QTL. QTL for resistance to V. longisporum-induced stunting, systemic colonization by the fungus and for V. longisporum-induced chlorosis were identified. Stunting resistance QTL were contributed by both parents. The strongest stunting resistance QTL was shown to be identical with Erecta. A functional Erecta pathway, which was present in Bur, conferred partial resistance to V. longisporum-induced stunting. Bur showed severe stunting susceptibility in winter. Three stunting resistance QTL of Ler origin, two co-localising with wall-associated kinase-like (Wakl)-genes, were detected in winter. Furthermore, Bur showed a much stronger induction of salicylic acid (SA) by V. longisporum than Ler. Systemic colonization was controlled independently of stunting. The vec1 QTL on chromosome 2 had the strongest effect on systemic colonization. The same chromosomal region controlled the level of abscisic acid (ABA) and jasmonic acid (JA) in response to V. longisporum: The level of ABA was higher in colonization-susceptible Ler than in colonization-resistant Bur after V. longisporum infection. JA was down-regulated in Bur after infection, but not in Ler. These differences were also demonstrated in NILs, varying only in the region containing vec1. All phytohormone responses were shown to be independent of Erecta. Signalling systems with a hitherto unknown role in the QDR of A. thaliana against V. longisporum were identified: Erecta mediated

  14. Fatty acid and sterol contents during methyl jasmonate-induced leaf abscission in Kalanchoe blossfeldiana

    Marian Saniewski

    2013-12-01

    Full Text Available It was found previously that methyl jasmonate (JA-Me induced leaf abscission in Kalanchoe blossfeldiana. In present studies it was showed that JA-Me did not affect or only slightly affected the content of free and bound fatty acids in petioles and blades. ß-Sitosterol, campesterol and ß-amyrin were identified in petioles and blades of K. blossfeldiana; JA-Me decreased the content of campesterol in petioles and increased the content of ß-sitosterol in blades. In blades of plants treated with JA-Me disappearance of olean-12-one was indicated but appearance of 2H-cyclopropa[a]-naphthalen-2-one,l, la, 4, 5, 6, 7, 7a, 7b-octahydro-l, 1, 7, 7a-tetramethyl (aristolone was documented. The significance of these findings in leaf abscission induced by methyl jasmonate in K. blossfeldiana is discussed.

  15. WRKY Transcription Factors: Key Components in Abscisic Acid Signaling

    2011-01-01

    networks that take inputs from numerous stimuli and that they are involved in mediating responses to numerous phytohormones including salicylic acid ... jasmonic acid , ABA and GA. These roles in multiple signalling pathways may in turn partly explain the pleiotropic effects commonly seen when TF genes are...Review article WRKY transcription factors: key components in abscisic acid signalling Deena L. Rushton1, Prateek Tripathi1, Roel C. Rabara1, Jun Lin1

  16. Surfactin Protects Wheat against Zymoseptoria tritici and Activates Both Salicylic Acid- and Jasmonic Acid-Dependent Defense Responses

    Geraldine Le Mire

    2018-01-01

    Full Text Available Natural elicitors induce plant resistance against a broad spectrum of diseases, and are currently among the most promising biocontrol tools. The present study focuses on the elicitor properties of the cyclic lipopeptide surfactin on wheat, in order to stimulate the defenses of this major crop against the challenging fungal pathogen Zymoseptoria tritici. The protection efficacy of surfactin extracted from the strain Bacillus amyloliquefaciens S499 was investigated through greenhouse trials. Surfactin protected wheat by 70% against Z. tritici, similarly to the chemical reference elicitor Bion®50WG. In vitro biocidal assays revealed no antifungal activities of surfactin towards the pathogen. A biomolecular RT-qPCR based low-density microarray tool was used to study the relative expression of 23 wheat defense genes. Surfactin significantly induced wheat natural defenses by stimulating both salicylic acid- and jasmonic acid-dependent signaling pathways. Surfactin was successfully tested as an elicitor on the pathosystem wheat–Z. tritici. These results promote further sustainable agricultural practices and the reduction of chemical inputs.

  17. Alpha-momorcharin enhances Tobacco mosaic virus resistance in tobaccoNN by manipulating jasmonic acid-salicylic acid crosstalk.

    Yang, Ting; Zhu, Li-Sha; Meng, Yao; Lv, Rui; Zhou, Zhuo; Zhu, Lin; Lin, Hong-Hui; Xi, De-Hui

    2018-04-01

    Alpha-momorcharin (α-MMC) is a type-I ribosome inactivating protein (RIP) with a molecular weight of 29 kDa found in plants. This protein has been shown to be effective against a broad range of human viruses and also has anti-tumor activities. However, the mechanism by which α-MMC induces plant defense responses and regulates the N gene to promote resistance to the Tobacco mosaic virus (TMV) is still not clear. By using pharmacological and infection experiments, we found that α-MMC enhances TMV resistance of tobacco plants containing the N gene (tobacco NN ). Our results showed that plants pretreated with 0.5 mg/ml α-MMC could relieve TMV-induced oxidative damage, had enhanced the expression of the N gene and increased biosynthesis of jasmonic acid (JA) and salicylic acid (SA). Moreover, transcription of JA and SA signaling pathway genes were increased, and their expression persisted for a longer period of time in plants pretreated with α-MMC compared with those pretreated with water. Importantly, exogenous application of 1-Aminobenzotriazole (ABT, SA inhibitor) and ibuprofen (JA inhibitor) reduced α-MMC induced plant resistance under viral infection. Thus, our results revealed that α-MMC enhances TMV resistance of tobacco NN plants by manipulating JA-SA crosstalk. Copyright © 2017 Elsevier GmbH. All rights reserved.

  18. Effect of postharvest methyl jasmonate treatment on fatty acid composition and phenolic acid content in olive fruits during storage.

    Flores, Gema; Blanch, Gracia Patricia; Del Castillo, María Luisa Ruiz

    2017-07-01

    The nutritional effects of both table olives and olive oil are attributed not only to their fatty acids but also to antioxidant phenolics such as phenolic acids. Delays in oil processing usually result in undesirable oxidation and hydrolysis processes leading to formation of free fatty acids. These alterations create the need to process oil immediately after olive harvest. However, phenolic content decreases drastically during olive storage resulting in lower quality oil. In the present study we propose postharvest methyl jasmonate treatment as a mean to avoid changes in fatty acid composition and losses of phenolic acids during olive storage. Contents of fatty acids and phenolic acids were estimated in methyl jasmonate treated olives throughout 30-day storage, as compared with those of untreated olives. Significant decreases of saturated fatty acids were observed in treated samples whereas increases of oleic, linoleic and linolenic acids were respectively measured (i.e. from 50.8% to 64.5%, from 7.2% to 9.1% and from 1.5% to 9.3%). Also, phenolic acid contents increased significantly in treated olives. Particularly, increases of gallic acid from 1.35 to 6.29 mg kg -1 , chlorogenic acid from 9.18 to 16.21 mg kg -1 , vanillic acid from 9.61 to 16.99 mg kg -1 , caffeic acid from 5.12 to 12.55 mg kg -1 , p-coumaric acid from 0.96 to 5.31 mg kg -1 and ferulic acid from 4.05 to 10.43 mg kg -1 were obtained. Methyl jasmonate treatment is proposed as an alternative postharvest technique to traditional methods to guarantee olive oil quality when oil processing is delayed and olive fruits have to necessarily to be stored. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  19. Ozone Sensitivity in Hybrid Poplar Correlates with Insensitivity to Both Salicylic Acid and Jasmonic Acid. The Role of Programmed Cell Death in Lesion Formation1

    Koch, Jennifer Riehl; Creelman, Robert A.; Eshita, Steven M.; Seskar, Mirjana; Mullet, John E.; Davis, Keith R.

    2000-01-01

    Our earlier studies demonstrated that the ozone-sensitive hybrid poplar clone NE-388 displays an attenuated level of ozone-, wound-, and phytopathogen-induced defense gene expression. To determine if this reduced gene activation involves signal transduction pathways dependent on salicylic acid (SA) and/or jasmonic acid (JA), we compared the responses of NE-388 and an ozone-tolerant clone, NE-245, to these signal molecules. JA levels increased in both clones in response to ozone, but only minimal increases in SA levels were measured for either clone. Treatment with SA and methyl jasmonate induced defense gene expression only in NE-245, indicating that NE-388 is insensitive to these signal molecules. DNA fragmentation, an indicator of programmed cell death (PCD), was detected in NE-245 treated with either ozone or an avirulent phytopathogen, but was not detected in NE-388. We conclude that these clones undergo two distinct mechanisms of ozone-induced lesion formation. In NE-388, lesions appear to be due to toxic cell death resulting from a limited ability to perceive and subsequently activate SA- and/or JA-mediated antioxidant defense responses. In NE-245, SA-dependent PCD precedes lesion formation via a process related to the PCD pathway activated by phytopathogenic bacteria. These results support the hypothesis that ozone triggers a hypersensitive response. PMID:10859179

  20. Ozone sensitivity in hybrid poplar correlates with insensitivity to both salicylic acid and jasmonic acid. The role of programmed cell death in lesion formation.

    Koch, J R; Creelman, R A; Eshita, S M; Seskar, M; Mullet, J E; Davis, K R

    2000-06-01

    Our earlier studies demonstrated that the ozone-sensitive hybrid poplar clone NE-388 displays an attenuated level of ozone-, wound-, and phytopathogen-induced defense gene expression. To determine if this reduced gene activation involves signal transduction pathways dependent on salicylic acid (SA) and/or jasmonic acid (JA), we compared the responses of NE-388 and an ozone-tolerant clone, NE-245, to these signal molecules. JA levels increased in both clones in response to ozone, but only minimal increases in SA levels were measured for either clone. Treatment with SA and methyl jasmonate induced defense gene expression only in NE-245, indicating that NE-388 is insensitive to these signal molecules. DNA fragmentation, an indicator of programmed cell death (PCD), was detected in NE-245 treated with either ozone or an avirulent phytopathogen, but was not detected in NE-388. We conclude that these clones undergo two distinct mechanisms of ozone-induced lesion formation. In NE-388, lesions appear to be due to toxic cell death resulting from a limited ability to perceive and subsequently activate SA- and/or JA-mediated antioxidant defense responses. In NE-245, SA-dependent PCD precedes lesion formation via a process related to the PCD pathway activated by phytopathogenic bacteria. These results support the hypothesis that ozone triggers a hypersensitive response.

  1. Influence of (9Z)-12-hydroxy-9-dodecenoic acid and methyl jasmonate on plant protein phosphorylation.

    Tarchevsky, I A; Karimova, F G; Grechkin, A N; Moukhametchina, N U

    2000-12-01

    The products of the lipoxygenase pathway, methyl jasmonic acid (MeJA) and (9Z)-12-hydroxy-9-dodecenoic acid (HDA), hardly changed the relative level of phosphorylated polypeptides (RLPPs) during 2 h of incubation: 15 and 17 kDa RLPPs were enhanced by HDA, but decreased by MeJA. RLPPs of 73 and 82 kDa were increased by both compounds. MeJA and HDA treatment induced specific and unspecific effects in some RLPPs. It was shown that HDA and MeJA increased protein kinase activity in the presence of 1 microM cAMP.

  2. Ecological trade-offs between jasmonic acid-dependent direct and indirect plant defences in tritrophic interactions.

    Wei, Jianing; Wang, Lizhong; Zhao, Jiuhai; Li, Chuanyou; Ge, Feng; Kang, Le

    2011-01-01

    Recent studies on plants genetically modified in jasmonic acid (JA) signalling support the hypothesis that the jasmonate family of oxylipins plays an important role in mediating direct and indirect plant defences. However, the interaction of two modes of defence in tritrophic systems is largely unknown. In this study, we examined the preference and performance of a herbivorous leafminer (Liriomyza huidobrensis) and its parasitic wasp (Opius dissitus) on three tomato genotypes: a wild-type (WT) plant, a JA biosynthesis (spr2) mutant, and a JA-overexpression 35S::prosys plant. Their proteinase inhibitor production and volatile emission were used as direct and indirect defence factors to evaluate the responses of leafminers and parasitoids. Here, we show that although spr2 mutant plants are compromised in direct defence against the larval leafminers and in attracting parasitoids, they are less attractive to adult flies compared with WT plants. Moreover, in comparison to other genotypes, the 35S::prosys plant displays greater direct and constitutive indirect defences, but reduced success of parasitism by parasitoids. Taken together, these results suggest that there are distinguished ecological trade-offs between JA-dependent direct and indirect defences in genetically modified plants whose fitness should be assessed in tritrophic systems and under natural conditions. © The Authors (2010). Journal compilation © New Phytologist Trust (2010).

  3. Jasmonic acid-isoleucine formation in grapevine (Vitis vinifera L.) by two enzymes with distinct transcription profiles.

    Böttcher, Christine; Burbidge, Crista A; di Rienzo, Valentina; Boss, Paul K; Davies, Christopher

    2015-07-01

    The plant hormone jasmonic acid (JA) is essential for stress responses and the formation of reproductive organs, but its role in fruit development and ripening is unclear. Conjugation of JA to isoleucine is a crucial step in the JA signaling pathway since only JA-Ile is recognized by the jasmonate receptor. The conjugation reaction is catalyzed by JA-amido synthetases, belonging to the family of Gretchen Hagen3 (GH3) proteins. Here, in vitro studies of two grapevine (Vitis vinifera L. cv Shiraz) GH3 enzymes, VvGH3-7 and VvGH3-9, demonstrated JA-conjugating activities with an overlapping range of amino acid substrates, including isoleucine. Expression studies of the corresponding genes in grape berries combined with JA and JA-Ile measurements suggested a primary role for JA signaling in fruit set and cell division and did not support an involvement of JA in the ripening process. In response to methyl JA (MeJA) treatment, and in wounded and unwounded (distal) leaves, VvGH3-9 transcripts accumulated, indicating a participation in the JA response. In contrast, VvGH3-7 was unresponsive to MeJA and local wounding, demonstrating a differential transcriptional regulation of VvGH3-7 and VvGH3-9. The transient induction of VvGH3-7 in unwounded, distal leaves was suggestive of the involvement of an unknown mobile wound signal. © 2014 Institute of Botany, Chinese Academy of Sciences.

  4. Transcriptome Analysis in Haematococcus pluvialis: Astaxanthin Induction by Salicylic Acid (SA) and Jasmonic Acid (JA).

    Gao, Zhengquan; Li, Yan; Wu, Guanxun; Li, Guoqiang; Sun, Haifeng; Deng, Suzhen; Shen, Yicheng; Chen, Guoqiang; Zhang, Ruihao; Meng, Chunxiao; Zhang, Xiaowen

    2015-01-01

    Haematococcus pluvialis is an astaxanthin-rich microalga that can increase its astaxanthin production by salicylic acid (SA) or jasmonic acid (JA) induction. The genetic transcriptome details of astaxanthin biosynthesis were analyzed by exposing the algal cells to 25 mg/L of SA and JA for 1, 6 and 24 hours, plus to the control (no stress). Based on the RNA-seq analysis, 56,077 unigenes (51.7%) were identified with functions in response to the hormone stress. The top five identified subcategories were cell, cellular process, intracellular, catalytic activity and cytoplasm, which possessed 5600 (~9.99%), 5302 (~9.45%), 5242 (~9.35%), 4407 (~7.86%) and 4195 (~7.48%) unigenes, respectively. Furthermore, 59 unigenes were identified and assigned to 26 putative transcription factors (TFs), including 12 plant-specific TFs. They were likely associated with astaxanthin biosynthesis in Haematococcus upon SA and JA stress. In comparison, the up-regulation of differential expressed genes occurred much earlier, with higher transcript levels in the JA treatment (about 6 h later) than in the SA treatment (beyond 24 h). These results provide valuable information for directing metabolic engineering efforts to improve astaxanthin biosynthesis in H. pluvialis.

  5. UV-C-Induced alleviation of transcriptional gene silencing through plant-plant communication: Key roles of jasmonic acid and salicylic acid pathways.

    Xu, Wei; Wang, Ting; Xu, Shaoxin; Li, Fanghua; Deng, Chenguang; Wu, Lijun; Wu, Yuejin; Bian, Po

    2016-08-01

    Plant stress responses at the epigenetic level are expected to allow more permanent changes of gene expression and potentially long-term adaptation. While it has been reported that plants subjected to adverse environments initiate various stress responses in their neighboring plants, little is known regarding epigenetic responses to external stresses mediated by plant-plant communication. In this study, we show that DNA repetitive elements of Arabidopsis thaliana, whose expression is inhibited epigenetically by transcriptional gene silencing (TGS) mechanism, are activated by UV-C irradiation through airborne plant-plant and plant-plant-plant communications, accompanied by DNA demethylation at CHH sites. Moreover, the TGS is alleviated by direct treatments with exogenous methyl jasmonate (MeJA) and methyl salicylate (MeSA). Further, the plant-plant and plant-plant-plant communications are blocked by mutations in the biosynthesis or signaling of jasmonic acid (JA) or salicylic acid (SA), indicating that JA and SA pathways are involved in the interplant communication for epigenetic responses. For the plant-plant-plant communication, stress cues are relayed to the last set of receiver plants by promoting the production of JA and SA signals in relaying plants, which exhibit upregulated expression of genes for JA and SA biosynthesis and enhanced emanation of MeJA and MeSA. Copyright © 2016 Elsevier B.V. All rights reserved.

  6. Nuclear jasmonate and salicylate signaling and crosstalk in defense against pathogens

    Roberto eSolano

    2013-04-01

    Full Text Available An extraordinary progress has been made over the last two decades on understanding the components and mechanisms governing plant innate immunity. After detection of a pathogen, effective plant resistance depends on the activation of a complex signaling network integrated by small signaling molecules and hormonal pathways, and the balance of these hormone systems determines resistance to particular pathogens. The discovery of new components of hormonal signaling pathways, including plant nuclear hormone receptors, is providing a picture of complex crosstalk and induced hormonal changes that modulate disease and resistance through several protein families that perceive hormones within the nucleus and lead to massive gene induction responses often achieved by de-repression. This review highlights recent advances in our understanding of positive and negative regulators of these hormones signaling pathways that are crucial regulatory targets of hormonal crosstalk in disease and defense. We focus on the most recent discoveries on the jasmonate and salicylate pathway components that explain their crosstalk with other hormonal pathways in the nucleus. We discuss how these components fine-tune defense responses to build a robust plant immune system against a great number of different microbes and, finally, we summarize recent discoveries on specific nuclear hormonal manipulation by microbes which exemplify the ingenious ways by which pathogens can take control over the plant’s hormone signaling network to promote disease.

  7. Comparative Transcriptomics Reveals Jasmonic Acid-Associated Metabolism Related to Cotton Fiber Initiation.

    Liman Wang

    Full Text Available Analysis of mutants and gene expression patterns provides a powerful approach for investigating genes involved in key stages of plant fiber development. In this study, lintless-fuzzless XinWX and linted-fuzzless XinFLM with a single genetic locus difference for lint were used to identify differentially expressed genes. Scanning electron microscopy showed fiber initiation in XinFLM at 0 days post anthesis (DPA. Fiber transcriptional profiling of the lines at three initiation developmental stages (-1, 0, 1 DPA was performed using an oligonucleotide microarray. Loop comparisons of the differentially expressed genes within and between the lines was carried out, and functional classification and enrichment analysis showed that gene expression patterns during fiber initiation were heavily associated with hormone metabolism, transcription factor regulation, lipid transport, and asparagine biosynthetic processes, as previously reported. Further, four members of the allene-oxide cyclase (AOC family that function in jasmonate biosynthesis were parallel up-regulation in fiber initiation, especially at -1 DPA, compared to other tissues and organs in linted-fuzzed TM-1. Real time-quantitative PCR (RT-qPCR analysis in different fiber mutant lines revealed that AOCs were up-regulated higher at -1 DPA in lintless-fuzzless than that in linted-fuzzless and linted-fuzzed materials, and transcription of the AOCs was increased under jasmonic acid (JA treatment. Expression analysis of JA biosynthesis-associated genes between XinWX and XinFLM showed that they were up-regulated during fiber initiation in the fuzzless-lintless mutant. Taken together, jasmonic acid-associated metabolism was related to cotton fiber initiation. Parallel up-regulation of AOCs expression may be important for normal fiber initiation development, while overproduction of AOCs might disrupt normal fiber development.

  8. The effects of surface-applied jasmonic and salicylic acids on caterpillar growth and damage to tomato plants

    Aaron L. Iverson; Louis R. Iverson; Steve Eshita

    2001-01-01

    We tested the role of salicylic acid (SA) and jasmonic acid (JA) in altering the tomato plant's defense against herbivory by tobacco hornworm. Treatments of SA or JA were topically applied to tomato plants, hornworm consumption was allowed to proceed for 12 days, and harvest analyses were performed Measurements taken included a subjective plant rating (1-10 score...

  9. Hexanoic acid is a resistance inducer that protects tomato plants against Pseudomonas syringae by priming the jasmonic acid and salicylic acid pathways.

    Scalschi, Loredana; Vicedo, Begonya; Camañes, Gemma; Fernandez-Crespo, Emma; Lapeña, Leonor; González-Bosch, Carmen; García-Agustín, Pilar

    2013-05-01

    Hexanoic acid-induced resistance (Hx-IR) is effective against several pathogens in tomato plants. Our study of the mechanisms implicated in Hx-IR against Pseudomonas syringae pv. tomato DC3000 suggests that hexanoic acid (Hx) treatment counteracts the negative effect of coronatine (COR) and jasmonyl-isoleucine (JA-Ile) on the salicylic acid (SA) pathway. In Hx-treated plants, an increase in the expression of jasmonic acid carboxyl methyltransferase (JMT) and the SA marker genes PR1 and PR5 indicates a boost in this signalling pathway at the expense of a decrease in JA-Ile. Moreover, Hx treatment potentiates 12-oxo-phytodienoic acid accumulation, which suggests that this molecule might play a role per se in Hx-IR. These results support a positive relationship between the SA and JA pathways in Hx-primed plants. Furthermore, one of the mechanisms of virulence mediated by COR is stomatal re-opening on infection with P. syringae. In this work, we observed that Hx seems to inhibit stomatal opening in planta in the presence of COR, which suggests that, on infection in tomato, this treatment suppresses effector action to prevent bacterial entry into the mesophyll. © 2012 BSPP AND BLACKWELL PUBLISHING LTD.

  10. The DELLA Protein SLR1 Integrates and Amplifies Salicylic Acid- and Jasmonic Acid-Dependent Innate Immunity in Rice1

    De Vleesschauwer, David; Seifi, Hamed Soren; Haeck, Ashley; Huu, Son Nguyen; Demeestere, Kristof

    2016-01-01

    Gibberellins are a class of tetracyclic plant hormones that are well known to promote plant growth by inducing the degradation of a class of nuclear growth-repressing proteins, called DELLAs. In recent years, GA and DELLAs are also increasingly implicated in plant responses to pathogen attack, although our understanding of the underlying mechanisms is still limited, especially in monocotyledonous crop plants. Aiming to further decipher the molecular underpinnings of GA- and DELLA-modulated plant immunity, we studied the dynamics and impact of GA and DELLA during infection of the model crop rice (Oryza sativa) with four different pathogens exhibiting distinct lifestyles and infection strategies. Opposite to previous findings in Arabidopsis (Arabidopsis thaliana), our findings reveal a prominent role of the DELLA protein Slender Rice1 (SLR1) in the resistance toward (hemi)biotrophic but not necrotrophic rice pathogens. Moreover, contrary to the differential effect of DELLA on the archetypal defense hormones salicylic acid (SA) and jasmonic acid (JA) in Arabidopsis, we demonstrate that the resistance-promoting effect of SLR1 is due at least in part to its ability to boost both SA- and JA-mediated rice defenses. In a reciprocal manner, we found JA and SA treatment to interfere with GA metabolism and stabilize SLR1. Together, these findings favor a model whereby SLR1 acts as a positive regulator of hemibiotroph resistance in rice by integrating and amplifying SA- and JA-dependent defense signaling. Our results highlight the differences in hormone defense networking between rice and Arabidopsis and underscore the importance of GA and DELLA in molding disease outcomes. PMID:26829979

  11. The DELLA Protein SLR1 Integrates and Amplifies Salicylic Acid- and Jasmonic Acid-Dependent Innate Immunity in Rice.

    De Vleesschauwer, David; Seifi, Hamed Soren; Filipe, Osvaldo; Haeck, Ashley; Huu, Son Nguyen; Demeestere, Kristof; Höfte, Monica

    2016-03-01

    Gibberellins are a class of tetracyclic plant hormones that are well known to promote plant growth by inducing the degradation of a class of nuclear growth-repressing proteins, called DELLAs. In recent years, GA and DELLAs are also increasingly implicated in plant responses to pathogen attack, although our understanding of the underlying mechanisms is still limited, especially in monocotyledonous crop plants. Aiming to further decipher the molecular underpinnings of GA- and DELLA-modulated plant immunity, we studied the dynamics and impact of GA and DELLA during infection of the model crop rice (Oryza sativa) with four different pathogens exhibiting distinct lifestyles and infection strategies. Opposite to previous findings in Arabidopsis (Arabidopsis thaliana), our findings reveal a prominent role of the DELLA protein Slender Rice1 (SLR1) in the resistance toward (hemi)biotrophic but not necrotrophic rice pathogens. Moreover, contrary to the differential effect of DELLA on the archetypal defense hormones salicylic acid (SA) and jasmonic acid (JA) in Arabidopsis, we demonstrate that the resistance-promoting effect of SLR1 is due at least in part to its ability to boost both SA- and JA-mediated rice defenses. In a reciprocal manner, we found JA and SA treatment to interfere with GA metabolism and stabilize SLR1. Together, these findings favor a model whereby SLR1 acts as a positive regulator of hemibiotroph resistance in rice by integrating and amplifying SA- and JA-dependent defense signaling. Our results highlight the differences in hormone defense networking between rice and Arabidopsis and underscore the importance of GA and DELLA in molding disease outcomes. © 2016 American Society of Plant Biologists. All Rights Reserved.

  12. Meristem maintenance, auxin, jasmonic and abscisic acid pathways as a mechanism for phenotypic plasticity in Antirrhinum majus

    Weiss, Julia; Alcantud-Rodriguez, Raquel; Toksöz, Tugba; Egea-Cortines, Marcos

    2016-01-01

    Plants grow under climatic changing conditions that cause modifications in vegetative and reproductive development. The degree of changes in organ development i.e. its phenotypic plasticity seems to be determined by the organ identity and the type of environmental cue. We used intraspecific competition and found that Antirrhinum majus behaves as a decoupled species for lateral organ size and number. Crowding causes decreases in leaf size and increased leaf number whereas floral size is robust and floral number is reduced. Genes involved in shoot apical meristem maintenance like ROA and HIRZ, cell cycle (CYCD3a; CYCD3b, HISTONE H4) or organ polarity (GRAM) were not significantly downregulated under crowding conditions. A transcriptomic analysis of inflorescence meristems showed Gene Ontology enriched pathways upregulated including Jasmonic and Abscisic acid synthesis and or signalling. Genes involved in auxin synthesis such as AmTAR2 and signalling AmANT were not affected by crowding. In contrast, AmJAZ1, AmMYB21, AmOPCL1 and AmABA2 were significantly upregulated. Our work provides a mechanistic working hypothesis where a robust SAM and stable auxin signalling enables a homogeneous floral size while changes in JA and ABA signalling maybe responsible for the decreased leaf size and floral number.

  13. UV-C-Induced alleviation of transcriptional gene silencing through plant–plant communication: Key roles of jasmonic acid and salicylic acid pathways

    Xu, Wei; Wang, Ting [Key Laboratory of Ion Beam Bio-engineering, Hefei Institutes of Physical Science, Chinese Academy of Sciences, P.O. Box 1138, Hefei, Anhui, 230031 (China); Xu, Shaoxin [School of physics and materials science, Anhui University, Hefei, Anhui, 230601 (China); Li, Fanghua; Deng, Chenguang; Wu, Lijun; Wu, Yuejin [Key Laboratory of Ion Beam Bio-engineering, Hefei Institutes of Physical Science, Chinese Academy of Sciences, P.O. Box 1138, Hefei, Anhui, 230031 (China); Bian, Po, E-mail: bianpo@ipp.ac.cn [Key Laboratory of Ion Beam Bio-engineering, Hefei Institutes of Physical Science, Chinese Academy of Sciences, P.O. Box 1138, Hefei, Anhui, 230031 (China)

    2016-08-15

    Highlights: • Transcriptional gene silencing (TGS) in plants can be epigenetically alleviated by volatile signals from UV-C- irradiated neighboring plants. • Alleviation of TGS can be induced by UV-C irradiation through plant–plant–plant communication. • JA and SA signals take part in interplant communication for alleviation of TGS. - Abstract: Plant stress responses at the epigenetic level are expected to allow more permanent changes of gene expression and potentially long-term adaptation. While it has been reported that plants subjected to adverse environments initiate various stress responses in their neighboring plants, little is known regarding epigenetic responses to external stresses mediated by plant–plant communication. In this study, we show that DNA repetitive elements of Arabidopsis thaliana, whose expression is inhibited epigenetically by transcriptional gene silencing (TGS) mechanism, are activated by UV-C irradiation through airborne plant–plant and plant–plant–plant communications, accompanied by DNA demethylation at CHH sites. Moreover, the TGS is alleviated by direct treatments with exogenous methyl jasmonate (MeJA) and methyl salicylate (MeSA). Further, the plant–plant and plant–plant–plant communications are blocked by mutations in the biosynthesis or signaling of jasmonic acid (JA) or salicylic acid (SA), indicating that JA and SA pathways are involved in the interplant communication for epigenetic responses. For the plant–plant–plant communication, stress cues are relayed to the last set of receiver plants by promoting the production of JA and SA signals in relaying plants, which exhibit upregulated expression of genes for JA and SA biosynthesis and enhanced emanation of MeJA and MeSA.

  14. UV-C-Induced alleviation of transcriptional gene silencing through plant–plant communication: Key roles of jasmonic acid and salicylic acid pathways

    Xu, Wei; Wang, Ting; Xu, Shaoxin; Li, Fanghua; Deng, Chenguang; Wu, Lijun; Wu, Yuejin; Bian, Po

    2016-01-01

    Highlights: • Transcriptional gene silencing (TGS) in plants can be epigenetically alleviated by volatile signals from UV-C- irradiated neighboring plants. • Alleviation of TGS can be induced by UV-C irradiation through plant–plant–plant communication. • JA and SA signals take part in interplant communication for alleviation of TGS. - Abstract: Plant stress responses at the epigenetic level are expected to allow more permanent changes of gene expression and potentially long-term adaptation. While it has been reported that plants subjected to adverse environments initiate various stress responses in their neighboring plants, little is known regarding epigenetic responses to external stresses mediated by plant–plant communication. In this study, we show that DNA repetitive elements of Arabidopsis thaliana, whose expression is inhibited epigenetically by transcriptional gene silencing (TGS) mechanism, are activated by UV-C irradiation through airborne plant–plant and plant–plant–plant communications, accompanied by DNA demethylation at CHH sites. Moreover, the TGS is alleviated by direct treatments with exogenous methyl jasmonate (MeJA) and methyl salicylate (MeSA). Further, the plant–plant and plant–plant–plant communications are blocked by mutations in the biosynthesis or signaling of jasmonic acid (JA) or salicylic acid (SA), indicating that JA and SA pathways are involved in the interplant communication for epigenetic responses. For the plant–plant–plant communication, stress cues are relayed to the last set of receiver plants by promoting the production of JA and SA signals in relaying plants, which exhibit upregulated expression of genes for JA and SA biosynthesis and enhanced emanation of MeJA and MeSA.

  15. An allene oxide and 12-oxophytodienoic acid are key intermediates in jasmonic acid biosynthesis by Fusarium oxysporum.

    Oliw, Ernst H; Hamberg, Mats

    2017-08-01

    Fungi can produce jasmonic acid (JA) and its isoleucine conjugate in large quantities, but little is known about the biosynthesis. Plants form JA from 18:3 n -3 by 13 S -lipoxygenase (LOX), allene oxide synthase, and allene oxide cyclase. Shaking cultures of Fusarium oxysporum f. sp. tulipae released over 200 mg of jasmonates per liter. Nitrogen powder of the mycelia expressed 10 R -dioxygenase-epoxy alcohol synthase activities, which was confirmed by comparison with the recombinant enzyme. The 13 S -LOX of F. oxysporum could not be detected in the cell-free preparations. Incubation of mycelia in phosphate buffer with [17,17,18,18,18- 2 H 5 ]18:3 n -3 led to biosynthesis of a [ 2 H 5 ]12-oxo-13-hydroxy-9 Z ,15 Z -octadecadienoic acid (α-ketol), [ 2 H 5 ]12-oxo-10,15 Z -phytodienoic acid (12-OPDA), and [ 2 H 5 ]13-keto- and [ 2 H 5 ]13 S -hydroxyoctadecatrienoic acids. The α-ketol consisted of 90% of the 13 R stereoisomer, suggesting its formation by nonenzymatic hydrolysis of an allene oxide with 13 S configuration. Labeled and unlabeled 12-OPDA were observed following incubation with 0.1 mM [ 2 H 5 ]18:3 n -3 in a ratio from 0.4:1 up to 47:1 by mycelia of liquid cultures of different ages, whereas 10 times higher concentration of [ 2 H 5 ]13 S -hydroperoxyoctadecatrienoic acid was required to detect biosynthesis of [ 2 H 5 ]12-OPDA. The allene oxide is likely formed by a cytochrome P450 or catalase-related hydroperoxidase. We conclude that F. oxysporum , like plants, forms jasmonates with an allene oxide and 12-OPDA as intermediates. Copyright © 2017 by the American Society for Biochemistry and Molecular Biology, Inc.

  16. Jasmonic acid carboxyl methyltransferase regulates development and herbivory-induced defense response in rice.

    Qi, Jinfeng; Li, Jiancai; Han, Xiu; Li, Ran; Wu, Jianqiang; Yu, Haixin; Hu, Lingfei; Xiao, Yutao; Lu, Jing; Lou, Yonggen

    2016-06-01

    Jasmonic acid (JA) and related metabolites play a key role in plant defense and growth. JA carboxyl methyltransferase (JMT) may be involved in plant defense and development by methylating JA to methyl jasmonate (MeJA) and thus influencing the concentrations of JA and related metabolites. However, no JMT gene has been well characterized in monocotyledon defense and development at the molecular level. After we cloned a rice JMT gene, OsJMT1, whose encoding protein was localized in the cytosol, we found that the recombinant OsJMT1 protein catalyzed JA to MeJA. OsJMT1 is up-regulated in response to infestation with the brown planthopper (BPH; Nilaparvata lugens). Plants in which OsJMT1 had been overexpressed (oe-JMT plants) showed reduced height and yield. These oe-JMT plants also exhibited increased MeJA levels but reduced levels of herbivore-induced JA and jasmonoyl-isoleucine (JA-Ile). The oe-JMT plants were more attractive to BPH female adults but showed increased resistance to BPH nymphs, probably owing to the different responses of BPH female adults and nymphs to the changes in levels of H2 O2 and MeJA in oe-JMT plants. These results indicate that OsJMT1, by altering levels of JA and related metabolites, plays a role in regulating plant development and herbivore-induced defense responses in rice. © 2015 Institute of Botany, Chinese Academy of Sciences.

  17. Salicylic acid signaling inhibits apoplastic reactive oxygen species signaling.

    Xu, Enjun; Brosché, Mikael

    2014-06-04

    Reactive oxygen species (ROS) are used by plants as signaling molecules during stress and development. Given the amount of possible challenges a plant face from their environment, plants need to activate and prioritize between potentially conflicting defense signaling pathways. Until recently, most studies on signal interactions have focused on phytohormone interaction, such as the antagonistic relationship between salicylic acid (SA)-jasmonic acid and cytokinin-auxin. In this study, we report an antagonistic interaction between SA signaling and apoplastic ROS signaling. Treatment with ozone (O3) leads to a ROS burst in the apoplast and induces extensive changes in gene expression and elevation of defense hormones. However, Arabidopsis thaliana dnd1 (defense no death1) exhibited an attenuated response to O3. In addition, the dnd1 mutant displayed constitutive expression of defense genes and spontaneous cell death. To determine the exact process which blocks the apoplastic ROS signaling, double and triple mutants involved in various signaling pathway were generated in dnd1 background. Simultaneous elimination of SA-dependent and SA-independent signaling components from dnd1 restored its responsiveness to O3. Conversely, pre-treatment of plants with SA or using mutants that constitutively activate SA signaling led to an attenuation of changes in gene expression elicited by O3. Based upon these findings, we conclude that plants are able to prioritize the response between ROS and SA via an antagonistic action of SA and SA signaling on apoplastic ROS signaling.

  18. Exogenous application of methyl jasmonate and salicylic acid on citrus foliage: Effecs on foliar volatiles and aggregation behavior of Asian citrus psyllid (Diaphorina citri)

    Methyl jasmonate (MeJA) and salicylic acid (SA) are well-known activators of chemical defenses in plants. The SA pathway is involved in citrus response to infection by Candidatus Liberibacter asiaticus (CLas); less is known about the role of jasmonates in citrus defense response. We examined the eff...

  19. Jasmonic acid is a key regulator of spider mite-induced volatile terpenoid and methyl salicylate emission in tomato

    Ament, K.; Kant, M.R.; Sabelis, M.W.; Haring, M.A.; Schuurink, R.C.

    2004-01-01

    The tomato (Lycopersicon esculentum) mutant def-1, which is deficient in induced jasmonic acid (JA) accumulation upon wounding or herbivory, was used to study the role of JA in the direct and indirect defense responses to phytophagous mites (Tetranychus urticae). In contrast to earlier reports,

  20. Effect of methyl jasmonate, salicylic acid, Headline and Stadium on root yield, sucrose yield, and storage properties

    Methyl jasmonate (MeJA) and salicylic acid (SA) have been reported to enhance yield and protect crop plants and products against abiotic stresses and diseases. The effect of these compounds on sugarbeets, however, is unknown. Research was conducted in 2016 and 2017 to investigate the effects of an e...

  1. Plants know where it hurts: root and shoot jasmonic acid induction elicit differential responses in Brassica oleracea.

    Tom O G Tytgat

    Full Text Available Plants respond to herbivore attack by rapidly inducing defenses that are mainly regulated by jasmonic acid (JA. Due to the systemic nature of induced defenses, attack by root herbivores can also result in a shoot response and vice versa, causing interactions between above- and belowground herbivores. However, little is known about the molecular mechanisms underlying these interactions. We investigated whether plants respond differently when roots or shoots are induced. We mimicked herbivore attack by applying JA to the roots or shoots of Brassica oleracea and analyzed molecular and chemical responses in both organs. In shoots, an immediate and massive change in primary and secondary metabolism was observed. In roots, the JA-induced response was less extensive and qualitatively different from that in the shoots. Strikingly, in both roots and shoots we also observed differential responses in primary metabolism, development as well as defense specific traits depending on whether the JA induction had been below- or aboveground. We conclude that the JA response is not only tissue-specific but also dependent on the organ that was induced. Already very early in the JA signaling pathway the differential response was observed. This indicates that both organs have a different JA signaling cascade, and that the signal eliciting systemic responses contains information about the site of induction, thus providing plants with a mechanism to tailor their responses specifically to the organ that is damaged.

  2. Study on the extraction, purification and quantification of jasmonic acid, abscisic acid and indole-3-acetic acid in plants.

    Zhang, Feng Juan; Jin, You Ju; Xu, Xing You; Lu, Rong Chun; Chen, Hua Jun

    2008-01-01

    Jasmonic acid (JA), abscisic acid (ABA) and indole-3-acetic acid (IAA) are important plant hormones. Plant hormones are difficult to analyse because they occur in small concentrations and other substances in the plant interfere with their detection. To develop a new, inexpensive procedure for the rapid extraction and purification of IAA, ABA and JA from various plant species. Samples were prepared by extraction of plant tissues with methanol and ethyl acetate. Then the extracts were further purified and enriched with C(18) cartridges. The final extracts were derivatised with diazomethane and then measured by GC-MS. The results of the new methodology were compared with those of the Creelman and Mullet procedure. Sequential elution of the assimilates from the C(18 )cartridges revealed that IAA and ABA eluted in 40% methanol, while JA subsequently eluted in 60% methanol. The new plant hormone extraction and purification procedure produced results that were comparable to those obtained with the Creelman and Mullet's procedure. This new procedure requires only 0.5 g leaf samples to quantify these compounds with high reliability and can simultaneously determine the concentrations of the three plant hormones. A simple, inexpensive method was developed for determining endogenous IAA, ABA and JA concentrations in plant tissue.

  3. Pathogen exploitation of an abscisic acid- and jasmonate-inducible MAPK phosphatase and its interception by Arabidopsis immunity.

    Mine, Akira; Berens, Matthias L; Nobori, Tatsuya; Anver, Shajahan; Fukumoto, Kaori; Winkelmüller, Thomas M; Takeda, Atsushi; Becker, Dieter; Tsuda, Kenichi

    2017-07-11

    Phytopathogens promote virulence by, for example, exploiting signaling pathways mediated by phytohormones such as abscisic acid (ABA) and jasmonate (JA). Some plants can counteract pathogen virulence by invoking a potent form of immunity called effector-triggered immunity (ETI). Here, we report that ABA and JA mediate inactivation of the immune-associated MAP kinases (MAPKs), MPK3 and MPK6, in Arabidopsis thaliana ABA induced expression of genes encoding the protein phosphatases 2C (PP2Cs), HAI1 , HAI2 , and HAI3 through ABF/AREB transcription factors. These three HAI PP2Cs interacted with MPK3 and MPK6 and were required for ABA-mediated MPK3/MPK6 inactivation and immune suppression. The bacterial pathogen Pseudomonas syringae pv. tomato ( Pto ) DC3000 activates ABA signaling and produces a JA-mimicking phytotoxin, coronatine (COR), that promotes virulence. We found that Pto DC3000 induces HAI1 through COR-mediated activation of MYC2, a master transcription factor in JA signaling. HAI1 dephosphorylated MPK3 and MPK6 in vitro and was necessary for COR-mediated suppression of MPK3/MPK6 activation and immunity. Intriguingly, upon ETI activation, A. thaliana plants overcame the HAI1-dependent virulence of COR by blocking JA signaling. Finally, we showed conservation of induction of HAI PP2Cs by ABA and JA in other Brassicaceae species. Taken together, these results suggest that ABA and JA signaling pathways, which are hijacked by the bacterial pathogen, converge on the HAI PP2Cs that suppress activation of the immune-associated MAPKs. Also, our data unveil interception of JA-signaling activation as a host counterstrategy against the bacterial suppression of MAPKs during ETI.

  4. Induction of direct and indirect plant responses by jasmonic acid, low spider mite densities, or a combination of jasmonic acid treatment and spider mite infestation.

    Gols, Rieta; Roosjen, Mara; Dijkman, Herman; Dicke, Marcel

    2003-12-01

    Jasmonic acid (JA) and the octadecanoid pathway are involved in both induced direct and induced indirect plant responses. In this study, the herbivorous mite, Tetranychus urticae, and its predator, Phytoseiulus persimilis, were given a choice between Lima bean plants induced by JA or spider mites and uninduced control plants. Infestation densities resulting in the induction of predator attractants were much lower than thus far assumed, i.e., predatory mites were significantly attracted to plants that were infested for 2 days with only one or four spider mites per plant. Phytoseiulus persimilis showed a density-dependent response to volatiles from plants that were infested with different numbers of spider mites. Similarly, treating plants with increasing concentrations of JA also led to increased attraction of P. persimilis. Moreover, the duration of spider mite infestation was positively correlated with the proportion of predators that were attracted to mite-infested plants. A pretreatment of the plants with JA followed by a spider mite infestation enhanced the attraction of P. persimilis to plant volatiles compared to attraction to volatiles from plants that were only infested with spider mites and did not receive a pretreatment with JA. The herbivore, T. urticae preferred leaf tissue that previously had been infested with conspecifics to uninfested leaf tissue. In the case of choice tests with JA-induced and control leaf tissue, spider mites slightly preferred control leaf tissue. When spider mites were given a choice between leaf discs induced by JA and leaf discs damaged by spider mite feeding, they preferred the latter. The presence of herbivore induced chemicals and/or spider mite products enhanced settlement of the mites, whereas treatment with JA seemed to impede settlement.

  5. Enhanced daidzin production from jasmonic and acetyl salicylic acid elicited hairy root cultures of Psoralea corylifolia L. (Fabaceae).

    Zaheer, Mohd; Reddy, Vudem Dashavantha; Giri, Charu Chandra

    2016-07-01

    Daidzin (7-O-glucoside of daidzein) has several pharmacological benefits in herbal remedy, as antioxidant and shown antidipsotropic activity. Hairy root culture of Psoralea corylifolia L. was developed for biomass and enhanced daidzin production using signalling compounds such as jasmonic acid (JA) and acetyl salicylic acid (ASA). Best response of 2.8-fold daidzin (5.09% DW) with 1 μM JA treatment after second week and 7.3-fold (3.43% DW) with 10 μM JA elicitation after 10th week was obtained from hairy roots compared to untreated control. ASA at 10 μM promoted 1.7-fold increase in daidzin (1.49% DW) content after seventh week compared to control (0.83% DW). Addition of 25 μM ASA resulted in 1.44% DW daidzin (1.5-fold increase) with 0.91% DW in control after fifth week and 1.44% DW daidzin (2.3-fold increase) after eighth week when compared to untreated control (0.62% DW). Reduced biomass with increased daidzin content was facilitated by elicited hairy root cultures.

  6. Interactions between the jasmonic and salicylic acid pathway modulate the plant metabolome and affect herbivores of different feeding types.

    Schweiger, R; Heise, A-M; Persicke, M; Müller, C

    2014-07-01

    The phytohormones jasmonic acid (JA) and salicylic acid (SA) mediate induced plant defences and the corresponding pathways interact in a complex manner as has been shown on the transcript and proteine level. Downstream, metabolic changes are important for plant-herbivore interactions. This study investigated metabolic changes in leaf tissue and phloem exudates of Plantago lanceolata after single and combined JA and SA applications as well as consequences on chewing-biting (Heliothis virescens) and piercing-sucking (Myzus persicae) herbivores. Targeted metabolite profiling and untargeted metabolic fingerprinting uncovered different categories of plant metabolites, which were influenced in a specific manner, indicating points of divergence, convergence, positive crosstalk and pronounced mutual antagonism between the signaling pathways. Phytohormone-specific decreases of primary metabolite pool sizes in the phloem exudates may indicate shifts in sink-source relations, resource allocation, nutrient uptake or photosynthesis. Survival of both herbivore species was significantly reduced by JA and SA treatments. However, the combined application of JA and SA attenuated the negative effects at least against H. virescens suggesting that mutual antagonism between the JA and SA pathway may be responsible. Pathway interactions provide a great regulatory potential for the plant that allows triggering of appropriate defences when attacked by different antagonist species. © 2013 John Wiley & Sons Ltd.

  7. Perception of low red:far-red ratio comprises both salicylic acid- and jasmonic acid-dependent pathogen defences in Arabidopsis

    De Wit, M. de; Spoel, S.H.; Sanchez-Perez, G.F.; Gommers, C.M.M.; Pieterse, C.M.J.; Voesenek, L.A.C.J.; Pierik, R.

    2013-01-01

    In dense stands of plants, such as agricultural monocultures, plants are exposed simultaneously to competition for light and other stresses such as pathogen infection. Here, we show that both salicylic acid (SA)-dependent and jasmonic acid (JA)-dependent disease resistance is inhibited by a

  8. Different mechanisms of Trichoderma virens-mediated resistance in tomato against Fusarium wilt involve the jasmonic and salicylic acid pathways.

    Jogaiah, Sudisha; Abdelrahman, Mostafa; Tran, Lam-Son Phan; Ito, Shin-Ichi

    2018-04-01

    In the present study, we investigated the role of Trichoderma virens (TriV_JSB100) spores or cell-free culture filtrate in the regulation of growth and activation of the defence responses of tomato (Solanum lycopersicum) plants against Fusarium oxysporum f. sp. lycopersici by the development of a biocontrol-plant-pathogen interaction system. Two-week-old tomato seedlings primed with TriV_JSB100 spores cultured on barley grains (BGS) or with cell-free culture filtrate (CF) were inoculated with Fusarium pathogen under glasshouse conditions; this resulted in significantly lower disease incidence in tomato Oogata-Fukuju plants treated with BGS than in those treated with CF. To dissect the pathways associated with this response, jasmonic acid (JA) and salicylic acid (SA) signalling in BGS- and CF-induced resistance was evaluated using JA- and SA-impaired tomato lines. We observed that JA-deficient mutant def1 plants were susceptible to Fusarium pathogen when they were treated with BGS. However, wild-type (WT) BGS-treated tomato plants showed a higher JA level and significantly lower disease incidence. SA-deficient mutant NahG plants treated with CF were also found to be susceptible to Fusarium pathogen and displayed low SA levels, whereas WT CF-treated tomato plants exhibited moderately lower disease levels and substantially higher SA levels. Expression of the JA-responsive defensin gene PDF1 was induced in WT tomato plants treated with BGS, whereas the SA-inducible pathogenesis-related protein 1 acidic (PR1a) gene was up-regulated in WT tomato plants treated with CF. These results suggest that TriV_JSB100 BGS and CF differentially induce JA and SA signalling cascades for the elicitation of Fusarium oxysporum resistance in tomato. © 2017 BSPP AND JOHN WILEY & SONS LTD.

  9. The Epiphytic Fungus Pseudozyma aphidis Induces Jasmonic Acid- and Salicylic Acid/Nonexpressor of PR1-Independent Local and Systemic Resistance1[C][W

    Buxdorf, Kobi; Rahat, Ido; Gafni, Aviva; Levy, Maggie

    2013-01-01

    Pseudozyma spp. are yeast-like fungi, classified in the Ustilaginales, which are mostly epiphytic or saprophytic and are not pathogenic to plants. Several Pseudozyma species have been reported to exhibit biological activity against powdery mildews. However, previous studies have reported that Pseudozyma aphidis, which can colonize plant surfaces, is not associated with the ‎‎collapse of powdery ‎mildew colonies. In this report, we describe a novel P. aphidis strain and study its interactions with its plant host and the plant pathogen Botrytis cinerea. This isolate was found to secrete extracellular metabolites that inhibit various fungal pathogens in vitro and significantly reduce B. cinerea infection in vivo. Moreover, P. aphidis sensitized Arabidopsis (Arabidopsis thaliana) plants’ defense machinery via local and systemic induction of PATHOGENESIS-RELATED1 (PR1) and PLANT DEFENSIN1.2 (PDF1.2) expression. P. aphidis also reduced B. cinerea infection, locally and systemically, in Arabidopsis mutants impaired in jasmonic acid (JA) or salicylic acid (SA) signaling. Thus, in addition to direct inhibition, P. aphidis may inhibit B. cinerea infection via induced resistance in a manner independent of SA, JA, and Nonexpressor of PR1 (NPR1). P. aphidis primed the plant defense machinery and induced stronger activation of PDF1.2 after B. cinerea infection. Finally, P. aphidis fully or partially reconstituted PR1 and PDF1.2 expression in npr1-1 mutant and in plants with the SA hydroxylase NahG transgene, but not in a jasmonate resistant1-1 mutant, after B. cinerea infection, suggesting that P. aphidis can bypass the SA/NPR1, but not JA, pathway to activate PR genes. Thus, either partial gene activation is sufficient to induce resistance, or the resistance is not directed solely through PR1 and PDF1.2 but probably through other pathogen-resistance genes or pathways as well. PMID:23388119

  10. The epiphytic fungus Pseudozyma aphidis induces jasmonic acid- and salicylic acid/nonexpressor of PR1-independent local and systemic resistance.

    Buxdorf, Kobi; Rahat, Ido; Gafni, Aviva; Levy, Maggie

    2013-04-01

    Pseudozyma spp. are yeast-like fungi, classified in the Ustilaginales, which are mostly epiphytic or saprophytic and are not pathogenic to plants. Several Pseudozyma species have been reported to exhibit biological activity against powdery mildews. However, previous studies have reported that Pseudozyma aphidis, which can colonize plant surfaces, is not associated with the collapse of powdery mildew colonies. In this report, we describe a novel P. aphidis strain and study its interactions with its plant host and the plant pathogen Botrytis cinerea. This isolate was found to secrete extracellular metabolites that inhibit various fungal pathogens in vitro and significantly reduce B. cinerea infection in vivo. Moreover, P. aphidis sensitized Arabidopsis (Arabidopsis thaliana) plants' defense machinery via local and systemic induction of pathogenesis-related1 (PR1) and plant defensin1.2 (PDF1.2) expression. P. aphidis also reduced B. cinerea infection, locally and systemically, in Arabidopsis mutants impaired in jasmonic acid (JA) or salicylic acid (SA) signaling. Thus, in addition to direct inhibition, P. aphidis may inhibit B. cinerea infection via induced resistance in a manner independent of SA, JA, and Nonexpressor of PR1 (NPR1). P. aphidis primed the plant defense machinery and induced stronger activation of PDF1.2 after B. cinerea infection. Finally, P. aphidis fully or partially reconstituted PR1 and PDF1.2 expression in npr1-1 mutant and in plants with the SA hydroxylase NahG transgene, but not in a jasmonate resistant1-1 mutant, after B. cinerea infection, suggesting that P. aphidis can bypass the SA/NPR1, but not JA, pathway to activate PR genes. Thus, either partial gene activation is sufficient to induce resistance, or the resistance is not directed solely through PR1 and PDF1.2 but probably through other pathogen-resistance genes or pathways as well.

  11. The Arabidopsis thaliana lectin receptor kinase LecRK-I.9 is required for full resistance to Pseudomonas syringae and affects jasmonate signalling.

    Balagué, Claudine; Gouget, Anne; Bouchez, Olivier; Souriac, Camille; Haget, Nathalie; Boutet-Mercey, Stéphanie; Govers, Francine; Roby, Dominique; Canut, Hervé

    2017-09-01

    On microbial attack, plants can detect invaders and activate plant innate immunity. For the detection of pathogen molecules or cell wall damage, plants employ receptors that trigger the activation of defence responses. Cell surface proteins that belong to large families of lectin receptor kinases are candidates to function as immune receptors. Here, the function of LecRK-I.9 (At5g60300), a legume-type lectin receptor kinase involved in cell wall-plasma membrane contacts and in extracellular ATP (eATP) perception, was studied through biochemical, gene expression and reverse genetics approaches. In Arabidopsis thaliana, LecRK-I.9 expression is rapidly, highly and locally induced on inoculation with avirulent strains of Pseudomonas syringae pv. tomato (Pst). Two allelic lecrk-I.9 knock-out mutants showed decreased resistance to Pst. Conversely, over-expression of LecRK-I.9 led to increased resistance to Pst. The analysis of defence gene expression suggests an alteration of both the salicylic acid (SA) and jasmonic acid (JA) signalling pathways. In particular, LecRK-I.9 expression during plant-pathogen interaction was dependent on COI1 (CORONATINE INSENSITIVE 1) and JAR1 (JASMONATE RESISTANT 1) components, and JA-responsive transcription factors (TFs) showed altered levels of expression in plants over-expressing LecRK-I.9. A similar misregulation of these TFs was obtained by JA treatment. This study identified LecRK-I.9 as necessary for full resistance to Pst and demonstrated its involvement in the control of defence against pathogens through a regulation of JA signalling components. The role of LecRK-I.9 is discussed with regard to the potential molecular mechanisms linking JA signalling to cell wall damage and/or eATP perception. © 2016 BSPP AND JOHN WILEY & SONS LTD.

  12. Complementary action of jasmonic acid on salicylic acid in mediating fungal elicitor-induced flavonol glycoside accumulation of Ginkgo biloba cells.

    Xu, Maojun; Dong, Jufang; Wang, Huizhong; Huang, Luqi

    2009-08-01

    The antagonistic action between jasmonic acid (JA) and salicylic acid (SA) in plant defence responses has been well documented. However, their relationship in secondary metabolite production is largely unknown. Here, we report that PB90, a protein elicitor from Phytophthora boehmeriae, triggers JA generation, SA accumulation and flavonol glycoside production of Ginkgo biloba cells. JA inhibitors suppress not only PB90-triggered JA generation, but also the elicitor-induced flavonol glycoside production. However, the elicitor can still enhance flavonol glycoside production even though the JA generation is totally inhibited. Over-expression of SA hydrolase gene NahG not only abolishes SA accumulation, but also suppresses the elicitor-induced flavonol glycoside production when JA signalling is inhibited. Interestingly, expression of NahG does not inhibit the elicitor-induced flavonol glycoside accumulation in the absence of JA inhibitors. Moreover, JA levels are significantly enhanced when SA accumulation is impaired in the transgenic cells. Together, the data suggest that both JA and SA are involved in PB90-induced flavonol glycoside production. Furthermore, we demonstrate that JA signalling might be enhanced to substitute for SA to mediate the elicitor-induced flavonol glycoside accumulation when SA signalling is impaired, which reveals an unusual complementary relationship between JA and SA in mediating plant secondary metabolite production.

  13. Shifting from priming of salicylic acid- to jasmonic acid-regulated defences by Trichoderma protects tomato against the root knot nematode Meloidogyne incognita.

    Martínez-Medina, Ainhoa; Fernandez, Ivan; Lok, Gerrit B; Pozo, María J; Pieterse, Corné M J; Van Wees, Saskia C M

    2017-02-01

    Beneficial root endophytes such as Trichoderma spp. can reduce infections by parasitic nematodes through triggering host defences. Little is currently known about the complex hormone signalling underlying the induction of resistance. In this study, we investigated whether Trichoderma modulates the hormone signalling network in the host to induce resistance to nematodes. We investigated the role and the timing of the jasmonic acid (JA)- and salicylic acid (SA)-regulated defensive pathways in Trichoderma-induced resistance to the root knot nematode Meloidogyne incognita. A split-root system of tomato (Solanum lycopersicum) was used to study local and systemic induced defences by analysing nematode performance, defence gene expression, responsiveness to exogenous hormone application, and dependence on SA and JA signalling of Trichoderma-induced resistance. Root colonization by Trichoderma impeded nematode performance both locally and systemically at multiple stages of the parasitism, that is, invasion, galling and reproduction. First, Trichoderma primed SA-regulated defences, which limited nematode root invasion. Then, Trichoderma enhanced JA-regulated defences, thereby antagonizing the deregulation of JA-dependent immunity by the nematodes, which compromised galling and fecundity. Our results show that Trichoderma primes SA- and JA-dependent defences in roots, and that the priming of responsiveness to these hormones upon nematode attack is plastic and adaptive to the parasitism stage. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

  14. Molecular cloning and expression analysis of jasmonic acid dependent but salicylic acid independent LeWRKY1.

    Lu, M; Wang, L F; Du, X H; Yu, Y K; Pan, J B; Nan, Z J; Han, J; Wang, W X; Zhang, Q Z; Sun, Q P

    2015-11-30

    Various plant genes can be activated or inhibited by phytohormones under conditions of biotic and abiotic stress, especially in response to jasmonic acid (JA) and salicylic acid (SA). Interactions between JA and SA may be synergistic or antagonistic, depending on the stress condition. In this study, we cloned a full-length cDNA (LeWRKY1, GenBank accession No. FJ654265) from Lycopersicon esculentum by rapid amplification of cDNA ends. Sequence analysis showed that this gene is a group II WRKY transcription factor. Analysis of LeWRKY1 mRNA expression in various tissues by qRT-PCR showed that the highest and lowest expression occurred in the leaves and stems, respectively. In addition, LeWRKY1 expression was induced by JA and Botrytis cinerea Pers., but not by SA.

  15. Inhibitory effect of jasmonic acid and ethylene on epicotyl growth and bud induction in the maritime pine, Pinus pinaster Soland. in ait.

    Martin, Maria Teresa; Pedranzani, Hilda; García-Molinero, Patricia; Pando, Valentin; Sierra-de-Grado, Rosario

    2009-12-01

    Two independent parameters, epicotyl height (cm) and number of induced buds were studied on Pinus pinaster explants to analyse the effects of three phytohormones (6-benzylaminopurine, jasmonic acid, ethylene) which were combined or not in 11 different treatments. Epicotyle length diminished significantly in relation to the control medium (medium without exogen phytohormones) in presence of jasmonic acid, 6-benzylaminopurine or Ethephon (which is converted to ethylene in plants) in any of treatments. Concentrations of 100 microM of jasmonic acid and Ethephon had a greater inhibitory effect than the treatments with 10 microM. In addition to that, jasmonic acid was a stronger inhibitor than Ethephon in any of the tried combinations. There were no significant differences between the control treatment and the treatments with only 10 microM of jasmonic acid or Ethephon. However, 10 microM 6-benzylaminopurine induced bud formation. The different combinations of 6-benzylaminopurine with jasmonic acid and Ethephon showed that concentrations of 10 to 100 microM did not affect the number of induced buds. Jasmonic acid had an inhibitory effect which Ethephon only showed when combined with 100 microM of jasmonic acid and 10 microM of 6-benzylaminopurine. Three response groups were defined by cluster analysis: group 1 produced the greatest mean number of buds (4 to 5) and a mean epicotyl growth of 1 to 1.5 cm; group 2 produced 2 to 4 buds and a mean growth of 0.5 to 1.2 cm; group 3 produced only one bud and a mean epicotyl length of 1.2 to 2 cm.

  16. The effects of abscisic acid, salicylic acid and jasmonic acid on lipid accumulation in two freshwater Chlorella strains.

    Wu, Guanxun; Gao, Zhengquan; Du, Huanmin; Lin, Bin; Yan, Yuchen; Li, Guoqiang; Guo, Yanyun; Fu, Shenggui; Wei, Gongxiang; Wang, Miaomiao; Cui, Meng; Meng, Chunxiao

    2018-03-27

    Sustainable renewable energy is being hotly debated globally because the continued use of finite fossil fuels is now widely recognized as being unsustainable. Microalgae potentially offer great opportunities for resolving this challenge. Abscisic acid (ABA), jasmonic acid (JA) and salicylic acid (SA) are involved in regulating many physiological properties and have been widely used in higher plants. To test if phytohormones have an impact on accumulating lipid for microalgae, ABA, JA and SA were used to induce two Chlorella strains in the present study. The results showed 1.0 mg/L ABA, 10 mg/L SA, and 0.5 mg/L JA, led strain C. vulgaris ZF strain to produce a 45%, 42% and 49% lipid content that was 1.8-, 1.7- and 2.0-fold that of controls, respectively. For FACHB 31 (number 31 of the Freshwater Algae Culture Collection at the Institute of Hydrobiology, Chinese Academy of Sciences), the addition of 1.0 mg/L ABA, 10 mg/L SA, and 0.5 mg/L, JA produced 33%, 30% and 38% lipid content, which was 1.8-, 1.6- and 2.1-fold that of controls, respectively. As for lipid productivity, 1.0 mg/L ABA increased the lipid productivity of C. vulgaris ZF strain and FACHB-31 by 123% and 44%; 10 mg/L SA enhanced lipid productivity by 100% and 33%; the best elicitor, 0.5 mg/L JA, augmented lipid productivity by 127% and 75% compared to that of controls, respectively. The results above suggest that the three phytohormones at physiological concentrations play crucial roles in inducing lipid accumulation in Chlorella.

  17. Jasmonate is essential for insect defense in Arabidopsis

    McConn, Michele; Creelman, Robert A.; Bell, Erin; Mullet, John E.; Browse, John

    1997-01-01

    The signaling pathways that allow plants to mount defenses against chewing insects are known to be complex. To investigate the role of jasmonate in wound signaling in Arabidopsis and to test whether parallel or redundant pathways exist for insect defense, we have studied a mutant (fad3–2 fad7–2 fad8) that is deficient in the jasmonate precursor linolenic acid. Mutant plants contained negligible levels of jasmonate and showed extremely high mortality (≈80%) from attack by larvae of a common saprophagous fungal gnat, Bradysia impatiens (Diptera: Sciaridae), even though neighboring wild-type plants were largely unaffected. Application of exogenous methyl jasmonate substantially protected the mutant plants and reduced mortality to ≈12%. These experiments precisely define the role of jasmonate as being essential for the induction of biologically effective defense in this plant–insect interaction. The transcripts of three wound-responsive genes were shown not to be induced by wounding of mutant plants but the same transcripts could be induced by application of methyl jasmonate. By contrast, measurements of transcript levels for a gene encoding glutathione S-transferase demonstrated that wound induction of this gene is independent of jasmonate synthesis. These results indicate that the mutant will be a good genetic model for testing the practical effectiveness of candidate defense genes. PMID:11038546

  18. Jasmonate is essential for insect defense in Arabidopsis.

    McConn, M; Creelman, R A; Bell, E; Mullet, J E; Browse, J

    1997-05-13

    The signaling pathways that allow plants to mount defenses against chewing insects are known to be complex. To investigate the role of jasmonate in wound signaling in Arabidopsis and to test whether parallel or redundant pathways exist for insect defense, we have studied a mutant (fad3-2 fad7-2 fad8) that is deficient in the jasmonate precursor linolenic acid. Mutant plants contained negligible levels of jasmonate and showed extremely high mortality ( approximately 80%) from attack by larvae of a common saprophagous fungal gnat, Bradysia impatiens (Diptera: Sciaridae), even though neighboring wild-type plants were largely unaffected. Application of exogenous methyl jasmonate substantially protected the mutant plants and reduced mortality to approximately 12%. These experiments precisely define the role of jasmonate as being essential for the induction of biologically effective defense in this plant-insect interaction. The transcripts of three wound-responsive genes were shown not to be induced by wounding of mutant plants but the same transcripts could be induced by application of methyl jasmonate. By contrast, measurements of transcript levels for a gene encoding glutathione S-transferase demonstrated that wound induction of this gene is independent of jasmonate synthesis. These results indicate that the mutant will be a good genetic model for testing the practical effectiveness of candidate defense genes.

  19. Integration of the Pokeweed miRNA and mRNA Transcriptomes Reveals Targeting of Jasmonic Acid-Responsive Genes

    Kira C. M. Neller

    2018-05-01

    Full Text Available The American pokeweed plant, Phytolacca americana, displays broad-spectrum resistance to plant viruses and is a heavy metal hyperaccumulator. However, little is known about the regulation of biotic and abiotic stress responses in this non-model plant. To investigate the control of miRNAs in gene expression, we sequenced the small RNA transcriptome of pokeweed treated with jasmonic acid (JA, a hormone that mediates pathogen defense and stress tolerance. We predicted 145 miRNAs responsive to JA, most of which were unique to pokeweed. These miRNAs were low in abundance and condition-specific, with discrete expression change. Integration of paired mRNA-Seq expression data enabled us to identify correlated, novel JA-responsive targets that mediate hormone biosynthesis, signal transduction, and pathogen defense. The expression of approximately half the pairs was positively correlated, an uncommon finding that we functionally validated by mRNA cleavage. Importantly, we report that a pokeweed-specific miRNA targets the transcript of OPR3, novel evidence that a miRNA regulates a JA biosynthesis enzyme. This first large-scale small RNA study of a Phytolaccaceae family member shows that miRNA-mediated control is a significant component of the JA response, associated with widespread changes in expression of genes required for stress adaptation.

  20. Comparative transcriptional profiling of Gracilariopsis lemaneiformis in response to salicylic acid- and methyl jasmonate-mediated heat resistance.

    Fangjun Wang

    Full Text Available Culturing the economically important macroalga Gracilariopsis lemaneiformis (Rhodophyta is limited due to the high temperatures in the summertime on the southern Chinese coast. Previous studies have demonstrated that two phytohormones, salicylic acid (SA and methyl jasmonate (MJ, can alleviate the adverse effects of high-temperature stress on Gp. lemaneiformis. To elucidate the molecular mechanisms underlying SA- and MJ-mediated heat tolerance, we performed comprehensive analyses of transcriptome-wide gene expression profiles using RNA sequencing (RNA-seq technology. A total of 14,644 unigenes were assembled, and 10,501 unigenes (71.71% were annotated to the reference databases. In the SA, MJ and SA/MJ treatment groups, 519, 830, and 974 differentially expressed unigenes were detected, respectively. Unigenes related to photosynthesis and glycometabolism were enriched by SA, while unigenes associated with glycometabolism, protein synthesis, heat shock and signal transduction were increased by MJ. A crosstalk analysis revealed that 216 genes were synergistically regulated, while 18 genes were antagonistically regulated by SA and MJ. The results indicated that the two phytohormones could mitigate the adverse effects of heat on multiple pathways, and they predominantly acted synergistically to resist heat stress. These results will provide new insights into how SA and MJ modulate the molecular mechanisms that counteract heat stress in algae.

  1. Interplay between Carotenoids, Abscisic Acid and Jasmonate Guides the Compatible Rice-Meloidogyne graminicola Interaction

    Tina Kyndt

    2017-06-01

    Full Text Available In this study, we have characterized the role of carotenoids and chlorophyll in the compatible interaction between the sedentary root knot nematode (RKN Meloidogyne graminicola and the monocot model plant rice (Oryza sativa. Previous transcriptome data showed a differential expression of carotenoid and chlorophyll biosynthesis genes in nematode-induced giant cells and gall tissue. Metabolite measurement showed that galls indeed accumulate chlorophyll a, b and carotenoids, as well as the hormone abscisic acid (ABA. When ABA was externally applied on rice plants, or when ABA-biosynthesis was inhibited, a significant increase in gall formation and nematode development was found, showing the complex role of ABA in this interaction. ABA application suppressed jasmonic acid (JA levels in the plants, while ABA-biosynthesis inhibition lead to increased JA levels confirming an antagonism between ABA and JA in rice roots. In addition, combined applications of ABA and JA showed that the ABA-effect can overcome JA-induced defense. Based on these observations, we hypothesized that the accumulation of chlorophyll and carotenoid precursors would be beneficial to nematode infection. Indeed, when chemically blocking the carotenoid biosynthesis pathway at different steps, which leads to differential accumulation of carotenoids and chlorophyll in the plants, a positive and clear link between accumulation of carotenoids and chlorophyll and rice susceptibility to RKN was detected.

  2. Suppression of jasmonic acid-dependent defense in cotton plant by the mealybug Phenacoccus solenopsis.

    Pengjun Zhang

    Full Text Available The solenopsis mealybug, Phenacoccus solenopsis, has been recently recognized as an aggressively invasive pest in China, and is now becoming a serious threat to the cotton industry in the country. Thus, it is necessary to investigate the molecular mechanisms employed by cotton for defending against P. solenopsis before the pest populations reach epidemic levels. Here, we examined the effects of exogenous jasmonic acid (JA, salicylic acid (SA, and herbivory treatments on feeding behavior and on development of female P. solenopsis. Further, we compared the volatile emissions of cotton plants upon JA, SA, and herbivory treatments, as well as the time-related changes in gossypol production and defense-related genes. Female adult P. solenopsis were repelled by leaves from JA-treated plant, but were not repelled by leaves from SA-treated plants. In contrast, females were attracted by leaves from plants pre-infested by P. solenopsis. The diverse feeding responses by P. solenopsis were due to the difference in volatile emission of plants from different treatments. Furthermore, we show that JA-treated plants slowed P. solenopsis development, but plants pre-infested by P. solenopsis accelerated its development. We also show that P. solenopsis feeding inhibited the JA-regulated gossypol production, and prevented the induction of JA-related genes. We conclude that P. solenopsis is able to prevent the activation of JA-dependent defenses associated with basal resistance to mealybugs.

  3. The COP9 signalosome controls jasmonic acid synthesis and plant responses to herbivory and pathogens.

    Hind, Sarah R; Pulliam, Sarah E; Veronese, Paola; Shantharaj, Deepak; Nazir, Azka; Jacobs, Nekaiya S; Stratmann, Johannes W

    2011-02-01

    The COP9 signalosome (CSN) is a multi-protein complex that regulates the activities of cullin-RING E3 ubiquitin ligases (CRLs). CRLs ubiquitinate proteins in order to target them for proteasomal degradation. The CSN is required for proper plant development. Here we show that the CSN also has a profound effect on plant defense responses. Silencing of genes for CSN subunits in tomato plants resulted in a mild morphological phenotype and reduced expression of wound-responsive genes in response to mechanical wounding, attack by Manduca sexta larvae, and Prosystemin over-expression. In contrast, expression of pathogenesis-related genes was increased in a stimulus-independent manner in these plants. The reduced wound response in CSN-silenced plants corresponded with reduced synthesis of jasmonic acid (JA), but levels of salicylic acid (SA) were unaltered. As a consequence, these plants exhibited reduced resistance against herbivorous M. sexta larvae and the necrotrophic fungal pathogen Botrytis cinerea. In contrast, susceptibility to tobacco mosaic virus (TMV) was not altered in CSN-silenced plants. These data demonstrate that the CSN orchestrates not only plant development but also JA-dependent plant defense responses. © 2011 The Authors. The Plant Journal © 2011 Blackwell Publishing Ltd.

  4. Selective enhancement of scopadulcic acid B production in the cultured tissues of Scoparia dulcis by methyl jasmonate.

    Nkembo, Kasidimoko Marguerite; Lee, Jung-Bum; Hayashi, Toshimitsu

    2005-07-01

    The effects of methyl jasmonate (MeJA) on isoprenoid production were evaluated in cultured tissues of Scoparia dulcis. It was found that MeJA suppressed the accumulation of chlorophylls, carotenoids, phytol and beta-sitosterol in the tissues. MeJA, however, remarkably enhanced the production of scopadulcic acid B (SDB), with 10 microM being optimal observed concentration for stimulation of SDB production. The maximum concentration of SDB was observed 6 d after MeJA treatment.

  5. Metabolomics analysis and biosynthesis of rosmarinic acid in Agastache rugosa Kuntze treated with methyl jasmonate.

    Yeon Bok Kim

    Full Text Available This study investigated the effect of methyl jasmonate (MeJA on metabolic profiles and rosmarinic acid (RA biosynthesis in cell cultures of Agastache rugosa Kuntze. Transcript levels of phenylpropanoid biosynthetic genes, i.e., ArPAL, Ar4CL, and ArC4H, maximally increased 4.5-fold, 3.4-fold, and 3.5-fold, respectively, compared with the untreated controls, and the culture contained relatively high amounts of RA after exposure of cells to 50 µM MeJA. RA levels were 2.1-, 4.7-, and 3.9-fold higher after exposure to 10, 50, and 100 µM MeJA, respectively, than those in untreated controls. In addition, the transcript levels of genes attained maximum levels at different time points after the initial exposure. The transcript levels of ArC4H and Ar4CL were transiently induced by MeJA, and reached a maximum of up to 8-fold at 3 hr and 6 hr, respectively. The relationships between primary metabolites and phenolic acids in cell cultures of A. rugosa treated with MeJA were analyzed by gas chromatography coupled with time-of-flight mass spectrometry. In total, 45 metabolites, including 41 primary metabolites and 4 phenolic acids, were identified from A. rugosa. Metabolite profiles were subjected to partial least square-discriminate analysis to evaluate the effects of MeJA. The results indicate that both phenolic acids and precursors for the phenylpropanoid biosynthetic pathway, such as aromatic amino acids and shikimate, were induced as a response to MeJA treatment. Therefore, MeJA appears to have an important impact on RA accumulation, and the increased RA accumulation in the treated cells might be due to activation of the phenylpropanoid genes ArPAL, ArC4H, and Ar4CL.

  6. Short- and long-term changes in sugarbeet (Beta vulgaris L. gene expression due to postharvest jasmonic acid treatment - Data

    Lucilene Silva de Oliveira

    2017-04-01

    Full Text Available Jasmonic acid is a natural plant hormone that induces native defense responses in plants. Sugarbeet (Beta vulgaris L. root unigenes that were differentially expressed 2 and 60 days after a postharvest jasmonic acid treatment are presented. Data include changes in unigene expression relative to water-treated controls, unigene annotations against nonredundant (Nr, Swiss-Prot, Clusters of Orthologous Groups (COG, and Kyoto Encyclopedia of Genes and Genomes (KEGG protein databases, and unigene annotations with Gene Ontology (GO terms. Putative defense unigenes are compiled and annotated against the sugarbeet genome. Differential gene expression data were generated by RNA sequencing. Interpretation of the data is available in the research article, “Jasmonic acid causes short- and long-term alterations to the transcriptome and the expression of defense genes in sugarbeet roots” (K.K. Fugate, L.S. Oliveira, J.P. Ferrareze, M.D. Bolton, E.L. Deckard, F.L. Finger, 2017 [1]. Public dissemination of this dataset will allow further analyses of the data.

  7. The efficacy of Beauveria bassiana, jasmonic acid and chlorantraniliprole on larval populations of Helicoverpa armigera in chickpea crop ecosystems.

    Younas, Aneela; Wakil, Waqas; Khan, Zaeema; Shaaban, Muhammad; Prager, Sean Michael

    2017-02-01

    A robust integrated pest management (IPM) programme is needed to reduce the use of insecticides in controlling Helicoverpa armigera. Therefore, a 2 year field study was conducted to evaluate the use of alternative control measures (biochemical use) for H. armigera relative to exclusively using chemical insecticides. The entomopathogenic fungus Beauveria bassiana, jasmonic acid and the insecticide chlorantraniliprole were each applied twice during the chickpea growing season. All three applied materials (either alone or combined) significantly (P ≤ 0.05) reduced the larval population of H. armigera and pod infestation. Effects increased with time, and the maximum difference was observed 7 days after the second application in each year. The lowest numbers of larvae per plant and pod infestation were in the B. bassiana 3.21 × 10 6 + chlorantraniliprole treatment in both 2009/2010 and 2010/2011 year. The reduction in the larval population and pod infestation increased chickpea yield and the highest yield in both seasons, and the maximum yield was obtained in the B. bassiana 3.21 × 10 6 + chlorantraniliprole treatment. The populations of natural enemies were highest in the jasmonic acid treatment. The results suggest that B. bassiana, jasmonic acid and chlorantraniliprole may be useful components for the H. armigera IPM strategy. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  8. The pokeweed leaf mRNA transcriptome and its regulation by jasmonic acid.

    Kira C.M. Neller

    2016-03-01

    Full Text Available The American pokeweed plant, Phytolacca americana, is recognized for synthesizing pokeweed antiviral protein (PAP, a ribosome inactivating protein (RIP that inhibits the replication of several plant and animal viruses. The plant is also a heavy metal accumulator with applications in soil remediation. However, little is known about pokeweed stress responses, as large-scale sequencing projects have not been performed for this species. Here, we sequenced the mRNA transcriptome of pokeweed in the presence and absence of jasmonic acid (JA, a hormone mediating plant defense. Trinity-based de novo assembly of mRNA from leaf tissue and BLASTx homology searches against public sequence databases resulted in the annotation of 59 096 transcripts. Differential expression analysis identified JA-responsive genes that may be involved in defense against pathogen infection and herbivory. We confirmed the existence of several PAP isoforms and cloned a potentially novel isoform of PAP. Expression analysis indicated that PAP isoforms are differentially responsive to JA, perhaps indicating specialized roles within the plant. Finally, we identified 52 305 natural antisense transcript pairs, four of which comprised PAP isoforms, suggesting a novel form of RIP gene regulation. This transcriptome-wide study of a Phytolaccaceae family member provides a source of new genes that may be involved in stress tolerance in this plant. The sequences generated in our study have been deposited in the SRA database under project # SRP069141.

  9. Jasmonic acid protects etiolated seedlings of Arabidopsis thaliana against herbivorous arthropods.

    Boex-Fontvieille, Edouard; Rustgi, Sachin; Von Wettstein, Diter; Pollmann, Stephan; Reinbothe, Steffen; Reinbothe, Christiane

    2016-08-02

    Seed predators can cause mass ingestion of larger seed populations. As well, herbivorous arthropods attempt to attack etiolated seedlings and chose the apical hook for ingestion, aimed at dropping the cotyledons for later consumption. Etiolated seedlings, as we show here, have established an efficient mechanism of protecting their Achilles' heel against these predators, however. Evidence is provided for a role of jasmonic acid (JA) in this largely uncharacterized plant-herbivore interaction during skotomorphogenesis and that this comprises the temporally and spatially tightly controlled synthesis of a cysteine protease inhibitors of the Kunitz family. Interestingly, the same Kunitz protease inhibitor was found to be expressed in flowers of Arabidopsis where endogenous JA levels are high for fertility. Because both the apical hook and inflorescences were preferred isopod targets in JA-deficient plants that could be rescued by exogenously administered JA, our data identify a JA-dependent mechanism of plant arthropod deterrence that is recalled in different organs and at quite different times of plant development.

  10. The Arabidopsis mutant cev1 has constitutively active jasmonate and ethylene signal pathways and enhanced resistance to pathogens.

    Ellis, C; Turner, J G

    2001-05-01

    Jasmonates (JAs) inhibit plant growth and induce plant defense responses. To define genes in the Arabidopsis JA signal pathway, we screened for mutants with constitutive expression of a luciferase reporter for the JA-responsive promoter from the vegetative storage protein gene VSP1. One mutant, named constitutive expression of VSP1 (cev1), produced plants that were smaller than wild type, had stunted roots with long root hairs, accumulated anthocyanin, had constitutive expression of the defense-related genes VSP1, VSP2, Thi2.1, PDF1.2, and CHI-B, and had enhanced resistance to powdery mildew diseases. Genetic evidence indicated that the cev1 phenotype required both COI1, an essential component of the JA signal pathway, and ETR1, which encodes the ethylene receptor. We conclude that cev1 stimulates both the JA and the ethylene signal pathways and that CEV1 regulates an early step in an Arabidopsis defense pathway.

  11. Both the Jasmonic Acid and the Salicylic Acid Pathways Contribute to Resistance to the Biotrophic Clubroot Agent Plasmodiophora brassicae in Arabidopsis.

    Lemarié, Séverine; Robert-Seilaniantz, Alexandre; Lariagon, Christine; Lemoine, Jocelyne; Marnet, Nathalie; Jubault, Mélanie; Manzanares-Dauleux, Maria J; Gravot, Antoine

    2015-11-01

    The role of salicylic acid (SA) and jasmonic acid (JA) signaling in resistance to root pathogens has been poorly documented. We assessed the contribution of SA and JA to basal and partial resistance of Arabidopsis to the biotrophic clubroot agent Plasmodiophora brassicae. SA and JA levels as well as the expression of the SA-responsive genes PR2 and PR5 and the JA-responsive genes ARGAH2 and THI2.1 were monitored in infected roots of the accessions Col-0 (susceptible) and Bur-0 (partially resistant). SA signaling was activated in Bur-0 but not in Col-0. The JA pathway was weakly activated in Bur-0 but was strongly induced in Col-0. The contribution of both pathways to clubroot resistance was then assessed using exogenous phytohormone application and mutants affected in SA or JA signaling. Exogenous SA treatment decreased clubroot symptoms in the two Arabidopsis accessions, whereas JA treatment reduced clubroot symptoms only in Col-0. The cpr5-2 mutant, in which SA responses are constitutively induced, was more resistant to clubroot than the corresponding wild type, and the JA signaling-deficient mutant jar1 was more susceptible. Finally, we showed that the JA-mediated induction of NATA1 drove N(δ)-acetylornithine biosynthesis in infected Col-0 roots. The 35S::NATA1 and nata1 lines displayed reduced or enhanced clubroot symptoms, respectively, thus suggesting that in Col-0 this pathway was involved in the JA-mediated basal clubroot resistance. Overall, our data support the idea that, depending on the Arabidopsis accession, both SA and JA signaling can play a role in partial inhibition of clubroot development in compatible interactions with P. brassicae. © The Author 2015. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  12. ORA59 and EIN3 interaction couples jasmonate-ethylene synergistic action to antagonistic salicylic acid regulation of PDF expression.

    He, Xiang; Jiang, Jishan; Wang, Chang-Quan; Dehesh, Katayoon

    2017-04-01

    Hormonal crosstalk is central for tailoring plant responses to the nature of challenges encountered. The role of antagonism between the two major defense hormones, salicylic acid (SA) and jasmonic acid (JA), and modulation of this interplay by ethylene (ET) in favor of JA signaling pathway in plant stress responses is well recognized, but the underlying mechanism is not fully understood. Here, we show the opposing function of two transcription factors, ethylene insensitive3 (EIN3) and EIN3-Like1 (EIL1), in SA-mediated suppression and JA-mediated activation of PLANT DEFENSIN1.2 (PDF1.2). This functional duality is mediated via their effect on protein, not transcript levels of the PDF1.2 transcriptional activator octadecanoid-responsive Arabidopsis59 (ORA59). Specifically, JA induces ORA59 protein levels independently of EIN3/EIL1, whereas SA reduces the protein levels dependently of EIN3/EIL1. Co-infiltration assays revealed nuclear co-localization of ORA59 and EIN3, and split-luciferase together with yeast-two-hybrid assays established their physical interaction. The functional ramification of the physical interaction is EIN3-dependent degradation of ORA59 by the 26S proteasome. These findings allude to SA-responsive reduction of ORA59 levels mediated by EIN3 binding to and targeting of ORA59 for degradation, thus nominating ORA59 pool as a coordination node for the antagonistic function of ET/JA and SA. © 2017 Institute of Botany, Chinese Academy of Sciences.

  13. The Roles of Alpha-Momorcharin and Jasmonic Acid in Modulating the Response of Momordica charantia to Cucumber Mosaic Virus.

    Yang, Ting; Meng, Yao; Chen, Li-Juan; Lin, Hong-Hui; Xi, De-Hui

    2016-01-01

    Alpha-momorcharin (α-MMC) is a type-I ribosome inactivating protein with a molecular weight of 29 kDa that is found in Momordica charantia , and has been shown to be effective against a broad range of human viruses as well as having anti-tumor activities. However, the role of endogenous α-MMC under viral infection and the mechanism of the anti-viral activities of α-MMC in plants are still unknown. To study the effect of α-MMC on plant viral defense and how α-MMC increases plant resistance to virus, the M. charantia - cucumber mosaic virus (CMV) interaction system was investigated. The results showed that the α-MMC level was positively correlated with the resistance of M. charantia to CMV. α-MMC treatment could alleviate photosystem damage and enhance the ratio of glutathione/glutathione disulfide in M. charantia under CMV infection. The relationship of α-MMC and defense related phytohormones, and their roles in plant defense were further investigated. α-MMC treatment led to a significant increase of jasmonic acid (JA) and vice versa, while there was no obvious relevance between salicylic acid and α-MMC. In addition, reactive oxygen species (ROS) were induced in α-MMC-pretreated plants, in a similar way to the ROS burst in JA-pretreated plants. The production of ROS in both ibuprofen (JA inhibitor) and (α-MMC+ibuprofen)-pretreated plants was reduced markedly, leading to a greater susceptibility of M. charantia to CMV. Our results indicate that the anti-viral activities of α-MMC in M. charantia may be accomplished through the JA related signaling pathway.

  14. Wounding stimulates ALLENE OXIDE SYNTHASE gene and increases the level of jasmonic acid in Ipomoea nil cotyledons

    Emilia Wilmowicz

    2016-03-01

    Full Text Available Allene oxide synthase (AOS encodes the first enzyme in the lipoxygenase pathway, which is responsible for jasmonic acid (JA formation. In this study we report the molecular cloning and characterization of InAOS from Ipomoea nil. The full-length gene is composed of 1662 bp and encodes for 519 amino acids. The predicted InAOS contains PLN02648 motif, which is evolutionarily conserved and characteristic for functional enzymatic proteins. We have shown that wounding led to a strong stimulation of the examined gene activity in cotyledons and an increase in JA level, which suggest that this compound may be a modulator of stress responses in I. nil.

  15. Circadian Stress Regimes Affect the Circadian Clock and Cause Jasmonic Acid-Dependent Cell Death in Cytokinin-Deficient Arabidopsis Plants[OPEN

    Nitschke, Silvia; Cortleven, Anne; Iven, Tim; Havaux, Michel; Schmülling, Thomas

    2016-01-01

    The circadian clock helps plants measure daylength and adapt to changes in the day-night rhythm. We found that changes in the light-dark regime triggered stress responses, eventually leading to cell death, in leaves of Arabidopsis thaliana plants with reduced cytokinin levels or defective cytokinin signaling. Prolonged light treatment followed by a dark period induced stress and cell death marker genes while reducing photosynthetic efficiency. This response, called circadian stress, is also characterized by altered expression of clock and clock output genes. In particular, this treatment strongly reduced the expression of CIRCADIAN CLOCK ASSOCIATED1 (CCA1) and LATE ELONGATED HYPOCOTYL (LHY). Intriguingly, similar changes in gene expression and cell death were observed in clock mutants lacking proper CCA1 and LHY function. Circadian stress caused strong changes in reactive oxygen species- and jasmonic acid (JA)-related gene expression. The activation of the JA pathway, involving the accumulation of JA metabolites, was crucial for the induction of cell death, since the cell death phenotype was strongly reduced in the jasmonate resistant1 mutant background. We propose that adaptation to circadian stress regimes requires a normal cytokinin status which, acting primarily through the AHK3 receptor, supports circadian clock function to guard against the detrimental effects of circadian stress. PMID:27354555

  16. Overexpression of NtWRKY50 Increases Resistance to Ralstonia solanacearum and Alters Salicylic Acid and Jasmonic Acid Production in Tobacco.

    Liu, Qiuping; Liu, Ying; Tang, Yuanman; Chen, Juanni; Ding, Wei

    2017-01-01

    WRKY transcription factors (TFs) modulate plant responses to biotic and abiotic stresses. Here, we characterized a WRKY IIc TF, NtWRKY50, isolated from tobacco ( Nicotiana tabacum ) plants. The results showed that NtWRKY50 is a nuclear-localized protein and that its gene transcript is induced in tobacco when inoculated with the pathogenic bacterium Ralstonia solanacearum . Overexpression of NtWRKY50 enhanced bacterial resistance, which correlated with enhanced SA and JA/ET signaling genes. However, silencing of the NtWRKY50 gene had no obvious effects on plant disease resistance, implying functional redundancy of NtWRKY50 with other TFs. In addition, it was found that NtWRKY50 can be induced by various biotic or abiotic stresses, such as Potato virus Y, Rhizoctonia solani, Phytophthora parasitica , hydrogen peroxide, heat, cold, and wounding as well as the hormones salicylic acid (SA), jasmonic acid (JA), and ethylene (ET). Importantly, additional analysis suggests that NtWRKY50 overexpression markedly promotes SA levels but prevents pathogen-induced JA production. These data indicate that NtWRKY50 overexpression leads to altered SA and JA content, increased expression of defense-related genes and enhanced plant resistance to R. solanacearum. These probably due to increased activity of endogenous NtWRKY50 gene or could be gain-of-function phenotypes by altering the profile of genes affected by NtWRKY50 .

  17. Perception of low red:far-red ratio compromises both salicylic acid- and jasmonic acid-dependent pathogen defences in Arabidopsis.

    de Wit, Mieke; Spoel, Steven H; Sanchez-Perez, Gabino F; Gommers, Charlotte M M; Pieterse, Corné M J; Voesenek, Laurentius A C J; Pierik, Ronald

    2013-07-01

    In dense stands of plants, such as agricultural monocultures, plants are exposed simultaneously to competition for light and other stresses such as pathogen infection. Here, we show that both salicylic acid (SA)-dependent and jasmonic acid (JA)-dependent disease resistance is inhibited by a simultaneously reduced red:far-red light ratio (R:FR), the early warning signal for plant competition. Conversely, SA- and JA-dependent induced defences did not affect shade-avoidance responses to low R:FR. Reduced pathogen resistance by low R:FR was accompanied by a strong reduction in the regulation of JA- and SA-responsive genes. The severe inhibition of SA-responsive transcription in low R:FR appeared to be brought about by the repression of SA-inducible kinases. Phosphorylation of the SA-responsive transcription co-activator NPR1, which is required for full induction of SA-responsive transcription, was indeed reduced and may thus play a role in the suppression of SA-mediated defences by low R:FR-mediated phytochrome inactivation. Our results indicate that foraging for light through the shade-avoidance response is prioritised over plant immune responses when plants are simultaneously challenged with competition and pathogen attack. © 2013 The Authors The Plant Journal © 2013 John Wiley & Sons Ltd.

  18. Salicylic acid and methyl jasmonate enhance drought tolerance in chamomile plants

    Nazarli Hossein

    2014-04-01

    Full Text Available Introduction: The dried flowers of chamomile contain many terpenoids and flavonoids contributing to its medicinal properties. Salicylic acid (SA and methyl jasmonate (MeJA have antioxidant properties and function as direct radical scavengers. Two Matricaria chamomilla cultivars (Bodgold and Hungary breed seeds were used in this study to investigate the effects of exogenous application of SA and MeJA on protection against drought stress as well as on changes of malone dialdehyde (MDA and electrolyte leakage index (ELI, and the fluctuation of proline and soluble sugars content in the leaves under drought stress. Methods: The experiment was conducted in a factorial design based on randomized complete blocks with three replicates. Chamomile plants were treated by two levels of drought stress as well as two different levels of MeJA (i.e., 0.0 and 100 μM and SA (i.e., 0.0 and 0.5 mM solutions. Results: There was a dramatic drought induced increase in the MDA content (128% and ELI (49% in the leaves. Deleterious effect of drought stress was more severe in untreated plants than in treated ones. Treatments with SA and MeJA significantly improved drought tolerance in chamomile plants. These treatments effectively maintained membrane integrity, thereby retarding electrolyte leakage and membrane lipid peroxidation (MDA. Treatments with SA and MeJA were also effective in enhancing the antioxidant concentrations of proline and soluble sugars. Conclusion: The production of these antioxidants could have been part of a defence system against drought damage, reducing MDA and ELI and maintaining membrane stability.

  19. Biochar amendment changes jasmonic acid levels in two rice varieties and alters their resistance to herbivory.

    Waqas, Muhammad; Shahzad, Raheem; Hamayun, Muhammad; Asaf, Sajjad; Khan, Abdul Latif; Kang, Sang-Mo; Yun, Sopheap; Kim, Kyung-Min; Lee, In-Jung

    2018-01-01

    Biochar addition to soil not only sequesters carbon for the long-term but enhances agricultural productivity. Several well-known benefits arise from biochar amendment, including constant provision of nutrients, increased soil moisture retention, decreased soil bulk density, and sometimes the induction of systemic resistance against foliar and soil borne plant pathogens. However, no research has investigated the potential of biochar to increase resistance against herbivory. The white-backed plant hopper (WBPH) (Sogatella furcifera Horváth) is a serious agricultural pest that targets rice (Oryza sativa L.), a staple crop that feeds half of the world's human population. Therefore, we investigated the (1) optimization of biochar amendment levels for two rice varieties ('Cheongcheong' and 'Nagdong') and (2) subsequent effects of different biochar amendments on resistance and susceptibility of these two varieties to WBPH infestation. Initial screening results for the optimization level revealed that the application of biochar 10% (w/w) to the rooting media significantly improved plant physiological characteristics of both rice varieties. However, levels of biochar amendment, mainly 1, 2, 3, and 20%, resulted in negative effects on plant growth characteristics. Cheongcheong and Nagdong rice plants grown with the optimum biochar level showed contrasting reactions to WBPH infestation. Specifically, biochar application significantly increased plant growth characteristics of Nagdong when exposed to WBPH infestation and significantly decreased these characteristics in Cheongcheong. The amount of WBPH-induced damage to plants was significantly lower and higher in Nagdong and Cheongcheong, respectively, compared to that in the controls. Higher levels of jasmonic acid caused by the biochar priming effect could have accumulated in response to WBPH infestation, resulting in a maladaptive response to stress, negatively affecting growth and resistance to WBPH in Cheongcheong. This

  20. A broad-spectrum, efficient and nontransgenic approach to control plant viruses by application of salicylic acid and jasmonic acid.

    Shang, Jing; Xi, De-Hui; Xu, Fei; Wang, Shao-Dong; Cao, Sen; Xu, Mo-Yun; Zhao, Ping-Ping; Wang, Jian-Hui; Jia, Shu-Dan; Zhang, Zhong-Wei; Yuan, Shu; Lin, Hong-Hui

    2011-02-01

    Plant viruses cause many diseases that lead to significant economic losses. However, most of the approaches to control plant viruses, including transgenic processes or drugs are plant-species-limited or virus-species-limited, and not very effective. We introduce an application of jasmonic acid (JA) and salicylic acid (SA), a broad-spectrum, efficient and nontransgenic method, to improve plant resistance to RNA viruses. Applying 0.06 mM JA and then 0.1 mM SA 24 h later, enhanced resistance to Cucumber mosaic virus (CMV), Tobacco mosaic virus (TMV) and Turnip crinkle virus (TCV) in Arabidopsis, tobacco, tomato and hot pepper. The inhibition efficiency to virus replication usually achieved up to 80-90%. The putative molecular mechanism was investigated. Some possible factors affecting the synergism of JA and SA have been defined, including WRKY53, WRKY70, PDF1.2, MPK4, MPK2, MPK3, MPK5, MPK12, MPK14, MKK1, MKK2, and MKK6. All genes involving in the synergism of JA and SA were investigated. This approach is safe to human beings and environmentally friendly and shows potential as a strong tool for crop protection against plant viruses.

  1. Impact of salicylic acid- and jasmonic acid-regulated defences on root colonization by Trichoderma harzianum T-78.

    Martínez-Medina, Ainhoa; Appels, Freek V W; van Wees, Saskia C M

    2017-08-03

    We recently found that the beneficial fungus Trichoderma harzianum T-78 primes tomato plants for salicylic acid (SA)- and jasmonic acid (JA)-regulated defenses, resulting in enhanced resistance against the root knot nematode Meloidogyne incognita. By using SA- and JA-impaired mutant lines and exogenous hormonal application, here we investigated whether the SA- and JA-pathways also have a role in T-78 root colonization of Arabidopsis thaliana. Endophytic colonization by T-78 was faster in the SA-impaired mutant sid2 than in the wild type. Moreover, elicitation of SA-dependent defenses by SA application reduced T-78 colonization, indicating that the SA-pathway affects T-78 endophytism. In contrast, elicitation of the JA-pathway, which antagonized SA-dependent defenses, resulted in enhanced endophytic colonization by T-78. These findings are in line with our previous observation that SA-dependent defenses are repressed by T-78, which likely aids colonization by the endophytic fungus.

  2. Induced resistance to Helicoverpa armigera through exogenous application of jasmonic acid and salicylic acid in groundnut, Arachis hypogaea.

    War, Abdul Rashid; Paulraj, Michael Gabriel; Ignacimuthu, Savarimuthu; Sharma, Hari Chand

    2015-01-01

    Induced resistance to Helicoverpa armigera through exogenous application of jasmonic acid (JA) and salicylic acid (SA) was studied in groundnut genotypes (ICGV 86699, ICGV 86031, ICG 2271 and ICG 1697) with different levels of resistance to insects and the susceptible check JL 24 under greenhouse conditions. Activities of oxidative enzymes and the amounts of secondary metabolites and proteins were quantified at 6 days after JA and SA application/insect infestation. Data were also recorded on plant damage and H. armigera larval weights and survival. Higher levels of enzymatic activities and amounts of secondary metabolites were observed in the insect-resistant genotypes pretreated with JA and then infested with H. armigera than in JL 24. The insect-resistant genotypes suffered lower insect damage and resulted in poor survival and lower weights of H. armigera larvae than JL 24. In some cases, JA and SA showed similar effects. JA and SA induced the activity of antioxidative enzymes in groundnut plants against H. armigera, and reduced its growth and development. However, induced response to application of JA was greater than to SA, and resulted in reduced plant damage, and larval weights and survival, suggesting that induced resistance can be used as a component of pest management in groundnut. © 2014 Society of Chemical Industry.

  3. ORA EST : functional analysis of jasmonate-responsive AP2/ERF-domain transcription factors in Arabidopsis thaliana

    Pré, Martial

    2006-01-01

    Plants defend themselves against stress, including pathogen or herbivore attack, via biosynthesis of defense proteins and of protective compounds called secondary metabolites. Stress induces these responses via a complex signal transduction network with jasmonic acid (JA) and related compounds as

  4. Effect of "6"0Co-induced gamma radiation exposure and Jasmonic acid on antioxidant responses in Cowpea varieties

    Shukla, Pradeep Kumar; Bhagoji, Ravi; Ramteke, P.W.; Misra, Pragati; Maurice, Navodita

    2017-01-01

    Cowpea used to be the first crop harvested before the cereal crops are ready and therefore is referred to as 'hungry-season crop'. The gamma irradiation is known to increase nutritional values of food sources and also enhance and accelerate growth of certain vegetables Antioxidants are the metabolites, produced by the plant in response to different stress conditions e.g. radiation stress etc. Seeds of four cowpea varieties were treated with different doses of gamma radiation and effect of jasmonic acid (JA) on antioxidant response of cowpea was studied. The results showed that there was no linear correlation between application of JA and different antioxidant contents. (author)

  5. Jasmonic and salicylic acids enhanced phytochemical production and biological activities in cell suspension cultures of spine gourd (Momordica dioica Roxb).

    Chung, Ill-Min; Rekha, Kaliyaperumal; Rajakumar, Govindasamy; Thiruvengadam, Muthu

    2017-03-01

    In vitro cell suspension culture was established for the production of commercially valuable phytochemicals in Momordica dioica. The influence of elicitors in jasmonic acid (JA) and salicylic acid (SA) increased their effect on phytochemical production and biomass accumulation in M. dioica. The results indicate that compared with non-elicited cultures, JA- and SA-elicited cell suspension cultures had significantly enhanced phenolic, flavonoid, and carotenoid production, as well as antioxidant, antimicrobial, and antiproliferative activities. Furthermore, elicited cultures produced 22 phenolic compounds, such as flavonols, hydroxycinnamic acids, and hydroxybenzoic acids. Greater biomass production, phytochemical accumulation, and biological activity occurred in JA- than in SA-elicited cell cultures. This study is the first to successfully establish M. dioica cell suspension cultures for the production of phenolic compounds and carotenoids, as well as for biomass accumulation.

  6. fektivitas Penambahan Elisitor Asam Jasmonik dalam Peningkatan Sintesis Senyawa Bioaktif Andrografolid pada Kultur Suspensi Sel Sambiloto (Effectiveness of Jasmonic Acid Elicitor Addition for Andrographolide Synthesis Induction of Sambiloto Culture

    Noor Aini Habibah

    2009-03-01

    Full Text Available In this research, we have studied synthesis of improvement of andrographolid bioactive compound on cell culture of sambiloto by addition of jasmonic acid. The essential problems in this research are firstly, the effects of addition of jasmonic acid either can induce or not andrographolide synthesis improvement of cell culture of sambiloto and secondly, to observe the largest content of andrographolide in jasmonic acid concentrations. Meanwhile, the purpose of this research are to observe the functions of jasmonic acid elicitor for induction of andrographolide synthesis improvement of cell culture of sambiloto and to optimize jasmonic acid concentrations which can produce the largest andrographolide content. The independent variable is concentration of addition of jasmonic acid on cell culture and the dependent variable are the growth of cell suspension culture and andrographolide bioactive content. Experiment result show that the optimum medium of sambiloto cell consist of Murashige & Skoog (1962 medium supplemented by 0,5 ppm kinetin and 2,4-D 5 ppm. The cell growth phases are the followings : lag phase at age of 0-5 days, exponential phase of 5-15 days, and stationary phase at age of longer than 15 days. The highest andrographolide was 4,66 x 10-2 reached in cell culture was supplemented with 10 µM jasmonic acid. Keywords : andrographolide, sambiloto cell suspension culture, jasmonic acid elicitor.

  7. Salicylic Acid and Jasmonic Acid Pathways are Activated in Spatially Different Domains Around the Infection Site During Effector-Triggered Immunity in Arabidopsis thaliana.

    Betsuyaku, Shigeyuki; Katou, Shinpei; Takebayashi, Yumiko; Sakakibara, Hitoshi; Nomura, Nobuhiko; Fukuda, Hiroo

    2018-01-01

    The innate immune response is, in the first place, elicited at the site of infection. Thus, the host response can be different among the infected cells and the cells surrounding them. Effector-triggered immunity (ETI), a form of innate immunity in plants, is triggered by specific recognition between pathogen effectors and their corresponding plant cytosolic immune receptors, resulting in rapid localized cell death known as hypersensitive response (HR). HR cell death is usually limited to a few cells at the infection site, and is surrounded by a few layers of cells massively expressing defense genes such as Pathogenesis-Related Gene 1 (PR1). This virtually concentric pattern of the cellular responses in ETI is proposed to be regulated by a concentration gradient of salicylic acid (SA), a phytohormone accumulated around the infection site. Recent studies demonstrated that jasmonic acid (JA), another phytohormone known to be mutually antagonistic to SA in many cases, is also accumulated in and required for ETI, suggesting that ETI is a unique case. However, the molecular basis for this uniqueness remained largely to be solved. Here, we found that, using intravital time-lapse imaging, the JA signaling pathway is activated in the cells surrounding the central SA-active cells around the infection sites in Arabidopsis thaliana. This distinct spatial organization explains how these two phythormone pathways in a mutually antagonistic relationship can be activated simultaneously during ETI. Our results re-emphasize that the spatial consideration is a key strategy to gain mechanistic insights into the apparently complex signaling cross-talk in immunity. © The Author 2017. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists.

  8. Constitutive activation of jasmonate signaling in an Arabidopsis mutant correlates with enhanced resistance to Erysiphe cichoracearum, Pseudomonas syringae, and Myzus persicae.

    Ellis, Christine; Karafyllidis, Ioannis; Turner, John G

    2002-10-01

    In Arabidopsis spp., the jasmonate (JA) response pathway generally is required for defenses against necrotrophic pathogens and chewing insects, while the salicylic acid (SA) response pathway is generally required for specific, resistance (R) gene-mediated defenses against both biotrophic and necrotrophic pathogens. For example, SA-dependent defenses are required for resistance to the biotrophic fungal pathogen Erysiphe cichoracearum UCSC1 and the bacterial pathogen Pseudomonas syringae pv. maculicola, and also are expressed during response to the green peach aphid Myzus persicae. However, recent evidence indicates that the expression of JA-dependent defenses also may confer resistance to E. cichoracearum. To confirm and to extend this observation, we have compared the disease and pest resistance of wild-type Arabidopsis plants with that of the mutants coil, which is insensitive to JA, and cev1, which has constitutive JA signaling. Measurements of the colonization of these plants by E. cichoracearum, P. syringae pv. maculicola, and M. persicae indicated that activation of the JA signal pathway enhanced resistance, and was associated with the activation of JA-dependent defense genes and the suppression of SA-dependent defense genes. We conclude that JA and SA induce alternative defense pathways that can confer resistance to the same pathogens and pests.

  9. Simultaneous induction of jasmonic acid and disease-responsive genes signifies tolerance of American elm to Dutch elm disease

    Sherif , S. M.; Shukla, M. R.; Murch, S. J.; Bernier, L.; Saxena, P. K.

    2016-01-01

    Dutch elm disease (DED), caused by three fungal species in the genus Ophiostoma, is the most devastating disease of both native European and North American elm trees. Although many tolerant cultivars have been identified and released, the tolerance mechanisms are not well understood and true resistance has not yet been achieved. Here we show that the expression of disease-responsive genes in reactions leading to tolerance or susceptibility is significantly differentiated within the first 144 hours post-inoculation (hpi). Analysis of the levels of endogenous plant defense molecules such as jasmonic acid (JA) and salicylic acid (SA) in tolerant and susceptible American elm saplings suggested SA and methyl-jasmonate as potential defense response elicitors, which was further confirmed by field observations. However, the tolerant phenotype can be best characterized by a concurrent induction of JA and disease-responsive genes at 96 hpi. Molecular investigations indicated that the expression of fungal genes (i.e. cerato ulmin) was also modulated by endogenous SA and JA and this response was unique among aggressive and non-aggressive fungal strains. The present study not only provides better understanding of tolerance mechanisms to DED, but also represents a first, verified template for examining simultaneous transcriptomic changes during American elm-fungus interactions. PMID:26902398

  10. A liquid chromatography/electrospray ionisation tandem mass spectrometry method for the simultaneous quantification of salicylic, jasmonic and abscisic acids in Coffea arabica leaves.

    de Sá, Marta; Ferreira, João P; Queiroz, Vagner T; Vilas-Boas, Luís; Silva, Maria C; Almeida, Maria H; Guerra-Guimarães, Leonor; Bronze, Maria R

    2014-02-01

    Plants have developed an efficient system of recognition that induces a complex network of signalling molecules such as salicylic acid (SA), jasmonic acid (JA) and abscisic acid (ABA) in case of a pathogenic infection. The use of specific and sensitive methods is mandatory for the analysis of compounds in these complex samples. In this study a liquid chromatography/electrospray ionisation tandem mass spectrometry method was developed and validated for the simultaneous quantification of SA, JA and ABA in Coffea arabica (L.) leaves in order to understand the role of these phytohormones in the signalling network involved in the coffee defence response against Hemileia vastatrix. The results showed that the method was specific, linear (r ≥ 0.99) in the range 0.125-1.00 µg mL⁻¹ for JA and ABA and 0.125-5.00 µg mL⁻¹ for SA, and precise (relative standard deviation ≤11%), and the limit of detection (0.010 µg g⁻¹ fresh weight) was adequate for quantifying these phytohormones in this type of matrix. In comparison with healthy leaves, those infected with H. vastatrix (resistance reaction) displayed an increase in SA level 24 h after inoculation, suggesting the involvement of an SA-dependent pathway in coffee resistance. © 2013 Society of Chemical Industry.

  11. Induced disease resistance signaling in plants

    Verhagen, B.W.M.; Loon, L.C. van; Pieterse, C.M.J.

    2006-01-01

    To protect themselves from disease, plants have evolved sophisticated inducible defense mechanisms in which the signal molecules salicylic acid, jasmonic acid and ethylene often play crucial roles. Elucidation of signaling pathways controlling induced disease resistance is a major objective in

  12. Endogenous jasmonic and salicylic acids levels in the Cd-hyperaccumulator Noccaea (Thlaspi) praecox exposed to fungal infection and/or mechanical stress.

    Llugany, M; Martin, S R; Barceló, J; Poschenrieder, C

    2013-08-01

    Sensitivity to Erysiphe in Noccaea praecox with low metal supply is related to the failure in enhancing SA. Cadmium protects against fungal-infection by direct toxicity and/or enhanced fungal-induced JA signaling. Metal-based defense against biotic stress is an attractive hypothesis on evolutionary advantages of plant metal hyperaccumulation. Metals may compensate for a defect in biotic stress signaling in hyperaccumulators (metal-therapy) by either or both direct toxicity to pathogens and by metal-induced alternative signaling pathways. Jasmonic acid (JA) and salicylic acid (SA) are well-established components of stress signaling pathways. However, few studies evaluate the influence of metals on endogenous concentrations of these defense-related hormones. Even less data are available for metal hyperaccumulators. To further test the metal-therapy hypothesis we analyzed endogenous SA and JA concentrations in Noccaea praecox, a cadmium (Cd) hyperaccumulator. Plants treated or not with Cd, were exposed to mechanical wounding, expected to enhance JA signaling, and/or to infection by biotrophic fungus Erysiphe cruciferarum for triggering SA. JA and SA were analyzed in leaf extracts using LC-ESI(-)-MS/MS. Plants without Cd were more susceptible to fungal attack than plants receiving Cd. Cadmium alone tended to increase leaf SA but not JA. Either or both fungal attack and mechanical wounding decreased SA levels and enhanced JA in the Cd-rich leaves of plants exposed to Cd. High leaf Cd in N. praecox seems to hamper biotic-stress-induced SA, while triggering JA signaling in response to fungal attack and wounding. To the best of our knowledge, this is the first report on the endogenous JA and SA levels in a Cd-hyperaccumulator exposed to different biotic and abiotic stresses. Our results support the view of a defect in SA stress signaling in Cd hyperaccumulating N. praecox.

  13. The Arabidopsis KH-Domain RNA-Binding Protein ESR1 Functions in Components of Jasmonate Signalling, Unlinking Growth Restraint and Resistance to Stress.

    Louise F Thatcher

    Full Text Available Glutathione S-transferases (GSTs play important roles in the protection of cells against toxins and oxidative damage where one Arabidopsis member, GSTF8, has become a commonly used marker gene for early stress and defense responses. A GSTF8 promoter fragment fused to the luciferase reporter gene was used in a forward genetic screen for Arabidopsis mutants with up-regulated GSTF8 promoter activity. This identified the esr1-1 (enhanced stress response 1 mutant which also conferred increased resistance to the fungal pathogen Fusarium oxysporum. Through positional cloning, the ESR1 gene was found to encode a KH-domain containing RNA-binding protein (At5g53060. Whole transcriptome sequencing of esr1-1 identified altered expression of genes involved in responses to biotic and abiotic stimuli, hormone signaling pathways and developmental processes. In particular was an overall significant enrichment for jasmonic acid (JA mediated processes in the esr1-1 down-regulated dataset. A subset of these genes were tested for MeJA inducibility and we found the expression of some but not all were reduced in esr1-1. The esr1-1 mutant was not impaired in other aspects of JA-signalling such as JA- sensitivity or development, suggesting ESR1 functions in specific components of the JA-signaling pathway. Examination of salicylic acid (SA regulated marker genes in esr1-1 showed no increase in basal or SA induced expression suggesting repression of JA-regulated genes is not due to antagonistic SA-JA crosstalk. These results define new roles for KH-domain containing proteins with ESR1 unlinking JA-mediated growth and defense responses.

  14. Jasmonic Acid, Abscisic Acid, and Salicylic Acid Are Involved in the Phytoalexin Responses of Rice to Fusarium fujikuroi, a High Gibberellin Producer Pathogen.

    Siciliano, Ilenia; Amaral Carneiro, Greice; Spadaro, Davide; Garibaldi, Angelo; Gullino, Maria Lodovica

    2015-09-23

    Fusarium fujikuroi, the causal agent of bakanae disease, is the main seedborne pathogen on rice. To understand the basis of rice resistance, a quantitative method to simultaneously detect phytohormones and phytoalexins was developed by using HPLC-MS/MS. With this method dynamic profiles and possible interactions of defense-related phytohormones and phytoalexins were investigated on two rice cultivars, inoculated or not with F. fujikuroi. In the resistant cultivar Selenio, the presence of pathogen induced high production of phytoalexins, mainly sakuranetin, and symptoms of bakanae were not observed. On the contrary, in the susceptible genotype Dorella, the pathogen induced the production of gibberellin and abscisic acid and inhibited jasmonic acid production, phytoalexins were very low, and bakanae symptoms were observed. The results suggested that a wide range of secondary metabolites are involved in plant defense against pathogens and phytoalexin synthesis could be an important factor for rice resistance against bakanae disease.

  15. Jasmonic acid-mediated defense suppresses brassinosteroid-mediated susceptibility to Rice black streaked dwarf virus infection in rice.

    He, Yuqing; Zhang, Hehong; Sun, Zongtao; Li, Junmin; Hong, Gaojie; Zhu, Qisong; Zhou, Xuebiao; MacFarlane, Stuart; Yan, Fei; Chen, Jianping

    2017-04-01

    Plant hormones play a vital role in plant immune responses. However, in contrast to the relative wealth of information on hormone-mediated immunity in dicot plants, little information is available on monocot-virus defense systems. We used a high-throughput-sequencing approach to compare the global gene expression of Rice black-streaked dwarf virus (RBSDV)-infected rice plants with that of healthy plants. Exogenous hormone applications and transgenic rice were used to test RBSDV infectivity and pathogenicity. Our results revealed that the jasmonic acid (JA) pathway was induced while the brassinosteroid (BR) pathway was suppressed in infected plants. Foliar application of methyl jasmonate (MeJA) or brassinazole (BRZ) resulted in a significant reduction in RBSDV incidence, while epibrassinolide (BL) treatment increased RBSDV infection. Infection studies using coi1-13 and Go mutants demonstrated JA-mediated resistance and BR-mediated susceptibility to RBSDV infection. A mixture of MeJA and BL treatment resulted in a significant reduction in RBSDV infection compared with a single BL treatment. MeJA application efficiently suppressed the expression of BR pathway genes, and this inhibition depended on the JA coreceptor OsCOI1. Collectively, our results reveal that JA-mediated defense can suppress the BR-mediated susceptibility to RBSDV infection. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

  16. Simultaneous determination of shikimic acid, salicylic acid and jasmonic acid in wild and transgenic Nicotiana langsdorffii plants exposed to abiotic stresses.

    Scalabrin, Elisa; Radaelli, Marta; Capodaglio, Gabriele

    2016-06-01

    The presence and relative concentration of phytohormones may be regarded as a good indicator of an organism's physiological state. The integration of the rolC gene from Agrobacterium rhizogenes and of the rat glucocorticoid receptor (gr) in Nicotiana langsdorffii Weinmann plants has shown to determine various physiological and metabolic effects. The analysis of wild and transgenic N. langsdorffii plants, exposed to different abiotic stresses (high temperature, water deficit, and high chromium concentrations) was conducted, in order to investigate the metabolic effects of the inserted genes in response to the applied stresses. The development of a new analytical procedure was necessary, in order to assure the simultaneous determination of analytes and to obtain an adequately low limit of quantification. For the first time, a sensitive HPLC-HRMS quantitative method for the simultaneous determination of salicylic acid, jasmonic acid and shikimic acid was developed and validated. The method was applied to 80 plant samples, permitting the evaluation of plant stress responses and highlighting some metabolic mechanisms. Salicylic, jasmonic and shikimic acids proved to be suitable for the comprehension of plant stress responses. Chemical and heat stresses showed to induce the highest changes in plant hormonal status, differently affecting plant response. The potential of each genetic modification toward the applied stresses was marked and particularly the resistance of the gr modified plants was evidenced. This work provides new information in the study of N. langsdorffii and transgenic organisms, which could be useful for the further application of these transgenes. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  17. EFFECTS OF SOME PLANT GROWTH REGULATORS ON JASMONIC ACID INDUCED INHIBITION OF SEED GERMINATION AND SEEDLING GROWTH OF BARLEY

    Kürşat ÇAVUŞOĞLU

    2009-02-01

    Full Text Available Abstract: The effects of gibberellic acid, kinetin, benzyladenine, ethylene, 24-epibrassinolide and polyamines (spermine, spermidine, putrescine, cadaverine on jasmonic acid inhibition of seed germination and seedling growth of barley were studied. All of the plant growth regulators studied were determined to have a succesful performance in reversing of the inhibitory effects of jasmonic acid on the seed germination and seedling growth. Moreover, the above mentioned growth regulators overcame the inhibitory effect of JA on the percentages of germination and coleoptile emergence in the same ratio, while GA3 was the most successful hormone on the fresh weight and radicle and coleoptile elongation in comparison with the other growth regulators. Key words: Barley, jasmonic acid, plant growth regulator, seed germination, seedling growth ARPANIN TOHUM ÇİMLENMESİ VE FİDE BÜYÜMESİNİN JASMONİK ASİT TEŞVİKLİ İNHİBİSYONU ÜZERİNE BAZI BİTKİ BÜYÜME DÜZENLEYİCİLERİNİN ETKİLERİ Özet: Arpanın tohum çimlenmesi ve fide büyümesinin jasmonik asit inhibisyonu üzerine gibberellik asit, kinetin, benziladenin, etilen, 24-epibrassinolit ve poliaminlerin (spermin, spermidin, putressin, kadaverin etkileri araştırılmıştır. Çalışılan bitki büyüme düzenleyicilerinin tümünün tohum çimlenmesi ve fide büyümesi üzerinde jasmonik asitin engelleyici etkisini tersine çevirmede başarılı bir performansa sahip oldukları belirlenmiştir. Dahası, yukarıda sözü edilen büyüme düzenleyicileri çimlenme ve koleoptil çıkış yüzdeleri üzerinde aynı oranda etkili olurken, taze ağırlık ve radikula ve koleoptil uzaması üzerinde diğer büyüme düzenleyicileri ile karşılaştırıldığında en başarılı hormon GA3 olmuştur. Anahtar kelimeler: Arpa, jasmonik asit, bitki büyüme düzenleyicisi, tohum çimlenmesi, fide büyümesi

  18. Effect of Exogenous Abscisic Acid and Methyl Jasmonate on Anthocyanin Composition, Fatty Acids, and Volatile Compounds of Cabernet Sauvignon (Vitis vinifera L.) Grape Berries.

    Ju, Yan-Lun; Liu, Min; Zhao, Hui; Meng, Jiang-Fei; Fang, Yu-Lin

    2016-10-12

    The anthocyanin composition, fatty acids, and volatile aromas are important for Cabernet Sauvignon grape quality. This study evaluated the effect of exogenous abscisic acid (ABA) and methyl jasmonate (MeJA) on the anthocyanin composition, fatty acids, lipoxygenase activity, and the volatile compounds of Cabernet Sauvignon grape berries. Exogenous ABA and MeJA improved the content of total anthocyanins (TAC) and individual anthocyanins. Lipoxygenase (LOX) activity also increased after treatment. Furthermore, 16 fatty acids were detected. The linoleic acid concentration gradually increased with ABA concentration. The fatty acid content decreased with increasing MeJA concentration and then increased again, with the exception of linoleic acid. After exogenous ABA and MeJA treatment, the C6 aroma content increased significantly. Interestingly, the exogenous ABA and MeJA treatments improved mainly the content of 1-hexanol, hexanal, and 2-heptanol. These results provide insight into the effect of plant hormones on wine grapes, which is useful for grape quality improvement.

  19. Synergism in the effect of prior jasmonic acid application on herbivore-induced volatile emission by Lima bean plants: transcription of a monoterpene synthase gene and volatile emission

    Menzel, T.R.; Weldegergis, B.T.; David, A.; Boland, W.; Gols, R.; Loon, van J.J.A.; Dicke, M.

    2014-01-01

    Jasmonic acid (JA) plays a central role in induced plant defence e.g. by regulating the biosynthesis of herbivore-induced plant volatiles that mediate the attraction of natural enemies of herbivores. Moreover, exogenous application of JA can be used to elicit plant defence responses similar to those

  20. The Transcription Factor ABI4 Is Required for the Ascorbic Acid–Dependent Regulation of Growth and Regulation of Jasmonate-Dependent Defense Signaling Pathways in Arabidopsis[C][W

    Kerchev, Pavel I.; Pellny, Till K.; Vivancos, Pedro Diaz; Kiddle, Guy; Hedden, Peter; Driscoll, Simon; Vanacker, Hélène; Verrier, Paul; Hancock, Robert D.; Foyer, Christine H.

    2011-01-01

    Cellular redox homeostasis is a hub for signal integration. Interactions between redox metabolism and the ABSCISIC ACID-INSENSITIVE-4 (ABI4) transcription factor were characterized in the Arabidopsis thaliana vitamin c defective1 (vtc1) and vtc2 mutants, which are defective in ascorbic acid synthesis and show a slow growth phenotype together with enhanced abscisic acid (ABA) levels relative to the wild type (Columbia-0). The 75% decrease in the leaf ascorbate pool in the vtc2 mutants was not sufficient to adversely affect GA metabolism. The transcriptome signatures of the abi4, vtc1, and vtc2 mutants showed significant overlap, with a large number of transcription factors or signaling components similarly repressed or induced. Moreover, lincomycin-dependent changes in LIGHT HARVESTING CHLOROPHYLL A/B BINDING PROTEIN 1.1 expression were comparable in these mutants, suggesting overlapping participation in chloroplast to nucleus signaling. The slow growth phenotype of vtc2 was absent in the abi4 vtc2 double mutant, as was the sugar-insensitive phenotype of the abi4 mutant. Octadecanoid derivative-responsive AP2/ERF-domain transcription factor 47 (ORA47) and AP3 (an ABI5 binding factor) transcripts were enhanced in vtc2 but repressed in abi4 vtc2, suggesting that ABI4 and ascorbate modulate growth and defense gene expression through jasmonate signaling. We conclude that low ascorbate triggers ABA- and jasmonate-dependent signaling pathways that together regulate growth through ABI4. Moreover, cellular redox homeostasis exerts a strong influence on sugar-dependent growth regulation. PMID:21926335

  1. The role of jasmonates in floral nectar secretion.

    Venkatesan Radhika

    Full Text Available Plants produce nectar in their flowers as a reward for their pollinators and most of our crops depend on insect pollination, but little is known on the physiological control of nectar secretion. Jasmonates are well-known for their effects on senescence, the development and opening of flowers and on plant defences such as extrafloral nectar. Their role in floral nectar secretion has, however, not been explored so far. We investigated whether jasmonates have an influence on floral nectar secretion in oil-seed rape, Brassica napus. The floral tissues of this plant produced jasmonic acid (JA endogenously, and JA concentrations peaked shortly before nectar secretion was highest. Exogenous application of JA to flowers induced nectar secretion, which was suppressed by treatment with phenidone, an inhibitor of JA synthesis. This effect could be reversed by additional application of JA. Jasmonoyl-isoleucine and its structural mimic coronalon also increased nectar secretion. Herbivory or addition of JA to the leaves did not have an effect on floral nectar secretion, demonstrating a functional separation of systemic defence signalling from reproductive nectar secretion. Jasmonates, which have been intensively studied in the context of herbivore defences and flower development, have a profound effect on floral nectar secretion and, thus, pollination efficiency in B. napus. Our results link floral nectar secretion to jasmonate signalling and thereby integrate the floral nectar secretion into the complex network of oxylipid-mediated developmental processes of plants.

  2. Effects of methyl jasmonate, on stevioside and rebaudioside A content and expression of the ent-Kaurenoic acid 13-hydroxylase gene in Stevia rebaudiana Bert. in vitro

    Mehrdad Behmanesh

    2014-08-01

    Full Text Available Glycosides are a form of secondary metabolites that consist variety compounds and in some cases can play a role in primary metabolism. Steviol is lipophilic skeleton of Stevioside and Rebaudioside A, two main glycosides of Stevia rebuadiana. Steviol glycosides which are synthesized in S.rebaudiana have important medical and nutritional values as high intensity natural sweeteners. Steviol is synthesized from Kaurenoic acid in chloroplastic Terpenoid pathway that mediated by Kaurenoic acid 13-hydroxylase. In this study, HPLC method and RT-PCR were performed for quantification of glycosides and gene expression (ent-Kaurenoic acid 13-hydroxylase respectively. Methyl jasmonate treatment (at 20 micromolar in vitro induced glycoside biosynthesis significantly (P≤0.05 whereas higher concentration of Methyl jasmonate (100 µM caused a decrease in glycoside production and growth. The most glycoside content of the plant was three days after treatment. Also Methyl jasmonate treatment caused an increase in ent-Kaurenoic 13-hydroxylase gene expression from 6 hours to 48 hours (after treatment Results showed that biosynthesis of Stevia glycosides was probably a defense mechanism against pathogens and herbivore insects. Also we found that different concentrations of Methyl jasmonate, alter the ratio between glycosides rather than the increase in glycoside contents.

  3. Methyl Jasmonate and Salicylic Acid Induced Oxidative Stress and Accumulation of Phenolics in Panax ginseng Bioreactor Root Suspension Cultures

    Kee-Yoeup Paek

    2007-03-01

    Full Text Available To investigate the enzyme variations responsible for the synthesis of phenolics, 40 day-old adventitious roots of Panax ginseng were treated with 200 μM methyl jasmonate (MJ or salicylic acid (SA in a 5 L bioreactor suspension culture (working volume 4 L. Both treatments caused an increase in the carbonyl and hydrogen peroxide (H2O2 contents, although the levels were lower in SA treated roots. Total phenolic, flavonoid, ascorbic acid, non-protein thiol (NPSH and cysteine contents and 1,1-diphenyl-2-picrylhydrazyl (DPPH radical reducing activity were increased by MJ and SA. Fresh weight (FW and dry weight (DW decreased significantly after 9 days of exposure to SA and MJ. The highest total phenolics (62%, DPPH activity (40%, flavonoids (88%, ascorbic acid (55%, NPSH (33%, and cysteine (62% contents compared to control were obtained after 9 days in SA treated roots. The activities of glucose 6-phosphate dehydrogenase, phenylalanine ammonia lyase, substrate specific peroxidases (caffeic acid peroxidase, quercetin peroxidase and ferulic acid peroxidase were higher in MJ treated roots than the SA treated ones. Increased shikimate dehydrogenase, chlorogenic acid peroxidase and β-glucosidase activities and proline content were observed in SA treated roots than in MJ ones. Cinnamyl alcohol dehydrogenase activity remained unaffected by both MJ and SA. These results strongly indicate that MJ and SA induce the accumulation of phenolic compounds in ginseng root by altering the phenolic synthesis enzymes.

  4. Assessing the Role of ETHYLENE RESPONSE FACTOR Transcriptional Repressors in Salicylic Acid-Mediated Suppression of Jasmonic Acid-Responsive Genes.

    Caarls, Lotte; Van der Does, Dieuwertje; Hickman, Richard; Jansen, Wouter; Verk, Marcel C Van; Proietti, Silvia; Lorenzo, Oscar; Solano, Roberto; Pieterse, Corné M J; Van Wees, Saskia C M

    2017-02-01

    Salicylic acid (SA) and jasmonic acid (JA) cross-communicate in the plant immune signaling network to finely regulate induced defenses. In Arabidopsis, SA antagonizes many JA-responsive genes, partly by targeting the ETHYLENE RESPONSE FACTOR (ERF)-type transcriptional activator ORA59. Members of the ERF transcription factor family typically bind to GCC-box motifs in the promoters of JA- and ethylene-responsive genes, thereby positively or negatively regulating their expression. The GCC-box motif is sufficient for SA-mediated suppression of JA-responsive gene expression. Here, we investigated whether SA-induced ERF-type transcriptional repressors, which may compete with JA-induced ERF-type activators for binding at the GCC-box, play a role in SA/JA antagonism. We selected ERFs that are transcriptionally induced by SA and/or possess an EAR transcriptional repressor motif. Several of the 16 ERFs tested suppressed JA-dependent gene expression, as revealed by enhanced JA-induced PDF1.2 or VSP2 expression levels in the corresponding erf mutants, while others were involved in activation of these genes. However, SA could antagonize JA-induced PDF1.2 or VSP2 in all erf mutants, suggesting that the tested ERF transcriptional repressors are not required for SA/JA cross-talk. Moreover, a mutant in the co-repressor TOPLESS, that showed reduction in repression of JA signaling, still displayed SA-mediated antagonism of PDF1.2 and VSP2. Collectively, these results suggest that SA-regulated ERF transcriptional repressors are not essential for antagonism of JA-responsive gene expression by SA. We further show that de novo SA-induced protein synthesis is required for suppression of JA-induced PDF1.2, pointing to SA-stimulated production of an as yet unknown protein that suppresses JA-induced transcription. © The Author 2016. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  5. BIOSYNTHESIS AND ACTION OF JASMONATES IN PLANTS.

    Creelman, Robert A.; Mullet, John E.

    1997-06-01

    Jasmonic acid and its derivatives can modulate aspects of fruit ripening, production of viable pollen, root growth, tendril coiling, and plant resistance to insects and pathogens. Jasmonate activates genes involved in pathogen and insect resistance, and genes encoding vegetative storage proteins, but represses genes encoding proteins involved in photosynthesis. Jasmonic acid is derived from linolenic acid, and most of the enzymes in the biosynthetic pathway have been extensively characterized. Modulation of lipoxygenase and allene oxide synthase gene expression in transgenic plants raises new questions about the compartmentation of the biosynthetic pathway and its regulation. The activation of jasmonic acid biosynthesis by cell wall elicitors, the peptide systemin, and other compounds will be related to the function of jasmonates in plants. Jasmonate modulates gene expression at the level of translation, RNA processing, and transcription. Promoter elements that mediate responses to jasmonate have been isolated. This review covers recent advances in our understanding of how jasmonate biosynthesis is regulated and relates this information to knowledge of jasmonate modulated gene expression.

  6. α-Ketol linolenic acid (KODA) application affects endogenous abscisic acid, jasmonic acid and aromatic volatiles in grapes infected by a pathogen (Glomerella cingulata).

    Wang, Shanshan; Saito, Takanori; Ohkawa, Katsuya; Ohara, Hitoshi; Shishido, Masahiro; Ikeura, Hiromi; Takagi, Kazuteru; Ogawa, Shigeyuki; Yokoyama, Mineyuki; Kondo, Satoru

    2016-03-15

    Effects of α-ketol linolenic acid (KODA) application on endogenous abscisic acid (ABA), jasmonic acid (JA), and aromatic volatiles were investigated in 'Kyoho' grapes (Vitis labrusca×Vitis vinifera) infected by a pathogen (Glomerella cingulata). The expressions of 9-cis-epoxycarotenoid dioxygenase (VvNCED1), ABA 8'-hydroxylase (VvCYP707A1), lipoxygenase (VvLOX), and allene oxide synthase (VvAOS) were also examined. The grape berries were dipped in 0.1mM KODA solution before inoculation with the pathogen and stored at 25°C for 12 days. The development of infection was significantly suppressed upon KODA treatment. Endogenous ABA, JA and phaseic acid (PA) were induced in inoculated berries. KODA application before inoculation increased endogenous ABA, PA and JA through the activation of VvNCED1, VvCYP707A1 and VvAOS genes, respectively. In addition, terpenes, methyl salicylate (Me-SA) and C6-aldehydes such as (E)-2-hexenal and cis-3-hexenal associated with fungal resistance also increased in KODA-treated berries during storage. These results suggest that the synergistic effect of JA, ABA, and some aromatic volatiles induced by KODA application may provide resistance to pathogen infection in grape berries. Copyright © 2016 Elsevier GmbH. All rights reserved.

  7. Circadian changes in endogenous concentrations of indole-3-acetic acid, melatonin, serotonin, abscisic acid and jasmonic acid in Characeae (Chara australis Brown).

    Beilby, Mary J; Turi, Christina E; Baker, Teesha C; Tymm, Fiona Jm; Murch, Susan J

    2015-01-01

    Giant-celled Characeae (Chara australis Brown), grown for 4 months on 12/12 hr day/night cycle and summer/autumn temperatures, exhibited distinct concentration maxima in auxin (indole-3-acetic acid; IAA), melatonin and serotonin about 4 hr after subjective daybreak. These concentration peaks persisted after 3 day pretreatment in continuous darkness: confirming a circadian rhythm, rather than a response to "light on." The plants pretreated for 3 d in continuous light exhibited several large IAA concentration maxima throughout the 24 hr. The melatonin and serotonin concentrations decreased and were less synchronized with IAA. Chara plants grown on 9/15 hr day/night cycle for 4 months and winter/spring temperatures contained much smaller concentrations of IAA, melatonin and serotonin. The IAA concentration maxima were observed in subjective dark phase. Serotonin concentration peaks were weakly correlated with those of IAA. Melatonin concentration was low and mostly independent of circadian cycle. The "dark" IAA concentration peaks persisted in plants treated for 3 d in the dark. The plants pretreated for 3 d in the light again developed more IAA concentration peaks. In this case the concentration maxima in melatonin and serotonin became more synchronous with those in IAA. The abscisic acid (ABA) and jasmonic acid (JA) concentrations were also measured in plants on winter regime. The ABA concentration did not exhibit circadian pattern, while JA concentration peaks were out of phase with those of IAA. The data are discussed in terms of crosstalk between metabolic pathways.

  8. Jasmonate signaling in plant stress responses and development - active and inactive compounds

    Wasternack, Claus; Strnad, Miroslav

    2016-01-01

    Roč. 33, č. 5 (2016), s. 604-613 ISSN 1871-6784 R&D Projects: GA MŠk(CZ) LO1204 Institutional support: RVO:61389030 Keywords : ALLENE-OXIDE-CYCLASE * BOTRYTIS-CINEREA INFECTION * 12-OXO-PHYTODIENOIC ACID Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 3.813, year: 2016

  9. The Bacterial Effector HopX1 Targets JAZ Transcriptional Repressors to Activate Jasmonate Signaling and Promote Infection in Arabidopsis

    Gimenez-Ibanez, Selena; Boter, Marta; Fernández-Barbero, Gemma; Chini, Andrea; Rathjen, John P.; Solano, Roberto

    2014-01-01

    Pathogenicity of Pseudomonas syringae is dependent on a type III secretion system, which secretes a suite of virulence effector proteins into the host cytoplasm, and the production of a number of toxins such as coronatine (COR), which is a mimic of the plant hormone jasmonate-isoleuce (JA-Ile). Inside the plant cell, effectors target host molecules to subvert the host cell physiology and disrupt defenses. However, despite the fact that elucidating effector action is essential to understanding bacterial pathogenesis, the molecular function and host targets of the vast majority of effectors remain largely unknown. Here, we found that effector HopX1 from Pseudomonas syringae pv. tabaci (Pta) 11528, a strain that does not produce COR, interacts with and promotes the degradation of JAZ proteins, a key family of JA-repressors. We show that hopX1 encodes a cysteine protease, activity that is required for degradation of JAZs by HopX1. HopX1 associates with JAZ proteins through its central ZIM domain and degradation occurs in a COI1-independent manner. Moreover, ectopic expression of HopX1 in Arabidopsis induces the expression of JA-dependent genes, represses salicylic acid (SA)-induced markers, and complements the growth of a COR-deficient P. syringae pv. tomato (Pto) DC3000 strain during natural bacterial infections. Furthermore, HopX1 promoted susceptibility when delivered by the natural type III secretion system, to a similar extent as the addition of COR, and this effect was dependent on its catalytic activity. Altogether, our results indicate that JAZ proteins are direct targets of bacterial effectors to promote activation of JA-induced defenses and susceptibility in Arabidopsis. HopX1 illustrates a paradigm of an alternative evolutionary solution to COR with similar physiological outcome. PMID:24558350

  10. Differential effectiveness of salicylate-dependent and jasmonate/ethylene-dependent induced resistance in Arabidopsis

    Ton, J.; Pelt, J.A. van; Loon, L.C. van; Pieterse, C.M.J.

    2002-01-01

    Salicylic acid (SA), jasmonic acid (JA), and ethylene (ET) are each involved in the regulation of basal resistance against different pathogens. These three signals play important roles in induced resistance as well. SA is a key regulator of pathogen-induced systemic acquired resistance (SAR),

  11. [Content of salicylic and jasmonic acids in pea roots (Pisum sativum L.) at the initial stage of symbiotic or pathogenic interaction with bacteria of the family Rhizobiaceae].

    Rudikovskaya, E G; Akimova, G P; Rudikovskii, A V; Katysheva, N B; Dudareva, L V

    2017-01-01

    A change in the contents of endogenous salicylic and jasmonic acids in the roots of the host plant at the preinfectious stage of interaction with symbiotic (Rhizobium leguminosarum) and pathogenic (Agrobacterium rizogenes) bacteria belonging for to the family Rhizobiaceae was studied. It was found that the jasmonic acid content increased 1.5–2 times 5 min after inoculation with these bacterial species. It was shown that dynamics of the change in the JA and SA contents depends on the type of infection. Thus, the JA content decreased in the case of pathogenesis, while the SA content increased. At the same time, an increased JA content was observed during symbiosis. The observed regularities could indicate the presence of different strategies of hormonal regulation for interaction with symbiotic and pathogenic bacteria belonging to the family Rhizobiaceae in peas plants.

  12. The Mediator subunit SFR6/MED16 controls defence gene expression mediated by salicylic acid and jasmonate responsive pathways.

    Wathugala, Deepthi L; Hemsley, Piers A; Moffat, Caroline S; Cremelie, Pieter; Knight, Marc R; Knight, Heather

    2012-07-01

    • Arabidopsis SENSITIVE TO FREEZING6 (SFR6) controls cold- and drought-inducible gene expression and freezing- and osmotic-stress tolerance. Its identification as a component of the MEDIATOR transcriptional co-activator complex led us to address its involvement in other transcriptional responses. • Gene expression responses to Pseudomonas syringae, ultraviolet-C (UV-C) irradiation, salicylic acid (SA) and jasmonic acid (JA) were investigated in three sfr6 mutant alleles by quantitative real-time PCR and susceptibility to UV-C irradiation and Pseudomonas infection were assessed. • sfr6 mutants were more susceptible to both Pseudomonas syringae infection and UV-C irradiation. They exhibited correspondingly weaker PR (pathogenesis-related) gene expression than wild-type Arabidopsis following these treatments or after direct application of SA, involved in response to both UV-C and Pseudomonas infection. Other genes, however, were induced normally in the mutants by these treatments. sfr6 mutants were severely defective in expression of plant defensin genes in response to JA; ectopic expression of defensin genes was provoked in wild-type but not sfr6 by overexpression of ERF5. • SFR6/MED16 controls both SA- and JA-mediated defence gene expression and is necessary for tolerance of Pseudomonas syringae infection and UV-C irradiation. It is not, however, a universal regulator of stress gene transcription and is likely to mediate transcriptional activation of specific regulons only. © 2012 The Authors. New Phytologist © 2012 New Phytologist Trust.

  13. Jasmonic acid Modulates the Physio-Biochemical Attributes, Antioxidant Enzyme Activity and Gene Expression in Glycine max under Nickel Toxicity

    Geetika eSirhindi

    2016-05-01

    Full Text Available In present study, we evaluated the effects of Jasmonic acid (JA on physio-biochemical attributes, antioxidant enzyme activity and gene expression in soybean (Glycine max L. plants subjected to nickel (Ni stress. Ni stress decreases the shoot and root length and chlorophyll content by 37.23%, 38.31% and 39.21% respectively over the control. However, application of JA was found to improve the chlorophyll content and growth of Ni-stressed seedlings in terms of root and shoot length. Plants supplemented with Jasmonate restores the chlorophyll fluorescence, which was disturbed by Ni stress. The present study demonstrated increase in proline, glycinebetaine, total protein and total soluble sugar (TSS by 33.09%, 51.26%, 22.58% and 49.15% respectively under Ni toxicity as compared to control. Supplementation of JA to Ni stressed plants further enhanced the above parameters. Ni stress increases hydrogen peroxide (H2O2 by 68.49%, lipid peroxidation (MDA by 50.57% and NADPH oxidase by 50.92% over the control. Supplementation of JA minimizes the accumulation of H2O2, MDA and NADPH oxidase, which helps in stabilization of biomolecules. The activities of superoxide dismutase (SOD, peroxidase (POD, catalase (CAT and ascorbate peroxidase (APX increases by 40.04%, 28.22%, 48.53% and 56.79% respectively over the control in Ni treated seedlings and further enhancement in the antioxidant activity was observed by the application of JA. Ni treated soybean seedlings showed increase in expression of Fe-SOD by 77.62%, CAT by 15.25%, POD by 58.33% and APX by 80.58% over the control. Nevertheless, application of JA further enhanced the expression of the above genes in the present study. Our results signified that Ni stress caused negative impacts on soybean seedlings, but, co-application of JA facilitate the seedlings to combat the detrimental effects of Ni through enhanced osmolytes and osmoprotectants, antioxidant enzyme activity and gene expression.

  14. Separate and Combined Response to UV-B Radiation and Jasmonic Acid on Photosynthesis and Growth Characteristics of Scutellaria baicalensis

    Jiaxin Quan

    2018-04-01

    Full Text Available The negative effects of enhanced ultraviolet-B (UV-B on plant growth and development have been reported with many species. Considering the ability of jasmonic acid (JA to improve plant stress tolerance, the hypothesis that JA pretreatment could alleviate the adverse effects of UV-B on S. baicalensis was tested in this study with photosynthesis and growth characteristics. The results showed that UV-B or JA alone both induced photosynthesis inhibition and decreased biomass in stems and leaves. However, the photosynthetic reduction caused by increased UV-B was mainly related to the effect of nonstomatal-limitation, while that of JA was a stomatal-limitation effect. JA pretreatment prior to UV-B could remit the photosynthetic inhibition via the recovery of chlorophyll content, stomatal conductance; and intercellular CO2 concentration (especially the maximum electron transport rate increase. Furthermore, the coaction of JA and enhanced UV-B alleviated some disadvantageous effects on the leaf and did not aggravate the growth damage induced by their separate actions.

  15. Separate and Combined Response to UV-B Radiation and Jasmonic Acid on Photosynthesis and Growth Characteristics of Scutellaria baicalensis.

    Quan, Jiaxin; Song, Shanshan; Abdulrashid, Kadir; Chai, Yongfu; Yue, Ming; Liu, Xiao

    2018-04-13

    The negative effects of enhanced ultraviolet-B (UV-B) on plant growth and development have been reported with many species. Considering the ability of jasmonic acid (JA) to improve plant stress tolerance, the hypothesis that JA pretreatment could alleviate the adverse effects of UV-B on S. baicalensis was tested in this study with photosynthesis and growth characteristics. The results showed that UV-B or JA alone both induced photosynthesis inhibition and decreased biomass in stems and leaves. However, the photosynthetic reduction caused by increased UV-B was mainly related to the effect of nonstomatal-limitation, while that of JA was a stomatal-limitation effect. JA pretreatment prior to UV-B could remit the photosynthetic inhibition via the recovery of chlorophyll content, stomatal conductance; and intercellular CO₂ concentration (especially the maximum electron transport rate increase). Furthermore, the coaction of JA and enhanced UV-B alleviated some disadvantageous effects on the leaf and did not aggravate the growth damage induced by their separate actions.

  16. Dehydration-induced WRKY genes from tobacco and soybean respond to jasmonic acid treatments in BY-2 cell culture.

    Rabara, Roel C; Tripathi, Prateek; Lin, Jun; Rushton, Paul J

    2013-02-15

    Drought is one of the important environmental factors affecting crop production worldwide and therefore understanding the molecular response of plant to stress is an important step in crop improvement. WRKY transcription factors are one of the 10 largest transcription factor families across the green lineage. In this study, highly upregulated dehydration-induced WRKY and enzyme-coding genes from tobacco and soybean were selected from microarray data for promoter analyses. Putative stress-related cis-regulatory elements such as TGACG motif, ABRE-like elements; W and G-like sequences were identified by an in silico analyses of promoter region of the selected genes. GFP quantification of transgenic BY-2 cell culture showed these promoters direct higher expression in-response to 100 μM JA treatment compared to 100 μM ABA, 10% PEG and 85 mM NaCl treatments. Thus promoter activity upon JA treatment and enrichment of MeJA-responsive elements in the promoter of the selected genes provides insights for these genes to be jasmonic acid responsive with potential of mediating cross-talk during dehydration responses. Copyright © 2013 Elsevier Inc. All rights reserved.

  17. Effect of Exogenous Abscisic Acid and Methyl Jasmonate on Anthocyanin Composition, Fatty Acids, and Volatile Compounds of Cabernet Sauvignon (Vitis vinifera L. Grape Berries

    Yan-Lun Ju

    2016-10-01

    Full Text Available The anthocyanin composition, fatty acids, and volatile aromas are important for Cabernet Sauvignon grape quality. This study evaluated the effect of exogenous abscisic acid (ABA and methyl jasmonate (MeJA on the anthocyanin composition, fatty acids, lipoxygenase activity, and the volatile compounds of Cabernet Sauvignon grape berries. Exogenous ABA and MeJA improved the content of total anthocyanins (TAC and individual anthocyanins. Lipoxygenase (LOX activity also increased after treatment. Furthermore, 16 fatty acids were detected. The linoleic acid concentration gradually increased with ABA concentration. The fatty acid content decreased with increasing MeJA concentration and then increased again, with the exception of linoleic acid. After exogenous ABA and MeJA treatment, the C6 aroma content increased significantly. Interestingly, the exogenous ABA and MeJA treatments improved mainly the content of 1-hexanol, hexanal, and 2-heptanol. These results provide insight into the effect of plant hormones on wine grapes, which is useful for grape quality improvement.

  18. In Silico Identification of Mimicking Molecules as Defense Inducers Triggering Jasmonic Acid Mediated Immunity against Alternaria Blight Disease in Brassica Species

    Dinesh Pandey

    2017-04-01

    Full Text Available Alternaria brassicae and Alternaria brassicicola are two major phytopathogenic fungi which cause Alternaria blight, a recalcitrant disease on Brassica crops throughout the world, which is highly destructive and responsible for significant yield losses. Since no resistant source is available against Alternaria blight, therefore, efforts have been made in the present study to identify defense inducer molecules which can induce jasmonic acid (JA mediated defense against the disease. It is believed that JA triggered defense response will prevent necrotrophic mode of colonization of Alternaria brassicae fungus. The JA receptor, COI1 is one of the potential targets for triggering JA mediated immunity through interaction with JA signal. In the present study, few mimicking compounds more efficient than naturally occurring JA in terms of interaction with COI1 were identified through virtual screening and molecular dynamics simulation studies. A high quality structural model of COI1 was developed using the protein sequence of Brassica rapa. This was followed by virtual screening of 767 analogs of JA from ZINC database for interaction with COI1. Two analogs viz. ZINC27640214 and ZINC43772052 showed more binding affinity with COI1 as compared to naturally occurring JA. Molecular dynamics simulation of COI1 and COI1-JA complex, as well as best screened interacting structural analogs of JA with COI1 was done for 50 ns to validate the stability of system. It was found that ZINC27640214 possesses efficient, stable, and good cell permeability properties. Based on the obtained results and its physicochemical properties, it is capable of mimicking JA signaling and may be used as defense inducers for triggering JA mediated resistance against Alternaria blight, only after further validation through field trials.

  19. Bile Acid Metabolism and Signaling

    Chiang, John Y. L.

    2015-01-01

    Bile acids are important physiological agents for intestinal nutrient absorption and biliary secretion of lipids, toxic metabolites, and xenobiotics. Bile acids also are signaling molecules and metabolic regulators that activate nuclear receptors and G protein-coupled receptor (GPCR) signaling to regulate hepatic lipid, glucose, and energy homeostasis and maintain metabolic homeostasis. Conversion of cholesterol to bile acids is critical for maintaining cholesterol homeostasis and preventing accumulation of cholesterol, triglycerides, and toxic metabolites, and injury in the liver and other organs. Enterohepatic circulation of bile acids from the liver to intestine and back to the liver plays a central role in nutrient absorption and distribution, and metabolic regulation and homeostasis. This physiological process is regulated by a complex membrane transport system in the liver and intestine regulated by nuclear receptors. Toxic bile acids may cause inflammation, apoptosis, and cell death. On the other hand, bile acid-activated nuclear and GPCR signaling protects against inflammation in liver, intestine, and macrophages. Disorders in bile acid metabolism cause cholestatic liver diseases, dyslipidemia, fatty liver diseases, cardiovascular diseases, and diabetes. Bile acids, bile acid derivatives, and bile acid sequestrants are therapeutic agents for treating chronic liver diseases, obesity, and diabetes in humans. PMID:23897684

  20. Molecular mechanisms underlying Grateloupia imbricata (Rhodophyta) carposporogenesis induced by methyl jasmonate.

    Garcia-Jimenez, Pilar; Montero-Fernández, Montserrat; Robaina, Rafael R

    2017-12-01

    When applied in vitro, methyl jasmonate is sensed by the red seaweed Grateloupia imbricate, substantially and visually affecting its carposporogenesis. However, although there is some understanding of the morphological changes induced by methyl jasmonate in vitro, little is known about the genes that are involved in red seaweed carposporogenesis and how their protein products act. For the work reported herein, the expression of genes in red seaweed that encode enzymes involved in the synthesis of methyl jasmonate (jasmonic acid carboxyl methyl transferase and a putative methyl transferase) was monitored. Additionally the genes involved in oxidation (cytochrome P450 and WD40), jasmonate synthesis, signal transduction, and regulation of reactive oxygen species (MYB), and reproduction (ornithine decarboxylase) were monitored. To determine when or if the aforementioned genes were expressed during cystocarp development, fertilized and fertile thalli were exposed to methyl jasmonate and gene expression was measured after 24 and 48 h. The results showed that methyl jasmonate promoted differential gene expression in fertilized thalli by 24 h and upregulated expression of the ornithine decarboxylase gene only by 48 h in fertile thalli (0.75 ± 003 copies · μL -1 at 24 h vs. 1.11 ± 0.04 copies · μL -1 at 48 h). We conclude that Ornithine decarboxylase expression involves methyl jasmonate signaling as well as development and maturation of cystocarps. © 2017 Phycological Society of America.

  1. Possible role of jasmonic acid in the regulation of floral induction, evocation and floral differentiation in Lemna minor L.

    Krajncic, B; Kristl, J; Janzekovic, I

    2006-01-01

    Jasmonic acid (JA) is implicated in a wide variety of developmental and physiological processes in plants. Here, we studied the effects of JA and the combination of JA and ethylenediamine-dio-hydroxyphenyl-acetic acid (EDDHA) on flowering in Lemna minor in axenical cultures. JA (0.475-47.5 nmol l(-1)) enhanced floral induction in L. minor under long-day (LD) conditions. Under the same conditions, at a concentration of 237.5 nmol l(-1), JA inhibited floral induction, and at a concentration of 475 nmol l(-1) it prevented floral induction. Under LD conditions with LD preculture, a combination of EDDHA (20,500 nmol l(-1)) and JA (47.5 nmol l(-1)) had a synergistic effect on the promotion of floral induction. Floral induction was enhanced to the greatest extent in experiments with LD precultures. Microscopic examination of microphotographs of histological sections showed that JA and, to an even greater extent, JA+EDDHA at optimal concentrations promote apical floral induction (evocation). Furthermore, JA, and to an even greater extent JA in combination with EDDHA in an optimal concentration, also promote flower differentiation, especially the development of stamens, as is evident from the microphotographs. The experimental results show that JA promotes floral induction in other species of Lemnaceae from various groups according to their photoperiodic response. The results support our hypothesis that, in addition to previously ascribed functions, JA may regulate floral induction, evocation and floral differentiation. Our hypothesis is supported also by the results obtained by quantitative determination of endogenous JA levels in L. minor at three growth stages. The levels of endogenous JA decreased from 389 ng JA g(-1) (fresh weight) of L. minor during the vegetative stage to 217 ng JA g(-1) during the evocation stage, and to 37.5 ng JA g(-1) during the flowering stage, which proves that JA is used for flowering.

  2. Activation of the jasmonic acid pathway by depletion of the hydroperoxide lyase OsHPL3 reveals crosstalk between the HPL and AOS branches of the oxylipin pathway in rice.

    Xiaoqiang Liu

    Full Text Available The allene oxide synthase (AOS and hydroperoxide lyase (HPL branches of the oxylipin pathway, which underlie the production of jasmonates and aldehydes, respectively, function in plant responses to a range of stresses. Regulatory crosstalk has been proposed to exist between these two signaling branches; however, there is no direct evidence of this. Here, we identified and characterized a jasmonic acid (JA overproduction mutant, cea62, by screening a rice T-DNA insertion mutant library for lineages that constitutively express the AOS gene. Map-based cloning was used to identify the underlying gene as hydroperoxide lyase OsHPL3. HPL3 expression and the enzyme activity of its product, (E-2-hexenal, were depleted in the cea62 mutant, which resulted in the dramatic overproduction of JA, the activation of JA signaling, and the emergence of the lesion mimic phenotype. A time-course analysis of lesion formation and of the induction of defense responsive genes in the cea62 mutant revealed that the activation of JA biosynthesis and signaling in cea62 was regulated in a developmental manner, as was OsHPL3 activity in the wild-type plant. Microarray analysis showed that the JA-governed defense response was greatly activated in cea62 and this plant exhibited enhanced resistance to the T1 strain of the bacterial blight pathogen Xanthomonasoryzaepvoryzae (Xoo. The wounding response was attenuated in cea62 plants during the early stages of development, but partially recovered when JA levels were elevated during the later stages. In contrast, the wounding response was not altered during the different developmental stages of wild-type plants. These findings suggest that these two branches of the oxylipin pathway exhibit crosstalk with regards to biosynthesis and signaling and cooperate with each other to function in diverse stress responses.

  3. Enhanced oxidative stress in the jasmonic acid-deficient tomato mutant def-1 exposed to NaCl stress.

    Abouelsaad, Ibrahim; Renault, Sylvie

    2018-04-21

    Jasmonic acid (JA) has been mostly studied in responses to biotic stresses, such as herbivore attack and pathogenic infection. More recently, the involvement of JA in abiotic stresses including salinity was highlighted; yet, its role in salt stress remained unclear. In the current study, we compared the physiological and biochemical responses of wild-type (WT) tomato (Solanum lycopersicum) cv Castlemart and its JA-deficient mutant defenseless-1 (def-1) under salt stress to investigate the role of JA. Plant growth, photosynthetic pigment content, ion accumulation, oxidative stress-related parameters, proline accumulation and total phenolic compounds, in addition to both enzymatic and non-enzymatic antioxidant activities, were measured in both genotypes after 14 days of 100 mM NaCl treatment. Although we observed in both genotypes similar growth pattern and sodium, calcium and potassium levels in leaves under salt stress, def-1 plants exhibited a more pronounced decrease of nitrogen content in both leaves and roots and a slightly higher level of sodium in roots compared to WT plants. In addition, def-1 plants exposed to salt stress showed reactive oxygen species (ROS)-associated injury phenotypes. These oxidative stress symptoms in def-1 were associated with lower activity of both enzymatic antioxidants and non-enzymatic antioxidants. Furthermore, the levels of the non-enzymatic ROS scavengers proline and total phenolic compounds increased in both genotypes exposed to salt stress, with a higher amount of proline in the WT plants. Overall the results of this study suggest that endogenous JA mainly enhanced tomato salt tolerance by maintaining ROS homeostasis. Copyright © 2018 Elsevier GmbH. All rights reserved.

  4. Expression profiling of marker genes responsive to the defence-associated phytohormones salicylic acid, jasmonic acid and ethylene in Brachypodium distachyon.

    Kouzai, Yusuke; Kimura, Mamiko; Yamanaka, Yurie; Watanabe, Megumi; Matsui, Hidenori; Yamamoto, Mikihiro; Ichinose, Yuki; Toyoda, Kazuhiro; Onda, Yoshihiko; Mochida, Keiichi; Noutoshi, Yoshiteru

    2016-03-02

    Brachypodium distachyon is a promising model plants for grasses. Infections of Brachypodium by various pathogens that severely impair crop production have been reported, and the species accordingly provides an alternative platform for investigating molecular mechanisms of pathogen virulence and plant disease resistance. To date, we have a broad picture of plant immunity only in Arabidopsis and rice; therefore, Brachypodium may constitute a counterpart that displays the commonality and uniqueness of defence systems among plant species. Phytohormones play key roles in plant biotic stress responses, and hormone-responsive genes are used to qualitatively and quantitatively evaluate disease resistance responses during pathogen infection. For these purposes, defence-related phytohormone marker genes expressed at time points suitable for defence-response monitoring are needed. Information about their expression profiles over time as well as their response specificity is also helpful. However, useful marker genes are still rare in Brachypodium. We selected 34 candidates for Brachypodium marker genes on the basis of protein-sequence similarity to known marker genes used in Arabidopsis and rice. Brachypodium plants were treated with the defence-related phytohormones salicylic acid, jasmonic acid and ethylene, and their transcription levels were measured 24 and 48 h after treatment. Two genes for salicylic acid, 7 for jasmonic acid and 2 for ethylene were significantly induced at either or both time points. We then focused on 11 genes encoding pathogenesis-related (PR) 1 protein and compared their expression patterns with those of Arabidopsis and rice. Phylogenetic analysis suggested that Brachypodium contains several PR1-family genes similar to rice genes. Our expression profiling revealed that regulation patterns of some PR1 genes as well as of markers identified for defence-related phytohormones are closely related to those in rice. We propose that the Brachypodium immune

  5. Genetic variation in jasmonic acid- and spider mite-induced plant volatile emission of cucumber accessions and attraction of the predator Phytoseiulus persimilis.

    Kappers, Iris F; Verstappen, Francel W A; Luckerhoff, Ludo L P; Bouwmeester, Harro J; Dicke, Marcel

    2010-05-01

    Cucumber plants (Cucumis sativus L.) respond to spider-mite (Tetranychus urticae) damage with the release of specific volatiles that are exploited by predatory mites, the natural enemies of the spider mites, to locate their prey. The production of volatiles also can be induced by exposing plants to the plant hormone jasmonic acid. We analyzed volatile emissions from 15 cucumber accessions upon herbivory by spider mites and upon exposure to jasmonic acid using gas chromatography-mass spectrometry. Upon induction, cucumber plants emitted over 24 different compounds, and the blend of induced volatiles consisted predominantly of terpenoids. The total amount of volatiles was higher in plants treated with jasmonic acid than in those infested with spider mites, with (E)-4,8-dimethyl-1,3,7-nonatriene, (E,E)-alpha-farnesene, and (E)-beta-ocimene as the most abundant compounds in all accessions in both treatments. Significant variation among the accessions was found for the 24 major volatile compounds. The accessions differed strongly in total amount of volatiles emitted, and displayed very different odor profiles. Principal component analysis performed on the relative quantities of particular compounds within the blend revealed clusters of highly correlated volatiles, which is suggestive of common metabolic pathways. A number of cucumber accessions also were tested for their attractiveness to Phytoseiulus persimilis, a specialist predator of spider mites. Differences in the attraction of predatory mites by the various accessions correlated to differences in the individual chemical profiles of these accessions. The presence of genetic variation in induced plant volatile emission in cucumber shows that it is possible to breed for cucumber varieties that are more attractive to predatory mites and other biological control agents.

  6. T3SS-dependent differential modulations of the jasmonic acid pathway in susceptible and resistant genotypes of Malus spp. challenged with Erwinia amylovora.

    Dugé De Bernonville, Thomas; Gaucher, Matthieu; Flors, Victor; Gaillard, Sylvain; Paulin, Jean-Pierre; Dat, James F; Brisset, Marie-Noëlle

    2012-06-01

    Fire blight is a bacterial disease of Maloideae caused by Erwinia amylovora (Ea). This necrogenic enterobacterium uses a type III secretion system (T3SS) to inject type III effectors into the plant cells to cause disease on its susceptible hosts, including economically important crops like apple and pear. The expressions of marker genes of the salicylic acid (SA) and jasmonic acid (JA) defense regulation pathways were monitored by RT-qPCR in leaves of two apple genotypes, one susceptible and one resistant, challenged with a wild type strain, a T3SS-deficient strain or water. The transcriptional data taken together with hormone level measurements indicated that the SA pathway was similarly induced in both apple genotypes during infection by Ea. On the contrary, the data clearly showed a strong T3SS-dependent down-regulation of the JA pathway in leaves of the susceptible genotype but not in those of the resistant one. Accordingly, methyl-jasmonate treated susceptible plants displayed an increased resistance to Ea. Bacterial mutant analysis indicated that JA manipulation by Ea mainly relies on the type III effector DspA/E. Taken together, our data suggest that the T3SS-dependent down-regulation of the JA pathway is a critical step in the infection process of Malus spp. by Ea. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  7. The Active Jasmonate JA-Ile Regulates a Specific Subset of Plant Jasmonate-Mediated Resistance to Herbivores in Nature

    Meredith C. Schuman

    2018-06-01

    Full Text Available The jasmonate hormones are essential regulators of plant defense against herbivores and include several dozen derivatives of the oxylipin jasmonic acid (JA. Among these, the conjugate jasmonoyl isoleucine (JA-Ile has been shown to interact directly with the jasmonate co-receptor complex to regulate responses to jasmonate signaling. However, functional studies indicate that some aspects of jasmonate-mediated defense are not regulated by JA-Ile. Thus, it is not clear whether JA-Ile is best characterized as the master jasmonate regulator of defense, or if it regulates more specific aspects. We investigated possible functions of JA-Ile in anti-herbivore resistance of the wild tobacco Nicotiana attenuata, a model system for plant-herbivore interactions. We first analyzed the soluble and volatile secondary metabolomes of irJAR4xirJAR6, asLOX3, and WT plants, as well as an RNAi line targeting the jasmonate co-receptor CORONATINE INSENSITIVE 1 (irCOI1, following a standardized herbivory treatment. irJAR4xirJAR6 were the most similar to WT plants, having a ca. 60% overlap in differentially regulated metabolites with either asLOX3 or irCOI1. In contrast, while at least 25 volatiles differed between irCOI1 or asLOX3 and WT plants, there were few or no differences in herbivore-induced volatile emission between irJAR4xirJAR6 and WT plants, in glasshouse- or field-collected samples. We then measured the susceptibility of jasmonate-deficient vs. JA-Ile-deficient plants in nature, in comparison to wild-type (WT controls, and found that JA-Ile-deficient plants (irJAR4xirJAR6 are much better defended even than a mildly jasmonate-deficient line (asLOX3. The differences among lines could be attributed to differences in damage from specific herbivores, which appeared to prefer either one or the other jasmonate-deficient phenotype. We further investigated the elicitation of one herbivore-induced volatile known to be jasmonate-regulated and to mediate resistance to

  8. Histone modifications do not play a major role in salicylate-mediated suppression of jasmonate-induced PDF1.2 gene expression

    Koornneef, A.; Rindermann, Katja; Gatz, Christiane; Pieterse, C.M.J.

    2008-01-01

    Cross-talk between salicylic acid (SA) and jasmonic acid (JA) defense signaling pathways allows a plant to finely tune its response to the attacker encountered. In Arabidopsis, pharmacological experiments revealed that SA exerts a strong antagonistic effect on JA-responsive genes, such as PDF1.2,

  9. Salicylic and jasmonic acid pathways are necessary for defence against Dickeya solani as revealed by a novel method for Blackleg disease screening of in vitro grown potato.

    Burra, D D; Mühlenbock, P; Andreasson, E

    2015-09-01

    Potato is major crop ensuring food security in Europe, and blackleg disease is increasingly causing losses in yield and during storage. Recently, one blackleg pathogen, Dickeya solani has been shown to be spreading in Northern Europe that causes aggressive disease development. Currently, identification of tolerant commercial potato varieties has been unsuccessful; this is confounded by the complicated etiology of the disease and a strong environmental influence on disease development. There is currently a lack of efficient testing systems. Here, we describe a system for quantification of blackleg symptoms on shoots of sterile in vitro potato plants, which saves time and space compared to greenhouse and existing field assays. We found no evidence for differences in infection between the described in vitro-based screening method and existing greenhouse assays. This system facilitates efficient screening of blackleg disease response of potato plants independent of other microorganisms and variable environmental conditions. We therefore used the in vitro screening method to increase understanding of plant mechanisms involved in blackleg disease development by analysing disease response of hormone- related (salicylic and jasmonic acid) transgenic potato plants. We show that both jasmonic (JA) and salicylic (SA) acid pathways regulate tolerance to blackleg disease in potato, a result unlike previous findings in Arabidopsis defence response to necrotrophic bacteria. We confirm this by showing induction of a SA marker, pathogenesis-related protein 1 (StPR1), and a JA marker, lipoxygenase (StLOX), in Dickeya solani infected in vitro potato plants. We also observed that tubers of transgenic potato plants were more susceptible to soft rot compared to wild type, suggesting a role for SA and JA pathways in general tolerance to Dickeya. © 2015 German Botanical Society and The Royal Botanical Society of the Netherlands.

  10. Leaf and root glucosinolate profiles of Chinese cabbage (Brassica rapa ssp. pekinensis) as a systemic response to methyl jasmonate and salicylic acid elicitation.

    Zang, Yun-xiang; Ge, Jia-li; Huang, Ling-hui; Gao, Fei; Lv, Xi-shan; Zheng, Wei-wei; Hong, Seung-beom; Zhu, Zhu-jun

    2015-08-01

    Glucosinolates (GSs) are an important group of defensive phytochemicals mainly found in Brassicaceae. Plant hormones jasmonic acid (JA) and salicylic acid (SA) are major regulators of plant response to pathogen attack. However, there is little information about the interactive effect of both elicitors on inducing GS biosynthesis in Chinese cabbage (Brassica rapa ssp. pekinensis). In this study, we applied different concentrations of methyl jasmonate (MeJA) and/or SA onto the leaf and root of Chinese cabbage to investigate the time-course interactive profiles of GSs. Regardless of the site of the elicitation and the concentrations of the elicitors, the roots accumulated much more GSs and were more sensitive and more rapidly responsive to the elicitors than leaves. Irrespective of the elicitation site, MeJA had a greater inducing and longer lasting effect on GS accumulation than SA. All three components of indole GS (IGS) were detected along with aliphatic and aromatic GSs. However, IGS was a major component of total GSs that accumulated rapidly in both root and leaf tissues in response to MeJA and SA elicitation. Neoglucobrassicin (neoGBC) did not respond to SA but to MeJA in leaf tissue, while it responded to both SA and MeJA in root tissue. Conversion of glucobrassicin (GBC) to neoGBC occurred at a steady rate over 3 d of elicitation. Increased accumulation of 4-methoxy glucobrassicin (4-MGBC) occurred only in the root irrespective of the type of elicitors and the site of elicitation. Thus, accumulation of IGS is a major metabolic hallmark of SA- and MeJA-mediated systemic response systems. SA exerted an antagonistic effect on the MeJA-induced root GSs irrespective of the site of elicitation. However, SA showed synergistic and antagonistic effects on the MeJA-induced leaf GSs when roots and leaves are elicitated for 3 d, respectively.

  11. Transcriptome analysis uncovers Arabidopsis F-BOX STRESS INDUCED 1 as a regulator of jasmonic acid and abscisic acid stress gene expression.

    Gonzalez, Lauren E; Keller, Kristen; Chan, Karen X; Gessel, Megan M; Thines, Bryan C

    2017-07-17

    The ubiquitin 26S proteasome system (UPS) selectively degrades cellular proteins, which results in physiological changes to eukaryotic cells. F-box proteins are substrate adaptors within the UPS and are responsible for the diversity of potential protein targets. Plant genomes are enriched in F-box genes, but the vast majority of these have unknown roles. This work investigated the Arabidopsis F-box gene F-BOX STRESS INDUCED 1 (FBS1) for its effects on gene expression in order elucidate its previously unknown biological function. Using publically available Affymetrix ATH1 microarray data, we show that FBS1 is significantly co-expressed in abiotic stresses with other well-characterized stress response genes, including important stress-related transcriptional regulators. This gene suite is most highly expressed in roots under cold and salt stresses. Transcriptome analysis of fbs1-1 knock-out plants grown at a chilling temperature shows that hundreds of genes require FBS1 for appropriate expression, and that these genes are enriched in those having roles in both abiotic and biotic stress responses. Based on both this genome-wide expression data set and quantitative real-time PCR (qPCR) analysis, it is apparent that FBS1 is required for elevated expression of many jasmonic acid (JA) genes that have established roles in combatting environmental stresses, and that it also controls a subset of JA biosynthesis genes. FBS1 also significantly impacts abscisic acid (ABA) regulated genes, but this interaction is more complex, as FBS1 has both positive and negative effects on ABA-inducible and ABA-repressible gene modules. One noteworthy effect of FBS1 on ABA-related stress processes, however, is the restraint it imposes on the expression of multiple class I LIPID TRANSFER PROTEIN (LTP) gene family members that have demonstrated protective effects in water deficit-related stresses. FBS1 impacts plant stress responses by regulating hundreds of genes that respond to the plant

  12. Jasmonates act positively in adventitious root formation in petunia cuttings.

    Lischweski, Sandra; Muchow, Anne; Guthörl, Daniela; Hause, Bettina

    2015-09-22

    Petunia is a model to study the process of adventitious root (AR) formation on leafy cuttings. Excision of cuttings leads to a transient increase in jasmonates, which is regarded as an early, transient and critical event for rooting. Here, the role of jasmonates in AR formation on petunia cuttings has been studied by a reverse genetic approach. To reduce the endogenous levels of jasmonates, transgenic plants were generated expressing a Petunia hybrida ALLENE OXIDE CYCLASE (PhAOC)-RNAi construct. The transgenic plants exhibited strongly reduced PhAOC transcript and protein levels as well as diminished accumulation of cis-12-oxo-phytodienoic acid, jasmonic acid and jasmonoyl-isoleucine after wounding in comparison to wild type and empty vector expressing plants. Reduced levels of endogenous jasmonates resulted in formation of lower numbers of ARs. However, this effect was not accompanied by altered levels of auxin and aminocyclopropane carboxylate (ACC, precursor of ethylene) or by impaired auxin and ethylene-induced gene expression. Neither activity of cell-wall invertases nor accumulation of soluble sugars was altered by jasmonate deficiency. Diminished numbers of AR in JA-deficient cuttings suggest that jasmonates act as positive regulators of AR formation in petunia wild type. However, wound-induced rise in jasmonate levels in petunia wild type cuttings seems not to be causal for increased auxin and ethylene levels and for sink establishment.

  13. Symptomless endophytic fungi suppress endogenous levels of salicylic acid and interact with the jasmonate-dependent indirect defense traits of their host, lima bean (Phaseolus lunatus).

    Navarro-Meléndez, Ariana L; Heil, Martin

    2014-07-01

    Symptomless ‘type II’ fungal endophytes colonize their plant host horizontally and exert diverse effects on its resistance phenotype. Here, we used wild Lima bean (Phaseolus lunatus) plants that were experimentally colonized with one of three strains of natural endophytes (Bartalinia pondoensis, Fusarium sp., or Cochliobolus lunatus) to investigate the effects of fungal colonization on the endogenous levels of salicylic acid (SA) and jasmonic acid (JA) and on two JA-dependent indirect defense traits. Colonization with Fusarium sp. enhanced JA levels in intact leaves, whereas B. pondoensis suppressed the induction of endogenous JA in mechanically damaged leaves. Endogenous SA levels in intact leaves were significantly decreased by all strains and B. pondoensis and Fusarium sp. decreased SA levels after mechanical damage. Colonization with Fusarium sp. or C. lunatus enhanced the number of detectable volatile organic compounds (VOCs) emitted from intact leaves, and all three strains enhanced the relative amount of several VOCs emitted from intact leaves as well as the number of detectable VOCs emitted from slightly damaged leaves. All three strains completely suppressed the induced secretion of extrafloral nectar (EFN) after the exogenous application of JA. Symptomless endophytes interact in complex and strain-specific ways with the endogenous levels of SA and JA and with the defense traits that are controlled by these hormones. These interactions can occur both upstream and downstream of the defense hormones.

  14. Oligogalacturonide-mediated induction of a gene involved in jasmonic acid synthesis in response to the cell-wall-degrading enzymes of the plant pathogen Erwinia carotovora.

    Norman, C; Vidal, S; Palva, E T

    1999-07-01

    Identification of Arabidopsis thaliana genes responsive to plant cell-wall-degrading enzymes of Erwinia carotovora subsp. carotovora led to the isolation of a cDNA clone with high sequence homology to the gene for allene oxide synthase, an enzyme involved in the biosynthesis of jasmonates. Expression of the corresponding gene was induced by the extracellular enzymes from this pathogen as well as by treatment with methyl jasmonate and short oligogalacturonides (OGAs). This suggests that OGAs are involved in the induction of the jasmonate pathway during plant defense response to E. carotovora subsp. carotovora attack.

  15. Priming of seeds with methyl jasmonate induced resistance to hemi-biotroph Fusarium oxysporum f.sp. lycopersici in tomato via 12-oxo-phytodienoic acid, salicylic acid, and flavonol accumulation.

    Król, P; Igielski, R; Pollmann, S; Kępczyńska, E

    2015-05-01

    Methyl jasmonate (MeJA) was tested by seed treatment for its ability to protect tomato seedlings against fusarium wilt caused by the soil-borne fungal pathogen Fusarium oxysporum f.sp. lycopersici. Isolated from Solanum lycopersicon L. seeds, cv. Beta fungus was identified as F. oxysporum f.sp. lycopersici Race 3 fungus by using phytopathological and molecular methods. MeJA applied at 0.01, 0.1 and 1 mM reduced spore germination and mycelial growth in vitro. Soaking of tomato seeds in MeJA solution at 0.1 mM for 1 h significantly enhanced the resistance level against the tested fungus in tomato seedlings 4 weeks after inoculation. The extracts from leaves of 15-day-old seedlings obtained from previously MeJA soaked seeds had the ability to inhibit in vitro spore germination of tested fungus. In these seedlings a significant increase in the levels phenolic compounds such as salicylic acid (SA), kaempferol and quercetin was observed. Up-regulation of phenylalanine ammonia-lyase (PAL5) and benzoic acid/salicylic acid carboxyl methyltransferase (BSMT) genes and down-regulation of the isochorysmate synthase (ICS) gene in response to exogenous MeJA application indicate that the phenylalanine ammonia-lyase (PAL), not the isochorismate (IC) pathway, is the primary route for SA production in tomato. Moreover, the increased accumulation of the flavonols quercetin and kaempferol appears closely related to the increase of PAL5, chalcone synthase (CHS) and flavonol synthase/flavanone 3-hydroxylase-like (FLS) genes. Elevated levels of salicylic acid in seedlings raised from MeJA-soaked seeds were simultaneously accompanied by a decrease of jasmonic acid, the precursor of MeJA, and an increase of 12-oxo-phytodienoic acid (OPDA), the precursor of jasmonic acid. The present results indicate that the priming of tomato seeds with 0.1mM MeJA before sowing enables the seedlings grown from these seeds to reduce the attack of the soil-borne fungal pathogen F. oxysporum f.sp. lycopersici

  16. The pearl millet mitogen-activated protein kinase PgMPK4 is involved in responses to downy mildew infection and in jasmonic- and salicylic acid-mediated defense.

    Melvin, Prasad; Prabhu, S Ashok; Veena, Mariswamy; Shailasree, Sekhar; Petersen, Morten; Mundy, John; Shetty, Shekar H; Kini, K Ramachandra

    2015-02-01

    Plant mitogen-activated protein kinases (MPKs) transduce signals required for the induction of immunity triggered by host recognition of pathogen-associated molecular patterns. We isolated a full-length cDNA of a group B MPK (PgMPK4) from pearl millet. Autophosphorylation assay of recombinant PgMPK4 produced in Escherichia coli confirmed it as a kinase. Differential accumulation of PgMPK4 mRNA and kinase activity was observed between pearl millet cultivars 852B and IP18292 in response to inoculation with the downy mildew oomycete pathogen Sclerospora graminicola. This increased accumulation of PgMPK4 mRNA, kinase activity as well as nuclear-localization of PgMPK protein(s) was only detected in the S. graminicola resistant cultivar IP18292 with a ~tenfold peak at 9 h post inoculation. In the susceptible cultivar 852B, PgMPK4 mRNA and immuno-detectable nuclear PgMPK could be induced by application of the chemical elicitor β-amino butyric acid, the non-pathogenic bacteria Pseudomonas fluorescens, or by the phytohormones jasmonic acid (JA) or salicylic acid (SA). Furthermore, kinase inhibitor treatments indicated that PgMPK4 is involved in the JA- and SA-mediated expression of three defense genes, lipoxygenase, catalase 3 and polygalacturonase-inhibitor protein. These findings indicate that PgMPK/s contribute to pearl millet defense against the downy mildew pathogen by activating the expression of defense proteins.

  17. Oxidative defence reactions in sunflower roots induced by methyl-jasmonate and methyl-salicylate and their relation with calcium signalling.

    Garrido, Inmaculada; Espinosa, Francisco; Alvarez-Tinaut, M Carmen

    2009-10-01

    Ca(2+) plays a critical role as second messenger in the signal-response coupling of plant defence responses, and methyl-jasmonate and methyl-salicylate are important components of signal transduction cascades activating plant defences. When intact axenic non-induced seedling roots of sunflower were treated with different Ca(2+) concentrations up to 1 mM, there was no significant increase in O(2)(*-) generation or DMAB-MBTH peroxidase (extracellular, ECPOX) activities in the apoplast, probably because these roots had enough Ca(2+) in their exo- and endocellular reservoirs. Both activities were strongly inhibited by the RBOH-NADPH oxidase inhibitor DPI and by the Ca(2+) surrogate antagonist La(3+), but the voltage-dependent Ca(2+) channel blocker verapamil was only inhibitory at concentrations higher than those active on animal L-type Ca(2+) channels. Concentrations >5 mM EGTA (chelating Ca(2+) in the apoplast) and Li(+) (inhibiting PI cycle dependent endogenous Ca(2+) fluxes) also inhibited both activities. W7, inhibitor of binding of Ca-CaM to its target protein, enhanced both activities, but the inactive analogue W5 showed a similar effect. Our data suggest that Ca(2+) from exocellular and, to a lesser extent, from endocellular stores is involved in oxidative activities, and that RBOH-NADPH oxidase is the main system supporting them. Ca(2+) activation of the PM cytosolic side of RBOH-NADPH oxidase is probably the key to Ca(2+) involvement in these processes. Roots induced by MeJA or MeSA showed significant enhancement of both oxidative activities, as corresponding to the oxidative burst evoked by the two phytohormones in the root apoplast. But while ECPOX activity showed a response to the effectors similar to that described above for non-induced roots, O(2)(*-) generation activity in the apoplast of induced roots was insensitive to EGTA, verapamil and Li(+), the inhibitors of exogenous and endogenous Ca(2+) fluxes; only DPI and La(3+) were inhibitory. As

  18. Effect of jasmonic acid elicitation on the yield, chemical composition, and antioxidant and anti-inflammatory properties of essential oil of lettuce leaf basil (Ocimum basilicum L.).

    Złotek, Urszula; Michalak-Majewska, Monika; Szymanowska, Urszula

    2016-12-15

    The effect of elicitation with jasmonic acid (JA) on the plant yield, the production and composition of essential oils of lettuce leaf basil was evaluated. JA-elicitation slightly affected the yield of plants and significantly increased the amount of essential oils produced by basil - the highest oil yield (0.78±0.005mL/100gdw) was achieved in plants elicited with 100μM JA. The application of the tested elicitor also influenced the chemical composition of basil essential oils - 100μM JA increased the linalool, eugenol, and limonene levels, while 1μM JA caused the highest increase in the methyl eugenol content. Essential oils from JA-elicited basil (especially 1μM and 100μM) exhibited more effective antioxidant and anti-inflammatory potential; therefore, this inducer may be a very useful biochemical tool for improving production and composition of herbal essential oils. Copyright © 2016 Elsevier Ltd. All rights reserved.

  19. Arabidopsis thaliana cdd1 mutant uncouples the constitutive activation of salicylic acid signalling from growth defects.

    Swain, Swadhin; Roy, Shweta; Shah, Jyoti; Van Wees, Saskia; Pieterse, Corné M; Nandi, Ashis K

    2011-12-01

    Arabidopsis genotypes with a hyperactive salicylic acid-mediated signalling pathway exhibit enhanced disease resistance, which is often coupled with growth and developmental defects, such as dwarfing and spontaneous necrotic lesions on the leaves, resulting in reduced biomass yield. In this article, we report a novel recessive mutant of Arabidopsis, cdd1 (constitutive defence without defect in growth and development1), that exhibits enhanced disease resistance associated with constitutive salicylic acid signalling, but without any observable pleiotropic phenotype. Both NPR1 (NON-EXPRESSOR OF PATHOGENESIS-RELATED GENES1)-dependent and NPR1-independent salicylic acid-regulated defence pathways are hyperactivated in cdd1 mutant plants, conferring enhanced resistance against bacterial pathogens. However, a functional NPR1 allele is required for the cdd1-conferred heightened resistance against the oomycete pathogen Hyaloperonospora arabidopsidis. Salicylic acid accumulates at elevated levels in cdd1 and cdd1 npr1 mutant plants and is necessary for cdd1-mediated PR1 expression and disease resistance phenotypes. In addition, we provide data which indicate that the cdd1 mutation negatively regulates the npr1 mutation-induced hyperactivation of ethylene/jasmonic acid signalling. © 2011 The Authors. Molecular Plant Pathology © 2011 BSPP and Blackwell Publishing Ltd.

  20. Jasmonic Acid Is a Key Regulator of Spider Mite-Induced Volatile Terpenoid and Methyl Salicylate Emission in Tomato1[w

    Ament, Kai; Kant, Merijn R.; Sabelis, Maurice W.; Haring, Michel A.; Schuurink, Robert C.

    2004-01-01

    The tomato (Lycopersicon esculentum) mutant def-1, which is deficient in induced jasmonic acid (JA) accumulation upon wounding or herbivory, was used to study the role of JA in the direct and indirect defense responses to phytophagous mites (Tetranychus urticae). In contrast to earlier reports, spider mites laid as many eggs and caused as much damage on def-1 as on wild-type plants, even though def-1 lacked induction of proteinase inhibitor activity. However, the hatching-rate of eggs on def-1 was significantly higher, suggesting that JA-dependent direct defenses enhanced egg mortality or increased the time needed for embryonic development. As to gene expression, def-1 had lower levels of JA-related transcripts but higher levels of salicylic acid (SA) related transcripts after 1 d of spider mite infestation. Furthermore, the indirect defense response was absent in def-1, since the five typical spider mite-induced tomato-volatiles (methyl salicylate [MeSA], 4,8,12-trimethyltrideca-1,3,7,11-tetraene [TMTT], linalool, trans-nerolidol, and trans-β-ocimene) were not induced and the predatory mite Phytoseiulus persimilis did not discriminate between infested and uninfested def-1 tomatoes as it did with wild-type tomatoes. Similarly, the expression of the MeSA biosynthetic gene salicylic acid methyltransferase (SAMT) was induced by spider mites in wild type but not in def-1. Exogenous application of JA to def-1 induced the accumulation of SAMT and putative geranylgeranyl diphosphate synthase transcripts and restored MeSA- and TMTT-emission upon herbivory. JA is therefore necessary to induce the enzymatic conversion of SA into MeSA. We conclude that JA is essential for establishing the spider mite-induced indirect defense response in tomato. PMID:15310835

  1. Host perception of jasmonates promotes infection by Fusarium oxysporum formae speciales that produce isoleucine- and leucine-conjugated jasmonates.

    Cole, Stephanie J; Yoon, Alexander J; Faull, Kym F; Diener, Andrew C

    2014-08-01

    Three pathogenic forms, or formae speciales (f. spp.), of Fusarium oxysporum infect the roots of Arabidopsis thaliana below ground, instigating symptoms of wilt disease in leaves above ground. In previous reports, Arabidopsis mutants that are deficient in the biosynthesis of abscisic acid or salicylic acid or insensitive to ethylene or jasmonates exhibited either more or less wilt disease, than the wild-type, implicating the involvement of hormones in the normal host response to F. oxysporum. Our analysis of hormone-related mutants finds no evidence that endogenous hormones contribute to infection in roots. Mutants that are deficient in abscisic acid and insensitive to ethylene show no less infection than the wild-type, although they exhibit less disease. Whether a mutant that is insensitive to jasmonates affects infection depends on which forma specialis (f. sp.) is infecting the roots. Insensitivity to jasmonates suppresses infection by F. oxysporum f. sp. conglutinans and F. oxysporum f. sp. matthioli, which produce isoleucine- and leucine-conjugated jasmonate (JA-Ile/Leu), respectively, in culture filtrates, whereas insensitivity to jasmonates has no effect on infection by F. oxysporum f. sp. raphani, which produces no detectable JA-Ile/Leu. Furthermore, insensitivity to jasmonates has no effect on wilt disease of tomato, and the tomato pathogen F. oxysporum f. sp. lycopersici produces no detectable jasmonates. Thus, some, but not all, F. oxysporum pathogens appear to utilize jasmonates as effectors, promoting infection in roots and/or the development of symptoms in shoots. Only when the infection of roots is promoted by jasmonates is wilt disease enhanced in a mutant deficient in salicylic acid biosynthesis. © 2014 BSPP AND JOHN WILEY & SONS LTD.

  2. Necrotrophic pathogens use the salicylic acid signaling pathway to promote disease development in tomato.

    Rahman, Taha Abd El; Oirdi, Mohamed El; Gonzalez-Lamothe, Rocio; Bouarab, Kamal

    2012-12-01

    Plants use different immune pathways to combat pathogens. The activation of the jasmonic acid (JA)-signaling pathway is required for resistance against necrotrophic pathogens; however, to combat biotrophic pathogens, the plants activate mainly the salicylic acid (SA)-signaling pathway. SA can antagonize JA signaling and vice versa. NPR1 (noninducible pathogenesis-related 1) is considered a master regulator of SA signaling. NPR1 interacts with TGA transcription factors, ultimately leading to the activation of SA-dependent responses. SA has been shown to promote disease development caused by the necrotrophic pathogen Botrytis cinerea through NPR1, by suppressing the expression of two JA-dependent defense genes, proteinase inhibitors I and II. We show here that the transcription factor TGA1.a contributes to disease development caused by B. cinerea in tomato by suppressing the expression of proteinase inhibitors I and II. Finally, we present evidence that the SA-signaling pathway contributes to disease development caused by another necrotrophic pathogen, Alternaria solani, in tomato. Disease development promoted by SA through NPR1 requires the TGA1.a transcription factor. These data highlight how necrotrophs manipulate the SAsignaling pathway to promote their disease in tomato.

  3. Cross-talk in abscisic acid signaling

    Fedoroff, Nina V.

    2002-01-01

    "Cross-talk" in hormone signaling reflects an organism's ability to integrate different inputs and respond appropriately, a crucial function at the heart of signaling network operation. Abscisic acid (ABA) is a plant hormone involved in bud and seed dormancy, growth regulation, leaf senescence and abscission, stomatal opening, and a variety of plant stress responses. This review summarizes what is known about ABA signaling in the control of stomatal opening and seed dormancy and provides an overview of emerging knowledge about connections between ABA, ethylene, sugar, and auxin synthesis and signaling.

  4. Salicylic acid-independent plant defence pathways

    Pieterse, C.M.J.; Loon, L.C. van

    1999-01-01

    Salicylic acid is an important signalling molecule involved in both locally and systemically induced disease resistance responses. Recent advances in our understanding of plant defence signalling have revealed that plants employ a network of signal transduction pathways, some of which are independent of salicylic acid. Evidence is emerging that jasmonic acid and ethylene play key roles in these salicylic acid-independent pathways. Cross-talk between the salicylic acid-dependent and the salicy...

  5. Jasmonate is involved in the induction of tyrosine aminotransferase and tocopherol biosynthesis in Arabidopsis thaliana.

    Sandorf, Iris; Holländer-Czytko, Heike

    2002-11-01

    Coronatine-inducible tyrosine aminotransferase (TAT), which catalyses the transamination from tyrosine to p-hydroxyphenylpyruvate, is the first enzyme of a pathway leading via homogentisic acid to plastoquinone and tocopherols, the latter of which are known to be radical scavengers in plants. TAT can be also induced by the octadecanoids methyl jasmonate (MeJA) and methyl-12-oxophytodienoic acid (MeOPDA), as well as by wounding, high light, UV light and the herbicide oxyfluorfen. In order to elucidate the role of octadecanoids in the process of TAT induction in Arabidopsis thaliana (L.) Heynh., the jasmonate-deficient mutant delayed dehiscence (dde1) was used, in which the gene for 12-oxophytodienoic acid reductase 3 is disrupted. The amount of immunodetectable TAT was low. The enzyme was still fully induced by coronatine as well as by MeJA although induction by the latter was to a lesser extent and later than in the wild type. Treatment with MeOPDA, wounding and UV light, however, had hardly any effects. Tocopherol levels that showed considerable increases in the wild type after some treatments were much less affected in the mutant. However, starting levels of tocopherol were higher in non-induced dde1 than in the wild type. We conclude that jasmonate plays an important role in the signal transduction pathway regulating TAT activity and the biosynthesis of its product tocopherol.

  6. Exogenous Methyl Jasmonate and Salicylic Acid Induce Subspecies-Specific Patterns of Glucosinolate Accumulation and Gene Expression in Brassica oleracea L.

    Yi, Go-Eun; Robin, Arif Hasan Khan; Yang, Kiwoung; Park, Jong-In; Hwang, Byung Ho; Nou, Ill-Sup

    2016-10-24

    Glucosinolates have anti-carcinogenic properties. In the recent decades, the genetics of glucosinolate biosynthesis has been widely studied, however, the expression of specific genes involved in glucosinolate biosynthesis under exogenous phytohormone treatment has not been explored at the subspecies level in Brassica oleracea . Such data are vital for strategies aimed at selective exploitation of glucosinolate profiles. This study quantified the expression of 38 glucosinolate biosynthesis-related genes in three B. oleracea subspecies, namely cabbage, broccoli and kale, and catalogued associations between gene expression and increased contents of individual glucosinolates under methyl jasmonate (MeJA) and salicylic acid (SA) treatments. Glucosinolate accumulation and gene expression in response to phytohormone elicitation was subspecies specific. For instance, cabbage leaves showed enhanced accumulation of the aliphatic glucoiberin, progoitrin, sinigrin and indolic neoglucobrassicin under both MeJA and SA treatment. MeJA treatment induced strikingly higher accumulation of glucobrassicin (GBS) in cabbage and kale and of neoglucobrassicin (NGBS) in broccoli compared to controls. Notably higher expression of ST5a (Bol026200), CYP81F1 (Bol028913, Bol028914) and CYP81F4 genes was associated with significantly higher GBS accumulation under MeJA treatment compared to controls in all three subspecies. CYP81F4 genes, trans-activated by MYB34 genes, were expressed at remarkably high levels in all three subspecies under MeJA treatment, which also induced in higher indolic NGBS accumulation in all three subspecies. Remarkably higher expression of MYB28 (Bol036286), ST5b , ST5c , AOP2 , FMOGS-OX5 (Bol031350) and GSL-OH (Bol033373) was associated with much higher contents of aliphatic glucosinolates in kale leaves compared to the other two subspecies. The genes expressed highly could be utilized in strategies to selectively increase glucosinolate compounds in B. oleracea

  7. Cloning of genes related to aliphatic glucosinolate metabolism and the mechanism of sulforaphane accumulation in broccoli sprouts under jasmonic acid treatment.

    Guo, Liping; Yang, Runqiang; Gu, Zhenxin

    2016-10-01

    Cytochrome P450 79F1 (CYP79F1), cytochrome P450 83A1 (CYP83A1), UDP-glucosyltransferase 74B1 (UGT74B1), sulfotransferase 18 (ST5b) and flavin-containing monooxygenase GS-OX1 (FMOGS - OX1 ) are important enzymes in aliphatic glucosinolate biosynthesis. In this study, their full-length cDNA in broccoli was firstly cloned, then the mechanism of sulforaphane accumulation under jasmonic acid (JA) treatment was investigated. The full-length cDNA of CYP79F1, CYP83A1, UGT74B1, ST5b and FMOGS - OX1 comprised 1980, 1652, 1592, 1378 and 1623 bp respectively. The increase in aliphatic glucosinolate accumulation in broccoli sprouts treated with JA was associated with elevated expression of genes in the aliphatic glucosinolate biosynthetic pathway. Application of 100 µmol L(-1) JA increased myrosinase (MYR) activity but did not affect epithiospecifier protein (ESP) activity in broccoli sprouts, which was supported by the expression of MYR and ESP. Sulforaphane formation in 7-day-old sprouts treated with 100 µmol L(-1) JA was 3.36 and 1.30 times that in the control and 300 µmol L(-1) JA treatment respectively. JA enhanced the accumulation of aliphatic glucosinolates in broccoli sprouts via up-regulation of related gene expression. Broccoli sprouts treated with 100 µmol L(-1) JA showed higher sulforphane formation than those treated with 300 µmol L(-1) JA owing to the higher glucoraphanin content and myrosinase activity under 100 µmol L(-1) JA treatment. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  8. Physiological and Proteomic Analysis of the Rice Mutant cpm2 Suggests a Negative Regulatory Role of Jasmonic Acid in Drought Tolerance

    Rohit Dhakarey

    2017-11-01

    Full Text Available It is widely known that numerous adaptive responses of drought-stressed plants are stimulated by chemical messengers known as phytohormones. Jasmonic acid (JA is one such phytohormone. But there are very few reports revealing its direct implication in drought related responses or its cross-talk with other phytohormones. In this study, we compared the morpho-physiological traits and the root proteome of a wild type (WT rice plant with its JA biosynthesis mutant coleoptile photomorphogenesis 2 (cpm2, disrupted in the allene oxide cyclase (AOC gene, for insights into the role of JA under drought. The mutant had higher stomatal conductance, higher water use efficiency and higher shoot ABA levels under severe drought as compared to the WT. Notably, roots of cpm2 were better developed compared to the WT under both, control and drought stress conditions. Root proteome was analyzed using the Tandem Mass Tag strategy to better understand this difference at the molecular level. Expectedly, AOC was unique but notably highly abundant under drought in the WT. Identification of other differentially abundant proteins (DAPs suggested increased energy metabolism (i.e., increased mobilization of resources and reactive oxygen species scavenging in cpm2 under drought. Additionally, various proteins involved in secondary metabolism, cell growth and cell wall synthesis were also more abundant in cpm2 roots. Proteome-guided transcript, metabolite, and histological analyses provided further insights into the favorable adaptations and responses, most likely orchestrated by the lack of JA, in the cpm2 roots. Our results in cpm2 are discussed in the light of JA crosstalk to other phytohormones. These results together pave the path for understanding the precise role of JA during drought stress in rice.

  9. Effects of jasmonic acid, ethylene, and salicylic acid signaling on the rhizosphere bacterial community of Arabidopsis thaliana.

    Doornbos, R.F.; Geraats, B.P.J.; Kuramae, E.E.; van Loon, L.C.; Bakker, P.

    2011-01-01

    Systemically induced resistance is a promising strategy to control plant diseases, as it affects numerous pathogens. However, since induced resistance reduces one or both growth and activity of plant pathogens, the indigenous microflora may also be affected by an enhanced defensive state of the

  10. Changes in actin dynamics are involved in salicylic acid signaling pathway.

    Matoušková, Jindřiška; Janda, Martin; Fišer, Radovan; Sašek, Vladimír; Kocourková, Daniela; Burketová, Lenka; Dušková, Jiřina; Martinec, Jan; Valentová, Olga

    2014-06-01

    Changes in actin cytoskeleton dynamics are one of the crucial players in many physiological as well as non-physiological processes in plant cells. Positioning of actin filament arrays is necessary for successful establishment of primary lines of defense toward pathogen attack, depolymerization leads very often to the enhanced susceptibility to the invading pathogen. On the other hand it was also shown that the disruption of actin cytoskeleton leads to the induction of defense response leading to the expression of PATHOGENESIS RELATED proteins (PR). In this study we show that pharmacological actin depolymerization leads to the specific induction of genes in salicylic acid pathway but not that involved in jasmonic acid signaling. Life imaging of leafs of Arabidopsis thaliana with GFP-tagged fimbrin (GFP-fABD2) treated with 1 mM salicylic acid revealed rapid disruption of actin filaments resembling the pattern viewed after treatment with 200 nM latrunculin B. The effect of salicylic acid on actin filament fragmentation was prevented by exogenous addition of phosphatidic acid, which binds to the capping protein and thus promotes actin polymerization. The quantitative evaluation of actin filament dynamics is also presented. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  11. Abscisic Acid and Abiotic Stress Signaling

    Tuteja, Narendra

    2007-01-01

    Abiotic stress is severe environmental stress, which impairs crop production on irrigated land worldwide. Overall, the susceptibility or tolerance to the stress in plants is a coordinated action of multiple stress responsive genes, which also cross-talk with other components of stress signal transduction pathways. Plant responses to abiotic stress can be determined by the severity of the stress and by the metabolic status of the plant. Abscisic acid (ABA) is a phytohormone critical for plant ...

  12. Proteomic analysis of JAZ interacting proteins under methyl jasmonate treatment in finger millet.

    Sen, Saswati; Kundu, Sangeeta; Dutta, Samir Kr

    2016-11-01

    Jasmonic acid (JA) signaling pathway in plants is activated against various developmental processes as well as biotic and abiotic stresses. The Jasmonate ZIM-domain (JAZ) protein family, the key regulator of plant JA signaling pathway, also participates in phytohormone crosstalk. This is the first study revealing the in vivo interactions of finger millet (Eleusine coracana (L.) Gaertn.) JAZ protein (EcJAZ) under methyl jasmonate (MJ) treatment. The aim of the study was to explore not only the JA signaling pathway but also the phytohormone signaling crosstalk of finger millet, a highly important future crop. From the MJ-treated finger millet seedlings, the EcJAZ interacting proteins were purified by affinity chromatography with the EcJAZ-matrix. Twenty-one proteins of varying functionalities were successfully identified by MALDI-TOF-TOF Mass spectrometry. Apart from the previously identified JAZ binding proteins, most prominently, EcJAZ was found to interact with transcription factors like NAC, GATA and also with Cold responsive protein (COR), etc. that might have extended the range of functionalities of JAZ proteins. Moreover, to evaluate the interactions of EcJAZ in the JA-co-receptor complex, we generated ten in-silico models containing the EcJAZ degron and the COI1-SKP1 of five monocot cereals viz., rice, wheat, maize, Sorghum and Setaria with JA-Ile or coronatine. Our results indicated that the EcJAZ protein of finger millet could act as the signaling hub for the JA and other phytohormone signaling pathways, in response to a diverse set of stressors and developmental cues to provide survival fitness to the plant. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  13. Transcriptomic profiling of linolenic acid-responsive genes in ROS signalling from RNA-seq data in Arabidopsis

    Capilla eMata-Pérez

    2015-03-01

    Full Text Available Linolenic acid (Ln released from chloroplast membrane galactolipids is a precursor of the phytohormone jasmonic acid (JA. The involvement of this hormone in different plant biological processes, such as responses to biotic stress conditions, has been extensively studied. However, the role of Ln in the regulation of gene expression during abiotic stress situations mediated by cellular redox changes and/or by oxidative stress processes remains poorly understood. An RNA-seq approach has increased our knowledge of the interplay among Ln, oxidative stress and ROS signalling that mediates abiotic stress conditions. Transcriptome analysis with the aid of RNA-seq in the absence of oxidative stress revealed that the incubation of Arabidopsis thaliana cell suspension cultures (ACSC with Ln resulted in the modulation of 7525 genes, of which 3034 genes had a 2 fold-change, being 533 up- and 2501 down-regulated genes, respectively. Thus, RNA-seq data analysis showed that an important set of these genes were associated with the jasmonic acid biosynthetic pathway including lypoxygenases (LOXs and Allene oxide cyclases (AOCs. In addition, several transcription factor families involved in the response to biotic stress conditions (pathogen attacks or herbivore feeding, such as WRKY, JAZ, MYC and LRR were also modified in response to Ln. However, this study also shows that Ln has the capacity to modulate the expression of genes involved in the response to abiotic stress conditions, particularly those mediated by ROS signalling. In this regard, we were able to identify new targets such as galactinol synthase 1 (GOLS1, methionine sulfoxide reductase (MSR and alkenal reductase in ACSC. It is therefore possible to suggest that, in the absence of any oxidative stress, Ln is capable of modulating new sets of genes involved in the signalling mechanism mediated by additional abiotic stresses (salinity, UV and high light intensity and especially in stresses mediated by ROS.

  14. Signal signature and transcriptome changes of Arabidopsis during pathogen and insect attack

    Vos, M. de; Oosten, V.R. van; Poecke, R.M.P. van; Pelt, J.A. van; Pozo, Maria J.; Mueller, M.J.; Buchala, A.J.; Métraux, J.P.; Loon, L.C. van; Dicke, M.; Pieterse, C.M.J.

    2005-01-01

    Plant defenses against pathogens and insects are regulated differentially by cross-communicating signaling pathways in which salicylic acid (SA), jasmonic acid (JA), and ethylene (ET) play key roles. To understand how plants integrate pathogen- and insect-induced signals into specific

  15. Signal signature and transcriptome changes of Arabidopsis during pathogen and insect attack

    Vos, de M.; Oosten, van V.R.; Poecke, van R.M.P.; Pelt, van J.A.; Pozo, M.J.; Mueller, M.J.; Buchala, A.J.; Métraux, J.P.; Loon, van L.C.; Dicke, M.; Pieterse, C.M.J.

    2005-01-01

    Plant defenses against pathogens and insects are regulated differentially by cross-communicating signaling pathways in which salicylic acid (SA), jasmonic acid (JA), and ethylene (ET) play key roles. To understand how plants integrate pathogen- and insect-induced signals into specific defense

  16. Chitosan oligosaccharide induces resistance to Tobacco mosaic virus in Arabidopsis via the salicylic acid-mediated signalling pathway.

    Jia, Xiaochen; Meng, Qingshan; Zeng, Haihong; Wang, Wenxia; Yin, Heng

    2016-05-18

    Chitosan is one of the most abundant carbohydrate biopolymers in the world, and chitosan oligosaccharide (COS), which is prepared from chitosan, is a plant immunity regulator. The present study aimed to validate the effect of COS on inducing resistance to tobacco mosaic virus (TMV) in Arabidopsis and to investigate the potential defence-related signalling pathways involved. Optimal conditions for the induction of TMV resistance in Arabidopsis were COS pretreatment at 50 mg/L for 1 day prior to inoculation with TMV. Multilevel indices, including phenotype data, and TMV coat protein expression, revealed that COS induced TMV resistance in wild-type and jasmonic acid pathway- deficient (jar1) Arabidopsis plants, but not in salicylic acid pathway deficient (NahG) Arabidopsis plants. Quantitative-PCR and analysis of phytohormone levels confirmed that COS pretreatment enhanced the expression of the defence-related gene PR1, which is a marker of salicylic acid signalling pathway, and increased the amount of salicylic acid in WT and jar1, but not in NahG plants. Taken together, these results confirm that COS induces TMV resistance in Arabidopsis via activation of the salicylic acid signalling pathway.

  17. Laser signals' nonlinear change in fatty acids

    Ghelmez-Dumitru, M; Piscureanu, M; Sterian, A

    2003-01-01

    Previous works showed that thin layers of fatty acids and fatty acid-cholesterol mixtures behaved as optical liquid crystals, even at low incident laser power. The paper presents an experimental and computer study of laser signals, emergent from such samples, in presence of fluctuations. The optical emergent laser beams' features at different incident parameters were experimentally determined for different type (c.w. and pulsed) lasers, as for example helium-neon and Nd sup 3 sup + glass lasers. The results were correlated with the amount of cholesterol in mixtures and with their response in external electric field. These measurements are in all cases affected by fluctuations. We developed some computer-based procedures, by using the TableCurve3D from Jandel Scientific software and equations Runge-Kutta in MATLAB for taking into account these fluctuations.

  18. Shifting from priming of salicylic acid- to jasmonic acid-regulated defences by Trichoderma protects tomato against the root knot nematode Meloidogyne incognita

    Martínez-Medina, Ainhoa; Fernandez, Ivan; Lok, Gerrit B; Pozo, María J; Pieterse, Corné M J|info:eu-repo/dai/nl/113115113; Van Wees, Saskia C M|info:eu-repo/dai/nl/185445373

    Beneficial root endophytes such as Trichoderma spp. can reduce infections by parasitic nematodes through triggering host defences. Little is currently known about the complex hormone signalling underlying the induction of resistance. In this study, we investigated whether Trichoderma modulates the

  19. Jasmonates induce both defense responses and communication in monocotyledonous and dicotyledonous plants.

    Okada, Kazunori; Abe, Hiroshi; Arimura, Gen-ichiro

    2015-01-01

    Jasmonic acid (JA) and its derivatives (jasmonates, JAs) are phytohormones with essential roles in plant defense against pathogenesis and herbivorous arthropods. Both the up- and down-regulation of defense responses are dependent on signaling pathways mediated by JAs as well as other stress hormones (e.g. salicylic acid), generally those involving the transcriptional and post-transcriptional regulation of transcription factors via protein modification and epigenetic regulation. In addition to the typical model plant Arabidopsis (a dicotyledon), advances in genetics research have made rice a model monocot in which innovative pest control traits can be introduced and whose JA signaling pathway can be studied. In this review, we introduce the dynamic functions of JAs in plant defense strategy using defensive substances (e.g. indole alkaloids and terpenoid phytoalexins) and airborne signals (e.g. green leaf volatiles and volatile terpenes) in response to biotrophic and necrotrophic pathogens as well as above-ground and below-ground herbivores. We then discuss the important issue of how the mutualism of herbivorous arthropods with viruses or bacteria can cause cross-talk between JA and other phytohormones to counter the defense systems. © The Author 2014. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  20. Phospholipase D and phosphatidic acid in plant defence response: from protein–protein and lipid–protein interactions to hormone signalling

    Zhao, Jian

    2015-01-01

    Phospholipase Ds (PLDs) and PLD-derived phosphatidic acids (PAs) play vital roles in plant hormonal and environmental responses and various cellular dynamics. Recent studies have further expanded the functions of PLDs and PAs into plant–microbe interaction. The molecular diversities and redundant functions make PLD–PA an important signalling complex regulating lipid metabolism, cytoskeleton dynamics, vesicle trafficking, and hormonal signalling in plant defence through protein–protein and protein–lipid interactions or hormone signalling. Different PLD–PA signalling complexes and their targets have emerged as fast-growing research topics for understanding their numerous but not yet established roles in modifying pathogen perception, signal transduction, and downstream defence responses. Meanwhile, advanced lipidomics tools have allowed researchers to reveal further the mechanisms of PLD–PA signalling complexes in regulating lipid metabolism and signalling, and their impacts on jasmonic acid/oxylipins, salicylic acid, and other hormone signalling pathways that essentially mediate plant defence responses. This review attempts to summarize the progress made in spatial and temporal PLD/PA signalling as well as PLD/PA-mediated modification of plant defence. It presents an in-depth discussion on the functions and potential mechanisms of PLD–PA complexes in regulating actin filament/microtubule cytoskeleton, vesicle trafficking, and hormonal signalling, and in influencing lipid metabolism-derived metabolites as critical signalling components in plant defence responses. The discussion puts PLD–PA in a broader context in order to guide future research. PMID:25680793

  1. The role of abscisic acid in plant–pathogen interactions

    Mauch-Mani, Brigitte; Mauch, Felix

    2006-01-01

    The effect of the abiotic stress hormone abscisic acid on plant disease resistance is a neglected field of research. With few exceptions, abscisic acid has been considered a negative regulator of disease resistance. This negative effect appears to be due to the interference of abscisic acid with biotic stress signaling that is regulated by salicylic acid, jasmonic acid and ethylene, and to an additional effect of ABA on shared components of stress signaling. However, recent research shows tha...

  2. New roles for cis-jasmone as an insect semiochemical and in plant defense.

    Birkett, M A; Campbell, C A; Chamberlain, K; Guerrieri, E; Hick, A J; Martin, J L; Matthes, M; Napier, J A; Pettersson, J; Pickett, J A; Poppy, G M; Pow, E M; Pye, B J; Smart, L E; Wadhams, G H; Wadhams, L J; Woodcock, C M

    2000-08-01

    cis-jasmone, or (Z)-jasmone, is well known as a component of plant volatiles, and its release can be induced by damage, for example during insect herbivory. Using the olfactory system of the lettuce aphid to investigate volatiles from plants avoided by this insect, (Z)-jasmone was found to be electrophysiologically active and also to be repellent in laboratory choice tests. In field studies, repellency from traps was demonstrated for the damson-hop aphid, and with cereal aphids numbers were reduced in plots of winter wheat treated with (Z)-jasmone. In contrast, attractant activity was found in laboratory and wind tunnel tests for insects acting antagonistically to aphids, namely the seven-spot ladybird and an aphid parasitoid. When applied in the vapor phase to intact bean plants, (Z)-jasmone induced the production of volatile compounds, including the monoterpene (E)-beta-ocimene, which affect plant defense, for example by stimulating the activity of parasitic insects. These plants were more attractive to the aphid parasitoid in the wind tunnel when tested 48 h after exposure to (Z)-jasmone had ceased. This possible signaling role of (Z)-jasmone is qualitatively different from that of the biosynthetically related methyl jasmonate and gives a long-lasting effect after removal of the stimulus. Differential display was used to compare mRNA populations in bean leaves exposed to the vapor of (Z)-jasmone and methyl jasmonate. One differentially displayed fragment was cloned and shown by Northern blotting to be up-regulated in leaf tissue by (Z)-jasmone. This sequence was identified by homology as being derived from a gene encoding an alpha-tubulin isoform.

  3. Overexpression of Poplar PtrWRKY89 in Transgenic Arabidopsis Leads to a Reduction of Disease Resistance by Regulating Defense-Related Genes in Salicylate- and Jasmonate-Dependent Signaling.

    Jiang, Yuanzhong; Guo, Li; Liu, Rui; Jiao, Bo; Zhao, Xin; Ling, Zhengyi; Luo, Keming

    2016-01-01

    The plant hormones jasmonic acid (JA) and salicylic acid (SA) play key roles in plant defenses against pathogens and several WRKY transcription factors have been shown to have a role in SA/JA crosstalk. In a previous study, overexpression of the poplar WRKY gene PtrWRKY89 enhanced resistance to pathogens in transgenic poplars. In this study, the promoter of PtrWRKY89 (ProPtrWRKY89) was isolated and used to drive GUS reporter gene. High GUS activity was observed in old leaves of transgenic Arabidopsis containing ProPtrWRKY89-GUS construct and GUS expression was extremely induced by SA solution and SA+MeJA mixture but not by MeJA treatment. Subcellular localization and transactivation assays showed that PtrWRKY89 acted as a transcription activator in the nucleus. Constitutive expression of PtrWRKY89 in Arabidopsis resulted in more susceptible to Pseudomonas syringae and Botrytis cinerea compared to wild-type plants. Quantitative real-time PCR (qRT-PCR) analysis confirmed that marker genes of SA and JA pathways were down-regulated in transgenic Arabidopsis after pathogen inoculations. Overall, our results indicated that PtrWRKY89 modulates a cross talk in resistance to P. syringe and B. cinerea by negatively regulating both SA and JA pathways in Arabidopsis.

  4. Overexpression of Poplar PtrWRKY89 in Transgenic Arabidopsis Leads to a Reduction of Disease Resistance by Regulating Defense-Related Genes in Salicylate- and Jasmonate-Dependent Signaling.

    Yuanzhong Jiang

    Full Text Available The plant hormones jasmonic acid (JA and salicylic acid (SA play key roles in plant defenses against pathogens and several WRKY transcription factors have been shown to have a role in SA/JA crosstalk. In a previous study, overexpression of the poplar WRKY gene PtrWRKY89 enhanced resistance to pathogens in transgenic poplars. In this study, the promoter of PtrWRKY89 (ProPtrWRKY89 was isolated and used to drive GUS reporter gene. High GUS activity was observed in old leaves of transgenic Arabidopsis containing ProPtrWRKY89-GUS construct and GUS expression was extremely induced by SA solution and SA+MeJA mixture but not by MeJA treatment. Subcellular localization and transactivation assays showed that PtrWRKY89 acted as a transcription activator in the nucleus. Constitutive expression of PtrWRKY89 in Arabidopsis resulted in more susceptible to Pseudomonas syringae and Botrytis cinerea compared to wild-type plants. Quantitative real-time PCR (qRT-PCR analysis confirmed that marker genes of SA and JA pathways were down-regulated in transgenic Arabidopsis after pathogen inoculations. Overall, our results indicated that PtrWRKY89 modulates a cross talk in resistance to P. syringe and B. cinerea by negatively regulating both SA and JA pathways in Arabidopsis.

  5. Abscisic Acid and abiotic stress signaling.

    Tuteja, Narendra

    2007-05-01

    Abiotic stress is severe environmental stress, which impairs crop production on irrigated land worldwide. Overall, the susceptibility or tolerance to the stress in plants is a coordinated action of multiple stress responsive genes, which also cross-talk with other components of stress signal transduction pathways. Plant responses to abiotic stress can be determined by the severity of the stress and by the metabolic status of the plant. Abscisic acid (ABA) is a phytohormone critical for plant growth and development and plays an important role in integrating various stress signals and controlling downstream stress responses. Plants have to adjust ABA levels constantly in responce to changing physiological and environmental conditions. To date, the mechanisms for fine-tuning of ABA levels remain elusive. The mechanisms by which plants respond to stress include both ABA-dependent and ABA-independent processes. Various transcription factors such as DREB2A/2B, AREB1, RD22BP1 and MYC/MYB are known to regulate the ABA-responsive gene expression through interacting with their corrosponding cis-acting elements such as DRE/CRT, ABRE and MYCRS/MYBRS, respectively. Understanding these mechanisms is important to improve stress tolerance in crops plants. This article first describes the general pathway for plant stress response followed by roles of ABA and transcription factors in stress tolerance including the regulation of ABA biosynthesis.

  6. Non-pathogenic rhizobacteria interfere with the attraction of parasitoids to aphid-induced plant volatiles via jasmonic acid signalling.

    Pineda, A.; Soler Gamborena, R.; Weldegergis, B.T.; Shimwela, M.M.; Loon, van J.J.A.; Dicke, M.

    2013-01-01

    Beneficial soil-borne microbes, such as mycorrhizal fungi or rhizobacteria, can affect the interactions of plants with aboveground insects at several trophic levels. While the mechanisms of interactions with herbivorous insects, that is, the second trophic level, are starting to be understood, it

  7. Jasmonate induction of the monoterpene linalool confers resistance to rice bacterial blight and its biosynthesis is regulated by JAZ protein in rice.

    Taniguchi, Shiduku; Hosokawa-Shinonaga, Yumi; Tamaoki, Daisuke; Yamada, Shoko; Akimitsu, Kazuya; Gomi, Kenji

    2014-02-01

    Jasmonic acid (JA) is involved in the regulation of host immunity in plants. Recently, we demonstrated that JA signalling has an important role in resistance to rice bacterial blight caused by Xanthomonas oryzae pv. oryzae (Xoo) in rice. Here, we report that many volatile compounds accumulate in response to exogenous application of JA, including the monoterpene linalool. Expression of linalool synthase was up-regulated by JA. Vapour treatment with linalool induced resistance to Xoo, and transgenic rice plants overexpressing linalool synthase were more resistance to Xoo, presumably due to the up-regulation of defence-related genes in the absence of any treatment. JA-induced accumulation of linalool was regulated by OsJAZ8, a rice jasmonate ZIM-domain protein involving the JA signalling pathway at the transcriptional level, suggesting that linalool plays an important role in JA-induced resistance to Xoo in rice. © 2013 John Wiley & Sons Ltd.

  8. A SNARE-protein has opposing functions in penetration resistance and defence signalling pathways

    Zhang, Ziguo; Feechan, Angela; Pedersen, Carsten

    2007-01-01

    Penetration resistance is often the first line of defence against fungal pathogens. Subsequently induced defences are mediated by the programmed cell death (PCD) reaction pathway and the salicylic acid (SA), jasmonic acid (JA) and ethylene (ET) signalling pathways. We previously demonstrated...

  9. NPR1: the spider in the web of induced resistance signaling pathways

    Pieterse, C.M.J.; Loon, L.C. van

    2004-01-01

    The plant hormones salicylic acid (SA), jasmonic acid (JA), and ethylene (ET) are major players in the regulation of signaling networks that are involved in induced defense responses against pathogens and insects. During the past two years, significant progress has been made in understanding the

  10. Bile Acid Signaling in Liver Metabolism and Diseases

    Tiangang Li

    2012-01-01

    Full Text Available Obesity, diabetes, and metabolic syndromes are increasingly recognized as health concerns worldwide. Overnutrition and insulin resistance are the major causes of diabetic hyperglycemia and hyperlipidemia in humans. Studies in the past decade provide evidence that bile acids are not just biological detergents facilitating gut nutrient absorption, but also important metabolic regulators of glucose and lipid homeostasis. Pharmacological alteration of bile acid metabolism or bile acid signaling pathways such as using bile acid receptor agonists or bile acid binding resins may be a promising therapeutic strategy for the treatment of obesity and diabetes. On the other hand, bile acid signaling is complex, and the molecular mechanisms mediating the bile acid effects are still not completely understood. This paper will summarize recent advances in our understanding of bile acid signaling in regulation of glucose and lipid metabolism, and the potentials of developing novel therapeutic strategies that target bile acid metabolism for the treatment of metabolic disorders.

  11. Identification and characterization of jasmonate transporters

    Lambertz, Sophie Konstanze

    of the stimulus but also in distal tissues. The systemic accumulation has been the focus of many studies, which proposed that jasmonate is transported over long and short distances to induce defense responses. However, our knowledge of jasmonate transporting elements is marginal. In this thesis, two jasmonate...... Spodoptera littoralis and the fungus Botrytis cinerea was tested. Wounding assays indicate that the JEFFs are involved in systemic induction of the defense compounds glucosinolates, which may be caused by a JEFF mediated shift of jasmonate precursors to the biologically active form of jasmonates. Further...

  12. Retinoic acid signaling in axonal regeneration

    Radhika ePuttagunta

    2012-01-01

    Full Text Available Following an acute central nervous system injury, axonal regeneration and functional recovery are extremely limited. This is due to an extrinsic inhibitory growth environment and the lack of intrinsic growth competence. Retinoic acid (RA signaling, essential in developmental dorsoventral patterning and specification of spinal motor neurons, has been shown through its receptor, the transcription factor RA receptor β2 (RARß2, to induce axonal regeneration following spinal cord injury (SCI. Recently, it has been shown that in dorsal root ganglia neurons, cAMP levels were greatly increased by lentiviral RARβ2 expression and contributed to neurite outgrowth. Moreover, RARβ agonists, in cerebellar granule neurons and in the brain in vivo, induced phosphoinositide 3-kinase dependent phosphorylation of AKT that was involved in RARβ-dependent neurite outgrowth. More recently, RA-RARß pathways were shown to directly transcriptionally repress a member of the inhibitory Nogo receptor complex, Lingo-1, under an axonal growth inhibitory environment in vitro as well as following spinal injury in vivo. This perspective focuses on these newly discovered molecular mechanisms and future directions in the field.

  13. Insulin-dependent signaling: regulation by amino acids and energy

    Meijer, A. J.

    2004-01-01

    Recent research has indicated that amino acids stimulate a signal-transduction pathway that is also used by insulin. Moreover, for insulin to exert its anabolic and anticatabolic effects on protein, there is an absolute requirement for amino acids. This signaling pathway becomes inhibited by

  14. Response of tobacco to the Pseudomonas syringae pv. Tomato DC3000 is mainly dependent on salicylic acid signaling pathway.

    Liu, Yang; Wang, Li; Cai, Guohua; Jiang, Shanshan; Sun, Liping; Li, Dequan

    2013-07-01

    Pseudomonas syringae pv. Tomato DC3000 (Pst DC3000) was the first pathogen to be demonstrated to infect Arabidopsis and to cause disease symptoms in the laboratory setting. However, the defense response to Pst DC3000 was unclear in tobacco. In this report, the expression profiles of twelve defense response-related genes were analyzed after treatment with salicylic acid (SA), jasmonic acid (JA), and pathogen Pst DC3000 by qRT-PCR. According to our results, it could be presented that the genes primarily induced by SA were also induced to higher levels after Pst DC3000 infection. SA accumulation could be induced to a higher level than that of JA after Pst DC3000 infection. In addition, SA could result in hypersensitive response (HR), which did not completely depend on accumulation of reactive oxygen species. These results indicated that tobacco mainly depended on SA signaling pathway rather than on JA signaling pathway in response to Pst DC3000. Further study demonstrated that JA could significantly inhibit the accumulation of SA and the generation of the HR induced by Pst DC3000. © 2013 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

  15. Up-regulation of abscisic acid signaling pathway facilitates aphid xylem absorption and osmoregulation under drought stress.

    Guo, Huijuan; Sun, Yucheng; Peng, Xinhong; Wang, Qinyang; Harris, Marvin; Ge, Feng

    2016-02-01

    The activation of the abscisic acid (ABA) signaling pathway reduces water loss from plants challenged by drought stress. The effect of drought-induced ABA signaling on the defense and nutrition allocation of plants is largely unknown. We postulated that these changes can affect herbivorous insects. We studied the effects of drought on different feeding stages of pea aphids in the wild-type A17 of Medicago truncatula and ABA signaling pathway mutant sta-1. We examined the impact of drought on plant water status, induced plant defense signaling via the abscisic acid (ABA), jasmonic acid (JA), and salicylic acid (SA) pathways, and on the host nutritional quality in terms of leaf free amino acid content. During the penetration phase of aphid feeding, drought decreased epidermis/mesophyll resistance but increased mesophyll/phloem resistance of A17 but not sta-1 plants. Quantification of transcripts associated with ABA, JA and SA signaling indicated that the drought-induced up-regulation of ABA signaling decreased the SA-dependent defense but increased the JA-dependent defense in A17 plants. During the phloem-feeding phase, drought had little effect on the amino acid concentrations and the associated aphid phloem-feeding parameters in both plant genotypes. In the xylem absorption stage, drought decreased xylem absorption time of aphids in both genotypes because of decreased water potential. Nevertheless, the activation of the ABA signaling pathway increased water-use efficiency of A17 plants by decreasing the stomatal aperture and transpiration rate. In contrast, the water potential of sta-1 plants (unable to close stomata) was too low to support xylem absorption activity of aphids; the aphids on sta-1 plants had the highest hemolymph osmolarity and lowest abundance under drought conditions. Taken together this study illustrates the significance of cross-talk between biotic-abiotic signaling pathways in plant-aphid interaction, and reveals the mechanisms leading to alter

  16. Maintaining postharvest quality of cold stored 'Hass' avocados by altering the fatty acids content and composition with the use of natural volatile compounds - methyl jasmonate and methyl salicylate.

    Glowacz, Marcin; Bill, Malick; Tinyane, Peter P; Sivakumar, Dharini

    2017-12-01

    Low temperatures are often used to reduce metabolic processes and extend the storage life of fruit; however, in the case of avocado, a temperature below 3 °C will often result in the development of physiological disorders associated with chilling injury. The objective of this study was to investigate the ability of methyl jasmonate (MeJA) and methyl salicylate (MeSA) vapours to alleviate chilling injury in 'Hass' avocado fruit kept at 2 °C for 21 days followed by 6-7 days of shelf-life at 20 °C, simulating supply chain conditions. The incidence and severity of chilling injury were significantly reduced in MeJA- and MeSA-exposed fruit, especially at 100 µmol L -1 . The mechanism involved improved membrane integrity via alteration of the fatty acid content and composition, down-regulation of LOX gene expression and reduced activity of lipoxygenase. MeJA and MeSA have the potential for being used with 'Hass' avocado fruit shipped at low temperature to reduce its susceptibility to chilling injury. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

  17. Phospholipase D and phosphatidic acid in plant defence response: from protein-protein and lipid-protein interactions to hormone signalling.

    Zhao, Jian

    2015-04-01

    Phospholipase Ds (PLDs) and PLD-derived phosphatidic acids (PAs) play vital roles in plant hormonal and environmental responses and various cellular dynamics. Recent studies have further expanded the functions of PLDs and PAs into plant-microbe interaction. The molecular diversities and redundant functions make PLD-PA an important signalling complex regulating lipid metabolism, cytoskeleton dynamics, vesicle trafficking, and hormonal signalling in plant defence through protein-protein and protein-lipid interactions or hormone signalling. Different PLD-PA signalling complexes and their targets have emerged as fast-growing research topics for understanding their numerous but not yet established roles in modifying pathogen perception, signal transduction, and downstream defence responses. Meanwhile, advanced lipidomics tools have allowed researchers to reveal further the mechanisms of PLD-PA signalling complexes in regulating lipid metabolism and signalling, and their impacts on jasmonic acid/oxylipins, salicylic acid, and other hormone signalling pathways that essentially mediate plant defence responses. This review attempts to summarize the progress made in spatial and temporal PLD/PA signalling as well as PLD/PA-mediated modification of plant defence. It presents an in-depth discussion on the functions and potential mechanisms of PLD-PA complexes in regulating actin filament/microtubule cytoskeleton, vesicle trafficking, and hormonal signalling, and in influencing lipid metabolism-derived metabolites as critical signalling components in plant defence responses. The discussion puts PLD-PA in a broader context in order to guide future research. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  18. Cauliflower mosaic virus protein P6 inhibits signaling responses to salicylic acid and regulates innate immunity.

    Andrew J Love

    Full Text Available Cauliflower mosaic virus (CaMV encodes a multifunctional protein P6 that is required for translation of the 35S RNA and also acts as a suppressor of RNA silencing. Here we demonstrate that P6 additionally acts as a pathogenicity effector of an unique and novel type, modifying NPR1 (a key regulator of salicylic acid (SA- and jasmonic acid (JA-dependent signaling and inhibiting SA-dependent defence responses We find that that transgene-mediated expression of P6 in Arabidopsis and transient expression in Nicotiana benthamiana has profound effects on defence signaling, suppressing expression of representative SA-responsive genes and increasing expression of representative JA-responsive genes. Relative to wild-type Arabidopsis P6-expressing transgenics had greatly reduced expression of PR-1 following SA-treatment, infection by CaMV or inoculation with an avirulent bacterial pathogen Pseudomonas syringae pv tomato (Pst. Similarly transient expression in Nicotiana benthamiana of P6 (including a mutant form defective in translational transactivation activity suppressed PR-1a transcript accumulation in response to Agrobacterium infiltration and following SA-treatment. As well as suppressing the expression of representative SA-regulated genes, P6-transgenic Arabidopsis showed greatly enhanced susceptibility to both virulent and avirulent Pst (titres elevated 10 to 30-fold compared to non-transgenic controls but reduced susceptibility to the necrotrophic fungus Botrytis cinerea. Necrosis following SA-treatment or inoculation with avirulent Pst was reduced and delayed in P6-transgenics. NPR1 an important regulator of SA/JA crosstalk, was more highly expressed in the presence of P6 and introduction of the P6 transgene into a transgenic line expressing an NPR1:GFP fusion resulted in greatly increased fluorescence in nuclei even in the absence of SA. Thus in the presence of P6 an inactive form of NPR1 is mislocalized in the nucleus even in uninduced plants

  19. Magical mystery tour: Salicylic acid signalling

    Janda, Martin; Ruelland, E.

    2015-01-01

    Roč. 114, Special Issue (2015), s. 117-128 ISSN 0098-8472 R&D Projects: GA ČR(CZ) GAP501/11/1654 Institutional support: RVO:61389030 Keywords : Salicylic acid (SA) * NPR1 * SA overaccumulating mutants Subject RIV: ED - Physiology Impact factor: 3.712, year: 2015

  20. Differential expression of jasmonate biosynthesis genes in cacao genotypes contrasting for resistance against Moniliophthora perniciosa.

    Litholdo, Celso G; Leal, Gildemberg A; Albuquerque, Paulo S B; Figueira, Antonio

    2015-10-01

    The resistance mechanism of cacao against M. perniciosa is likely to be mediated by JA/ET-signaling pathways due to the preferential TcAOS and TcSAM induction in a resistant genotype. The basidiomycete Moniliophthora perniciosa causes a serious disease in cacao (Theobroma cacao L.), and the use of resistant varieties is the only sustainable long-term solution. Cacao resistance against M. perniciosa is characterized by pathogen growth inhibition with reduced colonization and an attenuation of disease symptoms, suggesting a regulation by jasmonate (JA)/ethylene (ET) signaling pathways. The hypothesis that genes involved in JA biosynthesis would be active in the interaction of T. cacao and M. perniciosa was tested here. The cacao JA-related genes were evaluated for their relative quantitative expression in susceptible and resistant genotypes upon the exogenous application of ET, methyl-jasmonate (MJ), and salicylic acid (SA), or after M. perniciosa inoculation. MJ treatment triggered changes in the expression of genes involved in JA biosynthesis, indicating that the mechanism of positive regulation by exogenous MJ application occurs in cacao. However, a higher induction of these genes was observed in the susceptible genotype. Further, a contrast in JA-related transcriptional expression was detected between susceptible and resistant plants under M. perniciosa infection, with the induction of the allene oxide synthase gene (TcAOS), which encodes a key enzyme in the JA biosynthesis pathway in the resistant genotype. Altogether, this work provides additional evidences that the JA-dependent signaling pathway is modulating the defense response against M. perniciosa in a cacao-resistant genotype.

  1. The WRKY57 Transcription Factor Affects the Expression of Jasmonate ZIM-Domain Genes Transcriptionally to Compromise Botrytis cinerea Resistance.

    Jiang, Yanjuan; Yu, Diqiu

    2016-08-01

    Although necrotrophic pathogens cause many devastating plant diseases, our understanding of the plant defense response to them is limited. Here, we found that loss of function of WRKY57 enhanced the resistance of Arabidopsis (Arabidopsis thaliana) against Botrytis cinerea infection. Further investigation suggested that the negative regulation of WRKY57 against B cinerea depends on the jasmonic acid (JA) signaling pathway. Chromatin immunoprecipitation experiments revealed that WRKY57 directly binds to the promoters of JASMONATE ZIM-DOMAIN1 (JAZ1) and JAZ5, encoding two important repressors of the JA signaling pathway, and activates their transcription. In vivo and in vitro experiments demonstrated that WRKY57 interacts with nuclear-encoded SIGMA FACTOR BINDING PROTEIN1 (SIB1) and SIB2. Further experiments display that the same domain, the VQ motif, of SIB1 and SIB2 interact with WRKY33 and WRKY57. Moreover, transient transcriptional activity assays confirmed that WRKY57 and WRKY33 competitively regulate JAZ1 and JAZ5, SIB1 and SIB2 further enhance these competitions of WRKY57 to WRKY33. Therefore, coordinated regulation of Arabidopsis against B cinerea by transcription activators and repressors would benefit plants by allowing fine regulation of defense. © 2016 American Society of Plant Biologists. All Rights Reserved.

  2. Retinoic Acid Signaling in Thymic Epithelial Cells Regulates Thymopoiesis

    Wendland, Kerstin; Niss, Kristoffer; Kotarsky, Knut

    2018-01-01

    Despite the essential role of thymic epithelial cells (TEC) in T cell development, the signals regulating TEC differentiation and homeostasis remain incompletely understood. In this study, we show a key in vivo role for the vitamin A metabolite, retinoic acid (RA), in TEC homeostasis. In the abse......Despite the essential role of thymic epithelial cells (TEC) in T cell development, the signals regulating TEC differentiation and homeostasis remain incompletely understood. In this study, we show a key in vivo role for the vitamin A metabolite, retinoic acid (RA), in TEC homeostasis...

  3. Bile acid metabolism and signaling in cholestasis, inflammation and cancer

    Apte, Udayan

    2015-01-01

    Bile acids are synthesized from cholesterol in the liver. Some cytochrome P450 (CYP) enzymes play key roles in bile acid synthesis. Bile acids are physiological detergent molecules, so are highly cytotoxic. They undergo enterohepatic circulation and play important roles in generating bile flow and facilitating biliary secretion of endogenous metabolites and xenobiotics and intestinal absorption of dietary fats and lipid soluble vitamins. Bile acid synthesis, transport and pool size are therefore tightly regulated under physiological conditions. In cholestasis, impaired bile flow leads to accumulation of bile acids in the liver, causing hepatocyte and biliary injury and inflammation. Chronic cholestasis is associated with fibrosis, cirrhosis and eventually liver failure. Chronic cholestasis also increases the risk of developing hepatocellular or cholangiocellular carcinomas. Extensive research in the last two decades has shown that bile acids act as signaling molecules that regulate various cellular processes. The bile acid-activated nuclear receptors are ligand-activated transcriptional factors that play critical roles in the regulation of bile acid, drug and xenobiotic metabolism. In cholestasis, these bile acid-activated receptors regulate a network of genes involved in bile acid synthesis, conjugation, transport and metabolism to alleviate bile acid-induced inflammation and injury. Additionally, bile acids are known to regulate cell growth and proliferation, and altered bile acid levels in diseased conditions have been implicated in liver injury/regeneration and tumorigenesis. We will cover the mechanisms that regulate bile acid homeostasis and detoxification during cholestasis, and the roles of bile acids in the initiation and regulation of hepatic inflammation, regeneration and carcinogenesis. PMID:26233910

  4. Characterisation of an Arabidopsis-Leptosphaeria maculans pathosystem: resistance partially requires camalexin biosynthesis and is independent of salicylic acid, ethylene and jasmonic acid signalling

    Bohman, S.; Staal, J.; Thomma, B.P.H.J.; Wang, M.; Dixelius, C.

    2004-01-01

    Out of 168 Arabidopsis accessions screened with isolates of Leptosphaeria maculans, one (An-1) showed clear disease symptoms. In order to identify additional components involved in containment of L. maculans in Arabidopsis, a screen for L. maculans-susceptible (lms) mutants was performed. Eleven lms

  5. Functions and Signaling Pathways of Amino Acids in Intestinal Inflammation

    Fang He

    2018-01-01

    Full Text Available Intestine is always exposed to external environment and intestinal microorganism; thus it is more sensitive to dysfunction and dysbiosis, leading to intestinal inflammation, such as inflammatory bowel disease (IBD, irritable bowel syndrome (IBS, and diarrhea. An increasing number of studies indicate that dietary amino acids play significant roles in preventing and treating intestinal inflammation. The review aims to summarize the functions and signaling mechanisms of amino acids in intestinal inflammation. Amino acids, including essential amino acids (EAAs, conditionally essential amino acids (CEAAs, and nonessential amino acids (NEAAs, improve the functions of intestinal barrier and expressions of anti-inflammatory cytokines and tight junction proteins but decrease oxidative stress and the apoptosis of enterocytes as well as the expressions of proinflammatory cytokines in the intestinal inflammation. The functions of amino acids are associated with various signaling pathways, including mechanistic target of rapamycin (mTOR, inducible nitric oxide synthase (iNOS, calcium-sensing receptor (CaSR, nuclear factor-kappa-B (NF-κB, mitogen-activated protein kinase (MAPK, nuclear erythroid-related factor 2 (Nrf2, general controlled nonrepressed kinase 2 (GCN2, and angiotensin-converting enzyme 2 (ACE2.

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

    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),

  7. Phosphatidic acid: a multifunctional stress-signalling lipid in plants.

    Testerink, C.; Munnik, T.

    2005-01-01

    Phosphatidic acid (PA) has only recently been identified as an important signaling molecule in both plants and animals. Nonetheless, it already promises to rival the importance of the classic second messengers Ca(2+) and cAMP. In plants, its formation is triggered in response to various biotic and

  8. The ins and outs of lysophosphatidic acid signaling

    Moolenaar, Wouter H; van Meeteren, Laurens A; Giepmans, Ben N G

    Lysophosphatidic acid (LPA) is a lipid mediator with a wide variety of biological actions, particularly as an inducer of cell proliferation, migration and survival. LPA binds to specific G-protein-coupled receptors and thereby activates multiple signal transduction pathways, including those

  9. Apoptosis and signalling in acid sphingomyelinase deficient cells

    Sillence Dan J

    2001-11-01

    Full Text Available Abstract Background Recent evidence suggests that the activation of a non-specific lipid scramblase during apoptosis induces the flipping of sphingomyelin from the cell surface to the cytoplasmic leaftet of the plasma membrane. Inner leaflet sphingomyelin is then cleaved to ceramide by a neutral sphingomyelinase. The production of this non-membrane forming lipid induces blebbing of the plasma membrane to aid rapid engulfment by professional phagocytes. However contrary evidence suggests that cells which are deficient in acid sphingomyelinase are defective in apoptosis signalling. This data has been interpreted as support for the activation of acid sphingomyelinase as an early signal in apoptosis. Hypothesis An alternative explanation is put forward whereby the accumulation of intracellular sphingomyelin in sphingomyelinase deficient cells leads to the formation of intracellular rafts which lead to the sequestration of important signalling molecules that are normally present on the cell surface where they perform their function. Testing the hypothesis It is expected that the subcellular distribution of important signalling molecules is altered in acid sphingomyelinase deficient cells, leading to their sequestration in late endosomes / lysosomes. Other sphingolipid storage diseases such as Niemann-Pick type C which have normal acid sphingomyelinase activity would also be expected to show the same phenotype. Implications of the hypothesis If true the hypothesis would provide a mechanism for the pathology of the sphingolipid storage diseases at the cellular level and also have implications for the role of ceramide in apoptosis.

  10. Bile Acid Signaling in Metabolic Disease and Drug Therapy

    Li, Tiangang

    2014-01-01

    Bile acids are the end products of cholesterol catabolism. Hepatic bile acid synthesis accounts for a major fraction of daily cholesterol turnover in humans. Biliary secretion of bile acids generates bile flow and facilitates hepatobiliary secretion of lipids, lipophilic metabolites, and xenobiotics. In the intestine, bile acids are essential for the absorption, transport, and metabolism of dietary fats and lipid-soluble vitamins. Extensive research in the last 2 decades has unveiled new functions of bile acids as signaling molecules and metabolic integrators. The bile acid–activated nuclear receptors farnesoid X receptor, pregnane X receptor, constitutive androstane receptor, vitamin D receptor, and G protein–coupled bile acid receptor play critical roles in the regulation of lipid, glucose, and energy metabolism, inflammation, and drug metabolism and detoxification. Bile acid synthesis exhibits a strong diurnal rhythm, which is entrained by fasting and refeeding as well as nutrient status and plays an important role for maintaining metabolic homeostasis. Recent research revealed an interaction of liver bile acids and gut microbiota in the regulation of liver metabolism. Circadian disturbance and altered gut microbiota contribute to the pathogenesis of liver diseases, inflammatory bowel diseases, nonalcoholic fatty liver disease, diabetes, and obesity. Bile acids and their derivatives are potential therapeutic agents for treating metabolic diseases of the liver. PMID:25073467

  11. Differential impact of lipoxygenase 2 and jasmonates on natural and stress-induced senescence in Arabidopsis.

    Seltmann, Martin A; Stingl, Nadja E; Lautenschlaeger, Jens K; Krischke, Markus; Mueller, Martin J; Berger, Susanne

    2010-04-01

    Jasmonic acid and related oxylipins are controversially discussed to be involved in regulating the initiation and progression of leaf senescence. To this end, we analyzed profiles of free and esterified oxylipins during natural senescence and upon induction of senescence-like phenotypes by dark treatment and flotation on sorbitol in Arabidopsis (Arabidopsis thaliana). Jasmonic acid and free 12-oxo-phytodienoic acid increased during all three processes, with the strongest increase of jasmonic acid after dark treatment. Arabidopside content only increased considerably in response to sorbitol treatment. Monogalactosyldiacylglycerols and digalactosyldiacylglycerols decreased during these treatments and aging. Lipoxygenase 2-RNA interference (RNAi) plants were generated, which constitutively produce jasmonic acid and 12-oxo-phytodienoic acid but do not exhibit accumulation during natural senescence or upon stress treatment. Chlorophyll loss during aging and upon dark incubation was not altered, suggesting that these oxylipins are not involved in these processes. In contrast, lipoxygenase 2-RNAi lines and the allene oxid synthase-deficient mutant dde2 were less sensitive to sorbitol than the wild type, indicating that oxylipins contribute to the response to sorbitol stress.

  12. Manipulating the jasmonate response: How do methyl jasmonate additions mediate characteristics of aboveground and belowground mutualisms?

    Kiers, E.T.; Adler, L.S.; Grman, E.L.; van der Heijden, M.G.A.

    2010-01-01

    Plants use a range of sophisticated strategies to protect themselves against herbivores and pathogens, such as the production of jasmonates, a group of plant hormones that prime the plant's defense system upon attack. However, defense-related mechanisms, such as the jasmonate response, play a more

  13. Verticillium dahliae-Arabidopsis Interaction Causes Changes in Gene Expression Profiles and Jasmonate Levels on Different Time Scales

    Sandra S. Scholz

    2018-02-01

    Full Text Available Verticillium dahliae is a soil-borne vascular pathogen that causes severe wilt symptoms in a wide range of plants. Co-culture of the fungus with Arabidopsis roots for 24 h induces many changes in the gene expression profiles of both partners, even before defense-related phytohormone levels are induced in the plant. Both partners reprogram sugar and amino acid metabolism, activate genes for signal perception and transduction, and induce defense- and stress-responsive genes. Furthermore, analysis of Arabidopsis expression profiles suggests a redirection from growth to defense. After 3 weeks, severe disease symptoms can be detected for wild-type plants while mutants impaired in jasmonate synthesis and perception perform much better. Thus, plant jasmonates have an important influence on the interaction, which is already visible at the mRNA level before hormone changes occur. The plant and fungal genes that rapidly respond to the presence of the partner might be crucial for early recognition steps and the future development of the interaction. Thus they are potential targets for the control of V. dahliae-induced wilt diseases.

  14. More JAZ in the orchestration of jasmonate-mediated plant defense

    Zhou, Meiliang

    2014-01-01

    Jasmonates (JAs) are plant hormones that regulate defense against microbial pathogens and insect herbivores via two antagonistic branches of the JAs signaling pathway leading to activation of distinct sets of defense genes. In Arabidopsis thaliana defense against herbivores is regulated by JAs alone

  15. Jasmonate-deficient plants have reduced direct and indirect defences against herbivores

    Thaler, J.S.; Farag, M.A.; Paré, P.W.; Dicke, M.

    2002-01-01

    Plants employ a variety of defence mechanisms, some of which act directly by having a negative effect on herbivores and others that act indirectly by attracting natural enemies of herbivores. In this study we asked if a common jasmonate-signalling pathway links the regulation of direct and indirect

  16. Priming of jasmonate-mediated anti-herbivore defense responses in rice by silicon

    While the function of silicon (Si) in plant physiology has long been debated, its beneficial effects on plant resistance against abiotic and biotic stresses, ¬including insect herbivory, have been well-documented. In addition, the jasmonate (JA) signaling pathway plays a crucial role in mediating an...

  17. Bioassays for assessing jasmonate-dependent defenses triggered by pathogens, herbivorous Insects, or beneficial rhizobacteria

    Van Wees, S.C.M. van; Van Pelt, J.A. van; Bakker, P.A.H.M.; Pieterse, C.M.J.

    2013-01-01

    Jasmonates, together with other plant hormones, are important orchestrators of the plant immune system. The different hormone-controlled signaling pathways cross-communicate in an antagonistic or a synergistic manner, providing the plant with a powerful capacity to fi nely regulate its immune

  18. The jasmonate receptor COI1 plays a role in jasmonate-induced lateral root formation and lateral root positioning in Arabidopsis thaliana.

    Raya-González, Javier; Pelagio-Flores, Ramón; López-Bucio, José

    2012-09-15

    Jasmonic acid (JA) regulates a broad range of plant defense and developmental responses. COI1 has been recently found to act as JA receptor. In this report, we show that low micromolar concentrations of JA inhibited primary root (PR) growth and promoted lateral root (LR) formation in Arabidopsis wild-type (WT) seedlings. It was observed that the coi1-1 mutant was less sensitive to JA on pericycle cell activation to induce lateral root primordia (LRP) formation and presented alterations in lateral root positioning and lateral root emergence on bends. To investigate JA-auxin interactions important for remodeling of root system (RS) architecture, we tested the expression of auxin-inducible markers DR5:uidA and BA3:uidA in WT and coi1-1 seedlings in response to indole-3-acetic acid (IAA) and JA and analyzed the RS architecture of a suite of auxin-related mutants under JA treatments. We found that JA did not affect DR5:uidA and BA3:uidA expression in WT and coi1-1 seedlings. Our data also showed that PR growth inhibition in response to JA was likely independent of auxin signaling and that the induction of LRP required ARF7, ARF19, SLR, TIR1, AFB2, AFB3 and AXR1 loci. We conclude that JA regulation of postembryonic root development involves both auxin-dependent and independent mechanisms. Copyright © 2012 Elsevier GmbH. All rights reserved.

  19. Stress Marker Signatures in Lesion Mimic Single and Double Mutants Identify a Crucial Leaf Age-Dependent Salicylic Acid Related Defense Signal.

    Kaurilind, Eve; Brosché, Mikael

    2017-01-01

    Plants are exposed to abiotic and biotic stress conditions throughout their lifespans that activates various defense programs. Programmed cell death (PCD) is an extreme defense strategy the plant uses to manage unfavorable environments as well as during developmentally induced senescence. Here we investigated the role of leaf age on the regulation of defense gene expression in Arabidopsis thaliana. Two lesion mimic mutants with misregulated cell death, catalase2 (cat2) and defense no death1 (dnd1) were used together with several double mutants to dissect signaling pathways regulating defense gene expression associated with cell death and leaf age. PCD marker genes showed leaf age dependent expression, with the highest expression in old leaves. The salicylic acid (SA) biosynthesis mutant salicylic acid induction deficient2 (sid2) had reduced expression of PCD marker genes in the cat2 sid2 double mutant demonstrating the importance of SA biosynthesis in regulation of defense gene expression. While the auxin- and jasmonic acid (JA)- insensitive auxin resistant1 (axr1) double mutant cat2 axr1 also led to decreased expression of PCD markers; the expression of several marker genes for SA signaling (ISOCHORISMATE SYNTHASE 1, PR1 and PR2) were additionally decreased in cat2 axr1 compared to cat2. The reduced expression of these SA markers genes in cat2 axr1 implicates AXR1 as a regulator of SA signaling in addition to its known role in auxin and JA signaling. Overall, the current study reinforces the important role of SA signaling in regulation of leaf age-related transcript signatures.

  20. Suppressed hepatic bile acid signalling despite elevated production of primary and secondary bile acids in NAFLD.

    Jiao, Na; Baker, Susan S; Chapa-Rodriguez, Adrian; Liu, Wensheng; Nugent, Colleen A; Tsompana, Maria; Mastrandrea, Lucy; Buck, Michael J; Baker, Robert D; Genco, Robert J; Zhu, Ruixin; Zhu, Lixin

    2017-08-03

    Bile acids are regulators of lipid and glucose metabolism, and modulate inflammation in the liver and other tissues. Primary bile acids such as cholic acid and chenodeoxycholic acid (CDCA) are produced in the liver, and converted into secondary bile acids such as deoxycholic acid (DCA) and lithocholic acid by gut microbiota. Here we investigated the possible roles of bile acids in non-alcoholic fatty liver disease (NAFLD) pathogenesis and the impact of the gut microbiome on bile acid signalling in NAFLD. Serum bile acid levels and fibroblast growth factor 19 (FGF19), liver gene expression profiles and gut microbiome compositions were determined in patients with NAFLD, high-fat diet-fed rats and their controls. Serum concentrations of primary and secondary bile acids were increased in patients with NAFLD. In per cent, the farnesoid X receptor (FXR) antagonistic DCA was increased, while the agonistic CDCA was decreased in NAFLD. Increased mRNA expression for cytochrome P450 7A1, Na + -taurocholate cotransporting polypeptide and paraoxonase 1, no change in mRNA expression for small heterodimer partner and bile salt export pump, and reduced serum FGF19 were evidence of impaired FXR and fibroblast growth factor receptor 4 (FGFR4)-mediated signalling in NAFLD. Taurine and glycine metabolising bacteria were increased in the gut of patients with NAFLD, reflecting increased secondary bile acid production. Similar changes in liver gene expression and the gut microbiome were observed in high-fat diet-fed rats. The serum bile acid profile, the hepatic gene expression pattern and the gut microbiome composition consistently support an elevated bile acid production in NAFLD. The increased proportion of FXR antagonistic bile acid explains, at least in part, the suppression of hepatic FXR-mediated and FGFR4-mediated signalling. Our study suggests that future NAFLD intervention may target the components of FXR signalling, including the bile acid converting gut microbiome. © Article

  1. γ-Aminobutyric acid (GABA) signalling in plants.

    Ramesh, Sunita A; Tyerman, Stephen D; Gilliham, Matthew; Xu, Bo

    2017-05-01

    The role of γ-aminobutyric acid (GABA) as a signal in animals has been documented for over 60 years. In contrast, evidence that GABA is a signal in plants has only emerged in the last 15 years, and it was not until last year that a mechanism by which this could occur was identified-a plant 'GABA receptor' that inhibits anion passage through the aluminium-activated malate transporter family of proteins (ALMTs). ALMTs are multigenic, expressed in different organs and present on different membranes. We propose GABA regulation of ALMT activity could function as a signal that modulates plant growth, development, and stress response. In this review, we compare and contrast the plant 'GABA receptor' with mammalian GABA A receptors in terms of their molecular identity, predicted topology, mode of action, and signalling roles. We also explore the implications of the discovery that GABA modulates anion flux in plants, its role in signal transduction for the regulation of plant physiology, and predict the possibility that there are other GABA interaction sites in the N termini of ALMT proteins through in silico evolutionary coupling analysis; we also explore the potential interactions between GABA and other signalling molecules.

  2. Ethylene independent induction of lycopene biosynthesis in tomato fruits by jasmonates

    Wei, Jia; Wang, Qiaomei

    2012-01-01

    One of the main characteristics of tomato (Solanum lycopersicum) fruit ripening is a massive accumulation of carotenoids (mainly lycopene), which may contribute to the nutrient quality of tomato fruit and its role in chemoprevention. Previous studies have shown that ethylene (ET) plays a central role in promoting fruit ripening. In this study, the role of jasmonic acid (JA) in controlling lycopene accumulation in tomato fruits was analysed by measuring fruit lycopene content and the expression levels of lycopene biosynthetic genes in JA-deficient mutants (spr2 and def1) and a 35S::prosystemin transgenic line (35S::prosys) with increased JA levels and constitutive JA signalling. The lycopene content was significantly decreased in the fruits of spr2 and def1, but was enhanced in 35S::prosys fruits. Simultaneously, the expression of lycopene biosynthetic genes followed a similar trend. Lycopene synthesis in methyl jasmonate (MeJA) vapour-treated fruits showed an inverted U-shaped dose response, which significantly enhanced the fruit lycopene content and restored lycopene accumulation in spr2 and def1 at a concentration of 0.5 µM. The results indicated that JA plays a positive role in lycopene biosynthesis. In addition, the role of ET in JA-induced lycopene accumulation was also examined. Ethylene production in tomato fruits was depressed in spr2 and def1 while it increased in 35S::prosys. However, the exogenous application of MeJA to Never ripe (Nr), the ET-insensitive mutant, significantly promoted lycopene accumulation, as well as the expression of lycopene biosynthetic genes. Based on these results, it is proposed that JA might function independently of ethylene to promote lycopene biosynthesis in tomato fruits. PMID:22945939

  3. Effects of pre-harvest methyl jasmonate treatment on post-harvest ...

    ... quality and bioactive compounds of three different Japanese plums under storage conditions. Materials and Methods: The effects of pre-harvest methyl jasmonate treatment (MeJA) on weight loss, color characteristics (L*, C* and h°), firmness, soluble solids content (SSC), titratable acidity (TA), total phenolics (TP) and total ...

  4. Lysophosphatidic Acid (LPA Signaling in Human and Ruminant Reproductive Tract

    Izabela Wocławek-Potocka

    2014-01-01

    Full Text Available Lysophosphatidic acid (LPA through activating its G protein-coupled receptors (LPAR 1–6 exerts diverse cellular effects that in turn influence several physiological processes including reproductive function of the female. Studies in various species of animals and also in humans have identified important roles for the receptor-mediated LPA signaling in multiple aspects of human and animal reproductive tract function. These aspects range from ovarian and uterine function, estrous cycle regulation, early embryo development, embryo implantation, decidualization to pregnancy maintenance and parturition. LPA signaling can also have pathological consequences, influencing aspects of endometriosis and reproductive tissue associated tumors. The review describes recent progress in LPA signaling research relevant to human and ruminant reproduction, pointing at the cow as a relevant model to study LPA influence on the human reproductive performance.

  5. Fatty Acid Signaling: The New Function of Intracellular Lipases

    Zuzana Papackova

    2015-02-01

    Full Text Available Until recently, intracellular triacylglycerols (TAG stored in the form of cytoplasmic lipid droplets have been considered to be only passive “energy conserves”. Nevertheless, degradation of TAG gives rise to a pleiotropic spectrum of bioactive intermediates, which may function as potent co-factors of transcription factors or enzymes and contribute to the regulation of numerous cellular processes. From this point of view, the process of lipolysis not only provides energy-rich equivalents but also acquires a new regulatory function. In this review, we will concentrate on the role that fatty acids liberated from intracellular TAG stores play as signaling molecules. The first part provides an overview of the transcription factors, which are regulated by fatty acids derived from intracellular stores. The second part is devoted to the role of fatty acid signaling in different organs/tissues. The specific contribution of free fatty acids released by particular lipases, hormone-sensitive lipase, adipose triacylglycerol lipase and lysosomal lipase will also be discussed.

  6. Rhamnolipids elicit defense responses and induce disease resistance against biotrophic, hemibiotrophic, and necrotrophic pathogens that require different signaling pathways in Arabidopsis and highlight a central role for salicylic acid.

    Sanchez, Lisa; Courteaux, Barbara; Hubert, Jane; Kauffmann, Serge; Renault, Jean-Hugues; Clément, Christophe; Baillieul, Fabienne; Dorey, Stéphan

    2012-11-01

    Plant resistance to phytopathogenic microorganisms mainly relies on the activation of an innate immune response usually launched after recognition by the plant cells of microbe-associated molecular patterns. The plant hormones, salicylic acid (SA), jasmonic acid, and ethylene have emerged as key players in the signaling networks involved in plant immunity. Rhamnolipids (RLs) are glycolipids produced by bacteria and are involved in surface motility and biofilm development. Here we report that RLs trigger an immune response in Arabidopsis (Arabidopsis thaliana) characterized by signaling molecules accumulation and defense gene activation. This immune response participates to resistance against the hemibiotrophic bacterium Pseudomonas syringae pv tomato, the biotrophic oomycete Hyaloperonospora arabidopsidis, and the necrotrophic fungus Botrytis cinerea. We show that RL-mediated resistance involves different signaling pathways that depend on the type of pathogen. Ethylene is involved in RL-induced resistance to H. arabidopsidis and to P. syringae pv tomato whereas jasmonic acid is essential for the resistance to B. cinerea. SA participates to the restriction of all pathogens. We also show evidence that SA-dependent plant defenses are potentiated by RLs following challenge by B. cinerea or P. syringae pv tomato. These results highlight a central role for SA in RL-mediated resistance. In addition to the activation of plant defense responses, antimicrobial properties of RLs are thought to participate in the protection against the fungus and the oomycete. Our data highlight the intricate mechanisms involved in plant protection triggered by a new type of molecule that can be perceived by plant cells and that can also act directly onto pathogens.

  7. Calcium specificity signaling mechanisms in abscisic acid signal transduction in Arabidopsis guard cells

    Brandt, Benjamin; Munemasa, Shintaro; Wang, Cun; Nguyen, Desiree; Yong, Taiming; Yang, Paul G; Poretsky, Elly; Belknap, Thomas F; Waadt, Rainer; Alemán, Fernando; Schroeder, Julian I

    2015-01-01

    A central question is how specificity in cellular responses to the eukaryotic second messenger Ca2+ is achieved. Plant guard cells, that form stomatal pores for gas exchange, provide a powerful system for in depth investigation of Ca2+-signaling specificity in plants. In intact guard cells, abscisic acid (ABA) enhances (primes) the Ca2+-sensitivity of downstream signaling events that result in activation of S-type anion channels during stomatal closure, providing a specificity mechanism in Ca2+-signaling. However, the underlying genetic and biochemical mechanisms remain unknown. Here we show impairment of ABA signal transduction in stomata of calcium-dependent protein kinase quadruple mutant plants. Interestingly, protein phosphatase 2Cs prevent non-specific Ca2+-signaling. Moreover, we demonstrate an unexpected interdependence of the Ca2+-dependent and Ca2+-independent ABA-signaling branches and the in planta requirement of simultaneous phosphorylation at two key phosphorylation sites in SLAC1. We identify novel mechanisms ensuring specificity and robustness within stomatal Ca2+-signaling on a cellular, genetic, and biochemical level. DOI: http://dx.doi.org/10.7554/eLife.03599.001 PMID:26192964

  8. Friends or foes: new insights in jasmonate and ethylene co-actions.

    Zhu, Ziqiang; Lee, Benjamin

    2015-03-01

    One strategy for sessile plants to adapt to their surrounding environment involves the modulation of their various internal phytohormone signaling and distributions when the plants sense environmental change. There are currently dozens of identified phytohormones in plant cells and they act in concert to regulate plant growth, development, metabolism and defense. It has been determined that phytohormones often act together to achieve certain physiological functions. Thus, the study of hormone-hormone interactions is becoming a competitive research field for deciphering the underlying regulatory mechanisms. Among phytohormones, jasmonate and ethylene present a fascinating case of synergism and antagonism. They are commonly recognized as defense hormones that act synergistically. Plants impaired in jasmonate and/or ethylene signaling are susceptible to infections by necrotrophic fungi, suggesting that these two hormones are both required for defense. Moreover, jasmonate and ethylene also act antagonistically, such as in the regulation of apical hook development and wounding responses. Here, we highlight the recent breakthroughs in the understanding of jasmonate-ethylene co-actions and point out the potential power of studying protein-protein interactions for systematically exploring signal cross-talk. © The Author 2014. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  9. Methyl Jasmonate-Induced Lipidomic and Biochemical Alterations in the Intertidal Macroalga Gracilaria dura (Gracilariaceae, Rhodophyta).

    Kumari, Puja; Reddy, C R K; Jha, Bhavanath

    2015-10-01

    The role of exogenously added methyl jasmonate (MeJA), a lipid-derived signaling compound, in inducing oxidative stress in the marine red macroalga Gracilaria dura was investigated. MeJA at a concentration of 1-100 µM was a strong stimulant of reactive oxygen species (H(2)O(2), HO· and O(2) (·-)) (P < 0.05) causing considerable oxidative stress in G. dura. This further led to lipid peroxidation and degradation of the pigments Chl a and phycocyanin, with a concomitant increase in phycoerythrin. The MeJA-induced oxidative burst also led to the induction of a fatty acid oxidation cascade, resulting in the synthesis of hydroxy-oxylipins and the up-regulation of the 13-lipoxygenase pathway. Electrospray ionization-mass spectrometry-based shotgun lipidomic analysis revealed that monogalactosyldiacylglycerol (a chloroplastic glycerolipid) and phosphatidylcholine (extrachloroplastidic phopholipid) were the most affected lipid classes. The degradation of 18:3-fatty acid-containing monogalactosyldiacylglycerol inferred that it provided fatty acyl chains for the biosynthesis of 13-hydroperoxylinolenic acid, which was further directed towards either the jasmonate pathway or other alternative pathways of the fatty acid oxidation cascade, analogous to higher plants. Also, G. dura modulated the lipid acyl chains in such a way that no significant change was observed in the fatty acid profile of the treated thalli as compared with those of the control, except for C16:0, C16:1 (n-9), C20:3 (n-6) and C20:4 (n-6) (P < 0.05). Furthermore, MeJA caused the accumulation of phenolic compounds and the up-regulation of enzymes involved in secondary metabolism such as polyphenol oxidase, shikimate dehydrogenase and phenylalanine ammonia-lyase, indicating a shift towards secondary metabolism as a defense strategy to combat the induced oxidative stress. © The Author 2015. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For

  10. Signal Transducer and Activator of Transcription 3 (STAT3) Mediates Amino Acid Inhibition of Insulin Signaling through Serine 727 Phosphorylation*

    Kim, Jeong-Ho; Yoon, Mee-Sup; Chen, Jie

    2009-01-01

    Nutrient overload is associated with the development of obesity, insulin resistance, and type II diabetes. High plasma concentrations of amino acids have been found to correlate with insulin resistance. At the cellular level, excess amino acids impair insulin signaling, the mechanisms of which are not fully understood. Here, we report that STAT3 plays a key role in amino acid dampening of insulin signaling in hepatic cells. Excess amino acids inhibited insulin-stimulated Akt phosphorylation a...

  11. Phosphatidic acid, a versatile water-stress signal in roots

    Fionn eMcLoughlin

    2013-12-01

    Full Text Available Adequate water supply is of utmost importance for growth and reproduction of plants. In order to cope with water deprivation, plants have to adapt their development and metabolism to ensure survival. To maximize water use efficiency, plants use a large array of signaling mediators such as hormones, protein kinases and phosphatases, Ca2+, reactive oxygen species and low abundant phospholipids that together form complex signaling cascades. Phosphatidic acid (PA is a signaling lipid that rapidly accumulates in response to a wide array of abiotic stress stimuli. PA formation provides the cell with spatial and transient information about the external environment by acting as a protein-docking site in cellular membranes. PA reportedly binds to a number of proteins that play a role during water limiting conditions, such as drought and salinity and has been shown to play an important role in maintaining root system architecture. Members of two osmotic stress-activated protein kinase families, sucrose non-fermenting 1-related protein kinase 2 (SnRK2 and mitogen activated protein kinases (MAPKs were recently shown bind PA and are also involved in the maintenance of root system architecture and salinity stress tolerance. In addition, PA regulates several proteins involved in abscisic acid (ABA-signaling. PA-dependent recruitment of glyceraldehyde-3-phosphate dehydrogenase (GAPDH under water limiting conditions indicates a role in regulating metabolic processes. Finally, a recent study also shows the PA recruits the clathrin heavy chain and a potassium channel subunit, hinting towards additional roles in cellular trafficking and potassium homeostasis. Taken together, the rapidly increasing number of proteins reported to interact with PA implies a broad role for this versatile signaling phospholipid in mediating salt and water stress responses.

  12. Evolution of Abscisic Acid Synthesis and Signaling Mechanisms

    Hauser, Felix; Waadt, Rainer; Schroeder, Julian I.

    2011-01-01

    The plant hormone abscisic acid (ABA) mediates seed dormancy, controls seedling development and triggers tolerance to abiotic stresses, including drought. Core ABA signaling components consist of a recently identified group of ABA receptor proteins of the PYRABACTIN RESISTANCE (PYR)/REGULATORY COMPONENT OF ABA RECEPTOR (RCAR) family that act as negative regulators of members of the PROTEIN PHOSPHATASE 2C (PP2C) family. Inhibition of PP2C activity enables activation of SNF1-RELATED KINASE 2 (SnRK2) protein kinases, which target downstream components, including transcription factors, ion channels and NADPH oxidases. These and other components form a complex ABA signaling network. Here, an in depth analysis of the evolution of components in this ABA signaling network shows that (i) PYR/RCAR ABA receptor and ABF-type transcription factor families arose during land colonization of plants and are not found in algae and other species, (ii) ABA biosynthesis enzymes have evolved to plant- and fungal-specific forms, leading to different ABA synthesis pathways, (iii) existing stress signaling components, including PP2C phosphatases and SnRK kinases, were adapted for novel roles in this plant-specific network to respond to water limitation. In addition, evolutionarily conserved secondary structures in the PYR/RCAR ABA receptor family are visualized. PMID:21549957

  13. Kinome profiling reveals an interaction between jasmonate, salicylate and light control of hyponastic petiole growth in Arabidopsis thaliana.

    Tita Ritsema

    Full Text Available Plants defend themselves against infection by biotic attackers by producing distinct phytohormones. Especially jasmonic acid (JA and salicylic acid (SA are well known defense-inducing hormones. Here, the effects of MeJA and SA on the Arabidopsis thaliana kinome were monitored using PepChip arrays containing kinase substrate peptides to analyze posttranslational interactions in MeJA and SA signaling pathways and to test if kinome profiling can provide leads to predict posttranslational events in plant signaling. MeJA and SA mediate differential phosphorylation of substrates for many kinase families. Also some plant specific substrates were differentially phosphorylated, including peptides derived from Phytochrome A, and Photosystem II D protein. This indicates that MeJA and SA mediate cross-talk between defense signaling and light responses. We tested the predicted effects of MeJA and SA using light-mediated upward leaf movement (differential petiole growth also called hyponastic growth. We found that MeJA, infestation by the JA-inducing insect herbivore Pieris rapae, and SA suppressed low light-induced hyponastic growth. MeJA and SA acted in a synergistic fashion via two (partially divergent signaling routes. This work demonstrates that kinome profiling using PepChip arrays can be a valuable complementary ∼omics tool to give directions towards predicting behavior of organisms after a given stimulus and can be used to obtain leads for physiological relevant phenomena in planta.

  14. WRKY transcription factors: key components in abscisic acid signalling.

    Rushton, Deena L; Tripathi, Prateek; Rabara, Roel C; Lin, Jun; Ringler, Patricia; Boken, Ashley K; Langum, Tanner J; Smidt, Lucas; Boomsma, Darius D; Emme, Nicholas J; Chen, Xianfeng; Finer, John J; Shen, Qingxi J; Rushton, Paul J

    2012-01-01

    WRKY transcription factors (TFs) are key regulators of many plant processes, including the responses to biotic and abiotic stresses, senescence, seed dormancy and seed germination. For over 15 years, limited evidence has been available suggesting that WRKY TFs may play roles in regulating plant responses to the phytohormone abscisic acid (ABA), notably some WRKY TFs are ABA-inducible repressors of seed germination. However, the roles of WRKY TFs in other aspects of ABA signalling, and the mechanisms involved, have remained unclear. Recent significant progress in ABA research has now placed specific WRKY TFs firmly in ABA-responsive signalling pathways, where they act at multiple levels. In Arabidopsis, WRKY TFs appear to act downstream of at least two ABA receptors: the cytoplasmic PYR/PYL/RCAR-protein phosphatase 2C-ABA complex and the chloroplast envelope-located ABAR-ABA complex. In vivo and in vitro promoter-binding studies show that the target genes for WRKY TFs that are involved in ABA signalling include well-known ABA-responsive genes such as ABF2, ABF4, ABI4, ABI5, MYB2, DREB1a, DREB2a and RAB18. Additional well-characterized stress-inducible genes such as RD29A and COR47 are also found in signalling pathways downstream of WRKY TFs. These new insights also reveal that some WRKY TFs are positive regulators of ABA-mediated stomatal closure and hence drought responses. Conversely, many WRKY TFs are negative regulators of seed germination, and controlling seed germination appears a common function of a subset of WRKY TFs in flowering plants. Taken together, these new data demonstrate that WRKY TFs are key nodes in ABA-responsive signalling networks. © 2011 The Authors. Plant Biotechnology Journal © 2011 Society for Experimental Biology, Association of Applied Biologists and Blackwell Publishing Ltd.

  15. A stilbene synthase allele from a Chinese wild grapevine confers resistance to powdery mildew by recruiting salicylic acid signalling for efficient defence.

    Jiao, Yuntong; Xu, Weirong; Duan, Dong; Wang, Yuejin; Nick, Peter

    2016-10-01

    Stilbenes are central phytoalexins in Vitis, and induction of the key enzyme stilbene synthase (STS) is pivotal for disease resistance. Here, we address the potential for breeding resistance using an STS allele isolated from Chinese wild grapevine Vitis pseudoreticulata (VpSTS) by comparison with its homologue from Vitis vinifera cv. 'Carigane' (VvSTS). Although the coding regions of both alleles are very similar (>99% identity on the amino acid level), the promoter regions are significantly different. By expression in Arabidopsis as a heterologous system, we show that the allele from the wild Chinese grapevine can confer accumulation of stilbenes and resistance against the powdery mildew Golovinomyces cichoracearum, whereas the allele from the vinifera cultivar cannot. To dissect the upstream signalling driving the activation of this promoter, we used a dual-luciferase reporter system in a grapevine cell culture. We show elevated responsiveness of the promoter from the wild grape to salicylic acid (SA) and to the pathogen-associated molecular pattern (PAMP) flg22, equal induction of both alleles by jasmonic acid (JA), and a lack of response to the cell death-inducing elicitor Harpin. This elevated SA response of the VpSTS promoter depends on calcium influx, oxidative burst by RboH, mitogen-activated protein kinase (MAPK) signalling, and JA synthesis. We integrate the data in the context of a model where the resistance of V. pseudoreticulata is linked to a more efficient recruitment of SA signalling for phytoalexin synthesis. © The Author 2016. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  16. Cerato-platanin induces resistance in Arabidopsis leaves through stomatal perception, overexpression of salicylic acid- and ethylene-signalling genes and camalexin biosynthesis.

    Baccelli, Ivan; Lombardi, Lara; Luti, Simone; Bernardi, Rodolfo; Picciarelli, Piero; Scala, Aniello; Pazzagli, Luigia

    2014-01-01

    Microbe-associated molecular patterns (MAMPs) lead to the activation of the first line of plant defence. Few fungal molecules are universally qualified as MAMPs, and proteins belonging to the cerato-platanin protein (CPP) family seem to possess these features. Cerato-platanin (CP) is the name-giving protein of the CPP family and is produced by Ceratocystis platani, the causal agent of the canker stain disease of plane trees (Platanus spp.). On plane tree leaves, the biological activity of CP has been widely studied. Once applied on the leaf surface, CP acts as an elicitor of defence responses. The molecular mechanism by which CP elicits leaves is still unknown, and the protective effect of CP against virulent pathogens has not been clearly demonstrated. In the present study, we tried to address these questions in the model plant Arabidopsis thaliana. Our results suggest that stomata rapidly sense CP since they responded to the treatment with ROS signalling and stomatal closure, and that CP triggers salicylic acid (SA)- and ethylene (ET)-signalling pathways, but not the jasmonic acid (JA)-signalling pathway, as revealed by the expression pattern of 20 marker genes. Among these, EDS1, PAD4, NPR1, GRX480, WRKY70, ACS6, ERF1a/b, COI1, MYC2, PDF1.2a and the pathogenesis-related (PR) genes 1-5. CP rapidly induced MAPK phosphorylation and induced the biosynthesis of camalexin within 12 hours following treatment. The induction of localised resistance was shown by a reduced susceptibility of the leaves to the infection with Botrytis cinerea and Pseudomonas syringae pv. tomato. These results contribute to elucidate the key steps of the signalling process underlying the resistance induction in plants by CP and point out the central role played by the stomata in this process.

  17. Cerato-platanin induces resistance in Arabidopsis leaves through stomatal perception, overexpression of salicylic acid- and ethylene-signalling genes and camalexin biosynthesis.

    Ivan Baccelli

    Full Text Available Microbe-associated molecular patterns (MAMPs lead to the activation of the first line of plant defence. Few fungal molecules are universally qualified as MAMPs, and proteins belonging to the cerato-platanin protein (CPP family seem to possess these features. Cerato-platanin (CP is the name-giving protein of the CPP family and is produced by Ceratocystis platani, the causal agent of the canker stain disease of plane trees (Platanus spp.. On plane tree leaves, the biological activity of CP has been widely studied. Once applied on the leaf surface, CP acts as an elicitor of defence responses. The molecular mechanism by which CP elicits leaves is still unknown, and the protective effect of CP against virulent pathogens has not been clearly demonstrated. In the present study, we tried to address these questions in the model plant Arabidopsis thaliana. Our results suggest that stomata rapidly sense CP since they responded to the treatment with ROS signalling and stomatal closure, and that CP triggers salicylic acid (SA- and ethylene (ET-signalling pathways, but not the jasmonic acid (JA-signalling pathway, as revealed by the expression pattern of 20 marker genes. Among these, EDS1, PAD4, NPR1, GRX480, WRKY70, ACS6, ERF1a/b, COI1, MYC2, PDF1.2a and the pathogenesis-related (PR genes 1-5. CP rapidly induced MAPK phosphorylation and induced the biosynthesis of camalexin within 12 hours following treatment. The induction of localised resistance was shown by a reduced susceptibility of the leaves to the infection with Botrytis cinerea and Pseudomonas syringae pv. tomato. These results contribute to elucidate the key steps of the signalling process underlying the resistance induction in plants by CP and point out the central role played by the stomata in this process.

  18. In vitro reconstitution of an abscisic acid signalling pathway

    Fujii, Hiroaki; Chinnusamy, Viswanathan; Rodrigues, Americo; Rubio, Silvia; Antoni, Regina; Park, Sang-Youl; Cutler, Sean R.; Sheen, Jen; Rodriguez, Pedro L.; Zhu, Jian-Kang

    2009-01-01

    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.

  19. In vitro reconstitution of an abscisic acid signalling pathway

    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.

  20. Airborne signals by Trichoderma fungi stimulate iron uptake responses in roots resulting in priming of jasmonic acid-dependent defences in shoots of Arabidopsis thaliana and Solanum lycopersicum

    Martínez-Medina, Ainhoa; Van Wees, Saskia C M; Pieterse, Corné M J

    2017-01-01

    Root colonization by Trichoderma fungi can trigger induced systemic resistance (ISR). In Arabidopsis, Trichoderma-ISR relies on the transcription factor MYB72, which plays a dual role in the onset of ISR and the activation of Fe uptake responses. Volatile compounds (VCs) from rhizobacteria are

  1. Lysophosphatidic acid acyltransferase beta regulates mTOR signaling.

    Michelle A Blaskovich

    Full Text Available Lysophosphatidic acid acyltransferase (LPAAT-β is a phosphatidic acid (PA generating enzyme that plays an essential role in triglyceride synthesis. However, LPAAT-β is now being studied as an important regulator of cell growth and differentiation and as a potential therapeutic target in cancer since PA is necessary for the activity of key proteins such as Raf, PKC-ζ and mTOR. In this report we determine the effect of LPAAT-β silencing with siRNA in pancreatic adenocarcinoma cell lines. We show for the first time that LPAAT-β knockdown inhibits proliferation and anchorage-independent growth of pancreatic cancer cells. This is associated with inhibition of signaling by mTOR as determined by levels of mTORC1- and mTORC2-specific phosphorylation sites on 4E-BP1, S6K and Akt. Since PA regulates the activity of mTOR by modulating its binding to FKBP38, we explored the possibility that LPAAT-β might regulate mTOR by affecting its association with FKBP38. Coimmunoprecipitation studies of FKBP38 with mTOR show increased levels of FKBP38 associated with mTOR when LPAAT-β protein levels are knocked down. Furthermore, depletion of LPAAT-β results in increased Lipin 1 nuclear localization which is associated with increased nuclear eccentricity, a nuclear shape change that is dependent on mTOR, further confirming the ability of LPAAT-β to regulate mTOR function. Our results provide support for the hypothesis that PA generated by LPAAT-β regulates mTOR signaling. We discuss the implications of these findings for using LPAAT-β as a therapeutic target.

  2. Abscisic-acid-induced cellular apoptosis and differentiation in glioma via the retinoid acid signaling pathway.

    Zhou, Nan; Yao, Yu; Ye, Hongxing; Zhu, Wei; Chen, Liang; Mao, Ying

    2016-04-15

    Retinoid acid (RA) plays critical roles in regulating differentiation and apoptosis in a variety of cancer cells. Abscisic acid (ABA) and RA are direct derivatives of carotenoids and share structural similarities. Here we proposed that ABA may also play a role in cellular differentiation and apoptosis by sharing a similar signaling pathway with RA that may be involved in glioma pathogenesis. We reported for the first time that the ABA levels were twofold higher in low-grade gliomas compared with high-grade gliomas. In glioma tissues, there was a positive correlation between the ABA levels and the transcription of cellular retinoic acid-binding protein 2 (CRABP2) and a negative correlation between the ABA levels and transcription of fatty acid-binding protein 5 (FABP5). ABA treatment induced a significant increase in the expression of CRABP2 and a decrease in the expression of peroxisome proliferator-activated receptor (PPAR) in glioblastoma cells. Remarkably, both cellular apoptosis and differentiation were increased in the glioblastoma cells after ABA treatment. ABA-induced cellular apoptosis and differentiation were significantly reduced by selectively silencing RAR-α, while RAR-α overexpression exaggerated the ABA-induced effects. These results suggest that ABA may play a role in the pathogenesis of glioma by promoting cellular apoptosis and differentiation through the RA signaling pathway. © 2015 UICC.

  3. Abscisic acid perception and signaling: structural mechanisms and applications

    Ng, Ley Moy; Melcher, Karsten; Teh, Bin Tean; Xu, H Eric

    2014-01-01

    Adverse environmental conditions are a threat to agricultural yield and therefore exert a global effect on livelihood, health and the economy. Abscisic acid (ABA) is a vital plant hormone that regulates abiotic stress tolerance, thereby allowing plants to cope with environmental stresses. Previously, attempts to develop a complete understanding of the mechanisms underlying ABA signaling have been hindered by difficulties in the identification of bona fide ABA receptors. The discovery of the PYR/PYL/RCAR family of ABA receptors therefore represented a major milestone in the effort to overcome these roadblocks; since then, many structural and functional studies have provided detailed insights into processes ranging from ABA perception to the activation of ABA-responsive gene transcription. This understanding of the mechanisms of ABA perception and signaling has served as the basis for recent, preliminary developments in the genetic engineering of stress-resistant crops as well as in the design of new synthetic ABA agonists, which hold great promise for the agricultural enhancement of stress tolerance. PMID:24786231

  4. Effects of Methyl Jasmonate on the Composition of Volatile Compounds in Pyropia yezoensis

    He, Lihong; Wang, Liang; Wang, Linfang; Shen, Songdong

    2018-04-01

    Volatile organic compounds in marine algae have been reported to comprise characteristic flavor of algae and play an important role in their growth, development and defensive response. Yet their biogeneration remain largely unknown. Here we studied the composition of volatile compouds in Pyropia yezoensis and their variations in response to methyl jasmonate (MeJA) and diethyldithiocarbamic acid (DIECA) treatment using gas chromatography-mass spectrometry (GC-MS). A total of 44 compounds belonging to the following chemical classes (n) were identified, including aldehydes (11), alcohols (8), acids and esters (6), alkanes (5), ketones (5), alkenes (3), and S- or N-containing miscellaneous compounds (6). External treatment with plant hormone MeJA increased the content of 1-dodecanol, 4-heptenal, and 2-propenoic acid-2-methyl dodecylester, but decreased the content of phytol, 3-heptadecene, 2-pentadecanone, and isophytol. When pretreated with DIECA, an inhibitor of the octadecanoid pathway leading to the biosynthesis of endogeneous jasmonates and some secondary metabolites, phytol and isophytol were increased, while 4-heptenal, 1-dodecanol, and 2-propenoic acid-2-methyl dodecylester were decreased, both of which were negatively correlated with their variations under MeJA treatment. Collectively, these results suggest that MeJA does affect the volatile composition of P. yezoensis, and the octadecanoid pathway together with endogenous jasmonate pathway may be involved in the biosynthesis of volatile compounds, thereby providing some preliminary envision on the composition and biogeneration of volatile compounds in P. yezoensis.

  5. Jasmonates act positively in adventitious root formation in petunia cuttings

    Lischweski, Sandra; Muchow, Anne; Guthörl, Daniela; Hause, Bettina

    2015-01-01

    Background Petunia is a model to study the process of adventitious root (AR) formation on leafy cuttings. Excision of cuttings leads to a transient increase in jasmonates, which is regarded as an early, transient and critical event for rooting. Here, the role of jasmonates in AR formation on petunia cuttings has been studied by a reverse genetic approach. Results To reduce the endogenous levels of jasmonates, transgenic plants were generated expressing a Petunia hybrida ALLENE OXIDE CYCLASE (...

  6. Effect of exogenous methyl jasmonate on growth, gas exchange and chlorophyll contents of soybean subjected to drought

    Anjum, Shakeel Ahmad; Xie, Xiao-yu; Farooq, Muhammad; Wang, Long-chang; Xue, Lan-lan; Shahbaz, Muhammad; Salhab, Jalaladeen

    2011-01-01

    Drought is considered as one of the major constraints to crop production worldwide. Methyl jasmonate (MJ) is a plant-signaling molecule that elicits a wide variety of plant responses ranging from morphological to molecular level. A pot-culture study was undertaken to investigate the possible role of

  7. Jasmonate ZIM-domain (JAZ protein regulates host and nonhost pathogen-induced cell death in tomato and Nicotiana benthamiana.

    Yasuhiro Ishiga

    Full Text Available The nonhost-specific phytotoxin coronatine (COR produced by several pathovars of Pseudomonas syringae functions as a jasmonic acid-isoleucine (JA-Ile mimic and contributes to disease development by suppressing plant defense responses and inducing reactive oxygen species in chloroplast. It has been shown that the F-box protein CORONATINE INSENSITIVE 1 (COI1 is the receptor for COR and JA-Ile. JASMONATE ZIM DOMAIN (JAZ proteins act as negative regulators for JA signaling in Arabidopsis. However, the physiological significance of JAZ proteins in P. syringae disease development and nonhost pathogen-induced hypersensitive response (HR cell death is not completely understood. In this study, we identified JAZ genes from tomato, a host plant for P. syringae pv. tomato DC3000 (Pst DC3000, and examined their expression profiles in response to COR and pathogens. Most JAZ genes were induced by COR treatment or inoculation with COR-producing Pst DC3000, but not by the COR-defective mutant DB29. Tomato SlJAZ2, SlJAZ6 and SlJAZ7 interacted with SlCOI1 in a COR-dependent manner. Using virus-induced gene silencing (VIGS, we demonstrated that SlJAZ2, SlJAZ6 and SlJAZ7 have no effect on COR-induced chlorosis in tomato and Nicotiana benthamiana. However, SlJAZ2-, SlJAZ6- and SlJAZ7-silenced tomato plants showed enhanced disease-associated cell death to Pst DC3000. Furthermore, we found delayed HR cell death in response to the nonhost pathogen Pst T1 or a pathogen-associated molecular pattern (PAMP, INF1, in SlJAZ2- and SlJAZ6-silenced N. benthamiana. These results suggest that tomato JAZ proteins regulate the progression of cell death during host and nonhost interactions.

  8. Regulatory signals for intestinal amino acid transporters and peptidases

    Ferraris, R.P.; Kwan, W.W.; Diamond, J.

    1988-01-01

    Dietary protein ultimately regulates many processes involved in protein digestion, but it is often unclear whether proteins themselves, peptides, or amino acids (AAs) are the proximate regulatory signal. Hence the authors compared several processes involved in protein digestion in mice adapted to one of three rations, identical except for containing 54% of either casein, a partial hydrolysate of casein, or a free AA mixture simulating a complete hydrolysate of casein. The authors measured brush-border uptakes of seven AAs that variously serve as substrates for four AA transporters, and brush-border and cytosolic activities of four peptidases. The three rations yielded essentially the same AA uptake rates. Peptidase activities tended to be lower on the AA ration than on the protein ration. In other studies, all three rations yielded the same rates of brush-border peptide uptake; protein is only modestly more effective than AAs at inducing synthesis of pancreatic proteases; and, depending on the animal species, protein is either much less or much more effective than AAs at stimulating release of cholecystokinin and hence of pancreatic enzymes. Thus the regulators of each process involved in protein digestion are not necessarily that process's substrate

  9. Redox signaling in plants.

    Foyer, Christine H; Noctor, Graham

    2013-06-01

    Our aim is to deliver an authoritative and challenging perspective of current concepts in plant redox signaling, focusing particularly on the complex interface between the redox and hormone-signaling pathways that allow precise control of plant growth and defense in response to metabolic triggers and environmental constraints and cues. Plants produce significant amounts of singlet oxygen and other reactive oxygen species (ROS) as a result of photosynthetic electron transport and metabolism. Such pathways contribute to the compartment-specific redox-regulated signaling systems in plant cells that convey information to the nucleus to regulate gene expression. Like the chloroplasts and mitochondria, the apoplast-cell wall compartment makes a significant contribution to the redox signaling network, but unlike these organelles, the apoplast has a low antioxidant-buffering capacity. The respective roles of ROS, low-molecular antioxidants, redox-active proteins, and antioxidant enzymes are considered in relation to the functions of plant hormones such as salicylic acid, jasmonic acid, and auxin, in the composite control of plant growth and defense. Regulation of redox gradients between key compartments in plant cells such as those across the plasma membrane facilitates flexible and multiple faceted opportunities for redox signaling that spans the intracellular and extracellular environments. In conclusion, plants are recognized as masters of the art of redox regulation that use oxidants and antioxidants as flexible integrators of signals from metabolism and the environment.

  10. Opposing effects of bile acids deoxycholic acid and ursodeoxycholic acid on signal transduction pathways in oesophageal cancer cells.

    Abdel-Latif, Mohamed M; Inoue, Hiroyasu; Reynolds, John V

    2016-09-01

    Ursodeoxycholic acid (UDCA) was reported to reduce bile acid toxicity, but the mechanisms underlying its cytoprotective effects are not fully understood. The aim of the present study was to examine the effects of UDCA on the modulation of deoxycholic acid (DCA)-induced signal transduction in oesophageal cancer cells. Nuclear factor-κB (NF-κB) and activator protein-1 (AP-1) activity was assessed using a gel shift assay. NF-κB activation and translocation was performed using an ELISA-based assay and immunofluorescence analysis. COX-2 expression was analysed by western blotting and COX-2 promoter activity was assessed by luciferase assay. DCA induced NF-κB and AP-1 DNA-binding activities in SKGT-4 and OE33 cells. UDCA pretreatment inhibited DCA-induced NF-κB and AP-1 activation and NF-κB translocation. This inhibitory effect was coupled with a blockade of IκB-α degradation and inhibition of phosphorylation of IKK-α/β and ERK1/2. Moreover, UDCA pretreatment inhibited COX-2 upregulation. Using transient transfection of the COX-2 promoter, UDCA pretreatment abrogated DCA-induced COX-2 promoter activation. In addition, UDCA protected oesophageal cells from the apoptotic effects of deoxycholate. Our findings indicate that UDCA inhibits DCA-induced signalling pathways in oesophageal cancer cells. These data indicate a possible mechanistic role for the chemopreventive actions of UDCA in oesophageal carcinogenesis.

  11. Differential regulation of EGFR-MAPK signaling by deoxycholic acid (DCA) and ursodeoxycholic acid (UDCA) in colon cancer.

    Centuori, Sara M; Martinez, Jesse D

    2014-10-01

    A high-fat diet coincides with increased levels of bile acids. This increase in bile acids, particularly deoxycholic acid (DCA), has been strongly associated with the development of colon cancer. Conversely, ursodeoxycholic acid (UDCA) may have chemopreventive properties. Although structurally similar, DCA and UDCA present different biological and pathological effects in colon cancer progression. The differential regulation of cancer by these two bile acids is not yet fully understood. However, one possible explanation for their diverging effects is their ability to differentially regulate signaling pathways involved in the multistep progression of colon cancer, such as the epidermal growth factor receptor (EGFR)-mitogen-activated protein kinase (MAPK) pathway. This review will examine the biological effects of DCA and UDCA on colon cancer development, as well as the diverging effects of these bile acids on the oncogenic signaling pathways that play a role in colon cancer development, with a particular emphasis on bile acid regulation of the EGFR-MAPK pathway.

  12. Micelle-assisted signaling of peracetic acid by the oxidation of pyreneboronic acid via monomer-excimer switching.

    Choi, Jiyoung; Lee, Hyo Jin; Cho, Min Jeoung; Chang, Suk-Kyu

    2015-08-15

    A simple fluorescent probe for the industrial oxidant peracetic acid (PAA) was investigated. PAA-assisted oxidative conversion of pyrene-1-boronic acid into 1-hydroxypyrene was used as the signaling tool. Pyreneboronic acid was found to display selective signaling behavior, being more responsive to PAA than to other commonly used practical oxidants such as H2O2 and HOCl. The changes in pyrene monomer fluorescence to excimer were used in the quantitative analysis of PAA. When using the surfactant hexadecyltrimethylammonium bromide as a micellar additive, the signaling of PAA was markedly enhanced. Selective fluorescence signaling of PAA by pyrene-1-boronic acid with a detection limit of 1.5×10(-6)M in aqueous environment was successfully achieved. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. Retinoic acid signalling in thymocytes regulates T cell development

    Wendland, Kerstin; Sitnik, Katarzyna Maria; Kotarsky, Knut

    in the regulatory regions of targetgenes. RA has been reported to play a direct role in regulating multiple aspects of peripheralT cell responses1, but whether endogenous RA signalling occurs in developingthymocytes and the potential impact of such signals in regulating T cell developmentremains unclear. To address......RARα. This blocks RA signalling in developing thymocytes from the DN3/4 stageonwards and thus allows us to study the role of RA in T cell development...

  14. Enhancement of arachidonic acid signaling pathway by nicotinic acid receptor HM74A

    Tang, Yuting; Zhou, Lubing; Gunnet, Joseph W.; Wines, Pamela G.; Cryan, Ellen V.; Demarest, Keith T.

    2006-01-01

    HM74A is a G protein-coupled receptor for nicotinic acid (niacin), which has been used clinically to treat dyslipidemia for decades. The molecular mechanisms whereby niacin exerts its pleiotropic effects on lipid metabolism remain largely unknown. In addition, the most common side effect in niacin therapy is skin flushing that is caused by prostaglandin release, suggesting that the phospholipase A 2 (PLA 2 )/arachidonic acid (AA) pathway is involved. Various eicosanoids have been shown to activate peroxisome-proliferator activated receptors (PPAR) that play a diverse array of roles in lipid metabolism. To further elucidate the potential roles of HM74A in mediating the therapeutic effects and/or side effects of niacin, we sought to explore the signaling events upon HM74A activation. Here we demonstrated that HM74A synergistically enhanced UTP- and bradykinin-mediated AA release in a pertussis toxin-sensitive manner in A431 cells. Activation of HM74A also led to Ca 2+ -mobilization and enhanced bradykinin-promoted Ca 2+ -mobilization through Gi protein. While HM74A increased ERK1/2 activation by the bradykinin receptor, it had no effects on UTP-promoted ERK1/2 activation.Furthermore, UTP- and bradykinin-mediated AA release was significantly decreased in the presence of both MAPK kinase inhibitor PD 098059 and PKC inhibitor GF 109203X. However, the synergistic effects of HM74A were not dramatically affected by co-treatment with both inhibitors, indicating the cross-talk occurred at the receptor level. Finally, stimulation of A431 cells transiently transfected with PPRE-luciferase with AA significantly induced luciferase activity, mimicking the effects of PPARγ agonist rosiglitazone, suggesting that alteration of AA signaling pathway can regulate gene expression via endogenous PPARs

  15. Enhancement of arachidonic acid signaling pathway by nicotinic acid receptor HM74A

    Tang, Yuting [Endocrine Therapeutics and Metabolic Disorders, Johnson and Johnson Pharmaceutical Research and Development, L.L.C., 1000 Rt. 202, Raritan, NJ 08869 (United States); Zhou, Lubing [Endocrine Therapeutics and Metabolic Disorders, Johnson and Johnson Pharmaceutical Research and Development, L.L.C., 1000 Rt. 202, Raritan, NJ 08869 (United States); Gunnet, Joseph W [Endocrine Therapeutics and Metabolic Disorders, Johnson and Johnson Pharmaceutical Research and Development, L.L.C., 1000 Rt. 202, Raritan, NJ 08869 (United States); Wines, Pamela G [Endocrine Therapeutics and Metabolic Disorders, Johnson and Johnson Pharmaceutical Research and Development, L.L.C., 1000 Rt. 202, Raritan, NJ 08869 (United States); Cryan, Ellen V [Endocrine Therapeutics and Metabolic Disorders, Johnson and Johnson Pharmaceutical Research and Development, L.L.C., 1000 Rt. 202, Raritan, NJ 08869 (United States); Demarest, Keith T [Endocrine Therapeutics and Metabolic Disorders, Johnson and Johnson Pharmaceutical Research and Development, L.L.C., 1000 Rt. 202, Raritan, NJ 08869 (United States)

    2006-06-23

    HM74A is a G protein-coupled receptor for nicotinic acid (niacin), which has been used clinically to treat dyslipidemia for decades. The molecular mechanisms whereby niacin exerts its pleiotropic effects on lipid metabolism remain largely unknown. In addition, the most common side effect in niacin therapy is skin flushing that is caused by prostaglandin release, suggesting that the phospholipase A{sub 2} (PLA{sub 2})/arachidonic acid (AA) pathway is involved. Various eicosanoids have been shown to activate peroxisome-proliferator activated receptors (PPAR) that play a diverse array of roles in lipid metabolism. To further elucidate the potential roles of HM74A in mediating the therapeutic effects and/or side effects of niacin, we sought to explore the signaling events upon HM74A activation. Here we demonstrated that HM74A synergistically enhanced UTP- and bradykinin-mediated AA release in a pertussis toxin-sensitive manner in A431 cells. Activation of HM74A also led to Ca{sup 2+}-mobilization and enhanced bradykinin-promoted Ca{sup 2+}-mobilization through Gi protein. While HM74A increased ERK1/2 activation by the bradykinin receptor, it had no effects on UTP-promoted ERK1/2 activation.Furthermore, UTP- and bradykinin-mediated AA release was significantly decreased in the presence of both MAPK kinase inhibitor PD 098059 and PKC inhibitor GF 109203X. However, the synergistic effects of HM74A were not dramatically affected by co-treatment with both inhibitors, indicating the cross-talk occurred at the receptor level. Finally, stimulation of A431 cells transiently transfected with PPRE-luciferase with AA significantly induced luciferase activity, mimicking the effects of PPAR{gamma} agonist rosiglitazone, suggesting that alteration of AA signaling pathway can regulate gene expression via endogenous PPARs.

  16. Role of tomato lipoxygenase D in wound-induced jasmonate biosynthesis and plant immunity to insect herbivores.

    Yan, Liuhua; Zhai, Qingzhe; Wei, Jianing; Li, Shuyu; Wang, Bao; Huang, Tingting; Du, Minmin; Sun, Jiaqiang; Kang, Le; Li, Chang-Bao; Li, Chuanyou

    2013-01-01

    In response to insect attack and mechanical wounding, plants activate the expression of genes involved in various defense-related processes. A fascinating feature of these inducible defenses is their occurrence both locally at the wounding site and systemically in undamaged leaves throughout the plant. Wound-inducible proteinase inhibitors (PIs) in tomato (Solanum lycopersicum) provide an attractive model to understand the signal transduction events leading from localized injury to the systemic expression of defense-related genes. Among the identified intercellular molecules in regulating systemic wound response of tomato are the peptide signal systemin and the oxylipin signal jasmonic acid (JA). The systemin/JA signaling pathway provides a unique opportunity to investigate, in a single experimental system, the mechanism by which peptide and oxylipin signals interact to coordinate plant systemic immunity. Here we describe the characterization of the tomato suppressor of prosystemin-mediated responses8 (spr8) mutant, which was isolated as a suppressor of (pro)systemin-mediated signaling. spr8 plants exhibit a series of JA-dependent immune deficiencies, including the inability to express wound-responsive genes, abnormal development of glandular trichomes, and severely compromised resistance to cotton bollworm (Helicoverpa armigera) and Botrytis cinerea. Map-based cloning studies demonstrate that the spr8 mutant phenotype results from a point mutation in the catalytic domain of TomLoxD, a chloroplast-localized lipoxygenase involved in JA biosynthesis. We present evidence that overexpression of TomLoxD leads to elevated wound-induced JA biosynthesis, increased expression of wound-responsive genes and, therefore, enhanced resistance to insect herbivory attack and necrotrophic pathogen infection. These results indicate that TomLoxD is involved in wound-induced JA biosynthesis and highlight the application potential of this gene for crop protection against insects and

  17. Role of tomato lipoxygenase D in wound-induced jasmonate biosynthesis and plant immunity to insect herbivores.

    Liuhua Yan

    Full Text Available In response to insect attack and mechanical wounding, plants activate the expression of genes involved in various defense-related processes. A fascinating feature of these inducible defenses is their occurrence both locally at the wounding site and systemically in undamaged leaves throughout the plant. Wound-inducible proteinase inhibitors (PIs in tomato (Solanum lycopersicum provide an attractive model to understand the signal transduction events leading from localized injury to the systemic expression of defense-related genes. Among the identified intercellular molecules in regulating systemic wound response of tomato are the peptide signal systemin and the oxylipin signal jasmonic acid (JA. The systemin/JA signaling pathway provides a unique opportunity to investigate, in a single experimental system, the mechanism by which peptide and oxylipin signals interact to coordinate plant systemic immunity. Here we describe the characterization of the tomato suppressor of prosystemin-mediated responses8 (spr8 mutant, which was isolated as a suppressor of (prosystemin-mediated signaling. spr8 plants exhibit a series of JA-dependent immune deficiencies, including the inability to express wound-responsive genes, abnormal development of glandular trichomes, and severely compromised resistance to cotton bollworm (Helicoverpa armigera and Botrytis cinerea. Map-based cloning studies demonstrate that the spr8 mutant phenotype results from a point mutation in the catalytic domain of TomLoxD, a chloroplast-localized lipoxygenase involved in JA biosynthesis. We present evidence that overexpression of TomLoxD leads to elevated wound-induced JA biosynthesis, increased expression of wound-responsive genes and, therefore, enhanced resistance to insect herbivory attack and necrotrophic pathogen infection. These results indicate that TomLoxD is involved in wound-induced JA biosynthesis and highlight the application potential of this gene for crop protection against

  18. Control of Biofilms with the Fatty Acid Signaling Molecule cis-2-Decenoic Acid

    Cláudia N. H. Marques

    2015-11-01

    Full Text Available Biofilms are complex communities of microorganisms in organized structures attached to surfaces. Importantly, biofilms are a major cause of bacterial infections in humans, and remain one of the most significant challenges to modern medical practice. Unfortunately, conventional therapies have shown to be inadequate in the treatment of most chronic biofilm infections based on the extraordinary innate tolerance of biofilms to antibiotics. Antagonists of quorum sensing signaling molecules have been used as means to control biofilms. QS and other cell-cell communication molecules are able to revert biofilm tolerance, prevent biofilm formation and disrupt fully developed biofilms, albeit with restricted effectiveness. Recently however, it has been demonstrated that Pseudomonas aeruginosa produces a small messenger molecule cis-2-decenoic acid (cis-DA that shows significant promise as an effective adjunctive to antimicrobial treatment of biofilms. This molecule is responsible for induction of the native biofilm dispersion response in a range of Gram-negative and Gram-positive bacteria and in yeast, and has been shown to reverse persistence, increase microbial metabolic activity and significantly enhance the cidal effects of conventional antimicrobial agents. In this manuscript, the use of cis-2-decenoic acid as a novel agent for biofilm control is discussed. Stimulating the biofilm dispersion response as a novel antimicrobial strategy holds significant promise for enhanced treatment of infections and in the prevention of biofilm formation.

  19. Retinoic acid signalling in thymocytes regulates T cell development

    Wendland, Kerstin; Sitnik, Katarzyna Maria; Kotarsky, Knut

    . Here, using a RA sensitive reporter mouse model, we demonstrate that endogenous RAR responses are induced in CD69+CD4+CD8lo and CD69+CD4+CD8+ thymocytes undergoing positive selection and lineage commitment, and continue to be present in both CD4+ and CD8+ single positive (SP) cells, with RA signaling...... further enhanced in recently generated CD69+ CD4+ SP cells. To address the potential biological significance of RA signaling in developing thymocytes, we evaluated T cell development in CD4Cre-dnRAR mice, where RA signaling is blocked in thymocytes from the CD4+CD8+ double positive (DP) stage onwards due...

  20. Crosstalk between Bile Acids and Gut Microbiota and Its Impact on Farnesoid X Receptor Signalling

    Wahlström, Annika; Kovatcheva-Datchary, Petia; Ståhlman, Marcus

    2017-01-01

    Background: The gut microbiota has a substantial impact on health and disease. The human gut microbiota influences the development and progression of metabolic diseases; however, the underlying mechanisms are not fully understood. The nuclear farnesoid X receptor (FXR), which regulates bile acid...... homeostasis and glucose and lipid metabolism, is activated by primary human and murine bile acids, chenodeoxycholic acid and cholic acid, while rodent specific primary bile acids tauromuricholic acids antagonise FXR activation. The gut microbiota deconjugates and subsequently metabolises primary bile acids...... into secondary bile acids in the gut and thereby changes FXR activation and signalling. Key Message: Mouse models have been used to study the crosstalk between bile acids and the gut microbiota, but the substantial differences in bile acid composition between humans and mice need to be considered when...

  1. Attenuation of the jasmonate burst, plant defensive traits, and resistance to specialist monarch caterpillars on shaded common milkweed (Asclepias syriaca).

    Agrawal, Anurag A; Kearney, Emily E; Hastings, Amy P; Ramsey, Trey E

    2012-07-01

    Plant responses to herbivory and light competition are often in opposing directions, posing a potential conflict for plants experiencing both stresses. For sun-adapted species, growing in shade typically makes plants more constitutively susceptible to herbivores via reduced structural and chemical resistance traits. Nonetheless, the impact of light environment on induced resistance has been less well-studied, especially in field experiments that link physiological mechanisms to ecological outcomes. Accordingly, we studied induced resistance of common milkweed (Asclepias syriaca, a sun-adapted plant), and linked hormonal responses, resistance traits, and performance of specialist monarch caterpillars (Danaus plexippus) in varying light environments. In natural populations, plants growing under forest-edge shade showed reduced levels of resistance traits (lower leaf toughness, cardenolides, and trichomes) and enhanced light-capture traits (higher specific leaf area, larger leaves, and lower carbon-to-nitrogen ratio) compared to paired plants in full sun. In a field experiment repeated over two years, only milkweeds growing in full sun exhibited induced resistance to monarchs, whereas plants growing in shade were constitutively more susceptible and did not induce resistance. In a more controlled field experiment, plant hormones were higher in the sun (jasmonic acid, salicylic acid, abscisic acid, indole acidic acid) and were induced by herbivory (jasmonic acid and abscisic acid). In particular, the jasmonate burst following herbivory was halved in plants raised in shaded habitats, and this correspondingly reduced latex induction (but not cardenolide induction). Thus, we provide a mechanistic basis for the attenuation of induced plant resistance in low resource environments. Additionally, there appears to be specificity in these interactions, with light-mediated impacts on jasmonate-induction being stronger for latex exudation than cardenolides.

  2. Interaction between sugar and abscisic acid signalling during early seedling development in Arabidopsis

    Dekkers, B.J.W.; Schuurmans, J.A.M.J.; Smeekens, J.C.M.

    2008-01-01

    Sugars regulate important processes and affect the expression of many genes in plants. Characterization of Arabidopsis (Arabidopsis thaliana) mutants with altered sugar sensitivity revealed the function of abscisic acid (ABA) signalling in sugar responses. However, the exact interaction between

  3. Distinct roles of jasmonates and aldehydes in plant-defense responses.

    E Wassim Chehab

    Full Text Available BACKGROUND: Many inducible plant-defense responses are activated by jasmonates (JAs, C(6-aldehydes, and their corresponding derivatives, produced by the two main competing branches of the oxylipin pathway, the allene oxide synthase (AOS and hydroperoxide lyase (HPL branches, respectively. In addition to competition for substrates, these branch-pathway-derived metabolites have substantial overlap in regulation of gene expression. Past experiments to define the role of C(6-aldehydes in plant defense responses were biased towards the exogenous application of the synthetic metabolites or the use of genetic manipulation of HPL expression levels in plant genotypes with intact ability to produce the competing AOS-derived metabolites. To uncouple the roles of the C(6-aldehydes and jasmonates in mediating direct and indirect plant-defense responses, we generated Arabidopsis genotypes lacking either one or both of these metabolites. These genotypes were subsequently challenged with a phloem-feeding insect (aphids: Myzus persicae, an insect herbivore (leafminers: Liriomyza trifolii, and two different necrotrophic fungal pathogens (Botrytis cinerea and Alternaria brassicicola. We also characterized the volatiles emitted by these plants upon aphid infestation or mechanical wounding and identified hexenyl acetate as the predominant compound in these volatile blends. Subsequently, we examined the signaling role of this compound in attracting the parasitoid wasp (Aphidius colemani, a natural enemy of aphids. PRINCIPAL FINDINGS: This study conclusively establishes that jasmonates and C(6-aldehydes play distinct roles in plant defense responses. The jasmonates are indispensable metabolites in mediating the activation of direct plant-defense responses, whereas the C(6-aldehyes are not. On the other hand, hexenyl acetate, an acetylated C(6-aldehyde, is the predominant wound-inducible volatile signal that mediates indirect defense responses by directing tritrophic

  4. Guard Cell Signal Transduction Network: Advances in Understanding Abscisic Acid, CO2, and Ca2+ Signaling

    Kim, Tae-Houn

    2010-05-04

    Stomatal pores are formed by pairs of specialized epidermal guard cells and serve as major gateways for both CO2 influx into plants from the atmosphere and transpirational water loss of plants. Because they regulate stomatal pore apertures via integration of both endogenous hormonal stimuli and environmental signals, guard cells have been highly developed as a model system to dissect the dynamics and mechanisms of plant-cell signaling. The stress hormone ABA and elevated levels of CO2 activate complex signaling pathways in guard cells that are mediated by kinases/phosphatases, secondary messengers, and ion channel regulation. Recent research in guard cells has led to a new hypothesis for how plants achieve specificity in intracellular calcium signaling: CO2 and ABA enhance (prime) the calcium sensitivity of downstream calcium-signaling mechanisms. Recent progress in identification of early stomatal signaling components are reviewed here, including ABA receptors and CO2-binding response proteins, as well as systems approaches that advance our understanding of guard cell-signaling mechanisms.

  5. Guard Cell Signal Transduction Network: Advances in Understanding Abscisic Acid, CO2, and Ca2+ Signaling

    Kim, Tae-Houn; Bö hmer, Maik; Hu, Honghong; Nishimura, Noriyuki; Schroeder, Julian I.

    2010-01-01

    Stomatal pores are formed by pairs of specialized epidermal guard cells and serve as major gateways for both CO2 influx into plants from the atmosphere and transpirational water loss of plants. Because they regulate stomatal pore apertures via integration of both endogenous hormonal stimuli and environmental signals, guard cells have been highly developed as a model system to dissect the dynamics and mechanisms of plant-cell signaling. The stress hormone ABA and elevated levels of CO2 activate complex signaling pathways in guard cells that are mediated by kinases/phosphatases, secondary messengers, and ion channel regulation. Recent research in guard cells has led to a new hypothesis for how plants achieve specificity in intracellular calcium signaling: CO2 and ABA enhance (prime) the calcium sensitivity of downstream calcium-signaling mechanisms. Recent progress in identification of early stomatal signaling components are reviewed here, including ABA receptors and CO2-binding response proteins, as well as systems approaches that advance our understanding of guard cell-signaling mechanisms.

  6. Transcriptional Responses and Gentiopicroside Biosynthesis in Methyl Jasmonate-Treated Gentiana macrophylla Seedlings.

    Xiaoyan Cao

    Full Text Available Gentiana macrophylla, a medicinal plant with significant pharmacological properties, contains the bioactive compound gentiopicroside. Methyl jasmonate (MeJA is an effective elicitor for enhancing the production of such compounds. However, little is known about MeJA-mediated biosynthesis of gentiopicroside. We investigated this phenomenon as well as gene expression profiles to determine the molecular mechanisms for MeJA-mediated gentiopicroside biosynthesis and regulation in G. macrophylla. Our HPLC results showed that Gentiana macrophylla seedlings exposed to MeJA had significantly higher concentrations of gentiopicroside when compared with control plants. We used RNA sequencing to compare transcriptional profiles in seedlings treated for 5 d with either 0 μmol L-1 MeJA (C or 250 μmol L-1 MeJA (M5 and detected differentially expressed genes (DEGs. In total, 77,482 unique sequences were obtained from approximately 34 million reads. Of these, 48,466 (57.46% sequences were annotated based on BLASTs performed against public databases. We identified 5,206 DEGs between the C and M5 samples, including genes related to the α-lenolenic acid degradation pathway, JA signaling pathway, and gentiopicroside biosynthesis. Expression of numerous enzyme genes in the glycolysis pathway was significantly up-regulated. Many genes encoding transcription factors (e.g. ERF, bHLH, MYB, and WRKY also responded to MeJA elicitation. Rapid acceleration of the glycolysis pathway that supplies precursors for IPP biosynthesis and up-regulates the expression of enzyme genes in that IPP pathway are probably most responsible for MeJA stimulation of gentiopicroside synthesis. Our qRT-PCR results showed that the expression profiles of 12 gentiopicroside biosynthesis genes were consistent with the RNA-Seq data. These results increase our understanding about how the gentiopicroside biosynthesis pathway in G. macrophylla responds to MeJA.

  7. Amino acid metabolic signaling influences Aedes aegypti midgut microbiome variability.

    Sarah M Short

    2017-07-01

    Full Text Available The mosquito midgut microbiota has been shown to influence vector competence for multiple human pathogens. The microbiota is highly variable in the field, and the sources of this variability are not well understood, which limits our ability to understand or predict its effects on pathogen transmission. In this work, we report significant variation in female adult midgut bacterial load between strains of A. aegypti which vary in their susceptibility to dengue virus. Composition of the midgut microbiome was similar overall between the strains, with 81-92% of reads coming from the same five bacterial families, though we did detect differences in the presence of some bacterial families including Flavobacteriaceae and Entobacteriaceae. We conducted transcriptomic analysis on the two mosquito strains that showed the greatest difference in bacterial load, and found that they differ in transcript abundance of many genes implicated in amino acid metabolism, in particular the branched chain amino acid degradation pathway. We then silenced this pathway by targeting multiple genes using RNA interference, which resulted in strain-specific bacterial proliferation, thereby eliminating the difference in midgut bacterial load between the strains. This suggests that the branched chain amino acid (BCAA degradation pathway controls midgut bacterial load, though the mechanism underlying this remains unclear. Overall, our results indicate that amino acid metabolism can act to influence the midgut microbiota. Moreover, they suggest that genetic or physiological variation in BCAA degradation pathway activity may in part explain midgut microbiota variation in the field.

  8. Afferent signalling from the acid-challenged rat stomach is inhibited and gastric acid elimination is enhanced by lafutidine

    Holzer Peter

    2009-06-01

    Full Text Available Abstract Background Lafutidine is a histamine H2 receptor antagonist, the gastroprotective effect of which is related to its antisecretory activity and its ability to activate a sensory neuron-dependent mechanism of defence. The present study investigated whether intragastric administration of lafutidine (10 and 30 mg/kg modifies vagal afferent signalling, mucosal injury, intragastric acidity and gastric emptying after gastric acid challenge. Methods Adult rats were treated with vehicle, lafutidine (10 – 30 mg/kg or cimetidine (10 mg/kg, and 30 min later their stomachs were exposed to exogenous HCl (0.25 M. During the period of 2 h post-HCl, intragastric pH, gastric volume, gastric acidity and extent of macroscopic gastric mucosal injury were determined and the activation of neurons in the brainstem was visualized by c-Fos immunocytochemistry. Results Gastric acid challenge enhanced the expression of c-Fos in the nucleus tractus solitarii but caused only minimal damage to the gastric mucosa. Lafutidine reduced the HCl-evoked expression of c-Fos in the NTS and elevated the intragastric pH following intragastric administration of excess HCl. Further analysis showed that the gastroprotective effect of lafutidine against excess acid was delayed and went in parallel with facilitation of gastric emptying, measured indirectly via gastric volume changes, and a reduction of gastric acidity. The H2 receptor antagonist cimetidine had similar but weaker effects. Conclusion These observations indicate that lafutidine inhibits the vagal afferent signalling of a gastric acid insult, which may reflect an inhibitory action on acid-induced gastric pain. The ability of lafutidine to decrease intragastric acidity following exposure to excess HCl cannot be explained by its antisecretory activity but appears to reflect dilution and/or emptying of the acid load into the duodenum. This profile of actions emphasizes the notion that H2 receptor antagonists can protect

  9. Folic Acid supplementation stimulates notch signaling and cell proliferation in embryonic neural stem cells.

    Liu, Huan; Huang, Guo-Wei; Zhang, Xu-Mei; Ren, Da-Lin; X Wilson, John

    2010-09-01

    The present study investigated the effect of folic acid supplementation on the Notch signaling pathway and cell proliferation in rat embryonic neural stem cells (NSCs). The NSCs were isolated from E14-16 rat brain and grown as neurospheres in serum-free suspension culture. Individual cultures were assigned to one of 3 treatment groups that differed according to the concentration of folic acid in the medium: Control (baseline folic acid concentration of 4 mg/l), low folic acid supplementation (4 mg/l above baseline, Folate-L) and high folic acid supplementation (40 mg/l above baseline, Folate-H). NSCs were identified by their expression of immunoreactive nestin and proliferating cells by incorporation of 5'bromo-2'deoxyuridine. Cell proliferation was also assessed by methyl thiazolyl tetrazolium assay. Notch signaling was analyzed by real-time PCR and western blot analyses of the expression of Notch1 and hairy and enhancer of split 5 (Hes5). Supplementation of NSCs with folic acid increased the mRNA and protein expression levels of Notch1 and Hes5. Folic acid supplementation also stimulated NSC proliferation dose-dependently. Embryonic NSCs respond to folic acid supplementation with increased Notch signaling and cell proliferation. This mechanism may mediate the effects of folic acid supplementation on neurogenesis in the embryonic nervous system.

  10. Jasmonate-induced biosynthesis of andrographolide in Andrographis paniculata.

    Sharma, Shiv Narayan; Jha, Zenu; Sinha, Rakesh Kumar; Geda, Arvind Kumar

    2015-02-01

    Andrographolide is a prominent secondary metabolite found in Andrographis paniculata that exhibits enormous pharmacological effects. In spite of immense value, the normal biosynthesis of andrographolide results in low amount of the metabolite. To induce the biosynthesis of andrographolide, we attempted elicitor-induced activation of andrographolide biosynthesis in cell cultures of A. paniculata. This was carried out by using methyl jasmonate (MeJA) as an elicitor. Among the various concentrations of MeJA tested at different time periods, 5 µM MeJA yielded 5.25 times more andrographolide content after 24 h of treatment. The accumulation of andrographolide was correlated with the expression level of known regulatory genes (hmgs, hmgr, dxs, dxr, isph and ggps) of mevalonic acid (MVA) and 2-C-methyl-d-erythritol-4-phosphate (MEP) pathways. These results established the involvement of MeJA in andrographolide biosynthesis by inducing the transcription of its biosynthetic pathways genes. The coordination of isph, ggps and hmgs expression highly influenced the andrographolide biosynthesis. © 2014 Scandinavian Plant Physiology Society.

  11. Retinoic acid is a potential dorsalising signal in the late embryonic chick hindbrain

    Maden Malcolm

    2007-12-01

    Full Text Available Abstract Background Human retinoic acid teratogenesis results in malformations of dorsally derived hindbrain structures such as the cerebellum, noradrenergic hindbrain neurons and the precerebellar system. These structures originate from the rhombic lip and adjacent dorsal precursor pools that border the fourth ventricle roofplate. While retinoic acid synthesis is known to occur in the meninges that blanket the hindbrain, the particular sensitivity of only dorsal structures to disruptions in retinoid signalling is puzzling. We therefore looked for evidence within the neural tube for more spatiotemporally specific signalling pathways using an in situ hybridisation screen of known retinoic acid pathway transcripts. Results We find that there are highly restricted domains of retinoic acid synthesis and breakdown within specific hindbrain nuclei as well as the ventricular layer and roofplate. Intriguingly, transcripts of cellular retinoic acid binding protein 1 are always found at the interface between dividing and post-mitotic cells. By contrast to earlier stages of development, domains of synthesis and breakdown in post-mitotic neurons are co-localised. At the rhombic lip, expression of the mRNA for retinoic acid synthesising and catabolising enzymes is spatially highly organised with respect to the Cath1-positive precursors of migratory precerebellar neurons. Conclusion The late developing hindbrain shows patterns of retinoic acid synthesis and use that are distinct from the well characterised phase of rostrocaudal patterning. Selected post-mitotic populations, such as the locus coeruleus, appear to both make and break down retinoic acid suggesting that a requirement for an autocrine, or at least a highly localised paracrine signalling network, might explain its acute sensitivity to retinoic acid disruption. At the rhombic lip, retinoic acid is likely to act as a dorsalising factor in parallel with other roofplate signalling pathways. While its

  12. Identification of Palmitoleic Acid Controlled by mTOR Signaling as a Biomarker of Polymyositis

    Geng Yin

    2017-01-01

    Full Text Available Polymyositis (PM is a chronic disease characterized by muscle pain, weakness, and increase in muscle-related enzymes, accompanied with inflammations in lymphocytes. However, it is not well understood how the molecular alternations in lymphocytes contribute to the development of polymyositis. The mechanistic target of rapamycin (mTOR signaling is the central regulator of metabolism and inflammation in mammalian cells. Based on previous studies, we proposed that mTOR signaling may control inflammatory reactions via lipid metabolism. In this study, we aim to figure out the role of mTOR signaling in the development of polymyositis and identify novel biomarkers for the detection and therapy of polymyositis. After screening and validation, we found that palmitoleic acid, a monounsaturated fatty acid, is highly regulated by mTOR signaling. Inhibition of mTORC1 activity decreases palmitoleic acid level. Moreover, mTORC1 regulates the level of palmitoleic acid by controlling its de novo synthesis. Importantly, increased palmitoleic acid has been proven to be a marker of polymyositis. Our work identifies palmitoleic acid in peripheral blood mononuclear cells (PBMC as a biomarker of polymyositis and offers new targets to the clinical therapy.

  13. The ABA-INSENSITIVE-4 (ABI4) transcription factor links redox, hormone and sugar signaling pathways.

    Foyer, Christine H; Kerchev, Pavel I; Hancock, Robert D

    2012-02-01

    The cellular reduction-oxidation (redox) hub processes information from metabolism and the environment and so regulates plant growth and defense through integration with the hormone signaling network. One key pathway of redox control involves interactions with ABSCISIC ACID (ABA). Accumulating evidence suggests that the ABA-INSENSITIVE-4 (ABI4) transcription factor plays a key role in transmitting information concerning the abundance of ascorbate and hence the ability of cells to buffer oxidative challenges. ABI4 is required for the ascorbate-dependent control of growth, a process that involves enhancement of salicylic acid (SA) signaling and inhibition of jasmonic acid (JA) signaling pathways. Low redox buffering capacity reinforces SA- JA- interactions through the mediation of ABA and ABI4 to fine-tune plant growth and defense in relation to metabolic cues and environmental challenges. Moreover, ABI4-mediated pathways of sugar sensitivity are also responsive to the abundance of ascorbate, providing evidence of overlap between redox and sugar signaling pathways.

  14. Regulation of autophagy by amino acids and MTOR-dependent signal transduction.

    Meijer, Alfred J; Lorin, Séverine; Blommaart, Edward F; Codogno, Patrice

    2015-10-01

    Amino acids not only participate in intermediary metabolism but also stimulate insulin-mechanistic target of rapamycin (MTOR)-mediated signal transduction which controls the major metabolic pathways. Among these is the pathway of autophagy which takes care of the degradation of long-lived proteins and of the elimination of damaged or functionally redundant organelles. Proper functioning of this process is essential for cell survival. Dysregulation of autophagy has been implicated in the etiology of several pathologies. The history of the studies on the interrelationship between amino acids, MTOR signaling and autophagy is the subject of this review. The mechanisms responsible for the stimulation of MTOR-mediated signaling, and the inhibition of autophagy, by amino acids have been studied intensively in the past but are still not completely clarified. Recent developments in this field are discussed.

  15. Drosophila fatty acid taste signals through the PLC pathway in sugar-sensing neurons.

    Pavel Masek

    Full Text Available Taste is the primary sensory system for detecting food quality and palatability. Drosophila detects five distinct taste modalities that include sweet, bitter, salt, water, and the taste of carbonation. Of these, sweet-sensing neurons appear to have utility for the detection of nutritionally rich food while bitter-sensing neurons signal toxicity and confer repulsion. Growing evidence in mammals suggests that taste for fatty acids (FAs signals the presence of dietary lipids and promotes feeding. While flies appear to be attracted to fatty acids, the neural basis for fatty acid detection and attraction are unclear. Here, we demonstrate that a range of FAs are detected by the fly gustatory system and elicit a robust feeding response. Flies lacking olfactory organs respond robustly to FAs, confirming that FA attraction is mediated through the gustatory system. Furthermore, flies detect FAs independent of pH, suggesting the molecular basis for FA taste is not due to acidity. We show that low and medium concentrations of FAs serve as an appetitive signal and they are detected exclusively through the same subset of neurons that sense appetitive sweet substances, including most sugars. In mammals, taste perception of sweet and bitter substances is dependent on phospholipase C (PLC signaling in specialized taste buds. We find that flies mutant for norpA, a Drosophila ortholog of PLC, fail to respond to FAs. Intriguingly, norpA mutants respond normally to other tastants, including sucrose and yeast. The defect of norpA mutants can be rescued by selectively restoring norpA expression in sweet-sensing neurons, corroborating that FAs signal through sweet-sensing neurons, and suggesting PLC signaling in the gustatory system is specifically involved in FA taste. Taken together, these findings reveal that PLC function in Drosophila sweet-sensing neurons is a conserved molecular signaling pathway that confers attraction to fatty acids.

  16. The chemical foundations of nitroalkene fatty acid signaling through addition reactions with thiols.

    Turell, Lucía; Steglich, Martina; Alvarez, Beatriz

    2018-03-22

    Nitroalkene fatty acids can be formed in vivo and administered exogenously. They exert pleiotropic signaling actions with cytoprotective and antiinflammatory effects. The presence of the potent electron withdrawing nitro group confers electrophilicity to the adjacent β-carbon. Thiols (precisely, thiolates) are strong nucleophiles and can react with nitroalkene fatty acids through reversible Michael addition reactions. In addition, nitroalkene fatty acids can undergo several other processes including metabolic oxidation, reduction, esterification, nitric oxide release and partition into hydrophobic compartments. The signaling actions of nitroalkenes are mainly mediated by reactions with critical thiols in regulatory proteins. Thus, the thio-Michael addition reaction provides a framework for understanding the molecular basis of the biological effects of nitroalkene fatty acids at the crossroads of thiol signaling and electrophilic lipid signaling. In this review, we describe the reactions of nitroalkene fatty acids in biological contexts. We focus on the Michael addition-elimination reaction with thiols and its mechanism, and extrapolate kinetic and thermodynamic considerations to in vivo settings. Copyright © 2018 Elsevier Inc. All rights reserved.

  17. Individual bile acids have differential effects on bile acid signaling in mice

    Song, Peizhen; Rockwell, Cheryl E.; Cui, Julia Yue; Klaassen, Curtis D.

    2015-01-01

    Bile acids (BAs) are known to regulate BA synthesis and transport by the farnesoid X receptor in the liver (FXR-SHP) and intestine (FXR-Fgf15). However, the relative importance of individual BAs in regulating these processes is not known. Therefore, mice were fed various doses of five individual BAs, including cholic acid (CA), chenodeoxycholic acid (CDCA), deoxoycholic acid (DCA), lithocholic acid (LCA), and ursodeoxycholic acid (UDCA) in their diets at various concentrations for one week to increase the concentration of one BA in the enterohepatic circulation. The mRNA of BA synthesis and transporting genes in liver and ileum were quantified. In the liver, the mRNA of SHP, which is the prototypical target gene of FXR, increased in mice fed all concentrations of BAs. In the ileum, the mRNA of the intestinal FXR target gene Fgf15 was increased at lower doses and to a higher extent by CA and DCA than by CDCA and LCA. Cyp7a1, the rate-limiting enzyme in BA synthesis, was decreased more by CA and DCA than CDCA and LCA. Cyp8b1, the enzyme that 12-hydroxylates BAs and is thus responsible for the synthesis of CA, was decreased much more by CA and DCA than CDCA and LCA. Surprisingly, neither a decrease in the conjugated BA uptake transporter (Ntcp) nor increase in BA efflux transporter (Bsep) was observed by FXR activation, but an increase in the cholesterol efflux transporter (Abcg5/Abcg8) was observed with FXR activation. Thus in conclusion, CA and DCA are more potent FXR activators than CDCA and LCA when fed to mice, and thus they are more effective in decreasing the expression of the rate limiting gene in BA synthesis Cyp7a1 and the 12-hydroxylation of BAs Cyp8b1, and are also more effective in increasing the expression of Abcg5/Abcg8, which is responsible for biliary cholesterol excretion. However, feeding BAs do not alter the mRNA or protein levels of Ntcp or Bsep, suggesting that the uptake or efflux of BAs is not regulated by FXR at physiological and

  18. Individual bile acids have differential effects on bile acid signaling in mice

    Song, Peizhen, E-mail: songacad@gmail.com; Rockwell, Cheryl E., E-mail: rockwelc@msu.edu; Cui, Julia Yue, E-mail: juliacui@uw.edu; Klaassen, Curtis D., E-mail: curtisklaassenphd@gmail.com

    2015-02-15

    Bile acids (BAs) are known to regulate BA synthesis and transport by the farnesoid X receptor in the liver (FXR-SHP) and intestine (FXR-Fgf15). However, the relative importance of individual BAs in regulating these processes is not known. Therefore, mice were fed various doses of five individual BAs, including cholic acid (CA), chenodeoxycholic acid (CDCA), deoxoycholic acid (DCA), lithocholic acid (LCA), and ursodeoxycholic acid (UDCA) in their diets at various concentrations for one week to increase the concentration of one BA in the enterohepatic circulation. The mRNA of BA synthesis and transporting genes in liver and ileum were quantified. In the liver, the mRNA of SHP, which is the prototypical target gene of FXR, increased in mice fed all concentrations of BAs. In the ileum, the mRNA of the intestinal FXR target gene Fgf15 was increased at lower doses and to a higher extent by CA and DCA than by CDCA and LCA. Cyp7a1, the rate-limiting enzyme in BA synthesis, was decreased more by CA and DCA than CDCA and LCA. Cyp8b1, the enzyme that 12-hydroxylates BAs and is thus responsible for the synthesis of CA, was decreased much more by CA and DCA than CDCA and LCA. Surprisingly, neither a decrease in the conjugated BA uptake transporter (Ntcp) nor increase in BA efflux transporter (Bsep) was observed by FXR activation, but an increase in the cholesterol efflux transporter (Abcg5/Abcg8) was observed with FXR activation. Thus in conclusion, CA and DCA are more potent FXR activators than CDCA and LCA when fed to mice, and thus they are more effective in decreasing the expression of the rate limiting gene in BA synthesis Cyp7a1 and the 12-hydroxylation of BAs Cyp8b1, and are also more effective in increasing the expression of Abcg5/Abcg8, which is responsible for biliary cholesterol excretion. However, feeding BAs do not alter the mRNA or protein levels of Ntcp or Bsep, suggesting that the uptake or efflux of BAs is not regulated by FXR at physiological and

  19. 12-oxo-phytodienoic acid, a plant-derived oxylipin, attenuates lipopolysaccharide-induced inflammation in microglia

    Taki-Nakano, Nozomi [Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259-B-65 Nagatsuta-cho, Midori-ku, Yokohama 226-8501 (Japan); Advanced Drug Research Laboratories, Sohyaku. Innovative Research Division, Mitsubishi Tanabe Pharma Corporation, 2-2-50, Kawagishi, Toda, Saitama 335-8505 (Japan); Kotera, Jun [Advanced Drug Research Laboratories, Sohyaku. Innovative Research Division, Mitsubishi Tanabe Pharma Corporation, 2-2-50, Kawagishi, Toda, Saitama 335-8505 (Japan); Ohta, Hiroyuki, E-mail: ohta.h.ab@m.titech.ac.jp [Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259-B-65 Nagatsuta-cho, Midori-ku, Yokohama 226-8501 (Japan); School of Life Science and Technology, Tokyo Institute of Technology, 4259-B-65 Nagatsuta-cho, Midori-ku, Yokohama 226-8501 (Japan)

    2016-05-13

    Jasmonates are plant lipid–derived oxylipins that act as key signaling compounds in plant immunity, germination, and development. Although some physiological activities of natural jasmonates in mammalian cells have been investigated, their anti-inflammatory actions in mammalian cells remain unclear. Here, we investigated whether jasmonates protect mouse microglial MG5 cells against lipopolysaccharide (LPS)–induced inflammation. Among the jasmonates tested, only 12-oxo-phytodienoic acid (OPDA) suppressed LPS-induced expression of the typical inflammatory cytokines interleukin-6 and tumor necrosis factor α. In addition, only OPDA reduced LPS-induced nitric oxide production through a decrease in the level of inducible nitric oxide synthase. Further mechanistic studies showed that OPDA suppressed neuroinflammation by inhibiting nuclear factor κB and p38 mitogen-activated protein kinase signaling in LPS-activated MG5 cells. In addition, OPDA induced expression of suppressor of cytokine signaling-1 (SOCS-1), a negative regulator of inflammation, in MG5 cells. Finally, we found that the nuclear factor erythroid 2-related factor 2 signaling cascade induced by OPDA is not involved in the anti-inflammatory effects of OPDA. These results demonstrate that OPDA inhibited LPS-induced cell inflammation in mouse microglial cells via multiple pathways, including suppression of nuclear factor κB, inhibition of p38, and activation of SOCS-1 signaling. -- Highlights: •OPDA attenuates LPS-induced inflammatory cytokines such as IL-6 and TNF-α. •OPDA reduces LPS-induced iNOS expression and NO production. •OPDA suppresses NF-κB and p38 pathways and activates SOCS-1 signaling.

  20. 12-oxo-phytodienoic acid, a plant-derived oxylipin, attenuates lipopolysaccharide-induced inflammation in microglia

    Taki-Nakano, Nozomi; Kotera, Jun; Ohta, Hiroyuki

    2016-01-01

    Jasmonates are plant lipid–derived oxylipins that act as key signaling compounds in plant immunity, germination, and development. Although some physiological activities of natural jasmonates in mammalian cells have been investigated, their anti-inflammatory actions in mammalian cells remain unclear. Here, we investigated whether jasmonates protect mouse microglial MG5 cells against lipopolysaccharide (LPS)–induced inflammation. Among the jasmonates tested, only 12-oxo-phytodienoic acid (OPDA) suppressed LPS-induced expression of the typical inflammatory cytokines interleukin-6 and tumor necrosis factor α. In addition, only OPDA reduced LPS-induced nitric oxide production through a decrease in the level of inducible nitric oxide synthase. Further mechanistic studies showed that OPDA suppressed neuroinflammation by inhibiting nuclear factor κB and p38 mitogen-activated protein kinase signaling in LPS-activated MG5 cells. In addition, OPDA induced expression of suppressor of cytokine signaling-1 (SOCS-1), a negative regulator of inflammation, in MG5 cells. Finally, we found that the nuclear factor erythroid 2-related factor 2 signaling cascade induced by OPDA is not involved in the anti-inflammatory effects of OPDA. These results demonstrate that OPDA inhibited LPS-induced cell inflammation in mouse microglial cells via multiple pathways, including suppression of nuclear factor κB, inhibition of p38, and activation of SOCS-1 signaling. -- Highlights: •OPDA attenuates LPS-induced inflammatory cytokines such as IL-6 and TNF-α. •OPDA reduces LPS-induced iNOS expression and NO production. •OPDA suppresses NF-κB and p38 pathways and activates SOCS-1 signaling.

  1. Key mediators of intracellular amino acids signaling to mTORC1 activation.

    Duan, Yehui; Li, Fengna; Tan, Kunrong; Liu, Hongnan; Li, Yinghui; Liu, Yingying; Kong, Xiangfeng; Tang, Yulong; Wu, Guoyao; Yin, Yulong

    2015-05-01

    Mammalian target of rapamycin complex 1 (mTORC1) is activated by amino acids to promote cell growth via protein synthesis. Specifically, Ras-related guanosine triphosphatases (Rag GTPases) are activated by amino acids, and then translocate mTORC1 to the surface of late endosomes and lysosomes. Ras homolog enriched in brain (Rheb) resides on this surface and directly activates mTORC1. Apart from the presence of intracellular amino acids, Rag GTPases and Rheb, other mediators involved in intracellular amino acid signaling to mTORC1 activation include human vacuolar sorting protein-34 (hVps34) and mitogen-activating protein kinase kinase kinase kinase-3 (MAP4K3). Those molecular links between mTORC1 and its mediators form a complicate signaling network that controls cellular growth, proliferation, and metabolism. Moreover, it is speculated that amino acid signaling to mTORC1 may start from the lysosomal lumen. In this review, we discussed the function of these mediators in mTORC1 pathway and how these mediators are regulated by amino acids in details.

  2. Wnt/β-catenin signalling pathway mediated aberrant hippocampal neurogenesis in kainic acid-induced epilepsy.

    Qu, Zhengyi; Su, Fang; Qi, Xueting; Sun, Jianbo; Wang, Hongcai; Qiao, Zhenkui; Zhao, Hong; Zhu, Yulan

    2017-10-01

    Temporal lobe epilepsy is a chronic disorder of nerve system, mainly characterized by hippocampal sclerosis with massive neuronal loss and severe gliosis. Aberrant neurogenesis has been shown in the epileptogenesis process of temporal lobe epilepsy. However, the molecular mechanisms underlying aberrant neurogenesis remain unclear. The roles of Wnt signalling cascade have been well established in neurogenesis during multiple aspects. Here, we used kainic acid-induced rat epilepsy model to investigate whether Wnt/β-catenin signalling pathway is involved in the aberrant neurogenesis in temporal lobe epilepsy. Immunostaining and western blotting results showed that the expression levels of β-catenin, Wnt3a, and cyclin D1, the key regulators in Wnt signalling pathway, were up-regulated during acute epilepsy induced by the injection of kainic acids, indicating that Wnt signalling pathway was activated in kainic acid-induced temporal lobe epilepsy. Moreover, BrdU labelling results showed that blockade of the Wnt signalling by knocking down β-catenin attenuated aberrant neurogenesis induced by kainic acids injection. Altogether, Wnt/β-catenin signalling pathway mediated hippocampal neurogenesis during epilepsy, which might provide new strategies for clinical treatment of temporal lobe epilepsy. Temporal lobe epilepsy is a chronic disorder of nerve system, mainly characterized by hippocampal sclerosis. Aberrant neurogenesis has been shown to involve in the epileptogenesis process of temporal lobe epilepsy. In the present study, we discovered that Wnt3a/β-catenin signalling pathway serves as a link between aberrant neurogenesis and underlying remodelling in the hippocampus, leading to temporal lobe epilepsy, which might provide new strategies for clinical treatment of temporal lobe epilepsy. Copyright © 2017 John Wiley & Sons, Ltd.

  3. Induction of a leaf specific geranylgeranyl pyrophosphate synthase and emission of (E,E)-4,8,12-trimethyltrideca-1,3,7,11-tetraene in tomato are dependent on both jasmonic acid and salicylic acid signaling pathways

    Ament, K.; Schie, C.C.; Bouwmeester, H.J.; Haring, M.A.; Schuurink, R.C.

    2006-01-01

    Two cDNAs encoding geranylgeranyl pyrophosphate (GGPP) synthases from tomato (Lycopersicon esculentum) have been cloned and functionally expressed in Escherichia coli. LeGGPS1 was predominantly expressed in leaf tissue and LeGGPS2 in ripening fruit and flower tissue. LeGGPS1 expression was induced

  4. Mechanisms of amino acid sensing in mTOR signaling pathway

    Kim, Eunjung

    2009-01-01

    Amino acids are fundamental nutrients for protein synthesis and cell growth (increase in cell size). Recently, many compelling evidences have shown that the level of amino acids is sensed by extra- or intra-cellular amino acids sensor(s) and regulates protein synthesis/degradation. Mammalian target of rapamycin complex 1 (mTORC1) is placed in a central position in cell growth regulation and dysregulation of mTOR signaling pathway has been implicated in many serious human diseases including ca...

  5. Cold stress improves the production of artemisinin depending on the increase in endogenous jasmonate.

    Liu, Wanhong; Wang, Huanyan; Chen, Yupei; Zhu, Shunqin; Chen, Min; Lan, Xiaozhong; Chen, Guoping; Liao, Zhihua

    2017-05-01

    Previous publications reported that the artemisinin level was increased in Artemisia annua following a night-frost period. However, the molecular mechanism was not clear. In this study, we found that exogenous jasmonate (JA) effectively enhanced the freezing tolerance of A. annua. The JA biosynthetic genes (LOX1, LOX2, allene oxide cyclase [AOC], and jasmonate resistant 1 [JAR1]) were induced by cold stress, leading to an increase in endogenous JA in cold-treated A. annua. Increased endogenous JA enhanced the expression of three JA-responsive transcription factors, ethylene response factor 1, ethylene response factor 2, and octadecanoid-responsive AP2/ERF, all of which were reported to transcriptionally activate the expression of artemisinin biosynthetic genes, such as amorpha-4,11-diene synthase (ADS), CYP71AV1, DBR2, and aldehyde dehydrogenase 1 (ALDH1). Furthermore, the expression levels of the four artemisinin biosynthetic genes were also significantly increased under cold stress. Consequently, the levels of artemisinin and related secondary metabolites, such as dihydroartemisinic acid, artemisinin B, and artemisinic acid, were increased in A. annua under cold stress. Our study points to a molecular mechanism in which the production of artemisinin is regulated by cold stress in A. annua. © 2016 International Union of Biochemistry and Molecular Biology, Inc.

  6. Branched-chain amino acids in metabolic signaling and insulin resistance

    Branched-chain amino acids (BCAAs) are important directly- and indirectly-acting nutrient signals. Frequently, their actions have been reported to be anti-obesity in nature, especially in rodent models. Yet, circulating BCAAs tend to be elevated in obesity, and even associated with poorer metaboli...

  7. Regulation of autophagy by amino acids and MTOR-dependent signal transduction

    Meijer, Alfred J.; Lorin, Séverine; Blommaart, Edward F.; Codogno, Patrice

    2015-01-01

    Amino acids not only participate in intermediary metabolism but also stimulate insulin-mechanistic target of rapamycin (MTOR)-mediated signal transduction which controls the major metabolic pathways. Among these is the pathway of autophagy which takes care of the degradation of long-lived proteins

  8. Salicylic acid induces vanillin synthesis through the phospholipid signaling pathway in Capsicum chinense cell cultures.

    Rodas-Junco, Beatriz A; Cab-Guillén, Yahaira; Muñoz-Sánchez, J Armando; Vázquez-Flota, Felipe; Monforte-González, Miriam; Hernández-Sotomayor, S M Teresa

    2013-10-01

    Signal transduction via phospholipids is mediated by phospholipases such as phospholipase C (PLC) and D (PLD), which catalyze hydrolysis of plasma membrane structural phospholipids. Phospholipid signaling is also involved in plant responses to phytohormones such as salicylic acid (SA). The relationships between phospholipid signaling, SA, and secondary metabolism are not fully understood. Using a Capsicum chinense cell suspension as a model, we evaluated whether phospholipid signaling modulates SA-induced vanillin production through the activation of phenylalanine ammonia lyase (PAL), a key enzyme in the biosynthetic pathway. Salicylic acid was found to elicit PAL activity and consequently vanillin production, which was diminished or reversed upon exposure to the phosphoinositide-phospholipase C (PI-PLC) signaling inhibitors neomycin and U73122. Exposure to the phosphatidic acid inhibitor 1-butanol altered PLD activity and prevented SA-induced vanillin production. Our results suggest that PLC and PLD-generated secondary messengers may be modulating SA-induced vanillin production through the activation of key biosynthetic pathway enzymes.

  9. NR4A orphan nuclear receptors influence retinoic acid and docosahexaenoic acid signaling via up-regulation of fatty acid binding protein 5

    Volakakis, Nikolaos; Joodmardi, Eliza; Perlmann, Thomas

    2009-01-01

    The orphan nuclear receptor (NR) Nurr1 is expressed in the developing and adult nervous system and is also induced as an immediate early gene in a variety of cell types. In silico analysis of human promoters identified fatty acid binding protein 5 (FABP5), a protein shown to enhance retinoic acid-mediated PPARβ/δ signaling, as a potential Nurr1 target gene. Nurr1 has previously been implicated in retinoid signaling via its heterodimerization partner RXR. Since NRs are commonly involved in cross-regulatory control we decided to further investigate the regulatory relationship between Nurr1 and FABP5. FABP5 expression was up-regulated by Nurr1 and other NR4A NRs in HEK293 cells, and Nurr1 was shown to activate and bind to the FABP5 promoter, supporting that FABP5 is a direct downstream target of NR4A NRs. We also show that the RXR ligand docosahexaenoic acid (DHA) can induce nuclear translocation of FABP5. Moreover, via up-regulation of FABP5 Nurr1 can enhance retinoic acid-induced signaling of PPARβ/δ and DHA-induced activation of RXR. We also found that other members of the NR4A orphan NRs can up-regulate FABP5. Thus, our findings suggest that NR4A orphan NRs can influence signaling events of other NRs via control of FABP5 expression levels.

  10. NR4A orphan nuclear receptors influence retinoic acid and docosahexaenoic acid signaling via up-regulation of fatty acid binding protein 5

    Volakakis, Nikolaos; Joodmardi, Eliza [Ludwig Institute for Cancer Research Ltd., Box 240, S-17177 Stockholm (Sweden); Perlmann, Thomas, E-mail: thomas.perlmann@licr.ki.se [Ludwig Institute for Cancer Research Ltd., Box 240, S-17177 Stockholm (Sweden); The Department of Cell and Molecular Biology, Karolinska Institute, S-17177 Stockholm (Sweden)

    2009-12-25

    The orphan nuclear receptor (NR) Nurr1 is expressed in the developing and adult nervous system and is also induced as an immediate early gene in a variety of cell types. In silico analysis of human promoters identified fatty acid binding protein 5 (FABP5), a protein shown to enhance retinoic acid-mediated PPAR{beta}/{delta} signaling, as a potential Nurr1 target gene. Nurr1 has previously been implicated in retinoid signaling via its heterodimerization partner RXR. Since NRs are commonly involved in cross-regulatory control we decided to further investigate the regulatory relationship between Nurr1 and FABP5. FABP5 expression was up-regulated by Nurr1 and other NR4A NRs in HEK293 cells, and Nurr1 was shown to activate and bind to the FABP5 promoter, supporting that FABP5 is a direct downstream target of NR4A NRs. We also show that the RXR ligand docosahexaenoic acid (DHA) can induce nuclear translocation of FABP5. Moreover, via up-regulation of FABP5 Nurr1 can enhance retinoic acid-induced signaling of PPAR{beta}/{delta} and DHA-induced activation of RXR. We also found that other members of the NR4A orphan NRs can up-regulate FABP5. Thus, our findings suggest that NR4A orphan NRs can influence signaling events of other NRs via control of FABP5 expression levels.

  11. Retinoic acid signaling: a new piece in the spoken language puzzle

    Jon-Ruben eVan Rhijn

    2015-11-01

    Full Text Available Speech requires precise motor control and rapid sequencing of highly complex vocal musculature. Despite its complexity, most people produce spoken language effortlessly. This is due to activity in distributed neuronal circuitry including cortico-striato-thalamic loops that control speech-motor output. Understanding the neuro-genetic mechanisms that encode these pathways will shed light on how humans can effortlessly and innately use spoken language and could elucidate what goes wrong in speech-language disorders.FOXP2 was the first single gene identified to cause speech and language disorder. Individuals with FOXP2 mutations display a severe speech deficit that also includes receptive and expressive language impairments. The underlying neuro-molecular mechanisms controlled by FOXP2, which will give insight into our capacity for speech-motor control, are only beginning to be unraveled. Recently FOXP2 was found to regulate genes involved in retinoic acid signaling and to modify the cellular response to retinoic acid, a key regulator of brain development. Herein we explore the evidence that FOXP2 and retinoic acid signaling function in the same pathways. We present evidence at molecular, cellular and behavioral levels that suggest an interplay between FOXP2 and retinoic acid that may be important for fine motor control and speech-motor output. We propose that retinoic acid signaling is an exciting new angle from which to investigate how neurogenetic mechanisms can contribute to the (spoken language ready brain.

  12. Uric Acid Induces Renal Inflammation via Activating Tubular NF-κB Signaling Pathway

    Zhou, Yang; Fang, Li; Jiang, Lei; Wen, Ping; Cao, Hongdi; He, Weichun; Dai, Chunsun; Yang, Junwei

    2012-01-01

    Inflammation is a pathologic feature of hyperuricemia in clinical settings. However, the underlying mechanism remains unknown. Here, infiltration of T cells and macrophages were significantly increased in hyperuricemia mice kidneys. This infiltration of inflammatory cells was accompanied by an up-regulation of TNF-α, MCP-1 and RANTES expression. Further, infiltration was largely located in tubular interstitial spaces, suggesting a role for tubular cells in hyperuricemia-induced inflammation. In cultured tubular epithelial cells (NRK-52E), uric acid, probably transported via urate transporter, induced TNF-α, MCP-1 and RANTES mRNA as well as RANTES protein expression. Culture media of NRK-52E cells incubated with uric acid showed a chemo-attractive ability to recruit macrophage. Moreover uric acid activated NF-κB signaling. The uric acid-induced up-regulation of RANTES was blocked by SN 50, a specific NF-κB inhibitor. Activation of NF-κB signaling was also observed in tubule of hyperuricemia mice. These results suggest that uric acid induces renal inflammation via activation of NF-κB signaling. PMID:22761883

  13. AI-2 signalling is induced by acidic shock in probiotic strains of Lactobacillus spp

    Moslehi Jenabian, Saloomeh; Gori, Klaus; Jespersen, Lene

    2009-01-01

    Survival and ability to respond to various environmental stresses such as low pH are important factors for lactobacilli for their function as probiotics. LuxS-mediated quorum sensing mechanism, which is based on the production of universal signal molecule called autoinducer-2 (AI-2), regulates...... important physiological traits and a variety of adaptive processes in different bacteria. The aim of this study was to investigate the effect of acidic stress on LuxS-mediated quorum sensing (AI-2 signalling) in four probiotic strains of different Lactobacillus species. Initially, the production of AI-2...... concomitant with the reduction of pH, reaching maximum at late exponential phase (L. rhamnosus GG) or at stationary phase (L. salivarius UCC118, L. acidophilus NCFM and L. johnsonii NCC533). Acidic shock experiments were conducted on L. rhamnosus GG and L. acidophilus NCFM after exposure to different acidic...

  14. Hormonal signaling in plant immunity

    Caarls, L.

    2016-01-01

    Insect hervivores and pathogens are a major problem in agriculture and therefore, control of these pests and diseases is essential. For this, understanding the plant immune response can be instrumental. The plant hormones salicylic acid (SA) and jasmonic acid (JA) play an essential role in defense

  15. Pachymic acid promotes induction of autophagy related to IGF-1 signaling pathway in WI-38 cells.

    Lee, Su-Gyeong; Kim, Moon-Moo

    2017-12-01

    The insulin-like growth factor 1 (IGF-1) signaling pathway has spotlighted as a mechanism to elucidate aging associated with autophagy in recent years. Therefore, we have tried to screen an effective compound capable of inducing autophagy to delay aging process. The aim of this study is to investigate whether pachymic acid, a main compound in Poria cocos, induces autophagy in the aged cells. The aging of young cells was induced by treatment with IGF-1 at 50 ng/ml three times every two days. The effect of pachymic acid on cell viability was evaluated in human lung fibroblasts, WI-38 cells, using MTT assay. The induction of autophagy was detected using autophagy detection kit. The expression of proteins related to autophagy and IGF-1 signaling pathway was examined by western blot analysis and immunofluorescence assay. In this study, pachymic acid showed cytotoxic effect in a dose dependent manner and remarkably induced autophagy at the same time. Moreover, pachymic acid increased the expression of proteins related to autophagy such as LC3-II and Beclin1 and decreased the levels of mTor phosphorylation and p70S6K in the aged cells. In particular, pachymic acid increased the expression of p-PI3K, p-FoxO and Catalase. In addition, pachymic acid remarkably increased the expression of IGFBP-3. Above results suggest that pachymic acid could induce autophagy related to IGF-1 signaling pathway in the aged cells. Copyright © 2017 Elsevier GmbH. All rights reserved.

  16. The octadecanoid signalling pathway in plants mediates a response to ultraviolet radiation

    Conconi, A.; Smerdon, M.J.; Howe, G.A.; Ryan, C.A.

    1996-01-01

    Many plant genes that respond to environmental and developmental changes are regulated by jasmonic acid, which is derived from linolenic acid via the octadecanoid pathway. Linolenic acid is an important fatty-acid constituent of membranes in most plant species and its intracellular levels increase in response to certain signals. Here we report that irradiation of tomato leaves with ultraviolet light induces the expression of several plant defensive genes that are normally activated through the octadecanoid pathway after wounding. The response to ultraviolet light is blocked by an inhibitor of the octadecanoid pathway and it does not occur in a tomato mutant defective in this pathway. The ultraviolet irradiation maximally induces the defence genes at levels where cyclobutane pyrimidine dimer formation, an indicator of DNA damage, is less than 0.2 dimers per gene. Our evidence indicates that this plant defence response to certain wavelengths of ultraviolet radiation requires the activation of the octadecanoid defence signalling pathway. (author)

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

    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. © 2014 Institute of Botany, Chinese Academy of Sciences.

  18. CKB1 is involved in abscisic acid and gibberellic acid signaling to regulate stress responses in Arabidopsis thaliana.

    Yuan, Congying; Ai, Jianping; Chang, Hongping; Xiao, Wenjun; Liu, Lu; Zhang, Cheng; He, Zhuang; Huang, Ji; Li, Jinyan; Guo, Xinhong

    2017-05-01

    Casein kinase II (CK2), an evolutionarily well-conserved Ser/Thr kinase, plays critical roles in all higher organisms including plants. CKB1 is a regulatory subunit beta of CK2. In this study, homozygous T-DNA mutants (ckb1-1 and ckb1-2) and over-expression plants (35S:CKB1-1, 35S:CKB1-2) of Arabidopsis thaliana were studied to understand the role of CKB1 in abiotic stress and gibberellic acid (GA) signaling. Histochemical staining showed that although CKB1 was expressed in all organs, it had a relatively higher expression in conducting tissues. The ckb1 mutants showed reduced sensitivity to abscisic acid (ABA) during seed germination and seedling growth. The increased stomatal aperture, leaf water loss and proline accumulation were observed in ckb1 mutants. In contrast, the ckb1 mutant had increased sensitivity to polyaluminum chloride during seed germination and hypocotyl elongation. We obtained opposite results in over-expression plants. The expression levels of a number of genes in the ABA and GA regulatory network had changed. This study demonstrates that CKB1 is an ABA signaling-related gene, which subsequently influences GA metabolism, and may play a positive role in ABA signaling.

  19. Insulin signaling regulates fatty acid catabolism at the level of CoA activation.

    Xiaojun Xu

    2012-01-01

    Full Text Available The insulin/IGF signaling pathway is a highly conserved regulator of metabolism in flies and mammals, regulating multiple physiological functions including lipid metabolism. Although insulin signaling is known to regulate the activity of a number of enzymes in metabolic pathways, a comprehensive understanding of how the insulin signaling pathway regulates metabolic pathways is still lacking. Accepted knowledge suggests the key regulated step in triglyceride (TAG catabolism is the release of fatty acids from TAG via the action of lipases. We show here that an additional, important regulated step is the activation of fatty acids for beta-oxidation via Acyl Co-A synthetases (ACS. We identify pudgy as an ACS that is transcriptionally regulated by direct FOXO action in Drosophila. Increasing or reducing pudgy expression in vivo causes a decrease or increase in organismal TAG levels respectively, indicating that pudgy expression levels are important for proper lipid homeostasis. We show that multiple ACSs are also transcriptionally regulated by insulin signaling in mammalian cells. In sum, we identify fatty acid activation onto CoA as an important, regulated step in triglyceride catabolism, and we identify a mechanistic link through which insulin regulates lipid homeostasis.

  20. Branched-chain amino acid supplementation: impact on signaling and relevance to critical illness.

    Mattick, John S A; Kamisoglu, Kubra; Ierapetritou, Marianthi G; Androulakis, Ioannis P; Berthiaume, Francois

    2013-01-01

    The changes that occur in mammalian systems following trauma and sepsis, termed systemic inflammatory response syndrome, elicit major changes in carbohydrate, protein, and energy metabolism. When these events persist for too long they result in a severe depletion of lean body mass, multiple organ dysfunction, and eventually death. Nutritional supplementation has been investigated to offset the severe loss of protein, and recent evidence suggests that diets enriched in branched-chain amino acids (BCAAs) may be especially beneficial. BCAAs are metabolized in two major steps that are differentially expressed in muscle and liver. In muscle, BCAAs are reversibly transaminated to the corresponding α-keto acids. For the complete degradation of BCAAs, the α-keto acids must travel to the liver to undergo oxidation. The liver, in contrast to muscle, does not significantly express the branched-chain aminotransferase. Thus, BCAA degradation is under the joint control of both liver and muscle. Recent evidence suggests that in liver, BCAAs may perform signaling functions, more specifically via activation of mTOR (mammalian target of rapamycin) signaling pathway, influencing a wide variety of metabolic and synthetic functions, including protein translation, insulin signaling, and oxidative stress following severe injury and infection. However, understanding of the system-wide effects of BCAAs that integrate both metabolic and signaling aspects is currently lacking. Further investigation in this respect will help rationalize the design and optimization of nutritional supplements containing BCAAs for critically ill patients. Copyright © 2013 Wiley Periodicals, Inc.

  1. Basic aspects of tumor cell fatty acid-regulated signaling and transcription factors.

    Comba, Andrea; Lin, Yi-Hui; Eynard, Aldo Renato; Valentich, Mirta Ana; Fernandez-Zapico, Martín Ernesto; Pasqualini, Marìa Eugenia

    2011-12-01

    This article reviews the current knowledge and experimental research about the mechanisms by which fatty acids and their derivatives control specific gene expression involved during carcinogenesis. Changes in dietary fatty acids, specifically the polyunsaturated fatty acids of the ω-3 and ω-6 families and some derived eicosanoids from lipoxygenases, cyclooxygenases, and cytochrome P-450, seem to control the activity of transcription factor families involved in cancer cell proliferation or cell death. Their regulation may be carried out either through direct binding to DNA as peroxisome proliferator-activated receptors or via modulation in an indirect manner of signaling pathway molecules (e.g., protein kinase C) and other transcription factors (nuclear factor kappa B and sterol regulatory element binding protein). Knowledge of the mechanisms by which fatty acids control specific gene expression may identify important risk factors for cancer and provide insight into the development of new therapeutic strategies for a better management of whole body lipid metabolism.

  2. Extensive mass spectrometry proteomics data of Persicaria minor herb upon methyl jasmonate treatment

    Wan Mohd Aizat

    2018-02-01

    Full Text Available Proteomics is often hindered by the lack of protein sequence database particularly for non-model species such as Persicaria minor herbs. An integrative approach called proteomics informed by transcriptomics is possible [1], in which translated transcriptome sequence database is used as the protein sequence database. In this current study, the proteome profile were profiled using SWATH-MS technology complemented with documented transcriptome profiling [2], the first such report in this tropical herb. The plant was also elicited using a phytohormone, methyl jasmonate (MeJA and protein changes were elucidated using label-free quantification of SWATH-MS to understand the role of such signal molecule in this herbal species. The mass spectrometry proteomics data was deposited to the ProteomeXchange Consortium via the PRIDE partner repository with the dataset identifier PXD005749. This data article refers to the article entitled “Proteomics (SWATH-MS-informed by transcriptomics approach of Persicaria minor leaves upon methyl jasmonate elicitation” [3].

  3. Methyl Jasmonate: An Alternative for Improving the Quality and Health Properties of Fresh Fruits

    Marjorie Reyes-Díaz

    2016-05-01

    Full Text Available Methyl jasmonate (MeJA is a plant growth regulator belonging to the jasmonate family. It plays an important role as a possible airborne signaling molecule mediating intra- and inter-plant communications and modulating plant defense responses, including antioxidant systems. Most assessments of this compound have dealt with post-harvest fruit applications, demonstrating induced plant resistance against the detrimental impacts of storage (chilling injuries and pathogen attacks, enhancing secondary metabolites and antioxidant activity. On the other hand, the interactions between MeJA and other compounds or technological tools for enhancing antioxidant capacity and quality of fruits were also reviewed. The pleiotropic effects of MeJA have raisen numerous as-yet unanswered questions about its mode of action. The aim of this review was endeavored to clarify the role of MeJA on improving pre- and post-harvest fresh fruit quality and health properties. Interestingly, the influence of MeJA on human health will be also discussed.

  4. Effect of methyl jasmonate and silver nanoparticles on production of ...

    Conclusion: Treatment of C. officinalis L. with SNPs and MeJA seems to be a simple and cost-effective method of improving the medicinal properties of this plant. Keywords: Calendula officinalis, Silver nanoparticles, Methyl jasmonate, Secondary metabolites, HeLa cells, Membrane lipid peroxidation, Radical scavenging ...

  5. The necrotic signal induced by mycophenolic acid overcomes apoptosis-resistance in tumor cells.

    Gwendaline Guidicelli

    Full Text Available BACKGROUND: The amount of inosine monophosphate dehydrogenase (IMPDH, a pivotal enzyme for the biosynthesis of the guanosine tri-phosphate (GTP, is frequently increased in tumor cells. The anti-viral agent ribavirin and the immunosuppressant mycophenolic acid (MPA are potent inhibitors of IMPDH. We recently showed that IMPDH inhibition led to a necrotic signal requiring the activation of Cdc42. METHODOLOGY/PRINCIPAL FINDINGS: Herein, we strengthened the essential role played by this small GTPase in the necrotic signal by silencing Cdc42 and by the ectopic expression of a constitutive active mutant of Cdc42. Since resistance to apoptosis is an essential step for the tumorigenesis process, we next examined the effect of the MPA-mediated necrotic signal on different tumor cells demonstrating various mechanisms of resistance to apoptosis (Bcl2-, HSP70-, Lyn-, BCR-ABL-overexpressing cells. All tested cells remained sensitive to MPA-mediated necrotic signal. Furthermore, inhibition of IMPDH activity in Chronic Lymphocytic Leukemia cells was significantly more efficient at eliminating malignant cells than apoptotic inducers. CONCLUSIONS/SIGNIFICANCE: These findings indicate that necrosis and apoptosis are split signals that share few if any common hub of signaling. In addition, the necrotic signaling pathway induced by depletion of the cellular amount of GTP/GDP would be of great interest to eliminate apoptotic-resistant tumor cells.

  6. Regulatory cross-talks and cascades in rice hormone biosynthesis pathways contribute to stress signaling

    Arindam Deb

    2016-08-01

    Full Text Available Crosstalk among different hormone signaling pathways play an important role in modulating plant response to both biotic and abiotic stress. Hormone activity is controlled by its bio-availability, which is again influenced by its biosynthesis. Thus independent hormone biosynthesis pathways must be regulated and co-ordinated to mount an integrated response. One of the possibilities is to use cis-regulatory elements to orchestrate expression of hormone biosynthesis genes. Analysis of CREs, associated with differentially expressed hormone biosynthesis related genes in rice leaf under Magnaporthe oryzae attack and drought stress enabled us to obtain insights about cross-talk among hormone biosynthesis pathways at the transcriptional level. We identified some master transcription regulators that co-ordinate different hormone biosynthesis pathways under stress. We found that Abscisic acid and Brassinosteroid regulate Cytokinin conjugation; conversely Brassinosteroid biosynthesis is affected by both Abscisic acid and Cytokinin. Jasmonic acid and Ethylene biosynthesis may be modulated by Abscisic acid through DREB transcription factors. Jasmonic acid or Salicylic acid biosynthesis pathways are co-regulated but they are unlikely to influence each other’s production directly. Thus multiple hormones may modulate hormone biosynthesis pathways through a complex regulatory network, where biosynthesis of one hormone is affected by several other contributing hormones.

  7. Does methyl jasmonate modify the oxidative stress response in Phaseolus coccineus treated with Cu?

    Hanaka, Agnieszka; Wójcik, Małgorzata; Dresler, Sławomir; Mroczek-Zdyrska, Magdalena; Maksymiec, Waldemar

    2016-02-01

    The contribution of methyl jasmonate (MJ) as a signal molecule able to take part in the defense mechanism against copper (Cu)-imposed oxidative stress was studied in the leaves and roots of runner bean (Phaseolus coccineus) plants. Roots of plants cultivated hydroponically were preincubated in MJ (10µM) for 1h or 24h and subsequently exposed to Cu (50µM) for 5h (short-term experiment) or 5 days (long-term experiment). Enzymatic (activity of superoxide dismutase, SOD; catalase, CAT; ascorbate peroxidase, APX; guaiacol peroxidase, POX) and non-enzymatic (accumulation of malondialdehyde, MDA; homoglutathione, hGSH; proline; anthocyanins; low molecular weight organic acids, LMWOAs) responses were determined in the leaves and roots. The antioxidative defense mechanism was significantly activated after Cu supplementation. In most cases, activities of ROS (reactive oxygen species) scavenging enzymes like SOD, CAT, APX, POX, as well as MDA, hGSH and proline concentrations increased following Cu exposure. MJ showed a time-dependent effect on antioxidative enzymes activity. In the short-term experiment, MJ elevated CAT, APX and POX activities in the roots, and POX activity in the leaves of non-Cu-treated plants. In the long-term experiment, MJ not only decreased POX and partially CAT activity in the roots, but also increased the MDA level and partially CAT activity in the leaves of the control plants. In Cu-treated plants, MJ reduced APX, but elevated POX activity in the leaves after 5-h exposure. After 5-day-Cu treatment, MJ inhibited POX activity in the leaves and mainly reduced SOD and CAT activities in the roots. Moreover, in the long-term experiment, MJ reduced tartrate and pyruvate in the leaves of Cu-stressed plants, but mostly elevated tartrate and malate in the roots comparing with Cu alone treatment. MJ alone and under Cu excess did not alter accumulation of MDA, hGSH and proline comparing with Cu alone, but partially elevated anthocyanin concentration. The

  8. An iron 13S-lipoxygenase with an α-linolenic acid specific hydroperoxidase activity from Fusarium oxysporum.

    Florian Brodhun

    Full Text Available Jasmonates constitute a family of lipid-derived signaling molecules that are abundant in higher plants. The biosynthetic pathway leading to plant jasmonates is initiated by 13-lipoxygenase-catalyzed oxygenation of α-linolenic acid into its 13-hydroperoxide derivative. A number of plant pathogenic fungi (e.g. Fusarium oxysporum are also capable of producing jasmonates, however, by a yet unknown biosynthetic pathway. In a search for lipoxygenase in F. oxysporum, a reverse genetic approach was used and one of two from the genome predicted lipoxygenases (FoxLOX was cloned. The enzyme was heterologously expressed in E. coli, purified via affinity chromatography, and its reaction mechanism characterized. FoxLOX was found to be a non-heme iron lipoxygenase, which oxidizes C18-polyunsaturated fatty acids to 13S-hydroperoxy derivatives by an antarafacial reaction mechanism where the bis-allylic hydrogen abstraction is the rate-limiting step. With α-linolenic acid as substrate FoxLOX was found to exhibit a multifunctional activity, because the hydroperoxy derivatives formed are further converted to dihydroxy-, keto-, and epoxy alcohol derivatives.

  9. Abscisic Acid as a Dominant Signal in Tomato During Salt Stress Predisposition to Phytophthora Root and Crown Rot

    Matthew F. Pye

    2018-04-01

    Full Text Available Salt stress predisposes plants to Phytophthora root and crown rot in an abscisic acid (ABA-dependent manner. We used the tomato–Phytophthora capsici interaction to examine zoospore chemoattraction and assessed expression of pathogenesis-related (PR genes regulated by salicylic acid (SA and jasmonic acid (JA following a salt-stress episode. Although salt treatment enhances chemoattraction of tomato roots to zoospores, exudates from salt-stressed roots of ABA-deficient mutants, which do not display the predisposition phenotype, have a similar chemoattraction as exudates from salt-stressed, wild-type roots. This suggests that ABA action during predisposing stress enhances disease through effects on plant responses occurring after initial contact and during ingress by the pathogen. The expression of NCED1 (ABA synthesis and TAS14 (ABA response in roots generally corresponded to previously reported changes in root ABA levels during salt stress onset and recovery in a pattern that was not altered by infection by P. capsici. The PR genes, P4 and PI-2, hallmarks in tomato for SA and JA action, respectively, were induced in non-stressed roots during infection and strongly suppressed in infected roots exposed to salt-stress prior to inoculation. However, there was a similar proportional increase in pathogen colonization observed in salt-stressed plants relative to non-stressed plants in both wild-type and a SA-deficient nahG line. Unlike the other tomato cultivars used in this study that showed a strong predisposition phenotype, the processing tomato cv. ‘Castlemart’ and its JA mutants were not predisposed by salt. Salt stress predisposition to crown and root rot caused by P. capsici appears to be strongly conditioned by ABA-driven mechanisms in tomato, with the stress compromising SA-and JA-mediated defense-related gene expression during P. capsici infection.

  10. Influence of jasmonic acid as potential activator of induced ...

    MADU

    seed vigor and reduction in market acceptability of the produce. ... effect prior to the challenge of infection and induces defense against KB probably by maintaining a critical balance ..... could be a strategy to combat KB infection through.

  11. GLABROUS INFLORESCENCE STEMS (GIS) is required for trichome branching through gibberellic acid signaling in Arabidopsis.

    An, Lijun; Zhou, Zhongjing; Su, Sha; Yan, An; Gan, Yinbo

    2012-02-01

    Cell differentiation generally corresponds to the cell cycle, typically forming a non-dividing cell with a unique differentiated morphology, and Arabidopsis trichome is an excellent model system to study all aspects of cell differentiation. Although gibberellic acid is reported to be involved in trichome branching in Arabidopsis, the mechanism for such signaling is unclear. Here, we demonstrated that GLABROUS INFLORESCENCE STEMS (GIS) is required for the control of trichome branching through gibberellic acid signaling. The phenotypes of a loss-of-function gis mutant and an overexpressor showed that GIS acted as a repressor to control trichome branching. Our results also show that GIS is not required for cell endoreduplication, and our molecular and genetic study results have shown that GIS functions downstream of the key regulator of trichome branching, STICHEL (STI), to control trichome branching through the endoreduplication-independent pathway. Furthermore, our results also suggest that GIS controls trichome branching in Arabidopsis through two different pathways and acts either upstream or downstream of the negative regulator of gibbellic acid signaling SPINDLY (SPY).

  12. Monoglyceride lipase as a drug target: At the crossroads of arachidonic acid metabolism and endocannabinoid signaling.

    Grabner, Gernot F; Zimmermann, Robert; Schicho, Rudolf; Taschler, Ulrike

    2017-07-01

    Monoglyerides (MGs) are short-lived, intermediary lipids deriving from the degradation of phospho- and neutral lipids, and monoglyceride lipase (MGL), also designated as monoacylglycerol lipase (MAGL), is the major enzyme catalyzing the hydrolysis of MGs into glycerol and fatty acids. This distinct function enables MGL to regulate a number of physiological and pathophysiological processes since both MGs and fatty acids can act as signaling lipids or precursors thereof. The most prominent MG species acting as signaling lipid is 2-arachidonoyl glycerol (2-AG) which is the most abundant endogenous agonist of cannabinoid receptors in the body. Importantly, recent observations demonstrate that 2-AG represents a quantitatively important source for arachidonic acid, the precursor of prostaglandins and other inflammatory mediators. Accordingly, MGL-mediated 2-AG degradation affects lipid signaling by cannabinoid receptor-dependent and independent mechanisms. Recent genetic and pharmacological studies gave important insights into MGL's role in (patho-)physiological processes, and the enzyme is now considered as a promising drug target for a number of disorders including cancer, neurodegenerative and inflammatory diseases. This review summarizes the basics of MG (2-AG) metabolism and provides an overview on the therapeutic potential of MGL. Copyright © 2017 Elsevier Inc. All rights reserved.

  13. Does perinatal omega-3 polyunsaturated fatty acid deficiency increase appetite signaling?

    Mathai, Michael L; Soueid, Mona; Chen, Nora; Jayasooriya, Anura P; Sinclair, Andrew J; Wlodek, Mary E; Weisinger, Harrison S; Weisinger, Richard S

    2004-11-01

    To investigate the effect of maternal dietary omega-3 polyunsaturated fatty acid (PUFA) deficiency and repletion on food appetite signaling. Sprague-Dawley rat dams were maintained on diets either supplemented with (CON) or deficient in (DEF) omega-3 PUFA. All offspring were raised on the maternal diet until weaning. After weaning, two groups remained on the respective maternal diet (CON and DEF groups), whereas a third group, born of dams fed the DEF diet, were switched to the CON diet (REC). Experiments on food intake began when the male rats reached 16 weeks of age. Food intake was stimulated either by a period of food restriction, by blocking glucose utilization (by 2-deoxyglucose injection), or by blocking beta-oxidation of fatty acids (by beta-mercaptoacetate injection). DEF animals consumed more than CON animals in response to all stimuli, with the greatest difference (1.9-fold) demonstrated following administration of 2-deoxyglucose. REC animals also consumed more than CON animals in response to food restriction and 2-deoxyglucose but not to beta-mercaptoacetate. These findings indicate that supply of omega-3 PUFA, particularly during the perinatal period, plays a role in the normal development of mechanisms controlling food intake, especially glucoprivic (i.e. reduced glucose availability) appetite signaling. Dietary repletion of omega-3 PUFA from 3 weeks of age restored intake responses to fatty acid metabolite signaling but did not reverse those in response to food restriction or glucoprivic stimuli.

  14. Transcriptome analysis of an mvp mutant reveals important changes in global gene expression and a role for methyl jasmonate in vernalization and flowering in wheat.

    Diallo, Amadou Oury; Agharbaoui, Zahra; Badawi, Mohamed A; Ali-Benali, Mohamed Ali; Moheb, Amira; Houde, Mario; Sarhan, Fathey

    2014-06-01

    The einkorn wheat mutant mvp-1 (maintained vegetative phase 1) has a non-flowering phenotype caused by deletions including, but not limited to, the genes CYS, PHYC, and VRN1. However, the impact of these deletions on global gene expression is still unknown. Transcriptome analysis showed that these deletions caused the upregulation of several pathogenesis-related (PR) and jasmonate-responsive genes. These results suggest that jasmonates may be involved in flowering and vernalization in wheat. To test this hypothesis, jasmonic acid (JA) and methyl jasmonate (MeJA) content in mvp and wild-type plants was measured. The content of JA was comparable in all plants, whereas the content of MeJA was higher by more than 6-fold in mvp plants. The accumulation of MeJA was also observed in vernalization-sensitive hexaploid winter wheat during cold exposure. This accumulation declined rapidly once plants were deacclimated under floral-inductive growth conditions. This suggests that MeJA may have a role in floral transition. To confirm this result, we treated vernalization-insensitive spring wheat with MeJA. The treatment delayed flowering with significant downregulation of both TaVRN1 and TaFT1 genes. These data suggest a role for MeJA in modulating vernalization and flowering time in wheat. © The Author 2014. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  15. ISOLATION AND CHARACTERIZATION OF AXOLOTL NPDC-1 AND ITS EFFECTS ON RETINOIC ACID RECEPTOR SIGNALING

    Theodosiou, Maria; Monaghan, James R; Spencer, Michael L; Voss, S Randal; Noonan, Daniel J

    2009-01-01

    Retinoic acid, a key morphogen in early vertebrate development and tissue regeneration, mediates its effects through the binding of receptors that act as ligand-induced transcription factors. These binding events function to recruit an array of transcription co-regulatory proteins to specific gene promoters. One such co-regulatory protein, neuronal proliferation and differentiation control-1 (NPDC-1), is broadly expressed during mammalian development and functions as an in vitro repressor of retinoic acid receptor (RAR)-mediated transcription. To obtain comparative and developmental insights about NPDC-1 function, we cloned the axolotl (Ambystoma mexicanum) orthologue and measured transcript abundances among tissues sampled during the embryonic and juvenile phases of development, and also during spinal cord regeneration. Structurally, the axolotl orthologue of NPDC-1 retained sequence identity to mammalian sequences in all functional domains. Functionally, we observed that axolotl NPDC-1 mRNA expression peaked late in embryogenesis, with highest levels of expression occurring during the time of limb development, a process regulated by retinoic acid signaling. Also similar to what has been observed in mammals, axolotl NPDC-1 directly interacts with axolotl RAR, modulates axolotl RAR DNA binding, and represses cell proliferation and axolotl RAR-mediated gene transcription. These data justify axolotl as a model to further investigate NPDC-1 and its role in regulating retinoic acid signaling. PMID:17331771

  16. A traffic signal for heterodimeric amino acid transporters to transfer from the ER to the Golgi.

    Ganapathy, Vadivel

    2009-01-15

    Heterodimeric amino acid transporters represent a unique class of transport systems that consist of a light chain that serves as the 'transporter proper' and a heavy chain that is necessary for targeting the complex to the plasma membrane. The currently prevailing paradigm assigns no role for the light chains in the cellular processing of these transporters. In this issue of the Biochemical Journal, Sakamoto et al. provide evidence contrary to this paradigm. Their studies with the rBAT -b(0,+)AT (related to b(0,+) amino acid transporter-b(0,+)-type amino acid transporter) heterodimeric amino acid transporter show that the C-terminus of the light chain b(0,+)AT contains a sequence motif that serves as the traffic signal for the transfer of the heterodimeric complex from the endoplasmic reticulum to the Golgi. This is a novel function for the light chain in addition to its already established role as the subunit responsible for the transport activity. These new findings also seem to be applicable to other heterodimeric amino acid transporters as well.

  17. Nitro-fatty acids in plant signaling: New key mediators of nitric oxide metabolism

    Capilla Mata-Pérez

    2017-04-01

    Full Text Available Recent studies in animal systems have shown that NO can interact with fatty acids to generate nitro-fatty acids (NO2-FAs. They are the product of the reaction between reactive nitrogen species and unsaturated fatty acids, and are considered novel mediators of cell signaling based mainly on a proven anti-inflammatory response. Although these signaling mediators have been described widely in animal systems, NO2-FAs have scarcely been studied in plants. Preliminary data have revealed the endogenous presence of free and protein-adducted NO2-FAs in extra-virgin olive oil (EVOO, which appear to be contributing to the cardiovascular benefits associated with the Mediterranean diet. Importantly, new findings have displayed the endogenous occurrence of nitro-linolenic acid (NO2-Ln in the model plant Arabidopsis thaliana and the modulation of NO2-Ln levels throughout this plant's development. Furthermore, a transcriptomic analysis by RNA-seq technology established a clear signaling role for this molecule, demonstrating that NO2-Ln was involved in plant-defense response against different abiotic-stress conditions, mainly by inducing the chaperone network and supporting a conserved mechanism of action in both animal and plant defense processes. Thus, NO2-Ln levels significantly rose under several abiotic-stress conditions, highlighting the strong signaling role of these molecules in the plant-protection mechanism. Finally, the potential of NO2-Ln as a NO donor has recently been described both in vitro and in vivo. Jointly, this ability gives NO2-Ln the potential to act as a signaling molecule by the direct release of NO, due to its capacity to induce different changes mediated by NO or NO-related molecules such as nitration and S-nitrosylation, or by the electrophilic capacity of these molecules through a nitroalkylation mechanism. Here, we describe the current state of the art regarding the advances performed in the field of NO2-FAs in plants and their

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

    Chen, Hao; Xiong, Liming

    2011-01-01

    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

  19. AI-2 signalling is induced by acidic shock in probiotic strains of Lactobacillus spp.

    Moslehi-Jenabian, Saloomeh; Gori, Klaus; Jespersen, Lene

    2009-11-15

    Survival and ability to respond to various environmental stresses such as low pH are important factors for lactobacilli for their function as probiotics. LuxS-mediated quorum sensing mechanism, which is based on the production of universal signal molecule called autoinducer-2 (AI-2), regulates important physiological traits and a variety of adaptive processes in different bacteria. The aim of this study was to investigate the effect of acidic stress on LuxS-mediated quorum sensing (AI-2 signalling) in four probiotic strains of different Lactobacillus species. Initially, the production of AI-2-like molecule was investigated in four strains of Lactobacillus spp. at standard growth conditions using Vibrio harveyi bioluminescence assay. Species variation in AI-2 activity was observed. AI-2 activity started at early-exponential growth phase and increased during the mid-exponential phase concomitant with the reduction of pH, reaching maximum at late exponential phase (L. rhamnosus GG) or at stationary phase (L. salivarius UCC118, L. acidophilus NCFM and L. johnsonii NCC533). Acidic shock experiments were conducted on L. rhamnosus GG and L. acidophilus NCFM after exposure to different acidic shocks (pH 5.0, 4.0 and 3.0) and to pH 6.5 as control, measuring AI-2 activity and transcription of the luxS gene. AI-2 activity increased by lowering the pH in a dose dependent manner and was negatively influenced by acid adaptation. In both species, the luxS gene was repressed after exposure to pH 6.5 as control. However, after acidic shock (pH 4.0) a transient response of luxS gene was observed and the transcription augmented over time, reaching a maximum level and decreased subsequently. Acid adaptation of cells attenuated the transcription of this gene. Based on the observations done in the present study, the luxS gene appears to have a clear role in acidic stress response in probiotic lactobacilli. This might be important in the survival of these bacteria during the passage

  20. A single amino acid residue controls Ca2+ signaling by an octopamine receptor from Drosophila melanogaster.

    Hoff, Max; Balfanz, Sabine; Ehling, Petra; Gensch, Thomas; Baumann, Arnd

    2011-07-01

    Rhythmic activity of cells and cellular networks plays an important role in physiology. In the nervous system oscillations of electrical activity and/or second messenger concentrations are important to synchronize neuronal activity. At the molecular level, rhythmic activity can be initiated by different routes. We have recently shown that an octopamine-activated G-protein-coupled receptor (GPCR; DmOctα1Rb, CG3856) from Drosophila initiates Ca(2+) oscillations. Here, we have unraveled the molecular basis of cellular Ca(2+) signaling controlled by the DmOctα1Rb receptor using a combination of pharmacological intervention, site-directed mutagenesis, and functional cellular Ca(2+) imaging on heterologously expressed receptors. Phosphorylation of a single amino acid residue in the third intracellular loop of the GPCR by PKC is necessary and sufficient to desensitize the receptor. From its desensitized state, DmOctα1Rb is resensitized by dephosphorylation, and a new Ca(2+) signal occurs on octopamine stimulation. Our findings show that transient changes of the receptor's surface profile have a strong effect on its physiological signaling properties. We expect that the detailed knowledge of DmOctα1Rb-dependent signal transduction fosters the identification of specific drugs that can be used for GPCR-mediated pest control, since octopamine serves important physiological and behavioral functions in arthropods.

  1. Sugar signaling regulation by Arabidopsis SIZ1-driven sumoylation is independent of salicylic acid

    Castro, Pedro Humberto Araújo R F; Verde, Nuno; Tavares, Rui Manuel

    2018-01-01

    inefficient responses to nutrient imbalance in phosphate, nitrate and copper. Recently, we reported that siz1 also displays altered responses to exogenous sugar supplementation. The siz1 mutant is a salicylic acid (SA) accumulator, and SA may interfere with sugar-dependent responses and signaling events. Here......, we extended our previous studies to determine the importance of SA in the SIZ1 response to sugars, by introducing the bacterial salicylate hydroxylase NahG into the siz1 background. Results demonstrate that siz1 phenotypes involving delayed germination are partially dependent of SA levels, whereas...

  2. IMAGING BRAIN SIGNAL TRANSDUCTION AND METABOLISM VIA ARACHIDONIC AND DOCOSAHEXAENOIC ACID IN ANIMALS AND HUMANS

    Basselin, Mireille; Ramadan, Epolia; Rapoport, Stanley I.

    2012-01-01

    The polyunsaturated fatty acids (PUFAs), arachidonic acid (AA, 20:4n-6) and docosahexaenoic acid (DHA, 22:6n-3), important second messengers in brain, are released from membrane phospholipid following receptor-mediated activation of specific phospholipase A2 (PLA2) enzymes. We developed an in vivo method in rodents using quantitative autoradiography to image PUFA incorporation into brain from plasma, and showed that their incorporation rates equal their rates of metabolic consumption by brain. Thus, quantitative imaging of unesterified plasma AA or DHA incorporation into brain can be used as a biomarker of brain PUFA metabolism and neurotransmission. We have employed our method to image and quantify effects of mood stabilizers on brain AA/DHA incorporation during neurotransmission by muscarinic M1,3,5, serotonergic 5-HT2A/2C, dopaminergic D2-like (D2, D3, D4) or glutamatergic N-methyl-D-aspartic acid (NMDA) receptors, and effects of inhibition of acetylcholinesterase, of selective serotonin and dopamine reuptake transporter inhibitors, of neuroinflammation (HIV-1 and lipopolysaccharide) and excitotoxicity, and in genetically modified rodents. The method has been extended for the use with positron emission tomography (PET), and can be employed to determine how human brain AA/DHA signaling and consumption are influenced by diet, aging, disease and genetics. PMID:22178644

  3. Androgen receptor and nutrient signaling pathways coordinate the demand for increased amino acid transport during prostate cancer progression

    Wang, Qian; Bailey, Charles G; Ng, Cynthia

    2011-01-01

    was sufficient to decrease cell growth and mTORC1 signaling in prostate cancer cells. These cells maintained levels of amino acid influx through androgen receptor-mediated regulation of LAT3 expression and ATF4 regulation of LAT1 expression after amino acid deprivation. These responses remained intact in primary......L-Type amino acid transporters such as LAT1 and LAT3 mediate the uptake of essential amino acids. Here, we report that prostate cancer cells coordinate the expression of LAT1 and LAT3 to maintain sufficient levels of leucine needed for mTORC1 signaling and cell growth. Inhibiting LAT function...... prostate cancer, as indicated by high levels of LAT3 in primary disease, and by increased levels of LAT1 after hormone ablation and in metastatic lesions. Taken together, our results show how prostate cancer cells respond to demands for increased essential amino acids by coordinately activating amino acid...

  4. Nicotinic Acid Increases Adiponectin Secretion from Differentiated Bovine Preadipocytes through G-Protein Coupled Receptor Signaling

    Christina Kopp

    2014-11-01

    Full Text Available The transition period in dairy cows (3 weeks prepartum until 3 weeks postpartum is associated with substantial mobilization of energy stores, which is often associated with metabolic diseases. Nicotinic acid (NA is an antilipolytic and lipid-lowering compound used to treat dyslipidaemia in humans, and it also reduces non-esterified fatty acids in cattle. In mice the G-protein coupled receptor 109A (GPR109A ligand NA positively affects the secretion of adiponectin, an important modulator of glucose and fat metabolism. In cattle, the corresponding data linking NA to adiponectin are missing. Our objective was to examine the effects of NA on adiponectin and AMPK protein abundance and the expression of mRNAs of related genes such as chemerin, an adipokine that enhances adiponectin secretion in vitro. Differentiated bovine adipocytes were incubated with pertussis toxin (PTX to verify the involvement of GPR signaling, and treated with 10 or 15 µM NA for 12 or 24 h. NA increased adiponectin concentrations (p ≤ 0.001 and the mRNA abundances of GPR109A (p ≤ 0.05 and chemerin (p ≤ 0.01. Pre-incubation with PTX reduced the adiponectin response to NA (p ≤ 0.001. The NA-stimulated secretion of adiponectin and the mRNA expression of chemerin in the bovine adipocytes were suggestive of GPR signaling-dependent improved insulin sensitivity and/or adipocyte metabolism in dairy cows.

  5. Kaempferol Isolated from Nelumbo nucifera Inhibits Lipid Accumulation and Increases Fatty Acid Oxidation Signaling in Adipocytes.

    Lee, Bonggi; Kwon, Misung; Choi, Jae Sue; Jeong, Hyoung Oh; Chung, Hae Young; Kim, Hyeung-Rak

    2015-12-01

    Stamens of Nelumbo nucifera Gaertn have been used as a Chinese medicine due to its antioxidant, hypoglycemic, and antiatherogenic activity. However, the effects of kaempferol, a main component of N. nucifera, on obesity are not fully understood. We examined the effect of kaempferol on adipogenesis and fatty acid oxidation signaling pathways in 3T3-L1 adipocytes. Kaempferol reduced cytoplasmic triglyceride (TG) accumulation in dose and time-dependent manners during adipocyte differentiation. Accumulation of TG was rapidly reversed by retrieving kaempferol treatment. Kaempferol broadly decreased mRNA or protein levels of adipogenic transcription factors and their target genes related to lipid accumulation. Kaempferol also suppressed glucose uptake and glucose transporter GLUT4 mRNA expression in adipocytes. Furthermore, protein docking simulation suggests that Kaempferol can directly bind to and activate peroxisome proliferator-activated receptor (PPAR)-α by forming hydrophobic interactions with VAL324, THR279, and LEU321 residues of PPARα. The binding affinity was higher than a well-known PPARα agonist fenofibrate. Consistently, mRNA expression levels of PPARα target genes were increased. Our study indicates while kaempferol inhibits lipogenic transcription factors and lipid accumulation, it may bind to PPARα and stimulate fatty acid oxidation signaling in adipocytes.

  6. Elevated carbon dioxide increases salicylic acid in Glycine max.

    Casteel, Clare L; Segal, Lauren M; Niziolek, Olivia K; Berenbaum, May R; DeLucia, Evan H

    2012-12-01

    Concentrations of carbon dioxide (CO(2)) are increasing in the atmosphere, affecting soybean (Glycine max L.) phytohormone signaling and herbivore resistance. Whether the impact of elevated CO(2) on phytohormones and induced defenses is a generalized response within this species is an open question. We examined jasmonic acid (JA) and salicylic acid (SA) under ambient and elevated CO(2) concentrations with and without Japanese beetle (Popillia japonica Newman) damage and artificial damage across six soybean cultivars (HS93-4118, Pana, IA 3010, Loda, LN97-15076, and Dwight). Elevated CO(2) reduced constitutive levels of JA and related transcripts in some but not all soybean cultivars. In contrast to the variation in JA, constitutive levels of salicylic were increased universally among soybean cultivars grown under elevated CO(2). Variation in hormonal signaling may underpin observed variation in the response of insect herbivores and pathogens to plants grown under elevated CO(2).

  7. Postnatal Ablation of Synaptic Retinoic Acid Signaling Impairs Cortical Information Processing and Sensory Discrimination in Mice.

    Park, Esther; Tjia, Michelle; Zuo, Yi; Chen, Lu

    2018-06-06

    Retinoic acid (RA) and its receptors (RARs) are well established essential transcriptional regulators during embryonic development. Recent findings in cultured neurons identified an independent and critical post-transcriptional role of RA and RARα in the homeostatic regulation of excitatory and inhibitory synaptic transmission in mature neurons. However, the functional relevance of synaptic RA signaling in vivo has not been established. Here, using somatosensory cortex as a model system and the RARα conditional knock-out mouse as a tool, we applied multiple genetic manipulations to delete RARα postnatally in specific populations of cortical neurons, and asked whether synaptic RA signaling observed in cultured neurons is involved in cortical information processing in vivo Indeed, conditional ablation of RARα in mice via a CaMKIIα-Cre or a layer 5-Cre driver line or via somatosensory cortex-specific viral expression of Cre-recombinase impaired whisker-dependent texture discrimination, suggesting a critical requirement of RARα expression in L5 pyramidal neurons of somatosensory cortex for normal tactile sensory processing. Transcranial two-photon imaging revealed a significant increase in dendritic spine elimination on apical dendrites of somatosensory cortical layer 5 pyramidal neurons in these mice. Interestingly, the enhancement of spine elimination is whisker experience-dependent as whisker trimming rescued the spine elimination phenotype. Additionally, experiencing an enriched environment improved texture discrimination in RARα-deficient mice and reduced excessive spine pruning. Thus, RA signaling is essential for normal experience-dependent cortical circuit remodeling and sensory processing. SIGNIFICANCE STATEMENT The importance of synaptic RA signaling has been demonstrated in in vitro studies. However, whether RA signaling mediated by RARα contributes to neural circuit functions in vivo remains largely unknown. In this study, using a RARα conditional

  8. Proliferation of mouse endometrial stromal cells in culture is highly sensitive to lysophosphatidic acid signaling

    Aikawa, Shizu; Kano, Kuniyuki; Inoue, Asuka; Aoki, Junken

    2017-01-01

    Endometrial stromal cells (ESCs) proliferate rapidly both in vivo and in vitro. Here we show that proliferation of ESCs in vitro is strongly dependent on lysophosphatidic acid (LPA) signaling. LPA is produced by autotaxin (ATX) and induces various kinds of cellular processes including migration, proliferation and inhibition of cell death possibly through six G protein-coupled receptors (LPA 1-6 ). We found that ESCs proliferated rapidly in vitro in an autocrine manner and that the proliferation was prominently suppressed by either an ATX inhibitor (ONO-8430506) or an LPA 1/3 antagonist (Ki16425). Among the cells lines tested, mouse ESCs were the most sensitive to these inhibitors. Proliferation of ESCs isolated from either LPA 1 - or LPA 3 -deficient mice was comparable to proliferation of ESCs isolated from control mice. An LPA receptor antagonist (AM095), which was revealed to be a dual LPA 1 /LPA 3 antagonist, also suppressed the proliferation of ESCs. The present results show that LPA signaling has a critical role in the proliferation of ESCs, and that this role is possibly mediated redundantly by LPA 1 and LPA 3 . - Highlights: • Uterine endometrial stromal cells (ESCs) proliferate rapidly both in vivo and in vitro. • ESCs proliferated in vitro in an autocrine fashion. • Proliferation of mouse ESCs was prominently suppressed by inhibitors of lysophosphatidic acid (LPA) signaling. • LPA receptors, LPA 1 and LPA 3 , had redundant role in supporting the proliferation of ESCs.

  9. Retinoic acid receptor signalling directly regulates osteoblast and adipocyte differentiation from mesenchymal progenitor cells

    Green, A.C. [St Vincent' s Institute, Fitzroy, Victoria 3065 (Australia); Department of Medicine at St. Vincent' s Hospital, The University of Melbourne, Victoria 3065 (Australia); Kocovski, P.; Jovic, T.; Walia, M.K. [St Vincent' s Institute, Fitzroy, Victoria 3065 (Australia); Chandraratna, R.A.S. [IO Therapeutics, Inc., Santa Ana, CA 92705 (United States); Martin, T.J.; Baker, E.K. [St Vincent' s Institute, Fitzroy, Victoria 3065 (Australia); Department of Medicine at St. Vincent' s Hospital, The University of Melbourne, Victoria 3065 (Australia); Purton, L.E., E-mail: lpurton@svi.edu.au [St Vincent' s Institute, Fitzroy, Victoria 3065 (Australia); Department of Medicine at St. Vincent' s Hospital, The University of Melbourne, Victoria 3065 (Australia)

    2017-01-01

    Low and high serum retinol levels are associated with increased fracture risk and poor bone health. We recently showed retinoic acid receptors (RARs) are negative regulators of osteoclastogenesis. Here we show RARs are also negative regulators of osteoblast and adipocyte differentiation. The pan-RAR agonist, all-trans retinoic acid (ATRA), directly inhibited differentiation and mineralisation of early osteoprogenitors and impaired the differentiation of more mature osteoblast populations. In contrast, the pan-RAR antagonist, IRX4310, accelerated differentiation of early osteoprogenitors. These effects predominantly occurred via RARγ and were further enhanced by an RARα agonist or antagonist, respectively. RAR agonists similarly impaired adipogenesis in osteogenic cultures. RAR agonist treatment resulted in significant upregulation of the Wnt antagonist, Sfrp4. This accompanied reduced nuclear and cytosolic β-catenin protein and reduced expression of the Wnt target gene Axin2, suggesting impaired Wnt/β-catenin signalling. To determine the effect of RAR inhibition in post-natal mice, IRX4310 was administered to male mice for 10 days and bones were assessed by µCT. No change to trabecular bone volume was observed, however, radial bone growth was impaired. These studies show RARs directly influence osteoblast and adipocyte formation from mesenchymal cells, and inhibition of RAR signalling in vivo impairs radial bone growth in post-natal mice. - Graphical abstract: Schematic shows RAR ligand regulation of osteoblast differentiation in vitro. RARγ antagonists±RARα antagonists promote osteoblast differentiation. RARγ and RARα agonists alone or in combination block osteoblast differentiation, which correlates with upregulation of Sfrp4, and downregulation of nuclear and cytosolic β-catenin and reduced expression of the Wnt target gene Axin2. Red arrows indicate effects of RAR agonists on mediators of Wnt signalling.

  10. Insulin Signaling in Liver and Adipose Tissues in Periparturient Dairy Cows Supplemented with Dietary Nicotinic Acid.

    Kinoshita, Asako; Kenéz, Ákos; Locher, Lena; Meyer, Ulrich; Dänicke, Sven; Rehage, Jürgen; Huber, Korinna

    2016-01-01

    The glucose homeostasis in dairy cattle is very well controlled, in line with the metabolic adaptation during the periparturient period. Former studies showed that nicotinic acid (NA) lowered plasma non-esterified fatty acids (NEFA) concentrations and increased insulin sensitivity in dairy cows. Thus, the purpose of this study was to investigate whether the expression of proteins involved in hepatic and adipose insulin signaling and protein expression of hepatic glucose transporter 2 (GLUT2) were affected by dietary NA and dietary concentrate intake in periparturient dairy cows. Twenty pluriparous German Holstein cows were fed with the same diet from about 21 days before the expected calving date (d-21) to calving. After calving, cows were randomly assigned in 4 groups and fed with diets different in concentrate proportion ("HC" with 60:40% or "LC" with 30:70% concentrate-to-roughage ratio) and supplemented with NA (24 g/day) (NA) or without (CON) until d21. Biopsy samples were taken from the liver, subcutaneous (SCAT) and retroperitoneal (RPAT) adipose tissues at d-21 and d21. Protein expression of insulin signaling molecules (insulin receptor (INSR), phosphatidylinositol-3-kinase (PI3K), protein kinase Cζ (PKCζ)) and hepatic GLUT2 was measured by Western Blotting. The ratio of protein expression at d21/at d-21 was calculated and statistically evaluated for the effects of time and diet. Cows in HC had significantly higher dietary energy intake than cows in LC. In RPAT a decrease in PI3K and PKCζ expression was found in all groups, irrespectively of diet. In the liver, the GLUT2 expression was significantly lower in cows in NA compared with cows in CON. In conclusion, insulin signaling might be decreased in RPAT over time without any effect of diet. NA was able to modulate hepatic GLUT2 expression, but its physiological role is unclear.

  11. Insulin Signaling in Liver and Adipose Tissues in Periparturient Dairy Cows Supplemented with Dietary Nicotinic Acid.

    Asako Kinoshita

    Full Text Available The glucose homeostasis in dairy cattle is very well controlled, in line with the metabolic adaptation during the periparturient period. Former studies showed that nicotinic acid (NA lowered plasma non-esterified fatty acids (NEFA concentrations and increased insulin sensitivity in dairy cows. Thus, the purpose of this study was to investigate whether the expression of proteins involved in hepatic and adipose insulin signaling and protein expression of hepatic glucose transporter 2 (GLUT2 were affected by dietary NA and dietary concentrate intake in periparturient dairy cows. Twenty pluriparous German Holstein cows were fed with the same diet from about 21 days before the expected calving date (d-21 to calving. After calving, cows were randomly assigned in 4 groups and fed with diets different in concentrate proportion ("HC" with 60:40% or "LC" with 30:70% concentrate-to-roughage ratio and supplemented with NA (24 g/day (NA or without (CON until d21. Biopsy samples were taken from the liver, subcutaneous (SCAT and retroperitoneal (RPAT adipose tissues at d-21 and d21. Protein expression of insulin signaling molecules (insulin receptor (INSR, phosphatidylinositol-3-kinase (PI3K, protein kinase Cζ (PKCζ and hepatic GLUT2 was measured by Western Blotting. The ratio of protein expression at d21/at d-21 was calculated and statistically evaluated for the effects of time and diet. Cows in HC had significantly higher dietary energy intake than cows in LC. In RPAT a decrease in PI3K and PKCζ expression was found in all groups, irrespectively of diet. In the liver, the GLUT2 expression was significantly lower in cows in NA compared with cows in CON. In conclusion, insulin signaling might be decreased in RPAT over time without any effect of diet. NA was able to modulate hepatic GLUT2 expression, but its physiological role is unclear.

  12. Signaling-sensitive amino acids surround the allosteric ligand binding site of the thyrotropin receptor.

    Kleinau, Gunnar; Haas, Ann-Karin; Neumann, Susanne; Worth, Catherine L; Hoyer, Inna; Furkert, Jens; Rutz, Claudia; Gershengorn, Marvin C; Schülein, Ralf; Krause, Gerd

    2010-07-01

    The thyrotropin receptor [thyroid-stimulating hormone receptor (TSHR)], a G-protein-coupled receptor (GPCR), is endogenously activated by thyrotropin, which binds to the extracellular region of the receptor. We previously identified a low-molecular-weight (LMW) agonist of the TSHR and predicted its allosteric binding pocket within the receptor's transmembrane domain. Because binding of the LMW agonist probably disrupts interactions or leads to formation of new interactions among amino acid residues surrounding the pocket, we tested whether mutation of residues at these positions would lead to constitutive signaling activity. Guided by molecular modeling, we performed site-directed mutagenesis of 24 amino acids in this spatial region, followed by functional characterization of the mutant receptors in terms of expression and signaling, measured as cAMP accumulation. We found that mutations V421I, Y466A, T501A, L587V, M637C, M637W, S641A, Y643F, L645V, and Y667A located in several helices exhibit constitutive activity. Of note is mutation M637W at position 6.48 in transmembrane helix 6, which has a significant effect on the interaction of the receptor with the LMW agonist. In summary, we found that a high proportion of residues in several helices surrounding the allosteric binding site of LMW ligands in the TSHR when mutated lead to constitutively active receptors. Our findings of signaling-sensitive residues in this region of the transmembrane bundle may be of general importance as this domain appears to be evolutionarily retained among GPCRs.

  13. Oridonin stabilizes retinoic acid receptor alpha through ROS-activated NF-κB signaling.

    Cao, Yang; Wei, Wei; Zhang, Nan; Yu, Qing; Xu, Wen-Bin; Yu, Wen-Jun; Chen, Guo-Qiang; Wu, Ying-Li; Yan, Hua

    2015-04-10

    Retinoic acid receptor alpha (RARα) plays an essential role in the regulation of many biological processes, such as hematopoietic cell differentiation, while abnormal RARα function contributes to the pathogenesis of certain diseases including cancers, especially acute promyelocytic leukemia (APL). Recently, oridonin, a natural diterpenoid isolated from Rabdosia rubescens, was demonstrated to regulate RARα by increasing its protein level. However, the underlying molecular mechanism for this action has not been fully elucidated. In the APL cell line, NB4, the effect of oridonin on RARα protein was analyzed by western blot and real-time quantitative RT-PCR analyses. Flow cytometry was performed to detect intracellular levels of reactive oxygen species (ROS). The association between nuclear factor-kappa B (NF-κB) signaling and the effect of oridonin was assessed using specific inhibitors, shRNA gene knockdown, and immunofluorescence assays. In addition, primary leukemia cells were treated with oridonin and analyzed by western blot in this study. RARα possesses transcriptional activity in the presence of its ligand, all-trans retinoic acid (ATRA). Oridonin remarkably stabilized the RARα protein, which retained transcriptional activity. Oridonin also moderately increased intracellular ROS levels, while pretreatment with the ROS scavenger, N-acetyl-l-cysteine (NAC), dramatically abrogated RARα stabilization by oridonin. More intriguingly, direct exposure to low concentrations of H2O2 also increased RARα protein but not mRNA levels, suggesting a role for ROS in oridonin stabilization of RARα protein. Further investigations showed that NAC antagonized oridonin-induced activation of NF-κB signaling, while the NF-κB signaling inhibitor, Bay 11-7082, effectively blocked the oridonin increase in RARα protein levels. In line with this, over-expression of IκΒα (A32/36), a super-repressor form of IκΒα, or NF-κB-p65 knockdown inhibited oridonin or H2O2-induced

  14. Branched-chain amino acids in metabolic signalling and insulin resistance

    Lynch, Christopher J.; Adams, Sean H.

    2015-01-01

    Branched-chain amino acids (BCAAs) are important nutrient signals that have direct and indirect effects. Frequently, BCAAs have been reported to mediate antiobesity effects, especially in rodent models. However, circulating levels of BCAAs tend to be increased in individuals with obesity and are associated with worse metabolic health and future insulin resistance or type 2 diabetes mellitus (T2DM). A hypothesized mechanism linking increased levels of BCAAs and T2DM involves leucine-mediated activation of the mammalian target of rapamycin complex 1 (mTORC1), which results in uncoupling of insulin signalling at an early stage. A BCAA dysmetabolism model proposes that the accumulation of mitotoxic metabolites (and not BCAAs per se) promotes β-cell mitochondrial dysfunction, stress signalling and apoptosis associated with T2DM. Alternatively, insulin resistance might promote aminoacidaemia by increasing the protein degradation that insulin normally suppresses, and/or by eliciting an impairment of efficient BCAA oxidative metabolism in some tissues. Whether and how impaired BCAA metabolism might occur in obesity is discussed in this Review. Research on the role of individual and model-dependent differences in BCAA metabolism is needed, as several genes (BCKDHA, PPM1K, IVD and KLF15) have been designated as candidate genes for obesity and/or T2DM in humans, and distinct phenotypes of tissue-specific branched chain ketoacid dehydrogenase complex activity have been detected in animal models of obesity and T2DM. PMID:25287287

  15. Retinoic acid signaling in B-cells is essential for oral immunization and microflora composition

    Pantazi, Eirini; Marks, Ellen; Stolarczyk, Emilie; Lycke, Nils; Noelle, Randolph J.; Elgueta, Raul

    2015-01-01

    Retinoic acid (RA)3 is a critical regulator of the intestinal adaptive immune response. However, the intrinsic impact of RA on B cell differentiation in the regulation of gut humoral immunity in vivo has never been directly shown. To address this issue, we have been able to generate a mouse model where B-cells specifically express a dominant negative receptor α for RA. Here, we show that the silencing of RA signaling in B-cells reduces the numbers of IgA+ antibody secreting cells (ASC) both in vitro and in vivo, suggesting that RA has a direct effect on IgA plasma cell (PC) differentiation. Moreover, the lack of RA signaling in B-cells abrogates Ag-specific IgA responses after oral immunization and affects the microbiota composition. In conclusion, these results suggest that RA signaling in B-cells through the RA receptor α is important to generate an effective gut humoral response and to maintain a normal microbiota composition. PMID:26163586

  16. Cutting Edge: Retinoic Acid Signaling in B Cells Is Essential for Oral Immunization and Microflora Composition.

    Pantazi, Eirini; Marks, Ellen; Stolarczyk, Emilie; Lycke, Nils; Noelle, Randolph J; Elgueta, Raul

    2015-08-15

    Retinoic acid (RA) is a critical regulator of the intestinal adaptive immune response. However, the intrinsic impact of RA on B cell differentiation in the regulation of gut humoral immunity in vivo has never been directly shown. To address this issue, we have been able to generate a mouse model where B cells specifically express a dominant-negative receptor α for RA. In this study, we show that the silencing of RA signaling in B cells reduces the numbers of IgA(+) Ab-secreting cells both in vitro and in vivo, suggesting that RA has a direct effect on IgA plasma cell differentiation. Moreover, the lack of RA signaling in B cells abrogates Ag-specific IgA responses after oral immunization and affects the microbiota composition. In conclusion, these results suggest that RA signaling in B cells through the RA receptor α is important to generate an effective gut humoral response and to maintain a normal microbiota composition. Copyright © 2015 by The American Association of Immunologists, Inc.

  17. Retinoic acid functions as a key GABAergic differentiation signal in the basal ganglia.

    Christina Chatzi

    2011-04-01

    Full Text Available Although retinoic acid (RA has been implicated as an extrinsic signal regulating forebrain neurogenesis, the processes regulated by RA signaling remain unclear. Here, analysis of retinaldehyde dehydrogenase mutant mouse embryos lacking RA synthesis demonstrates that RA generated by Raldh3 in the subventricular zone of the basal ganglia is required for GABAergic differentiation, whereas RA generated by Raldh2 in the meninges is unnecessary for development of the adjacent cortex. Neurospheres generated from the lateral ganglionic eminence (LGE, where Raldh3 is highly expressed, produce endogenous RA, which is required for differentiation to GABAergic neurons. In Raldh3⁻/⁻ embryos, LGE progenitors fail to differentiate into either GABAergic striatal projection neurons or GABAergic interneurons migrating to the olfactory bulb and cortex. We describe conditions for RA treatment of human embryonic stem cells that result in efficient differentiation to a heterogeneous population of GABAergic interneurons without the appearance of GABAergic striatal projection neurons, thus providing an in vitro method for generation of GABAergic interneurons for further study. Our observation that endogenous RA is required for generation of LGE-derived GABAergic neurons in the basal ganglia establishes a key role for RA signaling in development of the forebrain.

  18. Single amino acid change in STING leads to constitutive active signaling.

    Eric D Tang

    Full Text Available The production of cytokines by the immune system in response to cytosolic DNA plays an important role in host defense, autoimmune disease, and cancer immunogenicity. Recently a cytosolic DNA signaling pathway that is dependent on the endoplasmic reticulum adaptor and cyclic dinucleotide sensor protein STING has been identified. Association of cytosolic DNA with cyclic-GMP-AMP synthase (cGAS activates its enzymatic activity to synthesize the cyclic dinucleotide second messenger cGAMP from GTP and ATP. Direct detection of cGAMP by STING triggers the activation of IRF3 and NF-kB, and the production of type I interferons and proinflammatory cytokines. The mechanism of how STING is able to mediate downstream signaling remains incompletely understood although it has been shown that dimerization is a prerequisite. Here, we identify a single amino acid change in STING that confers constitutive active signaling. This mutation appears to both enhance ability of STING to both dimerize and associate with its downstream target TBK1.

  19. Single amino acid change in STING leads to constitutive active signaling.

    Tang, Eric D; Wang, Cun-Yu

    2015-01-01

    The production of cytokines by the immune system in response to cytosolic DNA plays an important role in host defense, autoimmune disease, and cancer immunogenicity. Recently a cytosolic DNA signaling pathway that is dependent on the endoplasmic reticulum adaptor and cyclic dinucleotide sensor protein STING has been identified. Association of cytosolic DNA with cyclic-GMP-AMP synthase (cGAS) activates its enzymatic activity to synthesize the cyclic dinucleotide second messenger cGAMP from GTP and ATP. Direct detection of cGAMP by STING triggers the activation of IRF3 and NF-kB, and the production of type I interferons and proinflammatory cytokines. The mechanism of how STING is able to mediate downstream signaling remains incompletely understood although it has been shown that dimerization is a prerequisite. Here, we identify a single amino acid change in STING that confers constitutive active signaling. This mutation appears to both enhance ability of STING to both dimerize and associate with its downstream target TBK1.

  20. Coregulation of Soybean Vegetative Storage Protein Gene Expression by Methyl Jasmonate and Soluble Sugars 1

    Mason, Hugh S.; DeWald, Daryll B.; Creelman, Robert A.; Mullet, John E.

    1992-01-01

    The soybean vegetative storage protein genes vspA and vspB are highly expressed in developing leaves, stems, flowers, and pods as compared with roots, seeds, and mature leaves and stems. In this paper, we report that physiological levels of methyl jasmonate (MeJA) and soluble sugars synergistically stimulate accumulation of vsp mRNAs. Treatment of excised mature soybean (Glycine max Merr. cv Williams) leaves with 0.2 molar sucrose and 10 micromolar MeJA caused a large accumulation of vsp mRNAs, whereas little accumulation occurred when these compounds were supplied separately. In soybean cell suspension cultures, the synergistic effect of sucrose and MeJA on the accumulation of vspB mRNA was maximal at 58 millimolar sucrose and was observed with fructose or glucose substituted for sucrose. In dark-grown soybean seedlings, the highest levels of vsp mRNAs occurred in the hypocotyl hook, which also contained high levels of MeJA and soluble sugars. Lower levels of vsp mRNAs, MeJA, and soluble sugars were found in the cotyledons, roots, and nongrowing regions of the stem. Wounding of mature soybean leaves induced a large accumulation of vsp mRNAs when wounded plants were incubated in the light. Wounded plants kept in the dark or illuminated plants sprayed with dichlorophenyldimethylurea, an inhibitor of photosynthetic electron transport, showed a greatly reduced accumulation of vsp mRNAs. The time courses for the accumulation of vsp mRNAs induced by wounding or sucrose/MeJA treatment were similar. These results strongly suggest that vsp expression is coregulated by endogenous levels of MeJA (or jasmonic acid) and soluble carbohydrate during normal vegetative development and in wounded leaves. ImagesFigure 1Figure 4Figure 5 PMID:16668757

  1. Coregulation of soybean vegetative storage protein gene expression by methyl jasmonate and soluble sugars.

    Mason, H S; Dewald, D B; Creelman, R A; Mullet, J E

    1992-03-01

    The soybean vegetative storage protein genes vspA and vspB are highly expressed in developing leaves, stems, flowers, and pods as compared with roots, seeds, and mature leaves and stems. In this paper, we report that physiological levels of methyl jasmonate (MeJA) and soluble sugars synergistically stimulate accumulation of vsp mRNAs. Treatment of excised mature soybean (Glycine max Merr. cv Williams) leaves with 0.2 molar sucrose and 10 micromolar MeJA caused a large accumulation of vsp mRNAs, whereas little accumulation occurred when these compounds were supplied separately. In soybean cell suspension cultures, the synergistic effect of sucrose and MeJA on the accumulation of vspB mRNA was maximal at 58 millimolar sucrose and was observed with fructose or glucose substituted for sucrose. In dark-grown soybean seedlings, the highest levels of vsp mRNAs occurred in the hypocotyl hook, which also contained high levels of MeJA and soluble sugars. Lower levels of vsp mRNAs, MeJA, and soluble sugars were found in the cotyledons, roots, and nongrowing regions of the stem. Wounding of mature soybean leaves induced a large accumulation of vsp mRNAs when wounded plants were incubated in the light. Wounded plants kept in the dark or illuminated plants sprayed with dichlorophenyldimethylurea, an inhibitor of photosynthetic electron transport, showed a greatly reduced accumulation of vsp mRNAs. The time courses for the accumulation of vsp mRNAs induced by wounding or sucrose/MeJA treatment were similar. These results strongly suggest that vsp expression is coregulated by endogenous levels of MeJA (or jasmonic acid) and soluble carbohydrate during normal vegetative development and in wounded leaves.

  2. Exogenous application of the plant signalers methyl jasmonate & salicylic acid induces changes in volatile emissions from citrus foliage & influences the aggregation behavior of ACP (Diaphorina citri), vector of Huanglongbing

    Huanglongbing or citrus greening is a destructive disease that threatens citrus production worldwide; it is putatively caused by the phloem-limited bacterium Candidatus Liberibacter asiaticus (Las). Currently the disease is untreatable and control efforts focus on intensive insecticide use to contro...

  3. Raman database of amino acids solutions: A critical study of Extended Multiplicative Signal Correction

    Candeloro, Patrizio

    2013-01-01

    The Raman spectra of biological materials always exhibit complex profiles, constituting several peaks and/or bands which arise due to the large variety of biomolecules. The extraction of quantitative information from these spectra is not a trivial task. While qualitative information can be retrieved from the changes in peaks frequencies or from the appearance/disappearance of some peaks, quantitative analysis requires an examination of peak intensities. Unfortunately in biological samples it is not easy to identify a reference peak for normalizing intensities, and this makes it very difficult to study the peak intensities. In the last decades a more refined mathematical tool, the extended multiplicative signal correction (EMSC), has been proposed for treating infrared spectra, which is also capable of providing quantitative information. From the mathematical and physical point of view, EMSC can also be applied to Raman spectra, as recently proposed. In this work the reliability of the EMSC procedure is tested by application to a well defined biological system: the 20 standard amino acids and their combination in peptides. The first step is the collection of a Raman database of these 20 amino acids, and subsequently EMSC processing is applied to retrieve quantitative information from amino acids mixtures and peptides. A critical review of the results is presented, showing that EMSC has to be carefully handled for complex biological systems. © 2013 The Royal Society of Chemistry.

  4. Two zebrafish G2A homologs activate multiple intracellular signaling pathways in acidic environment

    Ichijo, Yuta; Mochimaru, Yuta [Laboratory of Cell Signaling Regulation, Department of Life Sciences, School of Agriculture, Meiji University, Kawasaki 214-8571 (Japan); Azuma, Morio [Laboratory of Regulatory Biology, Graduate School of Science and Engineering, University of Toyama, 3190-Gofuku, Toyama 930-8555 (Japan); Satou, Kazuhiro; Negishi, Jun [Laboratory of Cell Signaling Regulation, Department of Life Sciences, School of Agriculture, Meiji University, Kawasaki 214-8571 (Japan); Nakakura, Takashi [Department of Anatomy, Graduate School of Medicine, Teikyo University, 2-11-1 Itabashi-Ku, Tokyo 173-8605 (Japan); Oshima, Natsuki [Laboratory of Cell Signaling Regulation, Department of Life Sciences, School of Agriculture, Meiji University, Kawasaki 214-8571 (Japan); Mogi, Chihiro; Sato, Koichi [Laboratory of Signal Transduction, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi 371-8512 (Japan); Matsuda, Kouhei [Laboratory of Regulatory Biology, Graduate School of Science and Engineering, University of Toyama, 3190-Gofuku, Toyama 930-8555 (Japan); Okajima, Fumikazu [Laboratory of Signal Transduction, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi 371-8512 (Japan); Tomura, Hideaki, E-mail: tomurah@meiji.ac.jp [Laboratory of Cell Signaling Regulation, Department of Life Sciences, School of Agriculture, Meiji University, Kawasaki 214-8571 (Japan)

    2016-01-01

    Human G2A is activated by various stimuli such as lysophosphatidylcholine (LPC), 9-hydroxyoctadecadienoic acid (9-HODE), and protons. The receptor is coupled to multiple intracellular signaling pathways, including the G{sub s}-protein/cAMP/CRE, G{sub 12/13}-protein/Rho/SRE, and G{sub q}-protein/phospholipase C/NFAT pathways. In the present study, we examined whether zebrafish G2A homologs (zG2A-a and zG2A-b) could respond to these stimuli and activate multiple intracellular signaling pathways. We also examined whether histidine residue and basic amino acid residue in the N-terminus of the homologs also play roles similar to those played by human G2A residues if the homologs sense protons. We found that the zG2A-a showed the high CRE, SRE, and NFAT activities, however, zG2A-b showed only the high SRE activity under a pH of 8.0. Extracellular acidification from pH 7.4 to 6.3 ameliorated these activities in zG2A-a-expressing cells. On the other hand, acidification ameliorated the SRE activity but not the CRE and NFAT activities in zG2A-b-expressing cells. LPC or 9-HODE did not modify any activity of either homolog. The substitution of histidine residue at the 174{sup th} position from the N-terminus of zG2A-a to asparagine residue attenuated proton-induced CRE and NFAT activities but not SRE activity. The substitution of arginine residue at the 32nd position from the N-terminus of zG2A-a to the alanine residue also attenuated its high and the proton-induced CRE and NFAT activities. On the contrary, the substitution did not attenuate SRE activity. The substitution of the arginine residue at the 10th position from the N-terminus of zG2A-b to the alanine residue also did not attenuate its high or the proton-induced SRE activity. These results indicate that zebrafish G2A homologs were activated by protons but not by LPC and 9-HODE, and the activation mechanisms of the homologs were similar to those of human G2A. - Highlights: • Zebrafish two G2A homologs are proton

  5. Methyl jasmonate induced resistance in cheniere rice and soybean plants

    Taplin, C.

    2017-12-01

    Methyl jasmonate (MJ) is a compound naturally occurring in certain plants that aids in plant defense. In this study, we examined the difference in herbivory of fall armyworm (FAW) on control plants (treated without MJ) and MJ-treated plants. Seeds of cheniere rice and soybean were soaked in MJ overnight and planted in the greenhouse, although the soybean never grew. Therefore, only the mature plant leaves of cheniere rice were fed to FAW and the difference in herbivory was looked at. Our results show there is no statistical difference in the herbivory of the cheniere rice plant leaves.

  6. Ferulic acid attenuates diabetes-induced cognitive impairment in rats via regulation of PTP1B and insulin signaling pathway.

    Wang, Hao; Sun, Xiaoxu; Zhang, Ning; Ji, Zhouye; Ma, Zhanqiang; Fu, Qiang; Qu, Rong; Ma, Shiping

    2017-12-01

    Cognitive impairment has been recognized as a typical characteristic of neurodegenerative disease in diabetes mellitus (DM) and this cognitive dysfunction may be a risk factor for Alzheimer's disease (AD). Ferulic acid, a phenolic compound commonly found in a range of plants, has emerged various properties including anti-inflammatory and neuroprotective effects. In the present study, the protective activities and relevant mechanisms of ferulic acid were evaluated in diabetic rats with cognitive deficits, which were induced by a high-glucose-fat (HGF) diet and low dose of streptozotocin (STZ). It was observed that ferulic acid significantly increased body weight and decreased blood glucose levels. Meanwhile, ferulic acid could markedly ameliorate spatial memory of diabetic rats in Morris water maze (MWM) and decrease AD-like pathologic changes (Aβ deposition and Tau phosphorylation) in the hippocampus, which might be correlated with the inhibition of inflammatory cytokines release and reduction of protein tyrosine phosphatase 1B (PTP1B) expression. Moreover, the levels of brain insulin signal molecules p-IRS, p-Akt and p-GSK3β were also investigated. We found that ferulic acid administration restored the alterations in insulin signaling. In conclusion, ferulic acid exhibited beneficial effects on diabetes-induced cognition lesions, which was involved in the regulation of PTP1B and insulin signaling pathway. We suppose that PTP1B inhibition may represent a promising approach to correct abnormal signaling linked to diabetes-induced cognitive impairment. Copyright © 2017. Published by Elsevier Inc.

  7. The actions of exogenous leucine on mTOR signalling and amino acid transporters in human myotubes

    Cameron-Smith David

    2011-06-01

    Full Text Available Abstract Background The branched-chain amino acid (BCAA leucine has been identified to be a key regulator of skeletal muscle anabolism. Activation of anabolic signalling occurs via the mammalian target of rapamycin (mTOR through an undefined mechanism. System A and L solute carriers transport essential amino acids across plasma membranes; however it remains unknown whether an exogenous supply of leucine regulates their gene expression. The aim of the present study was to investigate the effects of acute and chronic leucine stimulation of anabolic signalling and specific amino acid transporters, using cultured primary human skeletal muscle cells. Results Human myotubes were treated with leucine, insulin or co-treated with leucine and insulin for 30 min, 3 h or 24 h. Activation of mTOR signalling kinases were examined, together with putative nutrient sensor human vacuolar protein sorting 34 (hVps34 and gene expression of selected amino acid transporters. Phosphorylation of mTOR and p70S6K was transiently increased following leucine exposure, independently to insulin. hVps34 protein expression was also significantly increased. However, genes encoding amino acid transporters were differentially regulated by insulin and not leucine. Conclusions mTOR signalling is transiently activated by leucine within human myotubes independently of insulin stimulation. While this occurred in the absence of changes in gene expression of amino acid transporters, protein expression of hVps34 increased.

  8. OPDA-Ile a new JA-Ile-independent signal?

    Wasternack, Claus; Hause, B.

    2016-01-01

    Roč. 11, č. 11 (2016), č. článku e1253646. ISSN 1559-2316 R&D Projects: GA MŠk(CZ) LO1204; GA ČR GA14-34792S Institutional support: RVO:61389030 Keywords : allene oxide cyclase * 12-oxo-phytodienoic acid * arabidopsis -thaliana * stress responses * jasmonic acid * cyclopentenones * perception * coronatine * repressors * oxylipins * 12-oxo-phytodienoic acid (OPDA) * JA-Ile perception * jasmonic acid (JA) * jasmonoyl-isoleucine (JA-Ile) * OPDA-Ile-induced gene expression * SCFCOI1-JAZ coreceptor complex Subject RIV: EB - Genetics ; Molecular Biology

  9. Mechanistic Basis for Plant Responses to Drought Stress : Regulatory Mechanism of Abscisic Acid Signaling

    Miyakawa, Takuya; Tanokura, Masaru

    The phytohormone abscisic acid (ABA) plays a key role in the rapid adaptation of plants to environmental stresses such as drought and high salinity. Accumulated ABA in plant cells promotes stomatal closure in guard cells and transcription of stress-tolerant genes. Our understanding of ABA responses dramatically improved by the discovery of both PYR/PYL/RCAR as a soluble ABA receptor and inhibitory complex of a protein phospatase PP2C and a protein kinase SnRK2. Moreover, several structural analyses of PYR/PYL/RCAR revealed the mechanistic basis for the regulatory mechanism of ABA signaling, which provides a rational framework for the design of alternative agonists in future.

  10. 9-Hydroxystearic acid interferes with EGF signalling in a human colon adenocarcinoma

    Calonghi, Natalia; Pagnotta, Eleonora; Parolin, Carola; Tognoli, Cristina; Boga, Carla; Masotti, Lanfranco

    2006-01-01

    The epidermal growth factor has long been known to be strictly correlated with the highly proliferating activities of cancer cells and primary tumors. Moreover, in the nucleus, the epidermal growth factor/epidermal growth factor receptor complex (EGF/EGFR) functions as a transcriptional regulator that activates the cyclin D1 gene. 9-hydroxystearic acid (9-HSA) induces cell proliferation arrest and differentiation in HT29 colon cancer cells by inhibiting histone deacetylase 1 (HDAC1). 9-HSA-treated HT29, when stimulated with EGF, are not responsive and surprisingly undergo a further arrest. In order to understand the mechanisms of this effect, we analyzed the degree of internalization of the EGF/EGFR complex and its interactions with HDAC1. It appears that HDAC1, as modified by 9-HSA, is unable to associate with cyclin D1, interfering with the cell proliferation program, and sequesters the EGF/EGFR complex interrupting the transduction of the mitogenic signal

  11. Retinol dehydrogenase-10 regulates pancreas organogenesis and endocrine cell differentiation via paracrine retinoic acid signalling

    Arregi, Igor; Climent, Maria; Iliev, Dobromir

    2016-01-01

    Vitamin A-derived retinoic acid (RA) signals are critical for the development of several organs, including the pancreas. However, the tissue-specific control of RA synthesis in organ and cell lineage development has only poorly been addressed in vivo. Here we show that Retinol dehydrogenase-10 (Rdh......10), a key enzyme in embryonic RA production, has important functions in pancreas organogenesis and endocrine cell differentiation. Rdh10 was expressed in the developing pancreas epithelium and surrounding mesenchyme. Rdh10 null mutant mouse embryos exhibited dorsal pancreas agenesis...... and a hypoplastic ventral pancreas with retarded tubulogenesis and branching. Conditional disruption of Rdh10 from the endoderm caused increased mortality, reduced body weight and lowered blood glucose levels after birth. Endodermal Rdh10 deficiency led to a smaller dorsal pancreas with a reduced density of early...

  12. Arbuscular mycorrhizal symbiosis and methyl jasmonate avoid the inhibition of root hydraulic conductivity caused by drought.

    Sánchez-Romera, Beatriz; Ruiz-Lozano, Juan Manuel; Zamarreño, Ángel María; García-Mina, José María; Aroca, Ricardo

    2016-02-01

    Hormonal regulation and symbiotic relationships provide benefits for plants to overcome stress conditions. The aim of this study was to elucidate the effects of exogenous methyl jasmonate (MeJA) application on root hydraulic conductivity (L) of Phaseolus vulgaris plants which established arbuscular mycorrhizal (AM) symbiosis under two water regimes (well-watered and drought conditions). The variation in endogenous contents of several hormones (MeJA, JA, abscisic acid (ABA), indol-3-acetic acid (IAA), salicylic acid (SA)) and the changes in aquaporin gene expression, protein abundance and phosphorylation state were analyzed. AM symbiosis decreased L under well-watered conditions, which was partially reverted by the MeJA treatment, apparently by a drop in root IAA contents. Also, AM symbiosis and MeJA prevented inhibition of L under drought conditions, most probably by a reduction in root SA contents. Additionally, the gene expression of two fungal aquaporins was upregulated under drought conditions, independently of the MeJA treatment. Plant aquaporin gene expression could not explain the behaviour of L. Conversely, evidence was found for the control of L by phosphorylation of aquaporins. Hence, MeJA addition modified the response of L to both AM symbiosis and drought, presumably by regulating the root contents of IAA and SA and the phosphorylation state of aquaporins.

  13. Age-related Resistance and the Defense Signaling Pathway of Ph-3 Gene Against Phytophthora infestans in Tomatoes

    Sayed Rashad Ali Shah

    2015-09-01

    Full Text Available Resistance (R genes against plant pathogens often have age-related resistance (ARR effects. However, the mechanism involved in this phenomenon remains unknown. In this paper, Solanum lycopersicum ‘CLN2037B’ and S. pimpinellifolium ‘L3708’ harboring the Ph-3 gene, as well as S. habrochaites ‘LA2099’, ‘LA1777’ and ‘LA1033’ harboring quantitative trait loci (QTLs, were tested to investigate age-related resistance against late blight (LB; caused by Phytophthora infestans in the three-leaf stage of the plants. The results demonstrated that the QTL-related LB resistance showed the same age-related resistance as the Ph-3-mediated resistance at the six- and nine-leaf stages compared with the three-leaf stage. This indicated that there is a common defense mechanism in tomatoes against P. infestans via ARR. In addition, we combined ethylene (ET, salicylic acid (SA and jasmonic acid (JA mutants with virus-induced gene silencing (VIGS to study the Ph-3-dependent resistance signaling pathway. The results showed that ethylene and salicylic acid, but not jasmonic acid, are involved in the LB resistance mediated by the Ph-3 gene.

  14. The pivotal role of abscisic acid signaling during transition from seed maturation to germination.

    Yan, An; Chen, Zhong

    2017-05-01

    Seed maturation and germination are two continuous developmental processes that link two distinct generations in spermatophytes; the precise genetic control of these two processes is, therefore, crucially important for the survival of the next generation. Pieces of experimental evidence accumulated so far indicate that a concerted action of endogenous signals and environmental cues is required to govern these processes. Plant hormone abscisic acid (ABA) has been suggested to play a predominant role in directing seed maturation and maintaining seed dormancy under unfavorable environmental conditions until antagonized by gibberellins (GA) and certain environmental cues to allow the commencement of seed germination when environmental conditions are favorable; therefore, the balance of ABA and GA is a major determinant of the timing of seed germination. Due to the advent of new technologies and system biology approaches, molecular studies are beginning to draw a picture of the sophisticated genetic network that drives seed maturation during the past decade, though the picture is still incomplete and many details are missing. In this review, we summarize recent advances in ABA signaling pathway in the regulation of seed maturation as well as the transition from seed maturation to germination, and highlight the importance of system biology approaches in the study of seed maturation.

  15. Streptozotocin induced activation of oxidative stress responsive splenic cell signaling pathways: Protective role of arjunolic acid

    Manna, Prasenjit; Ghosh, Jyotirmoy; Das, Joydeep; Sil, Parames C.

    2010-01-01

    Present study investigates the beneficial role of arjunolic acid (AA) against the alteration in the cytokine levels and simultaneous activation of oxidative stress responsive signaling pathways in spleen under hyperglycemic condition. Diabetes was induced by injection of streptozotocin (STZ) (at a dose of 70 mg/kg body weight, injected in the tail vain). STZ administration elevated the levels of IL-2 as well as IFN-γ and attenuated the level of TNF-α in the sera of diabetic animals. In addition, hyperglycemia is also associated with the increased production of intracellular reactive intermediates resulting with the elevation in lipid peroxidation, protein carbonylation and reduction in intracellular antioxidant defense. Investigating the oxidative stress responsive cell signaling pathways, increased expressions (immunoreactive concentrations) of phosphorylated p65 as well as its inhibitor protein phospho IκBα and phosphorylated mitogen activated protein kinases (MAPKs) have been observed in diabetic spleen tissue. Studies on isolated splenocytes revealed that hyperglycemia caused disruption of mitochondrial membrane potential, elevation in the concentration of cytosolic cytochrome c as well as activation of caspase 3 leading to apoptotic cell death. Histological examination revealed that diabetic induction depleted the white pulp scoring which is in agreement with the reduced immunological response. Treatment with AA prevented the hyperglycemia and its associated pathogenesis in spleen tissue. Results suggest that AA might act as an anti-diabetic and immunomodulatory agent against hyperglycemia.

  16. Ternary Surface Monolayers for Ultrasensitive (Zeptomole) Amperometric Detection of Nucleic-Acid Hybridization without Signal Amplification

    Wu, Jie; Campuzano, Susana; Halford, Colin; Haake, David A.; Wang, Joseph

    2010-01-01

    A ternary surface monolayer, consisting of co-assembled thiolated capture probe (SHCP) mercaptohexanol (MCH) and dithiothreitol (DTT), is shown to offer dramatic improvements in the signal-to-noise characteristics of electrochemical DNA hybridization biosensors based on common self-assembled monolayers (SAMs). Remarkably low detection limits down to 40 zmole (in 4 μL samples) as well as only 1 CFU E. coli per sensor are thus obtained without any additional amplification step in connection to the commonly used horseradish peroxidase/3,3′,5,5′-tetramethylbenzidine (HRP/TMB) system. Such dramatic improvements in the detection limits (compared to common binary alkanethiol interfaces and to most electrochemical DNA sensing strategies without target or signal amplification) are attributed primarily to the remarkably higher resistance to non-specific adsorption. This reflects the highly compact layer (with lower pinhole density) produced by the coupling of the cyclic- and linear-configuration ‘backfillers’ that leads to a remarkably low background noise even in the presence of complex sample matrices. A wide range of surface compositions have been investigated and the ternary mixed monolayer has been systematically optimized. Detailed impedance spectroscopy and cyclic voltammetric studies shed useful insights into the surface coverage. The impressive sensitivity and high specificity of the simple developed methodology indicate great promise for a wide range of nucleic acid testing, including clinical diagnostics, biothreat detection, food safety and forensic analysis. PMID:20883023

  17. Ternary surface monolayers for ultrasensitive (zeptomole) amperometric detection of nucleic acid hybridization without signal amplification.

    Wu, Jie; Campuzano, Susana; Halford, Colin; Haake, David A; Wang, Joseph

    2010-11-01

    A ternary surface monolayer, consisting of coassembled thiolated capture probe, mercaptohexanol and dithiothreitol, is shown to offer dramatic improvements in the signal-to-noise characteristics of electrochemical DNA hybridization biosensors based on common self-assembled monolayers. Remarkably low detection limits down to 40 zmol (in 4 μL samples) as well as only 1 CFU Escherichia coli per sensor are thus obtained without any additional amplification step in connection to the commonly used horseradish peroxidase/3,3',5,5'-tetramethylbenzidine system. Such dramatic improvements in the detection limits (compared to those of common binary alkanethiol interfaces and to those of most electrochemical DNA sensing strategies without target or signal amplification) are attributed primarily to the remarkably higher resistance to nonspecific adsorption. This reflects the highly compact layer (with lower pinhole density) produced by the coupling of the cyclic- and linear-configuration "backfillers" that leads to a remarkably low background noise even in the presence of complex sample matrixes. A wide range of surface compositions have been investigated, and the ternary mixed monolayer has been systematically optimized. Detailed impedance spectroscopy and cyclic voltammetric studies shed useful insights into the surface coverage. The impressive sensitivity and high specificity of the simple developed methodology indicate great promise for a wide range of nucleic acid testing, including clinical diagnostics, biothreat detection, food safety, and forensic analysis.

  18. Transcription factor TLX1 controls retinoic acid signaling to ensure spleen development

    Lenti, Elisa; Farinello, Diego; Penkov, Dmitry; Castagnaro, Laura; Lavorgna, Giovanni; Wuputra, Kenly; Tjaden, Naomi E. Butler; Bernassola, Francesca; Caridi, Nicoletta; Wagner, Michael; Kozinc, Katja; Niederreither, Karen; Blasi, Francesco; Pasini, Diego; Trainor, Paul A.

    2016-01-01

    The molecular mechanisms that underlie spleen development and congenital asplenia, a condition linked to increased risk of overwhelming infections, remain largely unknown. The transcription factor TLX1 controls cell fate specification and organ expansion during spleen development, and Tlx1 deletion causes asplenia in mice. Deregulation of TLX1 expression has recently been proposed in the pathogenesis of congenital asplenia in patients carrying mutations of the gene-encoding transcription factor SF-1. Herein, we have shown that TLX1-dependent regulation of retinoic acid (RA) metabolism is critical for spleen organogenesis. In a murine model, loss of Tlx1 during formation of the splenic anlage increased RA signaling by regulating several genes involved in RA metabolism. Uncontrolled RA activity resulted in premature differentiation of mesenchymal cells and reduced vasculogenesis of the splenic primordium. Pharmacological inhibition of RA signaling in Tlx1-deficient animals partially rescued the spleen defect. Finally, spleen growth was impaired in mice lacking either cytochrome P450 26B1 (Cyp26b1), which results in excess RA, or retinol dehydrogenase 10 (Rdh10), which results in RA deficiency. Together, these findings establish TLX1 as a critical regulator of RA metabolism and provide mechanistic insights into the molecular determinants of human congenital asplenia. PMID:27214556

  19. Ethylene Receptors Signal via a Noncanonical Pathway to Regulate Abscisic Acid Responses1[OPEN

    Bakshi, Arkadipta; Fernandez, Jessica C.

    2018-01-01

    Ethylene is a gaseous plant hormone perceived by a family of receptors in Arabidopsis (Arabidopsis thaliana) including ETHYLENE RESPONSE1 (ETR1) and ETR2. Previously we showed that etr1-6 loss-of-function plants germinate better and etr2-3 loss-of-function plants germinate worse than wild-type under NaCl stress and in response to abscisic acid (ABA). In this study, we expanded these results by showing that ETR1 and ETR2 have contrasting roles in the control of germination under a variety of inhibitory conditions for seed germination such as treatment with KCl, CuSO4, ZnSO4, and ethanol. Pharmacological and molecular biology results support a model where ETR1 and ETR2 are indirectly affecting the expression of genes encoding ABA signaling proteins to affect ABA sensitivity. The receiver domain of ETR1 is involved in this function in germination under these conditions and controlling the expression of genes encoding ABA signaling proteins. Epistasis analysis demonstrated that these contrasting roles of ETR1 and ETR2 do not require the canonical ethylene signaling pathway. To explore the importance of receptor-protein interactions, we conducted yeast two-hybrid screens using the cytosolic domains of ETR1 and ETR2 as bait. Unique interacting partners with either ETR1 or ETR2 were identified. We focused on three of these proteins and confirmed the interactions with receptors. Loss of these proteins led to faster germination in response to ABA, showing that they are involved in ABA responses. Thus, ETR1 and ETR2 have both ethylene-dependent and -independent roles in plant cells that affect responses to ABA. PMID:29158332

  20. Gambogic acid inhibits multiple myeloma mediated osteoclastogenesis through suppression of chemokine receptor CXCR4 signaling pathways.

    Pandey, Manoj K; Kale, Vijay P; Song, Chunhua; Sung, Shen-shu; Sharma, Arun K; Talamo, Giampaolo; Dovat, Sinisa; Amin, Shantu G

    2014-10-01

    Bone disease, characterized by the presence of lytic lesions and osteoporosis is the hallmark of multiple myeloma (MM). Stromal cell-derived factor 1α (SDF-1α) and its receptor, CXC chemokine receptor 4 (CXCR4), has been implicated as a regulator of bone resorption, suggesting that agents that can suppress SDF1α/CXCR4 signaling might inhibit osteoclastogenesis, a process closely linked to bone resorption. We, therefore, investigated whether gambogic acid (GA), a xanthone, could inhibit CXCR4 signaling and suppress osteoclastogenesis induced by MM cells. Through docking studies we predicted that GA directly interacts with CXCR4. This xanthone down-regulates the expression of CXCR4 on MM cells in a dose- and time-dependent manner. The down-regulation of CXCR4 was not due to proteolytic degradation, but rather GA suppresses CXCR4 mRNA expression by inhibiting nuclear factor-kappa B (NF-κB) DNA binding. This was further confirmed by quantitative chromatin immunoprecipitation assay, as GA inhibits p65 binding at the CXCR4 promoter. GA suppressed SDF-1α-induced chemotaxis of MM cells and downstream signaling of CXCR4 by inhibiting phosphorylation of Akt, p38, and Erk1/2 in MM cells. GA abrogated the RANKL-induced differentiation of macrophages to osteoclasts in a dose- and time-dependent manner. In addition, we found that MM cells induced differentiation of macrophages to osteoclasts, and that GA suppressed this process. Importantly, suppression of osteoclastogenesis by GA was mediated through IL-6 inhibition. Overall, our results show that GA is a novel inhibitor of CXCR4 expression and has a strong potential to suppress osteoclastogenesis mediated by MM cells. Published by Elsevier Inc.

  1. Global mapping of protein phosphorylation events identifies novel signalling hubs mediating fatty acid starvation responses in Saccharomyces cerevisiae

    Pultz, Dennis; Bennetzen, Martin; Rødkær, Steven Vestergaard

    2011-01-01

    Dietary restriction (DR) extends the life span of multiple species, ranging from single-celled organisms like yeast to mammals. This increase in longevity by dietary restriction is coupled to profound beneficial effects on age-related pathology. Despite the number of studies on DR...... and the physiological changes DR induces, only little is known about the genetics and signalling networks, which regulate the DR response. We have recently shown that inhibition of fatty acid synthesis in Saccharomyces cerevisiae induces autophagy mediated by TORC1 signalling and affects life span. In the present study...... 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...

  2. The Jasmonate-ZIM-domain proteins interact with the WD-Repeat/bHLH/MYB complexes to regulate Jasmonate-mediated anthocyanin accumulation and trichome initiation in Arabidopsis thaliana.

    Qi, Tiancong; Song, Susheng; Ren, Qingcuo; Wu, Dewei; Huang, Huang; Chen, Yan; Fan, Meng; Peng, Wen; Ren, Chunmei; Xie, Daoxin

    2011-05-01

    Jasmonates (JAs) mediate plant responses to insect attack, wounding, pathogen infection, stress, and UV damage and regulate plant fertility, anthocyanin accumulation, trichome formation, and many other plant developmental processes. Arabidopsis thaliana Jasmonate ZIM-domain (JAZ) proteins, substrates of the CORONATINE INSENSITIVE1 (COI1)-based SCF(COI1) complex, negatively regulate these plant responses. Little is known about the molecular mechanism for JA regulation of anthocyanin accumulation and trichome initiation. In this study, we revealed that JAZ proteins interact with bHLH (Transparent Testa8, Glabra3 [GL3], and Enhancer of Glabra3 [EGL3]) and R2R3 MYB transcription factors (MYB75 and Glabra1), essential components of WD-repeat/bHLH/MYB transcriptional complexes, to repress JA-regulated anthocyanin accumulation and trichome initiation. Genetic and physiological evidence showed that JA regulates WD-repeat/bHLH/MYB complex-mediated anthocyanin accumulation and trichome initiation in a COI1-dependent manner. Overexpression of the MYB transcription factor MYB75 and bHLH factors (GL3 and EGL3) restored anthocyanin accumulation and trichome initiation in the coi1 mutant, respectively. We speculate that the JA-induced degradation of JAZ proteins abolishes the interactions of JAZ proteins with bHLH and MYB factors, allowing the transcriptional function of WD-repeat/bHLH/MYB complexes, which subsequently activate respective downstream signal cascades to modulate anthocyanin accumulation and trichome initiation.

  3. The Jasmonate-ZIM-Domain Proteins Interact with the WD-Repeat/bHLH/MYB Complexes to Regulate Jasmonate-Mediated Anthocyanin Accumulation and Trichome Initiation in Arabidopsis thaliana[C][W

    Qi, Tiancong; Song, Susheng; Ren, Qingcuo; Wu, Dewei; Huang, Huang; Chen, Yan; Fan, Meng; Peng, Wen; Ren, Chunmei; Xie, Daoxin

    2011-01-01

    Jasmonates (JAs) mediate plant responses to insect attack, wounding, pathogen infection, stress, and UV damage and regulate plant fertility, anthocyanin accumulation, trichome formation, and many other plant developmental processes. Arabidopsis thaliana Jasmonate ZIM-domain (JAZ) proteins, substrates of the CORONATINE INSENSITIVE1 (COI1)–based SCFCOI1 complex, negatively regulate these plant responses. Little is known about the molecular mechanism for JA regulation of anthocyanin accumulation and trichome initiation. In this study, we revealed that JAZ proteins interact with bHLH (Transparent Testa8, Glabra3 [GL3], and Enhancer of Glabra3 [EGL3]) and R2R3 MYB transcription factors (MYB75 and Glabra1), essential components of WD-repeat/bHLH/MYB transcriptional complexes, to repress JA-regulated anthocyanin accumulation and trichome initiation. Genetic and physiological evidence showed that JA regulates WD-repeat/bHLH/MYB complex-mediated anthocyanin accumulation and trichome initiation in a COI1-dependent manner. Overexpression of the MYB transcription factor MYB75 and bHLH factors (GL3 and EGL3) restored anthocyanin accumulation and trichome initiation in the coi1 mutant, respectively. We speculate that the JA-induced degradation of JAZ proteins abolishes the interactions of JAZ proteins with bHLH and MYB factors, allowing the transcriptional function of WD-repeat/bHLH/MYB complexes, which subsequently activate respective downstream signal cascades to modulate anthocyanin accumulation and trichome initiation. PMID:21551388

  4. Non-genomic actions of retinoic acid induce pi3k signaling pathway and phosphorylation of nuclear proteins

    Laserna Mendieta, Emilio J.; Masiá, Susana; Barettino, Domingo

    2007-01-01

    Retinoic acid (RA), the active form of vitamin A, induces neuroblastoma cells SH-SY5Y to differentiate. In addition to its classical transcriptional actions regulating the expression of specific genes, RA acts in an extra-genomic way, modulating the activity of relevant signalling cascades. In particular, RA treatment of SH-SY5Y neuroblastoma cells results in activation of phosphatidyl-inositol-3-kinase (PI3K) signaling pathway, and this activation is required for RA-induced differentiation (...

  5. Protein Conformation Ensembles Monitored by HDX Reveal a Structural Rationale for Abscisic Acid Signaling Protein Affinities and Activities

    West, Graham M.; Pascal, Bruce D.; Ng, Ley-Moy; Soon, Fen-Fen; Melcher, Karsten; Xu, H. Eric; Chalmers, Michael J.; Griffin, Patrick R.

    2013-01-01

    Plants regulate growth and respond to environmental stress through abscisic acid (ABA) regulated pathways, and as such these pathways are of primary interest for biological and agricultural research. The ABA response is first perceived by the PYR/PYL/RCAR class of START protein receptors. These ABA activated receptors disrupt phosphatase inhibition of Snf1-related kinases (SnRKs) enabling kinase signaling. Here, insights into the structural mechanism of proteins in the ABA signaling pathway (...

  6. Ectopic cross-talk between thyroid and retinoic acid signaling: A possible etiology for spinal neural tube defects.

    Li, Huili; Bai, Baoling; Zhang, Qin; Bao, Yihua; Guo, Jin; Chen, Shuyuan; Miao, Chunyue; Liu, Xiaozhen; Zhang, Ting

    2015-12-01

    Previous studies have highlighted the connections between neural tube defects (NTDs) and both thyroid hormones (TH) and vitamin A. However, whether the two hormonal signaling pathways interact in NTDs has remained unclear. We measured the expression levels of TH signaling genes in human fetuses with spinal NTDs associated with maternal hyperthyroidism as well as levels of retinoic acid (RA) signaling genes in mouse fetuses exposed to an overdose of RA using NanoString or real-time PCR on spinal cord tissues. Interactions between the two signaling pathways were detected by ChIP assays. The data revealed attenuated DIO2/DIO3 switching in fetuses with NTDs born to hyperthyroid mothers. The promoters of the RA signaling genes CRABP1 and RARB were ectopically occupied by increased RXRG and RXRB but displayed decreased levels of inhibitory histone modifications, suggesting that elevated TH signaling abnormally stimulates RA signaling genes. Conversely, in the mouse model, the observed decrease in Dio3 expression could be explained by increased levels of inhibitory histone modifications in the Dio3 promoter region, suggesting that overactive RA signaling may ectopically derepress TH signaling. This study thus raises in vivo a possible abnormal cross-promotion between two different hormonal signals through their common RXRs and the subsequent recruitment of histone modifications, prompting further investigation into their involvement in the etiology of spinal NTDs. Copyright © 2015 Elsevier B.V. All rights reserved.

  7. Retinoic Acid signalling and the control of meiotic entry in the human fetal gonad.

    Andrew J Childs

    Full Text Available The development of mammalian fetal germ cells along oogenic or spermatogenic fate trajectories is dictated by signals from the surrounding gonadal environment. Germ cells in the fetal testis enter mitotic arrest, whilst those in the fetal ovary undergo sex-specific entry into meiosis, the initiation of which is thought to be mediated by selective exposure of fetal ovarian germ cells to mesonephros-derived retinoic acid (RA. Aspects of this model are hard to reconcile with the spatiotemporal pattern of germ cell differentiation in the human fetal ovary, however. We have therefore examined the expression of components of the RA synthesis, metabolism and signalling pathways, and their downstream effectors and inhibitors in germ cells around the time of the initiation of meiosis in the human fetal gonad. Expression of the three RA-synthesising enzymes, ALDH1A1, 2 and 3 in the fetal ovary and testis was equal to or greater than that in the mesonephros at 8-9 weeks gestation, indicating an intrinsic capacity within the gonad to synthesise RA. Using immunohistochemistry to detect RA receptors RARα, β and RXRα, we find germ cells to be the predominant target of RA signalling in the fetal human ovary, but also reveal widespread receptor nuclear localization indicative of signalling in the testis, suggesting that human fetal testicular germ cells are not efficiently shielded from RA by the action of the RA-metabolising enzyme CYP26B1. Consistent with this, expression of CYP26B1 was greater in the human fetal ovary than testis, although the sexually-dimorphic expression patterns of the germ cell-intrinsic regulators of meiotic initiation, STRA8 and NANOS2, appear conserved. Finally, we demonstrate that RA induces a two-fold increase in STRA8 expression in cultures of human fetal testis, but is not sufficient to cause widespread meiosis-associated gene expression. Together, these data indicate that while local production of RA within the fetal ovary may

  8. Retinoic Acid Signalling and the Control of Meiotic Entry in the Human Fetal Gonad

    Kinnell, Hazel L.; Anderson, Richard A.; Saunders, Philippa T. K.

    2011-01-01

    The development of mammalian fetal germ cells along oogenic or spermatogenic fate trajectories is dictated by signals from the surrounding gonadal environment. Germ cells in the fetal testis enter mitotic arrest, whilst those in the fetal ovary undergo sex-specific entry into meiosis, the initiation of which is thought to be mediated by selective exposure of fetal ovarian germ cells to mesonephros-derived retinoic acid (RA). Aspects of this model are hard to reconcile with the spatiotemporal pattern of germ cell differentiation in the human fetal ovary, however. We have therefore examined the expression of components of the RA synthesis, metabolism and signalling pathways, and their downstream effectors and inhibitors in germ cells around the time of the initiation of meiosis in the human fetal gonad. Expression of the three RA-synthesising enzymes, ALDH1A1, 2 and 3 in the fetal ovary and testis was equal to or greater than that in the mesonephros at 8–9 weeks gestation, indicating an intrinsic capacity within the gonad to synthesise RA. Using immunohistochemistry to detect RA receptors RARα, β and RXRα, we find germ cells to be the predominant target of RA signalling in the fetal human ovary, but also reveal widespread receptor nuclear localization indicative of signalling in the testis, suggesting that human fetal testicular germ cells are not efficiently shielded from RA by the action of the RA-metabolising enzyme CYP26B1. Consistent with this, expression of CYP26B1 was greater in the human fetal ovary than testis, although the sexually-dimorphic expression patterns of the germ cell-intrinsic regulators of meiotic initiation, STRA8 and NANOS2, appear conserved. Finally, we demonstrate that RA induces a two-fold increase in STRA8 expression in cultures of human fetal testis, but is not sufficient to cause widespread meiosis-associated gene expression. Together, these data indicate that while local production of RA within the fetal ovary may be important in

  9. Jasmonate mediates salt-induced nicotine biosynthesis in tobacco (Nicotiana tabacum L.

    Xiaodong Chen

    2016-04-01

    Full Text Available Jasmonate (JA, as an important signal, plays a key role in multiple processes of plant growth, development and stress response. Nicotine and related pyridine alkaloids in tobacco (Nicotiana tabacum L. are essential secondary metabolites. Whether environmental factors control nicotine biosynthesis and the underlying mechanism remains previously unreported. Here, we applied physiological and biochemical approaches to investigate how salt stress affects nicotine biosynthesis in tobacco. We found that salt stress induced the biosynthesis of JA, which subsequently triggered the activation of JA-responsive gene expression and, ultimately, nicotine synthesis. Bioinformatics analysis revealed the existence of many NtMYC2a-recognized G-box motifs in the promoter regions of NtLOX, NtAOS, NtAOC and NtOPR genes. Applying exogenous JA increased nicotine content, while suppressing JA biosynthesis reduced nicotine biosynthesis. Salt treatment could not efficiently induce nicotine biosynthesis in transgenic anti-COI1 tobacco plants. These results demonstrate that JA acts as the essential signal which triggers nicotine biosynthesis in tobacco after salt stress.

  10. Control of Carbon Assimilation and Partitioning by Jasmonate: An Accounting of Growth–Defense Tradeoffs

    Nathan E. Havko

    2016-01-01

    Full Text Available Plant growth is often constrained by the limited availability of resources in the microenvironment. Despite the continuous threat of attack from insect herbivores and pathogens, investment in defense represents a lost opportunity to expand photosynthetic capacity in leaves and absorption of nutrients and water by roots. To mitigate the metabolic expenditure on defense, plants have evolved inducible defense strategies. The plant hormone jasmonate (JA is a key regulator of many inducible defenses. Synthesis of JA in response to perceived danger leads to the deployment of a variety of defensive structures and compounds, along with a potent inhibition of growth. Genetic studies have established an important role for JA in mediating tradeoffs between growth and defense. However, several gaps remain in understanding of how JA signaling inhibits growth, either through direct transcriptional control of JA-response genes or crosstalk with other signaling pathways. Here, we highlight recent progress in uncovering the role of JA in controlling growth-defense balance and its relationship to resource acquisition and allocation. We also discuss tradeoffs in the context of the ability of JA to promote increased leaf mass per area (LMA, which is a key indicator of leaf construction costs and leaf life span.

  11. Complex Interplay of Hormonal Signals during Grape Berry Ripening

    Ana Margarida Fortes

    2015-05-01

    Full Text Available Grape and wine production and quality is extremely dependent on the fruit ripening process. Sensory and nutritional characteristics are important aspects for consumers and their development during fruit ripening involves complex hormonal control. In this review, we explored data already published on grape ripening and compared it with the hormonal regulation of ripening of other climacteric and non-climacteric fruits. The roles of abscisic acid, ethylene, and brassinosteroids as promoters of ripening are discussed, as well as the role of auxins, cytokinins, gibberellins, jasmonates, and polyamines as inhibitors of ripening. In particular, the recently described role of polyamine catabolism in grape ripening is discussed, together with its putative interaction with other hormones. Furthermore, other recent examples of cross-talk among the different hormones are presented, revealing a complex interplay of signals during grape development and ripening.

  12. Effect of methyl jasmonate on secondary metabolites of sweet basil (Ocimum basilicum L.).

    Kim, Hyun-Jin; Chen, Feng; Wang, Xi; Rajapakse, Nihal C

    2006-03-22

    The effect of methyl jasmonate (MeJA) in terms of its induction of inherent bioactive chemicals in sweet basil (Ocimum basilicum L.) was evaluated after MeJA was sprayed on healthy basil plants. The total phenolic content of the sweet basil significantly increased after 0.1 and 0.5 mM MeJA treatments compared with the control not subjected to MeJA. Two phenolic compounds, rosmarinic acid (RA) and caffeic acid (CA), were identified as strong antioxidant constituents of the sweet basil. Their amounts also significantly increased after the MeJA treatment. In addition, eugenol and linalool increased 56 and 43%, respectively, by the 0.5 mM MeJA treatment. Due to the accumulation of RA, CA, and eugenol, which possess strong 2,2-diphenyl-1-picrylhydrazyl (DPPH*) free radical scavenging activities, the antioxidant activity of the sweet basil extract was 2.3-fold greater than that of the control after the 0.5 mM MeJA treatment. In the DPPH* assay, the EC50 values of RA, CA, and eugenol were determined as 23, 46, and 59 microM, respectively, which indicated they were 6-, 3-, and 2.4-fold more efficient than BHT (140 microM). Besides, an unidentified HPLC peak in the methanolic extract of the sweet basil was 4.3-fold higher than that of the control after the 0.5 mM MeJA treatment.

  13. Increased antioxidant activity and polyphenol metabolites in methyl jasmonate treated mung bean (Vigna radiata sprouts

    Li LI

    Full Text Available Abstract Mung bean sprouts are a popular health food both in China and worldwide. We determined the optimal concentration of exogenous methyl jasmonate (MeJA for the promotion of the sprouting in mung beans (Vigna radiata. The 1,1-diphenyl-2- picrylhydrazyl radical (DPPH scavenging test showed that MeJA application resulted in significantly improved antioxidant capacity in the sprouts 72 h later. Measurement of total polyphenols in MeJA-treated beans from 0 to 168 h, using Folin–Ciocalteu colorimetry, showed that the polyphenols changing was significantly correlated with antioxidant activity. The main polyphenols isovitexin, kaempferol-3-O-rutinoside, daidzein, genistein, isoquercitrin, p-coumaric acid, and caffeic acid were quantified using high-performance liquid chromatography (HPLC/QqQ MS and partial least squares discriminant analysis (PLS-DA. MeJA promoted the production of polyphenols, metabolites, and antioxidants in the sprouts; therefore, its use may allow sprouts to be prepared more quickly or increase their nutritional value.

  14. Determination of Tobramycin in M9 Medium by LC-MS/MS: Signal Enhancement by Trichloroacetic Acid

    Huang, Liusheng; Haagensen, Janus Anders Juul; Verotta, Davide

    2018-01-01

    mM ammonium formate and 0.14% trifluoroacetic acid and acetonitrile containing 0.1% trifluoroacetic acid in a gradient mode. ESI+ and MRM with ion m/z 468 → 324 for tobramycin and m/z 473 -> 327 for the IS were used for quantification. The calibration curve concentration range was 50-25000 ng....../mL. Matrix effect from M9 media was not significant when compared with injection solvents, but signal enhancement by trichloroacetic acid was significant (∼ 3 fold). The method is simple, fast, and reliable. Using the method, the in vitro PK/PD model was tested with one bolus dose of tobramycin....

  15. Postnatal changes in somatic gamma-aminobutyric acid signalling in the rat hippocampus.

    Tyzio, Roman; Minlebaev, Marat; Rheims, Sylvain; Ivanov, Anton; Jorquera, Isabelle; Holmes, Gregory L; Zilberter, Yuri; Ben-Ari, Yehezkiel; Khazipov, Rustem

    2008-05-01

    During postnatal development of the rat hippocampus, gamma-aminobutyric acid (GABA) switches its action on CA3 pyramidal cells from excitatory to inhibitory. To characterize the underlying changes in the GABA reversal potential, we used somatic cell-attached recordings of GABA(A) and N-methyl-D-aspartate channels to monitor the GABA driving force and resting membrane potential, respectively. We found that the GABA driving force is strongly depolarizing during the first postnatal week. The strength of this depolarization rapidly declines with age, although GABA remains slightly depolarizing, by a few millivolts, even in adult neurons. Reduction in the depolarizing GABA driving force was due to a progressive negative shift of the reversal potential of GABA currents. Similar postnatal changes in GABA signalling were also observed using the superfused hippocampus preparation in vivo, and in the hippocampal interneurons in vitro. We also found that in adult pyramidal cells, somatic GABA reversal potential is maintained at a slightly depolarizing level by bicarbonate conductance, chloride-extrusion and chloride-loading systems. Thus, the postnatal excitatory-to-inhibitory switch in somatic GABA signalling is associated with a negative shift of the GABA reversal potential but without a hyperpolarizing switch in the polarity of GABA responses. These results also suggest that in adult CA3 pyramidal cells, somatic GABAergic inhibition takes place essentially through shunting rather than hyperpolarization. Apparent hyperpolarizing GABA responses previously reported in the soma of CA3 pyramidal cells are probably due to cell depolarization during intracellular or whole-cell recordings.

  16. Multiple signal transduction pathways in okadaic acid induced apoptosis in HeLa cells

    Jayaraj, R.; Gupta, Nimesh; Rao, P.V. Lakshmana

    2009-01-01

    Okadaic acid (OA) is the major component of diarrhetic shell fish poisoning toxins and a potent inhibitor of protein phosphatase 1 and 2A. We investigated the signal transduction pathways involved in OA induced cell death in HeLa cells. OA induced cytotoxicity and apoptosis at IC50 of 100 nM. OA treatment resulted in time dependent increase in reactive oxygen species and depleted intracellular glutathione levels. Loss of mitochondrial membrane permeability led to translocation of bax, cytochrome-c and AIF from mitochondria to cytosol. The cells under fluorescence microscope showed typical apoptotic morphology with condensed chromatin, and nuclear fragmentation. We investigated the mitochondrial-mediated caspase cascade. The time dependent activation and cleavage of of bax, caspases-8, 10, 9, 3 and 7 was observed in Western blot analysis. In addition to caspase-dependent pathway AIF mediated caspase-independent pathway was involved in OA mediated cell death. OA also caused time dependent inhibition of protein phosphatase 2A activity and phosphorylation of p38 and p42/44 MAP kinases. Inhibitor studies with Ac-DEVO-CHO and Z-VAD-FMK could not prevent the phosphorylation of p38 and p42/44 MAP kinases. Our experiments with caspase inhibitors Ac-DEVD-CHO, Z-IETD-FMK and Z-VAD-FMK inhibited capsase-3, 8 cleavages but did not prevent OA-induced apoptosis and DNA fragmentation. Similarly, pretreatment with cyclosporin-A and N-acetylcysteine could not prevent the DNA fragmentation. In summary, the results of our study show that OA induces multiple signal transduction pathways acting either independently or simultaneously leading to apoptosis

  17. Bile acids modulate signaling by functional perturbation of plasma membrane domains.

    Zhou, Yong; Maxwell, Kelsey N; Sezgin, Erdinc; Lu, Maryia; Liang, Hong; Hancock, John F; Dial, Elizabeth J; Lichtenberger, Lenard M; Levental, Ilya

    2013-12-13

    Eukaryotic cell membranes are organized into functional lipid and protein domains, the most widely studied being membrane rafts. Although rafts have been associated with numerous plasma membrane functions, the mechanisms by which these domains themselves are regulated remain undefined. Bile acids (BAs), whose primary function is the solubilization of dietary lipids for digestion and absorption, can affect cells by interacting directly with membranes. To investigate whether these interactions affected domain organization in biological membranes, we assayed the effects of BAs on biomimetic synthetic liposomes, isolated plasma membranes, and live cells. At cytotoxic concentrations, BAs dissolved synthetic and cell-derived membranes and disrupted live cell plasma membranes, implicating plasma membrane damage as the mechanism for BA cellular toxicity. At subtoxic concentrations, BAs dramatically stabilized domain separation in Giant Plasma Membrane Vesicles without affecting protein partitioning between coexisting domains. Domain stabilization was the result of BA binding to and disordering the nonraft domain, thus promoting separation by enhancing domain immiscibility. Consistent with the physical changes observed in synthetic and isolated biological membranes, BAs reorganized intact cell membranes, as evaluated by the spatial distribution of membrane-anchored Ras isoforms. Nanoclustering of K-Ras, related to nonraft membrane domains, was enhanced in intact plasma membranes, whereas the organization of H-Ras was unaffected. BA-induced changes in Ras lateral segregation potentiated EGF-induced signaling through MAPK, confirming the ability of BAs to influence cell signal transduction by altering the physical properties of the plasma membrane. These observations suggest general, membrane-mediated mechanisms by which biological amphiphiles can produce their cellular effects.

  18. Sialic Acid on the Glycosylphosphatidylinositol Anchor Regulates PrP-mediated Cell Signaling and Prion Formation.

    Bate, Clive; Nolan, William; Williams, Alun

    2016-01-01

    The prion diseases occur following the conversion of the cellular prion protein (PrP(C)) into disease-related isoforms (PrP(Sc)). In this study, the role of the glycosylphosphatidylinositol (GPI) anchor attached to PrP(C) in prion formation was examined using a cell painting technique. PrP(Sc) formation in two prion-infected neuronal cell lines (ScGT1 and ScN2a cells) and in scrapie-infected primary cortical neurons was increased following the introduction of PrP(C). In contrast, PrP(C) containing a GPI anchor from which the sialic acid had been removed (desialylated PrP(C)) was not converted to PrP(Sc). Furthermore, the presence of desialylated PrP(C) inhibited the production of PrP(Sc) within prion-infected cortical neurons and ScGT1 and ScN2a cells. The membrane rafts surrounding desialylated PrP(C) contained greater amounts of sialylated gangliosides and cholesterol than membrane rafts surrounding PrP(C). Desialylated PrP(C) was less sensitive to cholesterol depletion than PrP(C) and was not released from cells by treatment with glimepiride. The presence of desialylated PrP(C) in neurons caused the dissociation of cytoplasmic phospholipase A2 from PrP-containing membrane rafts and reduced the activation of cytoplasmic phospholipase A2. These findings show that the sialic acid moiety of the GPI attached to PrP(C) modifies local membrane microenvironments that are important in PrP-mediated cell signaling and PrP(Sc) formation. These results suggest that pharmacological modification of GPI glycosylation might constitute a novel therapeutic approach to prion diseases. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  19. Gallic acid inhibits vascular calcification through the blockade of BMP2-Smad1/5/8 signaling pathway.

    Kee, Hae Jin; Cho, Soo-Na; Kim, Gwi Ran; Choi, Sin Young; Ryu, Yuhee; Kim, In Kyeom; Hong, Young Joon; Park, Hyung Wook; Ahn, Youngkeun; Cho, Jeong Gwan; Park, Jong Chun; Jeong, Myung Ho

    2014-11-01

    Vascular calcification is associated with increased risk of morbidity and mortality in patients with cardiovascular diseases, chronic kidney diseases, and diabetes. Gallic acid, a natural compound found in gallnut and green tea, is known to be antifungal, antioxidant, and anticancer. Here we investigated the effect of gallic acid on vascular smooth muscle cell (VSMC) calcification and the underlying mechanism. Gallic acid inhibited inorganic phosphate-induced osteoblast differentiation markers as well as calcification phenotypes (as determined by calcium deposition, Alizarin Red, and Von Kossa staining). Knockdown of BMP2 or Noggin blocked phosphate-induced calcification. Gallic acid suppressed phosphorylation of Smad1/5/8 protein induced by inorganic phosphate. Taken together, we suggest that gallic acid acts as a novel therapeutic agent of vascular calcification by mediating BMP2-Smad1/5/8 signaling pathway. Copyright © 2014 Elsevier Inc. All rights reserved.

  20. Conjugated linoleic acid induces human adipocyte delipidation: autocrine/paracrine regulation of MEK/ERK signaling by adipocytokines

    Brown, J Mark; Boysen, Maria Sandberg; Chung, Soonkyu

    2004-01-01

    of MEK/ERK could be attenuated by pretreatment with U0126 and pertussis toxin. In parallel, pretreatment with U0126 blocked the ability of trans-10, cis-12 CLA to alter gene expression and attenuate glucose and fatty acid uptake of the cultures. Intriguingly, the induction by CLA of MEK/ERK signaling...

  1. Bile Acid-Mediated Sphingosine-1-Phosphate Receptor 2 Signaling Promotes Neuroinflammation during Hepatic Encephalopathy in Mice

    Matthew McMillin

    2017-07-01

    Full Text Available Hepatic encephalopathy (HE is a neuropsychiatric complication that occurs due to deteriorating hepatic function and this syndrome influences patient quality of life, clinical management strategies and survival. During acute liver failure, circulating bile acids increase due to a disruption of the enterohepatic circulation. We previously identified that bile acid-mediated signaling occurs in the brain during HE and contributes to cognitive impairment. However, the influences of bile acids and their downstream signaling pathways on HE-induced neuroinflammation have not been assessed. Conjugated bile acids, such as taurocholic acid (TCA, can activate sphingosine-1-phosphate receptor 2 (S1PR2, which has been shown to promote immune cell infiltration and inflammation in other models. The current study aimed to assess the role of bile-acid mediated S1PR2 signaling in neuroinflammation and disease progression during azoxymethane (AOM-induced HE in mice. Our findings demonstrate a temporal increase of bile acids in the cortex during AOM-induced HE and identified that cortical bile acids were elevated as an early event in this model. In order to classify the specific bile acids that were elevated during HE, a metabolic screen was performed and this assay identified that TCA was increased in the serum and cortex during AOM-induced HE. To reduce bile acid concentrations in the brain, mice were fed a diet supplemented with cholestyramine, which alleviated neuroinflammation by reducing proinflammatory cytokine expression in the cortex compared to the control diet-fed AOM-treated mice. S1PR2 was expressed primarily in neurons and TCA treatment increased chemokine ligand 2 mRNA expression in these cells. The infusion of JTE-013, a S1PR2 antagonist, into the lateral ventricle prior to AOM injection protected against neurological decline and reduced neuroinflammation compared to DMSO-infused AOM-treated mice. Together, this identifies that reducing bile acid

  2. Identification and Analysis of Jasmonate Pathway Genes in Coffea canephora (Robusta Coffee) by In Silico Approach.

    Bharathi, Kosaraju; Sreenath, H L

    2017-07-01

    Coffea canephora is the commonly cultivated coffee species in the world along with Coffea arabica . Different pests and pathogens affect the production and quality of the coffee. Jasmonic acid (JA) is a plant hormone which plays an important role in plants growth, development, and defense mechanisms, particularly against insect pests. The key enzymes involved in the production of JA are lipoxygenase, allene oxide synthase, allene oxide cyclase, and 12-oxo-phytodienoic reductase. There is no report on the genes involved in JA pathway in coffee plants. We made an attempt to identify and analyze the genes coding for these enzymes in C. canephora . First, protein sequences of jasmonate pathway genes from model plant Arabidopsis thaliana were identified in the National Center for Biotechnology Information (NCBI) database. These protein sequences were used to search the web-based database Coffee Genome Hub to identify homologous protein sequences in C. canephora genome using Basic Local Alignment Search Tool (BLAST). Homologous protein sequences for key genes were identified in the C. canephora genome database. Protein sequences of the top matches were in turn used to search in NCBI database using BLAST tool to confirm the identity of the selected proteins and to identify closely related genes in species. The protein sequences from C. canephora database and the top matches in NCBI were aligned, and phylogenetic trees were constructed using MEGA6 software and identified the genetic distance of the respective genes. The study identified the four key genes of JA pathway in C. canephora , confirming the conserved nature of the pathway in coffee. The study expected to be useful to further explore the defense mechanisms of coffee plants. JA is a plant hormone that plays an important role in plant defense against insect pests. Genes coding for the 4 key enzymes involved in the production of JA viz., LOX, AOS, AOC, and OPR are identified in C. canephora (robusta coffee) by

  3. Impaired nutrient signaling and body weight control in a Na+ neutral amino acid cotransporter (Slc6a19)-deficient mouse.

    Bröer, Angelika; Juelich, Torsten; Vanslambrouck, Jessica M; Tietze, Nadine; Solomon, Peter S; Holst, Jeff; Bailey, Charles G; Rasko, John E J; Bröer, Stefan

    2011-07-29

    Amino acid uptake in the intestine and kidney is mediated by a variety of amino acid transporters. To understand the role of epithelial neutral amino acid uptake in whole body homeostasis, we analyzed mice lacking the apical broad-spectrum neutral (0) amino acid transporter B(0)AT1 (Slc6a19). A general neutral aminoaciduria was observed similar to human Hartnup disorder which is caused by mutations in SLC6A19. Na(+)-dependent uptake of neutral amino acids into the intestine and renal brush-border membrane vesicles was abolished. No compensatory increase of peptide transport or other neutral amino acid transporters was detected. Mice lacking B(0)AT1 showed a reduced body weight. When adapted to a standard 20% protein diet, B(0)AT1-deficient mice lost body weight rapidly on diets containing 6 or 40% protein. Secretion of insulin in response to food ingestion after fasting was blunted. In the intestine, amino acid signaling to the mammalian target of rapamycin (mTOR) pathway was reduced, whereas the GCN2/ATF4 stress response pathway was activated, indicating amino acid deprivation in epithelial cells. The results demonstrate that epithelial amino acid uptake is essential for optimal growth and body weight regulation.

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

    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.

  5. Tributyltin and triphenyltin inhibit osteoclast differentiation through a retinoic acid receptor-dependent signaling pathway

    Yonezawa, Takayuki; Hasegawa, Shin-ichi; Ahn, Jae-Yong; Cha, Byung-Yoon; Teruya, Toshiaki; Hagiwara, Hiromi; Nagai, Kazuo; Woo, Je-Tae

    2007-01-01

    Organotin compounds, such as tributyltin (TBT) and triphenyltin (TPT), have been widely used in agriculture and industry. Although these compounds are known to have many toxic effects, including endocrine-disrupting effects, their effects on bone resorption are unknown. In this study, we investigated the effects of organotin compounds, such as monobutyltin (MBT), dibutyltin (DBT), TBT, and TPT, on osteoclast differentiation using mouse monocytic RAW264.7 cells. MBT and DBT had no effects, whereas TBT and TPT dose-dependently inhibited osteoclast differentiation at concentrations of 3-30 nM. Treatment with a retinoic acid receptor (RAR)-specific antagonist, Ro41-5253, restored the inhibition of osteoclastogenesis by TBT and TPT. TBT and TPT reduced receptor activator of nuclear factor-κB ligand (RANKL) induced nuclear factor of activated T cells (NFAT) c1 expression, and the reduction in NFATc1 expression was recovered by Ro41-5253. Our results suggest that TBT and TPT suppress osteoclastogenesis by inhibiting RANKL-induced NFATc1 expression via an RAR-dependent signaling pathway

  6. Cell Identity Switching Regulated by Retinoic Acid Signaling Maintains Homogeneous Segments in the Hindbrain.

    Addison, Megan; Xu, Qiling; Cayuso, Jordi; Wilkinson, David G

    2018-06-04

    The patterning of tissues to form subdivisions with distinct and homogeneous regional identity is potentially disrupted by cell intermingling. Transplantation studies suggest that homogeneous segmental identity in the hindbrain is maintained by identity switching of cells that intermingle into another segment. We show that switching occurs during normal development and is mediated by feedback between segment identity and the retinoic acid degrading enzymes, cyp26b1 and cyp26c1. egr2, which specifies the segmental identity of rhombomeres r3 and r5, underlies the lower expression level of cyp26b1 and cyp26c1 in r3 and r5 compared with r2, r4, and r6. Consequently, r3 or r5 cells that intermingle into adjacent segments encounter cells with higher cyp26b1/c1 expression, which we find is required for downregulation of egr2b expression. Furthermore, egr2b expression is regulated in r2, r4, and r6 by non-autonomous mechanisms that depend upon the number of neighbors that express egr2b. These findings reveal that a community regulation of retinoid signaling maintains homogeneous segmental identity. Copyright © 2018 The Author(s). Published by Elsevier Inc. All rights reserved.

  7. Autophagic dedifferentiation induced by cooperation between TOR inhibitor and retinoic acid signals in budding tunicates.

    Kawamura, Kaz; Yoshida, Takuto; Sekida, Satoko

    2018-01-15

    Asexual bud development in the budding tunicate Polyandrocarpa misakiensis involves transdifferentiation of multipotent epithelial cells, which is triggered by retinoic acid (RA), and thrives under starvation after bud isolation from the parent. This study aimed to determine cell and molecular mechanisms of dedifferentiation that occur during the early stage of transdifferentiation. During dedifferentiation, the numbers of autophagosomes, lysosomes, and secondary lysosomes increased remarkably. Mitochondrial degradation and exosome discharge also occurred in the atrial epithelium. Autophagy-related gene 7 (Atg7) and lysosomal proton pump A gene (PumpA) were activated during the dedifferentiation stage. When target of rapamycin (TOR) inhibitor was administered to growing buds without isolating them from the parent, phagosomes and secondary lysosomes became prominent. TOR inhibitor induced Atg7 only in the presence of RA. In contrast, when growing buds were treated with RA, lysosomes, secondary lysosomes, and mitochondrial degradation were prematurely induced. RA significantly activated PumpA in a retinoid X receptor-dependent manner. Our results indicate that in P. misakiensis, TOR inhibition and RA signals act in synergy to accomplish cytoplasmic clearance for dedifferentiation. Copyright © 2017 Elsevier Inc. All rights reserved.

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

    Melcher, Karsten; Ng, Ley-Moy; Zhou, X. Edward; Soon, Fen-Fen; Xu, Yong; Suino-Powell, Kelly M.; Park, Sang-Youl; Weiner, Joshua J.; Fujii, Hiroaki; Chinnusamy, Viswanathan; Kovach, Amanda; Li, Jun; Wang, Yonghong; Li, Jiayang; Peterson, Francis C.; Jensen, Davin R.; Yong, Eu-Leong; Volkman, Brian F.; Cutler, Sean R.; Zhu, Jian-Kang; Xu, H. Eric

    2009-01-01

    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.

  9. Jasmonate-responsive transcription factors regulating plant secondary metabolism.

    Zhou, Meiliang; Memelink, Johan

    2016-01-01

    Plants produce a large variety of secondary metabolites including alkaloids, glucosinolates, terpenoids and phenylpropanoids. These compounds play key roles in plant-environment interactions and many of them have pharmacological activity in humans. Jasmonates (JAs) are plant hormones which induce biosynthesis of many secondary metabolites. JAs-responsive transcription factors (TFs) that regulate the JAs-induced accumulation of secondary metabolites belong to different families including AP2/ERF, bHLH, MYB and WRKY. Here, we give an overview of the types and functions of TFs that have been identified in JAs-induced secondary metabolite biosynthesis, and highlight their similarities and differences in regulating various biosynthetic pathways. We review major recent developments regarding JAs-responsive TFs mediating secondary metabolite biosynthesis, and provide suggestions for further studies. Copyright © 2016 Elsevier Inc. All rights reserved.

  10. A hepatic amino acid/mTOR/S6K-dependent signalling pathway modulates systemic lipid metabolism via neuronal signals.

    Uno, Kenji; Yamada, Tetsuya; Ishigaki, Yasushi; Imai, Junta; Hasegawa, Yutaka; Sawada, Shojiro; Kaneko, Keizo; Ono, Hiraku; Asano, Tomoichiro; Oka, Yoshitomo; Katagiri, Hideki

    2015-08-13

    Metabolism is coordinated among tissues and organs via neuronal signals. Levels of circulating amino acids (AAs), which are elevated in obesity, activate the intracellular target of rapamycin complex-1 (mTORC1)/S6kinase (S6K) pathway in the liver. Here we demonstrate that hepatic AA/mTORC1/S6K signalling modulates systemic lipid metabolism via a mechanism involving neuronal inter-tissue communication. Hepatic expression of an AA transporter, SNAT2, activates the mTORC1/S6K pathway, and markedly elevates serum triglycerides (TGs), while downregulating adipose lipoprotein lipase (LPL). Hepatic Rheb or active-S6K expression have similar metabolic effects, whereas hepatic expression of dominant-negative-S6K inhibits TG elevation in SNAT2 mice. Denervation, pharmacological deafferentation and β-blocker administration suppress obesity-related hypertriglyceridemia with adipose LPL upregulation, suggesting that signals are transduced between liver and adipose tissue via a neuronal pathway consisting of afferent vagal and efferent sympathetic nerves. Thus, the neuronal mechanism uncovered here serves to coordinate amino acid and lipid levels and contributes to the development of obesity-related hypertriglyceridemia.

  11. Activity of cell wall degrading glycanases in methyl jasmonate-induced leaf abscission in Kalanchoe blossfeldiana

    Marian Saniewski; Ewa Gajewska; Henryk Urbanek

    2013-01-01

    It was found previously that methyl jasmonate (JA-Me) induced leaf abscission in Kalanchoe blossfeldiana. In present studies it was shown that JA-Me markedly increased the total activities of cellulase, polygalacturonase, pectinase and xylanase in petioles, but did not affect activities of these enzymes in the blades and apical part of shoots of K. blossfeldiana. These results suggest that methyl jasmonate promotes the degradation of cell wall polysaccharides in the abscission zone and in thi...

  12. Lipoic acid attenuates inflammation via cAMP and protein kinase A signaling.

    Sonemany Salinthone

    2010-09-01

    Full Text Available Abnormal regulation of the inflammatory response is an important component of diseases such as diabetes, Alzheimer's disease and multiple sclerosis (MS. Lipoic acid (LA has been shown to have antioxidant and anti-inflammatory properties and is being pursued as a therapy for these diseases. We first reported that LA stimulates cAMP production via activation of G-protein coupled receptors and adenylyl cyclases. LA also suppressed NK cell activation and cytotoxicity. In this study we present evidence supporting the hypothesis that the anti-inflammatory properties of LA are mediated by the cAMP/PKA signaling cascade. Additionally, we show that LA oral administration elevates cAMP levels in MS subjects.We determined the effects of LA on IL-6, IL-17 and IL-10 secretion using ELISAs. Treatment with 50 µg/ml and 100 µg/ml LA significantly reduced IL-6 levels by 19 and 34%, respectively, in T cell enriched PBMCs. IL-17 levels were also reduced by 35 and 50%, respectively. Though not significant, LA appeared to have a biphasic effect on IL-10 production. Thymidine incorporation studies showed LA inhibited T cell proliferation by 90%. T-cell activation was reduced by 50% as measured by IL-2 secretion. Western blot analysis showed that LA treatment increased phosphorylation of Lck, a downstream effector of protein kinase A. Pretreatment with a peptide inhibitor of PKA, PKI, blocked LA inhibition of IL-2 and IFN gamma production, indicating that PKA mediates these responses. Oral administration of 1200 mg LA to MS subjects resulted in increased cAMP levels in PBMCs four hours after ingestion. Average cAMP levels in 20 subjects were 43% higher than baseline.Oral administration of LA in vivo resulted in significant increases in cAMP concentration. The anti-inflammatory effects of LA are mediated in part by the cAMP/PKA signaling cascade. These novel findings enhance our understanding of the mechanisms of action of LA.