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Sample records for acid regulates root

  1. [Regulation effects of grafting on cinnamic acid and vanillin in eggplant root exudates].

    Science.gov (United States)

    Chen, Shao-li; Zhou, Bao-li; Wang, Ru-hua; Fu, Ya-wen

    2008-11-01

    Cinnamic acid and vanillin are the allelochemicals commonly existed in eggplant root exudates. With pot culture experiment, the regulation effects of grafting on the cinnamic acid and vanillin in eggplant root exudates were studied, and the results showed that grafting decreased the amount of the two substances, especially of vanillin, in eggplants root system. The maximum reduction amount of cinnamic acid reached 68.96%, and that of vanillin reached 100%. Under the stress of exotic cinnamic acid and vanillin, especially of exotic cinnamic acid, grafting relieved the autotoxicity of the two substances on eggplants. Compared with own-rooted eggplant, grafted eggplant had a higher plant height and a larger stem diameter, its leaf chlorophyll content increased by 5.26%-13.12%, root electric conductivity and MDA content decreased, and root SOD activity enhanced.

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

    Institute of Scientific and Technical Information of China (English)

    王建荣; 王蕾; 胡婷; 李文超; 薛绍武

    2014-01-01

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

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

    Science.gov (United States)

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

    2009-01-23

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

  4. Sulfur nutrient availability regulates root elongation by affecting root indole-3-acetic acid levels and the stem cell niche

    Institute of Scientific and Technical Information of China (English)

    Qing Zhao; Yu Wu; Lei Gao; Jun Ma; Chuan-You Li; Cheng-Bin Xiang

    2014-01-01

    Sulfur is an essential macronutrient for plants with numerous biological functions. However, the influence of sulfur nutrient availability on the regulation of root development remains largely unknown. Here, we report the response of Arabidopsis thaliana L. root development and growth to different levels of sulfate, demonstrating that low sulfate levels promote the primary root elongation. By using various reporter lines, we examined in vivo IAA level and distribution, cel division, and root meristem in response to different sulfate levels. Meanwhile the dynamic changes of in vivo cysteine, glutathione, and IAA levels were measured. Root cysteine, glutathione, and IAA levels are positively correlated with external sulfate levels in the physiological range, which eventual y affect root system architecture. Low sulfate levels also downregulate the genes involved in auxin biosynthesis and transport, and elevate the accumulation of PLT1 and PLT2. This study suggests that sulfate level affects the primary root elongation by regulating the endogenous auxin level and root stem cel niche maintenance.

  5. Sulfur nutrient availability regulates root elongation by affecting root indole-3-acetic acid levels and the stem cell niche.

    Science.gov (United States)

    Zhao, Qing; Wu, Yu; Gao, Lei; Ma, Jun; Li, Chuan-You; Xiang, Cheng-Bin

    2014-12-01

    Sulfur is an essential macronutrient for plants with numerous biological functions. However, the influence of sulfur nutrient availability on the regulation of root development remains largely unknown. Here, we report the response of Arabidopsis thaliana L. root development and growth to different levels of sulfate, demonstrating that low sulfate levels promote the primary root elongation. By using various reporter lines, we examined in vivo IAA level and distribution, cell division, and root meristem in response to different sulfate levels. Meanwhile the dynamic changes of in vivo cysteine, glutathione, and IAA levels were measured. Root cysteine, glutathione, and IAA levels are positively correlated with external sulfate levels in the physiological range, which eventually affect root system architecture. Low sulfate levels also downregulate the genes involved in auxin biosynthesis and transport, and elevate the accumulation of PLT1 and PLT2. This study suggests that sulfate level affects the primary root elongation by regulating the endogenous auxin level and root stem cell niche maintenance. © 2014 Institute of Botany, Chinese Academy of Sciences.

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

    KAUST Repository

    Chen, Hao

    2011-01-01

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

  7. Lauric acid in crown daisy root exudate potently regulates root-knot nematode chemotaxis and disrupts Mi-flp-18 expression to block infection.

    Science.gov (United States)

    Dong, Linlin; Li, Xiaolin; Huang, Li; Gao, Ying; Zhong, Lina; Zheng, Yuanyuan; Zuo, Yuanmei

    2014-01-01

    Tomato (Solanum lycopersicum) crops can be severely damaged due to parasitism by the root-knot nematode (RKN) Meloidogyne incognita, but are protected when intercropped with crown daisy (Chrysanthemum coronarium L.). Root exudate may be the determining factor for this protection. An experiment using pots linked by a tube and Petri dish experiments were undertaken to confirm that tomato-crown daisy intercropping root exudate decreased the number of nematodes and alleviated nematode damage, and to determine crown daisy root exudate-regulated nematode chemotaxis. Following a gas chromatography-mass spectrometry assay, it was found that the intercropping protection was derived from the potent bioactivity of a specific root exudate component of crown daisy, namely lauric acid. The Mi-flp-18 gene, encoding an FMRFamide-like peptide neuromodulator, regulated nematode chemotaxis and infection by RNA interference. Moreover, it was shown that lauric acid acts as both a lethal trap and a repellent for M. incognita by specifically regulating Mi-flp-18 expression in a concentration-dependent manner. Low concentrations of lauric acid (0.5-2.0mM) attract M. incognita and consequently cause death, while high concentrations (4.0mM) repel M. incognita. This study elucidates how lauric acid in crown daisy root exudate regulates nematode chemotaxis and disrupts Mi-flp-18 expression to alleviate nematode damage, and presents a general methodology for studying signalling systems affected by plant root exudates in the rhizosphere. This could lead to the development of economical and feasible strategies for controlling plant-parasitic nematodes, and provide an alternative to the use of pesticides in farming systems.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

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

    2015-04-01

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

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

    Institute of Scientific and Technical Information of China (English)

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

    2007-01-01

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

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

    Science.gov (United States)

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

    2015-12-01

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

  12. Transcriptional regulation of chlorogenic acid biosynthesis in carrot root slices exposed to UV-B light

    Science.gov (United States)

    Orange carrots are well known for their nutritional value as producers of ß-carotene, a Vitamin A precursor. Lesser known, is their ability to accumulate antioxidants such as chlorogenic acid. Chlorogenic acid is produced through the same biosynthetic pathway that produces lignins, anthocyanins, f...

  13. Transcriptional profiling of the PDR gene family in rice roots in response to plant growth regulators, redox perturbations and weak organic acid stresses.

    Science.gov (United States)

    Moons, Ann

    2008-12-01

    The role of plant pleiotropic drug resistance (PDR) type ATP-binding cassette (ABC) transporters remains poorly understood. We characterized the expression of the rice pleiotropic drug resistance (PDR) gene family in roots, where PDR transporters are believed to have major functions. A prototypical oligonucleotide array was developed containing 70-mers chosen in the gene-specific 3' untranslated regions of the rice PDR genes, other full-molecule rice ABC transporter genes and relevant marker genes. Jasmonates, which are involved in plant defense and secondary metabolism, proved major inducers of PDR gene expression. Over half of the PDR genes were JA-induced in roots of rice; OsPDR9 to the highest level. Salicylic acid, involved in plant pathogen defense, markedly induced the expression of OsPDR20. OsPDR20 was cDNA cloned and characterized. Abscisic acid, typically involved in water deficit responses, particularly induced OsPDR3 in roots and shoot and OsPDR6 in rice leaves. OsPDR9 and OsPDR20 were furthermore up-regulated in response to dithiothreitol- or glutathione-induced redox perturbations. Exogenous application of the weak organic acids lactic acid, malic acid, and citric acid differentially induced the expression of OsPDR3, OsPDR8, OsPDR9 and OsPDR20 in rice seedling roots. This transcriptional survey represents a guide for the further functional analysis of individual PDR transporters in roots of rice.

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

    Science.gov (United States)

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

    2015-01-01

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

  15. Role of cytokinin in the regulation of root gravitropism.

    Science.gov (United States)

    Aloni, Roni; Langhans, Markus; Aloni, Erez; Ullrich, Cornelia I

    2004-11-01

    The models explaining root gravitropism propose that the growth response of plants to gravity is regulated by asymmetric distribution of auxin (indole-3-acetic acid, IAA). Since cytokinin has a negative regulatory role in root growth, we suspected that it might function as an inhibitor of tropic root elongation during gravity response. Therefore, we examined the free-bioactive-cytokinin-dependent ARR5::GUS expression pattern in root tips of transformants of Arabidopsis thaliana (L.) Heynh., visualized high cytokinin concentrations in the root cap with specific monoclonal antibodies, and complemented the analyses by external application of cytokinin. Our findings show that mainly the statocytes of the cap produce cytokinin, which may contribute to the regulation of root gravitropism. The homogenous symmetric expression of the cytokinin-responsive promoter in vertical root caps rapidly changed within less than 30 min of gravistimulation into an asymmetrical activation pattern, visualized as a lateral, distinctly stained, concentrated spot on the new lower root side of the cap cells. This asymmetric cytokinin distribution obviously caused initiation of a downward curvature near the root apex during the early rapid phase of gravity response, by inhibiting elongation at the lower side and promoting growth at the upper side of the distal elongation zone closely behind the root cap. Exogenous cytokinin applied to vertical roots induced root bending towards the application site, confirming the suspected inhibitory effect of cytokinin in root gravitropism. Our results suggest that the early root graviresponse is controlled by cytokinin. We conclude that both cytokinin and auxin are key hormones that regulate root gravitropism.

  16. Auxin Influx Carrier AUX1 Confers Acid Resistance for Arabidopsis Root Elongation Through the Regulation of Plasma Membrane H+-ATPase.

    Science.gov (United States)

    Inoue, Shin-Ichiro; Takahashi, Koji; Okumura-Noda, Hiromi; Kinoshita, Toshinori

    2016-10-01

    The plant plasma membrane (PM) H(+)-ATPase regulates pH homeostasis and cell elongation in roots through the formation of an electrochemical H(+) gradient across the PM and a decrease in apoplastic pH; however, the detailed signaling for the regulation of PM H(+)-ATPases remains unclear. Here, we show that an auxin influx carrier, AUXIN RESISTANT1 (AUX1), is required for the maintenance of PM H(+)-ATPase activity and proper root elongation. We isolated a low pH-hypersensitive 1 (loph1) mutant by a genetic screen of Arabidopsis thaliana on low pH agar plates. The loph1 mutant is a loss-of-function mutant of the AUX1 gene and exhibits a root growth retardation restricted to the low pH condition. The ATP hydrolysis and H(+) extrusion activities of the PM H(+)-ATPase were reduced in loph1 roots. Furthermore, the phosphorylation of the penultimate threonine of the PM H(+)-ATPase was reduced in loph1 roots under both normal and low pH conditions without reduction of the amount of PM H(+)-ATPase. Expression of the DR5:GUS reporter gene and auxin-responsive genes suggested that endogenous auxin levels were lower in loph1 roots than in the wild type. The aux1-7 mutant roots also exhibited root growth retardation in the low pH condition like the loph1 roots. These results indicate that AUX1 positively regulates the PM H(+)-ATPase activity through maintenance of the auxin accumulation in root tips, and this process may serve to maintain root elongation especially under low pH conditions. © The Author 2016. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists.

  17. Abscisic Acid: Hidden Architect of Root System Structure

    Directory of Open Access Journals (Sweden)

    Jeanne M. Harris

    2015-08-01

    Full Text Available Plants modulate root growth in response to changes in the local environment, guided by intrinsic developmental genetic programs. The hormone Abscisic Acid (ABA mediates responses to different environmental factors, such as the presence of nitrate in the soil, water stress and salt, shaping the structure of the root system by regulating the production of lateral roots as well as controlling root elongation by modulating cell division and elongation. Curiously, ABA controls different aspects of root architecture in different plant species, perhaps providing some insight into the great diversity of root architecture in different plants, both from different taxa and from different environments. ABA is an ancient signaling pathway, acquired well before the diversification of land plants. Nonetheless, how this ancient signaling module is implemented or interacts within a larger signaling network appears to vary in different species. This review will examine the role of ABA in the control of root architecture, focusing on the regulation of lateral root formation in three plant species, Arabidopsis thaliana, Medicago truncatula and Oryza sativa. We will consider how the implementation of the ABA signaling module might be a target of natural selection, to help contribute to the diversity of root architecture in nature.

  18. Gene expression regulation in roots under drought.

    Science.gov (United States)

    Janiak, Agnieszka; Kwaśniewski, Mirosław; Szarejko, Iwona

    2016-02-01

    Stress signalling and regulatory networks controlling expression of target genes are the basis of plant response to drought. Roots are the first organs exposed to water deficiency in the soil and are the place of drought sensing. Signalling cascades transfer chemical signals toward the shoot and initiate molecular responses that lead to the biochemical and morphological changes that allow plants to be protected against water loss and to tolerate stress conditions. Here, we present an overview of signalling network and gene expression regulation pathways that are actively induced in roots under drought stress. In particular, the role of several transcription factor (TF) families, including DREB, AP2/ERF, NAC, bZIP, MYC, CAMTA, Alfin-like and Q-type ZFP, in the regulation of root response to drought are highlighted. The information provided includes available data on mutual interactions between these TFs together with their regulation by plant hormones and other signalling molecules. The most significant downstream target genes and molecular processes that are controlled by the regulatory factors are given. These data are also coupled with information about the influence of the described regulatory networks on root traits and root development which may translate to enhanced drought tolerance. This is the first literature survey demonstrating the gene expression regulatory machinery that is induced by drought stress, presented from the perspective of roots.

  19. Induction of nodD Gene in a Betarhizobium Isolate, Cupriavidus sp. of Mimosa pudica, by Root Nodule Phenolic Acids.

    Science.gov (United States)

    Mandal, Santi M; Chakraborty, Dipjyoti; Dutta, Suhrid R; Ghosh, Ananta K; Pati, Bikas R; Korpole, Suresh; Paul, Debarati

    2016-06-01

    A range of phenolic acids, viz., p-coumaric acid, 4-hydroxybenzaldehyde, 4-hydroxybenzoic acid, protocatechuic acid, caffeic acid, ferulic acid, and cinnamic acid have been isolated and identified by LC-MS analysis in the roots and root nodules of Mimosa pudica. The effects of identified phenolic acids on the regulation of nodulation (nod) genes have been evaluated in a betarhizobium isolate of M. pudica root nodule. Protocatechuic acid and p-hydroxybenzoic acid were most effective in inducing nod gene, whereas caffeic acid had no significant effect. Phenylalanine ammonia lyase, peroxidase, and polyphenol oxidase activities were estimated, indicating regulation and metabolism of phenolic acids in root nodules. These results showed that nodD gene expression of betarhizobium is regulated by simple phenolic acids such as protocatechuic acid and p-hydroxybenzoic acid present in host root nodule and sustains nodule organogenesis.

  20. Proteome Analysis of Rice Root Proteins Regulated by Gibberellin

    Institute of Scientific and Technical Information of China (English)

    Setsuko Komatsu; Hirosato Konishi

    2005-01-01

    To gain an enhanced understanding of the mechanism by which gibberellins (GAs) regulate the growth and development of plants, it is necessary to identify proteins regulated by GA. Proteome analysis techniques have been applied as a direct,effective, and reliable tool in differential protein expressions. In previous studies,sixteen proteins showed differences in accumulation levels as a result of treatment with GA3, uniconazole, or abscisic acid (ABA), and/or the differences between the GA-deficient semi-dwarf mutant, Tan-ginbozu, and normal cultivars. Among these proteins, aldolase increased in roots treated with GA3, was present at low levels in Tan-ginbozu roots, and decreased in roots treated with uniconazole or ABA. In a root elongation assay, the growth of aldolase-antisense transgenic rice was half of that of vector control transgenic rice. These results indicate that increases in aldolase activity stimulate the glycolytic pathway and may play an important role in the GA-induced growth of roots. In this review, we discuss the relationship among GA, aldolase, and root growth.

  1. Effects of acid deposition on tree roots

    Energy Technology Data Exchange (ETDEWEB)

    Persson, H. [Swedish Univ. of Agricultural Sciences (Sweden). Dept. of Ecology and Environmental Research

    1995-12-31

    Large forest regions in SW Sweden have been exposed to high levels of acid deposition for many decades, causing soil acidification in forest soils. Historically, SO{sub 2} has been the major acidification agent, but lately nitrogen compounds increasingly have become important. The amount and chemical form of nitrogen strongly affects the pH in the rhizosphere and rhizoplane. Many forest stands show a positive growth response to increased nitrogen input, even in heavily N-loaded areas. Nitrogen fertilization experiments suggest that part of the increased forest production is caused by a translocation of biomass production from below-ground to above-ground parts. At the same time fine-root growth dynamics are strongly affected by the high N supply. Deficiencies of various nutrients (Mg,Ca,K,Mn and Zn) obtained from needle analyses have been reported from different Picea abies stands. In areas with more extensive acidification and nutrient leaching, a decline in tree vitality has been observed. Although deficiency symptoms in forest trees may be reflected in nitrogen/cation ratios in fine roots, few attempts have been made to explain forest damage symptoms from fine-root chemistry. Root damage is often described as a decline in the amount of living fine roots, an increase in the amount of dead versus live fine roots (a lower live/dead ratio) and an increasing amount of dead medium and coarse roots. The primary objectives of the present presentation were to analyse available data on the effects of high nitrogen and sulphur deposition on mineral nutrient balance in tree fine roots and to evaluate the risk of Al interference with cation uptake by roots

  2. Acid tolerance in root nodule bacteria.

    Science.gov (United States)

    Glenn, A R; Reeve, W G; Tiwari, R P; Dilworth, M J

    1999-01-01

    Biological nitrogen fixation, especially via the legume Rhizobium symbiosis, is important for world agriculture. The productivity of legume crops and pastures is significantly affected by soil acidity; in some cases it is the prokaryotic partner that is pH sensitive. Growth of Rhizobium is adversely affected by low pH, especially in the 'acid stress zone'. Rhizobia exhibit an adaptive acid tolerance response (ATR) that is influenced by calcium concentration. Using Tn5-mutagenesis, gusA fusions and 'proteome' analysis, we have identified a range of genes that are essential for growth at low pH (such as actA, actP, exoR, actR and actS). At least three regulatory systems exist. The two-component sensor-regulator system, actSR, is essential for induction of the adaptive ATR. Two other regulatory circuits exist that are independent of ActR. One system involves the low pH-induced regulator gene, phrR, which may control other low pH-regulated genes. The other circuit, involving a regulator that is yet unidentified, controls the expression of a pH-regulated structural gene (lpiA). We have used pH-responsive gusA fusions to identify acid-inducible genes (such as lpiA), and then attempted to identify the regulators of these genes. The emerging picture is of a relatively complex set of systems that respond to external pH.

  3. Rooting depths regulate the global water cycle

    Science.gov (United States)

    Miguez-Macho, Gonzalo; Fan, Ying

    2017-04-01

    Ecosystem productivity and evapotranspiration fluxes are fundamental regulators of the global carbon and water cycles. Where and how much plants grow is largely determined by atmospheric conditions and soil water availability. It is the reliance of ecosystems on soil water that links their fate tightly to precipitation and groundwater reach. Here, we explore the controls on plant root uptake imposed by climate at the large scale and by groundwater accessibility at the local drainage scale, aiming to untangle the spatial and temporal global patterns of rain-fed and groundwater-fed ecosystems. To this end, we use observed atmospheric and productivity conditions to model the seasonal evolution of root uptake and soil moisture profiles and their coupling to the water table, with a global groundwater-soil-vegetation framework at the 1km resolution. Results indicate highly variable uptake-depth across seasonal and local hydrologic gradients, and a far more common occurrence of deep (>5m) uptake than previous thought. Implications to future environmental change are briefly discussed.

  4. Role of Ascorbate in the Regulation of the Arabidopsis thaliana Root Growth by Phosphate Availability

    Directory of Open Access Journals (Sweden)

    Jarosław Tyburski

    2012-01-01

    Full Text Available Arabidopsis root system responds to phosphorus (P deficiency by decreasing primary root elongation and developing abundant lateral roots. Feeding plants with ascorbic acid (ASC stimulated primary root elongation in seedlings grown under limiting P concentration. However, at high P, ASC inhibited root growth. Seedlings of ascorbate-deficient mutant (vtc1 formed short roots irrespective of P availability. P-starved plants accumulated less ascorbate in primary root tips than those grown under high P. ASC-treatment stimulated cell divisions in root tips of seedlings grown at low P. At high P concentrations ASC decreased the number of mitotic cells in the root tips. The lateral root density in seedlings grown under P deficiency was decreased by ASC treatments. At high P, this parameter was not affected by ASC-supplementation. vtc1 mutant exhibited increased lateral root formation on either, P-deficient or P-sufficient medium. Irrespective of P availability, high ASC concentrations reduced density and growth of root hairs. These results suggest that ascorbate may participate in the regulation of primary root elongation at different phosphate availability via its effect on mitotic activity in the root tips.

  5. The bHLH transcription factor SPATULA regulates root growth by controlling the size of the root meristem

    Directory of Open Access Journals (Sweden)

    Makkena Srilakshmi

    2013-01-01

    Full Text Available Abstract Background The Arabidopsis thaliana gene SPATULA (SPT, encoding a bHLH transcription factor, was originally identified for its role in pistil development. SPT is necessary for the growth and development of all carpel margin tissues including the style, stigma, septum and transmitting tract. Since then, it has been shown to have pleiotropic roles during development, including restricting the meristematic region of the leaf primordia and cotyledon expansion. Although SPT is expressed in roots, its role in this organ has not been investigated. Results An analysis of embryo and root development showed that loss of SPT function causes an increase in quiescent center size in both the embryonic and postembryonic stem cell niches. In addition, root meristem size is larger due to increased division, which leads to a longer primary root. spt mutants exhibit other pleiotropic developmental phenotypes, including more flowers, shorter internodes and an extended flowering period. Genetic and molecular analysis suggests that SPT regulates cell proliferation in parallel to gibberellic acid as well as affecting auxin accumulation or transport. Conclusions Our data suggest that SPT functions in growth control throughout sporophytic growth of Arabidopsis, but is not necessary for cell fate decisions except during carpel development. SPT functions independently of gibberellic acid during root development, but may play a role in regulating auxin transport or accumulation. Our data suggests that SPT plays a role in control of root growth, similar to its roles in above ground tissues.

  6. Gibberellins regulate lateral root formation in Populus through interactions with auxin and other hormones.

    Science.gov (United States)

    Gou, Jiqing; Strauss, Steven H; Tsai, Chung Jui; Fang, Kai; Chen, Yiru; Jiang, Xiangning; Busov, Victor B

    2010-03-01

    The role of gibberellins (GAs) in regulation of lateral root development is poorly understood. We show that GA-deficient (35S:PcGA2ox1) and GA-insensitive (35S:rgl1) transgenic Populus exhibited increased lateral root proliferation and elongation under in vitro and greenhouse conditions, and these effects were reversed by exogenous GA treatment. In addition, RNA interference suppression of two poplar GA 2-oxidases predominantly expressed in roots also decreased lateral root formation. GAs negatively affected lateral root formation by inhibiting lateral root primordium initiation. A whole-genome microarray analysis of root development in GA-modified transgenic plants revealed 2069 genes with significantly altered expression. The expression of 1178 genes, including genes that promote cell proliferation, growth, and cell wall loosening, corresponded to the phenotypic severity of the root traits when transgenic events with differential phenotypic expression were compared. The array data and direct hormone measurements suggested crosstalk of GA signaling with other hormone pathways, including auxin and abscisic acid. Transgenic modification of a differentially expressed gene encoding an auxin efflux carrier suggests that GA modulation of lateral root development is at least partly imparted by polar auxin transport modification. These results suggest a mechanism for GA-regulated modulation of lateral root proliferation associated with regulation of plant allometry during the stress response.

  7. Melatonin regulates root meristem by repressing auxin synthesis and polar auxin transport in Arabidopsis

    Directory of Open Access Journals (Sweden)

    Qiannan Wang

    2016-12-01

    Full Text Available Melatonin (N-acetyl-5-methoxytryptamine plays important roles in regulating both biotic and abiotic stress tolerance, biological rhythms, plant growth and development. Sharing the same substrate (tryptophan for the biosynthesis, melatonin and auxin also have similar effects in plant development. However, the specific function of melatonin in modulating plant root growth and the relationship between melatonin and auxin as well as underlying mechanisms are still unclear. In this study, we found high concentration of melatonin remarkably inhibited root growth in Arabidopsis by reducing root meristem size. Further studies showed that melatonin negatively regulated auxin biosynthesis, the expression of PINFORMED (PIN proteins as well as auxin response in Arabidopsis. Moreover, the root growth of the triple mutant pin1pin3pin7 was more tolerant than that of wild type in response to melatonin treatment, suggesting the essential role of PIN1/3/7 in melatonin-mediated root growth. Combination treatment of melatonin and 5-Triiodobenzoic acid (TIBA did not enhance melatonin-mediated reduction of root meristem size, indicating that polar auxin transport (PAT may be necessary for the regulation of root meristem size by melatonin treatment. Taken together, this study indicates that melatonin regulates root growth in Arabidopsis, through auxin synthesis and polar auxin transport, at least partially.

  8. Melatonin Regulates Root Meristem by Repressing Auxin Synthesis and Polar Auxin Transport in Arabidopsis.

    Science.gov (United States)

    Wang, Qiannan; An, Bang; Wei, Yunxie; Reiter, Russel J; Shi, Haitao; Luo, Hongli; He, Chaozu

    2016-01-01

    Melatonin (N-acetyl-5-methoxytryptamine) plays important roles in regulating both biotic and abiotic stress tolerance, biological rhythms, plant growth and development. Sharing the same substrate (tryptophan) for the biosynthesis, melatonin and auxin also have similar effects in plant development. However, the specific function of melatonin in modulating plant root growth and the relationship between melatonin and auxin as well as underlying mechanisms are still unclear. In this study, we found high concentration of melatonin remarkably inhibited root growth in Arabidopsis by reducing root meristem size. Further studies showed that melatonin negatively regulated auxin biosynthesis, the expression of PINFORMED (PIN) proteins as well as auxin response in Arabidopsis. Moreover, the root growth of the triple mutant pin1pin3pin7 was more tolerant than that of wild-type in response to melatonin treatment, suggesting the essential role of PIN1/3/7 in melatonin-mediated root growth. Combination treatment of melatonin and 5-Triiodobenzoic acid (TIBA) did not enhance melatonin-mediated reduction of root meristem size, indicating that polar auxin transport (PAT) may be necessary for the regulation of root meristem size by melatonin treatment. Taken together, this study indicates that melatonin regulates root growth in Arabidopsis, through auxin synthesis and polar auxin transport, at least partially.

  9. 75 FR 30300 - Drawbridge Operation Regulations; Root River, Racine, WI

    Science.gov (United States)

    2010-06-01

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF HOMELAND SECURITY Coast Guard 33 CFR Part 117 Drawbridge Operation Regulations; Root River, Racine, WI AGENCY: Coast... Street Bridge at Mile 0.31 and the State Street Bridge at Mile 0.53 over the Root River, at Racine,...

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

    Institute of Scientific and Technical Information of China (English)

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

    2007-01-01

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

  11. Acid protease production in fungal root endophytes.

    Science.gov (United States)

    Mayerhofer, Michael S; Fraser, Erica; Kernaghan, Gavin

    2015-01-01

    Fungal endophytes are ubiquitous in healthy root tissue, but little is known about their ecosystem functions, including their ability to utilize organic nutrient sources such as proteins. Root-associated fungi may secrete proteases to access the carbon and mineral nutrients within proteins in the soil or in the cells of their plant host. We compared the protein utilization patterns of multiple isolates of the root endophytes Phialocephala fortinii s.l., Meliniomyces variabilis and Umbelopsis isabellina with those of two ectomycorrhizal (ECM) fungi, Hebeloma incarnatulum and Laccaria bicolor, and the wood-decay fungus Irpex lacteus at pH values of 2-9 on liquid BSA media. We also assessed protease activity using a fluorescently labeled casein assay and gelatin zymography and characterized proteases using specific protease inhibitors. I. lacteus and U. isabellina utilized protein efficiently, while the ECM fungi exhibited poor protein utilization. ECM fungi secreted metallo-proteases and had pH optima above 4, while other fungi produced aspartic proteases with lower pH optima. The ascomycetous root endophytes M. variabilis and P. fortinii exhibited intermediate levels of protein utilization and M. variabilis exhibited a very low pH optimum. Comparing proteolytic profiles between fungal root endophytes and fungi with well defined ecological roles provides insight into the ecology of these cryptic root associates.

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

    Directory of Open Access Journals (Sweden)

    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.

  13. Cytokinin producing bacteria stimulate amino acid deposition by wheat roots.

    Science.gov (United States)

    Kudoyarova, Guzel R; Melentiev, Alexander I; Martynenko, Elena V; Timergalina, Leila N; Arkhipova, Tatiana N; Shendel, Galina V; Kuz'mina, Ludmila Yu; Dodd, Ian C; Veselov, Stanislav Yu

    2014-10-01

    Phytohormone production is one mechanism by which rhizobacteria can stimulate plant growth, but it is not clear whether the bacteria gain from this mechanism. The hypothesis that microbial-derived cytokinin phytohormones stimulate root exudation of amino acids was tested. The rhizosphere of wheat plants was drenched with the synthetic cytokinin trans-zeatin or inoculated with Bacillus subtilis IB-22 (which produces zeatin type cytokinins) or B. subtilis IB-21 (which failed to accumulate cytokinins). Growing plants in a split root system allowed spatial separation of zeatin application or rhizobacterial inoculation to one compartment and analyses of amino acid release from roots (rhizodeposition) into the other compartment (without either microbial inoculation or treatment with exogenous hormone). Supplying B. subtilis IB-22 or zeatin to either the whole root system or half of the roots increased concentrations of amino acids in the soil solution although the magnitude of the increase was greater when whole roots were treated. There was some similarity in amino acid concentrations induced by either bacterial or zeatin treatment. Thus B. subtilis IB-22 increased amino acid rhizodeposition, likely due to its ability to produce cytokinins. Furthermore, B. subtilis strain IB-21, which failed to accumulate cytokinins in culture media, did not significantly affect amino acid concentrations in the wheat rhizosphere. The ability of rhizobacteria to produce cytokinins and thereby stimulate rhizodeposition may be important in enhancing rhizobacterial colonization of the rhizoplane.

  14. Caffeoylquinic Acids in Storage Roots of Sixteen Sweetpotato Genotypes

    Science.gov (United States)

    The contents of chlorogenic acid and the 3,4-, 3,5- and 4,5- isomers of dicaffeoylquinic acid (DCQA) in the storage root tissues of sixteen sweetpotato genotypes were determined. Averaged over genotypes, the contents of the four compounds were highest in the cortex, intermediate in the stele and lo...

  15. Cinnamic acid increases lignin production and inhibits soybean root growth.

    Directory of Open Access Journals (Sweden)

    Victor Hugo Salvador

    Full Text Available Cinnamic acid is a known allelochemical that affects seed germination and plant root growth and therefore influences several metabolic processes. In the present work, we evaluated its effects on growth, indole-3-acetic acid (IAA oxidase and cinnamate 4-hydroxylase (C4H activities and lignin monomer composition in soybean (Glycine max roots. The results revealed that exogenously applied cinnamic acid inhibited root growth and increased IAA oxidase and C4H activities. The allelochemical increased the total lignin content, thus altering the sum and ratios of the p-hydroxyphenyl (H, guaiacyl (G, and syringyl (S lignin monomers. When applied alone or with cinnamic acid, piperonylic acid (PIP, a quasi-irreversible inhibitor of C4H reduced C4H activity, lignin and the H, G, S monomer content compared to the cinnamic acid treatment. Taken together, these results indicate that exogenously applied cinnamic acid can be channeled into the phenylpropanoid pathway via the C4H reaction, resulting in an increase in H lignin. In conjunction with enhanced IAA oxidase activity, these metabolic responses lead to the stiffening of the cell wall and are followed by a reduction in soybean root growth.

  16. Evolutionary roots of arginase expression and regulation

    Directory of Open Access Journals (Sweden)

    Jolanta Maria Dzik

    2014-11-01

    Full Text Available Two main types of macrophage functions are known: classical (M1, producing nitric oxide, NO, and M2, in which arginase activity is primarily expressed. Ornithine, the product of arginase, is a substrate for synthesis of polyamines and collagen, important for growth and ontogeny of animals. M2 macrophages, expressing high level of mitochondrial arginase, have been implicated in promoting cell division and deposition of collagen during ontogeny and wound repair. Arginase expression is the default mode of tissue macrophages, but can also be amplified by signals, such as IL4/13 or TGF-β that accelerates wound healing and tissue repair. In worms, the induction of collagen gene is coupled with induction of immune response genes, both depending on the same TGF-β-like pathway. This suggests that the main function of M2 heal type macrophages is originally connected with the TGF-β superfamily of proteins, which are involved in regulation of tissue and organ differentiation in embryogenesis. Excretory-secretory products of metazoan parasites are able to induce M2 type of macrophage responses promoting wound healing without participation of Th2 cytokines IL4/IL13. The expression of arginase in lower animals can be induced by the presence of parasite antigens and TGF-β signals leading to collagen synthesis. This also means that the main proteins, which, in primitive metazoans, are involved in regulation of tissue and organ differentiation in embryogenesis are produced by innate immunity. The signaling function of NO is known already from the sponge stage of animal evolution. The cytotoxic role of NO molecule appeared later, as documented in immunity of marine mollusks and some insects. This implies that the M2-wound healing promoting function predates the defensive role of NO, a characteristic of M1 macrophages. Understanding when and how the M1 and M2 activities came to be in animals is useful for understanding how macrophage immunity, and immune

  17. A plant microRNA regulates the adaptation of roots to drought stress

    KAUST Repository

    Chen, Hao

    2012-06-01

    Plants tend to restrict their horizontal root proliferation in response to drought stress, an adaptive response mediated by the phytohormone abscisic acid (ABA) in antagonism with auxin through unknown mechanisms. Here, we found that stress-regulated miR393-guided cleavage of the transcripts encoding two auxin receptors, TIR1 and AFB2, was required for inhibition of lateral root growth by ABA or osmotic stress. Unlike in the control plants, the lateral root growth of seedlings expressing miR393-resistant TIR1 or AFB2 was no longer inhibited by ABA or osmotic stress. Our results indicate that miR393-mediated attenuation of auxin signaling modulates root adaptation to drought stress. © 2012 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

  18. Auxin regulates distal stem cell differentiation in Arabidopsis roots.

    Science.gov (United States)

    Ding, Zhaojun; Friml, Jirí

    2010-06-29

    The stem cell niche in the root meristem is critical for the development of the plant root system. The plant hormone auxin acts as a versatile trigger in many developmental processes, including the regulation of root growth, but its role in the control of the stem cell activity remains largely unclear. Here we show that local auxin levels, determined by biosynthesis and intercellular transport, mediate maintenance or differentiation of distal stem cells in the Arabidopsis thaliana roots. Genetic analysis shows that auxin acts upstream of the major regulators of the stem cell activity, the homeodomain transcription factor WOX5, and the AP-2 transcription factor PLETHORA. Auxin signaling for differentiation of distal stem cells requires the transcriptional repressor IAA17/AXR3 as well as the ARF10 and ARF16 auxin response factors. ARF10 and ARF16 activities repress the WOX5 transcription and restrict it to the quiescent center, where WOX5, in turn, is needed for the activity of PLETHORA. Our investigations reveal that long-distance auxin signals act upstream of the short-range network of transcriptional factors to mediate the differentiation of distal stem cells in roots.

  19. Influence of simulated acidic rain on root-infecting fungi

    Energy Technology Data Exchange (ETDEWEB)

    Shafer, S.R.

    1983-01-01

    Influences of the acidity of simulated rain on root-infecting fungi were investigated. Effects of rain acidity on Phytophthora cinnamomi were studied. Propagule densities in soil depended upon the acidity (pH 5.6, 4.0, 3.2, or 2.4) of simulated rain and soil depth (1, 2, 4, or 8 cm). Lowest densities occurred in 1 to 2 cm soil layers exposed to rains at pH 3.2 or 2.4. Sporangium production on radicles of Lupinus angustifolius in Lakeland sand moistened with rain solution at pH 2.4 was 47% less than production with solution at pH 5.6. A linear response to solution acidity was exhibited. Infection of L. angustifolius roots by zoospores demonstrated a linear response to acidity of rain. Approximately 44% fewer lesions occurred on roots of seedlings exposed to rain at pH 2.4 than on roots of seedlings exposed to rain at pH 5.6. The acidity (pH 5.6, 4.0, 3.2, or 2.4) of repeated rains had no consistent effect on disease progress among L. augustifolius seedlings planted in infested soil. The formation of ectomycorrhizae on Pinus taeda seedlings exhibited a quadratic response to acidity of repeated rains. The percentage of short roots that were ectomycorrhizal was greatest among seedlings exposed to rains at pH 2.4 and least among seedlings exposed to rains at pH 4.0. The density of Macrophomina phaseolina propagules in Lakeland sand exposed to repeated rains at pH 2.4 was an average of 20% less than densities associated with rains at pH 5.6, 4.0, or 3.2.

  20. Regulation of Shoot and Root Development through Mutual Signaling

    Institute of Scientific and Technical Information of China (English)

    Jér(o)me Puig; Germain Pauluzzi; Emmanuel Guiderdoni; Pascal Gantet

    2012-01-01

    Plants adjust their development in relation to the availability of nutrient sources.This necessitates signaling between root and shoot.Aside from the well-known systemic signaling processes mediated by auxin,cytokinin,and sugars,new pathways involving carotenoid-derived hormones have recently been identified.The auxin-responsive MAX pathway controls shoot branching through the biosynthesis of strigolactone in the roots.The BYPASS1 gene affects the production of an as-yet unknown carotenoid-derived substance in roots that promotes shoot development.Novel local and systemic mechanisms that control adaptive root development in response to nitrogen and phosphorus starvation were recently discovered.Notably,the ability of the NITRATE TRANSPORTER 1.1 to transport auxin drew for the first time a functional link between auxin,root development,and nitrate availability in soil.The study of plant response to phosphorus starvation allowed the identification of a systemic mobile miRNA.Deciphering and integrating these signaling pathways at the whole-plant level provide a new perspective for understanding how plants regulate their development in response to environmental cues.

  1. PHYTOCHROME KINASE SUBSTRATE1 regulates root phototropism and gravitropism.

    Science.gov (United States)

    Boccalandro, Hernán E; De Simone, Silvia N; Bergmann-Honsberger, Ariane; Schepens, Isabelle; Fankhauser, Christian; Casal, Jorge J

    2008-01-01

    Light promotes the expression of PHYTOCHROME KINASE SUBSTRATE1 (PKS1) in the root of Arabidopsis thaliana, but the function of PKS1 in this organ is unknown. Unilateral blue light induced a negative root phototropic response mediated by phototropin 1 in wild-type seedlings. This response was absent in pks1 mutants. In the wild type, unilateral blue light enhanced PKS1 expression in the subapical region of the root several hours before bending was detectable. The negative phototropism and the enhanced PKS1 expression in response to blue light required phytochrome A (phyA). In addition, the pks1 mutation enhanced the root gravitropic response when vertically oriented seedlings were placed horizontally. The negative regulation of gravitropism by PKS1 occurred even in dark-grown seedlings and did not require phyA. Blue light also failed to induce negative phototropism in pks1 under reduced gravitational stimulation, indicating that the effect of pks1 on phototropism is not simply the consequence of the counteracting effect of enhanced gravitropism. We propose a model where the background level of PKS1 reduces gravitropism. After a phyA-dependent increase in its expression, PKS1 positively affects root phototropism and both effects contribute to negative curvature in response to unilateral blue light.

  2. The cytochemical localization of ascorbic acid in root tip cells.

    Science.gov (United States)

    JENSEN, W A; KAVALJIAN, L G

    1956-01-25

    The intracellular distribution of ascorbic acid was studied in frozen-dried root tips of Allium cepa and Vicia faba by the silver nitrate procedure. The sites of the ascorbic acid as indicated by the deposited silver appear as spherical (0.2 to 0.6 micro in diameter) cytoplasmic particles. The site appears to have small amounts of lipides and to be rich in ribonucleic acid. These particles are concluded to be submicroscopic in size and associated, in the elongating cell, with the cell surface. In the meristematic cells they appear fewer in number and are distributed throughout the cytoplasm.

  3. Alterations in cytosol free calcium in horseradish roots simultaneously exposed to lanthanum(III) and acid rain.

    Science.gov (United States)

    Zhang, Xuanbo; Wang, Lihong; Zhou, Anhua; Zhou, Qing; Huang, Xiaohua

    2016-04-01

    The extensive use of rare earth elements (REEs) has increased their environmental levels. REE pollution concomitant with acid rain in many agricultural regions can affect crop growth. Cytosol free calcium ions (Ca(2+)) play an important role in almost all cellular activities. However, no data have been reported regarding the role of cytosol free Ca(2+) in plant roots simultaneously exposed to REE and acid rain. In this study, the effects of exposures to lanthanum(III) and acid rain, independently and in combination, on cytosol free Ca(2+) levels, root activity, metal contents, biomass, cytosol pH and La contents in horseradish roots were investigated. The simultaneous exposures to La(III) and acid rain increased or decreased the cytosol free Ca(2+) levels, depending on the concentration of La(III), and these effects were more evident than independent exposure to La(III) or acid rain. In combined exposures, cytosol free Ca(2+) played an important role in the regulation of root activity, metal contents and biomass. These roles were closely related to La(III) dose, acid rain strength and treatment mode (independent exposure or simultaneous exposure). A low concentration of La(III) (20 mg L(-1)) could alleviate the adverse effects on the roots caused by acid rain, and the combined exposures at higher concentrations of La(III) and acid rain had synergic effects on the roots.

  4. Acclimation of croton and hibiscus seedlings in response to the application of indobultiric acid and humic acid for rooting

    Directory of Open Access Journals (Sweden)

    Lílian Estrela Borges Baldotto

    2015-06-01

    Full Text Available The vegetative propagation of ornamental plants can be accelerated by applying plant growth regulators. Amongst them, the use of auxins, plant hormones with physiological effects on cell elongation and rooting have stood out. Alternatively, the application of humic acids, bioactive fraction of soil organic matter, also results in increases in rooting cuttings of ornamental plants. The objective of this work was to study the growth characteristics and the nutritional contents of croton and hibiscus plants during acclimation of seedlings in response to different concentrations of indolebutyric acid (IBA and humic acid (HA applied to cuttings for rooting. The experiment was conducted in greenhouse, and the apical stem cuttings were treated with solutions with concentrations of 0, 250, 500, 1000 and 2000 mg L-1of IBA and 0, 10, 20, 30 and 40 mg L-1 of C from HA. At 45 days of rooting in carbonized rice husk, they were individually transferred to plastic bags of 2.0 dm3 containing a mixture of soil: sand: manure (2: 1: 1 as substrate. At 90 days of acclimation, the plants were collected for measurement of growth and nutritional variables. The results showed that the application of the IBA stimulates the absorption of nutrients and growth of croton cuttings and transplanted hibiscus, contributing to formation of vigorous seedlings. A similar response occurred with the application of HA in hibiscus cuttings

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

    Science.gov (United States)

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

    2013-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Zongsuo Liang

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

  7. Regulation of sesquiterpenoid metabolism in recombinant and elicited Valeriana officinalis hairy roots.

    Science.gov (United States)

    Ricigliano, Vincent; Kumar, Santosh; Kinison, Scott; Brooks, Christopher; Nybo, S Eric; Chappell, Joe; Howarth, Dianella G

    2016-05-01

    The medicinal properties of Valerian (Valeriana officinalis) root preparations are attributed to the anxiolytic sesquiterpenoid valerenic acid and its biosynthetic precursors valerenal and valerenadiene, as well as the anti-inflammatory sesquiterpenoid β-caryophyllene. In order to study and engineer the biosynthesis of these pharmacologically active metabolites, a binary vector co-transformation system was developed for V. officinalis hairy roots. The relative expression levels and jasmonate-inducibility of a number of genes associated with sesquiterpenoid metabolism were profiled in roots: farnesyl pyrophosphate synthase (VoFPS), valerendiene synthase (VoVDS), germacrene C synthase (VoGCS), and a cytochrome P450 (CYP71D442) putatively associated with terpene metabolism based on sequence homology. Recombinant hairy root lines overexpressing VoFPS or VoVDS were generated and compared to control cultures. Overexpression of the VoFPS cDNA increased levels of the corresponding transcript 4- to 8-fold and sesquiterpene hydrocarbon accumulation by 1.5- to 4-fold. Overexpression of the VoVDS cDNA increased the corresponding transcript levels 5- to 9-fold and markedly increased yields of the oxygenated sesquiterpenoids valerenic acid and valerenal. Our findings suggest that the availability of cytoplasmic farnesyl diphosphate and valerenadiene are potential bottlenecks in Valeriana-specific sesquiterpenoid biosynthesis, which is also subject to regulation by methyl jasmonate elicitation.

  8. Sugar-mediated semidian oscillation of gene expression in the cassava storage root regulates starch synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Jansson, Christer; Baguma, Yona; Sun, Chuanxin; Boren, Mats; Olsson, Helena; Rosenqvist, Sara; Mutisya, Joel; Rubaihayo, Patrick R.; Jansson, Christer

    2008-01-15

    Starch branching enzyme (SBE) activity in the cassava storage root exhibited a diurnal fluctuation, dictated by a transcriptional oscillation of the corresponding SBE genes. The peak of SBE activity coincided with the onset of sucrose accumulation in the storage, and we conclude that the oscillatory mechanism keeps the starch synthetic apparatus in the storage root sink in tune with the flux of sucrose from the photosynthetic source. When storage roots were uncoupled from the source, SBE expression could be effectively induced by exogenous sucrose. Turanose, a sucrose isomer that cannot be metabolized by plants, mimicked the effect of sucrose, demonstrating that downstream metabolism of sucrose was not necessary for signal transmission. Also glucose and glucose-1-P induced SBE expression. Interestingly, induction by sucrose, turanose and glucose but not glucose-1-P sustained an overt semidian (12-h) oscillation in SBE expression and was sensitive to the hexokinase (HXK) inhibitor glucosamine. These results suggest a pivotal regulatory role for HXK during starch synthesis. Abscisic acid (ABA) was another potent inducer of SBE expression. Induction by ABA was similar to that of glucose-1-P in that it bypassed the semidian oscillator. Both the sugar and ABA signaling cascades were disrupted by okadaic acid, a protein phosphatase inhibitor. Based on these findings, we propose a model for sugar signaling in regulation of starch synthesis in the cassava storage root.

  9. Organic acid effect on calcium uptake by the wheat roots

    Directory of Open Access Journals (Sweden)

    Fabrize Caroline Nunes

    2009-02-01

    Full Text Available This work evaluated the effect of the natural organic acids on the uptake of Ca by the wheat roots in a hydroponic solution. The following organic acids were evaluated: citric, oxalic, tartaric, malic, malonic, maleic, DL-malic, p-hydroxybenzoic, aconitic, and salicilic. The organic acids neither enhanced the root growth nor increased Ca uptake. The salicilic and malic acids were highly toxic and decreased the root growth. The citric, tartaric, maleic, aconitic, and salicilic decreased the Ca uptake by the roots due to their higher capacity to form the stable complexes with Ca in solution at pH 6.0. Decreasing the Ca valence from Ca++ to CaL+ or CaL2(0 through the organic ligand complexation reactions decreased the Ca uptake. The results suggested that the wheat roots do not absorb Ca-organic complexes.Ácidos orgânicos possuem grupos funcionais com cargas negativas que complexam íons metálicos em solução. Este trabalho avaliou o efeito de ácidos orgânicos naturais na absorção de Ca pelas raízes de trigo. Foram avaliados os seguintes ácidos orgânicos: cítrico, oxálico, tartarico, málico, malônico, maleico, DL-málico, p-hidroxibenzoico, aconítico e salicílico. Os ácidos orgânicos não estimularam o crescimento das raízes e não aumentaram a absorção de Ca. Os ácidos salicílico e maleico diminuíram drasticamente o crescimento radicular. Os ácidos cítrico, tartárico, maleico, aconítico e salicílico diminuíram a absorção de Ca pelas raízes devido à maior capacidade de formar complexos estáveis com Ca em solução no pH 6,0. A redução da valência de Ca++ para CaL+ e CaL2(0, através das reações de complexação, diminuiu a absorção de Ca pelas raízes. Os resultados sugerem que os complexos de Ca-orgânico não são absorvidos pelas raízes de trigo.

  10. Micropropagation of Salvia wagneriana Polak and hairy root cultures with rosmarinic acid production.

    Science.gov (United States)

    Ruffoni, Barbara; Bertoli, Alessandra; Pistelli, Laura; Pistelli, Luisa

    2016-01-04

    Salvia wagneriana Polak is a tropical species native to Central America, well adapted to grow in the Mediterranean basin for garden decoration. Micropropagation has been assessed from axillary shoots of adult plants using a Murashige and Skoog basal medium, with the addition of 1.33-μM 6-benzylaminopurine for shoot proliferation; the subsequent rooting phase occurred in plant growth regulator-free medium. The plants were successfully acclimatised with high survival frequency. Hairy roots were induced after co-cultivation of leaf lamina and petiole fragments with Agrobacterium rhizogenes and confirmed by PCR. The establishment and proliferation of the selected HRD3 line were obtained in hormone-free liquid medium and the production of rosmarinic acid (RA) was evaluated after elicitation. The analysis of RA was performed by LC-ESI-DAD-MS in the hydroalcoholic extracts. The addition of casein hydrolysate increased the RA production, whereas no enrichment was observed after the elicitation with jasmonic acid.

  11. Rapid shoot‐to‐root signalling regulates root hydraulic conductance via aquaporins

    National Research Council Canada - National Science Library

    VANDELEUR, REBECCA K; SULLIVAN, WENDY; ATHMAN, ASMINI; JORDANS, CHARLOTTE; GILLIHAM, MATTHEW; KAISER, BRENT N; TYERMAN, STEPHEN D

    2014-01-01

    Investigating the relationship between transpiration and root hydraulic conductance Vandeleur et al report that leaf area reduction reduces root hydraulic conductance in grapevine, soybean and maize...

  12. Metabolism and root exudation of organic acid anions under aluminium stress

    NARCIS (Netherlands)

    Mariano, E.D.; Jorge, R.A.; Keltjens, W.G.; Menossi, M.

    2005-01-01

    Numerous plant species can release organic acid anions (OA) from their roots in response to toxic aluminium (Al) ions present in the rooting medium. Hypothetically OA complex Al in the root apoplast and/or rhizosphere and thus avoid its interaction with root cellular components and its entry in the

  13. Bile acids in regulation of intestinal physiology.

    LENUS (Irish Health Repository)

    Keating, Niamh

    2009-10-01

    In addition to their roles in facilitating lipid digestion and absorption, bile acids are recognized as important regulators of intestinal function. Exposure to bile acids can dramatically influence intestinal transport and barrier properties; in recent years, they have also become appreciated as important factors in regulating cell growth and survival. Indeed, few cells reside within the intestinal mucosa that are not altered to some degree by exposure to bile acids. The past decade saw great advances in the knowledge of how bile acids exert their actions at the cellular and molecular levels. In this review, we summarize the current understanding of the role of bile acids in regulation of intestinal physiology.

  14. Amino acids as regulators of gene expression

    Directory of Open Access Journals (Sweden)

    Kimball SR

    2004-08-01

    Full Text Available The role of amino acids as substrates for protein synthesis is well documented. However, a function for amino acids in modulating the signal transduction pathways that regulate mRNA translation has only recently been described. Interesting, some of the signaling pathways regulated by amino acids overlap with those classically associated with the cellular response to hormones such as insulin and insulin-like growth factors. The focus of this review is on the signaling pathways regulated by amino acids, with a particular emphasis on the branched-chain amino acid leucine, and the steps in mRNA translation controlled by the signaling pathways.

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

    Science.gov (United States)

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

    1987-11-01

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

  16. Phytic acid: an alternative root canal chelating agent.

    Science.gov (United States)

    Nassar, Mohannad; Hiraishi, Noriko; Tamura, Yukihiko; Otsuki, Masayuki; Aoki, Kazuhiro; Tagami, Junji

    2015-02-01

    The objectives of this study were to investigate the effect of phytic acid, inositol hexakisphosphate (IP6), as a final rinse on the surface of instrumented root canals and smear-layered flat dentin surfaces treated with sodium hypochlorite (NaOCl) and to evaluate its effect on the viability and alkaline phosphatase activity of osteoblast-like cells (MC3T3-E1). The universally accepted chelating agent EDTA was used as the control in all conducted experiments. Root canals of human canines were instrumented with rotary files and irrigated with 5% NaOCl, followed by a final rinse of 17% EDTA (1 minute), 1% IP6 (1 minute or 30 seconds), or distilled water. NaOCl-treated flat coronal dentin surfaces were also treated with 17% EDTA (1 minute), 1% IP6 (1 minute or 30 seconds), or distilled water. The presence or absence of smear layer was evaluated with scanning electron microscopy. Cell viability and alkaline phosphatase assays were performed to evaluate the effect of IP6 and EDTA on cultured MC3T3-E1 cells. The results demonstrated the ability of IP6 to remove the smear layer from instrumented root canals and flat coronal dentin surfaces. When compared with EDTA, IP6 was less cytotoxic and did not affect the differentiation of MC3T3-E1 cells. IP6 shows the potential to be an effective and biocompatible chelating agent. Copyright © 2015 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  17. Citramalic acid and salicylic acid in sugar beet root exudates solubilize soil phosphorus

    Directory of Open Access Journals (Sweden)

    Karlovsky Petr

    2011-08-01

    Full Text Available Abstract Background In soils with a low phosphorus (P supply, sugar beet is known to intake more P than other species such as maize, wheat, or groundnut. We hypothesized that organic compounds exuded by sugar beet roots solubilize soil P and that this exudation is stimulated by P starvation. Results Root exudates were collected from plants grown in hydroponics under low- and high-P availability. Exudate components were separated by HPLC, ionized by electrospray, and detected by mass spectrometry in the range of mass-to-charge ratio (m/z from 100 to 1000. Eight mass spectrometric signals were enhanced at least 5-fold by low P availability at all harvest times. Among these signals, negative ions with an m/z of 137 and 147 were shown to originate from salicylic acid and citramalic acid. The ability of both compounds to mobilize soil P was demonstrated by incubation of pure substances with Oxisol soil fertilized with calcium phosphate. Conclusions Root exudates of sugar beet contain salicylic acid and citramalic acid, the latter of which has rarely been detected in plants so far. Both metabolites solubilize soil P and their exudation by roots is stimulated by P deficiency. These results provide the first assignment of a biological function to citramalic acid of plant origin.

  18. SIZ1 regulation of phosphate starvation-induced root architecture remodeling involves the control of auxin accumulation.

    Science.gov (United States)

    Miura, Kenji; Lee, Jiyoung; Gong, Qingqiu; Ma, Shisong; Jin, Jing Bo; Yoo, Chan Yul; Miura, Tomoko; Sato, Aiko; Bohnert, Hans J; Hasegawa, Paul M

    2011-02-01

    Phosphate (Pi) limitation causes plants to modulate the architecture of their root systems to facilitate the acquisition of Pi. Previously, we reported that the Arabidopsis (Arabidopsis thaliana) SUMO E3 ligase SIZ1 regulates root architecture remodeling in response to Pi limitation; namely, the siz1 mutations cause the inhibition of primary root (PR) elongation and the promotion of lateral root (LR) formation. Here, we present evidence that SIZ1 is involved in the negative regulation of auxin patterning to modulate root system architecture in response to Pi starvation. The siz1 mutations caused greater PR growth inhibition and LR development of seedlings in response to Pi limitation. Similar root phenotypes occurred if Pi-deficient wild-type seedlings were supplemented with auxin. N-1-Naphthylphthalamic acid, an inhibitor of auxin efflux activity, reduced the Pi starvation-induced LR root formation of siz1 seedlings to a level equivalent to that seen in the wild type. Monitoring of the auxin-responsive reporter DR5::uidA indicated that auxin accumulates in PR tips at early stages of the Pi starvation response. Subsequently, DR5::uidA expression was observed in the LR primordia, which was associated with LR elongation. The time-sequential patterning of DR5::uidA expression occurred earlier in the roots of siz1 as compared with the wild type. In addition, microarray analysis revealed that several other auxin-responsive genes, including genes involved in cell wall loosening and biosynthesis, were up-regulated in siz1 relative to wild-type seedlings in response to Pi starvation. Together, these results suggest that SIZ1 negatively regulates Pi starvation-induced root architecture remodeling through the control of auxin patterning.

  19. Stimulation of indoleacetic acid production in a Rhizobium isolate of Vigna mungo by root nodule phenolic acids.

    Science.gov (United States)

    Mandal, Santi M; Mandal, Santi; Mandal, Mahitosh; Das, Amit K; Das, Amit; Pati, Bikas R; Pati, Bikas; Ghosh, Ananta K; Ghosh, Ananta

    2009-04-01

    The influence of endogenous root nodules phenolic acids on indoleacetic acid (IAA) production by its symbiont (Rhizobium) was examined. The root nodules contain higher amount of IAA and phenolic acids than non-nodulated roots. Presence of IAA metabolizing enzymes, IAA oxidase, peroxidase, and polyphenol oxidase indicate the metabolism of IAA in the nodules and roots. Three most abundant endogenous root nodule phenolic acids (protocatechuic acid, 4-hydroxybenzaldehyde and p-coumaric acid) have been identified and their effects on IAA production by the symbiont have been studied in L-tryptophan supplemented yeast extract basal medium. Protocatechuic acid (1.5 microg ml(-1)) showed maximum stimulation (2.15-fold over control) of IAA production in rhizobial culture. These results indicate that the phenolic acids present in the nodule might serve as a stimulator for IAA production by the symbiont (Rhizobium).

  20. The Kidney and Acid-Base Regulation

    Science.gov (United States)

    Koeppen, Bruce M.

    2009-01-01

    Since the topic of the role of the kidneys in the regulation of acid base balance was last reviewed from a teaching perspective (Koeppen BM. Renal regulation of acid-base balance. Adv Physiol Educ 20: 132-141, 1998), our understanding of the specific membrane transporters involved in H+, HCO , and NH transport, and especially how these…

  1. The Kidney and Acid-Base Regulation

    Science.gov (United States)

    Koeppen, Bruce M.

    2009-01-01

    Since the topic of the role of the kidneys in the regulation of acid base balance was last reviewed from a teaching perspective (Koeppen BM. Renal regulation of acid-base balance. Adv Physiol Educ 20: 132-141, 1998), our understanding of the specific membrane transporters involved in H+, HCO , and NH transport, and especially how these…

  2. Metabolism and root exudation of organic acid anions under aluminium stress

    OpenAIRE

    Eduardo D Mariano; Jorge, Renato A; Keltjens, Willem G.; Menossi, Marcelo

    2005-01-01

    Numerous plant species can release organic acid anions (OA) from their roots in response to toxic aluminium (Al) ions present in the rooting medium. Hypothetically OA complex Al in the root apoplast and/or rhizosphere and thus avoid its interaction with root cellular components and its entry in the root symplast. Two temporal patterns of root OA exudation are observed. In pattern I, OA release is rapidly activated after the contact of the root with Al ions while in pattern II there is a lag p...

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

    Science.gov (United States)

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

    2012-02-15

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

  4. Dynamic change of organic acids secreted from wheat roots in Mn deficiency

    Institute of Scientific and Technical Information of China (English)

    Zheng FANG; Zhenfeng AN; Yingli LI

    2008-01-01

    Through solution culture experiment and liquid chromatogram technique, two wheat (Triticum aestivum L.) genotypes with different tolerances to Mn deficiency were used to study the dynamic change of organic acids secreted from wheat root in the conditions of no Mn, low Mn and normal Mn supply. Nine kinds of organic acids were measured in wheat root exudate. The results showed that there were significant differences of organic acids in root exudate between tolerant genotype and susceptible genotype under Mn-stressed conditions. Tolerant genotype 9023 secreted more organic acids from the plant roots than susceptible genotype CM28. The main organic acid exudate included tartaric acid, malic acid, acetic acid, maleic acid and fumaric acid. Of all these acids, the amounts of tartaric acid and malic acid in root exudate showed significant differences between the tolerant genotype and susceptible genotype under Mn-stressed conditions. The results also indicated that secreting organic acids into root rhizosphere was an active response to Mn deficiency for the tolerant genotype of wheat.

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

    Science.gov (United States)

    Moore, R.

    1990-01-01

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

  6. Asparagus root regulates cholesterol metabolism and improves antioxidant status in hypercholesteremic rats.

    Science.gov (United States)

    Visavadiya, Nishant P; Narasimhacharya, A V R L

    2009-06-01

    Hyperlipidemia/hypercholesteremia are major risk factors for atherosclerosis and cardiovascular diseases. Root of Asparagus racemosus (AR) is widely used in Ayurvedic system of medicine in India and is known for its steroidal saponin content. This study was designed to investigate the hypocholesteremic and antioxidant potential of AR root in both normo- and hypercholesteremic animals. Normal and hypercholesteremic male albino rats were administered with root powder of AR (5 and 10 g% dose levels) along with normal and hypercholesteremic diets, respectively, for a duration of 4 weeks. Plasma and hepatic lipid profiles, fecal sterol, bile acid excretion and hepatic antioxidant activity were assessed. Inclusion of AR root powder in diet, resulted in a dose-dependant reduction in plasma and hepatic lipid profiles, increased fecal excretion of cholesterol, neutral sterol and bile acid along with increases in hepatic HMG-CoA reductase activity and bile acid content in hypercholesteremic rats. Further, AR root also improved the hepatic antioxidant status (catalase, SOD and ascorbic acid levels). No significant changes in lipid and antioxidant profiles occurred in the normocholesteremic rats administered with AR root powder. AR root appeared to be useful as a dietary supplement that offers a protection against hyperlipidemia/hypercholesteremia in hypercholesteremic animals. The results of the present study indicate that the potent therapeutic phyto-components present in AR root i.e. phytosterols, saponins, polyphenols, flavonoids and ascorbic acid, could be responsible for increased bile acid production, elimination of excess cholesterol and elevation of hepatic antioxidant status in hypercholesteremic conditions.

  7. [Effect of wheat and faba bean intercropping on root exudation of low molecular weight organic acids].

    Science.gov (United States)

    Xiao, Jing-Xiu; Zheng, Yi; Tang, Li

    2014-06-01

    Pot experiment of wheat and faba bean intercropping was conducted and exudates from wheat and faba bean roots were collected at different growth stages. Low molecular weight organic acids (OA) in root exudates were examined by HPLC. The results showed that wheat and faba bean intercropping significantly increased the total amounts of OA exuded by roots. At tillering (57 d), booting (120 d) and filling stages (142 d), intercropping increased the total amounts of OA in wheat root exudates by 155%, 35.6% and 92.6% respectively, in comparison with that of monoculture wheat (MW). At branching (57 d) and filling stages (142 d), intercropping increased the total amounts of OA in faba bean root exudates by 87.4% and 38.7%, respectively, in comparison with that of monoculture faba bean (MF). Wheat and faba bean intercropping changed the types of OA exuded by roots. At tillering stage, lactic acid was identified in root exudates of intercropping wheat (IW), but not in that of MW. At jointing stage (98 d), citric acid was identified in root exudates of IW, but not in that of MW, and acetic acid was vice versa. At branching stage, acetic acid was identified in root exudates of intercropping faba bean (IF), but not in that of MF, and lactic acid was vice versa. At filling stage, lactic acid was identified in root exudates of IF, but not in that of MF. Wheat and faba bean intercropping increased the OA exudation rate of wheat. At booting stage, the exudation rates of citric and fumaric acid from IW were 179 and 184-times as that of from MW, respectively. At filling stage, the exudation rate of lactic acid from IW was 2.53-times as that from MW. In conclusion, wheat and faba bean intercropping increased the rate and total amount, and changed the types of OA exuded by roots.

  8. Effect of QMix, peracetic acid and ethylenediaminetetraacetic acid on calcium loss and microhardness of root dentine

    Directory of Open Access Journals (Sweden)

    Sonali Taneja

    2014-01-01

    Full Text Available Objectives: The objective of this in vitro study was to assess the effect of different chelating agents on the calcium loss and its subsequent effect on the microhardness of the root dentin. Materials and Methods: Ten single rooted lower premolars were selected. The teeth were decoronated and thick transverse sections of 2 mm were obtained from the coronal third of the root. Each section was then divided into four quarters, each part constituting a sample specimen from the same tooth for each group. The treatment groups were: Group 1 (Control: 5% Sodium hypochlorite (NaOCl for 5 min + distilled water for 5 min; Group 2: 5% NaOCl for 5 min + 17% ethylenediaminetetraacetic acid (EDTA for 5 min; Group 3: 5% NaOCl for 5 min + 2.25% Peracetic acid (PAA for 5 min and Group 4: 5% NaOCl for 5 min + QMix for 5 min respectively. The calcium loss of the samples was evaluated using the Atomic Absorption Spectrophotometer followed by determination of their microhardness using Vickers Hardness Tester. Data was analyzed using one-way ANOVA, Post hoc Tukey test and Pearson correlation. Results: The maximum calcium loss and minimum microhardness was observed in Group 3 followed by Group 2, Group 4 and Group 1. There was a statistically significant difference between all the groups except between Groups 2 and 4. Conclusions: Irrigation with NaOCl + 2.25% PAA caused the maximum calcium loss from root dentin and reduced microhardness. A negative correlation existed between the calcium loss and reduction in the microhardness of root dentin.

  9. The Solanum lycopersicum auxin response factor SlARF2 participates in regulating lateral root formation and flower organ senescence.

    Science.gov (United States)

    Ren, Zhenxin; Liu, Ruiyuan; Gu, Wenting; Dong, Xicun

    2017-03-01

    ARF2 as apleiotropic developmental regulator has been reported in Arabidopsis thaliana and tomato (Solanum lycopersicum). The present study showed SlARF2 transcripts in all tomato plant tissues but with higher accumulation in flowers. During bud-anthesis stages, SlARF2 transcripts showed a dynamic expression pattern in sepal, stamen, ovary and petal. Hormone treatment analysis suggested that SlARF2 transcript accumulation was positively regulated by auxin and gibberellic acid, and negatively regulated by ethylene in tomato seedlings. Phenotypes and molecular analyses of SlARF2-upregulated transgenic tomato indicated that SlARF2 regulated tomato lateral root formation and flower organ senescence may be partially mediated by regulating the gene expression of auxin and ethylene response factors. The data enlarges the functional characterization of SlARF2 in tomato, and broadens our understanding of auxin signaling in regulating plant growth and development. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  10. [Effects of cinnamic acid and vanillin on grafted eggplant root growth and physiological characteristics].

    Science.gov (United States)

    Chen, Shao-Li; Zhou, Bao-Li; Lin, Shan-Shan; Li, Xia; Ye, Xue-Ling

    2010-06-01

    Choosing Solanum torvum as rootstock and cultivated Xi'anlü eggplant as scion, a pot culture experiment was conducted to study the effects of autotoxic substances (cinnamic acid and vanillin) on the root growth, antioxidase activity, and osmoregulation substances content of grafted eggplant, own-rooted eggplant, and rootstock eggplant. Cinnamic acid and vanillin had allelopathic effects on the root system of test eggplants, with low concentration promoting and higher concentration inhibiting the root growth and physiological metabolism. For own-rooted eggplant, the critical concentration of cinnamic acid and vanillin for promotion or inhibition was 0.1 mmol x kg(-1) and 0.5 mmol x kg(-1), respectively; whereas for grafted and rootstock eggplants, it was 0.5 mmol x kg(-1) and 1 mmol x kg(-1), respectively. The root resistance to autotoxic substances was in the order of root-stock eggplant > grafted eggplant > own-rooted eggplant. Higher concentration cinamic acid (0.5-4 mmol x kg(-1)) and vanillin (1-4 mmol x kg(-1)) enhanced the SOD enzyme activity and the proline and soluble sugar contents of grafted eggplant root by 8.50%-24.50%; 9.39%-27.64%, and 12.77%-81.81%, respectively, compared with own-rooted eggplant. The soluble protein content, fresh mass, dry mass, and root activity of grafted eggplant roots were significantly higher than those of own-rooted eggplant, suggesting that grafted eggplant had a strong resistance of rootstocks to autotoxic substances, which alleviated the negative effect of autotoxic substances on root growth.

  11. Modulation of Root Signals in Relation to Stomatal Sensitivity to Root-sourced Abscisic Acid in Drought-affected Plants

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Stomatal sensitivity to root signals induced by soil drying may vary between environments and plant species. This is likely central role in root to shoot signaling. pH and hydraulic signals may interact with ABA signals and thus, jointly regulate stomatal responses to changed soil water status. pH itself can be modified by several factors, among which the chemical compositions In the xylem stream and the live cells surrounding the vessels play crucial roles. In addition to the xylem pH,more attention should be paid to the direct modulation of leaf apoplastic pH, because many chemical compositions might strongly modify the leaf apoplastlc pH while having no significant effect on the xylem pH. The direct modulation of the ABA signal intensity may be more important for the regulation of stomatal responses to soil drying than the ABA signal per se.The ABA signal is also regulated by the ABA catabolism and the supply of precursors to the roots If a sustained root to shoot communication of soil drying operates at the whole plant level. More importantly, ABA catabolism could play crucial roles In the determination of the fate of the ABA signal and thereby control the stomatal behavior of the root-sourced ABA signal.

  12. Bile acid biosynthesis and its regulation

    Directory of Open Access Journals (Sweden)

    Areta Hebanowska

    2010-10-01

    Full Text Available Bile acid biosynthesis is the main pathway of cholesterol catabolism. Bile acids are more soluble than cholesterol so are easier to excrete. As amphipathic molecules they participate in lipid digestion and absorption in the intestine and they help to excrete free cholesterol with bile. They are also ligands for nuclear receptors regulating the expression of genes involved in cholesterol metabolism. Interconversion of cholesterol into bile acids is an important point of its homeostasis. Seventeen enzymes are engaged in this process and many of them are cytochromes P450. Bile acid synthesis initiation may proceed with the “classical” pathway (starting with cholesterol hydroxylation at the C7α position or the “alternative” pathway (starting with cholesterol hydroxylation at the C27 position. Two additional pathways are possible, though their quantitative significance is small (initiated with cholesterol hydroxylations of C24 and C25 positions. Oxysterols produced are not only intermediates of bile acid biosynthesis but also important regulators of metabolism. Bile acid biosynthesis takes place in the liver, but some enzymes are also present in other organs, where they participate in regulation of cholesterol metabolism. Those enzymes are potential targets for new drugs against cholesterol metabolism disturbances. This article is a brief description of the bile acid biosynthesis pathway and participating enzymes.

  13. Effect of Indoleacetic acid (IAA) on the Negative Phototropism of Rice Root

    Institute of Scientific and Technical Information of China (English)

    MoYi-wei; WANGZhong; QIANShan-qin; GuYun-jie

    2004-01-01

    To explore the effects of IAA on negative phototropism of rice (Oryza sativa L) root, agar block containing IAA was unilaterally applied on root tip to examine the phototropic response of root to exogenous IAA, and microstructure of the bending part was observed with an optical microscope. The growth of seminal roots could be regulated by exogenous IAA as well as light,as a result the root bent towards the site treated, causing asymmetric growth of the root cells at the elongation zone and consequently bending growth. IAA concentration in the shaded side of adventitious root increased much greater at 1.5 h after the start of irradiation. The unequal lateral IAA distribution can be concluded to be the main cause for negative phototropism of rice root.

  14. [Role of NO signal in ABA-induced phenolic acids accumulation in Salvia miltiorrhiza hairy roots].

    Science.gov (United States)

    Shen, Lihong; Ren, Jiahui; Jin, Wenfang; Wang, Ruijie; Ni, Chunhong; Tong, Mengjiao; Liang, Zongsuo; Yang, Dongfeng

    2016-02-01

    To investigate roles of nitric oxide (NO) signal in accumulations of phenolic acids in abscisic.acid (ABA)-induced Salvia miltiorrhiza hairy roots, S. miltiorrhiza hairy roots were treated with different concentrations of sodium nitroprusside (SNP)-an exogenous NO donor, for 6 days, and contents of phenolic acids in the hairy roots are determined. Then with treatment of ABA and NO scavenger (2-(4-carboxy-2-phenyl)-4,4,5,5-tetramethylimidazoline-1- oxyl-3-oxide, c-PTIO) or NO synthase inhibitor (NG-nitro-L-arginine methyl ester, L-NAME), contents of phenolic acids and expression levels of three key genes involved in phenolic acids biosynthesis were detected. Phenolic acids production in S. miltiorrhiza hairy roots was most significantly improved by 100 µmoL/L SNP. Contents of RA and salvianolic acid B increased by 3 and 4 folds. ABA significantly improved transcript levels of PAL (phenylalanine ammonia lyase), TAT (tyrosine aminotransferase) and RAS (rosmarinic acid synthase), and increased phenolic acids accumulations. However, with treatments of ABA+c-PTIO or ABA+L-NAME, accumulations of phenolic acids and expression levels of the three key genes were significantly inhibited. Both NO and ABA can increase accumulations of phenolic acids in S. miltiorrhiza hairy roots. NO signal probably mediates the ABA-induced phenolic acids production.

  15. UMAMIT14 is an amino acid exporter involved in phloem unloading in Arabidopsis roots.

    Science.gov (United States)

    Besnard, Julien; Pratelli, Réjane; Zhao, Chengsong; Sonawala, Unnati; Collakova, Eva; Pilot, Guillaume; Okumoto, Sakiko

    2016-12-01

    Amino acids are the main form of nitrogen transported between the plant organs. Transport of amino acids across membranes is mediated by specialized proteins: importers, exporters, and facilitators. Unlike amino acid importers, amino acid exporters have not been thoroughly studied, partly due to a lack of high-throughput techniques enabling their isolation. Usually Multiple Acids Move In and out Transporters 14 (UMAMIT14) from Arabidopsis shares sequence similarity to the amino acid facilitator Silique Are Red1 (UMAMIT18), and has been shown to be involved in amino acid transfer to the seeds. We show here that UMAMIT14 is also expressed in root pericycle and phloem cells and mediates export of a broad range of amino acids in yeast. Loss-of-function of UMAMIT14 leads to a reduced shoot-to-root and root-to-medium transfer of amino acids originating from the leaves. These fluxes were further reduced in an umamti14 umamit18 double loss-of-function mutant. This study suggests that UMAMIT14 is involved in phloem unloading of amino acids in roots, and that UMAMIT14 and UMAMIT18 are involved in the radial transport of amino acids in roots, which is essential for maintaining amino acid secretion to the soil.

  16. Fatty Acid Desaturases, Polyunsaturated Fatty Acid Regulation, and Biotechnological Advances.

    Science.gov (United States)

    Lee, Je Min; Lee, Hyungjae; Kang, SeokBeom; Park, Woo Jung

    2016-01-04

    Polyunsaturated fatty acids (PUFAs) are considered to be critical nutrients to regulate human health and development, and numerous fatty acid desaturases play key roles in synthesizing PUFAs. Given the lack of delta-12 and -15 desaturases and the low levels of conversion to PUFAs, humans must consume some omega-3 and omega-6 fatty acids in their diet. Many studies on fatty acid desaturases as well as PUFAs have shown that fatty acid desaturase genes are closely related to different human physiological conditions. Since the first front-end desaturases from cyanobacteria were cloned, numerous desaturase genes have been identified and animals and plants have been genetically engineered to produce PUFAs such as eicosapentaenoic acid and docosahexaenoic acid. Recently, a biotechnological approach has been used to develop clinical treatments for human physiological conditions, including cancers and neurogenetic disorders. Thus, understanding the functions and regulation of PUFAs associated with human health and development by using biotechnology may facilitate the engineering of more advanced PUFA production and provide new insights into the complexity of fatty acid metabolism.

  17. Fatty Acid Desaturases, Polyunsaturated Fatty Acid Regulation, and Biotechnological Advances

    Directory of Open Access Journals (Sweden)

    Je Min Lee

    2016-01-01

    Full Text Available Polyunsaturated fatty acids (PUFAs are considered to be critical nutrients to regulate human health and development, and numerous fatty acid desaturases play key roles in synthesizing PUFAs. Given the lack of delta-12 and -15 desaturases and the low levels of conversion to PUFAs, humans must consume some omega-3 and omega-6 fatty acids in their diet. Many studies on fatty acid desaturases as well as PUFAs have shown that fatty acid desaturase genes are closely related to different human physiological conditions. Since the first front-end desaturases from cyanobacteria were cloned, numerous desaturase genes have been identified and animals and plants have been genetically engineered to produce PUFAs such as eicosapentaenoic acid and docosahexaenoic acid. Recently, a biotechnological approach has been used to develop clinical treatments for human physiological conditions, including cancers and neurogenetic disorders. Thus, understanding the functions and regulation of PUFAs associated with human health and development by using biotechnology may facilitate the engineering of more advanced PUFA production and provide new insights into the complexity of fatty acid metabolism.

  18. ABNORMAL INFLORESCENCE MERISTEM1 Functions in Salicylic Acid Biosynthesis to Maintain Proper Reactive Oxygen Species Levels for Root Meristem Activity in Rice.

    Science.gov (United States)

    Xu, Lei; Zhao, Hongyu; Ruan, Wenyuan; Deng, Minjuan; Wang, Fang; Peng, Jinrong; Luo, Jie; Chen, Zhixiang; Yi, Keke

    2017-03-01

    Root meristem activity determines root growth and root architecture and consequently affects water and nutrient uptake in plants. However, our knowledge about the regulation of root meristem activity in crop plants is very limited. Here, we report the isolation and characterization of a short root mutant in rice (Oryza sativa) with reduced root meristem activity. This root growth defect is caused by a mutation in ABNORMAL INFLORESCENCE MERISTEM1 (AIM1), which encodes a 3-hydroxyacyl-CoA dehydrogenase, an enzyme involved in β-oxidation. The reduced root meristem activity of aim1 results from reduced salicylic acid (SA) levels and can be rescued by SA application. Furthermore, reduced SA levels are associated with reduced levels of reactive oxygen species (ROS) in aim1, likely due to increased expression of redox and ROS-scavenging-related genes, whose increased expression is (at least in part) caused by reduced expression of the SA-inducible transcriptional repressors WRKY62 and WRKY76. Like SA, ROS application substantially increased root length and root meristem activity in aim1 These results suggest that AIM1 is required for root growth in rice due to its critical role in SA biosynthesis: SA maintains root meristem activity through promoting ROS accumulation by inducing the activity of WRKY transcriptional repressors, which repress the expression of redox and ROS-scavenging genes. © 2017 American Society of Plant Biologists. All rights reserved.

  19. SCFTIR1/AFB-auxin signalling regulates PIN vacuolar trafficking and auxin fluxes during root gravitropism

    NARCIS (Netherlands)

    Baster, P.; Robert, S.; Kleine-Vehn, J.; Vanneste, S.; Kania, U.; Grunewald, W.; Rybel, de B.P.M.; Beeckman, T.; Friml, J.

    2013-01-01

    The distribution of the phytohormone auxin regulates many aspects of plant development including growth response to gravity. Gravitropic root curvature involves coordinated and asymmetric cell elongation between the lower and upper side of the root, mediated by differential cellular auxin levels.

  20. SCFTIR1/AFB-auxin signalling regulates PIN vacuolar trafficking and auxin fluxes during root gravitropism

    NARCIS (Netherlands)

    Baster, P.; Robert, S.; Kleine-Vehn, J.; Vanneste, S.; Kania, U.; Grunewald, W.; Rybel, de B.P.M.; Beeckman, T.; Friml, J.

    2013-01-01

    The distribution of the phytohormone auxin regulates many aspects of plant development including growth response to gravity. Gravitropic root curvature involves coordinated and asymmetric cell elongation between the lower and upper side of the root, mediated by differential cellular auxin levels. Th

  1. [Correlation of Allelopathy of Rehmannia glutinosa Root Exudates and Their Phenolic Acids Contents].

    Science.gov (United States)

    Zhang, Bao; Li, Xuan-zhen; Feng, Fa-jie; Gu, Li; Zhang, Jun-yi; Zhang, Liu-ji; Zhang, Zhong-yi

    2015-04-01

    To study the allelopathic potential of Rehmannia glutinosa root exudates in different growth stages and dynamic change of phenolic acids contents, in order to reveal the correlation between phenolic acids and allelbpathy effect of Rehmannia glutinosa. Root exudates of Rehmannia glutinosa in different growth stages were obtained by a new instrument which was used to collect the root exudates of xerophytes. After that, bioassay was applied to estimate allelopathy effect of the root exudates. HPLC was used to determine the contents of five phenolic acids (coumaric acid, 4-hydroxybenzoic acid, vanillic acid, syringic acid and ferulic acid) which were reported to relate to allelopathy effect. Correlation of bioassay data and HPLC data were also analyzed. The germination rate of radish after soaking by root exudates of different growth stages of Rehmannia glutinosa was 97. 89%, 92. 38%, 89. 52%, 85. 71%, 85. 71%, 84. 76% and 83. 81%, respectively, which indicated a decline trend. And significant differences were shown from previous enlargement stage compared with the contrast. The bud length after soaking by root exudates was 5. 68, 5. 76, 5. 91, 5. 65, 5. 41, 5. 28 and 5. 11 cm, separately, which increased slightly before decreasing gradually. Previous enlargement stage was also the initial period when significant differences were shown. Five phenolic acids were detected in root exudates by HPLC, while the change of their contents and the allelopathy effect of root exudates did not perform a similar trend. Correlation analysis indicated the five phenolic acids did not have significant relevance (r = - 0. 666 - 0. 590) with germination rate and bud length of radish except the negative correlation (r = -0. 833, P allelopathy effect of Rehmannia glutinosa is performed from previous enlargement stage and enhanced with its growth. Syringic acid is a probable dominant allelochemical of Rehmannia glutinosa.

  2. An auxin-responsive endogenous peptide regulates root development in Arabidopsis.

    Science.gov (United States)

    Yang, Fengxi; Song, Yu; Yang, Hao; Liu, Zhibin; Zhu, Genfa; Yang, Yi

    2014-07-01

    Auxin plays critical roles in root formation and development. The components involved in this process, however, are not well understood. Here, we newly identified a peptide encoding gene, auxin-responsive endogenous polypeptide 1 (AREP1), which is induced by auxin, and mediates root development in Arabidopsis. Expression of AREP1 was specific to the cotyledon and to root and shoot meristem tissues. Amounts of AREP1 transcripts and AREP1-green fluorescent protein fusion proteins were elevated in response to indoleacetic acid treatment. Suppression of AREP1 through RNAi silencing resulted in reduction of primary root length, increase of lateral root number, and expansion of adventitious roots, compared to the observations in wild-type plants in the presence of auxin. By contrast, transgenic plants overexpressing AREP1 showed enhanced growth of the primary root under auxin treatment. Additionally, root morphology, including lateral root number and adventitious roots, differed greatly between transgenic and wild-type plants. Further analysis indicated that the expression of auxin-responsive genes, such as IAA3, IAA7, IAA17, GH3.2, GH3.3, and SAUR-AC1, was significantly higher in AREP1 RNAi plants, and was slightly lower in AREP1 overexpressing plants than in wild-type plants. These results suggest that the novel endogenous peptide AREP1 plays an important role in the process of auxin-mediated root development.

  3. Shoot-derived cytokinins systemically regulate root nodulation.

    Science.gov (United States)

    Sasaki, Takema; Suzaki, Takuya; Soyano, Takashi; Kojima, Mikiko; Sakakibara, Hitoshi; Kawaguchi, Masayoshi

    2014-09-19

    Legumes establish symbiotic associations with nitrogen-fixing bacteria (rhizobia) in root nodules to obtain nitrogen. Legumes control nodule number through long-distance communication between roots and shoots, maintaining the proper symbiotic balance. Rhizobial infection triggers the production of mobile CLE-RS1/2 peptides in Lotus japonicus roots; the perception of the signal by receptor kinase HAR1 in shoots presumably induces the production of an unidentified shoot-derived inhibitor (SDI) that translocates to roots and blocks further nodule development. Here we show that, CLE-RS1/2-HAR1 signalling activates the production of shoot-derived cytokinins, which have an SDI-like capacity to systemically suppress nodulation. In addition, we show that LjIPT3 is involved in nodulation-related cytokinin production in shoots. The expression of LjIPT3 is activated in an HAR1-dependent manner. We further demonstrate shoot-to-root long-distance transport of cytokinin in L. japonicus seedlings. These findings add essential components to our understanding of how legumes control nodulation to balance nutritional requirements and energy status.

  4. Systemic regulation of soybean nodulation by acidic growth conditions.

    Science.gov (United States)

    Lin, Meng-Han; Gresshoff, Peter M; Ferguson, Brett J

    2012-12-01

    Mechanisms inhibiting legume nodulation by low soil pH, although highly prevalent and economically significant, are poorly understood. We addressed this in soybean (Glycine max) using a combination of physiological and genetic approaches. Split-root and grafting studies using an autoregulation-of-nodulation-deficient mutant line, altered in the autoregulation-of-nodulation receptor kinase GmNARK, determined that a systemic, shoot-controlled, and GmNARK-dependent mechanism was critical for facilitating the inhibitory effect. Acid inhibition was independent of aluminum ion concentration and occurred early in nodule development, between 12 and 96 h post inoculation with Bradyrhizobium japonicum. Biological effects were confirmed by measuring transcript numbers of known early nodulation genes. Transcripts decreased on both sides of split-root systems, where only one side was subjected to low-pH conditions. Our findings enhance the present understanding of the innate mechanisms regulating legume nodulation control under acidic conditions, which could benefit future attempts in agriculture to improve nodule development and biological nitrogen fixation in acid-stressed soils.

  5. Balancing Water Uptake and Loss through the Coordinated Regulation of Stomatal and Root Development.

    Directory of Open Access Journals (Sweden)

    Christopher Hepworth

    Full Text Available Root development is influenced by nutrient and water availabilities. Plants are able to adjust many attributes of their root in response to environmental signals including the size and shape of the primary root, lateral roots and root hairs. Here we investigated the response of roots to changes in the levels of leaf transpiration associated with altered stomatal frequency. We found that plants with high stomatal density and conductance produce a larger rooting area and as a result have enhanced phosphate uptake capacity whereas plants with low stomatal conductance produce a smaller root. Manipulating the growth environment of plants indicated that enhanced root growth is most likely a result of an increased demand for water rather than phosphate. Plants manipulated to have an increase or reduction in root hair growth show a reduction or increase respectively, in stomatal conductance and density. Our results demonstrate that plants can balance their water uptake and loss through coordinated regulation of both stomatal and root development.

  6. Establishment of adventitious root cultures of Echinacea purpurea for the production of caffeic acid derivatives.

    Science.gov (United States)

    Paek, Kee-Yoeup; Murthy, Hosakatte Niranjana; Hahn, Eun-Joo

    2009-01-01

    Echinacace purpurea (purple cone flower) is an important medicinal plant, and widely used for phytochemical purposes. The roots are traditionally used in herbal medicines and dietary supplements as an immunostimulant in treating inflammatory and viral diseases. Extensive research work has been carried out on both the induction of adventitious roots from E. purpurea as well as established small-scale (shake flask) to large-scale (bioreactor) cultures for the production of adventitious root biomass and caffeic acid derivatives. This chapter describes the methodologies of induction of adventitious roots from explants of E. purpurea, propagation of adventitious roots in suspension cultures, estimation of total phenolics, flavonoids, and antioxidant activities. The detailed methodology for high-performance liquid chromatographic analysis of caffeic acid derivatives present in the adventitious roots is also discussed.

  7. In Vitro Growth and Rooting of Mangosteen (Garcinia mangostana L. on Medium with Different Concentrations of Plant Growth Regulator

    Directory of Open Access Journals (Sweden)

    FAUZIYAH HARAHAP

    2014-12-01

    Full Text Available Propagation of mangosteen is challenging for many reasons, including limited seed set, slow rate of seedling growth, and difficulty with root formations. The objective of this research was to find the best combination of medium and plant growth regulator for in vitro growth and rooting of mangosteeen seed. Various types of explant (a whole seed; seed divided into 2, 3, and 4 cross sections; seed divided into 2, 3, and 4 longitudinal sections were treated with five concentrations of benzyl amino purine (BAP; 0, 2.5, 5, 7.5, 10 mg/L for shoot induction in ½ Nitrogen (N Murashige and Skoog (MS medium. The shoots were rooted on MS and woody plant medium (WPM media with several combinations of indole butyric acid (IBA and naphtalene acetic acid (NAA. Treatments for root induction were applied as follows: (i low dose, given during induction of rooting, (ii soaking the base of the shoots in medium treated with a high dose of auxin for 5 days, and then growing the shoots in MS ½ N with 1 mg/L NAA + 1 mg/L BAP medium. Our result show that BAP positively affected mangosteen bud growth. The best medium for mangosteen shoot regeneration was found to be MS ½ N + 5 mg/L BAP. This medium induced the highest number of shoots from the seed explant cut into four cross sections. We found the best medium to induce in vitro rooting of mangosteen shoot was MS ½ N + 3 mg/L indole butiric acid (IBA + 4 mg/L NAA medium. Some treatment negatively affected growth. Soaking the mangosteen shoot base in a medium with an overly high dose of auxin seemed to disrupt and inhibit growth of the mangosteen shoot.

  8. Spatiotemporal aspect of cytokinin-auxin interaction in hormonal regulation of the root meristem

    Science.gov (United States)

    Kuderová, Alena

    2009-01-01

    Hormonal regulation of root development is a long known phenomenon. In the past decades, the molecular mechanisms of individual hormonal pathways and their impact on root development have been studied. Recent genetic and molecular studies suggest importance of interactions of the individual hormonal pathways and their components. In our paper1 we show impact of endogenous cytokinin on the root architecture and its interaction with auxin in Arabidopsis thaliana. In this addendum we discuss our results in the light of significant recent papers that deal with cytokinin-auxin interactions and we point out spatiotemporal specificity of these interactions in the root development. PMID:19649199

  9. Complex Regulation of Prolyl-4-Hydroxylases Impacts Root Hair Expansion

    DEFF Research Database (Denmark)

    Velasquez, Silvia M; Ricardi, Martiniano M; Poulsen, Christian Peter

    2015-01-01

    Root hairs are single cells that develop by tip growth, a process shared with pollen tubes, axons, and fungal hyphae. However, structural plant cell walls impose constraints to accomplish tip growth. In addition to polysaccharides, plant cell walls are composed of hydroxyproline-rich glycoprotein...

  10. Shoot-derived cytokinins systemically regulate root nodulation

    National Research Council Canada - National Science Library

    Sasaki, Takema; Suzaki, Takuya; Soyano, Takashi; Kojima, Mikiko; Sakakibara, Hitoshi; Kawaguchi, Masayoshi

    2014-01-01

    ...) that translocates to roots and blocks further nodule development. Here we show that, CLE-RS1/2-HAR1 signalling activates the production of shoot-derived cytokinins, which have an SDI-like capacity to systemically suppress nodulation...

  11. An auxin-responsive endogenous peptide regulates root development in Arabidopsis

    Institute of Scientific and Technical Information of China (English)

    Fengxi Yang; Yu Song; Hao Yang; Zhibin Liu; Genfa Zhu; Yi Yang

    2014-01-01

    Auxin plays critical roles in root formation and development. The components involved in this process, however, are not well understood. Here, we newly identified a peptide encoding gene, auxin-responsive endogenous polypeptide 1 (AREP1), which is induced by auxin, and mediates root development in Arabidopsis. Expression of AREP1 was specific to the cotyledon and to root and shoot meristem tissues. Amounts of AREP1 transcripts and AREP1-green fluorescent protein fusion proteins were elevated in response to indoleacetic acid treatment. Suppression of AREP1 through RNAi silencing resulted in reduction of primary root length, increase of lateral root number, and expansion of adventitious roots, compared to the observations in wild-type plants in the presence of auxin. By contrast, transgenic plants overexpressing AREP1 showed enhanced growth of the primary root under auxin treatment. Additionally, rootmorphology, including lateral root number and adventitious roots, differed greatly between transgenic and wildtype plants. Further analysis indicated that the expression of auxin-responsive genes, such as IAA3, IAA7, IAA17, GH3.2, GH3.3, and SAUR-AC1, was significantly higher in AREP1 RNAi plants, and was slightly lower in AREP1 overexpressing plants than in wildtype plants. These results suggest that the novel endogenous peptide AREP1 plays an important role in the process of auxinmediated root development.

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

    Science.gov (United States)

    Moore, R.; Dickey, K.

    1985-01-01

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

  13. Asparagus Root Regulates Cholesterol Metabolism and Improves Antioxidant Status in Hypercholesteremic Rats

    Directory of Open Access Journals (Sweden)

    Nishant P. Visavadiya

    2009-01-01

    Full Text Available Hyperlipidemia/hypercholesteremia are major risk factors for atherosclerosis and cardiovascular diseases. Root of Asparagus racemosus (AR is widely used in Ayurvedic system of medicine in India and is known for its steroidal saponin content. This study was designed to investigate the hypocholesteremic and antioxidant potential of AR root in both normo- and hypercholesteremic animals. Normal and hypercholesteremic male albino rats were administered with root powder of AR (5 and 10 g% dose levels along with normal and hypercholesteremic diets, respectively, for a duration of 4 weeks. Plasma and hepatic lipid profiles, fecal sterol, bile acid excretion and hepatic antioxidant activity were assessed. Inclusion of AR root powder in diet, resulted in a dose-dependant reduction in plasma and hepatic lipid profiles, increased fecal excretion of cholesterol, neutral sterol and bile acid along with increases in hepatic HMG-CoA reductase activity and bile acid content in hypercholesteremic rats. Further, AR root also improved the hepatic antioxidant status (catalase, SOD and ascorbic acid levels. No significant changes in lipid and antioxidant profiles occurred in the normocholesteremic rats administered with AR root powder. AR root appeared to be useful as a dietary supplement that offers a protection against hyperlipidemia/hypercholesteremia in hypercholesteremic animals. The results of the present study indicate that the potent therapeutic phyto-components present in AR root i.e. phytosterols, saponins, polyphenols, flavonoids and ascorbic acid, could be responsible for increased bile acid production, elimination of excess cholesterol and elevation of hepatic antioxidant status in hypercholesteremic conditions.

  14. Enhanced lignin monomer production caused by cinnamic Acid and its hydroxylated derivatives inhibits soybean root growth.

    Directory of Open Access Journals (Sweden)

    Rogério Barbosa Lima

    Full Text Available Cinnamic acid and its hydroxylated derivatives (p-coumaric, caffeic, ferulic and sinapic acids are known allelochemicals that affect the seed germination and root growth of many plant species. Recent studies have indicated that the reduction of root growth by these allelochemicals is associated with premature cell wall lignification. We hypothesized that an influx of these compounds into the phenylpropanoid pathway increases the lignin monomer content and reduces the root growth. To confirm this hypothesis, we evaluated the effects of cinnamic, p-coumaric, caffeic, ferulic and sinapic acids on soybean root growth, lignin and the composition of p-hydroxyphenyl (H, guaiacyl (G and syringyl (S monomers. To this end, three-day-old seedlings were cultivated in nutrient solution with or without allelochemical (or selective enzymatic inhibitors of the phenylpropanoid pathway in a growth chamber for 24 h. In general, the results showed that 1 cinnamic, p-coumaric, caffeic and ferulic acids reduced root growth and increased lignin content; 2 cinnamic and p-coumaric acids increased p-hydroxyphenyl (H monomer content, whereas p-coumaric, caffeic and ferulic acids increased guaiacyl (G content, and sinapic acid increased sinapyl (S content; 3 when applied in conjunction with piperonylic acid (PIP, an inhibitor of the cinnamate 4-hydroxylase, C4H, cinnamic acid reduced H, G and S contents; and 4 when applied in conjunction with 3,4-(methylenedioxycinnamic acid (MDCA, an inhibitor of the 4-coumarate:CoA ligase, 4CL, p-coumaric acid reduced H, G and S contents, whereas caffeic, ferulic and sinapic acids reduced G and S contents. These results confirm our hypothesis that exogenously applied allelochemicals are channeled into the phenylpropanoid pathway causing excessive production of lignin and its main monomers. By consequence, an enhanced stiffening of the cell wall restricts soybean root growth.

  15. Determining Rooting Ability of Ennobled Blueberry Wood Pieces (Vaccinium corymbosum L. with Presence of Growth Regulators IBA and NAA

    Directory of Open Access Journals (Sweden)

    SABRI BRAHA

    2015-12-01

    Full Text Available Ennobled blueberry (V. Corymbosum L. has many specific requirements for optimal growth, therefore, the increase of cultivated areas is limited. It requires acidic soils (pH 4,3-4,8, well drained, with full aeration and a constant moderate amount of moisture. The successful technique of asexual propagation will be necessary for rapid clonal propagation of selected cultivars. The objective of this experiment was to identify an efficient way to improve rooting with the help of growth regulators in the ‘Bluecrop’ cultivar using well-lignified one-year old wood pieces, collected at the end of winter, end of March prior to bud swelling. Treatments with various concentrations (1500, 3000, 4500 mg/l, show that treatment with IBA at 3000 mg/l has the highest rooting percentage in comparison to NAA. Whilst the torf-perlite substrate (at a 2:1 ratio, has produced a higher rooting percentage compared to the torf-only substrate, and the crucial factor for successful rooting is the time of collecting wood pieces. Treatment results have promoted higher rooting of wooden pieces compared to the control (untreated wooden pieces. The most efficient promotor in all concentrations was IBA.

  16. Identification of genes regulated by histone acetylation during root development in Populus trichocarpa.

    Science.gov (United States)

    Ma, Xujun; Zhang, Chao; Zhang, Bing; Yang, Chuanping; Li, Shujuan

    2016-02-04

    Histone deacetylases (HDACs) are key enzymes catalyzing the removal of acetyl groups from histones. HDACs act in concert with histone acetyltransferases (HATs) to regulate histone acetylation status, which modifies chromatin structure, affecting gene transcription and thus regulating multiple biological processes such as plant growth and development. Over a decade, certain HDACs in herbaceous plants have been deeply studied. However, functions of HDACs in woody plants are not well understood. Histone deacetylase specific inhibitor trichostatin A (TSA) was used to investigate the role of HDACs in organogenesis of roots and root development in Populus trochocarpa. The adventitious roots were regenerated and grown on medium supplemented with 0, 1, and 2.5 μM TSA. TSA treatment delayed root regeneration and inhibited primary root growth. To examine the genes modified by TSA in the regenerated roots, tag-based digital gene expression (DGE) analysis was performed using Illumina HiSeqTM 2000. Approximately 4.5 million total clean tags were mapped per library. The distinct clean tags for the three libraries corresponding to 0, 1 and 2.5 μM TSA treatment were 166167, 143103 and 153507, from which 38.45%, 31.84% and 38.88% were mapped unambiguously to the unigene database, respectively. Most of the tags were expressed at similar levels, showing a histone acetylation during root growth and development, which will lead to a better understanding of the mechanism controlling root development.

  17. PLANT MICROBIOME. Salicylic acid modulates colonization of the root microbiome by specific bacterial taxa.

    Science.gov (United States)

    Lebeis, Sarah L; Paredes, Sur Herrera; Lundberg, Derek S; Breakfield, Natalie; Gehring, Jase; McDonald, Meredith; Malfatti, Stephanie; Glavina del Rio, Tijana; Jones, Corbin D; Tringe, Susannah G; Dangl, Jeffery L

    2015-08-21

    Immune systems distinguish "self" from "nonself" to maintain homeostasis and must differentially gate access to allow colonization by potentially beneficial, nonpathogenic microbes. Plant roots grow within extremely diverse soil microbial communities but assemble a taxonomically limited root-associated microbiome. We grew isogenic Arabidopsis thaliana mutants with altered immune systems in a wild soil and also in recolonization experiments with a synthetic bacterial community. We established that biosynthesis of, and signaling dependent on, the foliar defense phytohormone salicylic acid is required to assemble a normal root microbiome. Salicylic acid modulates colonization of the root by specific bacterial families. Thus, plant immune signaling drives selection from the available microbial communities to sculpt the root microbiome.

  18. Nucleic acid and protein synthesis during lateral root initiation in Marsilea quadrifolia (Marsileaceae)

    Science.gov (United States)

    Lin, B. L.; Raghavan, V.

    1991-01-01

    The pattern of DNA, RNA, and protein synthesis during lateral root initiation in Marsilea quadrifolia L. was monitored by autoradiography of incorporated of 3H-thymidine, 3H-uridine, and 3H-leucine, respectively. DNA synthesis was associated with the enlargement of the lateral root initial prior to its division. Consistent with histological studies, derivatives of the lateral root initial as well as the cells of the adjacent inner cortex and pericycle of the parent root also continued to synthesize DNA. RNA and protein synthetic activities were found to be higher in the lateral root initials than in the endodermal initials of the same longitudinal layer. The data suggest a role for nucleic acid and protein synthesis during cytodifferentiation of a potential endodermal cell into a lateral root initial.

  19. Function and regulation of transcription factors involved in root apical meristem and stem cell maintenance

    Directory of Open Access Journals (Sweden)

    Rebecca Corinna Drisch

    2015-07-01

    Full Text Available Plant roots are essential for overall plant development, growth and performance by providing anchorage in the soil and uptake of nutrients and water. The primary root of higher plants derives from a group of pluripotent, mitotically active stem cells residing in the root apical meristem (RAM which provides the basis for growth, development and regeneration of the root. The stem cells in the Arabidopsis thaliana RAM are surrounding the quiescent center (QC, which consists of a group of rarely dividing cells. The QC maintains the stem cells in a non-cell-autonomous manner and prevents them from differentiation. The necessary dynamic but also tight regulation of the transition from stem cell fate to differentiation most likely requires complex regulatory mechanisms to integrate external and internal cues. Transcription factors play a central role in root development and are regulated by phytohormones, small signaling molecules and miRNAs. In this review we give a comprehensive overview about the function and regulation of specific transcription factors controlling stem cell fate and root apical meristem maintenance and discuss the possibility of TF complex formation, subcellular translocations and cell-to-cell movement functioning as another level of regulation.

  20. Regulation of root hair cell differentiation by R3 MYB transcription factors in tomato and Arabidopsis.

    Science.gov (United States)

    Tominaga-Wada, Rumi; Wada, Takuji

    2014-01-01

    CAPRICE (CPC) encodes a small protein with an R3 MYB motif and regulates root hair and trichome cell differentiation in Arabidopsis thaliana. Six additional CPC-like MYB proteins including TRIPTYCHON (TRY), ENHANCER OF TRY AND CPC1 (ETC1), ENHANCER OF TRY AND CPC2 (ETC2), ENHANCER OF TRY AND CPC3/CPC-LIKE MYB3 (ETC3/CPL3), TRICHOMELESS1 (TCL1), and TRICHOMELESS2/CPC-LIKE MYB4 (TCL2/CPL4) also have the ability to regulate root hair and/or trichome cell differentiation in Arabidopsis. In this review, we describe our latest findings on how CPC-like MYB transcription factors regulate root hair cell differentiation. Recently, we identified the tomato SlTRY gene as an ortholog of the Arabidopsis TRY gene. Transgenic Arabidopsis plants harboring SlTRY produced more root hairs, a phenotype similar to that of 35S::CPC transgenic plants. CPC is also known to be involved in anthocyanin biosynthesis. Anthocyanin accumulation was repressed in the SlTRY transgenic plants, suggesting that SlTRY can also influence anthocyanin biosynthesis. We concluded that tomato and Arabidopsis partially use similar transcription factors for root hair cell differentiation, and that a CPC-like R3 MYB may be a key common regulator of plant root-hair development.

  1. A Small GTPase Activator Protein Interacts with Cytoplasmic Phytochromes in Regulating Root Development*

    Science.gov (United States)

    Shin, Dong Ho; Cho, Man-Ho; Kim, Tae-Lim; Yoo, Jihye; Kim, Jeong-Il; Han, Yun-Jeong; Song, Pill-Soon; Jeon, Jong-Seong; Bhoo, Seong Hee; Hahn, Tae-Ryong

    2010-01-01

    Phytochromes enable plants to sense light information and regulate developmental responses. Phytochromes interact with partner proteins to transmit light signals to downstream components for plant development. PIRF1 (phytochrome-interacting ROP guanine-nucleotide exchange factor (RopGEF 1)) functions as a light-signaling switch regulating root development through the activation of ROPs (Rho-like GTPase of plant) in the cytoplasm. In vitro pulldown and yeast two-hybrid assays confirmed the interaction between PIRF1 and phytochromes. PIRF1 interacted with the N-terminal domain of phytochromes through its conserved PRONE (plant-specific ROP nucleotide exchanger) region. PIRF1 also interacted with ROPs and activated them in a phytochrome-dependent manner. The Pr form of phytochrome A enhanced the RopGEF activity of PIRF1, whereas the Pfr form inhibited it. A bimolecular fluorescence complementation analysis demonstrated that PIRF1 was localized in the cytoplasm and bound to the phytochromes in darkness but not in light. PIRF1 loss of function mutants (pirf1) of Arabidopsis thaliana showed a longer root phenotype in the dark. In addition, both PIRF1 overexpression mutants (PIRF1-OX) and phytochrome-null mutants (phyA-211 and phyB-9) showed retarded root elongation and irregular root hair formation, suggesting that PIRF1 is a negative regulator of phytochrome-mediated primary root development. We propose that phytochrome and ROP signaling are interconnected through PIRF1 in regulating the root growth and development in Arabidopsis. PMID:20551316

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

    Science.gov (United States)

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

    1990-01-01

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

  3. Modelling metal accumulation using humic acid as a surrogate for plant roots.

    Science.gov (United States)

    Le, T T Yen; Swartjes, Frank; Römkens, Paul; Groenenberg, Jan E; Wang, Peng; Lofts, Stephen; Hendriks, A Jan

    2015-04-01

    Metal accumulation in roots was modelled with WHAM VII using humic acid (HA) as a surrogate for root surface. Metal accumulation was simulated as a function of computed metal binding to HA, with a correction term (E(HA)) to account for the differences in binding site density between HA and root surface. The approach was able to model metal accumulation in roots to within one order of magnitude for 95% of the data points. Total concentrations of Mn in roots of Vigna unguiculata, total concentrations of Ni, Zn, Cu and Cd in roots of Pisum sativum, as well as internalized concentrations of Cd, Ni, Pb and Zn in roots of Lolium perenne, were significantly correlated to the computed metal binding to HA. The method was less successful at modelling metal accumulation at low concentrations and in soil experiments. Measured concentrations of Cu internalized in L. perenne roots were not related to Cu binding to HA modelled and deviated from the predictions by over one order of magnitude. The results indicate that metal uptake by roots may under certain conditions be influenced by conditional physiological processes that cannot simulated by geochemical equilibrium. Processes occurring in chronic exposure of plants grown in soil to metals at low concentrations complicate the relationship between computed metal binding to HA and measured metal accumulation in roots.

  4. Gibberellic acid increases secondary metabolite production in Echinacea purpurea hairy roots.

    Science.gov (United States)

    Abbasi, Bilal H; Stiles, Amanda R; Saxena, Praveen K; Liu, Chun-Zhao

    2012-12-01

    Gibberellic acid (GA(3)) is reported to have diverse effects on hairy root cultures of many plant species; therefore, the effects of GA(3) on the growth, secondary metabolite production (caffeic acid derivatives and lignin), phenylalanine ammonia lyase (PAL) activity, and free radical scavenging activity of light-grown Echinacea purpurea L. hairy roots were investigated. Eight concentrations of GA(3), ranging from 0.005 to 1.0 μM, were added to shake flask cultures. The moderate GA(3) concentration, 0.025 μM, resulted in the highest concentrations of cichoric acid, caftaric acid, and chlorogenic acid, as well as increased PAL activity, cell viability, and free radical scavenging activity, while higher and lower GA(3) concentrations resulted in reduced levels compared to the control (lacking GA(3)). The moderate GA(3) concentration also affected root morphogenesis; supplementation with 0.025 μM GA(3) resulted in the development of thick, dense, purple-colored roots, while roots exposed to the higher and lower concentrations of GA(3) were thin and off-white. This study demonstrates that supplementation with GA(3) may be an excellent strategy to optimize the production of secondary metabolites from E. purpurea hairy root cultures; however, the GA(3) concentration is a critical factor.

  5. Complex regulation of Arabidopsis AGR1/PIN2-mediated root gravitropic response and basipetal auxin transport by cantharidin-sensitive protein phosphatases

    Science.gov (United States)

    Shin, Heungsop; Shin, Hwa-Soo; Guo, Zibiao; Blancaflor, Elison B.; Masson, Patrick H.; Chen, Rujin

    2005-01-01

    Polar auxin transport, mediated by two distinct plasma membrane-localized auxin influx and efflux carrier proteins/complexes, plays an important role in many plant growth and developmental processes including tropic responses to gravity and light, development of lateral roots and patterning in embryogenesis. We have previously shown that the Arabidopsis AGRAVITROPIC 1/PIN2 gene encodes an auxin efflux component regulating root gravitropism and basipetal auxin transport. However, the regulatory mechanism underlying the function of AGR1/PIN2 is largely unknown. Recently, protein phosphorylation and dephosphorylation mediated by protein kinases and phosphatases, respectively, have been implicated in regulating polar auxin transport and root gravitropism. Here, we examined the effects of chemical inhibitors of protein phosphatases on root gravitropism and basipetal auxin transport, as well as the expression pattern of AGR1/PIN2 gene and the localization of AGR1/PIN2 protein. We also examined the effects of inhibitors of vesicle trafficking and protein kinases. Our data suggest that protein phosphatases, sensitive to cantharidin and okadaic acid, are likely involved in regulating AGR1/PIN2-mediated root basipetal auxin transport and gravitropism, as well as auxin response in the root central elongation zone (CEZ). BFA-sensitive vesicle trafficking may be required for the cycling of AGR1/PIN2 between plasma membrane and the BFA compartment, but not for the AGR1/PIN2-mediated root basipetal auxin transport and auxin response in CEZ cells.

  6. Push-pull strategy in the regulation of postembryonic root development.

    Science.gov (United States)

    Choe, Goh; Lee, Ji-Young

    2017-02-01

    Unlike animals, plants continue to grow throughout their lives. The stem cell niche, protected in meristems of shoots and roots, enables this process. In the root, stem cells produce precursors for highly organized cell types via asymmetric cell divisions. These precursors, which are "transit-amplifying cells," actively divide for several rounds before entering into differentiation programs. In this review, we highlight positive feedback regulation between shoot- and root-ward signals during the postembryonic root growth, which is reminiscent of a "push-pull strategy" in business parlance. This property of molecular networks underlies the regulation of stem cells and their organizer, the "quiescent center," as well as of the signaling between stem cell niche, transit-amplifying cells, and beyond. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. Local positive feedback regulation determines cell shape in root hair cells.

    Science.gov (United States)

    Takeda, Seiji; Gapper, Catherine; Kaya, Hidetaka; Bell, Elizabeth; Kuchitsu, Kazuyuki; Dolan, Liam

    2008-02-29

    The specification and maintenance of growth sites are tightly regulated during cell morphogenesis in all organisms. ROOT HAIR DEFECTIVE 2 reduced nicotinamide adenine dinucleotide phosphate (RHD2 NADPH) oxidase-derived reactive oxygen species (ROS) stimulate a Ca2+ influx into the cytoplasm that is required for root hair growth in Arabidopsis thaliana. We found that Ca2+, in turn, activated the RHD2 NADPH oxidase to produce ROS at the growing point in the root hair. Together, these components could establish a means of positive feedback regulation that maintains an active growth site in expanding root hair cells. Because the location and stability of growth sites predict the ultimate form of a plant cell, our findings demonstrate how a positive feedback mechanism involving RHD2, ROS, and Ca2+ can determine cell shape.

  8. Long-distance signals positively regulate the expression of iron uptake genes in tobacco roots.

    Science.gov (United States)

    Enomoto, Yusuke; Hodoshima, Hirotaka; Shimada, Hiroaki; Shoji, Kazuhiro; Yoshihara, Toshihiro; Goto, Fumiyuki

    2007-12-01

    Long-distance signals generated in shoots are thought to be associated with the regulation of iron uptake from roots; however, the signaling mechanism is still unknown. To elucidate whether the signal regulates iron uptake genes in roots positively or negatively, we analyzed the expressions of two representative iron uptake genes: NtIRT1 and NtFRO1 in tobacco (Nicotiana tabacum L.) roots, after shoots were manipulated in vitro. When iron-deficient leaves were treated with Fe(II)-EDTA, the expressions of both genes were significantly reduced; nevertheless iron concentration in the roots maintained a similar level to that in roots grown under iron-deficient conditions. Next, all leaves from tobacco plants grown under the iron-deficient condition were excised. The expression of two genes were quickly reduced below half within 2 h after the leaf excision and gradually disappeared by the end of a 24-h period. The NtIRT1 expression was compared among the plants whose leaves were cut off in various patterns. The expression increased in proportion to the dry weight of iron-deficient leaves, although no relation was observed between the gene expression and the position of excised leaves. Interestingly, the NtIRT1 expression in hairy roots increased under the iron-deficient condition, suggesting that roots also have the signaling mechanism of iron status as well as shoots. Taken together, these results indicate that the long-distance signal generated in iron-deficient tissues including roots is a major factor in positive regulation of the expression of NtIRT1 and NtFRO1 in roots, and that the strength of the signal depends on the size of plants.

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

    Directory of Open Access Journals (Sweden)

    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.

  10. Ethylene regulates root growth through effects on auxin biosynthesis and transport-dependent auxin distribution

    OpenAIRE

    2007-01-01

    In plants, each developmental process integrates a network of signaling events that are regulated by different phytohormones, and interactions among hormonal pathways are essential to modulate their effect. Continuous growth of roots results from the postembryonic activity of cells within the root meristem that is controlled by the coordinated action of several phytohormones, including auxin and ethylene. Although their interaction has been studied intensively, the molecular and cellular mech...

  11. Establishment of Salvia officinalis L. hairy root cultures for the production of rosmarinic acid.

    Science.gov (United States)

    Grzegorczyk, Izabela; Królicka, Aleksandra; Wysokińska, Halina

    2006-01-01

    Shoots of Salvia officinalis, a medicinally important plant, were infected with Agrobacterium rhizogenes strains ATCC 15834 and A4 which led to the induction of hairy roots in 57% and 37% of the explants, respectively. Seven lines of hairy roots were established in WP liquid medium under light and dark conditions. The transformed nature of the root lines was confirmed by polymerase chain reaction using rolB and rolC specific primers. Transformed root cultures of Salvia officinalis showed variations in biomass and rosmarinic acid production depending on the bacterial strain used for transformation and the root line analyzed. Both parameters (growth and rosmarinic acid content) of ATCC 15834-induced lines were significantly higher than the A4-induced lines. The maximum accumulation of rosmarinic acid (about 45 mg g(-1) of dry weight) was achieved by hairy root line 1 (HR-1) at the end of the culture period (45-50 days). The level was significantly higher than that found in untransformed root culture (19 mg g(-10 of dry wt).

  12. Correlation between root respiration and the levels of biomass and glycyrrhizic acid in Glycyrrhiza uralensis.

    Science.gov (United States)

    Liu, Wenlan; Sun, Zhirong; Qu, Jixu; Yang, Chunning; Zhang, Xiaomin; Wei, Xinxin

    2017-09-01

    The aim of the present study was to investigate the correlation between root respiration and the levels of biomass and glycyrrhizic acid in Glycyrrhiza uralensis. Root respiration was determined using a biological oxygen analyzer. Respiration-related enzymes including glucose-6-phosphate dehydrogenase plus 6-phosphogluconate dehydrogenase, phosphohexose isomerase and succinate dehydrogenase, and respiratory pathways were evaluated. Biomass was determined by a drying-weighing method. In addition, the percentage of glycyrrhizic acid was detected using high-performance liquid chromatography. The association between root respiration and the levels of biomass and glycyrrhizic acid was investigated. The glycolysis pathway (EMP), tricarboxylic acid cycle (TCA) and pentose phosphate (PPP) pathway acted concurrently in the roots of G. uralensis. Grey correlation analysis showed that TCA had the strongest correlation (correlation coefficient, 0.8003) with biomass. Starch and acetyl coenzyme A had the closest association with above-ground biomass, while soluble sugar correlated less strongly with above-ground biomass. Grey correlation analysis between biochemical pathways and the intermediates showed that pyruvic acid had the strongest correlation with EMP, while acetyl coenzyme A correlated most strongly with TCA. Among the intermediates and pathways, pyruvic acid and EMP exhibited the greatest correlation with glycyrrhizic acid, while acetyl coenzyme A and TCA correlated with glycyrrhizic acid less closely. The results of this study may aid the cultivation of G. uralensis. However, these results require verification in further studies.

  13. [Effect of phosphorus deficiency on activity of acid phosphatase exuded by wheat roots].

    Science.gov (United States)

    Sun, Haiguo; Zhang, Fusuo

    2002-03-01

    The activity of acid phosphatase exuded by roots, the tissue location of the enzyme, and the relationship between the enzyme activity and phosphorus efficiency of wheat were studied. The results showed that the activity of acid phosphatase exuded by wheat 81(85)5-3-3-3 and NC37 under P-sufficiency treat were lower than those under P-deficiency, and the enzyme activity of the former variety was significantly higher than that of the latter. There was a significant difference in the enzyme activity among 12 wheat genotypes grown under P-deficiency treat. Acid phosphatase was exuded by epidermis cell of root, especially by epidermal cell of root apex. Thus, there was a linear relationship between the enzyme activity and the surface area of root or the number of root apexes. It implied that the enzyme activity was markedly related to the size of root system. The linear relationship between relative grain yield and acid phosphatase activity was significant. It indicates that the enzyme activity could be used as an early indicator to select P-efficient wheat genotypes.

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

    Science.gov (United States)

    Glinka, Z

    1977-05-01

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

  15. Role of Root Exudates in Adaptative Reactions of Buckwheat Plants in Aluminium-acid Stress

    Directory of Open Access Journals (Sweden)

    A.E. Smirnov

    2014-03-01

    Full Text Available Aliminium toxicity is major limiting factor of crop production in acidic soils. It is known that mechanisms of toxic effects of aluminium are differing in biochemical characters, research of aluminium toxicity complicated by variety of its chemical forms and migration in soil and water ability. The root exudates qualitative composition of common buckwheat was evaluated. Organic complexing agents – oxalic acid and phenolic compounds were revealed. The role of these complexing agents in the buckwheat aluminium resistance under acidic stress, participation in processes of external and internal detoxification was shown. Spectrophometric assay revealed an increase in root secretion of oxalic acid by 2.5 times and decrease in content of phenolic compounds in root exudates solution by 3 times upon aluminium (50 µM treatment. In the meanwhile the same concentration of the metal had induced phenylalanine ammonia-lyase activity by 2 times.

  16. Plant Nitrogen Acquisition Under Low Availability: Regulation of Uptake and Root Architecture.

    Science.gov (United States)

    Kiba, Takatoshi; Krapp, Anne

    2016-04-01

    Nitrogen availability is a major factor determining plant growth and productivity. Plants acquire nitrogen nutrients from the soil through their roots mostly in the form of ammonium and nitrate. Since these nutrients are scarce in natural soils, plants have evolved adaptive responses to cope with the environment. One of the most important responses is the regulation of nitrogen acquisition efficiency. This review provides an update on the molecular determinants of two major drivers of the nitrogen acquisition efficiency: (i) uptake activity (e.g. high-affinity nitrogen transporters) and (ii) root architecture (e.g. low-nitrogen-availability-specific regulators of primary and lateral root growth). Major emphasis is laid on the regulation of these determinants by nitrogen supply at the transcriptional and post-transcriptional levels, which enables plants to optimize nitrogen acquisition efficiency under low nitrogen availability.

  17. The Effect Of Some Plant Growth Regulators And Their Combination With Methyl Jasmonate On Anthocyanin Formation In Roots Of Kalanchoe Blossfeldiana

    Directory of Open Access Journals (Sweden)

    Góraj Justyna

    2014-12-01

    Full Text Available In this study, we investigated the effect of plant growth regulators (PGRs - auxins, gibberellin, cytokinin, abscisic acid, brassinosteroid, ethylene and their interaction with methyl jasmonate (JA-Me applied to roots of the whole plants Kalanchoe blossfeldiana on the accumulation of anthocyanins in roots. The highest stimulation of anthocyanins synthesis was stated with application of JA-Me alone. In response to treatments with the other tested PGRs, the content of anthocyanins in roots of a whole plant was different depending on the concentration of the PGR when being applied alone or together with JA-Me. Auxin, indole-3-acetic acid (IAA at a concentration of 50 mg·L-1, indole-3-butyric acid (IBA at 5 mg·L-1 and abscisic acid (ABA at 10 mg·L-1 induced anthocyanin accumulation with approximately 60-115% compared to the control while 24-epibrassinolid (epiBL, gibberellic acid (GA3 and 6-benzylaminopurine (BAP had no effect on the anthocyanin accumulation. The simultaneous administration of the PGRs with JA-Me usually resulted in the accumulation of anthocyanins in roots in a manner similar to that caused by JA-Me. PGRs applied to isolated roots did not stimulate anthocyanin accumulation, except for the combination of JA-Me with 50 mg·L-1 IAA.

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

    Science.gov (United States)

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

    2015-11-01

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

  19. Root-fed Salicylic Acid in Grape Involves the Response Caused by Aboveground High Temperature

    Institute of Scientific and Technical Information of China (English)

    Hong-Tao Liu; Yue-Ping Liu; Wei-Dong Huang

    2008-01-01

    In order to investigate the transportation and distribution of salicylic acid (SA) from root to aboveground tissues in response to high temperature, the roots of grape plant were fed with 14C-SA before high temperature treatment. Radioactivity results showed that progressive increase in SA transportation from root to aboveground as compared with the control varied exactly with the heat treatment time. Radioactivity results of leaves at different stem heights indicated that the increase in SA amount at the top and middle leaves during the early period was most significant in comparison with the bottom leaves. The up-transportation of SA from root to aboveground tissues was dependent on xylem rather than phloem. Auto-radiographs of whole grape plants strongly approved the conclusions drawn above. Root-derived SA was believed to be a fundamental source in response to aboveground high temperature.

  20. Regulation of root hair cell differentiation by R3 MYB transcription factors in tomato and Arabidopsis

    OpenAIRE

    Tominaga-Wada, Rumi; Wada, Takuji

    2014-01-01

    CAPRICE (CPC) encodes a small protein with an R3 MYB motif and regulates root hair and trichome cell differentiation in Arabidopsis thaliana. Six additional CPC-like MYB proteins including TRIPTYCHON (TRY), ENHANCER OF TRY AND CPC1 (ETC1), ENHANCER OF TRY AND CPC2 (ETC2), ENHANCER OF TRY AND CPC3/CPC-LIKE MYB3 (ETC3/CPL3), TRICHOMELESS1 (TCL1), and TRICHOMELESS2/CPC-LIKE MYB4 (TCL2/CPL4) also have the ability to regulate root hair and/or trichome cell differentiation in Arabidopsis. In this r...

  1. Plasticity regulators modulate specific root traits in discrete nitrogen environments.

    Directory of Open Access Journals (Sweden)

    Miriam L Gifford

    Full Text Available Plant development is remarkably plastic but how precisely can the plant customize its form to specific environments? When the plant adjusts its development to different environments, related traits can change in a coordinated fashion, such that two traits co-vary across many genotypes. Alternatively, traits can vary independently, such that a change in one trait has little predictive value for the change in a second trait. To characterize such "tunability" in developmental plasticity, we carried out a detailed phenotypic characterization of complex root traits among 96 accessions of the model Arabidopsis thaliana in two nitrogen environments. The results revealed a surprising level of independence in the control of traits to environment - a highly tunable form of plasticity. We mapped genetic architecture of plasticity using genome-wide association studies and further used gene expression analysis to narrow down gene candidates in mapped regions. Mutants in genes implicated by association and expression analysis showed precise defects in the predicted traits in the predicted environment, corroborating the independent control of plasticity traits. The overall results suggest that there is a pool of genetic variability in plants that controls traits in specific environments, with opportunity to tune crop plants to a given environment.

  2. Characterization of Lipids and Fatty Acid Methyl Ester Contents in Leaves and Roots of Crocus vallicola

    OpenAIRE

    YAYLI, Nurettin; KIRAN, Zerrin; SEYMEN, Hasan; GENÇ, Hasan

    2001-01-01

    The chemical composition of the fatty acids methyl esters (FAMEs) and other lipids in leaves and roots of Crocusvallicola were analyzed by gas chromatography-mass spectrometry(GC-MS). In this work, twenty-eight compounds, including 22 FAMEs, 1 aldehyde, 3 hydrocarbons (substitute alkane and alkene), 2 alcohols in the leaves and twenty-one compounds (17 FAMEs, 1 anhydride, 1 substitute alcohol, 1 ketone, 1 substitute amide) in the roots were identified by GC-MS from C. vallicola. Th...

  3. Effect of oxygen deficiency on nitrogen assimilation and amino acid metabolism of soybean root segments.

    Science.gov (United States)

    Oliveira, Halley Caixeta; Sodek, Ladaslav

    2013-02-01

    Plants submitted to O(2) deficiency present a series of biochemical modifications, affecting overall root metabolism. Here, the effect of hypoxia on the metabolic fate of (15)N derived from (15)NO(3)(-), (15)NO(2)(-) and (15)NH(4)(+) in isolated soybean root segments was followed by gas chromatography-mass spectrometry, to provide a detailed analysis of nitrogen assimilation and amino acid biosynthesis under hypoxia. O(2) deficiency decreased the uptake of the nitrogen sources from the solution, as ratified by the lower (15)NO(3)(-) and (15)NH(4)(+) enrichment in the root segments. Moreover, analysis of endogenous NO(2)(-) and (15)NH(4)(+) levels suggested a slower metabolism of these ions under hypoxia. Accordingly, regardless of the nitrogen source, hypoxia reduced total (15)N incorporation into amino acids. Analysis of (15)N enrichment patterns and amino acid levels suggest a redirecting of amino acid metabolism to alanine and γ-aminobutyric acid synthesis under hypoxia and a differential sensitivity of individual amino acid pathways to this stress. Moreover, the role of glutamine synthetase in nitrogen assimilation both under normoxia and hypoxia was ratified. In comparison with (15)NH(4)(+), (15)NO(2)(-) assimilation into amino acids was more strongly affected by hypoxia and NO(2)(-) accumulated in root segments during this stress, indicating that nitrite reductase may be an additional limiting step. NO(2)(-) accumulation was associated with a higher nitric oxide emission. (15)NO(3)(-) led to much lower (15)N incorporation in both O(2) conditions, probably due to the limited nitrate reductase activity of the root segments. Overall, the present work shows that profound alterations of root nitrogen metabolism occur during hypoxic stress.

  4. ABA-mediated ROS in mitochondria regulate root meristem activity by controlling PLETHORA expression in Arabidopsis.

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    Li Yang

    2014-12-01

    Full Text Available Although research has determined that reactive oxygen species (ROS function as signaling molecules in plant development, the molecular mechanism by which ROS regulate plant growth is not well known. An aba overly sensitive mutant, abo8-1, which is defective in a pentatricopeptide repeat (PPR protein responsible for the splicing of NAD4 intron 3 in mitochondrial complex I, accumulates more ROS in root tips than the wild type, and the ROS accumulation is further enhanced by ABA treatment. The ABO8 mutation reduces root meristem activity, which can be enhanced by ABA treatment and reversibly recovered by addition of certain concentrations of the reducing agent GSH. As indicated by low ProDR5:GUS expression, auxin accumulation/signaling was reduced in abo8-1. We also found that ABA inhibits the expression of PLETHORA1 (PLT1 and PLT2, and that root growth is more sensitive to ABA in the plt1 and plt2 mutants than in the wild type. The expression of PLT1 and PLT2 is significantly reduced in the abo8-1 mutant. Overexpression of PLT2 in an inducible system can largely rescue root apical meristem (RAM-defective phenotype of abo8-1 with and without ABA treatment. These results suggest that ABA-promoted ROS in the mitochondria of root tips are important retrograde signals that regulate root meristem activity by controlling auxin accumulation/signaling and PLT expression in Arabidopsis.

  5. ABA-mediated ROS in mitochondria regulate root meristem activity by controlling PLETHORA expression in Arabidopsis.

    Science.gov (United States)

    Yang, Li; Zhang, Jing; He, Junna; Qin, Yingying; Hua, Deping; Duan, Ying; Chen, Zhizhong; Gong, Zhizhong

    2014-12-01

    Although research has determined that reactive oxygen species (ROS) function as signaling molecules in plant development, the molecular mechanism by which ROS regulate plant growth is not well known. An aba overly sensitive mutant, abo8-1, which is defective in a pentatricopeptide repeat (PPR) protein responsible for the splicing of NAD4 intron 3 in mitochondrial complex I, accumulates more ROS in root tips than the wild type, and the ROS accumulation is further enhanced by ABA treatment. The ABO8 mutation reduces root meristem activity, which can be enhanced by ABA treatment and reversibly recovered by addition of certain concentrations of the reducing agent GSH. As indicated by low ProDR5:GUS expression, auxin accumulation/signaling was reduced in abo8-1. We also found that ABA inhibits the expression of PLETHORA1 (PLT1) and PLT2, and that root growth is more sensitive to ABA in the plt1 and plt2 mutants than in the wild type. The expression of PLT1 and PLT2 is significantly reduced in the abo8-1 mutant. Overexpression of PLT2 in an inducible system can largely rescue root apical meristem (RAM)-defective phenotype of abo8-1 with and without ABA treatment. These results suggest that ABA-promoted ROS in the mitochondria of root tips are important retrograde signals that regulate root meristem activity by controlling auxin accumulation/signaling and PLT expression in Arabidopsis.

  6. The usage of growth regulator in the rooting of japanese wisteria tree

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    Francieli Gonçalves Azeredo

    2015-12-01

    Full Text Available Wisteria floribunda, known as wisteria, is a woody climbing plant with inflorescence raceme type, stalky supported, which provides value for the cultivation towards ornamental purposes. Its propagation occurs via seeds or stem cuttings. The low rate of seed germination makes the vegetative propagation a more efficient method. The presented work verified the influence of synthetic auxin application, indole butyric acid (IBA, in different concentrations, such as its application way, talc or solution, in the rooting of wisteria cuttings. With branches of stock plants, collected in November 2012, were made cuttings of approximately 10 cm length, 0.5 cm diameter and with two leaves. After disinfection, the base of the cuttings were treated with: 0 mg L-1; 1000 mg L-1 and 2000 mg L-1 via IBA in solution and, 0 mg kg-1; 1000 mg kg-1 e 2000 mg kg-1 via IBA in talc. Vermiculite was the subtract used for all treatments. 63 days after the installation, the percentage of rooted cuttings was evaluated, live, with calluses and dead; the number of roots per cuttings and the length of the largest roots per cuttings. The best results were obtained with treated cuttings of 2000 mg kg-1 (78.75% and 73.75% of rooting therefore both ways of application of IBA are efficient towards the rooting induction. The application in the form of talc is indicated for the induction of a greater number of roots per cutting.

  7. Alkaline stress and iron deficiency regulate iron uptake and riboflavin synthesis gene expression differently in root and leaf tissue: implications for iron deficiency chlorosis.

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    Hsieh, En-Jung; Waters, Brian M

    2016-10-01

    Iron (Fe) is an essential mineral that has low solubility in alkaline soils, where its deficiency results in chlorosis. Whether low Fe supply and alkaline pH stress are equivalent is unclear, as they have not been treated as separate variables in molecular physiological studies. Additionally, molecular responses to these stresses have not been studied in leaf and root tissues simultaneously. We tested how plants with the Strategy I Fe uptake system respond to Fe deficiency at mildly acidic and alkaline pH by measuring root ferric chelate reductase (FCR) activity and expression of selected Fe uptake genes and riboflavin synthesis genes. Alkaline pH increased cucumber (Cucumis sativus L.) root FCR activity at full Fe supply, but alkaline stress abolished FCR response to low Fe supply. Alkaline pH or low Fe supply resulted in increased expression of Fe uptake genes, but riboflavin synthesis genes responded to Fe deficiency but not alkalinity. Iron deficiency increased expression of some common genes in roots and leaves, but alkaline stress blocked up-regulation of these genes in Fe-deficient leaves. In roots of the melon (Cucumis melo L.) fefe mutant, in which Fe uptake responses are blocked upstream of Fe uptake genes, alkaline stress or Fe deficiency up-regulation of certain Fe uptake and riboflavin synthesis genes was inhibited, indicating a central role for the FeFe protein. These results suggest a model implicating shoot-to-root signaling of Fe status to induce Fe uptake gene expression in roots.

  8. A late embryogenesis abundant protein HVA1 regulated by an inducible promoter enhances root growth and abiotic stress tolerance in rice without yield penalty.

    Science.gov (United States)

    Chen, Yi-Shih; Lo, Shuen-Fang; Sun, Peng-Kai; Lu, Chung-An; Ho, Tuan-Hua D; Yu, Su-May

    2015-01-01

    Regulation of root architecture is essential for maintaining plant growth under adverse environment. A synthetic abscisic acid (ABA)/stress-inducible promoter was designed to control the expression of a late embryogenesis abundant protein (HVA1) in transgenic rice. The background of HVA1 is low but highly inducible by ABA, salt, dehydration and cold. HVA1 was highly accumulated in root apical meristem (RAM) and lateral root primordia (LRP) after ABA/stress treatments, leading to enhanced root system expansion. Water-use efficiency (WUE) and biomass also increased in transgenic rice, likely due to the maintenance of normal cell functions and metabolic activities conferred by HVA1 which is capable of stabilizing proteins, under osmotic stress. HVA1 promotes lateral root (LR) initiation, elongation and emergence and primary root (PR) elongation via an auxin-dependent process, particularly by intensifying asymmetrical accumulation of auxin in LRP founder cells and RAM, even under ABA/stress-suppressive conditions. We demonstrate a successful application of an inducible promoter in regulating the spatial and temporal expression of HVA1 for improving root architecture and multiple stress tolerance without yield penalty.

  9. SOMBRERO, BEARSKIN1, and BEARSKIN2 Regulate Root Cap Maturation in Arabidopsis[C][W

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    Bennett, Tom; van den Toorn, Albert; Sanchez-Perez, Gabino F.; Campilho, Ana; Willemsen, Viola; Snel, Berend; Scheres, Ben

    2010-01-01

    The root cap has a central role in root growth, determining the growth trajectory and facilitating penetration into the soil. Root cap cells have specialized functions and morphologies, and border cells are released into the rhizosphere by specific cell wall modifications. Here, we demonstrate that the cellular maturation of root cap is redundantly regulated by three genes, SOMBRERO (SMB), BEARSKIN1 (BRN1), and BRN2, which are members of the Class IIB NAC transcription factor family, together with the VASCULAR NAC DOMAIN (VND) and NAC SECONDARY WALL THICKENING PROMOTING FACTOR (NST) genes that regulate secondary cell wall synthesis in specialized cell types. Lateral cap cells in smb-3 mutants continue to divide and fail to detach from the root, phenotypes that are independent of FEZ upregulation in smb-3. In brn1-1 brn2-1 double mutants, columella cells fail to detach, while in triple mutants, cells fail to mature in all parts of the cap. This complex genetic redundancy involves differences in expression, protein activity, and target specificity. All three genes have very similar overexpression phenotypes to the VND/NST genes, indicating that members of this family are largely functionally equivalent. Our results suggest that Class IIB NAC proteins regulate cell maturation in cells that undergo terminal differentiation with strong cell wall modifications. PMID:20197506

  10. SOMBRERO, BEARSKIN1, and BEARSKIN2 regulate root cap maturation in Arabidopsis.

    Science.gov (United States)

    Bennett, Tom; van den Toorn, Albert; Sanchez-Perez, Gabino F; Campilho, Ana; Willemsen, Viola; Snel, Berend; Scheres, Ben

    2010-03-01

    The root cap has a central role in root growth, determining the growth trajectory and facilitating penetration into the soil. Root cap cells have specialized functions and morphologies, and border cells are released into the rhizosphere by specific cell wall modifications. Here, we demonstrate that the cellular maturation of root cap is redundantly regulated by three genes, SOMBRERO (SMB), BEARSKIN1 (BRN1), and BRN2, which are members of the Class IIB NAC transcription factor family, together with the VASCULAR NAC DOMAIN (VND) and NAC SECONDARY WALL THICKENING PROMOTING FACTOR (NST) genes that regulate secondary cell wall synthesis in specialized cell types. Lateral cap cells in smb-3 mutants continue to divide and fail to detach from the root, phenotypes that are independent of FEZ upregulation in smb-3. In brn1-1 brn2-1 double mutants, columella cells fail to detach, while in triple mutants, cells fail to mature in all parts of the cap. This complex genetic redundancy involves differences in expression, protein activity, and target specificity. All three genes have very similar overexpression phenotypes to the VND/NST genes, indicating that members of this family are largely functionally equivalent. Our results suggest that Class IIB NAC proteins regulate cell maturation in cells that undergo terminal differentiation with strong cell wall modifications.

  11. Effect of citric acid, tetracycline, and doxycycline on instrumented periodontally involved root surfaces: A SEM study

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    Gurparkash Singh Chahal

    2014-01-01

    Full Text Available Background: A surface smear layer consisting of organic and inorganic material is formed on the root surface following mechanical instrumentation and may inhibit the formation of new connective tissue attachment to the root surface. Modification of the tooth surface by root conditioning has resulted in improved connective tissue attachment and has advanced the goal of reconstructive periodontal treatment. Aim: The aim of this study was to compare the effects of citric acid, tetracycline, and doxycycline on the instrumented periodontally involved root surfaces in vitro using a scanning electron microscope. Settings and Design: A total of 45 dentin samples obtained from 15 extracted, scaled, and root planed teeth were divided into three groups. Materials and Methods: The root conditioning agents were applied with cotton pellets using the "Passive burnishing technique" for 5 minutes. The samples were then examined by the scanning electron microscope. Statistical Analysis Used: The statistical analysis was carried out using Statistical Package for Social Sciences (SPSS Inc., Chicago, IL, version 15.0 for Windows. For all quantitative variables means and standard deviations were calculated and compared. For more than two groups ANOVA was applied. For multiple comparisons post hoc tests with Bonferroni correction was used. Results: Upon statistical analysis the root conditioning agents used in this study were found to be effective in removing the smear layer, uncovering and widening the dentin tubules and unmasking the dentin collagen matrix. Conclusion: Tetracycline HCl was found to be the best root conditioner among the three agents used.

  12. HAWAIIAN SKIRT regulates the quiescent center-independent meristem activity in Arabidopsis roots.

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    Kim, Eun-Sol; Choe, Goh; Sebastian, Jose; Ryu, Kook Hui; Mao, Linyong; Fei, Zhangjun; Lee, Ji-Young

    2016-06-01

    Root apical meristem (RAM) drives post-embryonic root growth by constantly supplying cells through mitosis. It is composed of stem cells and their derivatives, the transit-amplifying (TA) cells. Stem cell organization and its maintenance in the RAM are well characterized, however, their relationships with TA cells remain unclear. SHORTROOT (SHR) is critical for root development. It patterns cell types and promotes the post-embryonic root growth. Defective root growth in the shr has been ascribed to the lack of quiescent center (QC), which maintains the surrounding stem cells. However, our recent investigation indicated that SHR maintains TA cells independently of QC by modulating PHABULOSA (PHB) through miRNA165/6. PHB controls TA cell activity by modulating cytokinin levels and type B Arabidopsis Response Regulator activity, in a dosage-dependent manner. To further understand TA cell regulation, we conducted a shr suppressor screen. With an extensive mutagenesis screen followed by genome sequencing of a pooled F2 population, we discovered two suppressor alleles with mutations in HAWAIIAN SKIRT (HWS). HWS, encoding an F-box protein with kelch domain, is expressed, partly depending on SHR, in the root cap and in the pericycle of the differentiation zone. Interestingly, root growth in the shr hws was more active than the wild-type roots for the first 7 days after germination, without recovering QC. Contrary to shr phb, shr hws did not show a recovery of cytokinin signaling. These indicate that HWS affects QC-independent TA cell activities through a pathway distinctive from PHB. © 2016 Scandinavian Plant Physiology Society.

  13. Final Report: Regulation and Function of Two Cell Wall protein Genes in Me Dicago Roots and Root Nodules, August 1, 1995 - January 31, 1999

    Energy Technology Data Exchange (ETDEWEB)

    Cooper, James B.

    2000-05-08

    During the period of DOE funding we synthesized several PRP peptides, generated rabbit antisera against two PRP repeats found in early nodulin PRPs, and developed confocal microscopy methods for root immunohistochemistry. Using the antibodies, we completed extensive descriptive studies of PRP deposition in medic and alfalfa roots showing that PRPs deposition is developmentally regulated in roots and spatially restricted within the walls of specific root tissues. Domain-specific antibodies were isolated from polyclonal sera using peptide affinity chromatography and were then used to demonstrate that nodule-specific epitopes are shared by several nodule-specific proteins. The following provides a more detailed summary of this work.

  14. Nitric Oxide Functions as a Positive Regulator of Root Hair Development

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    Lombardo, María Cristina; Graziano, Magdalena; Polacco, Joseph C

    2006-01-01

    The root epidermis is composed of two cell types: trichoblasts (or hair cells) and atrichoblasts (or non-hair cells). In lettuce (Lactuca sativa cv. Grand Rapids var. Rapidmor oscura) plants grown hydroponically in water, the root epidermis did not form root hairs. The addition of 10 µM sodium nitroprusside (SNP), a nitric oxide (NO) donor, resulted in almost all rhizodermal cells differentiated into root hairs. Treatment with the synthetic auxin 1-naphthyl acetic acid (NAA) displayed a significant increase of root hair formation (RHF) that was prevented by the specific NO scavenger carboxy-PTIO (cPTIO). In Arabidopsis, two mutants have been shown to be defective in NO production and to display altered phenotypes in which NO is implicated. Arabidopsis nos1 has a mutation in an NO synthase structural gene (NOS1), and the nia1 nia2 double mutant is null for nitrate reductase (NR) activity. We observed that both mutants were affected in their capacity of developing root hairs. Root hair elongation was significantly reduced in nos1 and nia1 nia2 mutants as well as in cPTIO-treated wild type plants. A correlation was found between endogenous NO level in roots detected by the fluorescent probe DAF-FM DA and RHF. In Arabidopsis, as well as in lettuce, cPTIO blocked the NAA-induced root hair elongation. Taken together, these results indicate that: (1) NO is a critical molecule in the process leading to RHF and (2) NO is involved in the auxin-signaling cascade leading to RHF. PMID:19521473

  15. Echium acanthocarpum hairy root cultures, a suitable system for polyunsaturated fatty acid studies and production

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    Ravelo Ángel G

    2011-04-01

    Full Text Available Abstract Background The therapeutic and health promoting role of highly unsaturated fatty acids (HUFAs from fish, i.e. eicosapentaenoic acid (EPA, 20:5n-3 and docosahexaenoic acid (DHA, 22:6n-3 are well known. These same benefits may however be shared by some of their precursors, the polyunsaturated fatty acids (PUFAs, such as stearidonic acid (SDA, 18:4 n-3. In order to obtain alternative sources for the large-scale production of PUFAs, new searches are being conducted focusing on higher plants oils which can contain these n-3 and n-6 C18 precursors, i.e. SDA and GLA (18:3n-6, γ-linolenic acid. Results The establishment of the novel Echium acanthocarpum hairy root cultures represents a powerful tool in order to research the accumulation and metabolism of fatty acids (FAs in a plant particularly rich in GLA and SDA. Furthermore, this study constitutes the first example of a Boraginaceae species hairy root induction and establishment for FA studies and production. The dominant PUFAs, 18:2n-6 (LA, linoleic acid and 18:3n-6 (GLA, accounted for about 50% of total FAs obtained, while the n-3 PUFAs, 18:3n-3 (ALA, α-linolenic acid and 18:4n-3 (SDA, represented approximately 5% of the total. Production of FAs did not parallel hairy root growth, and the optimal productivity was always associated with the highest biomass density during the culture period. Assuming a compromise between FA production and hairy root biomass, it was determined that sampling times 4 and 5 gave the most useful FA yields. Total lipid amounts were in general comparable between the different hairy root lines (29.75 and 60.95 mg/g DW, with the major lipid classes being triacylglycerols. The FAs were chiefly stored in the hairy roots with very minute amounts being released into the liquid nutrient medium. Conclusions The novel results presented here show the utility and high potential of E. acanthocarpum hairy roots. They are capable of biosynthesizing and accumulating a large

  16. Siderophore and organic acid production in root nodule bacteria.

    Science.gov (United States)

    Carson, K C; Holliday, S; Glenn, A R; Dilworth, M J

    1992-01-01

    Nineteen strains of root nodule bacteria were grown under various iron regimes (0.1, 1.0 and 20 microM added iron) and tested for catechol and hydroxamate siderophore production and the excretion of malate and citrate. The growth response of the strains to iron differed markedly. For 12 strains (Bradyrhizobium strains NC92B and 32H1, B. japonicum USDA110 and CB1809, B. lupini WU8, cowpea Rhizobium NGR234, Rhizobium meliloti strains U45 and CC169, Rhizobium leguminosarum bv viciae WU235 and Rhizobium leguminosarum bv trifolii strains TA1, T1 and WU95) the mean generation time showed no variation with the 200-fold increase in iron concentration. In contrast, in Bradyrhizobium strains NC921, CB756 and TAL1000, B. japonicum strain 61A76 and R. leguminosarum bv viciae MNF300 there was a 2-5 fold decrease in growth rate at low iron. R. meliloti strains WSM419 and WSM540 showed decreased growth at high iron. All strains of root nodule bacteria tested gave a positive CAS (chrome azurol S) assay for siderophore production. No catechol-type siderophores were found in any strain, and only R. leguminosarum bv trifolii T1 and bv viciae WU235 produced hydroxamate under low iron (0.1 and 1.0 microM added iron). Malate was excreted by all strains grown under all iron regimes. Citrate was excreted by B. japonicum USDA110 and B. lupini WU8 in all iron concentrations, while Bradyrhizobium TAL1000, R. leguminosarum bv viciae MNF300 and B. japonicum 61A76 only produced citrate under low iron (0.1 and/or 1.0 microM added iron) during the stationary phase of growth.

  17. OPDA has key role in regulating plant susceptibility to the root-knot nematode Meloidogyne hapla in Arabidopsis

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    Cynthia Gleason

    2016-10-01

    Full Text Available Jasmonic acid (JA is a plant hormone that plays important roles in regulating plant defenses against necrotrophic pathogens and herbivorous insects, but the role of JA in mediating the plant responses to root-knot nematodes has been unclear. Here we show that an application of either methyl jasmonate (MeJA or the JA-mimic coronatine (COR on Arabidopsis significantly reduced the number of galls caused by the root-knot nematode Meloidogyne hapla. Interestingly, the MeJA-induced resistance was independent of the JA-receptor COI1 (CORONATINE INSENSITIVE 1. The MeJA-treated plants accumulated the JA precursor cis-(+-12-oxo-phytodienoic acid (OPDA in addition to JA/JA-Isoleucine, indicating a positive feedback loop in JA biosynthesis. Using mutants in the JA-biosynthetic pathway, we found that plants deficient in the biosynthesis of JA and OPDA were hyper-susceptible to M. hapla. However, the opr3 mutant, which cannot convert OPDA to JA, exhibited wild-type levels of nematode galling. In addition, mutants in the JA-biosynthesis and perception which lie downstream of opr3 also displayed wild-type levels of galling. The data puts OPR3 (OPDA reductase 3 as the branch point between hyper-susceptibility and wild-type like levels of disease. Overall, the data suggests that the JA precursor, OPDA, plays a role in regulating plant defense against nematodes.

  18. Quantification and enzyme targets of fatty acid amides from duckweed root exudates involved in the stimulation of denitrification.

    Science.gov (United States)

    Sun, Li; Lu, Yufang; Kronzucker, Herbert J; Shi, Weiming

    2016-07-01

    Fatty acid amides from plant root exudates, such as oleamide and erucamide, have the ability to participate in strong plant-microbe interactions, stimulating nitrogen metabolism in rhizospheric bacteria. However, mechanisms of secretion of such fatty acid amides, and the nature of their stimulatory activities on microbial metabolism, have not been examined. In the present study, collection, pre-treatment, and determination methods of oleamide and erucamide in duckweed root exudates are compared. The detection limits of oleamide and erucamide by gas chromatography (GC) (10.3ngmL(-1) and 16.1ngmL(-1), respectively) are shown to be much lower than those by liquid chromatography (LC) (1.7 and 5.0μgmL(-1), respectively). Quantitative GC analysis yielded five times larger amounts of oleamide and erucamide in root exudates of Spirodela polyrrhiza when using a continuous collection method (50.20±4.32 and 76.79±13.92μgkg(-1) FW day(-1)), compared to static collection (10.88±0.66 and 15.27±0.58μgkg(-1) FW day(-1)). Furthermore, fatty acid amide secretion was significantly enhanced under elevated nitrogen conditions (>300mgL(-1)), and was negatively correlated with the relative growth rate of duckweed. Mechanistic assays were conducted to show that erucamide stimulates nitrogen removal by enhancing denitrification, targeting two key denitrifying enzymes, nitrate and nitrite reductases, in bacteria. Our findings significantly contribute to our understanding of the regulation of nitrogen dynamics by plant root exudates in natural ecosystems. Copyright © 2016 Elsevier GmbH. All rights reserved.

  19. Formin homology 1 (OsFH1) regulates submergence-dependent root hair development in rice plants.

    Science.gov (United States)

    Huang, Jin; Liu, Jingmiao; Han, Chang-Deok

    2013-08-01

    By using a forward genetic approach, a formin homology 1 gene (OsFH1) was identified as a critical regulator of rice root hair development. The phenotypic effect of OsFH1 on root hair development was verified by using three independent mutants, one point mutation and two T-DNA insertions. The study showed that OsFH1 is required for the elongation of root-hairs. However, Osfh1 exhibited growth defect of root hairs only when roots were grown submerged in solution. To understand how OsFH1 impinges on plant responses to root submergence, the growth responses of Osfh1 root hairs to anoxia, carbohydrate supplementation and exogenous hormones (auxin and ethylene) and nutrients (Fe and Pi) were examined. However, none of these treatments rescued the growth defects of Osfhl1 root hairs. This study demonstrates that OsFH1 could be involved in preventing submergence-induced inhibition of root hair growth.

  20. Production of chlorogenic acid and its derivatives in hairy root cultures of Stevia rebaudiana.

    Science.gov (United States)

    Fu, Xiao; Yin, Zhong-Ping; Chen, Ji-Guang; Shangguan, Xin-Chen; Wang, Xiaoqiang; Zhang, Qing-Feng; Peng, Da-Yong

    2015-01-14

    Chlorogenic acid and its derivatives (CADs) are valuable bioactive plant secondary metabolites with many health benefits. In the present study, Stevia rebaudiana hairy root cultures were established, and the culture conditions for the production of CADs were optimized. The hairy roots were induced by coculture of S. rebaudiana leaves and Agrobacterium rhizogenes (C58C1) after infection, which were further verified by PCR detection of rolB and rolC genes. HPLC-MS and HPLC analysis showed that chlorogenic acid (3-caffeoylquinic acid, 3-CQA), 3,5-dicaffeoylquinic acid (3,5-CQA), and 4,5-dicaffeoylquinic acid (4,5-CQA) were the major CADs in the hairy roots. Eight single roots with rapid growth rate were selected. Among them, T3 had the highest yield of CADs. B5 medium supplemented with 40 g/L sucrose was more suitable for the production of CADs than others. Under optimal culture conditions, the total content of these three compounds reached 105.58 mg/g and total yield was 234.40 mg/100 mL.

  1. The Effect of Humic Acid on Nutrient Composition in Broad Bean (Vicia faba L. Roots

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    Sener AKINCI

    2009-12-01

    Full Text Available Humic acids promote the conversion of mineral nutrients into forms available to plants. It also stimulates seed germination and viability, and its main effect usually being more prominent in the roots. The objective of this study was to determine of the influence of humic acid on broad bean (Vicia faba L. cultivar �Eresen 87� on root growth and development as well as nutrient uptake, during investigation in a pot experiment. Treatment with leonardite, as humic acid source positively affected both germination and harvesting, enhancing root length and biomass. Humic acid (HA caused significant increase of fresh (RFW and dry (RDW weights by 30.1% and 56.6% of broad bean roots, respectively. Flame photometer and atomic absorption spectrophotometry analyses revealed that K content was major nutrient among the tested elements. Humic acid increased the contents of Na and K significantly. The content of Ca and Fe was not significantly increased whereas Cu, Mn and Zn content decreased under HA treatment.

  2. ent-kaur-16-en-19-oic acid, isolated from the roots of Aralia continentalis, induces activation of Nrf2

    Science.gov (United States)

    Lyu, Ji-Hyo; Lee, Guem-San; Kim, Kyun-Ha; Kim, Hyung-Woo; Cho, Su-In; Jeong, Seung-Il; Kim, Hong-Jun; Ju, Young-Seung; Kim, Ho-Kyoung; Sadikot, Ruxana T.; Christman, John W.; Oh, Sei-Ryang; Lee, Hyeong-Kyu; Ahn, Kyung-Seop; Joo, Myungsoo

    2013-01-01

    Aim of the study Excessive inflammation can lead to tissue damage and dysfunction of vital organs. Hence, regulating inflammatory response is a viable therapeutic approach. In Asian countries, various inflammatory diseases have often effectively been treated with herbal remedies including the root extract of Aralia continentalis Kitagawa (Araliaceae). Here, we investigated the effect of kaurenoic acid (ent-kaur-16-en-19-oic acid: KA), a diterpenoid that is extracted from Aralia continentalis Kitagawa root, on inflammation. Results Western blot and RT-PCR analyses show that KA induced the nuclear localization of Nrf2 as low as 1 nM in concentration and that KA treatment induced the expression of Nrf2 dependent genes such as GCLC and HO-1. On the other hand, KA did not affect the degradation of cytoplasmic IκB-α, the nuclear localization of RelA (p65), and NF-κB transcriptional activity in RAW 264.7 cells treated with endotoxin. Consistent with these data, KA treatment failed to suppress gene expression of representative pro-inflammatory mediators including COX-2, nitric oxide, IL-1β, TNF-α, and IL-12, indicating that KA did not have an important impact on NF-κB activation. Conclusion Together, these results show that KA was an effective activator of Nrf2, and suggest that the beneficial effects of A. continentalis Kitagawa root extract are, at least in part, mediated by activating Nrf2. PMID:21884778

  3. Myxostiolide, myxostiol, and clavatoic acid, plant growth regulators from the fungus Myxotrichum stipitatum.

    Science.gov (United States)

    Kimura, Yasuo; Shimada, Atsumi; Kusano, Miyako; Yoshii, Katsunobu; Morita, Akiko; Nishibe, Masahiko; Fujioka, Shozo; Kawano, Tsuyoshi

    2002-04-01

    New plant growth regulators, named myxostiolide (1), myxostiol (2), and clavatoic acid (3), have been isolated from Myxotrichum stipitatum, and their structures have been established by spectroscopic methods including 2D NMR. The biological activities of 1, 2, and 3 have been examined using tea pollen and lettuce seedling bioassay methods. With tea pollen, compound 1 inhibited the pollen tube growth to 14% of control at a concentration of 100 mg/L. With lettuce seedlings, compound 2 accelerated the root growth from 1 mg/L to 100 mg/L and compound 3 inhibited the root growth, to 52% of control, at a concentration of 100 mg/L.

  4. Transcriptional profiling of Zea mays roots reveals roles for jasmonic acid and terpenoids in resistance against Phytophthora cinnamomi.

    Science.gov (United States)

    Allardyce, Jane Alisa; Rookes, James Edward; Hussain, Hashmath Inayath; Cahill, David Miles

    2013-06-01

    Phytophthora cinnamomi is a soil-borne plant pathogen that has caused widespread damage to vulnerable native ecosystems and agriculture systems across the world and shows no sign of abating. Management of the pathogen in the natural environment is difficult and the options are limited. In order to discover more about how resistant plants are able to defend themselves against this generalist pathogen, a microarray study of plant gene expression following root inoculation with P. cinnamomi was undertaken. Zea mays was used as a resistant model plant, and microarray analysis was conducted using the Affymetrix GeneChip Maize Genome Array on root samples collected at 6- and 24-h post-inoculation. Over 300 genes were differentially expressed in inoculated roots compared with controls across the two time points. Following Gene Ontology enrichment analysis and REVIGO visualisation of the up-regulated genes, many were implicated in plant defence responses to biotic stress. Genes that were up-regulated included those involved in phytoalexin biosynthesis and jasmonic acid/ethylene biosynthesis and other defence-related genes including those encoding glutathione S-transferases and serine-protease inhibitors. Of particular interest was the identification of the two most highly up-regulated genes, terpene synthase11 (Tps11) and kaurene synthase2 (An2), which are both involved in production of terpenoid phytoalexins. This is the first study that has investigated gene expression at a global level in roots in response to P. cinnamomi in a model plant species and provides valuable insights into the mechanisms involved in defence.

  5. Transcriptional and post-transcriptional regulation of a NAC1 transcription factor in Medicago truncatula roots.

    Science.gov (United States)

    D'haeseleer, Katrien; Den Herder, Griet; Laffont, Carole; Plet, Julie; Mortier, Virginie; Lelandais-Brière, Christine; De Bodt, Stefanie; De Keyser, Annick; Crespi, Martin; Holsters, Marcelle; Frugier, Florian; Goormachtig, Sofie

    2011-08-01

    • Legume roots develop two types of lateral organs, lateral roots and nodules. Nodules develop as a result of a symbiotic interaction with rhizobia and provide a niche for the bacteria to fix atmospheric nitrogen for the plant. • The Arabidopsis NAC1 transcription factor is involved in lateral root formation, and is regulated post-transcriptionally by miRNA164 and by SINAT5-dependent ubiquitination. We analyzed in Medicago truncatula the role of the closest NAC1 homolog in lateral root formation and in nodulation. • MtNAC1 shows a different expression pattern in response to auxin than its Arabidopsis homolog and no changes in lateral root number or nodulation were observed in plants affected in MtNAC1 expression. In addition, no interaction was found with SINA E3 ligases, suggesting that post-translational regulation of MtNAC1 does not occur in M. truncatula. Similar to what was found in Arabidopsis, a conserved miR164 target site was retrieved in MtNAC1, which reduced protein accumulation of a GFP-miR164 sensor. Furthermore, miR164 and MtNAC1 show an overlapping expression pattern in symbiotic nodules, and overexpression of this miRNA led to a reduction in nodule number. • This work suggests that regulatory pathways controlling a conserved transcription factor are complex and divergent between M. truncatula and Arabidopsis.

  6. EFFECTS OF GROWTH REGULATORS ON ROOTING CUTTINGS OF SYRINGA (PHILADELPHUS L.,PHILADELPHACEAE

    Directory of Open Access Journals (Sweden)

    Grekova I. V.

    2015-01-01

    Full Text Available Increased range of Syringa in landscaping is a topical issue. They are very decorative shrubs, more and more widely used in landscape design. Study of vegetative propagation of plants, with the use of growth regulators, was conducted to identify the most perspective stimulator and to reduce the terms of the finished product. Syringa refers to bad rooting cultures. However, the methods of green propagation of cuttings with the use of growth stimulators not only propagate a culture, but also increase the yield of landing products. The article considers the technology propagation by cuttings of this promising shrub. It also shows the effect of growth stimulators: radifarma and HB-101, used for soaking of cuttings. According to the research, we have found an apparent benefits effect of the processing of cuttings with the stimulators on growth and development of root system. The analysis of the tables of rooting rate of cuttings shows the positive development of cuttings in the processing of the growth regulators. We have obtained the experimental data allowing to define which varieties distinguished by the greatest rooting and duration rooting among all the studied cultivars. Thus, the studies show that the use of growth stimulators with propagation of Syringa cuttings is an effective way of reproduction

  7. Salicylic acid prevents Trichoderma harzianum from entering the vascular system of roots.

    Science.gov (United States)

    Alonso-Ramírez, Ana; Poveda, Jorge; Martín, Ignacio; Hermosa, Rosa; Monte, Enrique; Nicolás, Carlos

    2014-10-01

    Trichoderma is a soil-borne fungal genus that includes species with a significant impact on agriculture and industrial processes. Some Trichoderma strains exert beneficial effects in plants through root colonization, although little is known about how this interaction takes place. To better understand this process, the root colonization of wild-type Arabidopsis and the salicylic acid (SA)-impaired mutant sid2 by a green fluorescent protein (GFP)-marked Trichoderma harzianum strain was followed under confocal microscopy. Trichoderma harzianum GFP22 was able to penetrate the vascular tissue of the sid2 mutant because of the absence of callose deposition in the cell wall of root cells. In addition, a higher colonization of sid2 roots by GFP22 compared with that in Arabidopsis wild-type roots was detected by real-time polymerase chain reaction. These results, together with differences in the expression levels of plant defence genes in the roots of both interactions, support a key role for SA in Trichoderma early root colonization stages. We observed that, without the support of SA, plants were unable to prevent the arrival of the fungus in the vascular system and its spread into aerial parts, leading to later collapse.

  8. Ion Release, Microstructural, and Biological Properties of iRoot BP Plus and ProRoot MTA Exposed to an Acidic Environment.

    Science.gov (United States)

    Tian, Jun; Zhang, Yuanhe; Lai, Zhihui; Li, Mengjie; Huang, Yu; Jiang, Hongwei; Wei, Xi

    2017-01-01

    This study evaluated how exposing the novel calcium silicate nanoparticulate bioceramic iRoot BP Plus (Innovative Bioceramix, Vancouver, Canada) to an acidic environment affects ion release from this material and alters MC3T3-E1 preosteoblast viability on and attachment to this material. These factors were compared against those of ProRoot MTA under similar conditions. Each material was exposed to phosphate-buffered saline (pH = 7.4) or butyric acid (pH = 5.4) for 5 days. Trace metal elements within the 2 materials and released ions were identified using inductively coupled plasma optical emission spectroscopy. The microstructures and elemental compositions of MTA and iRoot BP Plus after treatment with butyric acid were determined using scanning electron microscopy with an energy-dispersive X-ray spectrometer. Furthermore, the viability of MC3T3-E1 cells on and their levels of attachment to the materials after the butyric acid treatment were compared. iRoot BP Plus contained fewer toxic metal elements than MTA. Under acidic conditions, both materials displayed similar ion release abilities, with increased release of Si and Ca ions. Substantial changes in microstructure, including reduced apatite formation, were observed for both materials after exposure to acidic pH. Furthermore, exposing iRoot BP Plus and MTA to an acidic environment increased and decreased MC3T3-E1 cell viability on these materials, respectively. MC3T3-E1 cell attachment to both materials was not significantly affected by acidic pH. iRoot BP Plus seems more biologically appropriate for application in an inflamed acidic environment than ProRoot MTA. Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

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

    Science.gov (United States)

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

    1984-01-01

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

  10. Effects and mechanisms of the combined pollution of lanthanum and acid rain on the root phenotype of soybean seedlings.

    Science.gov (United States)

    Sun, Zhaoguo; Wang, Lihong; Zhou, Qing; Huang, Xiaohua

    2013-09-01

    Rare earth pollution and acid rain pollution are both important environmental issues worldwide. In regions which simultaneously occur, the combined pollution of rare earth and acid rain becomes a new environmental issue, and the relevant research is rarely reported. Accordingly, we investigated the combined effects and mechanisms of lanthanum ion (La(3+)) and acid rain on the root phenotype of soybean seedlings. The combined pollution of low-concentration La(3+) and acid rain exerted deleterious effects on the phenotype and growth of roots, which were aggravated by the combined pollution of high-concentration La(3+) and acid rain. The deleterious effects of the combined pollution were stronger than those of single La(3+) or acid rain pollution. These stronger deleterious effects on the root phenotype and growth of roots were due to the increased disturbance of absorption and utilization of mineral nutrients in roots.

  11. Organic acid metabolism and root excretion of malate in wheat cultivars under aluminium stress.

    Science.gov (United States)

    de Andrade, Leide Rovênia Miranda; Ikeda, Motoki; do Amaral, Lourdes Isabel Velho; Ishizuka, Junji

    2011-01-01

    The effects of aluminium (Al) on the metabolism of organic acids synthesised via nonphotosynthetic carbon fixation in the roots and on malate exudation were investigated in Al-tolerant Shirosanjyaku (SH) and Al-sensitive Chikushikomugi (CK) wheat cultivars labelled with bicarbonate-(14)C. Aluminum triggered the excretion of (14)C into the solution, especially in the SH that excreted 2.5 times more (14)C than the CK. The loss of radioactivity (about 10%) into the solution represented a small drain in the (14)C reserve found in the roots. In the organic acid fraction within the roots, malate contained the greatest amount of (14)C, and this amount decreased rapidly with time in both cultivars. The disappearance of radioactivity in the malate resulted from metabolism and translocation rather than to root efflux. Aluminium decreased the malate concentrations in roots of both cultivars. The Al-sensitive cultivar had higher concentrations of malate regardless of the presence of Al. It was therefore assumed that the decrease of malate concentration in roots under Al stress did not result from the decline in malate synthesis but due to an increase in malate decomposition. This response was interpreted as the result of the Al-induced stress and not as the cause of a differential Al-tolerance between the wheat cultivars. An important component of the differential Al tolerance between SH and CK is the greater ability of the Al-tolerant cultivar to excrete malate from the roots, which is independent of its internal concentration in the roots.

  12. A Potassium-Dependent Oxygen Sensing Pathway Regulates Plant Root Hydraulics.

    Science.gov (United States)

    Shahzad, Zaigham; Canut, Matthieu; Tournaire-Roux, Colette; Martinière, Alexandre; Boursiac, Yann; Loudet, Olivier; Maurel, Christophe

    2016-09-22

    Aerobic organisms survive low oxygen (O2) through activation of diverse molecular, metabolic, and physiological responses. In most plants, root water permeability (in other words, hydraulic conductivity, Lpr) is downregulated under O2 deficiency. Here, we used a quantitative genetics approach in Arabidopsis to clone Hydraulic Conductivity of Root 1 (HCR1), a Raf-like MAPKKK that negatively controls Lpr. HCR1 accumulates and is functional under combined O2 limitation and potassium (K(+)) sufficiency. HCR1 regulates Lpr and hypoxia responsive genes, through the control of RAP2.12, a key transcriptional regulator of the core anaerobic response. A substantial variation of HCR1 in regulating Lpr is observed at the Arabidopsis species level. Thus, by combinatorially integrating two soil signals, K(+) and O2 availability, HCR1 modulates the resilience of plants to multiple flooding scenarios.

  13. Spatial Regulation of Root Growth: Placing the Plant TOR Pathway in a Developmental Perspective

    Directory of Open Access Journals (Sweden)

    Adam Barrada

    2015-08-01

    Full Text Available Plant cells contain specialized structures, such as a cell wall and a large vacuole, which play a major role in cell growth. Roots follow an organized pattern of development, making them the organs of choice for studying the spatio-temporal regulation of cell proliferation and growth in plants. During root growth, cells originate from the initials surrounding the quiescent center, proliferate in the division zone of the meristem, and then increase in length in the elongation zone, reaching their final size and differentiation stage in the mature zone. Phytohormones, especially auxins and cytokinins, control the dynamic balance between cell division and differentiation and therefore organ size. Plant growth is also regulated by metabolites and nutrients, such as the sugars produced by photosynthesis or nitrate assimilated from the soil. Recent literature has shown that the conserved eukaryotic TOR (target of rapamycin kinase pathway plays an important role in orchestrating plant growth. We will summarize how the regulation of cell proliferation and cell expansion by phytohormones are at the heart of root growth and then discuss recent data indicating that the TOR pathway integrates hormonal and nutritive signals to orchestrate root growth.

  14. Spatial Regulation of Root Growth: Placing the Plant TOR Pathway in a Developmental Perspective

    Science.gov (United States)

    Barrada, Adam; Montané, Marie-Hélène; Robaglia, Christophe; Menand, Benoît

    2015-01-01

    Plant cells contain specialized structures, such as a cell wall and a large vacuole, which play a major role in cell growth. Roots follow an organized pattern of development, making them the organs of choice for studying the spatio-temporal regulation of cell proliferation and growth in plants. During root growth, cells originate from the initials surrounding the quiescent center, proliferate in the division zone of the meristem, and then increase in length in the elongation zone, reaching their final size and differentiation stage in the mature zone. Phytohormones, especially auxins and cytokinins, control the dynamic balance between cell division and differentiation and therefore organ size. Plant growth is also regulated by metabolites and nutrients, such as the sugars produced by photosynthesis or nitrate assimilated from the soil. Recent literature has shown that the conserved eukaryotic TOR (target of rapamycin) kinase pathway plays an important role in orchestrating plant growth. We will summarize how the regulation of cell proliferation and cell expansion by phytohormones are at the heart of root growth and then discuss recent data indicating that the TOR pathway integrates hormonal and nutritive signals to orchestrate root growth. PMID:26295391

  15. Spatial Regulation of Root Growth: Placing the Plant TOR Pathway in a Developmental Perspective.

    Science.gov (United States)

    Barrada, Adam; Montané, Marie-Hélène; Robaglia, Christophe; Menand, Benoît

    2015-08-19

    Plant cells contain specialized structures, such as a cell wall and a large vacuole, which play a major role in cell growth. Roots follow an organized pattern of development, making them the organs of choice for studying the spatio-temporal regulation of cell proliferation and growth in plants. During root growth, cells originate from the initials surrounding the quiescent center, proliferate in the division zone of the meristem, and then increase in length in the elongation zone, reaching their final size and differentiation stage in the mature zone. Phytohormones, especially auxins and cytokinins, control the dynamic balance between cell division and differentiation and therefore organ size. Plant growth is also regulated by metabolites and nutrients, such as the sugars produced by photosynthesis or nitrate assimilated from the soil. Recent literature has shown that the conserved eukaryotic TOR (target of rapamycin) kinase pathway plays an important role in orchestrating plant growth. We will summarize how the regulation of cell proliferation and cell expansion by phytohormones are at the heart of root growth and then discuss recent data indicating that the TOR pathway integrates hormonal and nutritive signals to orchestrate root growth.

  16. Root uptake and translocation of perfluorinated alkyl acids by three hydroponically grown crops

    NARCIS (Netherlands)

    Felizeter, S.; McLachlan, M.S.; de Voogt, P.

    2014-01-01

    Tomato, cabbage, and zucchini plants were grown hydroponically in a greenhouse. They were exposed to 14 perfluorinated alkyl acids (PFAAs) at four different concentrations via the nutrient solution. At maturity the plants were harvested, and the roots, stems, leaves, twigs (where applicable), and ed

  17. Valve-regulated lead-acid batteries

    Science.gov (United States)

    Berndt, D.

    Valve-regulated lead-acid (VRLA) batteries with gelled electrolyte appeared as a niche market during the 1950s. During the 1970s, when glass-fiber felts became available as a further method to immobilize the electrolyte, the market for VRLA batteries expanded rapidly. The immobilized electrolyte offers a number of obvious advantages including the internal oxygen cycle which accommodates the overcharging current without chemical change within the cell. It also suppresses acid stratification and thus opens new fields of application. VRLA batteries, however, cannot be made completely sealed, but require a valve for gas escape, since hydrogen evolution and grid corrosion are unavoidable secondary reactions. These reactions result in water loss, and also must be balanced in order to ensure proper charging of both electrodes. Both secondary reactions have significant activation energies, and can reduce the service life of VRLA batteries, operated at elevated temperature. This effect can be aggravated by the comparatively high heat generation caused by the internal oxygen cycle during overcharging. Temperature control of VRLA batteries, therefore, is important in many applications.

  18. Regulation of root morphogenesis in arbuscular mycorrhizae: what role do fungal exudates, phosphate, sugars and hormones play in lateral root formation?

    Science.gov (United States)

    Fusconi, Anna

    2014-01-01

    Arbuscular mycorrhizae (AMs) form a widespread root-fungus symbiosis that improves plant phosphate (Pi) acquisition and modifies the physiology and development of host plants. Increased branching is recognized as a general feature of AM roots, and has been interpreted as a means of increasing suitable sites for colonization. Fungal exudates, which are involved in the dialogue between AM fungi and their host during the pre-colonization phase, play a well-documented role in lateral root (LR) formation. In addition, the increased Pi content of AM plants, in relation to Pi-starved controls, as well as changes in the delivery of carbohydrates to the roots and modulation of phytohormone concentration, transport and sensitivity, are probably involved in increasing root system branching. This review discusses the possible causes of increased branching in AM plants. The differential root responses to Pi, sugars and hormones of potential AM host species are also highlighted and discussed in comparison with those of the non-host Arabidopsis thaliana. Fungal exudates are probably the main compounds regulating AM root morphogenesis during the first colonization steps, while a complex network of interactions governs root development in established AMs. Colonization and high Pi act synergistically to increase root branching, and sugar transport towards the arbusculated cells may contribute to LR formation. In addition, AM colonization and high Pi generally increase auxin and cytokinin and decrease ethylene and strigolactone levels. With the exception of cytokinins, which seem to regulate mainly the root:shoot biomass ratio, these hormones play a leading role in governing root morphogenesis, with strigolactones and ethylene blocking LR formation in the non-colonized, Pi-starved plants, and auxin inducing them in colonized plants, or in plants grown under high Pi conditions.

  19. [Effect of lectins from Azospirillum brasilense to peroxidase and oxalate oxidase activity regulation in wheat roots].

    Science.gov (United States)

    Alen'kina, S A; Nikitina, V E

    2010-01-01

    Lectins were extracted from the surface of nitrogen-fixing soil bacteria Azospirillum brasilense Sp7 and from its mutant A. brasilense Sp7.2.3 defective in lectin activity. The ability oflectins to stimulate the rapid formation of hydrogen peroxide related to increase of oxalate oxidase and peroxidase activity in the roots of wheat seedlings has been demonstrated. The most rapid induced pathway of hydrogen peroxide formation in the roots of wheat seedlings was the oxalic acid oxidation by oxalate oxidase which is the effect oflectin in under 10 min in a concentration of 10 microg/ml. The obtained results show that lectins from Azospirillum are capable of inducing the adaptation processes in the roots of wheat seedlings.

  20. Effects of silicon on Oryza sativa L. seedling roots under simulated acid rain stress.

    Science.gov (United States)

    Ju, Shuming; Yin, Ningning; Wang, Liping; Zhang, Cuiying; Wang, Yukun

    2017-01-01

    Silicon (Si) has an important function in reducing the damage of environmental stress on plants. Acid rain is a serious abiotic stress factor, and Si can alleviate the stress induced by acid rain on plants. Based on these assumptions, we investigated the effects of silicon on the growth, root phenotype, mineral element contents, hydrogen peroxide (H2O2) and antioxidative enzymes of rice (Oryza sativa L.) seedling roots under simulated acid rain (SAR) stress. The results showed that the combined or single effects of Si and/or SAR on rice roots depend on the concentration of Si and the pH of the SAR. The combined or single effects of a low or moderate concentration of Si (1.0 or 2.0 mM) and light SAR (pH 4.0) enhanced the growth of rice roots, and the combined effects were stronger than those of the single treatment. A high concentration of Si (4.0 mM) or severe SAR (pH 2.0) exerted deleterious effects. The incorporation of Si (1.0, 2.0 or 4.0 mM) into SAR with pH 3.0 or 2.0 promoted the rice root growth, decreased the H2O2 content, increased the Si concentration and the superoxide dismutase (SOD), catalase (CAT), peroxidase (POD) and ascorbate peroxidase (APX) activities, maintained the balance of mineral element (K, Ca, Mg, Fe, Zn, and Cu) concentrations in the roots of rice seedlings compared with SAR alone. The alleviatory effects observed with a moderate concentration of Si (2.0 mM) were better than the effects obtained with a low or high concentration of Si (1.0 or 4.0 mM). The observed effects were due to disruptions in the absorption and utilization of mineral nutrients and impacts on the activity of antioxidant enzymes in roots, and this conclusion suggests that the degree of rice root damage caused by acid rain might be attributed to not only acid rain but also the level of Si in the soil.

  1. 2,4-dichlorophenoxyacetic acid as an alternative auxin for rooting of vine rootstock cuttings

    Directory of Open Access Journals (Sweden)

    Mauro Brasil Dias Tofanelli

    2014-09-01

    Full Text Available Viticulture is an important agricultural activity in semiarid northeastern Brazil, and the quality and ease of vine propagation are very important in this context. This study evaluated the use of 2,4-dichlorophenoxyacetic acid (2,4-D as an alternative to indolebutyric acid (IBA in the rooting of vine rootstock cuttings. The trial was conducted at the Universidade Federal de Sergipe (São Cristóvão-SE between January and March 2010 with cuttings of the rootstocks of 'IAC-766', 'IAC-572', and 'Paulsen 1103' treated with 2,4-D or IBA applied at concentrations of 0, 1000, 2000, or 3000 rng-L-1 for 5 s and planted in a field on washed sand. At 56 days after planting, the percentages of rooted, sprouted, callused, and dead cuttings were evaluated, and also the average number and length of the rooted cuttings. The results showed that 2,4-D was not superior to IBA in the characteristics wanted for the rooting process of the vine rootstock cuttings. The vine rootstocks showed potential for propagation by cutting without auxin application. It was observed that the high concentrations were the worst for the rooting of the cuttings.

  2. Acidomelania panicicola gen. et sp. nov. from switchgrass roots in acidic New Jersey pine barrens.

    Science.gov (United States)

    Walsh, Emily; Luo, Jing; Zhang, Ning

    2014-01-01

    A new genus, Acidomelania, is described based on molecular phylogenetic analyses and ecological and morphological characters. Isolated from switchgrass roots in acidic and oligotrophic New Jersey pine barrens in this study, Acidomelania likely has a global distribution because its internal transcribed spacer (ITS) sequence has high similarity with a number of GenBank sequences resulted from various ecological studies. Apparently these samples all were from roots of plants that lived in acidic, nutrient-poor environments. Phylogenetic analyses based on ITS, LSU and ACT sequence data strongly supported the fact that Acidomelania isolates formed a monophyletic clade in Helotiales, distinct from any known taxa. Phylogenetically Acidomelania is closely related to Loramyces, Mollisia and Phialocephala fortinii, Acephala applanata species complex (PAC), the dark septate endophytes. Acidomelania also can be distinguished from Loramyces and Mollisia by its association with living grass roots. While taxa in PAC also are root endophytes, they have more complex phialid arrangement than Acidomelania. Results from this work will facilitate ecological and evolutionary studies on root-associated fungi.

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

    Institute of Scientific and Technical Information of China (English)

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

    2005-01-01

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

  4. Transcriptional profiling of sweetpotato (Ipomoea batatas) roots indicates down-regulation of lignin biosynthesis and up-regulation of starch biosynthesis at an early stage of storage root formation

    Science.gov (United States)

    2013-01-01

    Background The number of fibrous roots that develop into storage roots determines sweetpotato yield. The aim of the present study was to identify the molecular mechanisms involved in the initiation of storage root formation, by performing a detailed transcriptomic analysis of initiating storage roots using next-generation sequencing platforms. A two-step approach was undertaken: (1) generating a database for the sweetpotato root transcriptome using 454-Roche sequencing of a cDNA library created from pooled samples of two root types: fibrous and initiating storage roots; (2) comparing the expression profiles of initiating storage roots and fibrous roots, using the Illumina Genome Analyzer to sequence cDNA libraries of the two root types and map the data onto the root transcriptome database. Results Use of the 454-Roche platform generated a total of 524,607 reads, 85.6% of which were clustered into 55,296 contigs that matched 40,278 known genes. The reads, generated by the Illumina Genome Analyzer, were found to map to 31,284 contigs out of the 55,296 contigs serving as the database. A total of 8,353 contigs were found to exhibit differential expression between the two root types (at least 2.5-fold change). The Illumina-based differential expression results were validated for nine putative genes using quantitative real-time PCR. The differential expression profiles indicated down-regulation of classical root functions, such as transport, as well as down-regulation of lignin biosynthesis in initiating storage roots, and up-regulation of carbohydrate metabolism and starch biosynthesis. In addition, data indicated delicate control of regulators of meristematic tissue identity and maintenance, associated with the initiation of storage root formation. Conclusions This study adds a valuable resource of sweetpotato root transcript sequences to available data, facilitating the identification of genes of interest. This resource enabled us to identify genes that are involved

  5. Progesterone produces antinociceptive and neuroprotective effects in rats with microinjected lysophosphatidic acid in the trigeminal nerve root

    Directory of Open Access Journals (Sweden)

    Kim Min

    2012-03-01

    Full Text Available Abstract Background In our present study, we studied the role of demyelination of the trigeminal nerve root in the development of prolonged nociceptive behavior in the trigeminal territory. Results Under anesthesia, the Sprague-Dawley rats were mounted onto a stereotaxic frame and 3 μL of lysophosphatidic acid (LPA, 1 nmol was injected into the trigeminal nerve root to produce demyelination. This treatment decreased the air-puff thresholds, persisted until postoperative day 130, and then returned to the preoperative levels 160 days after LPA injection. The LPA-treated rats also showed a significant hyper-responsiveness to pin-prick stimulation. We further investigated the antinociceptive and neuroprotective effects of progesterone in rats undergoing demyelination of the trigeminal nerve root. Progesterone (8, 16 mg/kg/day was administered subcutaneously, beginning on the operative day, for five consecutive days in the LPA-treated rats. Treatment with progesterone produced significant early anti-allodynic effects and delayed prolonged anti-allodynic effects. The expression of protein zero (P0 and peripheral myelin protein 22 (PMP22 were significantly down-regulated in the trigeminal nerve root on postoperative day 5 following LPA injection. This down-regulation of the P0 and PMP22 levels was blocked by progesterone treatment. Conclusions These results suggest that progesterone produces antinociceptive effects through neuroprotective action in animals with LPA-induced trigeminal neuropathic pain. Moreover, progesterone has potential utility as a novel therapy for trigeminal neuropathic pain relief at an appropriate managed dose and is therefore a possible future treatment strategy for improving the recovery from injury.

  6. Effect of Soil Moisture on Release of Low-MolecularWeight Organic Acids in Root Exudates and the Accumulation of Iron in Root Apoplasm of Peanut

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A three-compartments rhizobox was designed and used to study the low-molecular-weight organic acids in root exudates and the root apoplastic iron of "lime-induced chlorosis" peanut grown on a calcareous soil in relation to different soil moisture conditions. Results showed that chlorosis of peanuts developed under condition of high soil moisture level (250 g kg-1), while peanuts grew well and chlorosis did not develop when soil moisture was managed to a normal level (150 g kg-1). The malic acid, maleic acid and succinic acid contents of chlorotic peanut increased by 108.723, 0.029 and 22.446μg cm-2, respectively,compared with healthy peanuts. The content of citric acid and fumaric acid also increased in root exudates of chlorotic peanuts. On Days 28 and 42 of peanut growth, the accumulation of root apoplastic iron in chlorotic peanuts was higher than that of healthy peanuts. From Day 28 to Day 42, the mobilization percentages of chlorotic peanuts and healthy peanuts to root apoplastic iron were almost the same, being 52.4% and 52.8%,respectively, indicating that the chlorosis might be caused by the inactivation of iron within peanut plant grown on a calcareous soil under high soil moisture conditions.

  7. Dynamics of phenolic acids and lignin accumulation in metal-treated Matricaria chamomilla roots.

    Science.gov (United States)

    Kovácik, Jozef; Klejdus, Borivoj

    2008-03-01

    Phenylalanine ammonia-lyase (PAL) activity, 11 phenolic acids and lignin accumulation in Matricaria chamomilla roots exposed to low (3 microM) and high (60 and 120 microM) levels of cadmium (Cd) or copper (Cu) for 7 days were investigated. Five derivatives of cinnamic acid (chlorogenic, p-coumaric, caffeic, ferulic and sinapic acids) and six derivatives of benzoic acid (protocatechuic, vanillic, syringic, p-hydroxybenzoic, salicylic acids and protocatechuic aldehyde) were detected. Accumulation of glycoside-bound phenolics (revealed by acid hydrolysis) was enhanced mainly towards the end of the experiment, being more expressive in Cu-treated roots. Interestingly, chlorogenic acid was extremely elevated by the highest Cu dose (21-fold higher than control) suggesting its involvement in antioxidative protection. All compounds, with the exception of chlorogenic acid, were detected in the cell wall bound fraction, but only benzoic acids were found in the ester-bound fraction (revealed by alkaline hydrolysis). Soluble phenolics were present in substantially higher amounts in Cu-treated roots and more Cu was retained there in comparison to Cd. Cu strongly elevated PAL activity (by 5.4- and 12.1-fold in 60 and 120 microM treatment, respectively) and lignin content (by 71 and 148%, respectively) after one day of treatment, indicating formation of a barrier against metal entrance. Cd had slighter effects, supporting its non-redox active properties. Taken together, different forms of phenolic metabolites play an important role in chamomile tolerance to metal excess and participate in active antioxidative protection.

  8. TRIPTYCHON, not CAPRICE, participates in feedback regulation of SCM expression in the Arabidopsis root epidermis.

    Science.gov (United States)

    Kwak, Su-Hwan; Schiefelbein, John

    2014-01-01

    The Arabidopsis root epidermal cells decide their fates (root-hair cell and non-hair cell) according to their position. SCRAMBLED (SCM), an atypical leucine-rich repeat receptor-like kinase (LRR RLK) mediates the positional information to the epidermal cells enabling them to adopt the proper fate. Via feedback regulation, the SCM protein accumulates preferentially in cells adopting the root-hair cell fate. In this study, we determine that TRY, but not the related factor CPC, is responsible for this preferential SCM accumulation. We observed severe reduction of SCM::GUS expression in the try-82 mutant root, but not in the cpc-1 mutant. Furthermore, the overexpression of TRY by CaMV35S promoter caused an increase in the expression of SCM::GUS in the root epidermis. Intriguingly, the overexpression of CPC by CaMV35S promoter repressed the expression of SCM::GUS. Together, these results suggest that TRY plays a unique role in generating the appropriate spatial expression of SCM.

  9. Determination of Organic Acids in Root Exudates by High Performance Liquid Chromatography:Ⅲ.Effects of Interfering Factors

    Institute of Scientific and Technical Information of China (English)

    SHENJIANBO; ZHANGFUSUO; 等

    1999-01-01

    A solution culture experiment was conducted to investigate the effects of collection time and interfering ions on separation and determination of low-molecular-weight organic acids in root exudates of soybean using the method for directly collecting root exudates.The suitable cooection time of root exudates and the interferiung ions affecting organic acid determination were determined.The method for removing the interfering ions was established and analyzed.The release amount of root exudates increased with the increase of collection time from 0 to 120min but decreased with increasing of collection time from 120to 240min.The maximum exuding amounts of organic acids were observed in root exudates at the collection time of 120min.There was a significant difference of organic acid components between the treatments of collection time of 120min and 240min,Citric acid was founnd only in the treatment of 120min collection time,NO3- was the main interfering ion in organic acid determination and had the same retention time as oxalic acid.Anion exchange resin(SAX)properly treated by HPLC(high performance liquid chromatography)solvent could remove NO3- anion in sample solution of root exudates,thus enhancing the recoveries of organic acids in root exudates.There was no significant effect of the chemicals added into sample solution such as H3PO4,SAX and KNO3 on the retention time of organic acids.

  10. Sequential induction of auxin efflux and influx carriers regulates lateral root emergence.

    Science.gov (United States)

    Péret, Benjamin; Middleton, Alistair M; French, Andrew P; Larrieu, Antoine; Bishopp, Anthony; Njo, Maria; Wells, Darren M; Porco, Silvana; Mellor, Nathan; Band, Leah R; Casimiro, Ilda; Kleine-Vehn, Jürgen; Vanneste, Steffen; Sairanen, Ilkka; Mallet, Romain; Sandberg, Göran; Ljung, Karin; Beeckman, Tom; Benkova, Eva; Friml, Jiří; Kramer, Eric; King, John R; De Smet, Ive; Pridmore, Tony; Owen, Markus; Bennett, Malcolm J

    2013-10-22

    In Arabidopsis, lateral roots originate from pericycle cells deep within the primary root. New lateral root primordia (LRP) have to emerge through several overlaying tissues. Here, we report that auxin produced in new LRP is transported towards the outer tissues where it triggers cell separation by inducing both the auxin influx carrier LAX3 and cell-wall enzymes. LAX3 is expressed in just two cell files overlaying new LRP. To understand how this striking pattern of LAX3 expression is regulated, we developed a mathematical model that captures the network regulating its expression and auxin transport within realistic three-dimensional cell and tissue geometries. Our model revealed that, for the LAX3 spatial expression to be robust to natural variations in root tissue geometry, an efflux carrier is required--later identified to be PIN3. To prevent LAX3 from being transiently expressed in multiple cell files, PIN3 and LAX3 must be induced consecutively, which we later demonstrated to be the case. Our study exemplifies how mathematical models can be used to direct experiments to elucidate complex developmental processes.

  11. Transcription factor WRKY46 modulates the development of Arabidopsis lateral roots in osmotic/salt stress conditions via regulation of ABA signaling and auxin homeostasis.

    Science.gov (United States)

    Ding, Zhong Jie; Yan, Jing Ying; Li, Chun Xiao; Li, Gui Xin; Wu, Yun Rong; Zheng, Shao Jian

    2015-10-01

    The development of lateral roots (LR) is known to be severely inhibited by salt or osmotic stress. However, the molecular mechanisms underlying LR development in osmotic/salt stress conditions are poorly understood. Here we show that the gene encoding the WRKY transcription factor WRKY46 (WRKY46) is expressed throughout lateral root primordia (LRP) during early LR development and that expression is subsequently restricted to the stele of the mature LR. In osmotic/salt stress conditions, lack of WRKY46 (in loss-of-function wrky46 mutants) significantly reduces, while overexpression of WRKY46 enhances, LR development. We also show that exogenous auxin largely restores LR development in wrky46 mutants, and that the auxin transport inhibitor 2,3,5-triiodobenzoic acid (TIBA) inhibits LR development in both wild-type (WT; Col-0) and in a line overexpressing WRKY46 (OV46). Subsequent analysis of abscisic acid (ABA)-related mutants indicated that WRKY46 expression is down-regulated by ABA signaling, and up-regulated by an ABA-independent signal induced by osmotic/salt stress. Next, we show that expression of the DR5:GUS auxin response reporter is reduced in roots of wrky46 mutants, and that both wrky46 mutants and OV46 display altered root levels of free indole-3-acetic acid (IAA) and IAA conjugates. Subsequent RT-qPCR and ChIP-qPCR experiments indicated that WRKY46 directly regulates the expression of ABI4 and of genes regulating auxin conjugation. Finally, analysis of wrky46 abi4 double mutant plants confirms that ABI4 acts downstream of WRKY46. In summary, our results demonstrate that WRKY46 contributes to the feedforward inhibition of osmotic/salt stress-dependent LR inhibition via regulation of ABA signaling and auxin homeostasis.

  12. The regulation of electron partitioning between the cytochrome and alternative pathways in soybean cotyledon and root mitochondria

    Energy Technology Data Exchange (ETDEWEB)

    Ribas-Carbo, M.; Lennon, A.M.; Robinson, S.A. [Duke Univ., Durham, NC (United States)] [and others

    1997-03-01

    The regulation of electron partitioning between the cytochrome (Cyt) and alternative pathways in soybean (Glycine max L. cv Ransom) mitochondria in the absence of added inhibitors has been studied using the oxygen isotope fractionation technique. This regulation can depend on several factors, including the amount of alternative oxidase protein, the redox status of the alternative oxidase regulatory sulfhydryl-disulfide system, the degree of activation by {alpha}-keto acids, and the concentration and redox state of the ubiquinone pool. We studied electron partitioning onto the alternative pathway in mitochondria isolated from etiolated and light-grown cotyledons and roots to ascertain how these factors interact in different tissues. In light-grown cotyledon mitochondria there is some partitioning to the alternative pathway in state 4, which is increased dramatically by either pyruvate or dithiothreitol. In etiolated cotyledon mitochondria, the alternative pathway shows little ability to complete for electrons with the Cyt pathway under any circumstances. In root mitochondria, control of alternative pathway activity is exercised by both the ubiquinone pool and the regulatory sulfhydryl-disulfide system. In addition, oxygen isotope fractionation by the Cyt and alternative pathways in mitochondria were identical to the fractionation for the respective pathways seen in intact tissue, suggesting that residual respiration is not present in the absence of inhibitors. 38 refs., 3 figs., 2 tabs.

  13. Enhancement of Chlorogenic Acid Production in Hairy Roots of Platycodon grandiflorum by Over-Expression of An Arabidopsis thaliana Transcription Factor AtPAP1

    Directory of Open Access Journals (Sweden)

    Pham Anh Tuan

    2014-08-01

    Full Text Available To improve the production of chlorogenic acid (CGA in hairy roots of Platycodon grandiflorum, we induced over-expression of Arabidopsis thaliana transcription factor production of anthocyanin pigment (AtPAP1 using an Agrobacterium rhizogenes-mediated transformation system. Twelve hairy root lines showing over-expression of AtPAP1 were generated. In order to investigate the regulation of AtPAP1 on the activities of CGA biosynthetic genes, the expression levels of seven P. grandiflorum CGA biosynthetic genes were analyzed in the hairy root line that had the greatest accumulation of AtPAP1 transcript, OxPAP1-1. The introduction of AtPAP1 increased the mRNA levels of all examined CGA biosynthetic genes and resulted in a 900% up-regulation of CGA accumulation in OxPAP1-1 hairy roots relative to controls. This suggests that P. grandiflorum hairy roots that over-express the AtPAP1 gene are a potential alternative source of roots for the production of CGA.

  14. Enhancement of chlorogenic acid production in hairy roots of Platycodon grandiflorum by over-expression of an Arabidopsis thaliana transcription factor AtPAP1.

    Science.gov (United States)

    Tuan, Pham Anh; Kwon, Do Yeon; Lee, Sanghyun; Arasu, Mariadhas Valan; Al-Dhabi, Naif Abdullah; Park, Nam Il; Park, Sang Un

    2014-08-22

    To improve the production of chlorogenic acid (CGA) in hairy roots of Platycodon grandiflorum, we induced over-expression of Arabidopsis thaliana transcription factor production of anthocyanin pigment (AtPAP1) using an Agrobacterium rhizogenes-mediated transformation system. Twelve hairy root lines showing over-expression of AtPAP1 were generated. In order to investigate the regulation of AtPAP1 on the activities of CGA biosynthetic genes, the expression levels of seven P. grandiflorum CGA biosynthetic genes were analyzed in the hairy root line that had the greatest accumulation of AtPAP1 transcript, OxPAP1-1. The introduction of AtPAP1 increased the mRNA levels of all examined CGA biosynthetic genes and resulted in a 900% up-regulation of CGA accumulation in OxPAP1-1 hairy roots relative to controls. This suggests that P. grandiflorum hairy roots that over-express the AtPAP1 gene are a potential alternative source of roots for the production of CGA.

  15. Down-regulation of defense genes and resource allocation into infected roots as factors for compatibility between Fagus sylvatica and Phytophthora citricola.

    Science.gov (United States)

    Schlink, Katja

    2010-05-01

    Phytophthora citricola is a wide spread and highly aggressive pathogen of Fagus sylvatica. The hemibiotrophic oomycete infects the roots and establishes a compatible interaction with F. sylvatica. To investigate the transcriptional changes associated with P. citricola infection, 68 custom oligo-microarray measurements were conducted. Hierarchical as well as non-hierarchical clustering was carried out to analyze the expression profiles. Experimental setup includes a time scale covering the biotrophic and necrotrophic stages of interaction as well as comparative analyses of the local and systemic responses. The local reaction of F. sylvatica is characterized by a striking lack of defense gene induction leading to the conclusion that P. citricola escapes the main recognition systems and/or suppresses the host's response. The analysis of the systemic reaction revealed a massive shift in gene expression patterns during the biotrophic phase that is interpreted as evidence of resource allocation into the roots to support the increased sink caused by pathogen growth. Defense genes known to be responsive to salicylic acid (effective against biotrophs), jasmonic acid, and ethylene (effective against necrotrophs and herbivores) are represented on the arrays. All significant changes in gene expression measured for salicylic acid responsive genes were down-regulations in roots and leaves while some jasmonic acid responsive genes showed a very late up-regulation only in leaves, probably caused by the desiccation shortly before plant death. Together, these expression changes could explain the success of the pathogen.

  16. Inference of the Genetic Network Regulating Lateral Root Initiation in Arabidopsis thaliana

    KAUST Repository

    Muraro, D.

    2013-01-01

    Regulation of gene expression is crucial for organism growth, and it is one of the challenges in systems biology to reconstruct the underlying regulatory biological networks from transcriptomic data. The formation of lateral roots in Arabidopsis thaliana is stimulated by a cascade of regulators of which only the interactions of its initial elements have been identified. Using simulated gene expression data with known network topology, we compare the performance of inference algorithms, based on different approaches, for which ready-to-use software is available. We show that their performance improves with the network size and the inclusion of mutants. We then analyze two sets of genes, whose activity is likely to be relevant to lateral root initiation in Arabidopsis, and assess causality of their regulatory interactions by integrating sequence analysis with the intersection of the results of the best performing methods on time series and mutants. The methods applied capture known interactions between genes that are candidate regulators at early stages of development. The network inferred from genes significantly expressed during lateral root formation exhibits distinct scale free, small world and hierarchical properties and the nodes with a high out-degree may warrant further investigation. © 2004-2012 IEEE.

  17. Modeling regulation of zinc uptake via ZIP transporters in yeast and plant roots.

    Directory of Open Access Journals (Sweden)

    Juliane Claus

    Full Text Available In yeast (Saccharomyces cerevisiae and plant roots (Arabidopsis thaliana zinc enters the cells via influx transporters of the ZIP family. Since zinc is both essential for cell function and toxic at high concentrations, tight regulation is essential for cell viability. We provide new insight into the underlying mechanisms, starting from a general model based on ordinary differential equations and adapting it to the specific cases of yeast and plant root cells. In yeast, zinc is transported by the transporters ZRT1 and ZRT2, which are both regulated by the zinc-responsive transcription factor ZAP1. Using biological data, parameters were estimated and analyzed, confirming the different affinities of ZRT1 and ZRT2 reported in the literature. Furthermore, our model suggests that the positive feedback in ZAP1 production has a stabilizing function at high influx rates. In plant roots, various ZIP transporters play a role in zinc uptake. Their regulation is largely unknown, but bZIP transcription factors are thought to be involved. We set up three putative models based on: an activator only, an activator with dimerization and an activator-inhibitor pair. These were fitted to measurements and analyzed. Simulations show that the activator-inhibitor model outperforms the other two in providing robust and stable homeostasis at reasonable parameter ranges.

  18. Regulation of symbiotic nitrogen fixation in root nodules of alfalfa (Medicago sativa) infected with Rhizobium meliloti.

    Science.gov (United States)

    Kamberger, W

    1977-10-24

    Symbiotic nitrogen fixation of Rhizobium meliloti bacteroids in Medicago sativa root nodules was suppressed by several inorganic nitrogen sources. Amino acids like glutamine, glutamic acid and aspartic acid, which can serve as sole nitrogen sources for the unnodulated plant did not influence nitrogenase activity of effective nodules, even at high concetrations. Ammonia and nitrate suppressed symbiotic nitrogen fixation in vivo only at concentrations much higher than those needed for suppression of nitrogenase activity in free living nitrogen fixing bacteria. The kinetics of suppression were slow compared with that of free living nitrogen fixing bacteria. On the other hand, nitrite, which acts as a direct inhibitor of nitrogenase, suppressed very quickly and at low concentrations. Glutamic acid and glutamine enhanced the effect of ammonia dramatically, while the suppression by nitrate was enhanced only slightly.

  19. Physiological and Molecular Analysis of Aluminium-Induced Organic Acid Anion Secretion from Grain Amaranth (Amaranthus hypochondriacus L. Roots

    Directory of Open Access Journals (Sweden)

    Wei Fan

    2016-04-01

    Full Text Available Grain amaranth (Amaranthus hypochondriacus L. is abundant in oxalate and can secrete oxalate under aluminium (Al stress. However, the features of Al-induced secretion of organic acid anions (OA and potential genes responsible for OA secretion are poorly understood. Here, Al-induced OA secretion in grain amaranth roots was characterized by ion charomatography and enzymology methods, and suppression subtractive hybridization (SSH together with quantitative real-time PCR (qRT-PCR was used to identify up-regulated genes that are potentially involved in OA secretion. The results showed that grain amaranth roots secrete both oxalate and citrate in response to Al stress. The secretion pattern, however, differs between oxalate and citrate. Neither lanthanum chloride (La nor cadmium chloride (Cd induced OA secretion. A total of 84 genes were identified as up-regulated by Al, in which six genes were considered as being potentially involved in OA secretion. The expression pattern of a gene belonging to multidrug and toxic compound extrusion (MATE family, AhMATE1, was in close agreement with that of citrate secretion. The expression of a gene encoding tonoplast dicarboxylate transporter and four genes encoding ATP-binding cassette transporters was differentially regulated by Al stress, but the expression pattern was not correlated well with that of oxalate secretion. Our results not only reveal the secretion pattern of oxalate and citrate from grain amaranth roots under Al stress, but also provide some genetic information that will be useful for further characterization of genes involved in Al toxicity and tolerance mechanisms.

  20. Physiological and Molecular Analysis of Aluminium-Induced Organic Acid Anion Secretion from Grain Amaranth (Amaranthus hypochondriacus L.) Roots

    Science.gov (United States)

    Fan, Wei; Xu, Jia-Meng; Lou, He-Qiang; Xiao, Chuan; Chen, Wei-Wei; Yang, Jian-Li

    2016-01-01

    Grain amaranth (Amaranthus hypochondriacus L.) is abundant in oxalate and can secrete oxalate under aluminium (Al) stress. However, the features of Al-induced secretion of organic acid anions (OA) and potential genes responsible for OA secretion are poorly understood. Here, Al-induced OA secretion in grain amaranth roots was characterized by ion charomatography and enzymology methods, and suppression subtractive hybridization (SSH) together with quantitative real-time PCR (qRT-PCR) was used to identify up-regulated genes that are potentially involved in OA secretion. The results showed that grain amaranth roots secrete both oxalate and citrate in response to Al stress. The secretion pattern, however, differs between oxalate and citrate. Neither lanthanum chloride (La) nor cadmium chloride (Cd) induced OA secretion. A total of 84 genes were identified as up-regulated by Al, in which six genes were considered as being potentially involved in OA secretion. The expression pattern of a gene belonging to multidrug and toxic compound extrusion (MATE) family, AhMATE1, was in close agreement with that of citrate secretion. The expression of a gene encoding tonoplast dicarboxylate transporter and four genes encoding ATP-binding cassette transporters was differentially regulated by Al stress, but the expression pattern was not correlated well with that of oxalate secretion. Our results not only reveal the secretion pattern of oxalate and citrate from grain amaranth roots under Al stress, but also provide some genetic information that will be useful for further characterization of genes involved in Al toxicity and tolerance mechanisms. PMID:27144562

  1. Physiological and Molecular Analysis of Aluminium-Induced Organic Acid Anion Secretion from Grain Amaranth (Amaranthus hypochondriacus L.) Roots.

    Science.gov (United States)

    Fan, Wei; Xu, Jia-Meng; Lou, He-Qiang; Xiao, Chuan; Chen, Wei-Wei; Yang, Jian-Li

    2016-04-30

    Grain amaranth (Amaranthus hypochondriacus L.) is abundant in oxalate and can secrete oxalate under aluminium (Al) stress. However, the features of Al-induced secretion of organic acid anions (OA) and potential genes responsible for OA secretion are poorly understood. Here, Al-induced OA secretion in grain amaranth roots was characterized by ion charomatography and enzymology methods, and suppression subtractive hybridization (SSH) together with quantitative real-time PCR (qRT-PCR) was used to identify up-regulated genes that are potentially involved in OA secretion. The results showed that grain amaranth roots secrete both oxalate and citrate in response to Al stress. The secretion pattern, however, differs between oxalate and citrate. Neither lanthanum chloride (La) nor cadmium chloride (Cd) induced OA secretion. A total of 84 genes were identified as up-regulated by Al, in which six genes were considered as being potentially involved in OA secretion. The expression pattern of a gene belonging to multidrug and toxic compound extrusion (MATE) family, AhMATE1, was in close agreement with that of citrate secretion. The expression of a gene encoding tonoplast dicarboxylate transporter and four genes encoding ATP-binding cassette transporters was differentially regulated by Al stress, but the expression pattern was not correlated well with that of oxalate secretion. Our results not only reveal the secretion pattern of oxalate and citrate from grain amaranth roots under Al stress, but also provide some genetic information that will be useful for further characterization of genes involved in Al toxicity and tolerance mechanisms.

  2. Multilayered Organization of Jasmonate Signalling in the Regulation of Root Growth.

    Directory of Open Access Journals (Sweden)

    Debora Gasperini

    2015-06-01

    Full Text Available Physical damage can strongly affect plant growth, reducing the biomass of developing organs situated at a distance from wounds. These effects, previously studied in leaves, require the activation of jasmonate (JA signalling. Using a novel assay involving repetitive cotyledon wounding in Arabidopsis seedlings, we uncovered a function of JA in suppressing cell division and elongation in roots. Regulatory JA signalling components were then manipulated to delineate their relative impacts on root growth. The new transcription factor mutant myc2-322B was isolated. In vitro transcription assays and whole-plant approaches revealed that myc2-322B is a dosage-dependent gain-of-function mutant that can amplify JA growth responses. Moreover, myc2-322B displayed extreme hypersensitivity to JA that totally suppressed root elongation. The mutation weakly reduced root growth in undamaged plants but, when the upstream negative regulator NINJA was genetically removed, myc2-322B powerfully repressed root growth through its effects on cell division and cell elongation. Furthermore, in a JA-deficient mutant background, ninja1 myc2-322B still repressed root elongation, indicating that it is possible to generate JA-responses in the absence of JA. We show that NINJA forms a broadly expressed regulatory layer that is required to inhibit JA signalling in the apex of roots grown under basal conditions. By contrast, MYC2, MYC3 and MYC4 displayed cell layer-specific localisations and MYC3 and MYC4 were expressed in mutually exclusive regions. In nature, growing roots are likely subjected to constant mechanical stress during soil penetration that could lead to JA production and subsequent detrimental effects on growth. Our data reveal how distinct negative regulatory layers, including both NINJA-dependent and -independent mechanisms, restrain JA responses to allow normal root growth. Mechanistic insights from this work underline the importance of mapping JA signalling

  3. Production of oleanolic acid glycosides by hairy root established cultures of Calendula officinalis L.

    Science.gov (United States)

    Długosz, Marek; Wiktorowska, Ewa; Wiśniewska, Anita; Pączkowski, Cezary

    2013-01-01

    In order to initiate hairy root culture initiation cotyledons and hypocotyls of Calendula officinalis L. were infected with Agrobacterium rhizogenes strain ATCC 15834 or the same strain containing pCAMBIA 1381Z vector with β-glucuronidase reporter gene under control of promoter of NIK (Nematode Induced Kinase) gene. The efficiency of induction of hairy roots reached 33.8% for cotyledons and 66.6% for hypocotyls together for both transformation experiments. Finally, eight control and nine modified lines were established as a long-term culture. The hairy root cultures showed the ability to synthesize oleanolic acid mainly (97%) as glycosides; control lines contained it at the average 8.42 mg · g(-1) dry weight in tissue and 0.23 mg · dm(-3) in medium; modified lines: 4.59 mg · g(-1) for the tissue, and 0.48 mg · dm(-3) for the medium. Additionally lines showed high positive correlation between dry/fresh weight and oleanolic acid concentration in tissue. Using the Killiani mixture in acidic hydrolysis of oleanolic acid glycosides released free aglycones that were partially acetylated in such conditions.

  4. Effects of root-zone acidity on utilization of nitrate and ammonium in tobacco plants

    Science.gov (United States)

    Henry, L. T.; Raper, C. D. Jr; Raper CD, J. r. (Principal Investigator)

    1989-01-01

    Tobacco (Nicotiana tabacum L., cv. 'Coker 319') plants were grown for 28 days in flowing nutrient culture containing either 1.0 mM NO3- or 1.0 mM NH4+ as the nitrogen source in a complete nutrient solution. Acidities of the solutions were controlled at pH 6.0 or 4.0 for each nitrogen source. Plants were sampled at intervals of 6 to 8 days for determination of dry matter and nitrogen accumulation. Specific rates of NO3- or NH4+ uptake (rate of uptake per unit root mass) were calculated from these data. Net photosynthetic rates per unit leaf area were measured on attached leaves by infrared gas analysis. When NO3- [correction of NO-] was the sole nitrogen source, root growth and nitrogen uptake rate were unaffected by pH of the solution, and photosynthetic activity of leaves and accumulation of dry matter and nitrogen in the whole plant were similar. When NH4+ was the nitrogen source, photosynthetic rate of leaves and accumulation of dry matter and nitrogen in the whole plant were not statistically different from NO3(-) -fed plants when acidity of the solution was controlled at pH 6.0. When acidity for NH4(+) -fed plants was increased to pH 4.0, however, specific rate of NH4+ uptake decreased by about 50% within the first 6 days of treatment. The effect of acidity on root function was associated with a decreased rate of accumulation of nitrogen in shoots that was accompanied by a rapid cessation of leaf development between days 6 and 13. The decline in leaf growth rate of NH4(+) -fed plants at pH 4.0 was followed by reductions in photosynthetic rate per unit leaf area. These responses of NH4(+) -fed plants to increased root-zone acidity are characteristic of the sequence of responses that occur during onset of nitrogen stress.

  5. Rooting of healthy and CVC-affected 'Valência' sweet orange stem cuttings, through the use of plant regulators

    Directory of Open Access Journals (Sweden)

    Gustavo Habermann

    2006-01-01

    Full Text Available Citrus variegated chlorosis (CVC is a disease caused by Xylella fastidiosa. Using different concentrations of plant regulators, such as auxins (indole-3-butyric acid and gibberellic acid biosynthesis-inhibitor (paclobutrazol, physiological rooting capacity of healthy and CVC-affected stem cuttings were evaluated in order to investigate the importance of plant hormone imbalance and xylem occlusion in plants with CVC. The percentages of dead, alive and rooted cuttings, cuttings with callus and mean number of roots per cuttings did not show statistical differences in response to the distinct concentrations of synthetic plant regulators. There were differences only between healthy and CVC-affected cuttings. This showed the importance of xylem occlusion and diffusive disturbances in diseased plants, in relation to root initiation capacity and hormonal translocation in the plant tissue.Clorose variegada dos citros (CVC é uma doença causada por Xylella fastidiosa, podendo determinar oclusão do xilema e desbalanço hormonal, o que por fim está relacionado ao processo de iniciação radicial em estacas. Usando diferentes concentrações de fitorreguladores, como auxinas (ácido 3-indol butírico e inibidores da biossíntese de ácido giberélico (paclobutrazol, que são promotores do enraizamento de estacas, verificou-se a capacidade fisiológica de enraizamento de estacas sadias e com CVC, a fim de investigar a importância do desbalanço hormonal e oclusão do xilema em plantas doentes. As porcentagens de estacas mortas, vivas, enraizadas e com calo e o número médio de raízes por estaca não mostraram diferenças estatísticas em resposta às diferentes concentrações dos reguladores vegetais sintéticos. Houve diferenças apenas entre estacas sadias e doentes. Isto aponta a importância da oclusão do xilema e distúrbios difusivos em plantas doentes, em relação à capacidade de iniciação radicial e à translocação hormonal no tecido

  6. Cloning and characterization of acid invertase genes in the roots of the metallophyte Kummerowia stipulacea (Maxim.) Makino from two populations: Differential expression under copper stress.

    Science.gov (United States)

    Zhang, Luan; Xiong, Zhi-ting; Xu, Zhong-rui; Liu, Chen; Cai, Shen-wen

    2014-06-01

    The roots of metallophytes serve as the key interface between plants and heavy metal-contaminated underground environments. It is known that the roots of metallicolous plants show a higher activity of acid invertase enzymes than those of non-metallicolous plants when under copper stress. To test whether the higher activity of acid invertases is the result of increased expression of acid invertase genes or variations in the amino acid sequences between the two population types, we isolated full cDNAs for acid invertases from two populations of Kummerowia stipulacea (from metalliferous and non-metalliferous soils), determined their nucleotide sequences, expressed them in Pichia pastoris, and conducted real-time PCR to determine differences in transcript levels during Cu stress. Heterologous expression of acid invertase cDNAs in P. pastoris indicated that variations in the amino acid sequences of acid invertases between the two populations played no significant role in determining enzyme characteristics. Seedlings of K. stipulacea were exposed to 0.3µM Cu(2+) (control) and 10µM Cu(2+) for 7 days under hydroponics׳ conditions. The transcript levels of acid invertases in metallicolous plants were significantly higher than in non-metallicolous plants when under copper stress. The results suggest that the expression of acid invertase genes in metallicolous plants of K. stipulacea differed from those in non-metallicolous plants under such conditions. In addition, the sugars may play an important role in regulating the transcript level of acid invertase genes and acid invertase genes may also be involved in root/shoot biomass allocation.

  7. Abscisic acid coordinates nod factor and cytokinin signaling during the regulation of nodulation in Medicago truncatula.

    Science.gov (United States)

    Ding, Yiliang; Kalo, Peter; Yendrek, Craig; Sun, Jongho; Liang, Yan; Marsh, John F; Harris, Jeanne M; Oldroyd, Giles E D

    2008-10-01

    Nodulation is tightly regulated in legumes to ensure appropriate levels of nitrogen fixation without excessive depletion of carbon reserves. This balance is maintained by intimately linking nodulation and its regulation with plant hormones. It has previously been shown that ethylene and jasmonic acid (JA) are able to regulate nodulation and Nod factor signal transduction. Here, we characterize the nature of abscisic acid (ABA) regulation of nodulation. We show that application of ABA inhibits nodulation, bacterial infection, and nodulin gene expression in Medicago truncatula. ABA acts in a similar manner as JA and ethylene, regulating Nod factor signaling and affecting the nature of Nod factor-induced calcium spiking. However, this action is independent of the ethylene signal transduction pathway. We show that genetic inhibition of ABA signaling through the use of a dominant-negative allele of ABSCISIC ACID INSENSITIVE1 leads to a hypernodulation phenotype. In addition, we characterize a novel locus of M. truncatula, SENSITIVITY TO ABA, that dictates the sensitivity of the plant to ABA and, as such, impacts the regulation of nodulation. We show that ABA can suppress Nod factor signal transduction in the epidermis and can regulate cytokinin induction of the nodule primordium in the root cortex. Therefore, ABA is capable of coordinately regulating the diverse developmental pathways associated with nodule formation and can intimately dictate the nature of the plants' response to the symbiotic bacteria.

  8. Nitric Oxide-Mediated Maize Root Apex Responses to Nitrate are Regulated by Auxin and Strigolactones

    Directory of Open Access Journals (Sweden)

    Alessandro eManoli

    2016-01-01

    Full Text Available Nitrate (NO3- is a key element for crop production but its levels in agricultural soils are limited. Plants have developed mechanisms to cope with these NO3- fluctuations based on sensing nitrate at the root apex. Particularly, the transition zone (TZ of root apex has been suggested as a signalling-response zone. This study dissects cellular and molecular mechanisms underlying NO3- resupply effects on primary root growth in maize, confirming nitric oxide (NO as a putative modulator. Nitrate restoration induced primary root elongation within the first 2 h, corresponding to a stimulation of cell elongation at the basal border of the TZ. Xyloglucans (XGs immunolocalization together with Brefeldin A applications demonstrated that nitrate resupply induces XG accumulation. This effect was blocked by cPTIO (NO scavenger. Transcriptional analysis of ZmXET1 confirmed the stimulatory effect of nitrate on XGs accumulation in cells of the TZ. Immunolocalization analyses revealed a positive effect of nitrate resupply on auxin and PIN1 accumulation, but a transcriptional regulation of auxin biosynthesis/transport/signalling genes was excluded. Short-term nitrate treatment repressed the transcription of genes involved in strigolactones (SLs biosynthesis and transport, mainly in the TZ. Enhancement of carotenoid cleavage dioxygenases (CCDs transcription in presence of cPTIO indicated endogenous NO as a negative modulator of CCDs activity. Finally, treatment with the SLs-biosynthesis inhibitor (TIS108 restored the root growth in the nitrate-starved seedlings. Present report suggests that the NO-mediated root apex responses to nitrate are accomplished in cells of the TZ via integrative actions of auxin, NO and SLs.

  9. Gene expression regulation in the plant growth promoting Bacillus atrophaeus UCMB-5137 stimulated by maize root exudates.

    Science.gov (United States)

    Mwita, Liberata; Chan, Wai Yin; Pretorius, Theresa; Lyantagaye, Sylvester L; Lapa, Svitlana V; Avdeeva, Lilia V; Reva, Oleg N

    2016-09-15

    Despite successful use of Plant Growth Promoting Rhizobacteria (PGPR) in agriculture, little is known about specific mechanisms of gene regulation facilitating the effective communication between bacteria and plants during plant colonization. Active PGPR strain Bacillus atrophaeus UCMB-5137 was studied in this research. RNA sequencing profiles were generated in experiments where root exudate stimulations were used to mimic interactions between bacteria and plants. It was found that the gene regulation in B. atrophaeus UCMB-5137 in response to the root exudate stimuli differed from the reported gene regulation at similar conditions in B. amyloliquefaciens FZB42, which was considered as a paradigm PGPR. This difference was explained by hypersensitivity of UCMB-5137 to the root exudate stimuli impelling it to a sessile root colonization behavior through the CcpA-CodY-AbrB regulation. It was found that the transcriptional factor DegU also could play an important role in gene regulations during plant colonization. A significant stress caused by the root exudates on in vitro cultivated B. atrophaeus UCMB-5137 was noticed and discussed. Multiple cases of conflicted gene regulations showed scantiness of our knowledge on the regulatory network in Bacillus. Some of these conflicted regulations could be explained by interference of non-coding RNA (ncRNA). Search through differential expressed intergenic regions revealed 49 putative loci of ncRNA regulated by the root exudate stimuli. Possible target mRNA were predicted and a general regulatory network of B. atrophaeus UCMB-5137 genome was designed.

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

    Science.gov (United States)

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

    1996-01-01

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

  11. Micellar LC Separation of Sesquiterpenic Acids and Their Determination in Valeriana officinalis L. Root and Extracts

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    Artem U. Kulikov

    2012-01-01

    Full Text Available A simple micellar liquid chromatography (MLC method was developed and validated according to ICH Guidelines for the determination of sesquiterpenic acids (valerenic, hydroxyvalerenic, and acetoxyvalerenic acids in root and rhizome extract from Valeriana officinalis L. and valerian dry hydroalcoholic extract. Samples were analyzed on Nucleosil C18 column (150mm×4.6mm, 5 μm using an isocratic mobile phase which consisted of Brij 35 (5% (w/v aqueous solution; pH 2.3±0.1 by phosphoric acid and 1-butanol (6% (v/v; UV detection was at 220 nm. Micellar mobile phase using allows to fully separate valerenic acids within 25 minutes. Linearity for hydroxyvalerenic, acetoxyvalerenic, and valerenic acids was 1.9–27.9, 4.2–63.0, and 6.1–91·3 μg.mL−1, and limit of detection was 0.14, 0.037, and 0.09 μg·mL−1, respectively. Intraday and interday precisions were not less than 2% for all investigated compounds. The proposed method was found to be reproducible and convenient for quantitative analysis of sesquiterpenic acids in valerian root and related preparations.

  12. Lignan enhancement in hairy root cultures of Linum album using coniferaldehyde and methylenedioxycinnamic acid.

    Science.gov (United States)

    Ahmadian Chashmi, Najmeh; Sharifi, Mohsen; Behmanesh, Mehrdad

    2016-07-01

    Feeding experiments with hairy root cultures of Linum album have established that the extracellular coniferaldehyde is a good precursor for production of two lignans: lariciresinol (LARI) and pinoresinol (PINO). The accumulation of the LARI, PINO, and podophyllotoxin (PTOX) in hairy roots were enhanced about 14.8-, 8.7-, and 1.5-fold (107.61, 8.7 and 6.42 µg g(-1) Fresh Wight), respectively, by the addition of coniferaldehyde (2 mM) to the culture media (after 24 hr). This result was correlated with an increase pinoresinol/lariciresinol reductase (PLR) expression gene and cinnamyl alcohol dehydrogenase (CAD) activity in the fed hairy roots. Adding 3,4-(methylendioxy)cinnamic acid (MDCA) precursor did not influence on the lignans accumulation, but the lignin content of the hairy roots was increased. Moreover, the expression genes of phenylalanine ammonialyase (PAL), CAD, and cinnamoyl-CoA reductase (CCR) were influenced after feeding hairy roots with MDCA.

  13. A plant U-box protein, PUB4, regulates asymmetric cell division and cell proliferation in the root meristem

    NARCIS (Netherlands)

    Kinoshita, A.; Hove, ten C.A.; Tabata, R.; Yamada, M.; Shimizu, N.; Ishida, T.; Yamaguchi, K.; Shigenobu, S.; Takebayashi, Y.; Luchies, J.; Kobayashi, M.; Kurata, T.; Wada, T.; Seo, M.; Hasebe, M.; Blilou, I.; Fukuda, H.; Scheres, B.; Heidstra, R.; Kamiya, Y.; Sawa, S.

    2015-01-01

    The root meristem (RM) is a fundamental structure that is responsible for postembryonic root growth. The RM contains the quiescent center (QC), stem cells and frequently dividing meristematic cells, in which the timing and the frequency of cell division are tightly regulated. In Arabidopsis thaliana

  14. Ethylene: a regulator of root architectural responses to soil phosphorus availability

    NARCIS (Netherlands)

    Borch, K.; Bouma, T.J.; Lynch, J.P.; Brown, K.M.

    1999-01-01

    The involvement of ethylene in root architectural responses to phosphorus availability was investigated in common bean (Phaseolus vulgaris L,) plants grown with sufficient and deficient phosphorus. Although phosphorus deficiency reduced root mass and lateral root number, main root length was

  15. The occurrence of 2-hydroxy-6-methoxybenzoic acid methyl ester in Securidaca longepedunculata Fresen root bark

    Directory of Open Access Journals (Sweden)

    Lognay G.

    2000-01-01

    Full Text Available As part of our ongoing search for natural fumigants from Senegalese plants, we have investigated Securicicidaca longepedunculata root barks and demonstrated that 2-hydroxy-benzoic acid methyl ester (methyl salicylate, I is responsible of their biocide effect against stored grain insects. A second unknown apparented product, II has been systematically observed in all analyzed samples. The present paper describes the identification of this molecule. The analytical investigations including GCMS, GLC and 1H-NMR. spectrometry led to the conclusion that II corresponds to the 2-hydroxy-6-methoxybenzoic acid methyl ester.

  16. New camptothecin and ellagic acid analogues from the root bark of Camptotheca acuminata.

    Science.gov (United States)

    Zhang, Zhizhen; Li, Shiyou; Zhang, Shanmin; Liang, Chun; Gorenstein, David; Beasley, R Scott

    2004-12-01

    As part of a study on chemical constituents of Camptotheca species, one new natural camptothecin analogue (2), two new alkaloids (3, 4), one new ellagic acid analogue (5), and 19 known compounds (1, 6-23) have been isolated from the root bark, stem bark, fruits, and leaves of Camptotheca acuminata Decaisne. The structures of 2-5 were determined from spectral data to be 10-methoxy-20-O-acetylcamptothecin (2), 20-O-beta-glucopyranosyl 18-hydroxycamptothecin (3), 20-formylbenz indolizino [1,2-b]quino-line-11(13H)-one (4), and 3,4-methylenedioxy-3'-O-methyl-5'-hydroxyellagic acid (5).

  17. Alkaline stress and iron deficiency regulate iron uptake and riboflavin synthesis gene expression differently in root and leaf tissue: implications for iron deficiency chlorosis

    Science.gov (United States)

    Hsieh, En-Jung; Waters, Brian M.

    2016-01-01

    Iron (Fe) is an essential mineral that has low solubility in alkaline soils, where its deficiency results in chlorosis. Whether low Fe supply and alkaline pH stress are equivalent is unclear, as they have not been treated as separate variables in molecular physiological studies. Additionally, molecular responses to these stresses have not been studied in leaf and root tissues simultaneously. We tested how plants with the Strategy I Fe uptake system respond to Fe deficiency at mildly acidic and alkaline pH by measuring root ferric chelate reductase (FCR) activity and expression of selected Fe uptake genes and riboflavin synthesis genes. Alkaline pH increased cucumber (Cucumis sativus L.) root FCR activity at full Fe supply, but alkaline stress abolished FCR response to low Fe supply. Alkaline pH or low Fe supply resulted in increased expression of Fe uptake genes, but riboflavin synthesis genes responded to Fe deficiency but not alkalinity. Iron deficiency increased expression of some common genes in roots and leaves, but alkaline stress blocked up-regulation of these genes in Fe-deficient leaves. In roots of the melon (Cucumis melo L.) fefe mutant, in which Fe uptake responses are blocked upstream of Fe uptake genes, alkaline stress or Fe deficiency up-regulation of certain Fe uptake and riboflavin synthesis genes was inhibited, indicating a central role for the FeFe protein. These results suggest a model implicating shoot-to-root signaling of Fe status to induce Fe uptake gene expression in roots. PMID:27605716

  18. Effect of Hot water and dilute acid pretreatment on the chemical properties of liquorice root

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    zahra takzare

    2016-06-01

    Full Text Available Abstract In this study, the liquorice root (Glycyrrhiza glabra that was extracted in the factory in Kerman province, pre-hydrolyzed and then chemical compositions (Extractives, Lignin content, Holocellulose percent, the hydrolysis process yield and weight loss of the waste was measured. Pre-hydrolysis process was done on the above mentioned waste by hot water, hot water followed by 0.5 percent sulfuric acid and also alone sulfuric acid with different concentrations (0.5, 1, 1.5 and 2 percent The samples were pre-hydrolyzed in hot water at 150 °C and 30, 60 and 90 minutes as well as in the mixture of hot water and 0.5 % sulfuric acid at 150 °C and 60 minutes and also in pure sulfuric acid, at 130 °C and at 60 minutes. The results showed that the pre-hydrolyzed treatment with hot water in 60 minutes had been favorable performance in the respect of weight loss, lignin content and holocellulose percent. Also, in the case of pre-treatment including sulfuric acid, 2% dose can be good selected option in term of maximum holocellulose percent and minimum lignin content so that it can be suggested to produce higher value-added products such as bioethanol from licorice root bid.

  19. Rice genes involved in phytosiderophore biosynthesis are synchronously regulated during the early stages of iron deficiency in roots.

    Science.gov (United States)

    Itai, Reiko Nakanishi; Ogo, Yuko; Kobayashi, Takanori; Nakanishi, Hiromi; Nishizawa, Naoko K

    2013-06-25

    The rice transcription factors IDEF1, IDEF2, and OsIRO2 have been identified as key regulators of the genes that control iron (Fe) uptake, including the biosynthesis of mugineic acid-family phytosiderophores (MAs). To clarify the onset of Fe deficiency, changes in gene expression were examined by microarray analysis using rice roots at 3, 6, 9, 12, 24, and 36 h after the onset of Fe-deficiency treatment. More than 1000 genes were found to be upregulated over a time course of 36 h. Expression of MAs-biosynthetic genes, OsIRO2, and the Fe3+-MAs complex transporter OsYSL15 was upregulated at the 24 h and 36 h time points. Moreover, these genes showed very similar patterns of expression changes, but their expression patterns were completely different from those of a metallothionein gene (OsIDS1) and the Fe2+-transporter genes OsIRT1 and OsIRT2. OsIDS1 expression was upregulated by the 6 h time point. The early induction of OsIDS1 expression was distinct from the other Fe-deficiency-inducible genes investigated and suggested a functional relationship with heavy-metal homeostasis during the early stages of Fe deficiency. We showed that many genes related to MAs biosynthesis and transports were regulated by a distinct mechanism in roots. Furthermore, differences in expression changes and timing in response to Fe deficiency implied that different combinations of gene regulation mechanisms control the initial responses to Fe deficiency.

  20. Nitric Oxide-Mediated Maize Root Apex Responses to Nitrate are Regulated by Auxin and Strigolactones.

    Science.gov (United States)

    Manoli, Alessandro; Trevisan, Sara; Voigt, Boris; Yokawa, Ken; Baluška, František; Quaggiotti, Silvia

    2015-01-01

    Nitrate (NO3 (-)) is a key element for crop production but its levels in agricultural soils are limited. Plants have developed mechanisms to cope with these NO3 (-) fluctuations based on sensing nitrate at the root apex. Particularly, the transition zone (TZ) of root apex has been suggested as a signaling-response zone. This study dissects cellular and molecular mechanisms underlying NO3 (-) resupply effects on primary root (PR) growth in maize, confirming nitric oxide (NO) as a putative modulator. Nitrate restoration induced PR elongation within the first 2 h, corresponding to a stimulation of cell elongation at the basal border of the TZ. Xyloglucans (XGs) immunolocalization together with Brefeldin A applications demonstrated that nitrate resupply induces XG accumulation. This effect was blocked by cPTIO (NO scavenger). Transcriptional analysis of ZmXET1 confirmed the stimulatory effect of nitrate on XGs accumulation in cells of the TZ. Immunolocalization analyses revealed a positive effect of nitrate resupply on auxin and PIN1 accumulation, but a transcriptional regulation of auxin biosynthesis/transport/signaling genes was excluded. Short-term nitrate treatment repressed the transcription of genes involved in strigolactones (SLs) biosynthesis and transport, mainly in the TZ. Enhancement of carotenoid cleavage dioxygenases (CCDs) transcription in presence of cPTIO indicated endogenous NO as a negative modulator of CCDs activity. Finally, treatment with the SLs-biosynthesis inhibitor (TIS108) restored the root growth in the nitrate-starved seedlings. Present report suggests that the NO-mediated root apex responses to nitrate are accomplished in cells of the TZ via integrative actions of auxin, NO and SLs.

  1. Cell identity regulators link development and stress responses in the Arabidopsis root.

    Science.gov (United States)

    Iyer-Pascuzzi, Anjali S; Jackson, Terry; Cui, Hongchang; Petricka, Jalean J; Busch, Wolfgang; Tsukagoshi, Hironaka; Benfey, Philip N

    2011-10-18

    Stress responses in plants are tightly coordinated with developmental processes, but interaction of these pathways is poorly understood. We used genome-wide assays at high spatiotemporal resolution to understand the processes that link development and stress in the Arabidopsis root. Our meta-analysis finds little evidence for a universal stress response. However, common stress responses appear to exist with many showing cell type specificity. Common stress responses may be mediated by cell identity regulators because mutations in these genes resulted in altered responses to stress. Evidence for a direct role for cell identity regulators came from genome-wide binding profiling of the key regulator SCARECROW, which showed binding to regulatory regions of stress-responsive genes. Coexpression in response to stress was used to identify genes involved in specific developmental processes. These results reveal surprising linkages between stress and development at cellular resolution, and show the power of multiple genome-wide data sets to elucidate biological processes.

  2. Organic acid exudation from the roots of Cunninghamia lanceolata and Pinus massoniana seedlings under low phosphorus stress

    Institute of Scientific and Technical Information of China (English)

    Yuanchun YU; Jian YU; Qihua SHAN; Li FANG; Defeng JIANG

    2008-01-01

    Organic acid exudation from the roots of Chinese fir (Cunninghamia lanceolata) and Masson pine (Pinus massoniana) seedlings under low phosphorus stress was studied using the solution culture method. The results revealed that organic acid exudation from the roots of Chinese fir and Masson pine seedlings under low phosphorus stress increased. Compared with P3 (KH2PO4, 0.5 mmol/L), the average organic acid exuda-tion from the root of Masson pine seedlings under P0 (KH2PO4, 0 mmol/L), P1 (KH2PO4, 0.03 mmol/L) and P2(KH2PO4, 0.09 mmol/L) increased by 328.6%, 267.9% and 126.4% respectively. Masson pine from Zhejiang Province in China had the highest organic acid exuda-tion. Under low phosphorus stress, the increase in organic acid exudation from the different provinces of Chinese fir and Masson pine varied. Masson pine from Zhejiang Province mainly increased oxalic acid, tartaric acid, citric acid and malic acid exudation, that from Guangxi Province mainly increased oxalic acid and tartaric acid exudation, and that from Guizhou Province, China mainly increased oxalic acid, tartaric acid and malic acid exudation. Chinese fir mainly increased oxalic acid and tartaric acid exudation.

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

    Science.gov (United States)

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

    2010-09-01

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

  4. Effect of Naphthalene Acetic Acid on the Adventitious Rooting in Shoot Cuttings of Andrographis paniculata (Burm.f. Wall. ex Nees: An Important Therapeutical Herb

    Directory of Open Access Journals (Sweden)

    Md. Sanower Hossain

    2016-01-01

    Full Text Available Andrographis paniculata is one of the most important therapeutical herbs, widely used in traditional medical systems for the treatment of diverse diseases for thousands of years. This study was carried out to assess the effect of 1-naphthaleneacetic acid (NAA on adventitious rooting in A. paniculata shoot cuttings. The cuttings were treated with six concentrations of NAA (0.5, 1.0, 1.5, 2.0, 2.5, and 3.0 mM by applying soaking method and cuttings without hormone (soaking in distilled water were considered as control. The cuttings were then inoculated into peat moss in the planting tray and incubated under complete shade for root induction. Water was sprayed on peat moss once daily to moisten it. The results showed that different concentrations of NAA significantly (P≤0.05 affected the rooting characteristics of A. paniculata and 2.5 mM of NAA was found to be more effective to induce rooting in young apical shoot (YAS cuttings compared to other concentrations and old apical shoot (OAS. This study also postulates that adventitious rooting response depends on the juvenility of plant material and concentration of growth regulator. This report describes a technique for adventitious rooting in A. paniculata, which could be feasible to use for commercial scale propagation of this plant.

  5. Effect of root derived organic acids on the activation of nutrients in the rhizosphere soil

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Four types of soils, including brown coniferous forest soil, dark brown soil, black soil, and black calic soil, sampled from three different places in northeast China were used in this test. The functions of two root-derived organic acids and water were simulated and compared in the activation of mineral nutrients from the rhizosphere soil. The results showed that the organic acids could activate the nutrients and the activated degree of the nutrient elements highly depended on the amount and types of the organic acid excreted and on the physiochemical and biochemical properties of the soil tested. The activation effect of the citric acid was obviously higher than that of malic acid in extracting Fe, Mn, Cu, and Zn for all the tested soil types. However, the activation efficiencies of P, K, Ca, and Mg extracting by the citric acid were not much higher, sometimes even lower, than those by malic acid. The solution concentration of all elements increased with increase of amount of the citric acid added.

  6. Mechanisms of gene regulation by fatty acids

    NARCIS (Netherlands)

    Georgiadi, A.; Kersten, A.H.

    2012-01-01

    Consumption of specific dietary fatty acids has been shown to influence risk and progression of several chronic diseases, such as cardiovascular disease, obesity, cancer, and arthritis. In recent years, insights into the mechanisms underlying the biological effects of fatty acids have improved consi

  7. Transcriptomic analysis reveals ethylene as stimulator and auxin as regulator of adventitious root formation in petunia cuttings

    Directory of Open Access Journals (Sweden)

    Uwe eDruege

    2014-09-01

    Full Text Available Adventitious root (AR formation in the stem base of cuttings is the basis for propagation of many plant species and petunia is used as model to study this developmental process. Following AR formation from 2 to 192 hours after excision (hpe of cuttings, transcriptome analysis by microarray revealed a change of the character of the rooting zone from stem base to root identity. The greatest shift in the number of differentially expressed genes was observed between 24 and 72 hpe, when the categories storage, mineral nutrient acquisition, anti-oxidative and secondary metabolism, and biotic stimuli showed a notable high number of induced genes. Analyses of phytohormone-related genes disclosed multifaceted changes of the auxin transport system, auxin conjugation and the auxin signal perception machinery indicating a reduction in auxin sensitivity and phase-specific responses of particular auxin-regulated genes. Genes involved in ethylene biosynthesis and action showed a more uniform pattern as a high number of respective genes were generally induced during the whole process of AR formation. The important role of ethylene for stimulating AR formation was demonstrated by the application of inhibitors of ethylene biosynthesis and perception as well as of the precursor aminocyclopropane-1-carboxylic acid, all changing the number and length of AR. A model is proposed showing the putative role of polar auxin transport and resulting auxin accumulation in initiation of subsequent changes in auxin homeostasis and signal perception with a particular role of Aux/IAA expression. These changes might in turn guide the entrance into the different phases of AR formation. Ethylene biosynthesis, which is stimulated by wounding and does probably also respond to other stresses and auxin, acts as important stimulator of AR formation probably via the expression of ethylene responsive transcription factor genes, whereas the timing of different phases seems to be controlled

  8. Rooting of jade vine (Strongylodon macrobotrys A. Gray cuttings treated with indolbutiric acid

    Directory of Open Access Journals (Sweden)

    Fabiana Rezende Muniz

    2015-12-01

    Full Text Available The jade vine (Strongylodon macrobotrys A. Gray, is native plant from Philippines. It has long blue-green pseudoracemes inflorescence, which makes it unique and incomparable. It is considered one of the most admired and sought vines, although rare in gardens. This study evaluated the effect of indolbutiric acid (IBA on the stalks rooting of this ornamental specie. Stem cuttings without leaves and with a couple of leaves cut in half, were collected from branches of a well developed jade vine plant and were immerged into dipping solutions with a concentration range of IBA (0, 500, 1.000, 2.000 and 4.000 mg L-1 for 15 seconds. Subsequently, the bases of the cuttings was planted in polystyrene trays containing vermiculite (one cutting per cell and maintained in an intermittent water mist chamber for a 80 days period. Then the percentage of stem rooting was assessed as well as the number of roots and the length of the main root. Jade vine plants can be produced byr stem cutting treated in a dipping solution containing an IBA concentration of 2.000 mg L-1.

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

    Science.gov (United States)

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

    1985-01-01

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

  10. Establishment of Hairy Root Cultures of Rhaponticum carthamoides (Willd. Iljin for the Production of Biomass and Caffeic Acid Derivatives

    Directory of Open Access Journals (Sweden)

    Ewa Skała

    2015-01-01

    Full Text Available The aim of the study was to obtain transformed roots of Rhaponticum carthamoides and evaluate their phytochemical profile. Hairy roots were induced from leaf explants by the transformation of Agrobacterium rhizogenes strains A4 and ATCC 15834. The best response (43% was achieved by infection with A4 strain. The effects of different liquid media (WPM, B5, SH with full and half-strength concentrations of macro- and micronutrients on biomass accumulation of the best grown hairy root line (RC3 at two different lighting conditions (light or dark were investigated. The highest biomass (93 g L−1 of the fresh weight after 35 days was obtained in WPM medium under periodic light. UPLC-PDA-ESI-MS3 and HPLC-PDA analyses of 80% aqueous methanol extracts from the obtained hairy roots revealed the presence of eleven caffeoylquinic acids and their derivatives and five flavonoid glycosides. The production of caffeoylquinic acids and their derivatives was elevated in hairy roots grown in the light. Only light-grown hairy roots demonstrated the capability for the biosynthesis of such flavonoid glycosides as quercetagetin, quercetin, luteolin, and patuletin hexosides. Chlorogenic acid, 3,5-di-O-caffeoylquinic acid and a tentatively identified tricaffeoylquinic acid derivative were detected as the major compounds present in the transformed roots.

  11. Efeito da época de estaquia, fitorreguladores e ácido bórico no enraizamento de estacas de porta-enxertos de videira Effect of pruning time, growth regulators and boric acid on rooting of grape rootstock cuttings

    Directory of Open Access Journals (Sweden)

    S. Leonel

    1993-05-01

    Full Text Available Estudaram-se as interações entre os ácidos indol-butírico, alfa-naftaleno-acético e bórico no desenvolvimento de raízes em estacas de porta-enxertos de videira (Vitis vinifera L.. As estacas tinham aproximadamente 25 cm de comprimento e, necessariamente, 2 gemas, sendo obtidas em três épocas distintas (janeiro, abril e julho e colocadas para enraizar em bandejas de isopor, tendo vermiculita como substrato, e mantidas sob nebulização. O tratamento constou da imersão de 2,5 cm da base das estacas em soluções, por um tempo de imersão de 1 minuto. Os tratamentos utilizados corresponderam a: 1 .000; 2.000 e 5.000 ppm de IBA; 1.500 e 3.000 ppm de NAA; 150 microgramas/ml de H3BO3; IBA 1.000; 2.000 e 5.000 + H3BO3 150 microgramas/ml e H2O. Avaliaram-se a porcentagem de enraizamento, o número médio de raízes formadas por estaca e o comprimento médio das raízes (mm aos 90 dias após a instalação, no mês de julho. O IBA 2.000 ppm propiciou o enraizamento em 88,87% das estacas, contudo não diferiu estatisticamente da testemunha (H2O-61,10%. A melhor época de coleta de estaca para o enraizamento foi o mês de julho (inverno.The effects of indolebutyric, naphtalen acetic and boric acids were studied on rooting of grape rootstock cuttings. The cuttings were 25 cm long with two buds and were taken in three different times (January, April and July. Rooting was carried out in styrofoam trays with vermiculite as substratum and under intermittent mist. Cuttings were imersed up to 2.5 cm from the base in solutions for one minute. The treatments were: 1,000; 2,000 and 5,000 ppm of IBA; 1,500 and 3,000 ppm of NAA; 150 micrograms/ml H3BO3; IBA 1,000; 2,000 and 5,000 ppm plus H3BO(3150 niicrograins/ml and H2O. Rooting percentage, average number of roots per cutting and average length of roots (mm were evaluated 90 days after planting, in July. IBA at 2,000 ppm was the best treatment with 88.8% of rooted cuttings. The best time for rooting was

  12. Tall or short? Slender or thick? A plant strategy for regulating elongation growth of roots by low concentrations of gibberellin.

    Science.gov (United States)

    Tanimoto, Eiichi

    2012-07-01

    Since the plant hormone gibberellin (GA) was discovered as a fungal toxin that caused abnormal elongation of rice shoots, the physiological function of GA has mainly been investigated in relation to the regulation of plant height. However, an indispensable role for GA in root growth has been elucidated by using severely GA-depleted plants, either with a gene mutation in GA biosynthesis or which have been treated by an inhibitor of GA biosynthesis. The molecular sequence of GA signalling has also been studied to understand GA functions in root growth. This review addresses research progress on the physiological functions of GA in root growth. Concentration-dependent stimulation of elongation growth by GA is important for the regulation of plant height and root length. Thus the endogenous level of GA and/or the GA sensitivity of shoots and roots plays a role in determining the shoot-to-root ratio of the plant body. Since the shoot-to-root ratio is an important parameter for agricultural production, control of GA production and GA sensitivity may provide a strategy for improving agricultural productivity. The sequence of GA signal transduction has recently been unveiled, and some component molecules are suggested as candidate in planta regulatory sites and as points for the artificial manipulation of GA-mediated growth control. This paper reviews: (1) the breakthrough dose-response experiments that show that root growth is regulated by GA in a lower concentration range than is required for shoot growth; (2) research on the regulation of GA biosynthesis pathways that are known predominantly to control shoot growth; and (3) recent research on GA signalling pathways, including GA receptors, which have been suggested to participate in GA-mediated growth regulation. This provides useful information to suggest a possible strategy for the selective control of shoot and root growth, and to explain how GA plays a role in rosette and liana plants with tall or short, and slender

  13. Calcium-regulated in vivo protein phosphorylation in Zea mays L. root tips

    Science.gov (United States)

    Raghothama, K. G.; Reddy, A. S.; Friedmann, M.; Poovaiah, B. W.

    1987-01-01

    Calcium dependent protein phosphorylation was studied in corn (Zea mays L.) root tips. Prior to in vivo protein phosphorylation experiments, the effect of calcium, ethyleneglycol-bis-(beta-aminoethyl ether)-N-N' -tetraacetic acid (EGTA) and calcium ionophore (A-23187) on phosphorus uptake was studied. Calcium increased phosphorus uptake, whereas EGTA and A-23187 decreased it. Consequently, phosphorus concentration in the media was adjusted so as to attain similar uptake in different treatments. Phosphoproteins were analyzed by two-dimensional gel electrophoresis. Distinct changes in phosphorylation were observed following altered calcium levels. Calcium depletion in root tips with EGTA and A-23187 decreased protein phosphorylation. However, replenishment of calcium following EGTA and ionophore pretreatment enhanced phosphorylation of proteins. Preloading of the root tips with 32P in the presence of EGTA and A-23187 followed by a ten minute calcium treatment, resulted in increased phosphorylation indicating the involvement of calcium, calcium and calmodulin-dependent kinases. Calmodulin antagonist W-7 was effective in inhibiting calcium-promoted phosphorylation. These studies suggest a physiological role for calcium-dependent phosphorylation in calcium-mediated processes in plants.

  14. Combined Effects of Lanthanum (III) and Acid Rain on Antioxidant Enzyme System in Soybean Roots.

    Science.gov (United States)

    Zhang, Xuanbo; Du, Yuping; Wang, Lihong; Zhou, Qing; Huang, Xiaohua; Sun, Zhaoguo

    2015-01-01

    Rare earth element pollution (REEs) and acid rain (AR) pollution simultaneously occur in many regions, which resulted in a new environmental issue, the combined pollution of REEs and AR. The effects of the combined pollution on the antioxidant enzyme system of plant roots have not been reported. Here, the combined effects of lanthanum ion (La3+), one type of REE, and AR on the antioxidant enzyme system of soybean roots were investigated. In the combined treatment of La3+ (0.08 mM) and AR, the cell membrane permeability and the peroxidation of cell membrane lipid of soybean roots increased, and the superoxide dismutase, catalase, peroxidase and reduced ascorbic acid served as scavengers of reactive oxygen species. In other combined treatments of La3+ (0.40 mM, 1.20 mM) and AR, the membrane permeability, malonyldialdehyde content, superoxide dismutase activity, peroxidase activity and reduced ascorbic acid content increased, while the catalase activity decreased. The increased superoxide dismutase activity, peroxidase activity and reduced ascorbic acid content were inadequate to scavenge the excess hydrogen peroxide and superoxide, leading to the damage of the cell membrane, which was aggravated with the increase in the concentration of La3+ and the level of AR. The deleterious effects of the combined treatment of La3+ and AR were stronger than those of the single treatment of La3+ or AR. Moreover, the activity of antioxidant enzyme system in the combined treatment group was affected directly and indirectly by mineral element content in soybean plants.

  15. K+ uptake in plant roots. The systems involved, their regulation and parallels in other organisms.

    Science.gov (United States)

    Nieves-Cordones, Manuel; Alemán, Fernando; Martínez, Vicente; Rubio, Francisco

    2014-05-15

    Potassium (K(+)) is an essential macronutrient for plants. It is taken into the plant by the transport systems present in the plasma membranes of root epidermal and cortical cells. The identity of these systems and their regulation is beginning to be understood and the systems of K(+) transport in the model species Arabidopsis thaliana remain far better characterized than in any other plant species. Roots can activate different K(+) uptake systems to adapt to their environment, important to a sessile organism that needs to cope with a highly variable environment. The mechanisms of K(+) acquisition in the model species A. thaliana are the best characterized at the molecular level so far. According to the current model, non-selective channels are probably the main pathways for K(+) uptake at high concentrations (>10mM), while at intermediate concentrations (1mM), the inward rectifying channel AKT1 dominates K(+) uptake. Under lower concentrations of external K(+) (100μM), AKT1 channels, together with the high-affinity K(+) uptake system HAK5 contribute to K(+) acquisition, and at extremely low concentrations (root K(+) uptake are shared by other organisms, whilst others are specific to plants. This indicates that some crucial properties of the ancestral of K(+) transport systems have been conserved through evolution while others have diverged among different kingdoms.

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

    Directory of Open Access Journals (Sweden)

    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.

  17. Regulation of uric acid metabolism and excretion.

    Science.gov (United States)

    Maiuolo, Jessica; Oppedisano, Francesca; Gratteri, Santo; Muscoli, Carolina; Mollace, Vincenzo

    2016-06-15

    Purines perform many important functions in the cell, being the formation of the monomeric precursors of nucleic acids DNA and RNA the most relevant one. Purines which also contribute to modulate energy metabolism and signal transduction, are structural components of some coenzymes and have been shown to play important roles in the physiology of platelets, muscles and neurotransmission. All cells require a balanced quantity of purines for growth, proliferation and survival. Under physiological conditions the enzymes involved in the purine metabolism maintain in the cell a balanced ratio between their synthesis and degradation. In humans the final compound of purines catabolism is uric acid. All other mammals possess the enzyme uricase that converts uric acid to allantoin that is easily eliminated through urine. Overproduction of uric acid, generated from the metabolism of purines, has been proven to play emerging roles in human disease. In fact the increase of serum uric acid is inversely associated with disease severity and especially with cardiovascular disease states. This review describes the enzymatic pathways involved in the degradation of purines, getting into their structure and biochemistry until the uric acid formation. Copyright © 2015. Published by Elsevier Ireland Ltd.

  18. Root transcriptomes of two acidic soil adapted Indica rice genotypes suggest diverse and complex mechanism of low phosphorus tolerance.

    Science.gov (United States)

    Tyagi, Wricha; Rai, Mayank

    2017-03-01

    Low phosphorus (P) tolerance in rice is a biologically and agronomically important character. Low P tolerant Indica-type rice genotypes, Sahbhagi Dhan (SD) and Chakhao Poreiton (CP), are adapted to acidic soils and show variable response to low P levels. Using RNAseq approach, transcriptome data was generated from roots of SD and CP after 15 days of low P treatment to understand differences and similarities at molecular level. In response to low P, number of genes up-regulated (1318) was more when compared with down-regulated genes (761). Eight hundred twenty-one genes found to be significantly regulated between SD and CP in response to low P. De novo assembly using plant database led to further identification of 1535 novel transcripts. Functional annotation of significantly expressed genes suggests two distinct methods of low P tolerance. While root system architecture in SD works through serine-threonine kinase PSTOL1, suberin-mediated cell wall modification seems to be key in CP. The transcription data indicated that CP relies more on releasing its internally bound Pi and coping with low P levels by transcriptional and translational modifications and using dehydration response-based signals. Role of P transporters seems to be vital in response to low P in CP while sugar- and auxin-mediated pathway seems to be preferred in SD. At least six small RNA clusters overlap with transcripts highly expressed under low P, suggesting role of RNA super clusters in nutrient response in plants. These results help us to understand and thereby devise better strategy to enhance low P tolerance in Indica-type rice.

  19. Hairy Root Cultures of Gymnema sylvestre R. Br. to Produce Gymnemic Acid.

    Science.gov (United States)

    Rajashekar, J; Kumar, Vadlapudi; Veerashree, V; Poornima, D V; Sannabommaji, Torankumar; Gajula, Hari; Giridhara, B

    2016-01-01

    Gymnema sylvestre R. Br. (Asclepiadaceae) is an endangered species extensively used in the management of diabetes, obesity, and treatment of various diseases. Uncontrolled exploitation to meet the increasing demand and low seed viability hastens the disappearance of the plant from its natural habitat. Hairy root culture provides a suitable alternative for the enhanced production of active principles. The current protocol provides the optimized culture conditions for the establishment of hairy root cultures and elicitation studies and also confirmation of stable integration of A. rhizogenes plasmid T-DNA into host genetic material by PCR and RT-PCR. Furthermore, it also discusses the suitable methods for the extraction procedures, and qualitative and quantitative analysis of gymnemic acid by HPTLC and HPLC.

  20. Truffles Regulate Plant Root Morphogenesis via the Production of Auxin and Ethylene1[C][W][OA

    Science.gov (United States)

    Splivallo, Richard; Fischer, Urs; Göbel, Cornelia; Feussner, Ivo; Karlovsky, Petr

    2009-01-01

    Truffles are symbiotic fungi that form ectomycorrhizas with plant roots. Here we present evidence that at an early stage of the interaction, i.e. prior to physical contact, mycelia of the white truffle Tuber borchii and the black truffle Tuber melanopsorum induce alterations in root morphology of the host Cistus incanus and the nonhost Arabidopsis (Arabidopsis thaliana; i.e. primary root shortening, lateral root formation, root hair stimulation). This was most likely due to the production of indole-3-acetic acid (IAA) and ethylene by the mycelium. Application of a mixture of the ethylene precursor 1-aminocyclopropane-1-carboxylic acid and IAA fully mimicked the root morphology induced by the mycelium for both host and nonhost plants. Application of the single hormones only partially mimicked it. Furthermore, primary root growth was not inhibited in the Arabidopsis auxin transport mutant aux1-7 by truffle metabolites while root branching was less effected in the ethylene-insensitive mutant ein2-LH. The double mutant aux1-7;ein2-LH displayed reduced sensitivity to fungus-induced primary root shortening and branching. In agreement with the signaling nature of truffle metabolites, increased expression of the auxin response reporter DR5∷GFP in Arabidopsis root meristems subjected to the mycelium could be observed, confirming that truffles modify the endogenous hormonal balance of plants. Last, we demonstrate that truffles synthesize ethylene from l-methionine probably through the α-keto-γ-(methylthio)butyric acid pathway. Taken together, these results establish the central role of IAA and ethylene as signal molecules in truffle/plant interactions. PMID:19535471

  1. [De novo sequencing and analysis of root transcriptome to reveal regulation of gene expression by moderate drought stress in Glycyrrhiza uralensis].

    Science.gov (United States)

    Zhang, Chun-rong; Sang, Xue-yu; Qu, Meng; Tang, Xiao-min; Cheng, Xuan-xuan; Pan, Li-ming; Yang, Quan

    2015-12-01

    Moderate drought stress has been found to promote the accumulation of active ingredients in Glycyrrhiza uralensis root and hence improve the medicinal quality. In this study, the transcriptomes of 6-month-old moderate drought stressed and control G. uralensis root (the relative water content in soil was 40%-45% and 70%-75%, respectively) were sequenced using Illumina HiSeq 2000. A total of 80,490 490 and 82 588 278 clean reads, 94,828 and 305,100 unigenes with N50 sequence of 1,007 and 1,125 nt were obtained in drought treated and control transcriptome, respectively. Differentially expressed genes analysis revealed that the genes of some cell wall enzymes such as β-xylosidase, legumain and GDP-L-fucose synthase were down-regulated indicating that moderate drought stress might inhibit the primary cell wall degradation and programmed cell death in root cells. The genes of some key enzymes involved in terpenoid and flavonoid biosynthesis were up-regulated by moderate drought stress might be the reason for the enhancement for the active ingredients accumulation in G. uralensis root. The promotion of the biosynthesis and signal transduction of auxin, ethylene and cytokinins by moderate drought stress might enhance the root formation and cell proliferation. The promotion of the biosynthesis and signal transduction of abscisic acid and jasmonic acid by moderate drought stress might enhance the drought stress tolerance in G. uralensis. The inhibition of the biosynthesis and signal transduction of gibberellin and brassinolide by moderate drought stress might retard the shoot growth in G. uralensis.

  2. Regulation of intestinal protein metabolism by amino acids.

    Science.gov (United States)

    Bertrand, Julien; Goichon, Alexis; Déchelotte, Pierre; Coëffier, Moïse

    2013-09-01

    Gut homeostasis plays a major role in health and may be regulated by quantitative and qualitative food intake. In the intestinal mucosa, an intense renewal of proteins occurs, at approximately 50% per day in humans. In some pathophysiological conditions, protein turnover is altered and may contribute to intestinal or systemic diseases. Amino acids are key effectors of gut protein turnover, both as constituents of proteins and as regulatory molecules limiting intestinal injury and maintaining intestinal functions. Many studies have focused on two amino acids: glutamine, known as the preferential substrate of rapidly dividing cells, and arginine, another conditionally essential amino acid. The effects of glutamine and arginine on protein synthesis appear to be model and condition dependent, as are the involved signaling pathways. The regulation of gut protein degradation by amino acids has been minimally documented until now. This review will examine recent data, helping to better understand how amino acids regulate intestinal protein metabolism, and will explore perspectives for future studies.

  3. Chemical signals and their regulations on the plant growth and water use efficiency of cotton seedlings under partial root-zone drying and different nitrogen applications

    Directory of Open Access Journals (Sweden)

    Wenrao Li

    2017-03-01

    Full Text Available Partial root-zone drying during irrigation (PRD has been shown effective in enhancing plant water use efficiency (WUE, however, the roles of chemical signals from root and shoot that are involved and the possible interactions affected by nitrogen nutrition are not clear. Pot-grown cotton (Gossypium spp. seedlings were treated with three levels of N fertilization and PRD. The concentrations of nitrate (NO3−, abscisic acid (ABA and the pH value of leaf and root xylem saps, biomass and WUE were measured. Results showed that PRD plants produced larger biomass and higher WUE than non-PRD plants, with significant changes in leaf xylem ABA, leaf and root xylem NO3− concentrations and pH values, under heterogeneous soil moisture conditions. Simultaneously, high-N treated plants displayed larger changes in leaf xylem ABA and higher root xylem NO3− concentrations, than in the medium- or low-N treated plants. However, the WUE of plants in the low-N treatment was higher than that of those in the high- and medium-N treatments. PRD and nitrogen levels respectively induced signaling responses of ABA/NO3− and pH in leaf or root xylem to affect WUE and biomass under different watering levels, although significant interactions of PRD and nitrogen levels were found when these signal molecules responded to soil drying. We conclude that these signaling chemicals are regulated by interaction of PRD and nitrogen status to regulate stomatal behavior, either directly or indirectly, and thus increase PRD plant WUE under less irrigation.

  4. Smad4-Shh-Nfic signaling cascade-mediated epithelial-mesenchymal interaction is crucial in regulating tooth root development.

    Science.gov (United States)

    Huang, Xiaofeng; Xu, Xun; Bringas, Pablo; Hung, Yee Ping; Chai, Yang

    2010-05-01

    Transforming growth factor beta (TGF-beta)/bone morphogenetic protein (BMP) signaling is crucial for regulating epithelial-mesenchymal interaction during organogenesis, and the canonical Smad pathway-mediated TGF-beta/BMP signaling plays important roles during development and disease. During tooth development, dental epithelial cells, known as Hertwig's epithelial root sheath (HERS), participate in root formation following crown development. However, the functional significance of HERS in regulating root development remains unknown. In this study we investigated the signaling mechanism of Smad4, the common Smad for TGF-beta/BMP signaling, in HERS in regulating root development. Tissue-specific inactivation of Smad4 in HERS results in abnormal enamel and dentin formation in K14-Cre;Smad4(fl/fl) mice. HERS enlarges but cannot elongate to guide root development without Smad4. At the molecular level, Smad4-mediated TGF-beta/BMP signaling is required for Shh expression in HERS and Nfic (nuclear factor Ic) expression in the cranial neural crest (CNC)-derived dental mesenchyme. Nfic is crucial for root development, and loss of Nfic results in a CNC-derived dentin defect similar to the one of K14-Cre;Smad4(fl/fl) mice. Significantly, we show that ectopic Shh induces Nfic expression in dental mesenchyme and partially rescues root development in K14-Cre;Smad4(fl/fl) mice. Taken together, our study has revealed an important signaling mechanism in which TGF-beta/BMP signaling relies on a Smad-dependent mechanism in regulating Nfic expression via Shh signaling to control root development. The interaction between HERS and the CNC-derived dental mesenchyme may guide the size, shape, and number of tooth roots.

  5. Ion absorption by bean roots and organic acid changes brought about through CO/sub 2/ fixation

    Energy Technology Data Exchange (ETDEWEB)

    Jackson, W.A.; Coleman, N.T.

    1959-01-01

    There appears to be a definite relationship between organic acid accumulation and ion absorption by roots. An understanding of the importance of CO/sub 2/ fixation and its relationship to ion absorption by plant roots is basic to the comprehension of the reactions in soil-root environment. Results are presented of a preliminary investigation into these phenomena. There is an indication that some factors known to influence the fixation of CO/sub 2/ by phosphoenolpyruvate carboxylase and malic dehydrogenase have similar effects on malate accumulation and K absorption by roots. The evidence indicates that the mechanisms responsible for K accumulation in root tissue are quite different when roots are exposed to solutions in the presence or in the absence of HCO/sub 3/.

  6. Poly-γ-Glutamic Acids Contribute to Biofilm Formation and Plant Root Colonization in Selected Environmental Isolates of Bacillus subtilis.

    Science.gov (United States)

    Yu, Yiyang; Yan, Fang; Chen, Yun; Jin, Christopher; Guo, Jian-Hua; Chai, Yunrong

    2016-01-01

    Bacillus subtilis is long known to produce poly-γ-glutamic acids (γ-PGA) as one of the major secreted polymeric substances. In B. subtilis, the regulation of γ-PGA production and its physiological role are still unclear. B. subtilis is also capable of forming structurally complex multicellular communities, or biofilms, in which an extracellular matrix consisting of secreted proteins and polysaccharides holds individual cells together. Biofilms were shown to facilitate B. subtilis-plant interactions. In this study, we show that different environmental isolates of B. subtilis, all capable of forming biofilms, vary significantly in γ-PGA production. This is possibly due to differential regulation of γ-PGA biosynthesis genes. In many of those environmental isolates, γ-PGA seems to contribute to robustness and complex morphology of the colony biofilms, suggesting a role of γ-PGA in biofilm formation. Our evidence further shows that in selected B. subtilis strains, γ-PGA also plays a role in root colonization by the bacteria, pinpointing a possible function of γ-PGA in B. subtilis-plant interactions. Finally, we found that several pathways co-regulate both γ-PGA biosynthesis genes and genes for the biofilm matrix in B. subtilis, but in an opposing fashion. We discussed potential biological significance of that.

  7. A P-Loop NTPase Regulates Quiescent Center Cell Division and Distal Stem Cell Identity through the Regulation of ROS Homeostasis in Arabidopsis Root

    Science.gov (United States)

    Yu, Qianqian; Tian, Huiyu; Liu, Jiajia; Zhang, Bing; Li, Xugang; Ding, Zhaojun

    2016-01-01

    Reactive oxygen species (ROS) are recognized as important regulators of cell division and differentiation. The Arabidopsis thaliana P-loop NTPase encoded by APP1 affects root stem cell niche identity through its control of local ROS homeostasis. The disruption of APP1 is accompanied by a reduction in ROS level, a rise in the rate of cell division in the quiescent center (QC) and the promotion of root distal stem cell (DSC) differentiation. Both the higher level of ROS induced in the app1 mutant by exposure to methyl viologen (MV), and treatment with hydrogen peroxide (H2O2) rescued the mutant phenotype, implying that both the increased rate of cell division in the QC and the enhancement in root DSC differentiation can be attributed to a low level of ROS. APP1 is expressed in the root apical meristem cell mitochondria, and its product is associated with ATP hydrolase activity. The key transcription factors, which are defining root distal stem niche, such as SCARECROW (SCR) and SHORT ROOT (SHR) are both significantly down-regulated at both the transcriptional and protein level in the app1 mutant, indicating that SHR and SCR are important downstream targets of APP1-regulated ROS signaling to control the identity of root QC and DSCs. PMID:27583367

  8. Small RNA deep sequencing identifies novel and salt-stress-regulated microRNAs from roots of Medicago sativa and Medicago truncatula.

    Science.gov (United States)

    Long, Rui-Cai; Li, Ming-Na; Kang, Jun-Mei; Zhang, Tie-Jun; Sun, Yan; Yang, Qing-Chuan

    2015-05-01

    Small 21- to 24-nucleotide (nt) ribonucleic acids (RNAs), notably the microRNA (miRNA), are emerging as a posttranscriptional regulation mechanism. Salt stress is one of the primary abiotic stresses that cause the crop losses worldwide. In saline lands, root growth and function of plant are determined by the action of environmental salt stress through specific genes that adapt root development to the restrictive condition. To elucidate the role of miRNAs in salt stress regulation in Medicago, we used a high-throughput sequencing approach to analyze four small RNA libraries from roots of Zhongmu-1 (Medicago sativa) and Jemalong A17 (Medicago truncatula), which were treated with 300 mM NaCl for 0 and 8 h. Each library generated about 20 million short sequences and contained predominantly small RNAs of 24-nt length, followed by 21-nt and 22-nt small RNAs. Using sequence analysis, we identified 385 conserved miRNAs from 96 families, along with 68 novel candidate miRNAs. Of all the 68 predicted novel miRNAs, 15 miRNAs were identified to have miRNA*. Statistical analysis on abundance of sequencing read revealed specific miRNA showing contrasting expression patterns between M. sativa and M. truncatula roots, as well as between roots treated for 0 and 8 h. The expression of 10 conserved and novel miRNAs was also quantified by quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR). The miRNA precursor and target genes were predicted by bioinformatics analysis. We concluded that the salt stress related conserved and novel miRNAs may have a large variety of target mRNAs, some of which might play key roles in salt stress regulation of Medicago.

  9. [Influence of exogenous gamma-aminobutyric acid (GABA) on GABA metabolism and amino acid contents in roots of melon seedling under hypoxia stress].

    Science.gov (United States)

    Wang, Chun-Yan; Li, Jing-Rui; Xia, Qing-Ping; Wu, Xiao-Lei; Gao, Hong-Bo

    2014-07-01

    This paper investigated the influence of gamma-aminobutyric acid (GABA) on GABA metabolism and amino acid content under hypoxia stress by accurately controlling the level of dissolved oxygen in hydroponics, using the roots of melon 'Xiyu 1' seedlings as the test material. The results showed that compared with the control, the growth of roots was inhibited seriously under hypoxia stress. Meanwhile, the hypoxia-treated roots had significantly higher activities of glutamate decarboxylase (GAD), glutamate dehydrogenase (GDH), glutamate synthase (GOGAT), glutamine synthetase (GS), alanine aminotransferase (ALT), aspartate aminotransferase (AST) as well as the contents of GABA, pyruvic acid, alanine (Ala) and aspartic acid (Asp). But the contents of glutamic acid (Glu) and alpha-keto glutaric acid in roots under hypoxia stress was obviously lower than those of the control. Exogenous treatment with GABA alleviated the inhibition effect of hypoxia stress on root growth, which was accompanied by an increase in the contents of endogenous GABA, Glu, alpha-keto glutaric acid and Asp. Furthermore, under hypoxia stress, the activities of GAD, GDH, GOGAT, GS, ALT, AST as well as the contents of pyruvic acid and Ala significantly decreased in roots treated with GABA. However, adding GABA and viny-gamma-aminobutyric acid (VGB) reduced the alleviation effect of GABA on melon seedlings under hypoxia stress. The results suggested that absorption of GABA by roots could alleviate the injury of hypoxia stress to melon seedlings. This meant that GABA treatment allows the normal physiological metabolism under hypoxia by inhibiting the GAD activity through feedback and maintaining higher Glu content as well as the bal- ance of carbon and nitrogen.

  10. Salicylic acid changes the properties of extracellular peroxidase activity secreted from wounded wheat (Triticum aestivum L.) roots.

    Science.gov (United States)

    Minibayeva, F; Mika, A; Lüthje, S

    2003-05-01

    Wheat ( Triticum aestivum L.) roots released proteins showing peroxidase activity in the apoplastic solution in response to wound stress. Preincubation of excised roots with 1 mM salicylic acid at pH 7.0 enhanced the guaiacol peroxidase activity of the extracellular solution (so-called extracellular peroxidase). The soluble enzymes were partially purified by precipitation with ammonium sulfate followed by size exclusion and ion exchange chromatography. Despite an increase in the total activity of secreted peroxidase induced by pretreatment of excised roots with salicylic acid, the specific activity of the partially purified protein was significantly lower compared to that of the control. Purification of the corresponding proteins by ion exchange chromatography indicates that several isoforms of peroxidase occurred in both control and salicylic acid-treated samples. The activities of the extracellular peroxidases secreted by the salicylic acid-treated roots responded differently to calcium and lectins compared with those from untreated roots. Taken together, our data suggest that salicylic acid changes the isoforms of peroxidase secreted by wounded wheat roots.

  11. Indole alkaloid sulfonic acids from an aqueous extract of Isatis indigotica roots and their antiviral activity

    Directory of Open Access Journals (Sweden)

    Lingjie Meng

    2017-05-01

    Full Text Available Six new indole alkaloid sulfonic acids (1–6, together with two analogues (7 and 8 that were previously reported as synthetic products, were isolated from an aqueous extract of the Isatis indigotica root. Their structures including the absolute configurations were determined by spectroscopic data analysis, combined with enzyme hydrolysis and comparison of experimental circular dichroism and calculated electronic circular dichroism spectra. In the preliminary assay, compounds 2 and 4 showed antiviral activity against Coxsackie virus B3 and influenza virus A/Hanfang/359/95 (H3N2, respectively.

  12. Root-expressed maize lipoxygenase 3 negatively regulates induced systemic resistance to Colletotrichum graminicola in shoots.

    Science.gov (United States)

    Constantino, Nasie N; Mastouri, Fatemeh; Damarwinasis, Ramadhika; Borrego, Eli J; Moran-Diez, Maria E; Kenerley, Charley M; Gao, Xiquan; Kolomiets, Michael V

    2013-01-01

    We have previously reported that disruption of a maize root-expressed 9-lipoxygenase (9-LOX) gene, ZmLOX3, results in dramatic increase in resistance to diverse leaf and stalk pathogens. Despite evident economic significance of these findings, the mechanism behind this increased resistance remained elusive. In this study, we found that increased resistance of the lox3-4 mutants is due to constitutive activation of induced systemic resistance (ISR) signaling. We showed that ZmLOX3 lacked expression in leaves in response to anthracnose leaf blight pathogen Colletotrichum graminicola, but was expressed constitutively in the roots, thus, prompting our hypothesis: the roots of lox3-4 mutants are the source of increased resistance in leaves. Supporting this hypothesis, treatment of wild-type plants (WT) with xylem sap of lox3-4 mutant induced resistance to C. graminicola to the levels comparable to those observed in lox3-4 mutant. Moreover, treating mutants with the sap collected from WT plants partially restored the susceptibility to C. graminicola. lox3-4 mutants showed primed defense responses upon infection, which included earlier and greater induction of defense-related PAL and GST genes compared to WT. In addition to the greater expression of the octadecanoid pathway genes, lox3-4 mutant responded earlier and with a greater accumulation of H2O2 in response to C. graminicola infection or treatment with alamethicin. These findings suggest that lox3-4 mutants display constitutive ISR-like signaling. In support of this idea, root colonization by Trichoderma virens strain GV29-8 induced the same level of disease resistance in WT as the treatment with the mutant sap, but had no additional resistance effect in lox3-4 mutant. While treatment with T. virens GV29 strongly and rapidly suppressed ZmLOX3 expression in hydroponically grown WT roots, T. virens Δsml mutant, which is deficient in ISR induction, was unable to suppress expression of ZmLOX3, thus, providing genetic

  13. Rhizophagus irregularis as an elicitor of rosmarinic acid and antioxidant production by transformed roots of Ocimum basilicum in an in vitro co-culture system.

    Science.gov (United States)

    Srivastava, Shivani; Conlan, Xavier A; Cahill, David M; Adholeya, Alok

    2016-11-01

    Arbuscular mycorrhiza is a symbiotic association formed between plant roots and soil borne fungi that alter and at times improve the production of secondary metabolites. Detailed information is available on mycorrhizal development and its influence on plants grown under various edapho-climatic conditions, however, very little is known about their influence on transformed roots that are rich reserves of secondary metabolites. This raises the question of how mycorrhizal colonization progresses in transformed roots grown in vitro and whether the mycorrhizal fungus presence influences the production of secondary metabolites. To fully understand mycorrhizal ontogenesis and its effect on root morphology, root biomass, total phenolics, rosmarinic acid, caffeic acid and antioxidant production under in vitro conditions, a co-culture was developed between three Agrobacterium rhizogenes-derived, elite-transformed root lines of Ocimum basilicum and Rhizophagus irregularis. We found that mycorrhizal ontogenesis in transformed roots was similar to mycorrhizal roots obtained from an in planta system. Mycorrhizal establishment was also found to be transformed root line-specific. Colonization of transformed roots increased the concentration of rosmarinic acid, caffeic acid and antioxidant production while no effect was observed on root morphological traits and biomass. Enhancement of total phenolics and rosmarinic acid in the three mycorrhizal transformed root lines was found to be transformed root line-specific and age dependent. We reveal the potential of R. irregularis as a biotic elicitor in vitro and propose its incorporation into commercial in vitro secondary metabolite production via transformed roots.

  14. Co-regulation of root hair tip growth by ROP GTPases and nitrogen source modulated pH fluctuations.

    Science.gov (United States)

    Bloch, Daria; Monshausen, Gabriele; Gilroy, Simon; Yalovsky, Shaul

    2011-03-01

    Growth of plant cells involves tight regulation of the cytoskeleton and vesicle trafficking by processes including the action of the ROP small G proteins together with pH-modulated cell wall modifications. Yet, little is known on how these systems are coordinated. In a paper recently published in Plant Cell and Environment we show that ROPs/RACs function synergistically with NH4NO3-modulated pH fluctuations to regulate root hair growth. Root hairs expand exclusively at their apical end in a strictly polarized manner by a process known as tip growth. The highly polarized secretion at the apex is maintained by a complex network of factors including the spatial organization of the actin cytoskeleton, tip-focused ion gradients and by small G proteins. Expression of constitutively active ROP mutants disrupts polar growth, inducing the formation of swollen root hairs. Root hairs are also known to elongate in an oscillating manner, which is correlated with oscillatory H(+) fluxes at the tip. Our analysis shows that root hair elongation in wild type plants and swelling in transgenic plants expressing a constitutively active ROP11 (rop11(CA)) is sensitive to the presence of NH4(+) at concentrations higher than 1 mM and on NO3(-). The NH4(+) and NO3(-) ions did not affect the localization of ROP in the membrane but modulated pH fluctuations at the root hair tip. Actin organization and reactive oxygen species distribution were abnormal in rop11CA root hairs but were similar to wild type root hairs when seedlings were grown on medium lacking NH4(+) and / or NO3(-). These observations suggest that the nitrogen source-modulated pH fluctuations may function synergistically with ROP regulated signaling during root hair tip growth. Interestingly, under certain growth conditions, expression of rop11 (CA) suppressed ammonium toxicity, similar to auxin resistant mutants. In this Addendum article we discuss these findings and their implications.

  15. Apical microleakage of different root canal sealers after use of maleic acid and EDTA as final irrigants.

    Science.gov (United States)

    Ulusoy, Ozgür Ilke; Nayir, Yelda; Celik, Kezban; Yaman, Sis Darendeliler

    2014-01-01

    This study aimed to compare the effects of ethylenediaminetetraacetic acid (EDTA) and maleic acid (MA) on the sealing ability of various root canal sealers. Eighty root canals were instrumented and irrigated with either EDTA or MA. They were divided into eight experimental groups and obturated as follows: Group 1: MA + Hybrid Root SEAL/gutta-percha. Group 2: EDTA + Hybrid Root SEAL/gutta-percha. Group 3: MA + iRoot SP/gutta-percha. Group 4: EDTA + iRoot SP/gutta-percha. Group 5: MA + EndoREZ/EndoREZ points. Group 6: EDTA + EndoREZ/EndoREZ points. Group 7: MA + AH Plus/gutta-percha. Group 8: EDTA + AH Plus/gutta-percha. Another ten roots were used as negative and positive controls. The microleakage of each sample was measured at 2-min intervals for 8 min using the fluid filtration method. Data were statistically analyzed with one-way ANOVA, post-hoc Tukey, and paired-samples t tests. The minimum microleakage values were obtained from the teeth obturated with AH Plus and EndoREZ selaers (p EDTA in terms of microleakage (p EDTA. The type of final irrigation solution seems to influence the postobturation apical seal. Use of AH Plus and EndoREZ sealers showed better sealing ability compared with IRoot SP and Hybrid Root SEAL.

  16. Determination of caffeic acid in root and rhizome of Black cohosh (Cimicifuga racemosa (L. Nutt.

    Directory of Open Access Journals (Sweden)

    Zapala Karolina

    2014-06-01

    Full Text Available Cimicifuga racemosa, is a plant with a diverse and long history of medicinal use. Caffeic acid, bioactive compound, which often occurs with other polyphenols can influence the biological activity of this plant. The aim of our work was quantitative analysis of caffeic acid in roots and rhizomes of two varieties of C. racemosa. Analysis was performed by HPLC method. The extracts were separated on C18 reversed-phase column using mixture of methanol, water and formic acid (25:75:0.5 v/v/v as a mobile phase. The flow rate of eluent was 1.0 ml·min-1. The obtained validation parameters such as linearity, linear regression equation and precision expressed as a relative standard deviation were adequate for quantitative determination. Caffeic acid was found in all tested extracts. The highest total amount of caffeic acid was determined in C. racemosa var. racemosa (255.3 μg·g-1 while its concentration in C. racemosa var. cordifolia was significantly lower (213.0 μg·g-1.

  17. In site bioimaging of hydrogen sulfide uncovers its pivotal role in regulating nitric oxide-induced lateral root formation.

    Directory of Open Access Journals (Sweden)

    Yan-Jun Li

    Full Text Available Hydrogen sulfide (H2S is an important gasotransmitter in mammals. Despite physiological changes induced by exogenous H2S donor NaHS to plants, whether and how H2S works as a true cellular signal in plants need to be examined. A self-developed specific fluorescent probe (WSP-1 was applied to track endogenous H2S in tomato (Solanum lycopersicum roots in site. Bioimaging combined with pharmacological and biochemical approaches were used to investigate the cross-talk among H2S, nitric oxide (NO, and Ca(2+ in regulating lateral root formation. Endogenous H2S accumulation was clearly associated with primordium initiation and lateral root emergence. NO donor SNP stimulated the generation of endogenous H2S and the expression of the gene coding for the enzyme responsible for endogenous H2S synthesis. Scavenging H2S or inhibiting H2S synthesis partially blocked SNP-induced lateral root formation and the expression of lateral root-related genes. The stimulatory effect of SNP on Ca(2+ accumulation and CaM1 (calmodulin 1 expression could be abolished by inhibiting H2S synthesis. Ca(2+ chelator or Ca(2+ channel blocker attenuated NaHS-induced lateral root formation. Our study confirmed the role of H2S as a cellular signal in plants being a mediator between NO and Ca(2+ in regulating lateral root formation.

  18. The bifunctional abiotic stress signalling regulator and endogenous RNA silencing suppressor FIERY1 is required for lateral root formation

    KAUST Repository

    Chen, Hao

    2010-09-28

    The Arabidopsis FIERY1 (FRY1) locus was originally identified as a negative regulator of stress-responsive gene expression and later shown to be required for suppression of RNA silencing. In this study we discovered that the FRY1 locus also regulates lateral root formation. Compared with the wild type, fry1 mutant seedlings generated significantly fewer lateral roots under normal growth conditions and also exhibited a dramatically reduced sensitivity to auxin in inducing lateral root initiation. Using transgenic plants that overexpress a yeast homolog of FRY1 that possesses only the 3\\', 5\\'-bisphosphate nucleotidase activity but not the inositol 1-phosphatase activity, we demonstrated that the lateral root phenotypes in fry1 result from loss of the nucleotidase activity. Furthermore, a T-DNA insertion mutant of another RNA silencing suppressor, XRN4 (but not XRN2 or XRN3), which is an exoribonuclease that is inhibited by the substrate of the FRY1 3\\', 5\\'-bisphosphate nucleotidase, exhibits similar lateral root defects. Although fry1 and xrn4 exhibited reduced sensitivity to ethylene, our experiments demonstrated that restoration of ethylene sensitivity in the fry1 mutant is not sufficient to rescue the lateral root phenotypes of fry1. Our results indicate that RNA silencing modulated by FRY1 and XRN4 plays an important role in shaping root architecture. © 2010 Blackwell Publishing Ltd.

  19. Ethylene and nitric oxide interact to regulate the magnesium deficiency-induced root hair development in Arabidopsis.

    Science.gov (United States)

    Liu, Miao; Liu, Xing Xing; He, Xiao Lin; Liu, Li Juan; Wu, Hao; Tang, Cai Xian; Zhang, Yong Song; Jin, Chong Wei

    2017-02-01

    Nitric oxide (NO) and ethylene respond to biotic and abiotic stresses through either similar or independent processes. This study examines the mechanism underlying the effects of NO and ethylene on promoting root hair development in Arabidopsis under magnesium (Mg) deficiency. The interaction between NO and ethylene in the regulation of Mg deficiency-induced root hair development was investigated using NO- and ethylene-related mutants and pharmacological methods. Mg deficiency triggered a burst of NO and ethylene, accompanied by a stimulated development of root hairs. Interestingly, ethylene facilitated NO generation by activation of both nitrate reductase and nitric oxide synthase-like (NOS-L) in the roots of Mg-deficient plants. In turn, NO enhanced ethylene synthesis through stimulating the activities of 1-aminocyclopropane-1-carboxylate (ACC) oxidase and ACC synthase (ACS). These two processes constituted an NO-ethylene feedback loop. Blocking either of these two processes inhibited the stimulation of root hair development under Mg deficiency. In conclusion, we suggest that Mg deficiency increases the production of NO and ethylene in roots, each influencing the accumulation and role of the other, and thus these two signals interactively regulate Mg deficiency-induced root hair morphogenesis. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

  20. The secretion of organic acids is also regulated by factors other than aluminum.

    Science.gov (United States)

    Ding, Haiyan; Wen, Danni; Fu, Zhengwei; Qian, Haifeng

    2014-02-01

    As a result of natural processes and human activities, aluminum (Al) toxicity is recognized as a major limiting factor for plant productivity, and the secretion of organic acids facilitated by channel proteins is one of the most important Al resistance mechanisms in plants. The objective of this study was to evaluate the effects of several types of stress, including herbicide (imazethapyr (IM) and diclofop-methyl (DM)), heavy metal (Al and Cu), salt stress (NaCl), and proton stress (HCl), on the release of organic acids in rice. The results showed that 0.05 mg/L IM, 0.1 mg/L DM, 4680 mg/L NaCl, 0.5 mg/L CuSO4, and 18 mg/L AlCl3 significantly inhibited rice root elongation and the root fresh weight. In contrast, no significant inhibitory effects on rice growth were found with HCl (pH = 4.5). Similar to the effect of AlCl3 on organic acid induction, treatment with IM, DM, NaCl, and CuSO4 also induced the synthesis of endogenous citric acid and oxalic acid but decreased endogenous malic acid synthesis in the seedlings, though only citric acid was released into the environment after these treatments. We also analyzed the transcripts of three citrate channel proteins and found they were up-regulated by NaCl, CuSO4, and AlCl3 but not by IM or DM. This study clarified that organic acid secretion in plants might be a common phenomenon when plants are exposed to environmental stress other than Al toxicity.

  1. Mauritic acid: a new dammarane triterpene from the roots of Mauritia flexuosa L.f. (Arecaceae).

    Science.gov (United States)

    Koolen, Hector H F; Soares, Elzalina R; da Silva, Felipe M A; de Oliveira, Aimêe A; de Souza, Antonia Q L; de Medeiros, Lívia S; Rodrigues-Filho, Edson; Cavalcanti, Bruno C; Pessoa, Cláudia O; Moraes, Manoel O; Salvador, Marcos J; de Souza, Afonso D L

    2013-01-01

    A new dammarane triterpene named mauritic acid (1) was isolated from the roots of Mauritia flexuosa L.f. The complete structural assignment of this new compound was elucidated from spectroscopic methods. Moreover, this compound was evaluated for its cytotoxicity against human cancer cell lines (OVCAR-8, PCM3, NCIH358M and different leukaemia cell strains). The mauritic acid presented significant cytotoxicity against OVCAR-8, PCM3 and NCIH358M cell lines with IC50 3.02, 2.39 and 6.19 μM, respectively. The triterpenes 1 and 2 were also tested for their antimicrobial activity against 15 strains of microorganisms, including fungi and bacteria, with the best minimal inhibitory concentration values ranging from 50.8 to 203.5 μM.

  2. Effects of phenolic compounds on adventitious root formation and oxidative decarboxylation of applied indoleacetic acid in Malus 'Jork 9'

    NARCIS (Netherlands)

    Klerk, de G.J.M.; Guan, H.; Huisman, P.; Marinova, S.

    2011-01-01

    Stem slices (1-mm thick) cut from apple microshoots were cultured on a modified Murashige-Skoog medium with indole-3-acetic acid (IAA) or α-naphthaleneacetic acid (NAA), and increasing concentrations of various phenolic compounds. Both auxins were added at a concentration suboptimal for rooting. Ind

  3. Effects of phenolic compounds on adventitious root formation and oxidative decarboxylation of applied indoleacetic acid in Malus 'Jork 9'

    NARCIS (Netherlands)

    Klerk, de G.J.M.; Guan, H.; Huisman, P.; Marinova, S.

    2011-01-01

    Stem slices (1-mm thick) cut from apple microshoots were cultured on a modified Murashige-Skoog medium with indole-3-acetic acid (IAA) or α-naphthaleneacetic acid (NAA), and increasing concentrations of various phenolic compounds. Both auxins were added at a concentration suboptimal for rooting. Ind

  4. Low humic acids promote in vitro lily bulblet enlargement by enhancing roots growth and carbohydrate metabolism * #

    Science.gov (United States)

    Wu, Yun; Xia, Yi-ping; Zhang, Jia-ping; Du, Fang; Zhang, Lin; Ma, Yi-di; Zhou, Hong

    2016-01-01

    Bulblet development is a problem in global lily bulb production and carbohydrate metabolism is a crucial factor. Micropropagation acts as an efficient substitute for faster propagation and can provide a controllable condition to explore bulb growth. The present study was conducted to investigate the effects of humic acid (HA) on bulblet swelling and the carbohydrate metabolic pathway in Lilium Oriental Hybrids ‘Sorbonne’ under in vitro conditions. HA greatly promoted bulblet growth at 0.2, 2.0, and 20.0 mg/L, and pronounced increases in bulblet sucrose, total soluble sugar, and starch content were observed for higher HA concentrations (≥2.0 mg/L) within 45 d after transplanting (DAT). The activities of three major starch synthetic enzymes (including adenosine 5'-diphosphate glucose pyrophosphorylase, granule-bound starch synthase, and soluble starch synthase) were enhanced dramatically after HA application especially low concentration HA (LHA), indicating a quick response of starch metabolism. However, higher doses of HA also caused excessive aboveground biomass accumulation and inhibited root growth. Accordingly, an earlier carbon starvation emerged by observing evident starch degradation. Relative bulblet weight gradually decreased with increased HA doses and thereby broke the balance between the source and sink. A low HA concentration at 0.2 mg/L performed best in both root and bulblet growth. The number of roots and root length peaked at 14.5 and 5.75 cm, respectively. The fresh bulblet weight and diameter reached 468 mg (2.9 times that under the control treatment) and 11.68 mm, respectively. Further, sucrose/starch utilization and conversion were accelerated and carbon famine was delayed as a result with an average relative bulblet weight of 80.09%. To our knowledge, this is the first HA application and mechanism research into starch metabolism in both in vitro and in vivo condition in bulbous crops. PMID:27819136

  5. Response of Organic Acids to Zinc Homeostasis in Zinc-Deficient and Zinc-Toxic Apple Rootstock Roots

    Institute of Scientific and Technical Information of China (English)

    LIU Di; LIU Ai-Hong; HE Chen; WANG Jin-Hua; WANG Yan-An

    2012-01-01

    To elucidate the mechanisms of tolerance to zinc (Zn) deficiency and Zn toxicity in the root of apple trees,the apple rootstock Malus hupehensis (Pamp.) Rehd seedlings were selected to study the responses of organic acids to Zn homeostasis in roots under low Zn (0 μmol L-1),adequate Zn (as control,4 μmol L-1) and toxic Zn (100 μmol L-1) treatments.The differences of Zn concentrations and accumulations in the roots were highest,compared with those in the stems and leaves,when apple seedlings were subjected to low and toxic Zn treatments for 1 d.The concentrations and accumulations of oxalic and malic acids in the roots in the low and toxic Zn treatments increased by 20% to 60% compared with those of the control treatment.Significantly negative correlations were found between the total Zn concentrations and the concentrations of oxalic and malic acids in the roots under 1 d of low Zn treatment.However,contrary correlations were found for the toxic Zn treatment.Meanwhile,the maximum influx rates of Zn2+ under low and toxic Zn treatments increased by 30% and 20%,respectively,compared with the rate of the control treatment.Both Zn deficiency and Zn toxicity increased the concentrations of organic acids in root after short-time Zn treatment,which could resist Zn stress through balanding Zn homeostasis in M.hupehensis Rehd.

  6. Ethylene: a regulator of root architectural responses to soil phosphorus availability

    NARCIS (Netherlands)

    Borch, K.; Bouma, T.J.; Lynch, J.P.; Brown, K.M.

    1999-01-01

    The involvement of ethylene in root architectural responses to phosphorus availability was investigated in common bean (Phaseolus vulgaris L,) plants grown with sufficient and deficient phosphorus. Although phosphorus deficiency reduced root mass and lateral root number, main root length was unchang

  7. Ethylene: a regulator of root architectural responses to soil phosphorus availability

    NARCIS (Netherlands)

    Borch, K.; Bouma, T.J.; Lynch, J.P.; Brown, K.M.

    1999-01-01

    The involvement of ethylene in root architectural responses to phosphorus availability was investigated in common bean (Phaseolus vulgaris L,) plants grown with sufficient and deficient phosphorus. Although phosphorus deficiency reduced root mass and lateral root number, main root length was unchang

  8. GENETIC MODIFICATION OF GIBBERELLIC ACID SIGNALING TO PROMOTE CARBON SEQUESTRATION IN TREE ROOTS AND STEMS

    Energy Technology Data Exchange (ETDEWEB)

    Busov, Victor

    2013-03-05

    , flowering onset, floral structure, and vegetative phenology. Most transgenes elicited various levels of height reduction consistent with the roles of GA in elongation growth. Several other growth traits were proportionally reduced, including branch length, internode distance, and leaf length. In contrast to elongation growth, stem diameter growth was much less affected, suggesting that semi-dwarf trees in dense stands might provide high levels of biomass production and carbon sequestration. The severity of phenotypic effects was strongly correlated with transgene expression among independent transgenic events, but often in a non-linear manner, the form of which varied widely among constructs. The majority of semi-dwarfed, transgenic plants showed delayed bud flush and early bud set, and expression of a native GAI transgene accelerated first time flowering in the field. All of the phenotypic changes observed in multiple years were stable over the 3 years of field study. Our results suggest that transgenic modification of GA action may be useful for producing semi-dwarf trees with modified growth and morphology for horticulture and other uses. We studied the poplar C(19) gibberellin 2-oxidase (GA2ox) gene subfamily. We show that a set of paralogous gene pairs differentially regulate shoot and root development. ? PtGA2ox4 and its paralogous gene PtGA2ox5 are primarily expressed in aerial organs, and overexpression of PtGA2ox5 produced a strong dwarfing phenotype characteristic of GA deficiency. Suppression of PtGA2ox4 and PtGA2ox5 led to increased biomass growth, but had no effect on root development. By contrast, the PtGA2ox2 and PtGA2ox7 paralogous pair was predominantly expressed in roots, and when these two genes were RNAi-suppressed it led to a decrease of root biomass. ? The morphological changes in the transgenic plants were underpinned by tissue-specific increases in bioactive GAs that corresponded to the predominant native expression of the targeted paralogous gene

  9. GENETIC MODIFICATION OF GIBBERELLIC ACID SIGNALING TO PROMOTE CARBON SEQUESTRATION IN TREE ROOTS AND STEMS

    Energy Technology Data Exchange (ETDEWEB)

    Busov, Victor

    2013-03-05

    , flowering onset, floral structure, and vegetative phenology. Most transgenes elicited various levels of height reduction consistent with the roles of GA in elongation growth. Several other growth traits were proportionally reduced, including branch length, internode distance, and leaf length. In contrast to elongation growth, stem diameter growth was much less affected, suggesting that semi-dwarf trees in dense stands might provide high levels of biomass production and carbon sequestration. The severity of phenotypic effects was strongly correlated with transgene expression among independent transgenic events, but often in a non-linear manner, the form of which varied widely among constructs. The majority of semi-dwarfed, transgenic plants showed delayed bud flush and early bud set, and expression of a native GAI transgene accelerated first time flowering in the field. All of the phenotypic changes observed in multiple years were stable over the 3 years of field study. Our results suggest that transgenic modification of GA action may be useful for producing semi-dwarf trees with modified growth and morphology for horticulture and other uses. We studied the poplar C(19) gibberellin 2-oxidase (GA2ox) gene subfamily. We show that a set of paralogous gene pairs differentially regulate shoot and root development. ? PtGA2ox4 and its paralogous gene PtGA2ox5 are primarily expressed in aerial organs, and overexpression of PtGA2ox5 produced a strong dwarfing phenotype characteristic of GA deficiency. Suppression of PtGA2ox4 and PtGA2ox5 led to increased biomass growth, but had no effect on root development. By contrast, the PtGA2ox2 and PtGA2ox7 paralogous pair was predominantly expressed in roots, and when these two genes were RNAi-suppressed it led to a decrease of root biomass. ? The morphological changes in the transgenic plants were underpinned by tissue-specific increases in bioactive GAs that corresponded to the predominant native expression of the targeted paralogous gene

  10. Production and Metabolism of Indole Acetic Acid in Root Nodules and Symbiont (Rhizobium undicola Isolated from Root Nodule of Aquatic Medicinal Legume Neptunia oleracea Lour.

    Directory of Open Access Journals (Sweden)

    Pallab Kumar Ghosh

    2015-01-01

    Full Text Available Indole acetic acid is a phytohormone which plays a vital role in plant growth and development. The purpose of this study was to shed some light on the production of IAA in roots, nodules, and symbionts of an aquatic legume Neptunia oleracea and its possible role in nodular symbiosis. The symbiont (N37 was isolated from nodules of this plant and identified as Rhizobium undicola based on biochemical characteristics, 16S rDNA sequence homology, and DNA-DNA hybridization results. The root nodules were found to contain more IAA and tryptophan than root; however, no detectable amount of IAA was found in root. The IAA metabolizing enzymes IAA oxidase, IAA peroxidase (E.C.1.11.1.7, and polyphenol oxidase (E.C.1.14.18.1 were higher in root than nodule but total phenol and IAA content were reversed. The strain N37 was found to produce copious amount of IAA in YEM broth medium with tryptophan and reached its stationary phase at 20 h. An enrichment of the medium with mannitol, ammonium sulphate, B12, and 4-hydroxybenzaldehyde was found to promote the IAA production. The presence of IAA metabolizing enzymes and IAA production with PGPR traits including ACC deaminase activity of the symbionts was essential for plant microbe interaction and nodule function.

  11. Effect of plant growth regulators in the rooting of Pinus cuttings

    Directory of Open Access Journals (Sweden)

    Henrique Andréia

    2006-01-01

    Full Text Available This work evaluated the rooting of Pinus caribaea var. hondurensis Morelet cuttings under the action of different levels of plant growth regulators. The cuttings consisted of 4-6 cm long shoots of P. caribaea var. hondurensis Morelet with their basal needles removed. The basal part of the cuttings were treated for 2 seconds with the following treatments: 1- NAA 2000mg L-1; 2- NAA 4000mg L-1; 3- NAA 6000mg L-1; 4- NAA 2000mg L-1 + PBZ 100mg L-1; 5- NAA 4000mg L-1 + PBZ; 6- NAA 6000mg L-1 + PBZ; 7- IBA 2000mg L-1; 8- IBA 4000mg L-1; 9- IBA 6000mg L-1; 10-IBA 2000mg L-1 + PBZ; 11- IBA 4000mg L-1 + PBZ; 12- IBA 6000mg L-1 + PBZ; and a control. After receiving the treatment, the cuttings were planted in tubes containing 50% carbonized rice hulls and 50% vermiculite. The evaluations, performed 60 days after planting, showed that P. caribaea var. hondurensis cuttings treated with IBA produced a higher percentage of rooted cuttings than those treated with NAA; the most effective treatment was IBA 4000mg L-1 plus 100mg L-1 paclobutrazol.

  12. Biochemical changes in barberries during adventitious root formation: the role of indole-3-butyric acid and hydrogen peroxide

    Directory of Open Access Journals (Sweden)

    Ali Tehranifar

    2014-03-01

    Full Text Available Peroxidase, polyphenol oxidase (PPO, phenolic compounds and total sugars (TS were investigated during root formation in cuttings of Berberis vulgaris var. asperma (BVA and Berberis thunbergii var. atropurpurea (BTA treated with indole-3-butyric acid (IBA and IBA+H2O2. Rooting was observed on BTA cuttings but not on BVA cuttings. The BTA cuttings treated with IBA and IBA+H2O2 showed higher rooting percentages, number of roots, and root length over the control. Those treated with IBA+H2O2 recorded the lowest peroxidase activity after planting. BTA cuttings treated with IBA+H2O2 showed the highest peroxidase activity at 50 d after planting; BVA cuttings under different treatments showed no significant difference for peroxidase activity at planting time or up to 80 d after planting. PPO activity for the BTA cuttings in the control treatment was lower than for other treatments during root formation. The cuttings in the IBA and IBA+H2O2 treatments showed increased PPO activity from 0 to 50 d after planting and a slight decrease in PPO activity from 60 to 80 d after planting. PPO activity for the BVA cuttings was significantly lower than for BTA during root formation. The BTA cuttings treated with IBA and IBA+H2O2 showed the highest phenolic compound content during root formation. The BVA cuttings displayed higher TS than BTA during the initial stage of root formation. A comparison of the anatomical structure of easy-to-root and difficult-to-root cuttings indicated that physical inhibitors did not affect the rooting capacity of BVA.

  13. Identification of genes involved in indole-3-butyric acid-induced adventitious root formation in nodal cuttings of Camellia sinensis (L.) by suppression subtractive hybridization.

    Science.gov (United States)

    Wei, Kang; Wang, Liyuan; Cheng, Hao; Zhang, Chengcai; Ma, Chunlei; Zhang, Liqun; Gong, Wuyun; Wu, Liyun

    2013-02-10

    The plant hormone auxin plays a key role in adventitious rooting. To increase our understanding of genes involved in adventitious root formation, we identified transcripts differentially expressed in single nodal cuttings of Camellia sinensis treated with or without indole-3-butyric acid (IBA) by suppressive subtractive hybridization (SSH). A total of 77 differentially expressed transcripts, including 70 up-regulated and 7 down-regulated sequences, were identified in tea cuttings under IBA treatment. Seven candidate transcripts were selected and analyzed for their response to IBA, and IAA by real time RT-PCR. All these transcripts were up regulated by at least two folds one day after IBA treatment. Meanwhile, IAA showed less positive effects on the expression of candidate transcripts. The full-length cDNA of a F-box/kelch gene was also isolated and found to be similar to a group of At1g23390 like genes. These unigenes provided a new source for mining genes related to adventitious root formation, which facilitate our understanding of relative fundamental metabolism.

  14. Effect of indole-3-acetic acid on pea root growth, peroxidase profiles and hydroxyl radical formation

    Directory of Open Access Journals (Sweden)

    Kukavica Biljana

    2007-01-01

    Full Text Available Changes in growth, peroxidase profiles, and hydroxyl radical formation were examined in IAA (0.5-10 mg/l treated pea plants grown hydroponically and in isolated roots in liquid in vitro culture. IAA inhibited root elongation, both in hydroponically grown pea plants and in isolated roots in vitro. A remarkable increase in the number of POD iso­forms was noticed in isolated roots grown in vitro, compared to the roots from plants grown hydroponically. IAA induced both disappearance of several root POD isoforms and hydroxyl radical formation in the root and the root cell wall.

  15. Root-uptake of {sup 14}C derived from acetic acid and {sup 14}C transfer to rice edible parts

    Energy Technology Data Exchange (ETDEWEB)

    Ogiyama, Shinichi [Office of Biospheric Assessment for Waste Disposal, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba-shi 263-8555 (Japan)], E-mail: ogiyama@nirs.go.jp; Suzuki, Hiroyuki [Graduate School of Pharmaceutical Sciences, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba-shi 263-5522 (Japan); Inubushi, Kazuyuki [Graduate School of Horticulture, Chiba University, 648 Matsudo, Matsudo-shi 271-8510 (Japan); Takeda, Hiroshi; Uchida, Shigeo [Office of Biospheric Assessment for Waste Disposal, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba-shi 263-8555 (Japan)

    2010-02-15

    Three types of culture experiments using paddy rice (Oryza sativa L.) were performed to examine root-uptake of {sup 14}C in the form of acetic acid: double pot experiment (hydroponics), wet culture experiment (submerged sand medium), and chamber experiment (hydroponics and submerged sand medium). The {sup 14}C radioactivity in the plant, mediums, and atmospheric carbon dioxide ({sup 14}CO{sub 2}) in the chamber were determined, and the distribution of {sup 14}C in the plant was visualized using autoradiography. In the double pot experiment, the shoot of the plant and the lower root which was soaked in the culture solution had {sup 14}C radioactivity, but the upper root which did not have contact with the solution had none. There were also {sup 14}C radioactivity in the grains and roots in the wet culture experiment. Results of the chamber experiment showed that {sup 14}CO{sub 2} gas was released from the culture solution in both types of cultures. Results indicated that the {sup 14}C-acetic acid absorbed by rice plant through its root would be very small. Most of the {sup 14}C-acetic acid was transformed into gaseous forms either in the culture solution or rhizosphere. A relatively longer time would be needed to assimilate {sup 14}C derived from acetic acid to grain parts after it was once absorbed by the shoot through the root. Availability of {sup 14}C for the plant in sand culture was considered to be decreased compared with that for the plant in the hydroponics experiment. It was suggested that rice plant absorbed and assimilated {sup 14}C through the plant roots not because of uptake of {sup 14}C-acetic acid but because of uptake of {sup 14}C in gaseous forms such as {sup 14}CO{sub 2}.

  16. Transgenic analysis reveals LeACS-1 as a positive regulator of ethylene-induced shikonin biosynthesis in Lithospermum erythrorhizon hairy roots.

    Science.gov (United States)

    Fang, Rongjun; Wu, Fengyao; Zou, Ailan; Zhu, Yu; Zhao, Hua; Zhao, Hu; Liao, Yonghui; Tang, Ren-Jie; Yang, Tongyi; Pang, Yanjun; Wang, Xiaoming; Yang, Rongwu; Qi, Jinliang; Lu, Guihua; Yang, Yonghua

    2016-03-01

    The phytohormone ethylene (ET) is a crucial signaling molecule that induces the biosynthesis of shikonin and its derivatives in Lithospermum erythrorhizon shoot cultures. However, the molecular mechanism and the positive regulators involved in this physiological process are largely unknown. In this study, the function of LeACS-1, a key gene encoding the 1-aminocyclopropane-1-carboxylic acid synthase for ET biosynthesis in L. erythrorhizon hairy roots, was characterized by using overexpression and RNA interference (RNAi) strategies. The results showed that overexpression of LeACS-1 significantly increased endogenous ET concentration and shikonin production, consistent with the up-regulated genes involved in ET biosynthesis and transduction, as well as the genes related to shikonin biosynthesis. Conversely, RNAi of LeACS-1 effectively decreased endogenous ET concentration and shikonin production and down-regulated the expression level of above genes. Correlation analysis showed a significant positive linear relationship between ET concentration and shikonin production. All these results suggest that LeACS-1 acts as a positive regulator of ethylene-induced shikonin biosynthesis in L. erythrorhizon hairy roots. Our work not only gives new insights into the understanding of the relationship between ET and shikonin biosynthesis, but also provides an efficient genetic engineering target gene for secondary metabolite production in non-model plant L. erythrorhizon.

  17. Low pH, aluminum, and phosphorus coordinately regulate malate exudation through GmALMT1 to improve soybean adaptation to acid soils.

    Science.gov (United States)

    Liang, Cuiyue; Piñeros, Miguel A; Tian, Jiang; Yao, Zhufang; Sun, Lili; Liu, Jiping; Shaff, Jon; Coluccio, Alison; Kochian, Leon V; Liao, Hong

    2013-03-01

    Low pH, aluminum (Al) toxicity, and low phosphorus (P) often coexist and are heterogeneously distributed in acid soils. To date, the underlying mechanisms of crop adaptation to these multiple factors on acid soils remain poorly understood. In this study, we found that P addition to acid soils could stimulate Al tolerance, especially for the P-efficient genotype HN89. Subsequent hydroponic studies demonstrated that solution pH, Al, and P levels coordinately altered soybean (Glycine max) root growth and malate exudation. Interestingly, HN89 released more malate under conditions mimicking acid soils (low pH, +P, and +Al), suggesting that root malate exudation might be critical for soybean adaptation to both Al toxicity and P deficiency on acid soils. GmALMT1, a soybean malate transporter gene, was cloned from the Al-treated root tips of HN89. Like root malate exudation, GmALMT1 expression was also pH dependent, being suppressed by low pH but enhanced by Al plus P addition in roots of HN89. Quantitative real-time PCR, transient expression of a GmALMT1-yellow fluorescent protein chimera in Arabidopsis protoplasts, and electrophysiological analysis of Xenopus laevis oocytes expressing GmALMT1 demonstrated that GmALMT1 encodes a root cell plasma membrane transporter that mediates malate efflux in an extracellular pH-dependent and Al-independent manner. Overexpression of GmALMT1 in transgenic Arabidopsis, as well as overexpression and knockdown of GmALMT1 in transgenic soybean hairy roots, indicated that GmALMT1-mediated root malate efflux does underlie soybean Al tolerance. Taken together, our results suggest that malate exudation is an important component of soybean adaptation to acid soils and is coordinately regulated by three factors, pH, Al, and P, through the regulation of GmALMT1 expression and GmALMT1 function.

  18. Characterization of a calcium/calmodulin-dependent protein kinase homolog from maize roots showing light-regulated gravitropism

    Science.gov (United States)

    Lu, Y. T.; Hidaka, H.; Feldman, L. J.

    1996-01-01

    Roots of many species respond to gravity (gravitropism) and grow downward only if illuminated. This light-regulated root gravitropism is phytochrome-dependent, mediated by calcium, and inhibited by KN-93, a specific inhibitor of calcium/calmodulin-dependent protein kinase II (CaMK II). A cDNA encoding MCK1, a maize homolog of mammalian CaMK, has been isolated from roots of maize (Zea mays L.). The MCK1 gene is expressed in root tips, the site of perception for both light and gravity. Using the [35S]CaM gel-overlay assay we showed that calmodulin-binding activity of the MCK1 is abolished by 50 microM KN-93, but binding is not affected by 5 microM KN-93, paralleling physiological findings that light-regulated root gravitropism is inhibited by 50 microM KN-93, but not by 5 microM KN-93. KN-93 inhibits light-regulated gravitropism by interrupting transduction of the light signal, not light perception, suggesting that MCK1 may play a role in transducing light. This is the first report suggesting a physiological function for a CaMK homolog in light signal transduction.

  19. Differential Transcriptional Regulation in Roots of Tomato Near-Isogenic Lines in Response to Rapid-Onset Water Stress

    Science.gov (United States)

    Arms, Erin M.; Yan, Zhanghang; St.Clair, Dina A.

    2017-01-01

    Cultivated tomato (Solanum lycopersicum L.) is susceptible to abiotic stresses, including drought and chilling stress, while its wild relative (Solanum habrochaites) exhibits tolerance to many abiotic stresses. Chilling roots to 6°C induces rapid-onset water stress by impeding water movement from roots to shoots. Wild S. habrochaites responds to root chilling by closing stomata and maintaining shoot turgor, while cultivated tomato fails to close stomata and wilts. This phenotypic response (shoot turgor maintenance under root chilling) is controlled by a major QTL stm9 on chromosome 9 from S. habrochaites that was previously high-resolution mapped to a 0.32 cM region, but its effects on transcriptional regulation were unknown. Here we used paired near isogenic lines (NILs) differing only for the presence or absence of the S. habrochaites introgression containing stm9 in an otherwise S. lycopersicum background to investigate global transcriptional regulation in response to rapid-onset water stress induced by root chilling. NIL175 contains the S. habrochaites introgression and exhibits tolerance to root chilling stress, while NIL163 does not contain the introgression and is susceptible. RNA from roots of the two NILs was obtained at five time points during exposure to root chilling and mRNA-Seq performed. Differential expression analysis and hierarchical clustering of transcript levels were used to determine patterns of and changes in mRNA levels. Our results show that the transcriptional response of roots exposed to chilling stress is complex, with both overlapping and unique responses in tolerant and susceptible lines. In general, susceptible NIL 163 had a more complex transcriptional response to root chilling, while NIL175 exhibited a more targeted response to the imposed stress. Our evidence suggests that both the tolerant and susceptible NILs may be primed for response to root-chilling, with many of these response genes located on chromosome 9. Furthermore

  20. Postembryonic neuronal addition in Zebrafish dorsal root ganglia is regulated by Notch signaling

    Directory of Open Access Journals (Sweden)

    McGraw Hillary

    2012-06-01

    Full Text Available Abstract Background The sensory neurons and glia of the dorsal root ganglia (DRG arise from neural crest cells in the developing vertebrate embryo. In mouse and chick, DRG formation is completed during embryogenesis. In contrast, zebrafish continue to add neurons and glia to the DRG into adulthood, long after neural crest migration is complete. The molecular and cellular regulation of late DRG growth in the zebrafish remains to be characterized. Results In the present study, we use transgenic zebrafish lines to examine neuronal addition during postembryonic DRG growth. Neuronal addition is continuous over the period of larval development. Fate-mapping experiments support the hypothesis that new neurons are added from a population of resident, neural crest-derived progenitor cells. Conditional inhibition of Notch signaling was used to assess the role of this signaling pathway in neuronal addition. An increase in the number of DRG neurons is seen when Notch signaling is inhibited during both early and late larval development. Conclusions Postembryonic growth of the zebrafish DRG comes about, in part, by addition of new neurons from a resident progenitor population, a process regulated by Notch signaling.

  1. Systemic Regulation of Soybean Nodulation by Acidic Growth Conditions1[OA

    Science.gov (United States)

    Lin, Meng-Han; Gresshoff, Peter M.; Ferguson, Brett J.

    2012-01-01

    Mechanisms inhibiting legume nodulation by low soil pH, although highly prevalent and economically significant, are poorly understood. We addressed this in soybean (Glycine max) using a combination of physiological and genetic approaches. Split-root and grafting studies using an autoregulation-of-nodulation-deficient mutant line, altered in the autoregulation-of-nodulation receptor kinase GmNARK, determined that a systemic, shoot-controlled, and GmNARK-dependent mechanism was critical for facilitating the inhibitory effect. Acid inhibition was independent of aluminum ion concentration and occurred early in nodule development, between 12 and 96 h post inoculation with Bradyrhizobium japonicum. Biological effects were confirmed by measuring transcript numbers of known early nodulation genes. Transcripts decreased on both sides of split-root systems, where only one side was subjected to low-pH conditions. Our findings enhance the present understanding of the innate mechanisms regulating legume nodulation control under acidic conditions, which could benefit future attempts in agriculture to improve nodule development and biological nitrogen fixation in acid-stressed soils. PMID:23054568

  2. Analysis of soybean root proteins affected by gibberellic acid treatment under flooding stress.

    Science.gov (United States)

    Oh, Myeong Won; Nanjo, Yohei; Komatsu, Setsuko

    2014-01-01

    Flooding is a serious abiotic stress for soybean because it restricts growth and reduces grain yields. To investigate the effect of gibberellic acid (GA) on soybean under flooding stress, root proteins were analyzed using a gel-free proteomic technique. Proteins were extracted from the roots of 4-days-old soybean seedlings exposed to flooding stress in the presence and absence of exogenous GA3 for 2 days. A total of 307, 324, and 250 proteins were identified from untreated, and flooding-treated soybean seedlings without or with GA3, respectively. Secondary metabolism- and cell-related proteins, and proteins involved in protein degradation/synthesis were decreased by flooding stress; however, the levels of these proteins were restored by GA3 supplementation under flooding. Fermentation- and cell wall-related proteins were not affected by GA3 supplementation. Furthermore, putative GA-responsive proteins, which were identified by the presence of a GA-responsive element in the promoter region, were less abundant by flooding stress; however, these proteins were more abundant by GA3 supplementation under flooding. Taken together, these results suggest that GA3 affects the abundance of proteins involved in secondary metabolism, cell cycle, and protein degradation/synthesis in soybeans under flooding stress.

  3. ROOTING OF GUANANDI (Calophyllum brasiliense CAMBESS CUTTINGS USING INDOLE-BUTYRIC ACID

    Directory of Open Access Journals (Sweden)

    Eduardo Ciriello

    2015-12-01

    Full Text Available Commercial reforestation of Brazilian native species to produce hardwood for sawmills has been recently intensified in the country. Among the potential species planted by the logging industry is guanandi (Calophyllum brasiliense Cambess because it is widely distributed in the country, highly adapted to different soil and climate conditions, good bole form and high quality timber. The development of genetic improvement programs should prioritize gains in productivity and yields in the medium and long term. For such programs to be successful, the study of vegetative propagation techniques to abbreviate steps in forest improvement and allow its mass production is fundamental. To assess the viability of vegetative propagation of the species, two successive experiments were carried out during two years testing the best type of cutting, hormone concentration and management. Different cuttings types submitted to increasing doses of indole-butyric acid (IBA were tested to evaluate survival, sprouting, rooting and callus formation. Results indicate that the species is viable for vegetative propagation with 85 to 90% rooting of cuttings from seedlings in the IBA concentrations of 3000 to 7000 mg.L-1. For the cuttings, sprouting from the base of adult trees 3000 mg.L-1 was the best concentration of IBA.

  4. Root defense analysis against Fusarium oxysporum reveals new regulators to confer resistance

    OpenAIRE

    Chen, Yi Chung; Wong, Chin Lin; Muzzi, Frederico; Vlaardingerbroek, Ido; Kidd, Brendan N; Peer M Schenk

    2014-01-01

    Fusarium oxysporum is a root-infecting fungal pathogen that causes wilt disease on a broad range of plant species, including Arabidopsis thaliana. Investigation of the defense response against this pathogen had primarily been conducted using leaf tissue and little was known about the root defense response. In this study, we profiled the expression of root genes after infection with F. oxysporum by microarray analysis. In contrast to the leaf response, root tissue did not show a strong inducti...

  5. Apical microleakage of different root canal sealers after use of maleic acid and EDTA as final irrigants

    Directory of Open Access Journals (Sweden)

    Özgür İlke ULUSOY

    2014-01-01

    Full Text Available This study aimed to compare the effects of ethylenediaminetetraacetic acid (EDTA and maleic acid (MA on the sealing ability of various root canal sealers. Eighty root canals were instrumented and irrigated with either EDTA or MA. They were divided into eight experimental groups and obturated as follows: Group 1: MA + Hybrid Root SEAL/gutta-percha. Group 2: EDTA + Hybrid Root SEAL/gutta-percha. Group 3: MA + iRoot SP/gutta-percha. Group 4: EDTA + iRoot SP/gutta-percha. Group 5: MA + EndoREZ/EndoREZ points. Group 6: EDTA + EndoREZ/EndoREZ points. Group 7: MA + AH Plus/gutta-percha. Group 8: EDTA + AH Plus/gutta-percha. Another ten roots were used as negative and positive controls. The microleakage of each sample was measured at 2-min intervals for 8 min using the fluid filtration method. Data were statistically analyzed with one-way ANOVA, post-hoc Tukey, and paired-samples t tests. The minimum microleakage values were obtained from the teeth obturated with AH Plus and EndoREZ selaers (p < 0.001. The samples with Hybrid Root SEAL showed the maximum leakage (p < 0.001. There were significant differences between the groups irrigated with MA or EDTA in terms of microleakage (p < 0.05. Use of MA resulted in higher microleakage values compared with those using EDTA. The type of final irrigation solution seems to influence the postobturation apical seal. Use of AH Plus and EndoREZ sealers showed better sealing ability compared with IRoot SP and Hybrid Root SEAL.

  6. Role of Bile Acids and Bile Acid Receptors in Metabolic Regulation

    NARCIS (Netherlands)

    Lefebvre, Philippe; Cariou, Bertrand; Lien, Fleur; Kuipers, Folkert; Staels, Bart

    2009-01-01

    Lefebvre P, Cariou B, Lien F, Kuipers F, Staels B. Role of Bile Acids and Bile Acid Receptors in Metabolic Regulation. Physiol Rev 89: 147-191,2009; doi: 10.1152/physrev.00010.2008. - The incidence of the metabolic syndrome has taken epidemic proportions in the past decades, contributing to an incre

  7. GROWTH-REGULATING ACTIVITY OF SOME SALTS OF 1-NAPHTHALENACETIC ACID AND 2-NAPHTHOXYACETIC ACID

    Directory of Open Access Journals (Sweden)

    Maria Laichici

    2001-01-01

    Full Text Available The salts of 1-naphthalene acetic acid and 2-naphthoxyacetic acid with ethanolamine have been synthetized. The two salts have been assessed using Tsibulskaya-Vassiliev biological test using agar-agar as the medium. Statistical processing of the data has been carried out. The good results of the bioassay indicate an auxinic growth-regulating activity of the two salts.

  8. Localization of acid phosphatase activity in the apoplast of root nodules of pea (Pisum sativum

    Directory of Open Access Journals (Sweden)

    Marzena Sujkowska

    2011-01-01

    Full Text Available Changes in the activity of acid phosphatase (AcPase in the apoplast of pea root nodule were investigated. The activity was determined using lead and cerium methods. The results indicated a following sequence of AcPase activity appearance during the development of the infection thread: 1 low AcPase activity appears in the outer part of cells of symbiotic bacteria; 2 bacteria show increased AcPase activity, and the enzyme activity appears in the thread walls; 3 activity exhibits also matrix of the infection thread; 4 bacteria just before their release from the infection threads show high AcPase activity; 5 AcPase activity ceases after bacteria transformation into bacteroids. The increase in bacterial AcPase activity may reflect a higher demand for inorganic phosphorus necessary for propagation of the bacteria within the infection threads and/or involved in bacteria release from the infection threads.

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

    Science.gov (United States)

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

    2014-04-15

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

  10. Fluctuations of different endogenous phenolic compounds and cinnamic acid in the first days of the rooting process of cherry rootstock 'GiSelA 5' leafy cuttings.

    Science.gov (United States)

    Trobec, Mateja; Stampar, Franci; Veberic, Robert; Osterc, Gregor

    2005-05-01

    The relationship between the phenol composition of rooting zones and rootability was studied in the first days after the establishment of cuttings. The trial included two different types of cuttings (basal and terminal). Additionally, the influence of exogenously applied auxin (IBA) was observed. The best rooting results (55.6%) were achieved with terminal IBA treated cuttings, while only 1.9% of basal cuttings formed roots. The auxin treatment increased the root formation in terminal, but not in basal cuttings. Low rooting rate of basal cuttings was probably due to higher lignification rate of the basal tissue which can represent a mechanical barrier for root emergence. When measuring phenolic compounds and cinnamic acid, terminal cuttings contained higher (rutin, vanillic acid, (-)-epicatechin, caffeic acid and sinapinic acid) or equal concentrations of detected phenols as basal cuttings, while applied auxin did not influence the level of any of discussed phenolics, neither of cinnamic acid. It is to assume that cuttings for starting of root induction phase should contain certain levels of several phenolic compounds, but higher influence on rooting success is to be ascribed to the impact of the auxin level. During the time of the experiment concentrations of monophenols sinapinic acid and vanillic acid rapidly decreased. This decrease was more pronounced in terminal cuttings, which might have a better mechanism of lowering those two compounds to which a negative influence on rooting is ascribed. Fluctuations and differences between treatments of other phenolics were not significant enough to influence the rooting process.

  11. Regulated acid-base transport in the collecting duct.

    Science.gov (United States)

    Wagner, Carsten A; Devuyst, Olivier; Bourgeois, Soline; Mohebbi, Nilufar

    2009-05-01

    The renal collecting system serves the fine-tuning of renal acid-base secretion. Acid-secretory type-A intercalated cells secrete protons via a luminally expressed V-type H(+)-ATPase and generate new bicarbonate released by basolateral chloride/bicarbonate exchangers including the AE1 anion exchanger. Efficient proton secretion depends both on the presence of titratable acids (mainly phosphate) and the concomitant secretion of ammonia being titrated to ammonium. Collecting duct ammonium excretion requires the Rhesus protein RhCG as indicated by recent KO studies. Urinary acid secretion by type-A intercalated cells is strongly regulated by various factors among them acid-base status, angiotensin II and aldosterone, and the Calcium-sensing receptor. Moreover, urinary acidification by H(+)-ATPases is modulated indirectly by the activity of the epithelial sodium channel ENaC. Bicarbonate secretion is achieved by non-type-A intercalated cells characterized by the luminal expression of the chloride/bicarbonate exchanger pendrin. Pendrin activity is driven by H(+)-ATPases and may serve both bicarbonate excretion and chloride reabsorption. The activity and expression of pendrin is regulated by different factors including acid-base status, chloride delivery, and angiotensin II and may play a role in NaCl retention and blood pressure regulation. Finally, the relative abundance of type-A and non-type-A intercalated cells may be tightly regulated. Dysregulation of intercalated cell function or abundance causes various syndromes of distal renal tubular acidosis underlining the importance of these processes for acid-base homeostasis.

  12. Ag+ as a More Effective Elicitor for Production of Tanshinones than Phenolic Acids in Salvia miltiorrhiza Hairy Roots

    Directory of Open Access Journals (Sweden)

    Bingcong Xing

    2014-12-01

    Full Text Available Phenolic acids and tanshinones are two groups of bioactive ingredients in Salvia miltiorrhiza Bunge. As a heavy metal elicitor, it has been reported that Ag+ can induce accumulations of both phenolic acids and tanshinones in S. miltiorrhiza hairy roots. In this study, the effects of Ag+ treatment on accumulations of six phenolic acids and four tanshinones in S. miltiorrhiza hairy roots were investigated. To further elucidate the molecular mechanism, expressions of key genes involved in the biosynthesis of these ingredients were also detected. The results showed that although the total phenolic acids content was almost not affected by Ag+, accumulations of rosmarinic acid (RA, caffeic acid and ferulic acid were significantly increased, while accumulations of salvianolic acid B (LAB, danshensu (DSU and cinnamic acid were decreased. We speculate that LAB probably derived from the branch pathway of DSU biosynthesis. Contents of four tanshinones were enhanced by Ag+ and their accumulations were more sensitive to Ag+ than phenolic acids. Genes in the upstream biosynthetic pathways of these ingredients responded to Ag+ earlier than those in the downstream biosynthetic pathways. Ag+ probably induced the whole pathways, upregulated gene expressions from the upstream pathways to the downstream pathways, and finally resulted in the enhancement of ingredient production. Compared with phenolic acids, tanshinone production was more sensitive to Ag+ treatments. This study will help us understand how secondary metabolism in S. miltiorrhiza responds to elicitors and provide a reference for the improvement of the production of targeted compounds in the near future.

  13. Ag+ as a more effective elicitor for production of tanshinones than phenolic acids in Salvia miltiorrhiza hairy roots.

    Science.gov (United States)

    Xing, Bingcong; Yang, Dongfeng; Guo, Wanli; Liang, Zongsuo; Yan, Xijun; Zhu, Yonghong; Liu, Yan

    2014-12-24

    Phenolic acids and tanshinones are two groups of bioactive ingredients in Salvia miltiorrhiza Bunge. As a heavy metal elicitor, it has been reported that Ag+ can induce accumulations of both phenolic acids and tanshinones in S. miltiorrhiza hairy roots. In this study, the effects of Ag+ treatment on accumulations of six phenolic acids and four tanshinones in S. miltiorrhiza hairy roots were investigated. To further elucidate the molecular mechanism, expressions of key genes involved in the biosynthesis of these ingredients were also detected. The results showed that although the total phenolic acids content was almost not affected by Ag+, accumulations of rosmarinic acid (RA), caffeic acid and ferulic acid were significantly increased, while accumulations of salvianolic acid B (LAB), danshensu (DSU) and cinnamic acid were decreased. We speculate that LAB probably derived from the branch pathway of DSU biosynthesis. Contents of four tanshinones were enhanced by Ag+ and their accumulations were more sensitive to Ag+ than phenolic acids. Genes in the upstream biosynthetic pathways of these ingredients responded to Ag+ earlier than those in the downstream biosynthetic pathways. Ag+ probably induced the whole pathways, upregulated gene expressions from the upstream pathways to the downstream pathways, and finally resulted in the enhancement of ingredient production. Compared with phenolic acids, tanshinone production was more sensitive to Ag+ treatments. This study will help us understand how secondary metabolism in S. miltiorrhiza responds to elicitors and provide a reference for the improvement of the production of targeted compounds in the near future.

  14. Comparative assessment of fluorosed and nonfluorosed fibroblast attachment on fluorosed and nonfluorosed teeth after scaling and root planning and ethylenediaminetetraacetic acid root biomodification

    Directory of Open Access Journals (Sweden)

    Kharidi Laxman Vandana

    2014-01-01

    Full Text Available Background and Objectives: Fluorosis causes mineralization changes in the tooth and can lead to morphological alterations of fibroblasts. To evaluate the effect of fluorosis on periodontal healing, the initial step while healing such as, fibroblast attachment onto the root surface requires to be evaluated on the fluorosed and nonfluorosed tooth using nonfluorosed as well as fluorosed fibroblasts originated from the subjects influenced by high-water fluoride. Hence, the objective of the current study was to study and compare the attachment of nonfluorosed and fluorosed fibroblasts on the fluorosed and nonfluorosed root fragments. Materials and Methods: A total of 112 fluorosed and nonfluorosed, periodontally healthy and diseased tooth roots were obtained and allotted to eight groups : f0 luorosed healthy (FH and non-FH (NFH controls, fluorosed diseased (FD and non-FD (NFD controls, fluorosed and nonfluorosed teeth treated with scaling and root planning (SRP (FD SRP and NFD SRP and similar groups treated with SRP and ethylenediaminetetraacetic acid (EDTA (FD SRP + EDTA and NFD SRP + EDTA burnishing treatment with 24% EDTA gel for 2 min. After the respective treatment half of the root fragments in each group were incubated in the human periodontal ligament fibroblast cells obtained and cultured from freshly extracted FH and NFH human premolar tooth root. The nonfluorosed fibroblasts are elongated, flat cells thus they show increased attachment to root the surface. Results: When comparison was carried out between the attachment of fluorosed and nonfluorosed fibroblasts on NFD groups treated with scaling and EDTA, significant results were obtained with increased attachment seen on the group incubated with nonfluorosed fibroblasts (P = 0.029. While on comparison between the attachment of fluorosed and nonfluorosed fibroblasts on NFH group, NFD group treated with SRP and NFD group, no significant results were obtained (P > 0.05. On comparison between

  15. Plant-specific Histone Deacetylases HDT½ Regulate GIBBERELLIN 2-OXIDASE 2 Expression to Control Arabidopsis Root Meristem Cell Number.

    Science.gov (United States)

    Li, Huchen; Torres-Garcia, Jesus; Latrasse, David; Benhamed, Moussa; Schilderink, Stefan; Zhou, Wenkun; Kulikova, Olga; Hirt, Heribert; Bisseling, Ton

    2017-08-30

    Root growth is modulated by environmental factors and depends on cell production in the root meristem (RM). New cells in the meristem are generated by stem cells and transit-amplifying cells, which together determine RM cell number. Transcription factors and chromatin-remodelling factors have been implicated in regulating the switch from stem cells to transit-amplifying cells. Here we show that two Arabidopsis thaliana paralogs encoding plant-specific histone deacetylases, HDT1 and HDT2, regulate a second switch from transit-amplifying cells to expanding cells. Knockdown of HDT½ (hdt1,2i) results in an earlier switch and causes a reduced RM cell number. Our data show that HDT½ negatively regulate the acetylation level of the C19-GIBBERELLIN 2-OXIDASE 2 (GA2ox2) locus and repress the expression of GA2ox2 in the RM and elongation zone. Overexpression of GA2ox2 in the RM phenocopies the hdt1,2i phenotype. Conversely, knockout of GA2ox2 partially rescues the root growth defect of hdt1,2i. These results suggest that by repressing the expression of GA2ox2, HDT½ likely fine-tune gibberellin metabolism and they are crucial for regulating the switch from cell division to expansion to determine RM cell number. We propose that HDT½ function as part of a mechanism that modulates root growth in response to environmental factors. © 2017 American Society of Plant Biologists. All rights reserved.

  16. Plant-specific Histone Deacetylases HDT½ Regulate GIBBERELLIN 2-OXIDASE 2 Expression to Control Arabidopsis Root Meristem Cell Number

    KAUST Repository

    Li, Huchen

    2017-08-31

    Root growth is modulated by environmental factors and depends on cell production in the root meristem (RM). New cells in the meristem are generated by stem cells and transit-amplifying cells, which together determine RM cell number. Transcription factors and chromatin-remodelling factors have been implicated in regulating the switch from stem cells to transit-amplifying cells. Here we show that two Arabidopsis thaliana paralogs encoding plant-specific histone deacetylases, HDT1 and HDT2, regulate a second switch from transit-amplifying cells to expanding cells. Knockdown of HDT½ (hdt1,2i) results in an earlier switch and causes a reduced RM cell number. Our data show that HDT½ negatively regulate the acetylation level of the C19-GIBBERELLIN 2-OXIDASE 2 (GA2ox2) locus and repress the expression of GA2ox2 in the RM and elongation zone. Overexpression of GA2ox2 in the RM phenocopies the hdt1,2i phenotype. Conversely, knockout of GA2ox2 partially rescues the root growth defect of hdt1,2i. These results suggest that by repressing the expression of GA2ox2, HDT½ likely fine-tune gibberellin metabolism and they are crucial for regulating the switch from cell division to expansion to determine RM cell number. We propose that HDT½ function as part of a mechanism that modulates root growth in response to environmental factors.

  17. Comparison of the efficacy of ethylenediaminetetraacetic acid and tetracycline hydrochloride as root conditioning agents: An in vitro study

    Directory of Open Access Journals (Sweden)

    Tarun Nanda

    2012-01-01

    Full Text Available Objective: Root surfaces of periodontitis-affected teeth are hypermineralized and contaminated with cytotoxic and other biologically active substances. Various root conditioning agents have been recommended as an adjunct to mechanical root surface debridement to expose dentin collagen and cementum bound proteins. The aim of the present in vitro study was to compare the efficacy of ethylenediaminetetraacetic acid (EDTA and tetracycline hydrochloride (HCl as root conditioning agents on planed root surfaces. Materials and Methods: A total of 20 human maxillary anterior teeth indicated for extraction due to chronic periodontitis were collected and root planed. The teeth were sectioned and specimens were divided into two groups - Group I and II. Group I dentin specimens were treated with EDTA and Group II specimens were treated with tetracycline HCl solution at a concentration of 10% by active burnishing technique for 3 min. The root surface samples were then examined by scanning electron microscope. Results: The results of this study showed that EDTA and tetracycline HCl were equally effective in removing the smear layer. It was observed that the total and patent dentinal tubules were more in number in teeth treated with tetracycline when compared to EDTA group. However, EDTA was found to be much more effective as root conditioning agent because it enlarged the diameter of dentinal tubules more than that of tetracycline HCl. Conclusion: The results of in vitro study showed that both the agents are good root conditioning agents if applied in addition to periodontal therapy. However, further studies are required to establish the in vivo importance of EDTA and tetracycline HCL as root conditioners.

  18. Linking development and determinacy with organic acid efflux from proteoid roots of white lupin grown with low phosphorus and ambient or elevated atmospheric CO{sub 2} concentration

    Energy Technology Data Exchange (ETDEWEB)

    Watt, M.; Evans, J.R.

    1999-07-01

    White lupin (Lupinus albus L.) was grown in hydroponic culture with 1 {micro}M phosphorus to enable the development of proteoid roots to be observed in conjunction with organic acid exudation. Discrete regions of closely spaced, determinate secondary laterals emerged in near synchrony on the same plant. One day after reaching their final length, citrate exudation occurred over a 3-d pulse. The rate of exudation varied diurnally, with maximal rates during the photoperiod. At the onset of citrate efflux, rootlets had exhausted their apical meristems and had differentiated root hairs and vascular tissues along their lengths. Neither in vitro phosphoenolpyruvate carboxylase nor citrate synthase activity was correlated with the rate of citrate exudation. The authors suggest that an unidentified transport process, presumably at the plasma membrane, regulates citrate efflux. Growth with elevated atmospheric [CO{sub 2}] promoted earlier onset of rootlet determinacy by 1 d, resulting in shorter rootlets and citrate export beginning 1 d earlier as a 2-d diurnal pulse. Citrate was the dominant organic acid exported, and neither the rate of exudation per unit length of root nor the composition of exudate was altered by atmospheric [CO{sub 2}].

  19. Transcriptional regulation of central amino acid metabolism in Lactococcus lactis

    NARCIS (Netherlands)

    Larsen, Rasmus

    2005-01-01

    This thesis describes the functional characterisation of the transcriptional regulators GlnR, ArgR and AhrC of Lactococcus lactis, which are responsible for the control of genes involved in the metabolism of the amino acids glutamine, glutamate and arginine. A chromosomal glnR deletion mutant was ma

  20. Effect of cadmium on germination, coleoptile and root growth of barley seeds in the presence of gibberellic acid and kinetin.

    Science.gov (United States)

    Munzuroglu, Omer; Zengin, Fikriye Kirbag

    2006-10-01

    Effect of cadmium on barley seeds treated with kinetin and gibberellic acid was investigated. As usual, cadmium has inhibited seed germination, and showed important inhibitory effects on roots and coleoptile growth after germination. In general, increase in cadmium concentration caused a greater inhibition of germination, root and coleoptile growth. The adverse effect of cadmium on root and coleoptile growth was more pronounced than that on germination. While testa was pierced by radicle (an indication of germination), no root or coleoptile development was observed above at concentration of 3-9.5 mM CdCl2xH2O. Low concentrations of cadmium have inhibited the root growth more than it did on coleoptile growth. Treatment of seeds with gibberellic acid and kinetin did not show any significant difference on the effect of cadmium in germination. However, inhibition of coleoptile elongation by cadmium has decreased a very much after kinetin application. The same result, although with lower rates when compared to kinetin, has been obtained for GA3 as well. In addition, the inhibitory effect of cadmium on root growth increased even more after kinetin application. The results have been found statistically significant through the least significant different (LSD) test at levels ofp < 0.05 and p < 0.01.

  1. Jasmonic acid causes short- and long-term alterations to the transcriptome and the expression of defense genes in sugarbeet roots

    Science.gov (United States)

    Jasmonic acid (JA) induces native defense responses in plants and increases the resistance of postharvest sugarbeet roots to three common storage-rot causing organisms. To gain insight into the defense responses induced by JA in harvested sugarbeet roots, RNA was isolated from roots treated with wat...

  2. Auxin, ethylene and the regulation of root growth under mechanical impedance

    Science.gov (United States)

    Sharma, Rameshwar; Santisree, Parankusam; Nongmaithem, Sapana; Sreelakshmi, Yellamaraju

    2012-07-01

    Among the multitude functions performed by plant roots, little information is available about the mechanisms that allow roots to overcome the soil resistance, in order to grow in the soil to obtain water and nutrient. Tomato (Solanum lycopersicum) seedlings grown on horizontally placed agar plates showed a progressive decline in the root length with the increasing impedance of agar media. The incubation with 1-methylcyclopropane (1-MCP), an inhibitor of ethylene perception, led to aerial growth of roots. In contrast, in absence of 1-MCP control roots grew horizontally anchored to the agar surface. Though 1-MCP-treated and control seedlings showed differential ability to penetrate in the agar, the inhibition of root elongation was nearly similar for both treatments. While increased mechanical impedance also progressively impaired hypocotyl elongation in 1-MCP treated seedlings, it did not affect the hypocotyl length of control seedlings. The decline in root elongation was also associated with increased expression of DR5::GUS activity in the root tip signifying accumulation of auxin at the root tip. The increased expression of DR5::GUS activity in the root tip was also observed in 1-MCP treated seedlings, indicating independence of this response from ethylene signaling. Our results indicate operation of a sensing mechanism in root that likely operates independently of ethylene but involves auxin to determine the degree of impedance of the substratum.

  3. Cannabinoids inhibit acid-sensing ion channel currents in rat dorsal root ganglion neurons.

    Directory of Open Access Journals (Sweden)

    Yu-Qiang Liu

    Full Text Available Local acidosis has been found in various pain-generating conditions such as inflammation and tissue injury. Cannabinoids exert a powerful inhibitory control over pain initiation via peripheral cognate receptors. However, the peripheral molecular targets responsible for the antinociceptive effects of cannabinoids are still poorly understood. Here, we have found that WIN55,212-2, a cannabinoid receptor agonist, inhibits the activity of native acid-sensing ion channels (ASICs in rat dorsal root ganglion (DRG neurons. WIN55,212-2 dose-dependently inhibited proton-gated currents mediated by ASICs. WIN55,212-2 shifted the proton concentration-response curve downwards, with an decrease of 48.6±3.7% in the maximum current response but with no significant change in the EC(50 value. The inhibition of proton-gated current induced by WIN55,212-2 was almost completely blocked by the selective CB1 receptor antagonist AM 281, but not by the CB2 receptor antagonist AM630. Pretreatment of forskolin, an AC activator, and the addition of cAMP also reversed the inhibition of WIN55,212-2. Moreover, WIN55,212-2 altered acid-evoked excitability of rat DRG neurons and decreased the number of action potentials induced by acid stimuli. Finally, WIN55,212-2 attenuated nociceptive responses to injection of acetic acid in rats. These results suggest that WIN55,212-2 inhibits the activity of ASICs via CB1 receptor and cAMP dependent pathway in rat primary sensory neurons. Thus, cannabinoids can exert their analgesic action by interaction with ASICs in the primary afferent neurons, which was novel analgesic mechanism of cannabinoids.

  4. Identification of beer bitter acids regulating mechanisms of gastric acid secretion.

    Science.gov (United States)

    Walker, Jessica; Hell, Johannes; Liszt, Kathrin I; Dresel, Michael; Pignitter, Marc; Hofmann, Thomas; Somoza, Veronika

    2012-02-15

    Beer, one of the most consumed beverages worldwide, has been shown to stimulate gastric acid secretion. Although organic acids, formed by fermentation of glucose, are known to be stimulants of gastric acid secretion, very little is known about the effects of different types of beer or the active constituents thereof. In the present study, we compared the effects of different beers on mechanisms of gastric acid secretion. To investigate compound-specific effects on mechanisms of gastric acid secretion, organic acids and bitter compounds were quantified by HPLC-DAD and UPLC-MS/MS and tested in human gastric cancer cells (HGT-1) by means of a pH-sensitive fluorescent dye which determines the intracellular pH as an indicator of proton secretion. The expression of relevant genes, coding the H(+)/K(+)-ATPase, ATP4A, the histamine receptor, HRH2, the acetylcholine receptor, CHRM3, and the somatostatin receptor, SSTR2, was determined by qPCR. Ethanol and the organic acids succinic acid, malic acid, and citric acid were demonstrated to contribute to some extent to the effect of beer. The bitter acids comprising α-, β-, and iso-α-acids were identified as potential key components promoting gastric acid secretion and up-regulation of CHRM3 gene expression by a maximum factor of 2.01 compared to that of untreated control cells with a correlation to their respective bitterness.

  5. Transient Influx of Nickel in Root Mitochondria Modulates Organic Acid and Reactive Oxygen Species Production in Nickel Hyperaccumulator Alyssum murale*

    Science.gov (United States)

    Agrawal, Bhavana; Czymmek, Kirk J.; Sparks, Donald L.; Bais, Harsh P.

    2013-01-01

    Mitochondria are important targets of metal toxicity and are also vital for maintaining metal homeostasis. Here, we examined the potential role of mitochondria in homeostasis of nickel in the roots of nickel hyperaccumulator plant Alyssum murale. We evaluated the biochemical basis of nickel tolerance by comparing the role of mitochondria in closely related nickel hyperaccumulator A. murale and non-accumulator Alyssum montanum. Evidence is presented for the rapid and transient influx of nickel in root mitochondria of nickel hyperaccumulator A. murale. In an early response to nickel treatment, substantial nickel influx was observed in mitochondria prior to sequestration in vacuoles in the roots of hyperaccumulator A. murale compared with non-accumulator A. montanum. In addition, the mitochondrial Krebs cycle was modulated to increase synthesis of malic acid and citric acid involvement in nickel hyperaccumulation. Furthermore, malic acid, which is reported to form a complex with nickel in hyperaccumulators, was also found to reduce the reactive oxygen species generation induced by nickel. We propose that the interaction of nickel with mitochondria is imperative in the early steps of nickel uptake in nickel hyperaccumulator plants. Initial uptake of nickel in roots results in biochemical responses in the root mitochondria indicating its vital role in homeostasis of nickel ions in hyperaccumulation. PMID:23322782

  6. Transient Influx of nickel in root mitochondria modulates organic acid and reactive oxygen species production in nickel hyperaccumulator Alyssum murale.

    Science.gov (United States)

    Agrawal, Bhavana; Czymmek, Kirk J; Sparks, Donald L; Bais, Harsh P

    2013-03-08

    Mitochondria are important targets of metal toxicity and are also vital for maintaining metal homeostasis. Here, we examined the potential role of mitochondria in homeostasis of nickel in the roots of nickel hyperaccumulator plant Alyssum murale. We evaluated the biochemical basis of nickel tolerance by comparing the role of mitochondria in closely related nickel hyperaccumulator A. murale and non-accumulator Alyssum montanum. Evidence is presented for the rapid and transient influx of nickel in root mitochondria of nickel hyperaccumulator A. murale. In an early response to nickel treatment, substantial nickel influx was observed in mitochondria prior to sequestration in vacuoles in the roots of hyperaccumulator A. murale compared with non-accumulator A. montanum. In addition, the mitochondrial Krebs cycle was modulated to increase synthesis of malic acid and citric acid involvement in nickel hyperaccumulation. Furthermore, malic acid, which is reported to form a complex with nickel in hyperaccumulators, was also found to reduce the reactive oxygen species generation induced by nickel. We propose that the interaction of nickel with mitochondria is imperative in the early steps of nickel uptake in nickel hyperaccumulator plants. Initial uptake of nickel in roots results in biochemical responses in the root mitochondria indicating its vital role in homeostasis of nickel ions in hyperaccumulation.

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

    Science.gov (United States)

    Moore, R.; Smith, J. D.

    1985-01-01

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

  8. Differential regulation of placental amino acid transport by saturated and unsaturated fatty acids.

    Science.gov (United States)

    Lager, Susanne; Jansson, Thomas; Powell, Theresa L

    2014-10-15

    Fatty acids are critical for normal fetal development but may also influence placental function. We have previously reported that oleic acid (OA) stimulates amino acid transport in primary human trophoblasts (PHTs). In other tissues, saturated and unsaturated fatty acids have distinct effects on cellular signaling, for instance, palmitic acid (PA) but not OA reduces IκBα expression. We hypothesized that saturated and unsaturated fatty acids differentially affect trophoblast amino acid transport and cellular signaling. To test this hypothesis, PHTs were cultured in docosahexaenoic acid (DHA; 50 μM), OA (100 μM), or PA (100 μM). DHA and OA were also combined to test whether DHA could counteract the OA stimulatory effect on amino acid transport. The effects of fatty acids were compared against a vehicle control. Amino acid transport was measured by isotope-labeled tracers. Activation of inflammatory-related signaling pathways and the mechanistic target of rapamycin (mTOR) pathway were determined by Western blot analysis. Exposure of PHTs to DHA for 24 h reduced amino acid transport and phosphorylation of p38 MAPK, STAT3, mTOR, eukaryotic initiation factor 4E-binding protein 1, and ribosomal protein (rp)S6. In contrast, OA increased amino acid transport and phosphorylation of ERK, mTOR, S6 kinase 1, and rpS6. The combination of DHA with OA increased amino acid transport and rpS6 phosphorylation. PA did not affect amino acid transport but reduced IκBα expression. In conclusion, these fatty acids differentially regulated placental amino acid transport and cellular signaling. Taken together, these findings suggest that dietary fatty acids could alter the intrauterine environment by modifying placental function, thereby having long-lasting effects on the developing fetus.

  9. Nitric oxide alleviates aluminum-induced oxidative damage through regulating the ascorbate-glutathione cycle in roots of wheat

    Institute of Scientific and Technical Information of China (English)

    Chengliang Sun; Lijuan Liu; Yan Yu; Wenjing Liu; Lingli Lu; Chongwei Jin; Xianyong Lin

    2015-01-01

    The possible association with nitric oxide (NO) and ascorbate-glutathione (AsA-GSH) cycle in regulating aluminum (Al) tolerance of wheat (Triticum aestivum L.) was investigated using two genotypes with different Al resistance. Exposure to Al inhibited root elongation, and triggered lipid peroxidation and oxidation of AsA to dehydroascorbate and GSH to glutathione disulfide in wheat roots. Exogenous NO significantly increased endogenous NO levels, and subsequently al eviated Al-induced inhibition of root elongation and oxidation of AsA and GSH to maintain the redox molecules in the reduced form in both wheat genotypes. Under Al stress, significantly increased activities and gene transcriptional levels of ascorbate peroxi-dase, glutathione reductase, and dehydroascorbate reductase, were observed in the root tips of the Al-tolerant genotype Jian-864. Nitric oxide application enhanced the activity and gene transcriptional level of these enzymes in both wheat geno-types. g-Glutamylcysteine synthetase was not significantly affected by Al or NO, but NO treatments increased the activity of glutathione peroxidase and glutathione S-transferase to a greater extent than the Al-treated wheat seedlings. Proline was significantly decreased by Al, while it was not affected by NO. These results clearly suggest that NO protects wheat root against Al-induced oxidative stress, possibly through its regulation of the AsA-GSH cycle.

  10. The Medicago truncatula CRE1 cytokinin receptor regulates lateral root development and early symbiotic interaction with Sinorhizobium meliloti.

    Science.gov (United States)

    Gonzalez-Rizzo, Silvina; Crespi, Martin; Frugier, Florian

    2006-10-01

    Legumes develop different types of lateral organs from their primary root, lateral roots and nodules, the latter depending on a symbiotic interaction with Sinorhizobium meliloti. Phytohormones have been shown to function in the control of these organogeneses. However, related signaling pathways have not been identified in legumes. We cloned and characterized the expression of Medicago truncatula genes encoding members of cytokinin signaling pathways. RNA interference of the cytokinin receptor homolog Cytokinin Response1 (Mt CRE1) led to cytokinin-insensitive roots, which showed an increased number of lateral roots and a strong reduction in nodulation. Both the progression of S. meliloti infection and nodule primordia formation were affected. We also identified two cytokinin signaling response regulator genes, Mt RR1 and Mt RR4, which are induced early during the symbiotic interaction. Induction of these genes by S. meliloti infection is altered in mutants affected in the Nod factor signaling pathway; conversely, cytokinin regulation of the early nodulin Nodule Inception1 (Mt NIN) depends on Mt CRE1. Hence, cytokinin signaling mediated by a single receptor, Mt CRE1, leads to an opposite control of symbiotic nodule and lateral root organogenesis. Mt NIN, Mt RR1, and Mt RR4 define a common pathway activated during early S. meliloti interaction, allowing crosstalk between plant cytokinins and bacterial Nod factors signals.

  11. Diterpenoid Tanshinones and Phenolic Acids from Cultured Hairy Roots of Salvia miltiorrhiza Bunge and Their Antimicrobial Activities

    Directory of Open Access Journals (Sweden)

    Peiqin Li

    2011-03-01

    Full Text Available Four diterpenoid tanshinones and three phenolic acids were isolated from the crude ethanol extract of the cultured hairy roots of Salvia miltiorrhiza Bunge by bioassay-guided fractionation. By means of physicochemical and spectrometric analysis, they were identified as tanshinone ΙΙA (1, tanshinone Ι (2, cryptotanshinone (3, dihydrotanshinone Ι (4, rosmarinic acid (5, caffeic acid (6, and danshensu (7. These compounds were evaluated to show a broad antimicrobial spectrum of activity on test microorganisms including eight bacterial and one fungal species. Among the four tanshinones, cryptotanshinone (3 and dihydrotanshinone Ι (4 exhibited stronger antimicrobial activity than tanshinone ΙΙA (1 and tanshinone Ι (2. The results indicated that the major portion of the antimicrobial activity was due to the presence of tanshinones and phenolic acids in S. miltiorrhiza hairy roots, which could be used as the materials for producing antimicrobial agents for use in agricultural practice in the future.

  12. Comparative Transcriptome Analysis Reveal Candidate Genes Potentially Involved in Regulation of Primocane Apex Rooting in Raspberry (Rubus spp.

    Directory of Open Access Journals (Sweden)

    Jianfeng Liu

    2017-06-01

    Full Text Available Raspberries (Rubus spp. exhibit a unique rooting process that is initiated from the stem apex of primocane, conferring an unusual asexual mode of reproduction to this plant. However, the full complement of genes involved in this process has not been identified. To this end, the present study analyzed the transcriptomes of the Rubus primocane and floricane stem apex at three developmental stages by Digital Gene Expression profiling to identify genes that regulate rooting. Sequencing and de novo assembly yielded 26.82 Gb of nucleotides and 59,173 unigenes; 498, 7,346, 4,110, 7,900, 9,397, and 4,776 differently expressed genes were identified in paired comparisons of SAF1 (floricane at developmental stage 1 vs. SAP1 (primocane at developmental stage 1, SAF2 vs. SAP2, SAF3 vs. SAP3, SAP1 vs. SAP2, SAP1 vs. SAP3, and SAP2 vs. SAP3, respectively. SAP1 maintains an extension growth pattern; SAP2 then exhibits growth arrest and vertical (downward gravitropic deflection; and finally, short roots begin to form on the apex of SAP3. The Kyoto Encyclopedia of Genes and Genomes enrichment analysis of SAP1 vs. SAP2 revealed 12 pathways that were activated in response to shoot growth arrest and root differentiation, including circadian rhythm—plant (ko04712 and plant hormone signal transduction (ko04075. Our results indicate that genes related to circadian rhythm, ethylene and auxin signaling, shoot growth, and root development are potentially involved in the regulation of primocane apex rooting in Rubus. These findings provide a basis for elucidating the molecular mechanisms of primocane apex rooting in this economically valuable crop.

  13. Evaluation of Mycorrhizal Fungi, Vermicompost and Humic Acid on Essence Yield and Root Colonization of Fennel

    Directory of Open Access Journals (Sweden)

    I. Akbari

    2016-02-01

    Full Text Available Introduction The main objective of sustainable agriculture is to decrease the off-farm inputs such as chemical fertilizers, increased farm nutrient cycle through reduced tillage and the use of biological and organic fertilizers. Studies on medicinal plants indicates that the use of sustainable farming systems provide the best conditions for the production of these plants. Mycorrhizal fungi, vermicompost and humic acid are samples of biological and organic fertilizer that can be used, to eliminate or substantially reduce the use of chemical inputs in order to increase the quantity, quality and stability of the products. Mycorrhizal fungi are one of the most important rhizosphere microorganisms which have symbiotic relation with root of most crops. Mycorrhizal symbiosis improves the soil physical (through expansion of hyphae of fungus, chemical (through increased absorption of nutrients and biological (the soil food web quality. These fungus increased nutrient uptake, such as phosphorus and some micronutrients, water uptake, reducing the negative effects of environmental stress and increase resistance to pathogens and improve the quality of their host plants. Fennel (Foeniculum vulgare Mill is one of the most important medicinal plants, as the essential oil from the seeds used in a variety of industries, pharmaceutical, food and cosmetic use. Anethole is important component of the essential oil of fennel seed. Materials and Methods This experiment was conducted as a factorial based on randomized complete block design in order to evaluate the effects of vermicompost application, humic acid and mycorrhizal fungi on quantitative and qualitative aspects of fennel yield at experimental farm of Shahrood University during growing season of 1391-92. This experiment includes 12 treatments and 3 applications. Vermicompost levels include: v1 (no application v2 (4 ton ha-1 v3 (8 ton ha-1. Mycorrhizal fungi include: m1 (no inoculation and m2 (inoculation and

  14. Polyamine biosynthesis and degradation are modulated by exogenous gamma-aminobutyric acid in root-zone hypoxia-stressed melon roots.

    Science.gov (United States)

    Wang, Chunyan; Fan, Longquan; Gao, Hongbo; Wu, Xiaolei; Li, Jingrui; Lv, Guiyun; Gong, Binbin

    2014-09-01

    We detected physiological change and gene expression related to PA metabolism in melon roots under controlled and hypoxic conditions with or without 5 mM GABA. Roots with hypoxia treatment showed a significant increase in glutamate decarboxylase (GAD) activity and endogenous GABA concentration. Concurrently, PA biosynthesis and degradation accelerated with higher gene expression and enzymes activity. However, endogenous GABA concentrations showed a large and rapid increase in Hypoxia + GABA treated roots. This led to a marked increase in Glu concentration by feedback inhibition of GAD activity. Hypoxia + GABA treatment enhanced arginine (Arg), ornithine (Orn) and methionine (Met) levels, promoting enzyme gene expression levels and arginine decarboxylase (ADC), ornithine decarboxylase (ODC) and S-adenosylmethionine decarboxylase (SAMDC) activities in roots. Hypoxia + GABA treatment significantly increased concentrations of free putrescine (Put), spermidine (Spd) and spermine (Spm) from day two to eight, promoting the PA conversion to soluble conjugated and insoluble bound forms. However, PA degradation was significantly inhibited in hypoxia + GABA treated roots by significantly decreasing gene expression and activity of diamine oxidase (DAO) and polyamine oxidase (PAO). However, exogenous GABA showed a reduced effect in control compared with hypoxic conditions. Our data suggest that alleviating effect of exogenous GABA to hypoxia is closely associated with physiological regulation of PA metabolism. We propose a potential negative feedback mechanism of higher endogenous GABA levels from combined effects of hypoxia and exogenous GABA, which alleviate the hypoxia damage by accelerating PA biosynthesis and conversion as well as preventing PA degradation in melon plants.

  15. Site-specific function and regulation of Osterix in tooth root formation

    Science.gov (United States)

    He, Y. D.; Sui, B. D.; Li, M.; Huang, J.; Chen, S.; Wu, L. A.

    2016-01-01

    Congenital diseases of tooth roots, in terms of developmental abnormalities of short and thin root phenotypes, can lead to loss of teeth. A more complete understanding of the genetic molecular pathways and biological processes controlling tooth root formation is required. Recent studies have revealed that Osterix (Osx), a key mesenchymal transcriptional factor participating in both the processes of osteogenesis and odontogenesis, plays a vital role underlying the mechanisms of developmental differences between root and crown. During tooth development, Osx expression has been identified from late embryonic to postnatal stages when the tooth root develops, particularly in odontoblasts and cementoblasts to promote their differentiation and mineralization. Furthermore, the site-specific function of Osx in tooth root formation has been confirmed, because odontoblastic Osx-conditional knockout mice demonstrate primarily short and thin root phenotypes with no apparent abnormalities in the crown (Journal of Bone and Mineral Research 30, 2014 and 742, Journal of Dental Research 94, 2015 and 430). These findings suggest that Osx functions to promote odontoblast and cementoblast differentiation and root elongation only in root, but not in crown formation. Mechanistic research shows regulatory networks of Osx expression, which can be controlled through manipulating the epithelial BMP signalling, mesenchymal Runx2 expression and cellular phosphorylation levels, indicating feasible routes of promoting Osx expression postnatally (Journal of Cellular Biochemistry 114, 2013 and 975). In this regard, a promising approach might be available to regenerate the congenitally diseased root and that regenerative therapy would be the best choice for patients with developmental tooth diseases. PMID:26599722

  16. Developmental Characteristics and Cinnamic Acid Resistance of Root Border Cells in Cucumber and Figleaf Gourd Seedlings

    Institute of Scientific and Technical Information of China (English)

    QIAO Yong-xu; ZHANG Yong-ping; ZHANG Hong-xin; TIAN Yong-qiang; GAO Li-hong

    2013-01-01

    Root border cells (RBCs) originate from the root tip epidermis and surround the root apices. In this study, we evaluated the developmental characteristics and the roles of RBCs in protection of root apices of cucumber and ifgleaf gourd seedlings from CA toxicity. The formation of RBCs and the emergence of the root tip occurred almost simultaneously in root apices of cucumber and ifgleaf gourd seedlings. CA ranging from 0 to 0.25 mol L-1 inhibited root elongation and decreased root cell viability in the root tip, moreover the inhibitory effects of CA were more signiifcant in the CA-sensitive cucumber than in the CA-tolerant ifgleaf gourd. Removal of RBCs from root tips led to more severe CA induced inhibition of root elongation and decline in root cell viability. Increasing CA levels and treatment time decreased the relative viability of attached and detached RBCs. CA also induced a thicker mucilage layer surrounding attached RBCs of both species. Additionally, a signiifcantly higher relative cell viability of attached RBCs and thicker mucilage layers were observed in ifgleaf gourd. These results suggest that RBCs play an important role in protecting root tips from CA toxicity.

  17. Pinoid kinase regulates root gravitropism through modulation of PIN2-dependent basipetal auxin transport in Arabidopsis thaliana

    Science.gov (United States)

    Muday, Gloria; Sukumar, Poornima; Edwards, Karin; Delong, Alison; Rahman, Abidur

    Reversible protein phosphorylation is a key regulatory mechanism governing polar auxin transport. We tested the hypothesis that PINOID (PID)-mediated phosphorylation and RCN1- regulated dephosphorylation might antagonistically regulate auxin transport and gravity response in seedling roots. Here we show that basipetal IAA transport and gravitropism are reduced in pid mutant seedlings, while acropetal transport and lateral root development are unchanged. Treatment of wild-type seedlings with the protein kinase inhibitor, staurosporine, phenocopied the reduced auxin transport and gravity response of pid-9 and reduced formation of asymmetric DR5-revGFP expression at the root tip after reorientation relative to gravity. Gravitropism and auxin transport in pid are resistant to further inhibition by staurosporine. Gravity response defects of rcn1 and pid-9 are partially rescued by treatment with staurosporine or the phosphatase inhibitor, cantharidin, respectively, and in the pid-9 rcn1 double mutant. Furthermore, the effect of staurosporine is lost in pin2, and a PIN2::GFP fusion protein accumulates in endomembrane compartments after staurosporine treatment. In the pid-9 mutant, immunological techniques find a similar PIN2 localization. These data suggest that staurosporine inhibits gravitropism and basipetal IAA transport by blocking PID action and altering PIN2 localization and support the model that PID and RCN1 reciprocally regulate root gravitropic curvature.

  18. Regulation of hepatic gene expression by saturated fatty acids.

    Science.gov (United States)

    Vallim, T; Salter, A M

    2010-01-01

    Diets rich in saturated fatty acids have long been associated with increased plasma cholesterol concentrations and hence increased risk of cardiovascular disease. More recently, they have also been suggested to promote the development of non-alcoholic fatty liver disease. While there is now considerable evidence to suggest that polyunsaturated fatty acids exert many of their effects through regulating the activity of transcription factors, including peroxisome proliferator activated receptors, sterol regulatory binding proteins (SREBPs) and liver X receptor, our understanding of how saturated fatty acids act is still limited. Here we review the potential mechanisms whereby saturated fatty acids modulate hepatic lipid metabolism thereby impacting on the synthesis, storage and secretion of lipids. Evidence is presented that their effects are, at least partly, mediated through modulation of the activity of the SREBP family of transcription factors.

  19. AMPK-independent pathways regulate skeletal muscle fatty acid oxidation

    DEFF Research Database (Denmark)

    Dzamko, Nicolas; Schertzer, Jonathan D.; Ryall, James G.

    2008-01-01

    , malonyl-CoA levels were reduced and rates of fatty acid oxidation were comparable between genotypes. During treadmill exercise both KD and WT mice had similar values of respiratory exchange ratio. These studies suggested the presence of an alternative ACC2 kinase(s). Using a phosphoproteomics......The activation of AMP-activated protein kinase (AMPK) and phosphorylation/inhibition of acetyl-CoA carboxylase 2 (ACC2) is believed to be the principal pathway regulating fatty acid oxidation. However, during exercise AMPK activity and ACC Ser-221 phosphorylation does not always correlate...... with rates of fatty acid oxidation. To address this issue we have investigated the requirement for skeletal muscle AMPK in controlling aminoimidazole-4-carboxymide-1-beta-d-ribofuranoside (AICAR) and contraction-stimulated fatty acid oxidation utilizing transgenic mice expressing a muscle-specific kinase...

  20. Propofol up-regulates Mas receptor expression in dorsal root ganglion neurons.

    Science.gov (United States)

    Cao, Lijun; Xun, Junmei; Jiang, Xinghua; Tan, Rong

    2013-08-01

    Mas is a functional binding site for angiotensin (Ang)-(1-7), a critical component of the renin-angiotensin system that is involved in processing nociceptive information. A recent study reported the localization of Mas in rat dorsal root ganglia (DRG) and demonstrated that Ang-(1-7) produced a dose-dependent peripheral antinociceptive effect in rats through the Mas receptor by an opioid-independent mechanism. In the present study, we for the first time examined the effect of propofol on Mas expression in cultured DRG neurons. We treated rat DRG neurons with propofol at different concentrations (0.1, 0.5, 1, 5 or 10 microM) for different length of time (0.5, 1, 2, 4 or 6 h) with or without transcription inhibitor actinomycin D or different kinase inhibitors. Propofol increased the Mas receptormRNA level in a statistically significant dose- and time-dependent manner within 4 h, which led to dose-dependent up-regulation of the Mas receptor protein level as well as Ang-(1-7) binding on the cell membrane. Actinomycin D (1 mg/ml) and p38 mitogen-activated protein kinase inhibitor PD169316 (25 microM) completely abolished the effect of propofol on Mas receptor expression in DRG neurons. In conclusion, we demonstrate that propofol markedly up-regulates Mas receptor expression at the transcription level in DRG neurons by a p38 MAPK-dependent mechanism. This study provides new insights into the mechanisms of action of propofol in peripheral antinociception, and suggests a new regulatory mechanism on the Ang-(1-7)/Mas axis in the peripheral nervous system.

  1. PERK–KIPK–KCBP signalling negatively regulates root growth in Arabidopsis thaliana

    Science.gov (United States)

    Humphrey, Tania V.; Haasen, Katrina E.; Aldea-Brydges, May Grace; Sun, He; Zayed, Yara; Indriolo, Emily; Goring, Daphne R.

    2015-01-01

    The Arabidopsis proline-rich, extensin-like receptor-like kinases (PERKs) are a small group of receptor-like kinases that are thought to act as sensors at the cell wall through their predicted proline-rich extracellular domains. In this study, we focused on the characterization of a subclade of three Arabidopsis predicted PERK genes, PERK8, -9, and -10, for which no functions were known. Yeast two-hybrid interaction studies were conducted with the PERK8,- 9, and -10 cytosolic kinase domains, and two members of the Arabidopsis AGC VIII kinase family were identified as interacting proteins: AGC1-9 and the closely related kinesin-like calmodulin-binding protein (KCBP)-interacting protein kinase (KIPK). As KIPK has been identified previously as an interactor of KCBP, these interactions were also examined further and confirmed in this study. Finally, T-DNA mutants for each gene were screened for altered phenotypes under different conditions, and from these screens, a role for the PERK, KIPK, and KCBP genes in negatively regulating root growth was uncovered. PMID:25262228

  2. Regulation of iron acquisition responses in plant roots by a transcription factor.

    Science.gov (United States)

    Bauer, Petra

    2016-09-10

    The presented research hypothesis-driven laboratory exercise teaches advanced undergraduate students state of the art methods and thinking in an integrated molecular physiology context. Students understand the theoretical background of iron acquisition in the model plant Arabidopsis thaliana. They design a flowchart summarizing the key steps of the experimental approach. Students are made familiar with current techniques such as qPCR. Following their experimental outline, students grow Arabidopsis seedlings up to the age of six days under sufficient and deficient iron supply. The Arabidopsis plants are of two different genotypes, namely wild type and fit loss of function mutants. fit mutants lack the essential transcription factor FIT, required for iron acquisition and plant growth. Students monitor growth phenotypes and root iron reductase activity in a quantitative and qualitative manner. Then, students determine gene expression regulation of FIT, FRO2, and a reference gene by reverse transcription-quantitative PCR (RT-qPCR). Finally, students interpet their results and build a model summarizing the connections between morphological, physiological and molecular iron deficiency responses. Learning outcomes and suggestions for integrating the course concept are explained. © 2016 by The International Union of Biochemistry and Molecular Biology, 44(5):438-449, 2016.

  3. MES buffer affects Arabidopsis root apex zonation and root growth by suppressing superoxide generation in root apex

    Directory of Open Access Journals (Sweden)

    Tomoko eKagenishi

    2016-02-01

    Full Text Available In plants, growth of roots and root hairs is regulated by the fine cellular control of pH and reactive oxygen species. MES, 2-(N-morpholinoethanesulfonic acid as one of the Good’s buffers has broadly been used for buffering medium, and it is thought to suit for plant growth with the concentration at 0.1% (w/v because the buffer capacity of MES ranging pH 5.5-7.0 (for Arabidopsis, pH 5.8. However, many reports have shown that, in nature, roots require different pH values on the surface of specific root apex zones, namely meristem, transition zone and elongation zone. Despite the fact that roots always grow on a media containing buffer molecule, little is known about impact of MES on root growth. Here, we have checked the effects of different concentrations of MES buffer using growing roots of Arabidopsis thaliana. Our results show that 1% of MES significantly inhibited root growth, the number of root hairs and length of meristem, whereas 0.1% promoted root growth and root apex area (region spanning from the root tip up to the transition zone. Furthermore, superoxide generation in root apex disappeared at 1% of MES. These results suggest that MES disturbs normal root morphogenesis by changing the reactive oxygen species (ROS homeostasis in root apex.

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

    Science.gov (United States)

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

    2015-01-01

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

  5. Regulation of intestinal mucosal growth by amino acids.

    Science.gov (United States)

    Ray, Ramesh M; Johnson, Leonard R

    2014-03-01

    Amino acids, especially glutamine (GLN) have been known for many years to stimulate the growth of small intestinal mucosa. Polyamines are also required for optimal mucosal growth, and the inhibition of ornithine decarboxylase (ODC), the first rate-limiting enzyme in polyamine synthesis, blocks growth. Certain amino acids, primarily asparagine (ASN) and GLN stimulate ODC activity in a solution of physiological salts. More importantly, their presence is also required before growth factors and hormones such as epidermal growth factor and insulin are able to increase ODC activity. ODC activity is inhibited by antizyme-1 (AZ) whose synthesis is stimulated by polyamines, thus, providing a negative feedback regulation of the enzyme. In the absence of amino acids mammalian target of rapamycin complex 1 (mTORC1) is inhibited, whereas, mTORC2 is stimulated leading to the inhibition of global protein synthesis but increasing the synthesis of AZ via a cap-independent mechanism. These data, therefore, explain why ASN or GLN is essential for the activation of ODC. Interestingly, in a number of papers, AZ has been shown to inhibit cell proliferation, stimulate apoptosis, or increase autophagy. Each of these activities results in decreased cellular growth. AZ binds to and accelerates the degradation of ODC and other proteins shown to regulate proliferation and cell death, such as Aurora-A, Cyclin D1, and Smad1. The correlation between the stimulation of ODC activity and the absence of AZ as influenced by amino acids is high. Not only do amino acids such as ASN and GLN stimulate ODC while inhibiting AZ synthesis, but also amino acids such as lysine, valine, and ornithine, which inhibit ODC activity, increase the synthesis of AZ. The question remaining to be answered is whether AZ inhibits growth directly or whether it acts by decreasing the availability of polyamines to the dividing cells. In either case, evidence strongly suggests that the regulation of AZ synthesis is the

  6. Plant regulators for rooting of hardwood cuttings of blackberry plants cv. Xavante/ Reguladores vegetais no enraizamento de estacas lenhosas da amoreira-preta cv. Xavante

    Directory of Open Access Journals (Sweden)

    Renato Vasconcelos Botelho

    2008-08-01

    Full Text Available Aiming to evaluate the use of plant regulators for rooting of hardwood cuttings of blackberry cv. Xavante, two experiments were carried out in a greenhouse. In the first one the concentrations of indolil butyric acid varied in 0, 1000, 1500, 2000, 2500 and 3000 mg L-1. And in the second one, the plant regulator that was used was paclobutrazol at the concentrations of 0, 200, 400, 600, 800 and 1000 mg L-1. For each experiment the base of the cuttings were dipped in the solutions for ten seconds. After that, the cuttings were planted in rigid plastic vases with sand and kept under intermittent misty system. The following variables were evaluated, 71 days after planting: percentage of rooted cuttings, percentage of callus presence, average length of roots, number of roots, fresh weight of roots, percentage of sprouting. The treatment of hardwood cuttings with 2000 mg L-1 IBA had the greatest percentage of rooting (60%. Nevertheless, the treatment with 1000 mg L-1 IBA attained already high rooting percentage (56%, with 96% of sprouted cuttings and 17.6 roots per cutting. Cuttings treated with PBZ presented greater callus presence but they did not root, thus it is not possible to recommend this product for rooting of blackberry plants cv. Xavante among the tested concentrations.Com o objetivo de avaliar o emprego de reguladores vegetais no enraizamento de estacas lenhosas da amora-preta cv. Xavante dois experimentos foram conduzidos em casa-de-vegetação. No primeiro, empregou-se o ácido indol butírico (AIB nas concentrações de 0, 1000, 1500, 2000, 2500, 3000 mg L-1. No segundo, o regulador utilizado foi o paclobutrazol (PBZ nas concentrações de 0, 200, 400, 600, 800, 1000 mg L-1. Em ambos os experimentos as estacas ficaram imersas por 10 segundos nas respectivas soluções. Posteriormente foram plantados em vasos de plástico rígido contendo areia, sendo mantidas em casade- vegetação sob nebulização intermitente. Após 71 dias do plantio

  7. [Effects of 6-benzylaminopurine and α-naphthaleneacetic acid on growth and isoflavone contents of Pueraria phaseoloides hairy roots].

    Science.gov (United States)

    He, Hanjie; Shi, Heping

    2014-10-01

    In order to study the effect of phytohormone on growth and isoflavones contents of Pueraria phaseoloides hairy roots, we cultured the hairy roots with different concentrations of 6-benzylaminopurine (6-BA) alone or in combination with α-naphthaleneacetic acid (NAA). Then we determined the effects of 6-BA alone or in combination with NAA on the growth and the contents of isoflavones compounds and levels of antioxidase activities of hairy roots by spectrophotometry. The results show that 6-BA inhibited the growth, and decreased biomass and total isoflavones compounds of P. phaseoloides hairy roots. Furthermore, the inhibition was increased with the concentrations of 6-BA. Compared with the controls, different concentrations of 6-BA in combination with NAA 2.0 mg/L could inhibit the growth of hairy roots and decrease the content of total isoflavone compounds, and also significantly enhanced the contents of soluble protein and levels of peroxidase (POD) activities, but decreased the activities of superoxide dismutase (SOD). DNA ladders detected by agarose gel electrophoresis can be observed after hairy roots of P. phaseoloides were cultured with 6-BA alone for 30 days, but can appear on the 20th day after culture with 6-BA in combination with NAA 2.0 mg/L. This result indicates that 6-BA or 6-BA in combination with NAA can both stimulate appearance of programmed cell death (PCD), and NAA may play a synergistic role on PCD.

  8. Retinoic acid signalling in thymocytes regulates T cell development

    DEFF Research Database (Denmark)

    Wendland, Kerstin; Sitnik, Katarzyna Maria; Kotarsky, Knut

    precursor entry and/or survival. Furthermore, CD4Cre-dnRAR mice showed a 4-fold reduction in CD4+/CD8+ SP ratio that was mainly due to enhanced accumulation of mature CD8+ SP cells, indicating that RA signaling may be directly involved in regulating thymic retention and/or post-selection expansion......The Vitamin A derivative retinoic acid (RA) has emerged as an important regulator of peripheral T cell responses. However, whether there is endogenous retinoic acid receptor (RAR) signaling in developing thymocytes and the potential impact of such signals in thymocyte development remains unclear....... 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...

  9. An Investigation on Physiological and Photosynthetic Parameters of Forage Maize at Regulated Deficit Irrigation and Partial Root Zone Draying Methods

    Directory of Open Access Journals (Sweden)

    Nader Naderi

    2017-02-01

    Full Text Available Introduction: Water shortage is the most important factor affecting crop production in the world. The deficit irrigation is a way to reduce water consumption in farming. The Partial Root- zone Drying (PRD irrigation is a new improvement in deficit irrigation in which the half of the root zone is irrigated alternatively in scheduled irrigation events. In the fixed partial root zone drying (FPRD the irrigation is fixed to one side of the root zone in the growing season. Maize is a drought sensitive crop. In maize, secondary traits related to drought resistance are considered in producing tolerate cultivars. Materials and Methods: An experiment was conducted in order to investigate the effects of regulated deficit irrigation, variable partial root zone drying (PRD and fixed partial root zone drying (FPRD on the yield, physiological and photosynthetic parameters of forage maize (KSC 704 during the growing seasons of 2014 in Mashhad region. A factorial experiment based on randomized complete block design with four replications was carried out. The treatments included the full irrigation (FI and the deficit irrigations (regulated deficit irrigation (DI and the replacements of 80 % (DI80 and 60 % (DI60 of total water requirement, fixed PRD (FPRD at 100% (FPRD100, 80% (FPRD80 and 60%(FPRD60 of water requirement, and variable PRD at 100% (PRD100, 80% (PRD80 and 60% (PRD60 of water requirement. Drip irrigation tapes were placed between plant rows. In the full irrigation and regulated deficit irrigation treatments, the plants were irrigated from two sides for every irrigation. In the PRD, one of two neighboring tapes was alternatively used for irrigation. In FPRD, a drip tape was used for two plant rows and irrigation was fixed to one side of the root. The irrigation interval was 3 days for all treatments. Dry and fresh forage yield, leaf area index (LAI, stomatal conductance, leaf relative water content (RWC and chlorophyll content were measured. Results

  10. Regulation of length and density of Arabidopsis root hairs by ammonium and nitrate.

    Science.gov (United States)

    Vatter, Thomas; Neuhäuser, Benjamin; Stetter, Markus; Ludewig, Uwe

    2015-09-01

    Root hairs expand the effective root surface to increase the uptake of nutrients and water from the soil. Here the local effects of the two major nitrogen sources, ammonium and nitrate, on root hairs were investigated using split plates. In three contrasting accessions of A. thaliana, namely Col-0, Tsu-0 and Sha, root hairs were differentially affected by the nitrogen forms and their concentration. Root hairs in Sha were short in the absence of nitrate. In Col-0, hair length was moderately decreased with increasing nitrate or ammonium. In all accessions, the root hair density was insensitive to 1,000-fold changes in the ammonium concentrations, when supplied locally as the exclusive nitrogen form. In contrast, the root hair density generally increased with nitrate as the exclusive local nitrogen source. The nitrate sensitivity was reduced at mM concentrations in a loss-of-function mutant of the nitrate transporter and sensor gene NRT1;1 (NPF6.3). Little differences with respect to ammonium were found in a mutant lacking four high affinity AMT-type ammonium transporters, but interestingly, the response to high nitrate was reduced and may indicate a general defect in nitrogen signaling in that mutant. Genetic diversity and the presence of the nitrogen transceptor NRT1;1 explain heterogeneity in the responses of root hairs to different nitrogen forms in Arabidopsis accessions.

  11. Carbonic anhydrase 5 regulates acid-base homeostasis in zebrafish.

    Directory of Open Access Journals (Sweden)

    Ruben Postel

    Full Text Available The regulation of the acid-base balance in cells is essential for proper cellular homeostasis. Disturbed acid-base balance directly affects cellular physiology, which often results in various pathological conditions. In every living organism, the protein family of carbonic anhydrases regulate a broad variety of homeostatic processes. Here we describe the identification, mapping and cloning of a zebrafish carbonic anhydrase 5 (ca5 mutation, collapse of fins (cof, which causes initially a collapse of the medial fins followed by necrosis and rapid degeneration of the embryo. These phenotypical characteristics can be mimicked in wild-type embryos by acetazolamide treatment, suggesting that CA5 activity in zebrafish is essential for a proper development. In addition we show that CA5 regulates acid-base balance during embryonic development, since lowering the pH can compensate for the loss of CA5 activity. Identification of selective modulators of CA5 activity could have a major impact on the development of new therapeutics involved in the treatment of a variety of disorders.

  12. Amino acids regulate the intracellular trafficking of the general amino acid permease of Saccharomycescerevisiae.

    Science.gov (United States)

    Chen, Esther J; Kaiser, Chris A

    2002-11-12

    The delivery to the plasma membrane of the general amino acid permease, Gap1p, of Saccharomyces cerevisiae is regulated by the quality of the nitrogen source in the growth medium. In an effort to define how different nitrogen sources control Gap1p sorting, we find that mutations in GDH1 and GLN1 that decrease the flux through the glutamate and glutamine synthesis pathways result in increased Gap1p sorting to the plasma membrane. Conversely, deletion of MKS1, which increases glutamate and glutamine synthesis, decreases Gap1p sorting to the plasma membrane. Glutamate and glutamine are not unusual in their ability to regulate Gap1p sorting, because the addition of all natural amino acids and many amino acid analogs to the growth medium results in increased Gap1p sorting to the vacuole. Importantly, amino acids have the capacity to signal Gap1p sorting to the vacuole regardless of whether they can be used as a source of nitrogen. Finally, we show that rapamycin does not affect Gap1p sorting, indicating that Gap1p sorting is not directly influenced by the TOR pathway. Together, these data show that amino acids are a signal for sorting Gap1p to the vacuole and imply that the nitrogen-regulated Gap1p sorting machinery responds to amino acid-like compounds rather than to the overall nutritional status associated with growth on a particular nitrogen source.

  13. Rhizobium acidisoli sp. nov., isolated from root nodules of Phaseolus vulgaris in acid soils.

    Science.gov (United States)

    Román-Ponce, Brenda; Jing Zhang, Yu; Soledad Vásquez-Murrieta, María; Hua Sui, Xin; Feng Chen, Wen; Carlos Alberto Padilla, Juan; Wu Guo, Xian; Lian Gao, Jun; Yan, Jun; Hong Wei, Ge; Tao Wang, En

    2016-01-01

    Two Gram-negative, aerobic, non-motile, rod-shaped bacterial strains, FH13T and FH23, representing a novel group of Rhizobium isolated from root nodules of Phaseolus vulgaris in Mexico, were studied by a polyphasic analysis. Phylogeny of 16S rRNA gene sequences revealed them to be members of the genus Rhizobium related most closely to 'Rhizobium anhuiense' CCBAU 23252 (99.7 % similarity), Rhizobium leguminosarum USDA 2370T (98.6 %), and Rhizobium sophorae CCBAU 03386T and others ( ≤ 98.3 %). In sequence analyses of the housekeeping genes recA, glnII and atpD, both strains formed a subclade distinct from all defined species of the genus Rhizobium at sequence similarities of 82.3-94.0 %, demonstrating that they represented a novel genomic species in the genus Rhizobium. Mean levels of DNA-DNA relatedness between the reference strain FH13T and the type strains of related species varied between 13.0 ± 2.0 and 52.1 ± 1.2 %. The DNA G+C content of strain FH13T was 63.5 mol% (Tm). The major cellular fatty acids were 16 : 0, 17 : 0 anteiso, 18 : 0, summed feature 2 (12 : 0 aldehyde/unknown 10.928) and summed feature 8 (18 : 1ω7c). The fatty acid 17 : 1ω5c was unique for this strain. Some phenotypic features, such as failure to utilize adonitol, l-arabinose, d-fructose and d-fucose, and ability to utilize d-galacturonic acid and itaconic acid as carbon source, could also be used to distinguish strain FH13T from the type strains of related species. Based upon these results, a novel species, Rhizobium acidisoli sp. nov., is proposed, with FH13T ( = CCBAU 101094T = HAMBI 3626T = LMG 28672T) as the type strain.

  14. Regulation of inflammation by short chain fatty acids.

    Science.gov (United States)

    Vinolo, Marco A R; Rodrigues, Hosana G; Nachbar, Renato T; Curi, Rui

    2011-10-01

    The short chain fatty acids (SCFAs) acetate (C(2)), propionate (C(3)) and butyrate (C(4)) are the main metabolic products of anaerobic bacteria fermentation in the intestine. In addition to their important role as fuel for intestinal epithelial cells, SCFAs modulate different processes in the gastrointestinal (GI) tract such as electrolyte and water absorption. These fatty acids have been recognized as potential mediators involved in the effects of gut microbiota on intestinal immune function. SCFAs act on leukocytes and endothelial cells through at least two mechanisms: activation of GPCRs (GPR41 and GPR43) and inhibiton of histone deacetylase (HDAC). SCFAs regulate several leukocyte functions including production of cytokines (TNF-α, IL-2, IL-6 and IL-10), eicosanoids and chemokines (e.g., MCP-1 and CINC-2). The ability of leukocytes to migrate to the foci of inflammation and to destroy microbial pathogens also seems to be affected by the SCFAs. In this review, the latest research that describes how SCFAs regulate the inflammatory process is presented. The effects of these fatty acids on isolated cells (leukocytes, endothelial and intestinal epithelial cells) and, particularly, on the recruitment and activation of leukocytes are discussed. Therapeutic application of these fatty acids for the treatment of inflammatory pathologies is also highlighted.

  15. Regulation of Inflammation by Short Chain Fatty Acids

    Directory of Open Access Journals (Sweden)

    Renato T. Nachbar

    2011-10-01

    Full Text Available The short chain fatty acids (SCFAs acetate (C2, propionate (C3 and butyrate (C4 are the main metabolic products of anaerobic bacteria fermentation in the intestine. In addition to their important role as fuel for intestinal epithelial cells, SCFAs modulate different processes in the gastrointestinal (GI tract such as electrolyte and water absorption. These fatty acids have been recognized as potential mediators involved in the effects of gut microbiota on intestinal immune function. SCFAs act on leukocytes and endothelial cells through at least two mechanisms: activation of GPCRs (GPR41 and GPR43 and inhibiton of histone deacetylase (HDAC. SCFAs regulate several leukocyte functions including production of cytokines (TNF-α, IL-2, IL-6 and IL-10, eicosanoids and chemokines (e.g., MCP-1 and CINC-2. The ability of leukocytes to migrate to the foci of inflammation and to destroy microbial pathogens also seems to be affected by the SCFAs. In this review, the latest research that describes how SCFAs regulate the inflammatory process is presented. The effects of these fatty acids on isolated cells (leukocytes, endothelial and intestinal epithelial cells and, particularly, on the recruitment and activation of leukocytes are discussed. Therapeutic application of these fatty acids for the treatment of inflammatory pathologies is also highlighted.

  16. Comparison of acidic and neutral PH root conditioners prior to a coronally positioned flap to treat gingival recession

    Directory of Open Access Journals (Sweden)

    Roya Shariatmadar Ahmadi

    2014-01-01

    Full Text Available Background: Localized gingival recession can be treated successfully via coronally positioned flap (CPF and additional use of root surface demineralization agents. The purpose of this study was to evaluate the effects of additional use of ethylene diamine tetraacetic acid (EDTA and citric acid as a root conditioner in association with CPF to cover localized buccal gingival recessions. Materials and Methods: Twenty-seven patients with 66 Miller class I buccal gingival recession ≥ 2 mm on single-rooted teeth were studied. Patients were randomly assigned: CPF with EDTA gel (test 1 and CPF with saturated citric acid (test 2 or CPF alone (control. Clinical parameters were measured at baseline and 1, 2, 3 and 6 months after surgery; assessment included recession depth (RD, clinical attachment level (CAL, probing depth (PD and height of keratinized gingiva (HKG. SPSS version-20 was used to perform all statistical analyses. Data was reported as Mean ± SD. Age, RD, CAL, PD, and HKG before treatment and after 6 months among study groups were compared by one-way ANOVA followed by the Tukey test. The level of significance was considered to be less than 0.05. Results: At 6 months, all treatment modalities showed significant root coverage and gain in CAL. RD was reduced from 2.86 ± 0.76 mm to 0.55±0.53 mm in the EDTA group and from 2.37±0.57 mm to 1.03±0.43 mm in the acid group and from 2.37±0.54 mm to 0.85±0.49 mm in the control group. The average percentage of root coverage for the EDTA, acid, and control groups were 80.73%, 52.16%, and 64.50%, respectively. At 6 months, there was a significant difference (P < 0.05 in all parameters for the EDTA group (except HKG that did not vary among the groups. Conclusion: Root preparation with EDTA was an effective procedure to cover localized gingival recessions and significantly improved the amount of root coverage obtained.

  17. Counter-regulatory phosphatases TNAP and NPP1 temporally regulate tooth root cementogenesis

    Institute of Scientific and Technical Information of China (English)

    Laura E Zweifler; Mudita K Patel; Francisco H Nociti Jr; Helen F Wimer; Jose L Milla n; Martha J Somerman; Brian L Foster

    2015-01-01

    Cementum is critical for anchoring the insertion of periodontal ligament fibers to the tooth root. Several aspects of cementogenesis remain unclear, including differences between acellular cementum and cellular cementum, and between cementum and bone. Biomineralization is regulated by the ratio of inorganic phosphate (Pi) to mineral inhibitor pyrophosphate (PPi), where local Pi and PPi concentrations are controlled by phosphatases including tissue-nonspecific alkaline phosphatase (TNAP) and ectonucleotide pyrophosphatase/phosphodiesterase 1 (NPP1). The focus of this study was to define the roles of these phosphatases in cementogenesis. TNAP was associated with earliest cementoblasts near forming acellular and cellular cementum. With loss of TNAP in the Alpl null mouse, acellular cementum was inhibited, while cellular cementum production increased, albeit as hypomineralized cementoid. In contrast, NPP1 was detected in cementoblasts after acellular cementum formation, and at low levels around cellular cementum. Loss of NPP1 in the Enpp1 null mouse increased acellular cementum, with little effect on cellular cementum. Developmental patterns were recapitulated in a mouse model for acellular cementum regeneration, with early TNAP expression and later NPP1 expression. In vitro, cementoblasts expressed Alpl gene/protein early, whereas Enpp1 gene/protein expression was significantly induced only under mineralization conditions. These patterns were confirmed in human teeth, including widespread TNAP, and NPP1 restricted to cementoblasts lining acellular cementum. These studies suggest that early TNAP expression creates a low PPi environment promoting acellular cementum initiation, while later NPP1 expression increases PPi, restricting acellular cementum apposition. Alterations in PPi have little effect on cellular cementum formation, though matrix mineralization is affected.

  18. AINTEGUMENTA and the D-type cyclin CYCD3;1 regulate root secondary growth and respond to cytokinins.

    Science.gov (United States)

    Randall, Ricardo S; Miyashima, Shunsuke; Blomster, Tiina; Zhang, Jing; Elo, Annakaisa; Karlberg, Anna; Immanen, Juha; Nieminen, Kaisa; Lee, Ji-Young; Kakimoto, Tatsuo; Blajecka, Karolina; Melnyk, Charles W; Alcasabas, Annette; Forzani, Celine; Matsumoto-Kitano, Miho; Mähönen, Ari Pekka; Bhalerao, Rishikesh; Dewitte, Walter; Helariutta, Ykä; Murray, James A H

    2015-09-04

    Higher plant vasculature is characterized by two distinct developmental phases. Initially, a well-defined radial primary pattern is established. In eudicots, this is followed by secondary growth, which involves development of the cambium and is required for efficient water and nutrient transport and wood formation. Regulation of secondary growth involves several phytohormones, and cytokinins have been implicated as key players, particularly in the activation of cell proliferation, but the molecular mechanisms mediating this hormonal control remain unknown. Here we show that the genes encoding the transcription factor AINTEGUMENTA (ANT) and the D-type cyclin CYCD3;1 are expressed in the vascular cambium of Arabidopsis roots, respond to cytokinins and are both required for proper root secondary thickening. Cytokinin regulation of ANT and CYCD3 also occurs during secondary thickening of poplar stems, suggesting this represents a conserved regulatory mechanism. © 2015. Published by The Company of Biologists Ltd.

  19. AINTEGUMENTA and the D-type cyclin CYCD3;1 regulate root secondary growth and respond to cytokinins

    Directory of Open Access Journals (Sweden)

    Ricardo S. Randall

    2015-10-01

    Full Text Available Higher plant vasculature is characterized by two distinct developmental phases. Initially, a well-defined radial primary pattern is established. In eudicots, this is followed by secondary growth, which involves development of the cambium and is required for efficient water and nutrient transport and wood formation. Regulation of secondary growth involves several phytohormones, and cytokinins have been implicated as key players, particularly in the activation of cell proliferation, but the molecular mechanisms mediating this hormonal control remain unknown. Here we show that the genes encoding the transcription factor AINTEGUMENTA (ANT and the D-type cyclin CYCD3;1 are expressed in the vascular cambium of Arabidopsis roots, respond to cytokinins and are both required for proper root secondary thickening. Cytokinin regulation of ANT and CYCD3 also occurs during secondary thickening of poplar stems, suggesting this represents a conserved regulatory mechanism.

  20. AINTEGUMENTA and the D-type cyclin CYCD3;1 regulate root secondary growth and respond to cytokinins

    Science.gov (United States)

    Randall, Ricardo S.; Miyashima, Shunsuke; Blomster, Tiina; Zhang, Jing; Elo, Annakaisa; Karlberg, Anna; Immanen, Juha; Nieminen, Kaisa; Lee, Ji-Young; Kakimoto, Tatsuo; Blajecka, Karolina; Melnyk, Charles W.; Alcasabas, Annette; Forzani, Celine; Matsumoto-Kitano, Miho; Mähönen, Ari Pekka; Bhalerao, Rishikesh; Dewitte, Walter; Helariutta, Ykä; Murray, James A. H.

    2015-01-01

    ABSTRACT Higher plant vasculature is characterized by two distinct developmental phases. Initially, a well-defined radial primary pattern is established. In eudicots, this is followed by secondary growth, which involves development of the cambium and is required for efficient water and nutrient transport and wood formation. Regulation of secondary growth involves several phytohormones, and cytokinins have been implicated as key players, particularly in the activation of cell proliferation, but the molecular mechanisms mediating this hormonal control remain unknown. Here we show that the genes encoding the transcription factor AINTEGUMENTA (ANT) and the D-type cyclin CYCD3;1 are expressed in the vascular cambium of Arabidopsis roots, respond to cytokinins and are both required for proper root secondary thickening. Cytokinin regulation of ANT and CYCD3 also occurs during secondary thickening of poplar stems, suggesting this represents a conserved regulatory mechanism. PMID:26340943

  1. Combined acid rain and lanthanum pollution and its potential ecological risk for nitrogen assimilation in soybean seedling roots.

    Science.gov (United States)

    Zhang, Fan; Cheng, Mengzhu; Sun, Zhaoguo; Wang, Lihong; Zhou, Qing; Huang, Xiaohua

    2017-08-22

    Rare earth elements (REEs) are used in various fields, resulting in their accumulation in the environment. This accumulation has affected the survival and distribution of crops in various ways. Acid rain is a serious global environmental problem. The combined effects on crops from these two types of pollution have been reported, but the effects on crop root nitrogen assimilation are rarely known. To explore the impact of combined contamination from these two pollutants on crop nitrogen assimilation, the soybean seedlings were treated with simulated environmental pollution from acid rain and a representative rare earth ion, lanthanum ion (La(3+)), then the indexes related to plant nitrogen assimilation process in roots were determined. The results showed that combined treatment with pH 4.5 acid rain and 0.08 mM La(3+) promoted nitrogen assimilation synergistically, while the other combined treatments all showed inhibitory effects. Moreover, acid rain aggravated the inhibitory effect of 1.20 or 0.40 mM La(3+) on nitrogen assimilation in soybean seedling roots. Thus, the effects of acid rain and La(3+) on crops depended on the combination levels of acid rain intensity and La(3+) concentration. Acid rain increases the bioavailability of La(3+), and the combined effects of these two pollutants were more serious than that of either pollutant alone. These results provide new evidence in favor of limiting overuse of REEs in agriculture. This work also provides a new framework for ecological risk assessment of combined acid rain and REEs pollution on soybean crops. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Organic acid compounds in root exudation of Moso Bamboo (Phyllostachys pubescens) and its bioactivity as affected by heavy metals.

    Science.gov (United States)

    Chen, Junren; Shafi, Mohammad; Wang, Ying; Wu, Jiasen; Ye, Zhengqian; Liu, Chen; Zhong, Bin; Guo, Hua; He, Lizhi; Liu, Dan

    2016-10-01

    Moso bamboo (Phyllostachys pubescens) has great potential as phytoremediation material in soil contaminated by heavy metals. A hydroponics experiment was conducted to determine organic acid compounds of root exudates of lead- (Pb), zinc- (Zn), copper- (Cu), and cadmium (Cd)-tolerant of Moso bamboo. Plants were grown in nutrients solution which included Pb, Zn, Cu, and Cd applied as Pb(NO3)2 (200 μM), ZnSO4·7H2O (100 μM), CuSO4·5H2O (25 μM), and CdCl2 (10 μM), respectively. Oxalic acid and malic acid were detected in all treatments. Lactic acid was observed in Cu, Cd, and control treatments. The oxalic was the main organic acid exudated by Moso bamboo. In the sand culture experiment, the Moso bamboo significantly activated carbonate heavy metals under activation of roots. The concentration of water-soluble metals (except Pb) in sand were significantly increased as compared with control. Organic acids (1 mM mixed) were used due to its effect on the soil adsorption of heavy metals. After adding mixed organic acids, the Cu and Zn sorption capacity in soils was decreased markedly compared with enhanced Pb and Cd sorption capacity in soils. The sorption was analyzed using Langmuir and Freundlich equations with R (2) values that ranged from 0.956 to 0.999 and 0.919 to 0.997, respectively.

  3. Regulation of retinoid receptors by retinoic acid and axonal contact in Schwann cells.

    Directory of Open Access Journals (Sweden)

    Maria-Jesus Latasa

    Full Text Available BACKGROUND: Schwann cells (SCs are the cell type responsible for the formation of the myelin sheath in the peripheral nervous system (PNS. As retinoic acid (RA and other retinoids have a profound effect as regulators of the myelination program, we sought to investigate how their nuclear receptors levels were regulated in this cell type. METHODOLOGY/PRINCIPAL FINDINGS: In the present study, by using Schwann cells primary cultures from neonatal Wistar rat pups, as well as myelinating cocultures of Schwann cells with embryonic rat dorsal root ganglion sensory neurons, we have found that sustained expression of RXR-γ depends on the continuous presence of a labile activator, while axonal contact mimickers produced an increase in RXR-γ mRNA and protein levels, increment that could be prevented by RA. The upregulation by axonal contact mimickers and the transcriptional downregulation by RA were dependent on de novo protein synthesis and did not involve changes in mRNA stability. On the other hand, RAR-β mRNA levels were only slightly modulated by axonal contact mimickers, while RA produced a strong transcriptional upregulation that was independent of de novo protein synthesis without changes in mRNA stability. CONCLUSIONS/SIGNIFICANCE: All together, our results show that retinoid receptors are regulated in a complex manner in Schwann cells, suggesting that they could have a prominent role as regulators of Schwann cell physiology.

  4. Root-secreted nicotianamine from Arabidopsis halleri facilitates zinc hypertolerance by regulating zinc bioavailability.

    Science.gov (United States)

    Tsednee, Munkhtsetseg; Yang, Shun-Chung; Lee, Der-Chuen; Yeh, Kuo-Chen

    2014-10-01

    Hyperaccumulators tolerate and accumulate extraordinarily high concentrations of heavy metals. Content of the metal chelator nicotianamine (NA) in the root of zinc hyperaccumulator Arabidopsis halleri is elevated compared with nonhyperaccumulators, a trait that is considered to be one of the markers of a hyperaccumulator. Using metabolite-profiling analysis of root secretions, we found that excess zinc treatment induced secretion of NA in A. halleri roots compared with the nonhyperaccumulator Arabidopsis thaliana. Metal speciation analysis further revealed that the secreted NA forms a stable complex with Zn(II). Supplying NA to a nonhyperaccumulator species markedly increased plant zinc tolerance by decreasing zinc uptake. Therefore, NA secretion from A. halleri roots facilitates zinc hypertolerance through forming a Zn(II)-NA complex outside the roots to achieve a coordinated zinc uptake rate into roots. Secretion of NA was also found to be responsible for the maintenance of iron homeostasis under excess zinc. Together our results reveal root-secretion mechanisms associated with hypertolerance and hyperaccumulation. © 2014 American Society of Plant Biologists. All Rights Reserved.

  5. 4,4,4-trifluoro-3-(indole-3-)butyric acid promotes root elongation in Lactuca sativa independent of ethylene synthesis and pH

    Science.gov (United States)

    Zhang, Nenggang; Hasenstein, Karl H.

    2002-01-01

    We studied the mode of action of 4,4,4-trifluoro-3- (indole-3-) butyric acid (TFIBA), a recently described root growth stimulator, on primary root growth of Lactuca sativa L. seedlings. TFIBA (100 micromoles) promoted elongation of primary roots by 40% in 72 h but inhibited hypocotyl growth by 35%. TFIBA induced root growth was independent of pH. TFIBA did not affect ethylene production, but reduced the inhibitory effect of ethylene on root elongation. TFIBA promoted root growth even in the presence of the ethylene biosynthesis inhibitor L-alpha-(2-aminoethoxyvinyl)glycine. TFIBA and the ethylene-binding inhibitor silver thiosulphate (STS) had a similar effect on root elongation. The results indicate that TFIBA-stimulated root elongation was neither pH-dependent nor related to inhibition of ethylene synthesis, but was possibly related to ethylene action.

  6. 4,4,4-trifluoro-3-(indole-3-)butyric acid promotes root elongation in Lactuca sativa independent of ethylene synthesis and pH

    Science.gov (United States)

    Zhang, Nenggang; Hasenstein, Karl H.

    2002-01-01

    We studied the mode of action of 4,4,4-trifluoro-3- (indole-3-) butyric acid (TFIBA), a recently described root growth stimulator, on primary root growth of Lactuca sativa L. seedlings. TFIBA (100 micromoles) promoted elongation of primary roots by 40% in 72 h but inhibited hypocotyl growth by 35%. TFIBA induced root growth was independent of pH. TFIBA did not affect ethylene production, but reduced the inhibitory effect of ethylene on root elongation. TFIBA promoted root growth even in the presence of the ethylene biosynthesis inhibitor L-alpha-(2-aminoethoxyvinyl)glycine. TFIBA and the ethylene-binding inhibitor silver thiosulphate (STS) had a similar effect on root elongation. The results indicate that TFIBA-stimulated root elongation was neither pH-dependent nor related to inhibition of ethylene synthesis, but was possibly related to ethylene action.

  7. The interplay between rainfall infiltration depth, rooting depth and water table depth in regulating Amazon evapotranspiration (ET)

    Science.gov (United States)

    Miguez-Macho, Gonzalo; Fan, Ying; Dominguez, Francina

    2017-04-01

    Plants link the subsurface to the atmosphere via water and carbon fluxes and are therefore a key player in climate. The Amazon, one of Earth's largest ecosystems, is an important climate regulator. As a large source of evapotranspiration, it has significant influence on regional and remote precipitation dynamics. For its equatorial position, it impacts significantly the global climate engine. The Amazon receives abundant annual rainfall but parts of it experience a multi-month dry season. Here we elucidate the interplay among three hydrological depths: precipitation infiltration depth, root water uptake-depth, and the water table depth in regulating dry-season ET, using inverse modeling based on observed productivity, ERA Interim reanalysis atmosphere, and a novel integrated soil-surface-groundwater model with dynamic root uptake to meet the transpiration demand. We perform high-resolution ( 1km) multi-year simulations over the region, with shallow soil, deep soil, with and without groundwater, with and without dynamic rooting depth; attempting to tease out these components. The results demonstrate the strong interactions among the three depths and what each factor does in regulating dry season ET, shedding light on how future global change may preferentially impact Amazon ecosystem functioning.

  8. Evaluation of smear layer removal and marginal adaptation of root canal sealer after final irrigation using ethylenediaminetetraacetic, peracetic, and etidronic acids with different concentrations.

    Science.gov (United States)

    Ulusoy, Özgür İlke; Zeyrek, Salev; Çelik, Bülent

    2017-02-12

    The purpose of this study was to investigate the effects of different irrigation solutions on the smear layer removal and marginal adaptation of a resin-based sealer to root canal dentine. A total of 152 instrumented roots were irrigated with the following irrigants: 9,18% etidronic acid (HEBP), 0.5, 1,2% peracetic acid (PAA), 17% ethylenediaminetetraacetic acid (EDTA), saline. The amount of smear layer was evaluated using scanning electron microscope (SEM) in seventy root samples. Eighty-two roots were filled with AH Plus and gutta-percha. Slices obtained from apical third of each specimen were viewed with SEM to assess marginal adaptation. Use of 9% and 18% HEBP resulted in more efficient smear layer removal in the apical third than the other chelators (p acid is a promising candidate for final irrigation of root canals.

  9. Effect of 1-naphthaleneacetic acid on organic acid exudation by the roots of white lupin plants grown under phosphorus-deficient conditions.

    Science.gov (United States)

    Gómez, Diego A; Carpena, Ramón O

    2014-09-15

    The effect of NAA (1-naphthaleneacetic acid) on organic acid exudation in white lupin plants grown under phosphorus deficiency was investigated. Plants were sampled periodically for collecting of organic acids (citrate, malate, succinate), and also were used to study the effect on proton extrusion and release of Na(+), K(+), Ca(2+) and Mg(2+). The tissues were later processed to quantify the organic acids in tissues, the phosphorus content and the effects on plant biomass. The exogenous addition of NAA led to an increase in organic acid exudation, but this response was not proportional to the concentration of the dose applied, noticing the largest increments with NAA 10(-8)M. In contrast the increase in root weight was proportional to the dose applied, which shows that with higher doses the roots produced are not of proteoid type. Proton extrusion and the release of cations were related to the NAA dose, the first was proportional to the dose applied and the second inversely proportional. Regarding the analysis of tissues, the results of citrate and phosphorus content in shoots show that the overall status of these parts are the main responsible of the organic acids exuded. NAA served as an enhancer of the organic acid exudation that occurs under phosphorus deficient conditions, with a response that depends on the dose applied, not only in its magnitude, but also in the mechanism of action of the plant hormone.

  10. A transcription factor with a bHLH domain regulates root hair development in rice

    Institute of Scientific and Technical Information of China (English)

    Wona Ding; Zhiming Yu; Yanli Tong; Wei Huang; Hanmin Chen; Ping Wu

    2009-01-01

    @@ Dear Editor, In plants,root hairs are important organs for the uptake of nutrients and water from the rhizosphere and serve as sites of interaction with soil microorganisms [1].A root hair grows as an extension of a single epidermal cell and is a simple system,making it an elegant model for studying higher plant cell differentiation and cell fate determination.Three types of root hair pattern have been suggested [2,3].Arabidopsis has the striped pattern(Type 3)of root hairs,which has been extensively reported [4,5].Type 2 patterns depend on asymmetrical cell division,which is found in rice(Oryza sativa L.),Barley(Hordeum vulgare)and wheat(Triticum aestivum).

  11. The roles of mechanical compression and chemical irritation in regulating spinal neuronal signaling in painful cervical nerve root injury.

    Science.gov (United States)

    Zhang, Sijia; Nicholson, Kristen J; Smith, Jenell R; Gilliland, Taylor M; Syré, Peter P; Winkelstein, Beth A

    2013-11-01

    Both traumatic and slow-onset disc herniation can directly compress and/or chemically irritate cervical nerve roots, and both types of root injury elicit pain in animal models of radiculopathy. This study investigated the relative contributions of mechanical compression and chemical irritation of the nerve root to spinal regulation of neuronal activity using several outcomes. Modifications of two proteins known to regulate neurotransmission in the spinal cord, the neuropeptide calcitonin gene-related peptide (CGRP) and glutamate transporter 1 (GLT-1), were assessed in a rat model after painful cervical nerve root injuries using a mechanical compression, chemical irritation or their combination of injury. Only injuries with compression induced sustained behavioral hypersensitivity (p≤0.05) for two weeks and significant decreases (p<0.037) in CGRP and GLT-1 immunoreactivity to nearly half that of sham levels in the superficial dorsal horn. Because modification of spinal CGRP and GLT-1 is associated with enhanced excitatory signaling in the spinal cord, a second study evaluated the electrophysiological properties of neurons in the superficial and deeper dorsal horn at day 7 after a painful root compression. The evoked firing rate was significantly increased (p=0.045) after compression and only in the deeper lamina. The painful compression also induced a significant (p=0.002) shift in the percentage of neurons in the superficial lamina classified as low- threshold mechanoreceptive (sham 38%; compression 10%) to those classified as wide dynamic range neurons (sham 43%; compression 74%). Together, these studies highlight mechanical compression as a key modulator of spinal neuronal signaling in the context of radicular injury and pain.

  12. Cyclic phosphatidic acid and lysophosphatidic acid induce hyaluronic acid synthesis via CREB transcription factor regulation in human skin fibroblasts.

    Science.gov (United States)

    Maeda-Sano, Katsura; Gotoh, Mari; Morohoshi, Toshiro; Someya, Takao; Murofushi, Hiromu; Murakami-Murofushi, Kimiko

    2014-09-01

    Cyclic phosphatidic acid (cPA) is a naturally occurring phospholipid mediator and an analog of the growth factor-like phospholipid lysophosphatidic acid (LPA). cPA has a unique cyclic phosphate ring at the sn-2 and sn-3 positions of its glycerol backbone. We showed before that a metabolically stabilized cPA derivative, 2-carba-cPA, relieved osteoarthritis pathogenesis in vivo and induced hyaluronic acid synthesis in human osteoarthritis synoviocytes in vitro. This study focused on hyaluronic acid synthesis in human fibroblasts, which retain moisture and maintain health in the dermis. We investigated the effects of cPA and LPA on hyaluronic acid synthesis in human fibroblasts (NB1RGB cells). Using particle exclusion and enzyme-linked immunosorbent assays, we found that both cPA and LPA dose-dependently induced hyaluronic acid synthesis. We revealed that the expression of hyaluronan synthase 2 messenger RNA and protein is up-regulated by cPA and LPA treatment time dependently. We then characterized the signaling pathways up-regulating hyaluronic acid synthesis mediated by cPA and LPA in NB1RGB cells. Pharmacological inhibition and reporter gene assays revealed that the activation of the LPA receptor LPAR1, Gi/o protein, phosphatidylinositol-3 kinase (PI3K), extracellular-signal-regulated kinase (ERK), and cyclic adenosine monophosphate response element-binding protein (CREB) but not nuclear factor κB induced hyaluronic acid synthesis by the treatment with cPA and LPA in NB1RGB cells. These results demonstrate for the first time that cPA and LPA induce hyaluronic acid synthesis in human skin fibroblasts mainly through the activation of LPAR1-Gi/o followed by the PI3K, ERK, and CREB signaling pathway.

  13. In vitro growth inhibition of intra root canal pathogenic microorganisms by Lactic Acid Bacteria, an Antibiosis method

    Directory of Open Access Journals (Sweden)

    A. Nakhjavani F.

    2008-12-01

    Full Text Available "nBackground and Aim: Elimination of microorganisms and their byproducts from root canal system is one of important aims of root canal therapy. This object is gained by using of many chemomechanical techniques but with noncertain success. A new method is used of nonpathogenic bacteria for growth inhibition of pathogenic bacteria, Antibiosis, in root canal therapy.The aim of this study was in vitro evaluation of antimicrobial effect of probiotics, such as Lactic Acid Bacteria (LAB on the infected root canal bacteria. "nMaterials and Methods: Isolated bacteria from infected root canal were grown and then scattered onto the muller Hinton agar plates which contain wells, LAB, extracted from dairy products, were added into these wells, Inhibition effected of LAB was determined. Furthermore the sample taken from the inhibition zone and possible resistant monoclonal bacteria also were identified, then 6 sensitive and 14 resistant samples were selected and E. faecalis species were added to them; Then antimicrobial effects of LAB on these samples was reevaluated. "nResults: The results showed that 66.7% of the samples were sensitive at least to one type of LAB, and 33% were resistant to all kind of LAB. Meanwhile the outgrowing anaerobic bacteria inside the inhibition zone were from the low frequency oral bacterial flora. Furthermore, adding E. faecalis to the samples caused more sensitivity of them to LAB. Mc-Neamar test recognized the difference significant. "nConclusion: This study showed that the LAB inhibit growth of the pathogenic root canal bacteriae. Furthermore, presence of E. faecalis reinforces the antimicrobial effect of LAB. It seemed that LAB maybe have potential to use in endodontic practice for elimination of root canal infections.

  14. A Novel Rice Gene, NRR Responds to Macronutrient Deficiency and Regulates Root Growth

    Institute of Scientific and Technical Information of China (English)

    Yu-Man Zhang; Xiao-Ying Chen; Yong-Sheng Yan; Li-Na Wang; Kun Yang; Na Xiao; Yun-Feng Liu; Ya-Ping Fu; Zong-Xiu Sun; Rong-Xiang Fang

    2012-01-01

    To better understand the response of rice to nutrient stress,we have taken a systematic approach to identify rice genes that respond to deficiency of macronutrients and affect rice growth.We report here the expression and biological functions of a previously uncharacterized rice gene that we have named NRR (nutrition response and root growth).NRR is alternatively spliced,producing two 5′-coterminal transcripts,NRRa and NRRb,encoding two proteins of 308 and 223 aa,respectively.Compared to NRRb,NRRa possesses an additional CCT domain at the C-terminus.Expression of NRR in rice seedling roots was significantly influenced by deficiency of macronutrients.Knock-down of expression of NRRa or NRRb by RNA interference resulted in enhanced rice root growth.By contrast,overexpression of NRRa in rice exhibited significantly retarded root growth.These results revealed that both NRRa and NRRb played negative regulatory roles in rice root growth.Our findings suggest that NRRa and NRRb,acting as the key components,modulate the rice root architecture with the availability of macronutrients.

  15. Seasonal variations in the concentrations of lipophilic compounds and phenolic acids in the roots of Echinacea purpurea and Echinacea pallida.

    Science.gov (United States)

    Thomsen, Maria O; Fretté, Xavier C; Christensen, Kathrine B; Christensen, Lars P; Grevsen, Kai

    2012-12-12

    Roots of Echinacea purpurea and Echinacea pallida cultivated for 4 years in a North European climate were analyzed for seasonal variations in the concentrations of lipophilic constituents (alkamides, ketoalkenes, and ketoalkynes) and phenolic acids by harvesting five times during 1 year to establish the optimal time for harvest. A total of 16 alkamides, three ketoalkenes, two ketoalkynes, and four phenolic acids (echinacoside, cichoric acid, caftaric acid, and chlorogenic acid) were identified in aqueous ethanolic (70%) extracts by liquid chromatography-mass spectrometry and quantified by reverse-phase high-performance liquid chromatography. The major alkamides in the roots of E. purpurea were at their lowest concentration in the middle of autumn and early winter, and the total concentration of lipophilic compounds in E. pallida showed the same pattern. Moreover, all of the major phenolic acids in E. purpurea were at their highest concentrations in spring. The optimal harvest time in spring is in contrast to normal growing guidelines; hence, this specific information of seasonal variations in the concentrations of lipophilic and phenolic compounds in E. purpurea and E. pallida is valuable for research, farmers, and producers of medicinal preparations.

  16. De novo Sequencing and Transcriptome Analysis Reveal Key Genes Regulating Steroid Metabolism in Leaves, Roots, Adventitious Roots and Calli of Periploca sepium Bunge

    Directory of Open Access Journals (Sweden)

    Xinglin Li

    2017-04-01

    Full Text Available Periploca sepium Bunge is a traditional medicinal plant, whose root bark is important for Chinese herbal medicine. Its major bioactive compounds are C21 steroids and periplocin, a kind of cardiac glycoside, which are derived from the steroid synthesis pathway. However, research on P. sepium genome or transcriptomes and their related genes has been lacking for a long time. In this study we estimated this species nuclear genome size at 170 Mb (using flow cytometry. Then, RNA sequencing of four different tissue samples of P. sepium (leaves, roots, adventitious roots, and calli was done using the sequencing platform Illumina/Solexa Hiseq 2,500. After de novo assembly and quantitative assessment, 90,375 all-transcripts and 71,629 all-unigenes were finally generated. Annotation efforts that used a number of public databases resulted in detailed annotation information for the transcripts. In addition, differentially expressed genes (DEGs were identified by using digital gene profiling based on the reads per kilobase of transcript per million reads mapped (RPKM values. Compared with the leaf samples (L, up-regulated genes and down-regulated genes were eventually obtained. To deepen our understanding of these DEGs, we performed two enrichment analyses: gene ontology (GO and Kyoto Encyclopedia of Genes and Genomes (KEGG. Here, the analysis focused upon the expression characteristics of those genes involved in the terpene metabolic pathway and the steroid biosynthesis pathway, to better elucidate the molecular mechanism of bioactive steroid synthesis in P. sepium. The bioinformatics analysis enabled us to find many genes that are involved in bioactive steroid biosynthesis. These genes encoded acetyl-CoA acetyltransferase (ACAT, HMG-CoA synthase (HMGS, HMG-CoA reductase (HMGR, mevalonate kinase (MK, phosphomevalonate kinase (PMK, mevalonate diphosphate decarboxylase (MDD, isopentenylpyrophosphate isomerase (IPPI, farnesyl pyrophosphate synthase (FPS

  17. Structural and Biochemical Changes in Salicylic-Acid-Treated Date Palm Roots Challenged with Fusarium oxysporum f. sp. albedinis

    Directory of Open Access Journals (Sweden)

    Abdelhi Dihazi

    2011-01-01

    Full Text Available Histochemical and ultrastructural analyses were carried out to assess structural and biochemical changes in date palm roots pretreated with salicylic acid (SA then inoculated with Fusarium oxysporum f. sp. albedinis (Foa. Flavonoids, induced proteins, and peroxidase activity were revealed in root tissues of SA-treated plants after challenge by Foa. These reactions were closely associated with plant resistance to Foa. Host reactions induced after inoculation of SA-treated plants with Foa included the plugging of intercellular spaces, the deposition of electron-dense materials at the sites of pathogen penetration, and several damages to fungal cells. On the other hand, untreated inoculated plants showed marked cell wall degradation and total cytoplasm disorganization, indicating the protective effects provided by salicylic acid in treated plants.

  18. The effect of mineral fertilization on the content of phenolic acids and mass of roots of Salvia miltiorrhiza Bunge

    Directory of Open Access Journals (Sweden)

    Waldemar Buchwald

    2013-12-01

    Full Text Available Research on the mineral fertilization of Salvia miltiorrhiza Bunge was carried out in the years 2000 - 2002. It was stated that the potassium fertilization has the strongest effect on the content of phenolic acids and on mass of roots of Salvia miltiorrhiza. The effect of atmospheric conditions in particular years is also essential. The optimal doses of fertilizers (pure component content in kg · ha- were the following: N - 100, P2O5 - 30, K20 - 180. Having used this fertilizing combination the average content of phenolic acids was 4,62% and the average aerial dry mass of roots was 13,21 g per 1 plant after one year of cultivation.

  19. [Effect of synthetic cyclopentane beta,beta'-triketones on amino acid metabolism in roots of buckwheat (Fagopyrum esculentum Moench.) seedlings].

    Science.gov (United States)

    Demina, E A; Tishchenko, L Ia; Shestak, O P; Novikov, V L; Anisimov, M M

    2009-01-01

    Germination of buckwheat seeds in solutions of synthetic mono- and tricyclic cyclopentane-containing beta,beta'-triketones of various concentrations was accompanied by inhibition of seedling root growth and changes in the contents of glutamate, gamma-aminobutyric acid, proline, glutamine, and alanine. The monocyclic triketone also affected the amount of isoleucine. It is likely that the increase in proline content is a nonspecific response significant for enhancing stress tolerance in seedlings.

  20. Transcriptional regulation of muscle fatty acid-binding protein.

    Science.gov (United States)

    Carey, J O; Neufer, P D; Farrar, R P; Veerkamp, J H; Dohm, G L

    1994-03-15

    Heart fatty acid-binding protein (H-FABP) is present in a wide variety of tissues but is found in the highest concentration in cardiac and red skeletal muscle. It has been proposed that the expression of H-FABP correlates directly with the fatty acid-oxidative capacity of the tissue. In the present study, the expression of H-FABP was measured in red and white skeletal muscle under two conditions in which fatty acid utilization is known to be increased: streptozotocin-induced diabetes and fasting. Protein concentration, mRNA concentration and transcription rate were measured under both conditions. The level of both protein and mRNA increased approximately 2-fold under each condition. The transcription rate was higher in red skeletal muscle than in white muscle, was increased 2-fold during fasting, but was unchanged by streptozotocin-induced diabetes. In addition to supporting the hypothesis that H-FABP is induced during conditions of increased fatty acid utilization, these findings demonstrate that the regulation of H-FABP expression may or may not be at the level of transcription depending on the stimulus.

  1. Post-Harvest Induced Production of Salvianolic Acids and Significant Promotion of Antioxidant Properties in Roots of Salvia miltiorrhiza (Danshen

    Directory of Open Access Journals (Sweden)

    Guo-Jun Zhou

    2014-05-01

    Full Text Available Danshen, the dried roots of Salvia miltiorrhiza, is an extremely valued Traditional Chinese Medicine. Previously, we have demonstrated that salvianolic acid B (SaB, the important bioactive ingredient in this herb, was a post-harvest product. Here, we further reported that all salvianolic acids (SAs in the roots were post-harvest products of the drying process. In addition, the results of various radical scavenging activity assays, including lipid peroxidation (1, DPPH (2, hydroxyl (3 and superoxide (4, were significantly increased along with the accumulation of total salvianolic acids in the process. The contents of chemical targets and antioxidant activities both reached the highest value under thermal treatment at 130 °C for 80 min. In this dehydration period, contents of SaB, and sum of nine SAs increased from 0.01% to 5.51%, and 0.20% to 6.61%; and IC50 of antioxidant activity decreased from 4.85 to 2.69 (1; 7.75 to 0.43 (2; 2.57 to 1.13 (3 and 17.25 to 1.10 mg/mL. These results further supported the hypothesis that the newly harvested plant roots were still physiologically active and the secondary metabolites might be produced due to dehydration stress after harvest. Our findings supplied an important and useful theoretical basis for promoting the quality of Danshen and other medicinal plant materials.

  2. Arabidopsis YAK1 regulates abscisic acid response and drought resistance

    KAUST Repository

    Kim, Dongjin

    2016-06-06

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

  3. Root defense analysis against Fusarium oxysporum reveals new regulators to confer resistance

    Science.gov (United States)

    Chen, Yi Chung; Wong, Chin Lin; Muzzi, Frederico; Vlaardingerbroek, Ido; Kidd, Brendan N.; Schenk, Peer M.

    2014-01-01

    Fusarium oxysporum is a root-infecting fungal pathogen that causes wilt disease on a broad range of plant species, including Arabidopsis thaliana. Investigation of the defense response against this pathogen had primarily been conducted using leaf tissue and little was known about the root defense response. In this study, we profiled the expression of root genes after infection with F. oxysporum by microarray analysis. In contrast to the leaf response, root tissue did not show a strong induction of defense-associated gene expression and instead showed a greater proportion of repressed genes. Screening insertion mutants from differentially expressed genes in the microarray uncovered a role for the transcription factor ETHYLENE RESPONSE FACTOR72 (ERF72) in susceptibility to F. oxysporum. Due to the role of ERF72 in suppressing programmed cell death and detoxifying reactive oxygen species (ROS), we examined the pub22/pub23/pub24 U-box type E3 ubiquitin ligase triple mutant which is known to possess enhanced ROS production in response to pathogen challenge. We found that the pub22/23/24 mutant is more resistant to F. oxysporum infection, suggesting that a heightened innate immune response provides protection against F. oxysporum. We conclude that root-mediated defenses against soil-borne pathogens can be provided at multiple levels. PMID:24998294

  4. MASSUGU2 encodes Aux/IAA19, an auxin-regulated protein that functions together with the transcriptional activator NPH4/ARF7 to regulate differential growth responses of hypocotyl and formation of lateral roots in Arabidopsis thaliana.

    Science.gov (United States)

    Tatematsu, Kiyoshi; Kumagai, Satoshi; Muto, Hideki; Sato, Atsuko; Watahiki, Masaaki K; Harper, Reneé M; Liscum, Emmanuel; Yamamoto, Kotaro T

    2004-02-01

    We have isolated a dominant, auxin-insensitive mutant of Arabidopsis thaliana, massugu2 (msg2), that displays neither hypocotyl gravitropism nor phototropism, fails to maintain an apical hook as an etiolated seedling, and is defective in lateral root formation. Yet other aspects of growth and development of msg2 plants are almost normal. These characteristics of msg2 are similar to those of another auxin-insensitive mutant, non-phototropic hypocotyl4 (nph4), which is a loss-of-function mutant of AUXIN RESPONSE FACTOR7 (ARF7) (Harper et al., 2000). Map-based cloning of the MSG2 locus reveals that all four mutant alleles result in amino acid substitutions in the conserved domain II of an Auxin/Indole-3-Acetic Acid protein, IAA19. Interestingly, auxin inducibility of MSG2/IAA19 gene expression is reduced by 65% in nph4/arf7. Moreover, MSG2/IAA19 protein binds to the C-terminal domain of NPH4/ARF7 in a Saccharomyces cerevisiae (yeast) two-hybrid assay and to the whole latter protein in vitro by pull-down assay. These results suggest that MSG2/IAA19 and NPH4/ARF7 may constitute a negative feedback loop to regulate differential growth responses of hypocotyls and lateral root formation.

  5. Simultaneous Inhibition of Linolenic Acid Synthesis in Winter Wheat Roots and Frost Hardening by BASF 13-338, a Derivative of Pyridazinone.

    Science.gov (United States)

    Willemot, C

    1977-07-01

    Treatment of 12-day-old winter wheat (Triticum aestivum) plants with BASF 13-338 {4-chloro-5 (dimethylamino)-2-phenyl-3(2H)-pyridazinone} 36 hours before frost hardening simultaneously and completely inhibits accumulation of linolenic acid in the roots during the hardening period and the acquisition of frost resistance. Increased unsaturation of fatty acids is therefore probably an important part of the mechanism of cold adaptation in winter wheat.BASF 13-338 also prevents the increase in per cent dry weight in roots and shoots during hardening and causes a decrease in root lipid phosphorus and total fatty acids.The concurrent increase in linoleic acid and decrease in linolenic acid in the treated plants, while the level of the other fatty acids is but little affected, suggest that BASF 13-338 specifically inhibits linoleic acid desaturase.

  6. Influence of concentration, time and method of application of citric acid and sodium citrate in root conditioning

    Directory of Open Access Journals (Sweden)

    Rodrigo Cavassim

    2012-06-01

    Full Text Available OBJECTIVES: The aim of this study was to establish the parameters of concentration, time and mode of application of citric acid and sodium citrate in relation to root conditioning. MATERIAL AND METHODS: A total of 495 samples were obtained and equally distributed among 11 groups (5 for testing different concentrations of citric acid, 5 for testing different concentrations of sodium citrate and 1 control group. After laboratorial processing, the samples were analyzed under scanning electron microscopy. A previously calibrated and blind examiner evaluated micrographs of the samples. Non-parametric statistical analysis was performed to analyze the data obtained. RESULTS: Brushing 25% citric acid for 3 min, promoted greater exposure of collagen fibers in comparison with the brushing of 1% citric acid for 1 minute and its topical application at 1% for 3 min. Sodium citrate exposed collagen fibers in a few number of samples. CONCLUSION: Despite the lack of statistical significance, better results for collagen exposure were obtained with brushing application of 25% citric acid for 3 min than with other application parameter. Sodium citrate produced a few number of samples with collagen exposure, so it is not indicated for root conditioning.

  7. Ovicidal activity of lactic acid produced by Lysobacter capsici YS1215 on eggs of root-knot nematode, Meloidogyne incognita.

    Science.gov (United States)

    Lee, Yong Seong; Naning, Kyaw Wai; Nguyen, Xuan Hoa; Kim, Sun Bae; Moon, Jae Hak; Kim, Kil Yong

    2014-11-28

    Lysobacter capsici YS1215 isolated from soil previously showed nematicidal potential for biological control of the root-knot nematode. In this study, lactic acid, a nematicidal compound, was isolated from culture filtrate of YS1215, and its ovicidal activity was investigated. Purification and identification of lactic acid were performed by a series of column chromatographies and identified by (1)H and (13)C NMR spectra and GC-MS analysis. Our results showed that bacterial culture filtrate containing lactic acid significantly inhibited egg hatching. The lowest egg hatch rate (5.9%) was found at a high concentration (25 μl/ml) of lactic acid at 5 days after incubation, followed by 20 (15.2%), 15 (23.7%), 10 (29.8%), and 5 (36.4%) μl/ml, while egg hatching in the control (sterile distilled water) was 44.5%. This is the first report of lactic acid as an ovicidal compound, and it may be considered as an alternative of chemical pesticide against root-knot nematodes.

  8. Functional analysis of cis-acting sequences regulating root-specific expression in transgenic tobacco

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Two different length fragments, RSF1 and RSF2 which contained the cis-acting sequences of root-spe- cific gene TobRB7, were isolated from tobacco genome. The abilities of these fragments to direct root-specific expression were studied by fusing them to the β-glucuronidase (GUS) report gene with different directions. After the recombined vectors were transformed into tobacco, the expression pattern was performed by histochemical staining and the quantitative analysis of GUS activity. The data suggested that the cis-acting element of TobRB7 gene direct GUS expression not only as root-specific but also as bidirectional. In our studies, the short fragment, RSF2, performed stronger activity than RSF1 with any direction. The stronger activity of GUS expression was determined by reverse inserting of RSF1 or RSF2 than positive inserting.

  9. A Beta vulgaris serine proteinase inhibitor gene (BvSTI) regulated by sugar beet root maggot feeding on moderately resistant F1016 roots.

    Science.gov (United States)

    Damage from the sugar beet root maggot (SBRM) is a serious problem and control of this devastating pest ultimately relies on environmentally damaging insecticides. To explore novel strategies for management of SBRM and gain knowledge of root defense response mechanisms, we examined root gene expres...

  10. Demineralization of root canal dentine with EDTA and citric acid in different concentrations, pH and application times

    Directory of Open Access Journals (Sweden)

    Mr.Sc. Nexhmije Ajeti

    2011-12-01

    Full Text Available Abstract The aims of the study are: 1. Determination of the amount of extracted Ca ions from den-tine using 17% and 10% EDTA, at pH 7 and pH 9. 2. Determination of the amount of extracted Ca ions from  den-tine using citric acid 5% and 1%, at pH 7 and pH 9.  Methodology 30 extracted, single rooted, human teeth were tested. Their crowns were sectioned at CEJ using diamond disks. The root canals were manually prepared with K-files #50-60. After each instrument 2.5 ml of 5.25% NaOCl was used and 0.9 NaCl as final irrigation. All teeth were longitudinally sectioned and 8 samples of dentine taken from each sample. EDTA 10% and 17 % and citric acid 1% and 5% in neutral and alkaline pH were used.  Each sample was immersed in acid and then exposure time was evaluated after 1, 5, 10, 15 and 25 min. The release rate of calcium ions from root dentine was evaluated by atomic absorption spectrometer.  Results There were significant differences in the amount of extracted Ca by citric acid 1% and 5% or EDTA 10% and 17% in human teeth.  Conclusions It may be concluded that EDTA is a better chelating agent than citric acid. The decalcifying activity of these solutions is related to the duration of exposure, pH and their concentrations.

  11. Phosphate Starvation Responses and Gibberellic Acid Biosynthesis Are Regulated by the MYB62 Transcription Factor in Arabiclopsis

    Institute of Scientific and Technical Information of China (English)

    Ballachanda N. Devaiah; Ramaiah Madhuvanthi; Athikkattuvalasu S. Karthikeyan; Kashchandra G. Raghothama

    2009-01-01

    The limited availability of phosphate (Pi) in most soils results in the manifestation of Pi starvation responses in plants. To dissect the transcriptional regulation of Pi stress-response mechanisms, we have characterized the biological role of MYB62, an R2R3-type MYB transcription factor that is induced in response to Pi deficiency. The induction of MYB62 is a specific response in the leaves during Pi deprivation. The MYB62 protein localizes to the nucleus. The overexpression of MYB62 resulted in altered root architecture, Pi uptake, and acid phosphatase activity, leading to decreased total Pi content in the shoots. The expression of several Pi starvation-induced (PSI) genes was also suppressed in the MYB62 overexpressing plants. Overexpression of MYB62 resulted in a characteristic gibberellic acid (GA)-deficient phenotype that could be partially reversed by exogenous application of GA. In addition, the expression of SOC1 and SUPERMAN, molecular regulators of flowering, was suppressed in the MYB62 overexpressing plants. Interestingly, the expression of these genes was also reduced during Pi deprivation in wild-type plants, suggesting a role for GA biosynthetic and floral regulatory genes in Pi starvation responses. Thus, this study highlights the role of MYB62 in the regulation of phosphate starvation responses via changes in GA metabolism and signaling. Such cross-talk between Pi homeostasis and GA might have broader implications on flowering, root development and adaptive mechanisms during nutrient stress.

  12. Effect of Plant Growth Regulators on Rooting of Cape Jasmine%植物生长调节剂对栀子扦插生根的影响

    Institute of Scientific and Technical Information of China (English)

    章志红; 蒋联方

    2012-01-01

    研究了4种植物生长调节剂对栀子(Gardenia jasminoides Ellis)一年生枝条扦插生根的影响.结果表明,栀子为中间生根型,属较易生根植物,以200 mg/L IBA处理1.5 h,其扦插生根率、平均生根数、平均根长和根系效果指数在各处理中表现最优.%The effect of four kinds of plant growth regulators on the rooting of one-year Cape jasmine was studied. The results showed that Cape jasmine was an easy rooting plant. The cttings rooting rate, average root number, average root length and root effects index reached the best when the branches were treated in 200 mg/L IBA solution for 1.5 h.

  13. Silencing the Transcriptional Repressor, ZCT1, Illustrates the Tight Regulation of Terpenoid Indole Alkaloid Biosynthesis in Catharanthus roseus Hairy Roots.

    Science.gov (United States)

    Rizvi, Noreen F; Weaver, Jessica D; Cram, Erin J; Lee-Parsons, Carolyn W T

    2016-01-01

    The Catharanthus roseus plant is the source of many valuable terpenoid indole alkaloids (TIAs), including the anticancer compounds vinblastine and vincristine. Transcription factors (TFs) are promising metabolic engineering targets due to their ability to regulate multiple biosynthetic pathway genes. To increase TIA biosynthesis, we elicited the TIA transcriptional activators (ORCAs and other unidentified TFs) with the plant hormone, methyl jasmonate (MJ), while simultaneously silencing the expression of the transcriptional repressor ZCT1. To silence ZCT1, we developed transgenic hairy root cultures of C. roseus that expressed an estrogen-inducible Zct1 hairpin for activating RNA interference. The presence of 17β-estradiol (5μM) effectively depleted Zct1 in hairy root cultures elicited with MJ dosages that either optimize or inhibit TIA production (250 or 1000μM). However, silencing Zct1 was not sufficient to increase TIA production or the expression of the TIA biosynthetic genes (G10h, Tdc, and Str), illustrating the tight regulation of TIA biosynthesis. The repression of the TIA biosynthetic genes at the inhibitory MJ dosage does not appear to be solely regulated by ZCT1. For instance, while Zct1 and Zct2 levels decreased through activating the Zct1 hairpin, Zct3 levels remained elevated. Since ZCT repressors have redundant yet distinct functions, silencing all three ZCTs may be necessary to relieve their repression of alkaloid biosynthesis.

  14. Human Prostatic Acid Phosphatase: Structure, Function and Regulation

    Directory of Open Access Journals (Sweden)

    William G. Chaney

    2013-05-01

    Full Text Available Human prostatic acid phosphatase (PAcP is a 100 kDa glycoprotein composed of two subunits. Recent advances demonstrate that cellular PAcP (cPAcP functions as a protein tyrosine phosphatase by dephosphorylating ErbB-2/Neu/HER-2 at the phosphotyrosine residues in prostate cancer (PCa cells, which results in reduced tumorigenicity. Further, the interaction of cPAcP and ErbB-2 regulates androgen sensitivity of PCa cells. Knockdown of cPAcP expression allows androgen-sensitive PCa cells to develop the castration-resistant phenotype, where cells proliferate under an androgen-reduced condition. Thus, cPAcP has a significant influence on PCa cell growth. Interestingly, promoter analysis suggests that PAcP expression can be regulated by NF-κB, via a novel binding sequence in an androgen-independent manner. Further understanding of PAcP function and regulation of expression will have a significant impact on understanding PCa progression and therapy.

  15. Peptide nucleic acid (PNA) binding-mediated gene regulation

    Institute of Scientific and Technical Information of China (English)

    2004-01-01

    Peptide nucleic acids (PNAs) are synthetic oligonucleotides with chemically modified backbones. PNAs can bind to both DNA and RNA targets in a sequence-specific manner to form PNA/DNA and PNA/RNA duplex structures. When bound to double-stranded DNA (dsDNA) targets, the PNA molecule replaces one DNA strand in the duplex by strand invasion to form a PNA/DNA/PNA [or (PNA)2/DNA] triplex structure and the displaced DNA strand exists as a singlestranded D-loop. PNA has been used in many studies as research tools for gene regulation and gene targeting. The Dloops generated from the PNA binding have also been demonstrated for its potential in initiating transcription and inducing gene expression. PNA provides a powerful tool to study the mechanism of transcription and an innovative strategy to regulate target gene expression. An understanding of the PNA-mediated gene regulation will have important clinical implications in treatment of many human diseases including genetic, cancerous, and age-related diseases.

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

    Science.gov (United States)

    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.

  17. Role of salicylic acid in alleviating oxidative damage in rice roots (Oryza sativa) subjected to cadmium stress

    Energy Technology Data Exchange (ETDEWEB)

    Guo, B. [Department of Plant Nutrition, College of Natural Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095 (China); Institute of Soil and Fertilizer, Zhejiang Academy of Agricultural Sciences, Hangzhou, 310021 (China); Liang, Y.C. [Institute of Soil and Fertilizer, Ministry of Agriculture Key Laboratory of Plant Nutrition and Nutrient Cycling, Chinese Academy of Agricultural Sciences, South Zhongguancun Street No. 12, Beijing 100081 (China)]. E-mail: ycliang@caas.ac.cn; Zhu, Y.G. [Research Center for Eco-environmental Sciences, Chinese Academy of Sciences, Beijing 100085 (China)]. E-mail: ygzhu@mail.rcees.ac.cn; Zhao, F.J. [Agriculture and Environment Division, Rothamsted Research, Harpenden, Herts AL5 2JQ (United Kingdom)

    2007-06-15

    Time-dependent changes in enzymatic and non-enzymatic antioxidants, and lipid peroxidation were investigated in roots of rice (Oryza sativa) grown hydroponically with Cd, with or without pretreatment of salicylic acid (SA). Exposure to 50 {mu}M Cd significantly decreased root growth, and activities of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD), but increased the concentrations of H{sub 2}O{sub 2}, malondialdehyde (MDA), ascorbic acid (AsA), glutathione (GSH) and non-protein thiols (NPT). However, pretreatment with 10 {mu}M SA enhanced the activities of antioxidant enzymes and the concentrations of non-enzymatic antioxidants, but lowered the concentrations of H{sub 2}O{sub 2} and MDA in the Cd-stressed rice compared with the Cd treatment alone. Pretreatment with SA alleviated the Cd-induced inhibition of root growth. The results showed that pretreatment with SA enhanced the antioxidant defense activities in Cd-stressed rice, thus alleviating Cd-induced oxidative damage and enhancing Cd tolerance. The possible mechanism of SA-induced H{sub 2}O{sub 2} signaling in mediating Cd tolerance was discussed. - Pretreatment with SA enhanced the antioxidant defense activities in Cd-stressed rice, thus alleviating Cd-induced oxidative damage and enhancing Cd tolerance.

  18. Novel roles of hydrogen peroxide (H₂O₂) in regulating pectin synthesis and demethylesterification in the cell wall of rice (Oryza sativa) root tips.

    Science.gov (United States)

    Xiong, Jie; Yang, Yongjie; Fu, Guanfu; Tao, Longxing

    2015-04-01

    Hydrogen peroxide (H₂O₂) has been reported to increase lignin formation, enhance cell wall rigidification, restrict cell expansion and inhibit root elongation. However, our results showed that it not only inhibited rice (Oryza sativa) root elongation, but also increased root diameter. No study has reported how and why H₂O₂ increases cell expansion and root diameter. Exogenous H₂O₂ and its scavenger 4-hydroxy-Tempo were applied to confirm the roles of H₂O₂. Immunofluorescence, fluorescence probe, ruthenium red staining, histological section and spectrophotometry were used to monitor changes in the degree of pectin methylesterification, pectin content, pectin methylesterase (PME) activity and H₂O₂ content. Exogenous H₂O₂ inhibited root elongation, but increased cell expansion and root diameter significantly. H₂O₂ not only increased the region of pectin synthesis and pectin content in root tips, but also increased PME activity and pectin demethylesterification. The scavenger 4-hydroxy-Tempo reduced root H₂O₂ content and recovered H₂O₂-induced increases in cell expansion and root diameter by inhibiting pectin synthesis, PME activity and pectin demethylesterification. H₂O₂ plays a novel role in the regulation of pectin synthesis, PME activity and pectin demethylesterification. H₂O₂ increases cell expansion and root diameter by increasing pectin content and demethylesterification.

  19. Antimicrobial Effects of a Lipophilic Fraction and Kaurenoic Acid Isolated from the Root Bark Extracts of Annona senegalensis

    Directory of Open Access Journals (Sweden)

    Theophine Chinwuba Okoye

    2012-01-01

    Full Text Available Root bark preparation of Annona senegalensis Pers. (Annonaceae is used in Nigerian ethnomedicine for treatment of infectious diseases. Extraction of the A. senegalensis powdered root bark with methanol-methylene chloride (1 : 1 mixture yielded the methanol-methylene extract (MME which was fractionated to obtain the ethyl acetate fraction (EF. The EF on further fractionation gave two active subfractions, F1 and F2. The F1 yielded a lipophilic oily liquid while F2 on purification, precipitated white crystalline compound, AS2. F1 was analyzed using GC-MS, while AS2 was characterized by proton NMR and X-ray crystallography. Antibacterial and antifungal studies were performed using agar-well-diffusion method with 0.5 McFarland standard and MICs calculated. GC-MS gave 6 major constituents: kaur-16-en-19-oic acid; 1-dodecanol; 1-naphthalenemethanol; 6,6-dimethyl-bicyclo[3.1.1]hept-2-ene-2-ethanol; 3,3-dimethyl-2-(3-methylbuta-1,3-dienylcyclohexane-1-methanol; 3-hydroxyandrostan-17-carboxylic acid. AS2 was found to be kaur-16-en-19-oic acid. The MICs of EF, F1, and AS2 against B. subtilis were 180, 60, and 30 μg/mL, respectively. AS2 exhibited activity against S. aureus with an MIC of 150 μg/mL, while F1 was active against P. aeruginosa with an MIC of 40 μg/mL. However, the extracts and AS2 exhibited no effects against Candida albicans and Aspergillus niger. Therefore, kaurenoic acid and the lipophilic fraction from A. senegalensis root bark exhibited potent antibacterial activity.

  20. Antimicrobial Effects of a Lipophilic Fraction and Kaurenoic Acid Isolated from the Root Bark Extracts of Annona senegalensis.

    Science.gov (United States)

    Okoye, Theophine Chinwuba; Akah, Peter Achunike; Okoli, Charles Ogbonnaya; Ezike, Adaobi Chioma; Omeje, Edwin Ogechukwu; Odoh, Uchenna Estella

    2012-01-01

    Root bark preparation of Annona senegalensis Pers. (Annonaceae) is used in Nigerian ethnomedicine for treatment of infectious diseases. Extraction of the A. senegalensis powdered root bark with methanol-methylene chloride (1 : 1) mixture yielded the methanol-methylene extract (MME) which was fractionated to obtain the ethyl acetate fraction (EF). The EF on further fractionation gave two active subfractions, F1 and F2. The F1 yielded a lipophilic oily liquid while F2 on purification, precipitated white crystalline compound, AS2. F1 was analyzed using GC-MS, while AS2 was characterized by proton NMR and X-ray crystallography. Antibacterial and antifungal studies were performed using agar-well-diffusion method with 0.5 McFarland standard and MICs calculated. GC-MS gave 6 major constituents: kaur-16-en-19-oic acid; 1-dodecanol; 1-naphthalenemethanol; 6,6-dimethyl-bicyclo[3.1.1]hept-2-ene-2-ethanol; 3,3-dimethyl-2-(3-methylbuta-1,3-dienyl)cyclohexane-1-methanol; 3-hydroxyandrostan-17-carboxylic acid. AS2 was found to be kaur-16-en-19-oic acid. The MICs of EF, F1, and AS2 against B. subtilis were 180, 60, and 30 μg/mL, respectively. AS2 exhibited activity against S. aureus with an MIC of 150 μg/mL, while F1 was active against P. aeruginosa with an MIC of 40 μg/mL. However, the extracts and AS2 exhibited no effects against Candida albicans and Aspergillus niger. Therefore, kaurenoic acid and the lipophilic fraction from A. senegalensis root bark exhibited potent antibacterial activity.

  1. Antiurolithiatic Activity of Extract and Oleanolic Acid Isolated from the Roots of Lantana camara on Zinc Disc Implantation Induced Urolithiasis.

    Science.gov (United States)

    Vyas, Narendra; Argal, Ameeta

    2013-01-01

    The present study was done to evaluate the antiurolithiatic activity of ethanolic extract of roots (ELC 200 mg/kg) and oleanolic acid (OA 60 mg/kg, O.A. 80 mg/kg, O.A. 100 mg/kg) isolated from roots of Lantana camara in albino wistar male rats using zinc disc implantation induced urolithiatic model. The group in which only zinc disc was implanted without any treatment showed increase in calcium output (23  ± 2.7 mg/dL). Cystone receiving animals showed significant protection from such change (P urolitiasis. Thus, OA and ELC showed promising antiurolithiatic activity in dose dependant manner.

  2. Isolation, purification and identification of ellagic acid derivatives, catechins, and procyanidins from the root bark of Anisophyllea dichostyla R. Br.

    Science.gov (United States)

    Khallouki, F; Haubner, R; Hull, W E; Erben, G; Spiegelhalder, B; Bartsch, H; Owen, R W

    2007-03-01

    The root bark of Anisophyllea dichostyla R. Br. is traditionally used in the Democratic Republic Congo for the treatment of several conditions such as anorexia, fatigue and intestinal infections. We have identified and quantitated several polyphenol antioxidants in the methanol extract of the root bark (120g). The polyphenol content (3.32g/kg) was predominantly ellagitannins (25%) and polyhydroxyflavan-3-ols (catechins and procyanidins, 75%) with 3'-O-methyl-3,4-methylenedioxo ellagic acid 4'-O-beta-d-glucopyranoside and (-)-epicatechin as the major species in each class. These two compounds and the following species were identified unequivocally by NMR spectroscopy: (+)-catechin, (-)-epicatechin 3-O-gallate, 3-O-methyl ellagic acid, 3,3'-di-O-methyl ellagic acid, 3'-O-methyl-3,4-methylenedioxo ellagic acid, 3'-O-methyl-3,4-methylenedioxo ellagic acid 4'-O-beta-d-glucopyranoside, and 3'-O-methyl ellagic acid 4-O-beta-d-xylopyranoside. The following additional compounds were purified by semi-preparative HPLC and tentatively identified on the basis of UV spectra, HPLC-ESI-MS and nano-ESI-MS-MS: (+)-catechin-3-O-beta-d-glucopyranoside, epicatechin-(4beta-->8)-catechin (procyanidin B(1)), epicatechin-(4beta-->8)-epicatechin (procyanidin B(2)), an (epi)catechin trimer, 3-O-methyl ellagic acid 4-O-beta-d-glucopyranoside, (-)-epicatechin 3-O-vanillate, 3,4-methylenedioxo ellagic acid 4'-O- beta-d-glucopyranoside, and 3,3'-di-O-methyl ellagic acid 4-O-beta-d-xylopyranoside. Fractionation of the raw extract by column chromatography on silicic acid yielded 10 fractions. In the hypoxanthine/xanthine oxidase antioxidant assay system, CC-9 which contained a range of polyphenols dominated by (-)-epicatechin-O-gallate proved to be the most potent antioxidant fraction (IC(50)=52 micro g/mL) in terms of ROS scavenging. In terms of XO inhibition CC-8, dominated by (epi)catechin trimer and which also contained appreciable amounts of 3'-O-methyl ellagic acid 4'-O

  3. The Effect of Plant Growth Regulators on Shoot Proliferation and Rooting of Crataegus Pseudohetrophylla Pojark. Via in Vitro Culture

    Directory of Open Access Journals (Sweden)

    F. Ahmadloo

    2015-12-01

    Full Text Available Crataegus is a tree species from Rosaceae family with medicinal, ornamental and commercial utilizations. Effect of different concentrations of plant growth regulators on shoot proliferation of Crataegus pseudohetrophylla Pojark. via in vitro culture was studied using single node explants. The grown shoots were transferred to MS medium supplemented with different concentrations of cytokinins (BAP, KIN, 2iP and Zt in combination with NAA in 30 treatments, with 3 replications and each replication included 5 explants. Data were recorded after 3 subcultures. For rooting, basal end of shoots were dipped into 300mg/l of IBA at different durations (0, 5, 10, 20, 30, 40, 50 and 60 minutes, then the dipped shoots were cultured on hormone free 1/2 VS medium. The results of analysis of variance showed that there were significant differences in all of the traits. Results indicated that the highest number of shoots (39.33 was obtained on medium containing 8 mg / l BAP plus 2 mg / l NAA. The highest shoot length (4.67 cm and leaf size (3.73 cm was achieved on 7 mg / l BAP plus 2 mg / l NAA and 2 mg / l Zt plus 1 mg / l NAA, respectively. The highest rate of rooting (33.33% and root number (4n were induced on shoots dipped for 40 minutes in 300 mg / l IBA.

  4. Isolation and characterization of a novel cis-acting sequences regulating root-specific gene from Daucus carota L.

    Institute of Scientific and Technical Information of China (English)

    LIU Yan; GUO Chang-an; REN Haibo; CHEN Fan

    2004-01-01

    Aquaporins are ubiquitous channel proteins that facilitate the transport of water across cell membranes. Most of aquaporins are represent in more than one tissues, but some of them performed highest in roots. They are belived to participate in water transport. DcRB7, a member of the aquaporin family, was isolated from somatic embryos of carrot and identified as a homologous gene of TobRB7. Further studies showed that the expression of DcRB7 was particular in carrot root. To investigate the transcription regulation of DcRB7, a 650-bp upstream sequence of DcRB7 was isolated by inverse PCR, and was fused to the β-glucuronidase (GUS) report gene. After the recombined vectors were transformed into tobacco, the expression pattern was performed by histochemical staining and the quantitative analysis of GUS activity. The results indicated that the cis-acting element of DcRB7 gene directs GUS expression not only as root-specific but also as drought inducible.

  5. Identification of Scirpus triqueter root exudates and the effects of organic acids on desorption and bioavailability of pyrene and lead in co-contaminated wetland soils.

    Science.gov (United States)

    Hou, Yunyun; Liu, Xiaoyan; Zhang, Xinying; Chen, Xiao; Tao, Kaiyun; Chen, Xueping; Liang, Xia; He, Chiquan

    2015-11-01

    Root exudates (REs) of Scirpus triqueter were extracted from the rhizosphere soil in this study. The components in the REs were identified by GC-MS. Many organic acids, such as hexadecanoic acid, pentadecanoic acid, vanillic acid, octadecanoic acid, citric acid, succinic acid, glutaric acid, and so on, were found. Batch simulated experiments were conducted to evaluate the impacts of different organic acids, such as citric acid, artificial root exudates (ARE), succinic acid, and glutaric acid in REs of S. triqueter on desorption of pyrene (PYR) and lead (Pb) in co-contaminated wetland soils. The desorption amount of PYR and Pb increased with the rise in concentrations of organic acids in the range of 0-50 g·L(-1), within shaking time of 2-24 h. The desorption effects of PYR and Pb in soils with various organic acids treatments decreased in the following order: citric acid > ARE > succinic acid > glutaric acid. The desorption rate of PYR and Pb was higher in co-contaminated soil than in single pollution soil. The impacts of organic acids in REs of S. triqueter on bioavailability of PYR and Pb suggested that organic acids enhanced the bioavailability of PYR and Pb in wetland soil, and the bioavailability effects of organic acids generally followed the same order as that of desorption effects.

  6. Identification and characterization of five new classes of chlorogenic acids in burdock (Arctium lappa L.) roots by liquid chromatography/tandem mass spectrometry.

    Science.gov (United States)

    Jaiswal, Rakesh; Kuhnert, Nikolai

    2011-01-01

    Burdock (Arcticum lappa L.) roots are used in folk medicine and also as a vegetable in Asian countries especially Japan, Korea, and Thailand. We have used LC-MS(n) (n = 2-4) to detect and characterize in burdock roots 15 quantitatively minor fumaric, succinic, and malic acid-containing chlorogenic acids, 11 of them not previously reported in nature. These comprise 3-succinoyl-4,5-dicaffeoyl or 1-succinoyl-3,4-dicaffeoylquinic acid, 1,5-dicaffeoyl-3-succinoylquinic acid, 1,5-dicaffeoyl-4-succinoylquinic acid, and 3,4-dicaffeoyl-5-succinoylquinic acid (M(r) 616); 1,3-dicaffeoyl-5-fumaroylquinic acid and 1,5-dicaffeoyl-4-fumaroylquinic acid (M(r) 614); 1,5-dicaffeoyl-3-maloylquinic acid, 1,4-dicaffeoyl-3-maloylquinic acid, and 1,5-dicaffeoyl-4-maloylquinic acid (M(r) 632); 1,3,5-tricaffeoyl-4-succinoylquinic acid (M(r) 778); 1,5-dicaffeoyl-3,4-disuccinoylquinic acid (M(r) 716); 1,5-dicaffeoyl-3-fumaroyl-4-succinoylquinic acid and 1-fumaroyl-3,5-dicaffeoyl-4-succinoylquinic acid (M(r) 714); dicaffeoyl-dimaloylquinic acid (M(r) 748); and 1,5-dicaffeoyl-3-succinoyl-4-dimaloylquinic acid (M(r) 732). All the structures have been assigned on the basis of LC-MS(n) patterns of fragmentation, relative hydrophobicity, and analogy of fragmentation patterns if compared to caffeoylquinic acids.

  7. Retrievability of calcium hydroxide intracanal medicament with three calcium chelators, ethylenediaminetetraacetic acid, citric acid, and chitosan from root canals: An in vitro cone beam computed tomography volumetric analysis

    Science.gov (United States)

    Raghu, Ramya; Pradeep, Geethu; Shetty, Ashish; Gautham, P. M.; Puneetha, P. G.; Reddy, T. V. Satyanarayana

    2017-01-01

    Aim: This study compared the amount of aqueous-based and oil-based calcium hydroxide remaining in the canal, after removal with two different chelators 17% EDTA, 20% Citric acid and 0.2% Chitosan in combination with ultrasonic agitation. Methods and Material: Cleaning and shaping of root canals of 28 mandibular premolar was done and canals were filled either with Metapex or Ca(OH)2 mixed with distilled water. Volumetric analysis was performed utilizing cone beam-computed tomography (CBCT) after seven days of incubation. Ca(OH)2 was removed using either 17% EDTA, 20% Citric acid or 0.2% Chitosan in combination with ultrasonic agitation. Statistical analysis used: Volumetric analysis was repeated and percentage difference was calculated and statistically analyzed using Kruskal-Wallis and Mann-Whitney U test. Results: All the three chelators failed to remove aqueous-based as well as oil-based Ca(OH)2 completely from the root canal. Aqueous-based Ca(OH)2 was easier to be removed than oil-based Ca(OH)2. 0.2% Chitosan in combination with ultrasonics performed better than 17% EDTA and 20% citric acid in removal of Ca(OH)2. Conclusion: Combination of 0.2% Chitosan and ultrasonic agitation results in lower amount of Ca(OH)2 remnants than 17% EDTA, 20% Citric acid irrespective of type of vehicle present in the mix. PMID:28761249

  8. Silencing of ABCC13 transporter in wheat reveals its involvement in grain development, phytic acid accumulation and lateral root formation.

    Science.gov (United States)

    Bhati, Kaushal Kumar; Alok, Anshu; Kumar, Anil; Kaur, Jagdeep; Tiwari, Siddharth; Pandey, Ajay Kumar

    2016-07-01

    Low phytic acid is a trait desired in cereal crops and can be achieved by manipulating the genes involved either in its biosynthesis or its transport in the vacuoles. Previously, we have demonstrated that the wheat TaABCC13 protein is a functional transporter, primarily involved in heavy metal tolerance, and a probable candidate gene to achieve low phytate wheat. In the current study, RNA silencing was used to knockdown the expression of TaABCC13 in order to evaluate its functional importance in wheat. Transgenic plants with significantly reduced TaABCC13 transcripts in either seeds or roots were selected for further studies. Homozygous RNAi lines K1B4 and K4G7 exhibited 34-22% reduction of the phytic acid content in the mature grains (T4 seeds). These transgenic lines were defective for spike development, as characterized by reduced grain filling and numbers of spikelets. The seeds of transgenic wheat had delayed germination, but the viability of the seedlings was unaffected. Interestingly, early emergence of lateral roots was observed in TaABCC13-silenced lines as compared to non-transgenic lines. In addition, these lines also had defects in metal uptake and development of lateral roots in the presence of cadmium stress. Our results suggest roles of TaABCC13 in lateral root initiation and enhanced sensitivity towards heavy metals. Taken together, these data demonstrate that wheat ABCC13 is functionally important for grain development and plays an important role during detoxification of heavy metals.

  9. Salicylic acid modulates arsenic toxicity by reducing its root to shoot translocation in rice (Oryza sativa L.

    Directory of Open Access Journals (Sweden)

    Amit Pal Singh

    2015-05-01

    Full Text Available Arsenic (As is posing serious health concerns in South East Asia where rice, an efficient accumulator of As, is prominent crop. Salicylic acid (SA is an important signalling molecule and plays a crucial role in resistance against biotic and abiotic stress in plants. In present study, ameliorative effect of SA against arsenate (AsV toxicity has been investigated in rice (Oryza sativa L.. Arsenate stress hampered the plant growth in terms of root, shoots length and biomass as well as it enhanced the level of H2O2 and MDA in dose dependent manner in shoot. Exogenous application of SA, reverted the growth and oxidative stress caused byAsV and significantly decreased As translocation to the shoots. Level of As in shoot was positively correlated with the expression of OsLsi2, efflux transporter responsible for root to shoot translocation of arsenic in the form of arsenite (AsIII. Salicylic acid also overcame AsV induced oxidative stress and modulated the activities of antioxidant enzymes in a differential manner in shoots. Arsenic treatment hampered the translocation of Fe in the shoot which was compensated by the SA treatment. The level of Fe in root and shoot was positively correlated with the transcript level of transporters responsible for the accumulation of Fe,OsNRAMP5 and OsFRDL1, in the root and shoot respectively. Co-application of SA was more effective than pre-treatment for reducing As accumulation as well as imposed toxicity.

  10. Rosmarinic acid is a homoserine lactone mimic produced by plants that activates a bacterial quorum-sensing regulator.

    Science.gov (United States)

    Corral-Lugo, Andrés; Daddaoua, Abdelali; Ortega, Alvaro; Espinosa-Urgel, Manuel; Krell, Tino

    2016-01-05

    Quorum sensing is a bacterial communication mechanism that controls genes, enabling bacteria to live as communities, such as biofilms. Homoserine lactone (HSL) molecules function as quorum-sensing signals for Gram-negative bacteria. Plants also produce previously unidentified compounds that affect quorum sensing. We identified rosmarinic acid as a plant-derived compound that functioned as an HSL mimic. In vitro assays showed that rosmarinic acid bound to the quorum-sensing regulator RhlR of Pseudomonas aeruginosa PAO1 and competed with the bacterial ligand N-butanoyl-homoserine lactone (C4-HSL). Furthermore, rosmarinic acid stimulated a greater increase in RhlR-mediated transcription in vitro than that of C4-HSL. In P. aeruginosa, rosmarinic acid induced quorum sensing-dependent gene expression and increased biofilm formation and the production of the virulence factors pyocyanin and elastase. Because P. aeruginosa PAO1 infection induces rosmarinic acid secretion from plant roots, our results indicate that rosmarinic acid secretion is a plant defense mechanism to stimulate a premature quorum-sensing response. P. aeruginosa is a ubiquitous pathogen that infects plants and animals; therefore, identification of rosmarinic acid as an inducer of premature quorum-sensing responses may be useful in agriculture and inform human therapeutic strategies.

  11. Graphene oxide modulates root growth of Brassica napus L. and regulates ABA and IAA concentration.

    Science.gov (United States)

    Cheng, Fan; Liu, Yu-Feng; Lu, Guang-Yuan; Zhang, Xue-Kun; Xie, Ling-Li; Yuan, Cheng-Fei; Xu, Ben-Bo

    2016-04-01

    Researchers have proven that nanomaterials have a significant effect on plant growth and development. To better understand the effects of nanomaterials on plants, Zhongshuang 11 was treated with different concentrations of graphene oxide. The results indicated that 25-100mg/l graphene oxide treatment resulted in shorter seminal root length compared with the control samples. The fresh root weight decreased when treated with 50-100mg/l graphene oxide. The graphene oxide treatment had no significant effect on the Malondialdehyde (MDA) content. Treatment with 50mg/l graphene oxide increased the transcript abundance of genes involved in ABA biosynthesis (NCED, AAO, and ZEP) and some genes involved in IAA biosynthesis (ARF2, ARF8, IAA2, and IAA3), but inhibited the transcript levels of IAA4 and IAA7. The graphene oxide treatment also resulted in a higher ABA content, but a lower IAA content compared with the control samples. The results indicated that graphene oxide modulated the root growth of Brassica napus L. and affected ABA and IAA biosynthesis and concentration.

  12. Developmentally regulated epitopes of cell surface arabinogalactan proteins and their relation to root tissue pattern formation.

    Science.gov (United States)

    Knox, J P; Linstead, P J; Peart, J; Cooper, C; Roberts, K

    1991-11-01

    Two polymorphic forms of an extracellular arabinogalactan protein (AGP1 and AGP2), obtained from the conditioned media of two carrot suspension-cultured cell lines, have been identified in terms of binding of the anti-plasma membrane antibodies JIM4 and MAC207. AGP1 and AGP2 have been used as immunogens to generate further anti-AGP monoclonal antibodies. JIM14 identified an epitope carried by AGP2 and also by glycoproteins of low molecular weight localized to the plant cell wall. In addition, further antibodies (JIM13 and JIM15) identified carbohydrate epitopes of the AGPs that also occur on plasma membrane glycoproteins and are expressed by patterns of cells that reflect cell position at the carrot root apex. Indirect immunofluorescence microscopy indicated that JIM13 recognized the surface of cells forming the epidermis and cells marking the region and axis of the future xylem. JIM15 recognized a pattern of cells directly complementary to the JIM13 pattern. The panel of anti-AGP monoclonal antibodies now available indicates groups of cells within the root meristem that may reflect an early pre-pattern of the tissues of the mature root structure and suggests extensive modulation of cell surface AGPs during cell development and the positioning of cells within the apex.

  13. Structural insights into the regulation of aromatic amino acid hydroxylation.

    Science.gov (United States)

    Fitzpatrick, Paul F

    2015-12-01

    The aromatic amino acid hydroxylases phenylalanine hydroxylase, tyrosine hydroxylase, and tryptophan hydroxylase are homotetramers, with each subunit containing a homologous catalytic domain and a divergent regulatory domain. The solution structure of the regulatory domain of tyrosine hydroxylase establishes that it contains a core ACT domain similar to that in phenylalanine hydroxylase. The isolated regulatory domain of tyrosine hydroxylase forms a stable dimer, while that of phenylalanine hydroxylase undergoes a monomer-dimer equilibrium, with phenylalanine stabilizing the dimer. These solution properties are consistent with the regulatory mechanisms of the two enzymes, in that phenylalanine hydroxylase is activated by phenylalanine binding to an allosteric site, while tyrosine hydroxylase is regulated by binding of catecholamines in the active site.

  14. The Apoplastic Copper AMINE OXIDASE1 Mediates Jasmonic Acid-Induced Protoxylem Differentiation in Arabidopsis Roots.

    Science.gov (United States)

    Ghuge, Sandip A; Carucci, Andrea; Rodrigues-Pousada, Renato A; Tisi, Alessandra; Franchi, Stefano; Tavladoraki, Paraskevi; Angelini, Riccardo; Cona, Alessandra

    2015-06-01

    Polyamines are involved in key developmental processes and stress responses. Copper amine oxidases oxidize the polyamine putrescine (Put), producing an aldehyde, ammonia, and hydrogen peroxide (H2O2). The Arabidopsis (Arabidopsis thaliana) amine oxidase gene At4g14940 (AtAO1) encodes an apoplastic copper amine oxidase expressed at the early stages of vascular tissue differentiation in roots. Here, its role in root development and xylem differentiation was explored by pharmacological and forward/reverse genetic approaches. Analysis of the AtAO1 expression pattern in roots by a promoter::green fluorescent protein-β-glucuronidase fusion revealed strong gene expression in the protoxylem at the transition, elongation, and maturation zones. Methyl jasmonate (MeJA) induced AtAO1 gene expression in vascular tissues, especially at the transition and elongation zones. Early protoxylem differentiation was observed upon MeJA treatment along with Put level decrease and H2O2 accumulation in wild-type roots, whereas Atao1 loss-of-function mutants were unresponsive to the hormone. The H2O2 scavenger N,N(1)-dimethylthiourea reversed the MeJA-induced early protoxylem differentiation in wild-type seedlings. Likewise, Put, which had no effect on Atao1 mutants, induced early protoxylem differentiation in the wild type, this event being counteracted by N,N(1)-dimethylthiourea treatment. Consistently, AtAO1-overexpressing plants showed lower Put levels and early protoxylem differentiation concurrent with H2O2 accumulation in the root zone where the first protoxylem cells with fully developed secondary wall thickenings are found. These results show that the H2O2 produced via AtAO1-driven Put oxidation plays a role in MeJA signaling leading to early protoxylem differentiation in root. © 2015 American Society of Plant Biologists. All Rights Reserved.

  15. Analysis of Organic Acids Accumulated in Kochia Scoparia Shoots and Roots by Reverse-phase High Performance Liquid Chromatography Under Salt and Alkali Stress

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Several organic acids accumulated in Kochia Scoparia shoots and roots were studied by means of reverse-phase high performance liquid chromatography with a C18 column. Five types of binary organic acids were separated. The organic acid concentrations were determined in K. Scoparia seedlings stressed by saline (NaCl) and alkaline(NaHCO3) at the same Na + concentration. Concentrations of organic acids are stimulated by alkaline because the cells will adjust their pH values through the accumulation of organic acids, when the environment is basic. The concentrations of oxalic acid and succinic acid are higher than those of other organic acids, including tartaric acid and malic acid, and the concentration of citric acid is the lowest. The concentrations of the organic acids in the roots are higher than those in the shoots under salt(NaCl) stress, but the results are opposite while the roots are under alkali (NaHCO3) stress. This indicates that there are different adaptive strategies for K. Scoparia seedlings in organic acid metabolism under salt and alkali stress.

  16. Involvement of calmodulin in regulation of primary root elongation by N-3-oxo-hexanoyl homoserine lactone in Arabidopsis thaliana

    Directory of Open Access Journals (Sweden)

    Qian eZhao

    2015-01-01

    Full Text Available Many bacteria use signal molecules of low molecular weight to monitor their local population density and to coordinate their collective behavior in a process called quorum sensing (QS. N-acyl-homoserine lactones (AHLs are the primary QS signals among Gram-negative bacteria. AHL-mediated QS plays an essential role in diverse bacterial physiological processes. Recent evidence shows that plants are able to sense bacterial AHLs and respond to them appropriately. However, little is known about the mechanism by which plants perceive and transduce the bacterial AHLs within cells. In this study, we found that the stimulatory effect of N-3-oxo-hexanoyl homoserine lactone (3OC6-HSL on primary root elongation of Arabidopsis was abolished by the calmodulin (CaM antagonists N-(6-aminohexyl-5-chloro-1-naphthalene sulfonamide (W-7 and trifluoperazine (TFP. Western-blot and ELISA analysis revealed that the concentration of CaM protein in Arabidopsis roots increased after treatment with 1 μM 3OC6-HSL. Results from quantitative RT-PCR demonstrated that the transcription of all nine CaM genes in Arabidopsis genome was up-regulated in the plants treated with 3OC6-HSL. The loss-of-function mutants of each AtCaM gene (AtCaM1-9 were insensitive to 3OC6-HSL-stimulation of primary root elongation. On the other hand, the genetic evidence showed that CaM may not participates the inhibition of primary root length caused by application of long-chained AHLs such as C10-HSL and C12-HSL. Nevertheless, our results suggest that CaM is involved in the bacterial 3OC6-HSL signaling in plant cells. These data offer new insight into the mechanism of plant response to bacterial QS signals.

  17. Root-Expressed Maize Lipoxygenase 3 Negatively Regulates Induced Systemic Resistance to Colletotrichum graminicola in Shoots

    Directory of Open Access Journals (Sweden)

    Nasie eConstantino

    2013-12-01

    Full Text Available We have previously reported that disruption of a maize root-expressed 9-lipoxygenase (9-LOX gene, ZmLOX3, results in dramatic increase in resistance to diverse leaf and stalk pathogens. Despite evident economic significance of these findings, the mechanism behind this increased resistance remained elusive. In this study, we show that increased resistance of the lox3-4 mutants is due to constitutive activation of induced systemic resistance (ISR signaling. We showed that ZmLOX3 lacked expression in leaves in response to anthracnose leaf blight pathogen Colletotrichum graminicola, but was expressed constitutively in the roots, thus prompting our hypothesis: the roots of lox3-4 mutants are the source of increased resistance in leaves. Supporting this hypothesis, treatment of wild-type plants (WT with xylem sap of lox3-4 mutant induced resistance to C. graminicola to the levels comparable to those observed in lox3-4 mutant. Moreover, treating mutants with the sap collected from WT plants partially restored the susceptibility to C. graminicola. lox3-4 mutants showed primed defense responses upon infection, which included earlier and greater induction of defense-related PAL and GST genes compared to WT. In addition to the greater expression of the octadecanoid pathway genes, lox3-4 mutant responded earlier and with a greater accumulation of H2O2 in response to C. graminicola infection or treatment with alamethicin. These findings suggest that lox3-4 mutants display constitutive ISR-like signaling. In support of this idea, root colonization by Trichoderma virens strain GV29-8 induced the same level of disease resistance in WT as the treatment with the mutant sap, but had no additional resistance effect in lox3-4 mutant. While treatment with T. virens GV29 strongly and rapidly suppressed ZmLOX3 expression in hydroponically grown WT roots, T. virens Δsml mutant, which is deficient in ISR induction, was unable to suppress expression of ZmLOX3, thus

  18. A comparative evaluation of smear layer removal by using edta, etidronic acid, and maleic acid as root canal irrigants: An in vitro scanning electron microscopic study

    Science.gov (United States)

    Kuruvilla, Aby; Jaganath, Bharath Makonahalli; Krishnegowda, Sahadev Chickmagaravalli; Ramachandra, Praveen Kumar Makonahalli; Johns, Dexton Antony; Abraham, Aby

    2015-01-01

    Aim: The purpose of this study is to evaluate and compare the efficacy of 17% EDTA, 18% etidronic acid, and 7% maleic acid in smear layer removal using scanning electron microscopic image analysis. Materials and Methods: Thirty, freshly extracted mandibular premolars were used. The teeth were decoronated to obtain working length of 17mm and instrumentation up to 40 size (K file) with 2.5% NaOCl irrigation between each file. The samples were divided into Groups I (17% ethylenediaminetetraacetic acid (EDTA)), II (18% etidronic acid), and III (7% maleic acid) containing 10 samples each. Longitudinal sectioning of the samples was done. Then the samples were observed under scanning electron microscope (SEM) at apical, middle, and coronal levels. The images were scored according to the criteria: 1. No smear layer, 2. moderate smear layer, and 3 heavy smear layer. Statistical Analysis: Data was analyzed statistically using Kruskal–Wallis analysis of variance (ANOVA) followed by Mann-Whitney U test for individual comparisons. The level for significance was set at 0.05. Results: The present study showed that all the three experimental irrigants removed the smear layer from different tooth levels (coronal, middle, and apical). Final irrigation with 7% maleic acid is more efficient than 17% EDTA and 18% etidronic acid in the removal of smear layer from the apical third of root canal. PMID:26069414

  19. The influence of electrical charge and indolebutyric acid on rooting of willow cuttings

    Directory of Open Access Journals (Sweden)

    R. Domański

    2015-06-01

    Full Text Available Willow cuttings were treated by direct electrical current (DEC, with a negative or a positive electrode inserted inside them, and with the other being outside. Both directions of DEC flow between electrodes stimulated rooting as actively as growth stimulators. The mung bean or oat coleoptile straight growth test showed that the cuttings released some growth promoters into the surrounding water. However, the simultaneous release of some undetected rooting inhibitors was not excluded. The experiment, shows the possibility of changing the chemical regulatory mechanisms of tissues by the use of weak, direct electrical current which causes, the migration of particular substance{s into or from a definite tissue or organ.

  20. New Role of Rosea1 in Regulating Anthocyanin Biosynthetic Pathway in Hairy Root of Snapdragon (Antirrhinum majus L.

    Directory of Open Access Journals (Sweden)

    An Zhang

    2013-09-01

    Full Text Available We investigated the transcriptional regulation of anthocyanin biosynthesis in hairy roots system by ectopically expressing Rosea1 and Delila and we found something different from previous research. The RT-PCR results revealed that Rosea1 could activate early and late biosynthetic genes tested, including CHS, DFR and ANS. Delila enhanced the expression of CHS weakly, but did not influence DFR or ANS. The two regulators, Rosea1 and Delila, failed to interplay each other. It was speculated that Delila would be ineffective in the absence of Rosea1, another MYB factor specifically controlling CHS may exist. This investigation provided a new way to increase anthocyanin content by over expressing a MYB factor, potentially to be used in the field of agriculture and food

  1. Auxin and Epigenetic Regulation of SKP2B, an F-Box That Represses Lateral Root Formation1[C][W][OA

    Science.gov (United States)

    Manzano, Concepción; Ramirez-Parra, Elena; Casimiro, Ilda; Otero, Sofía; Desvoyes, Bénédicte; De Rybel, Bert; Beeckman, Tom; Casero, Pedro; Gutierrez, Crisanto; C. del Pozo, Juan

    2012-01-01

    In plants, lateral roots originate from pericycle founder cells that are specified at regular intervals along the main root. Here, we show that Arabidopsis (Arabidopsis thaliana) SKP2B (for S-Phase Kinase-Associated Protein2B), an F-box protein, negatively regulates cell cycle and lateral root formation as it represses meristematic and founder cell divisions. According to its function, SKP2B is expressed in founder cells, lateral root primordia and the root apical meristem. We identified a novel motif in the SKP2B promoter that is required for its specific root expression and auxin-dependent induction in the pericycle cells. Next to a transcriptional control by auxin, SKP2B expression is regulated by histone H3.1/H3.3 deposition in a CAF-dependent manner. The SKP2B promoter and the 5′ end of the transcribed region are enriched in H3.3, which is associated with active chromatin states, over H3.1. Furthermore, the SKP2B promoter is also regulated by H3 acetylation in an auxin- and IAA14-dependent manner, reinforcing the idea that epigenetics represents an important regulatory mechanism during lateral root formation. PMID:22837358

  2. DNA Topoisomerase 1 Prevents R-loop Accumulation to Modulate Auxin-Regulated Root Development in Rice.

    Science.gov (United States)

    Shafiq, Sarfraz; Chen, Chunli; Yang, Jing; Cheng, Lingling; Ma, Fei; Widemann, Emilie; Sun, Qianwen

    2017-06-05

    R-loop structures (RNA:DNA hybrids) have important functions in many biological processes, including transcriptional regulation and genome instability among diverse organisms. DNA topoisomerase 1 (TOP1), an essential manipulator of DNA topology during RNA transcription and DNA replication processes, can prevent R-loop accumulation by removing the positive and negative DNA supercoiling that is made by RNA polymerases during transcription. TOP1 is required for plant development, but little is known about its function in preventing co-transcriptional R-loop accumulation in various biological processes in plants. Here we show that knockdown of OsTOP1 strongly affects rice development, causing defects in root architecture and gravitropism, which are the consequences of misregulation of auxin signaling and transporter genes. We found that R-loops are naturally formed at rice auxin-related gene loci, and overaccumulate when OsTOP1 is knocked down or OsTOP1 protein activity is inhibited. OsTOP1 therefore sets the accurate expression levels of auxin-related genes by preventing the overaccumulation of inherent R-loops. Our data reveal R-loops as important factors in polar auxin transport and plant root development, and highlight that OsTOP1 functions as a key to link transcriptional R-loops with plant hormone signaling, provide new insights into transcriptional regulation of hormone signaling in plants. Copyright © 2017 The Author. Published by Elsevier Inc. All rights reserved.

  3. Periodontal ligament stem cells modulate root resorption of human primary teeth via Runx2 regulating RANKL/OPG system.

    Science.gov (United States)

    Li, Bei; Zhang, Yu; Wang, Qingchao; Dong, Zhiwei; Shang, Linjuan; Wu, Lizheng; Wang, Xiaojing; Jin, Yan

    2014-10-15

    Physiological primary teeth exfoliation is a normal phenomenon during teeth development. However, retained primary teeth can often be observed in the patients with cleidocranial dysplasia (CCD) caused by mutation of Runx2. The potential regulative mechanism is still unknown. In the present study, periodontal ligament stem cells (PDLSCs) were derived from different resorbed stages of primary teeth and permanent teeth from normal patients and primary teeth from CCD patient. The proliferative, osteogenic and osteoclast-inductive capacities of PDLSCs from each group were detected. We demonstrated here that the proliferative ability of PDLSCs was reduced while the osteogenic and the osteoclast-inductive capacity of PDLSCs were enhanced during root resorption. The results also showed that PDLSCs from permanent teeth and CCD patient expressed low level of Runx2 and RANKL while high level of OPG. However, expression of Runx2 and RANKL were increased while expression of OPG was decreased in PDLSCs derived from resorbed teeth. Furthermore, Runx2 regulating the expression of RANKL and OPG and the osteoclast-inductive capacity of PDLSCs were confirmed by gain or loss of function assay. These data suggest that PDLSCs promote osteoclast differentiation via Runx2 upregulating RANKL and downregulating OPG, leading to enhanced root resorption that results in physiological exfoliation of primary teeth.

  4. Phosphorus effects on the mycelium and storage structures of an arbuscular mycorrhizal fungus as studied in the soil and roots by analysis of fatty acid signatures

    DEFF Research Database (Denmark)

    Olsson, P.A.; Bååth, E.; Jakobsen, I.

    1997-01-01

    in the extraradical mycelium was positively correlated with the level of root infection and thus decreased with increasing applications of P. The neutral lipid/phospholipid ratio indicated that at high P levels, less carbon was allocated to storage structures. At all levels of P applied, the major part of the AM......The distribution of an arbuscular mycorrhizal (AM) fungus between soil and roots, and between mycelial and storage structures, was studied by use of the fatty acid signature 16:1 omega 5. Increasing the soil phosphorus level resulted in a decrease in the level of the fatty acid 16:1 omega 5...... in the soil and roots. A similar decrease was detected by microscopic measurements of root colonization and of the length of AM fungal hyphae in the soil. The fatty acid 16:1 omega 5 was estimated from two types of lipids, phospholipids and neutral lipids, which mainly represent membrane lipids and storage...

  5. Regulation of energy metabolism by long-chain fatty acids.

    Science.gov (United States)

    Nakamura, Manabu T; Yudell, Barbara E; Loor, Juan J

    2014-01-01

    In mammals, excess energy is stored primarily as triglycerides, which are mobilized when energy demands arise. This review mainly focuses on the role of long chain fatty acids (LCFAs) in regulating energy metabolism as ligands of peroxisome proliferator-activated receptors (PPARs). PPAR-alpha expressed primarily in liver is essential for metabolic adaptation to starvation by inducing genes for beta-oxidation and ketogenesis and by downregulating energy expenditure through fibroblast growth factor 21. PPAR-delta is highly expressed in skeletal muscle and induces genes for LCFA oxidation during fasting and endurance exercise. PPAR-delta also regulates glucose metabolism and mitochondrial biogenesis by inducing FOXO1 and PGC1-alpha. Genes targeted by PPAR-gamma in adipocytes suggest that PPAR-gamma senses incoming non-esterified LCFAs and induces the pathways to store LCFAs as triglycerides. Adiponectin, another important target of PPAR-gamma may act as a spacer between adipocytes to maintain their metabolic activity and insulin sensitivity. Another topic of this review is effects of skin LCFAs on energy metabolism. Specific LCFAs are required for the synthesis of skin lipids, which are essential for water barrier and thermal insulation functions of the skin. Disturbance of skin lipid metabolism often causes apparent resistance to developing obesity at the expense of normal skin function.

  6. Salicylic acid 3-hydroxylase regulates Arabidopsis leaf longevity by mediating salicylic acid catabolism.

    Science.gov (United States)

    Zhang, Kewei; Halitschke, Rayko; Yin, Changxi; Liu, Chang-Jun; Gan, Su-Sheng

    2013-09-01

    The plant hormone salicylic acid (SA) plays critical roles in plant defense, stress responses, and senescence. Although SA biosynthesis is well understood, the pathways by which SA is catabolized remain elusive. Here we report the identification and characterization of an SA 3-hydroxylase (S3H) involved in SA catabolism during leaf senescence. S3H is associated with senescence and is inducible by SA and is thus a key part of a negative feedback regulation system of SA levels during senescence. The enzyme converts SA (with a Km of 58.29 µM) to both 2,3-dihydroxybenzoic acid (2,3-DHBA) and 2,5-DHBA in vitro but only 2,3-DHBA in vivo. The s3h knockout mutants fail to produce 2,3-DHBA sugar conjugates, accumulate very high levels of SA and its sugar conjugates, and exhibit a precocious senescence phenotype. Conversely, the gain-of-function lines contain high levels of 2,3-DHBA sugar conjugates and extremely low levels of SA and its sugar conjugates and display a significantly extended leaf longevity. This research reveals an elegant SA catabolic mechanism by which plants regulate SA levels by converting it to 2,3-DHBA to prevent SA overaccumulation. The research also provides strong molecular genetic evidence for an important role of SA in regulating the onset and rate of leaf senescence.

  7. A plasma membrane zinc transporter from ¤Medicago truncatula¤ is up-regulated in roots by Zn fertilization, yet down-regulated by arbuscular mycorrhizal colonization

    DEFF Research Database (Denmark)

    Burleigh, S.H.; Kristensen, B.K.; Bechmann, I.E.

    2003-01-01

    , but not in leaves of M. truncatula and, in contrast to all other plant Zn transporters characterized thus far, MtZIP2 was up-regulated in roots by Zn fertilization. Expression was highest in roots exposed to a toxic level of Zn. MtZIP2 expression was also examined in the roots of M. truncatula when colonized...... by the obligate plant symbiont, arbuscular mycorrhizal (AM) fungi, since AM fungi are renowned for their ability to supply plants with mineral nutrients, including Zn. Expression was downregulated in the roots of the mycorrhizal plants and was associated with a reduced level of Zn within the host plant tissues....

  8. Comparative analysis of caffeoylquinic acids and lignans in roots and seeds among various burdock (Arctium lappa) genotypes with high antioxidant activity.

    Science.gov (United States)

    Liu, Jingyi; Cai, Yi-Zhong; Wong, Ricky Ngok Shun; Lee, Calvin Kai-Fai; Tang, Sydney Chi Wai; Sze, Stephen Cho Wing; Tong, Yao; Zhang, Yanbo

    2012-04-25

    Caffeoylquinic acids and lignans in the crude extracts of both roots and seeds from different burdock ( Arctium lappa L.) genotypes were simultaneously characterized and systematically compared by LC-MS and matrix-assisted laser desorption/ionization quadrupole ion trap time-of-flight mass spectrometry (MALDI-QIT-TOF MS), and their antioxidant activities were also investigated. A total of 14 lignans were identified in burdock seeds and 12 caffeoylquinic acids in burdock roots. High levels of caffeoylquinic acids were also detected in burdock seeds, but only trace amounts of lignans were found in burdock roots. Burdock seeds contained higher concentrations of lignans and caffeoylquinic acids than burdock roots. Quantitative analysis of caffeoylquinic acids and lignans in roots and seeds of various burdock genotypes was reported for the first time. Great variations in contents of both individual and total phenolic compounds as well as antioxidant activities were found among different genotypes. Burdock as a root vegetable or medicinal plants possessed considerably stronger antioxidant activity than common vegetables and fruits.

  9. The role of γ-aminobutyric acid and its receptors in the nucleus of basal optic root in pigeons

    Institute of Scientific and Technical Information of China (English)

    付煜西; 高宏峰; 王书荣; Stephen A.George

    1997-01-01

    The effects of γ-aminobutyric acid (GABA) and its antagonists bicuculline and 2-hydroxysaclofen on neuronal firings in the nucleus of basal optic root (nBOR) in pigeons were studied by using extracellular recording and microiontophoretic techniques. The results suggest that GABA may be an inhibitory neurotransmitter or modulator within nBOR, functioning by means of main mediation of GABAA receptors and of minor mediation of GABAB receptors. Furthermore, GABA and its GABAA receptors are involved in the modulation of directional selectivity in part of nBOR neurons.

  10. Determination of Organi Acids in Root Exudates by High Performance Liquid Chromatorgraphy:Ⅰ.Develop—ment and Assessment of Chromatographic Conditions

    Institute of Scientific and Technical Information of China (English)

    SHENJIANBO; ZHANGFUSUO; 等

    1998-01-01

    Methods for determining niene low molecular-weight oragnic acids in root exudates were developed by using reversed-phase high performance liquied chromatography with UV (ultraviolet) detection at 214 nm. The mobile phase was 18 mmol L-1 kH2PO4 adjusted to pH 2.25 with phosporic acid nd the flow rate was 0.3 mL min-1,The analytical column was a reversed-phase silica based C-18 column( shim-pack CLC-ODS).The root exudates were collected through submerging the whole root system into aerated deionized water for 2 hours ,The filtered exudate solutions were concentrated to dryness by rotary evaporation at 40℃,dissolved in 10 mL mobile phase.The chromatoraphic conditions of organic acid determination were analyzed.The results showed that there was a high selectivity and sensitivity in the organic acid determination by reversed-phase high performance liquid chromatography.Coefficients of variation for organic acied determination were lower than 10% except lactic acid .The recoveries were consistently between 80.1% to 108.3% .Detection limits were approximately 0.05 to 4.5 mg L-1 for organic acids except succinic acid with the detection limit of 7.0 mg L-1 .Phosphorus deficiency may contribute to the release of organic acids in soybean root exudates especially malic,lactic and citric acids.

  11. Comparative Genomics of Regulation of Fatty Acid and Branched-chain Amino Acid Utilization in Proteobacteria

    Energy Technology Data Exchange (ETDEWEB)

    Kazakov, Alexey E.; Rodionov, Dmitry A.; Arkin, Adam Paul; Dubchak, Inna; Gelfand, Mikhail S.; Alm, Eric

    2008-10-31

    Bacteria can use branched-chain amino acids (ILV, i.e. isoleucine, leucine, valine) and fatty acids (FA) as sole carbon and energy sources convering ILV into acetyl-CoA, propanoyl-CoA and propionyl-CoA, respectively. In this work, we used the comparative genomic approach to identify candidate transcriptional factors and DNA motifs that control ILV and FA utilization pathways in proteobacteria. The metabolic regulons were characterized based on the identification and comparison of candidate transcription factor binding sites in groups of phylogenetically related genomes. The reconstructed ILV/FA regulatory network demonstrates considerable variability and involves six transcriptional factors from the MerR, TetR and GntR families binding to eleven distinct DNA motifs. The ILV degradation genes in gamma- and beta-proteobacteria are mainly regulated by anovel regulator from the MerR family (e.g., LiuR in Pseudomonas aeruginosa) (40 species), in addition, the TetR-type regulator LiuQ was identified in some beta-proteobacteria (8 species). Besides the core set of ILV utilization genes, the LiuR regulon in some lineages is expanded to include genes from other metabolic pathways, such as the glyoxylate shunt and glutamate synthase in the Shewanella species. The FA degradation genes are controlled by four regulators including FadR in gamma-proteobacteria (34 species), PsrA in gamma- and beta-proteobacteria (45 species), FadP in beta-proteobacteria (14 species), and LiuR orthologs in alpha-proteobacteria (22 species). The remarkable variability of the regulatory systems associated with the FA degradation pathway is discussed from the functional and evolutionary points of view.

  12. Effect of Boric Acid Versus Conventional Irrigation Solutions on the Bond Strength Between Fiber Post 
and Root Dentin.

    Science.gov (United States)

    Culhaoglu, Ahmet Kursad; Özcan, Erdal; Kilicarslan, Mehmet Ali; Seker, Emre

    2017-01-01

    To compare the effect of boric acid solutions of different percentages to conventional irrigation solutions on the adhesive bond strength between fiber posts and radicular dentin surface with different cement types. One hundred fifteen extracted human incisors were endodontically instrumented to a length of 14-15 mm, and 12-mm post spaces were prepared with specific drills. Cylindrical fiber posts (Panavia Post) were luted with two different composite cements (Panavia F 2.0, Panavia SA) and cut into 1-mm-thick slices. These specimens were randomly allocated to 5 groups according to the irrigant applied: 1. control, no irrigant; 2. 10 ml of 2% chlorhexidine; 3. 10 ml of 5.25% NaOCl for 5 min and 10 ml of 17% EDTA for 3 min; 4. 10 ml of 5% boric acid solution at a temperature of 55°C for 60 s; 5. 10% boric acid solution, conditions as in group 4. Bond strength was determined using the push-out test. Microscopic assessment and SEM evaluations were performed in combination with push-out tests. The push-out bond strengths of cervical segments were significantly higher than for the middle and apical segments in all groups. The type of irrigation solution used significantly affected the bond strengths of the posts. The 10% boric acid solution and EDTA + NaOCl irrigation solutions provided the highest bond strengths (p boric acid were used as irrigation agents. Boric acid solutions, especially at a concentration of 10%, can be a viable alternative to the conventional irrigants used during endodontic treatment. The extent to which the 10% boric acid solution successfully removed the smear layer and the ease of rinsing boric acid from the root surface are advantageous.

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

    Science.gov (United States)

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

    1996-09-01

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

  14. Relative abundance of chemical forms of Cu(II) and Cd(II) on soybean roots as influenced by pH, cations and organic acids

    Science.gov (United States)

    Zhou, Qin; Liu, Zhao-Dong; Liu, Yuan; Jiang, Jun; Xu, Ren-Kou

    2016-11-01

    Little information is available on chemical forms of heavy metals on integrate plant roots. KNO3 (1 M), 0.05M EDTA at pH6 and 0.01 M HCl were used sequentially to extract the exchangeable, complexed and precipitated forms of Cu(II) and Cd(II) from soybean roots and then to investigate chemical form distribution of Cu(II) and Cd(II) on soybean roots. Cu(II) and Cd(II) adsorbed on soybean roots were mainly exchangeable form, followed by complexed form, while their precipitated forms were very low under acidic conditions. Soybean roots had a higher adsorption affinity to Cu(II) than Cd(II), leading to higher toxic of Cu(II) than Cd(II). An increase in solution pH increased negative charge on soybean and thus increased exchangeable Cu(II) and Cd(II) on the roots. Ca2+, Mg2+ and NH4+ reduced exchangeable Cu(II) and Cd(II) levels on soybean roots and these cations showed greater effects on Cd(II) than Cu(II) due to greater adsorption affinity of the roots to Cu(II) than Cd(II). L-malic and citric acids decreased exchangeable and complexed Cu(II) on soybean roots. In conclusion, Cu(II) and Cd(II) mainly existed as exchangeable and complexed forms on soybean roots. Ca2+ and Mg2+ cations and citric and L-malic acids can potentially alleviate Cu(II) and Cd(II) toxicity to plants.

  15. Arabidopsis phospholipase D alpha 1-derived phosphatidic acid regulates microtubule organization and cell development under microtubule-interacting drugs treatment.

    Science.gov (United States)

    Zhang, Qun; Qu, Yana; Wang, Qing; Song, Ping; Wang, Peipei; Jia, Qianru; Guo, Jinhe

    2017-01-01

    Phospholipase D (PLD) and its product phosphatidic acid (PA) are emerging as essential regulators of cytoskeleton organization in plants. However, the underlying molecular mechanisms of PA-mediated microtubule reorganization in plants remain largely unknown. In this study, we used pharmacological and genetic approaches to analyze the function of Arabidopsis thaliana PLDα1 in the regulation of microtubule organization and cell development in response to microtubule-affecting drugs. Treatment with the microtubule-stabilizing drug paclitaxel resulted in less growth inhibition and decreased rightward slant of roots, longitudinal alignment of microtubules, and enhanced length of hypocotyl epidermal cells in the pldα1 mutant, the phenotype of which was rescued by exogenous application of PA. Moreover, the pldα1 mutant was sensitive to the microtubule-disrupting drugs oryzalin and propyzamide in terms of seedling survival ratio, left-skewing angle of roots and microtubule organization. In addition, both disruption and stabilization of microtubules induced by drugs activated PLDα1 activity. Our findings demonstrate that in A. thaliana, PLDα1/PA might regulate cell development by modulating microtubule organization in an activity-dependent manner.

  16. Cadmium Disrupts the Balance between Hydrogen Peroxide and Superoxide Radical by Regulating Endogenous Hydrogen Sulfide in the Root Tip of Brassica rapa

    Science.gov (United States)

    Lv, Wenjing; Yang, Lifei; Xu, Cunfa; Shi, Zhiqi; Shao, Jinsong; Xian, Ming; Chen, Jian

    2017-01-01

    Cd (cadmium) stress always alters the homeostasis of ROS (reactive oxygen species) including H2O2 (hydrogen sulfide) and O2•– (superoxide radical), leading to the oxidative injury and growth inhibition in plants. In addition to triggering oxidative injury, ROS has been suggested as important regulators modulating root elongation. However, whether and how Cd stress induces the inhibition of root elongation by differentially regulating endogenous H2O2 and O2•–, rather than by inducing oxidative injury, remains elusive. To address these gaps, histochemical, physiological, and biochemical approaches were applied to investigate the mechanism for Cd to fine-tune the balance between H2O2 and O2•– in the root tip of Brassica rapa. Treatment with Cd at 4 and 16 μM significantly inhibited root elongation, while only 16 μM but not 4 μM of Cd induced oxidative injury and cell death in root tip. Fluorescent and pharmaceutical tests suggested that H2O2 and O2•– played negative and positive roles, respectively, in the regulation of root elongation in the presence of Cd (4 μM) or not. Treatment with Cd at 4 μM led to the increase in H2O2 and the decrease in O2•– in root tip, which may be attributed to the up-regulation of Br_UPB1s and the down-regulation of their predicted targets (four peroxidase genes). Cd at 4 μM resulted in the increase in endogenous H2S in root tip by inducing the up-regulation of LCDs and DCDs. Treatment with H2S biosynthesis inhibitor or H2S scavenger significantly blocked Cd (4 μM)-induced increase in endogenous H2S level, coinciding with the recovery of root elongation, the altered balance between H2O2 and O2•–, and the expression of Br_UPB1s and two peroxidase genes. Taken together, it can be proposed that endogenous H2S mediated the phytotoxicity of Cd at low concentration by regulating Br_UPB1s-modulated balance between H2O2 and O2•– in root tip. Such findings shed new light on the regulatory role of endogenous H2S in

  17. Effect of Copper on Fatty-Acid Composition and Peroxidation of Lipids in the Roots of Copper Tolerant and Sensitive Silene-Cucubalus.

    NARCIS (Netherlands)

    De Vos, C.H.R.; TenBookum, W.M.; Vooijs, R.; Schat, H.; De Kok, L.J.

    1993-01-01

    The effect of high copper exposure in vivo on the lipid and fatty acid composition and lipid peroxidation was studied in the roots of plants from one copper sensitive and two copper tolerant genotypes of Silene cucubalus. At 0.5 muM Cu (control treatment) the compositions of lipids and fatty acids i

  18. Acetic acid acts as an elicitor exerting a chitosan-like effect on xanthone biosynthesis in Hypericum perforatum L. root cultures.

    Science.gov (United States)

    Valletta, Alessio; De Angelis, Giulia; Badiali, Camilla; Brasili, Elisa; Miccheli, Alfredo; Di Cocco, Maria Enrica; Pasqua, Gabriella

    2016-05-01

    Acetic acid acts as a signal molecule, strongly enhancing xanthone biosynthesis in Hypericum perforatum root cultures. This activity is specific, as demonstrated by the comparison with other short-chain monocarboxylic acids. We have recently demonstrated that Hypericum perforatum root cultures constitutively produce xanthones at higher levels than the root of the plant and that they respond to chitosan (CHIT) elicitation with a noteworthy increase in xanthone production. In the present study, CHIT was administered to H. perforatum root cultures using three different elicitation protocols, and the increase in xanthone production was evaluated. The best results (550 % xanthone increase) were obtained by subjecting the roots to a single elicitation with 200 mg l(-1) CHIT and maintaining the elicitor in the culture medium for 7 days. To discriminate the effect of CHIT from that of the solvent, control experiments were performed by administering AcOH alone at the same concentration used for CHIT solubilization. Unexpectedly, AcOH caused an increase in xanthone production comparable to that observed in response to CHIT. Feeding experiments with (13)C-labeled AcOH demonstrated that this compound was not incorporated into the xanthone skeleton. Other short-chain monocarboxylic acids (i.e., propionic and butyric acid) have little or no effect on the production of xanthones. These results indicate that AcOH acts as a specific signal molecule, able to greatly enhance xanthone biosynthesis in H. perforatum root cultures.

  19. Shifts in root-associated microbial communities of Typha latifolia growing in naphthenic acids and relationship to plant health.

    Science.gov (United States)

    Phillips, Lori A; Armstrong, Sarah A; Headley, John V; Greer, Charles W; Germida, James J

    2010-01-01

    Naphthenic acids (NAs) are a complex mixture of organic acid compounds released during the extraction of crude oil from oil sands operations. The accumulation of toxic NAs in tailings pond water (TPW) is of significant environmental concern, and phytoremediation using constructed wetlands is one remediation option being assessed. Since root-associated microorganisms are an important factor during phytoremediation of organic compounds, this study investigated the impact of NAs on the microbial communities associated with the macrophyte Typha latifolia (cattail). Denaturing gradient gel electrophoresis revealed that the impact of NAs on microbial communities was niche dependent, with endophytic communities being the most stable and bulk water communities being the least stable. The type of NA used was significant to microbial response, with commercial NAs causing greater adverse changes than TPW NAs. In general, plant beneficial bacteria such as diazotrophs were favoured in cattails grown in TPW NAs, while potentially deleterious bacteria such as denitrifying Dechlorospirillum species increased in commercial NA treatments. These findings suggest that NAs may affect plant health by impacting root-associated microbial communities. A better understanding of these impacts may allow researchers to optimize those microbial communities that support plant health, and thus further optimize wetland treatment systems.

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

    Directory of Open Access Journals (Sweden)

    Wei eLiting

    2015-06-01

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

  1. Glutathione transferase supergene family in tomato: Salt stress-regulated expression of representative genes from distinct GST classes in plants primed with salicylic acid.

    Science.gov (United States)

    Csiszár, Jolán; Horváth, Edit; Váry, Zsolt; Gallé, Ágnes; Bela, Krisztina; Brunner, Szilvia; Tari, Irma

    2014-05-01

    A family tree of the multifunctional proteins, glutathione transferases (GSTs, EC 2.5.1.18) was created in Solanum lycopersicum based on homology to known Arabidopsis GSTs. The involvement of selected SlGSTs was studied in salt stress response of tomato primed with salicylic acid (SA) or in un-primed plants by real-time qPCR. Selected tau GSTs (SlGSTU23, SlGSTU26) were up-regulated in the leaves, while GSTs from lambda, theta, dehydroascorbate reductase and zeta classes (SlGSTL3, SlGSTT2, SlDHAR5, SlGSTZ2) in the root tissues under salt stress. Priming with SA exhibited a concentration dependency; SA mitigated the salt stress injury and caused characteristic changes in the expression pattern of SlGSTs only at 10(-4) M concentration. SlGSTF4 displayed a significant up-regulation in the leaves, while the abundance of SlGSTL3, SlGSTT2 and SlGSTZ2 transcripts were enhanced in the roots of plants primed with high SA concentration. Unexpectedly, under high salinity the SlDHAR2 expression decreased in primed roots as compared to the salt-stressed plants, however, the up-regulation of SlDHAR5 isoenzyme contributed to the maintenance of DHAR activity in roots primed with high SA. The members of lambda, theta and zeta class GSTs have a specific role in salt stress acclimation of tomato, while SlGSTU26 and SlGSTF4, the enzymes with high glutathione conjugating activity, characterize a successful priming in both roots and leaves. In contrast to low concentration, high SA concentration induced those GSTs in primed roots, which were up-regulated under salt stress. Our data indicate that induction of GSTs provide a flexible tool in maintaining redox homeostasis during unfavourable conditions. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

  2. NITRIC OXIDE-ASSOCIATED PROTEIN1 (AtNOA1) is essential for salicylic acid-induced root waving in Arabidopsis thaliana.

    Science.gov (United States)

    Zhao, Xiang; Wang, Jin; Yuan, Jing; Wang, Xi-Li; Zhao, Qing-Ping; Kong, Pei-Tao; Zhang, Xiao

    2015-07-01

    Root waving responses have been attributed to both environmental and genetics factors, but the potential inducers and transducers of root waving remain elusive. Thus, the identification of novel signal elements related to root waving is an intriguing field of research. Genetic, physiological, cytological, live cell imaging, and pharmacological approaches provide strong evidence for the involvement of Arabidopsis thaliana NITRIC OXIDE-ASSOCIATED PROTEIN1 (AtNOA1) in salicylic acid (SA)-induced root waving. SA specially induced root waving, with an overall decrease in root elongation in A. thaliana, and this SA-induced response was disrupted in the Atnoa1 mutant, as well as in nonexpresser of pathogenesis-related genes 1 (npr1), which is defective in SA-mediated plant defense signal transduction, but not in npr3/4 single and double mutants. The expression assays revealed that the abundance of AtNOA1 was significantly increased by application of SA. Genetic and pharmacological analyses showed that SA-induced root waving involved an AtNOA1-dependent Ca(2+) signal transduction pathway, and PIN-FORMED2 (PIN2) -based polar auxin transport possibly plays a crucial role in this process. Our work suggests that SA signaling through NPR1 and AtNOA1 is involved in the control of root waving, which provides new insights into the mechanisms that control root growth behavior on a hard agar surface.

  3. Arabidopsis NITRILASE 1 Contributes to the Regulation of Root Growth and Development through Modulation of Auxin Biosynthesis in Seedlings.

    Science.gov (United States)

    Lehmann, Thomas; Janowitz, Tim; Sánchez-Parra, Beatriz; Alonso, Marta-Marina Pérez; Trompetter, Inga; Piotrowski, Markus; Pollmann, Stephan

    2017-01-01

    Nitrilases consist of a group of enzymes that catalyze the hydrolysis of organic cyanides. They are found ubiquitously distributed in the plant kingdom. Plant nitrilases are mainly involved in the detoxification of ß-cyanoalanine, a side-product of ethylene biosynthesis. In the model plant Arabidopsis thaliana a second group of Brassicaceae-specific nitrilases (NIT1-3) has been found. This so-called NIT1-subfamily has been associated with the conversion of indole-3-acetonitrile (IAN) into the major plant growth hormone, indole-3-acetic acid (IAA). However, apart of reported functions in defense responses to pathogens and in responses to sulfur depletion, conclusive insight into the general physiological function of the NIT-subfamily nitrilases remains elusive. In this report, we test both the contribution of the indole-3-acetaldoxime (IAOx) pathway to general auxin biosynthesis and the influence of altered nitrilase expression on plant development. Apart of a comprehensive transcriptomics approach to explore the role of the IAOx route in auxin formation, we took a genetic approach to disclose the function of NITRILASE 1 (NIT1) of A. thaliana. We show that NIT1 over-expression (NIT1ox) results in seedlings with shorter primary roots, and an increased number of lateral roots. In addition, NIT1ox plants exhibit drastic changes of both free IAA and IAN levels, which are suggested to be the reason for the observed phenotype. On the other hand, NIT2RNAi knockdown lines, capable of suppressing the expression of all members of the NIT1-subfamily, were generated and characterized to substantiate the above-mentioned findings. Our results demonstrate for the first time that Arabidopsis NIT1 has profound effects on root morphogenesis in early seedling development.

  4. 模拟酸雨对水稻根系激素含量与生长的影响%Effects of simulated acid rain on hormone concentration and growth of rice roots

    Institute of Scientific and Technical Information of China (English)

    吴玺; 梁婵娟

    2016-01-01

    weight treated with acid rain at pH 5.0 was less than those at pH 4.5, 3.5 or 2.5 by increasing concentrations of IAA and ABA, and then promoting root activity and H+?ATPase activity to regulate nutrients absorption. The IAA/ABA,GA/ABA, ZT/ABA, root activity, and root growth parameters treated with acid rain ( pH 4.5, 3.5 or 2.5) were all lower than those of the control. It shows that the root growth was inhibited because acid rain decreased the hormone concentrations to reduce the division and elongation of root cells and inhibited the root activity. After acid rain treated-seedlings being moved to the control condition for 5 days, the root activity and root growth parameters of rice seedlings treated with acid rain at pH 5.0 were close to the control. Moreover, the IAA/ABA, GA/ABA, ZT/ABA and H+?ATPase activity were higher than those measured during the exposure period. For groups treated with acid rain at pH 4.5, 3.5 or 2.5, all parameters were better than those measured during the exposure period. Results indicate that the inhibition on root growth was alleviated during the recovery period by increasing the growth?promoting hormone ( IAA, GA, ZT) concentrations, root activity and H+?ATPase activity. And the recovery degree of root growth depended on the intensity of acid rain.

  5. AHP6 inhibits cytokinin signaling to regulate the orientation of pericycle cell division during lateral root initiation.

    Directory of Open Access Journals (Sweden)

    Sofia Moreira

    Full Text Available In Arabidopsis thaliana, lateral roots (LRs initiate from anticlinal cell divisions of pericycle founder cells. The formation of LR primordia is regulated antagonistically by the phytohormones cytokinin and auxin. It has previously been shown that cytokinin has an inhibitory effect on the patterning events occurring during LR formation. However, the molecular players involved in cytokinin repression are still unknown. In a similar manner to protoxylem formation in Arabidopsis roots, in which AHP6 (ARABIDOPSIS HISTIDINE PHOSPHOTRANSFER PROTEIN 6 acts as a cytokinin inhibitor, we reveal that AHP6 also functions as a cytokinin repressor during early stages of LR development. We show that AHP6 is expressed at different developmental stages during LR formation and is required for the correct orientation of cell divisions at the onset of LR development. Moreover, we demonstrate that AHP6 influences the localization of the auxin efflux carrier PIN1, which is necessary for patterning the LR primordia. In summary, we show that the inhibition of cytokinin signaling through AHP6 is required to establish the correct pattern during LR initiation.

  6. Global regulation of reactive oxygen species scavenging genes in alfalfa root and shoot under gradual drought stress and recovery.

    Science.gov (United States)

    Kang, Yun; Udvardi, Michael

    2012-05-01

    Reactive oxygen species (ROS) production and scavenging in plants under drought stress have been studied intensively in recent years. Here we report a global analysis of gene expression for the major ROS generating and scavenging proteins in alfalfa root and shoot under gradual drought stress followed by one-day recovery. Data from two alfalfa varieties, one drought tolerant and one drought sensitive, were compared and no qualitative differences in ROS gene regulation between the two were found. Conserved, tissue-specific patterns of gene expression in response to drought were observed for several ROS-scavenging gene families, including ascorbate peroxidase, monodehydroascorbate reductase, and peroxiredoxin. In addition, differential gene expression within families was observed. Genes for the ROS-generating enzyme, NADPH oxidase were generally induced under drought, while those for glycolate oxidase were repressed. Among the ROS-scavenging protein genes, Ferritin, Cu/Zn superoxide dismutase (SOD), and the majority of the glutathione peroxidase family members were induced under drought in both roots and shoots of both alfalfa varieties. In contrast, Fe-SOD, CC-type glutaredoxins, and thoiredoxins were downregulated.

  7. Substratos e regulador vegetal no enraizamento de estacas de pitaya Substrates and plant growth regulator on the rooting of pitaya cuttings

    Directory of Open Access Journals (Sweden)

    Caio Márcio Guimarães Santos

    2010-12-01

    Full Text Available A pitaya é uma cactácea originária das florestas tropicais americanas que produz frutos exóticos bem apreciados e comercializados, principalmente no continente asiático. Contudo, ainda é uma espécie vegetal que demanda informações técnicas de cultivo nas áreas agrícolas brasileiras, motivando pesquisas em várias áreas do conhecimento. Objetivou-se avaliar diferentes substratos no enraizamento de cladódios imersos e não imersos no regulador de crescimento, ácido naftalenacético (ANA, na formação e desenvolvimento inicial de raízes em estacas de Hylocereus undatus, resultando em mudas mais vigorosas e de melhor qualidade. O experimento foi conduzido sob ripado no Departamento de Produção Vegetal - setor de Horticultura da Faculdade de Ciências Agronômicas no campus de Botucatu - UNESP. O delineamento experimental foi o inteiramente aleatorizado em esquema fatorial 4 x 2 (substratos x condições com quatro repetições. Após 60 dias da instalação do experimento foram avaliados: massa fresca e seca da parte aérea, massa fresca e seca das raízes e o comprimento da maior raiz. O crescimento e desenvolvimento radicular inicial de mudas não são influenciados pelo regulador vegetal ANA. Os substratos com a presença de areia são os mais adequados para a formação de mudas vigorosas e de boa qualidade. A mistura areia + esterco bovino proporciona maior acúmulo de fitomassa no sistema radicular de pitaya (H. undatus.The pitaya, a cactaceous species native to American tropical forests, produces well-appreciated and commercialized exotic fruits, mainly in the Asian continent. However, this plant species still requires technical information regarding cultivation in Brazilian agricultural areas, encouraging thus studies in several knowledge areas. This work aimed to evaluate the effect of different substrates on the rooting of cladodes immersed or not in the plant growth regulator naphthaleneacetic acid (ANA, as well as on

  8. Retinoic acid regulates embryonic development of mammalian submandibular salivary glands.

    Science.gov (United States)

    Wright, Diana M; Buenger, Deanna E; Abashev, Timur M; Lindeman, Robert P; Ding, Jixiang; Sandell, Lisa L

    2015-11-01

    Organogenesis is orchestrated by cell and tissue interactions mediated by molecular signals. Identification of relevant signals, and the tissues that generate and receive them, are important goals of developmental research. Here, we demonstrate that Retinoic Acid (RA) is a critical signaling molecule important for morphogenesis of mammalian submandibular salivary glands (SMG). By examining late stage RA deficient embryos of Rdh10 mutant mice we show that SMG development requires RA in a dose-dependent manner. Additionally, we find that active RA signaling occurs in SMG tissues, arising earlier than any other known marker of SMG development and persisting throughout gland morphogenesis. At the initial bud stage of development, we find RA production occurs in SMG mesenchyme, while RA signaling occurs in epithelium. We also demonstrate active RA signaling occurs in glands cultured ex vivo, and treatment with an inhibitor of RA signaling blocks growth and branching. Together these data identify RA signaling as a direct regulator of SMG organogenesis. Copyright © 2015 Elsevier Inc. All rights reserved.

  9. Metabolic regulation of the plant hormone indole-3-acetic acid

    Energy Technology Data Exchange (ETDEWEB)

    Jerry D. Cohen

    2009-11-01

    The phytohormone indole-3-acetic acid (IAA, auxin) is important for many aspects of plant growth, development and responses to the environment yet the routes to is biosynthesis and mechanisms for regulation of IAA levels remain important research questions. A critical issue concerning the biosynthesis if IAA in plants is that redundant pathways for IAA biosynthesis exist in plants. We showed that these redundant pathways and their relative contribution to net IAA production are under both developmental and environmental control. We worked on three fundamental problems related to how plants get their IAA: 1) An in vitro biochemical approach was used to define the tryptophan dependent pathway to IAA using maize endosperm, where relatively large amounts of IAA are produced over a short developmental period. Both a stable isotope dilution and a protein MS approach were used to identify intermediates and enzymes in the reactions. 2) We developed an in vitro system for analysis of tryptophan-independent IAA biosynthesis in maize seedlings and we used a metabolite profiling approach to isolate intermediates in this reaction. 3) Arabidopsis contains a small family of genes that encode potential indolepyruvate decarboxylase enzymes. We cloned these genes and studied plants that are mutant in these genes and that over-express each member in the family in terms of the level and route of IAA biosynthesis. Together, these allowed further development of a comprehensive picture of the pathways and regulatory components that are involved in IAA homeostasis in higher plants.

  10. Retinoic acid regulates the expression of photoreceptor transcription factor NRL.

    Science.gov (United States)

    Khanna, Hemant; Akimoto, Masayuki; Siffroi-Fernandez, Sandrine; Friedman, James S; Hicks, David; Swaroop, Anand

    2006-09-15

    NRL (neural retina leucine zipper) is a key basic motif-leucine zipper (bZIP) transcription factor, which orchestrates rod photoreceptor differentiation by activating the expression of rod-specific genes. The deletion of Nrl in mice results in functional cones that are derived from rod precursors. However, signaling pathways modulating the expression or activity of NRL have not been elucidated. Here, we show that retinoic acid (RA), a diffusible factor implicated in rod development, activates the expression of NRL in serum-deprived Y79 human retinoblastoma cells and in primary cultures of rat and porcine photoreceptors. The effect of RA is mimicked by TTNPB, a RA receptor agonist, and requires new protein synthesis. DNaseI footprinting and electrophoretic mobility shift assays (EMSA) using bovine retinal nuclear extract demonstrate that RA response elements (RAREs) identified within the Nrl promoter bind to RA receptors. Furthermore, in transiently transfected Y79 and HEK293 cells the activity of Nrl-promoter driving a luciferase reporter gene is induced by RA, and this activation is mediated by RAREs. Our data suggest that signaling by RA via RA receptors regulates the expression of NRL, providing a framework for delineating early steps in photoreceptor cell fate determination.

  11. Hepatic oleate regulates adipose tissue lipogenesis and fatty acid oxidation.

    Science.gov (United States)

    Burhans, Maggie S; Flowers, Matthew T; Harrington, Kristin R; Bond, Laura M; Guo, Chang-An; Anderson, Rozalyn M; Ntambi, James M

    2015-02-01

    Hepatic steatosis is associated with detrimental metabolic phenotypes including enhanced risk for diabetes. Stearoyl-CoA desaturases (SCDs) catalyze the synthesis of MUFAs. In mice, genetic ablation of SCDs reduces hepatic de novo lipogenesis (DNL) and protects against diet-induced hepatic steatosis and adiposity. To understand the mechanism by which hepatic MUFA production influences adipose tissue stores, we created two liver-specific transgenic mouse models in the SCD1 knockout that express either human SCD5 or mouse SCD3, that synthesize oleate and palmitoleate, respectively. We demonstrate that hepatic de novo synthesized oleate, but not palmitoleate, stimulate hepatic lipid accumulation and adiposity, reversing the protective effect of the global SCD1 knockout under lipogenic conditions. Unexpectedly, the accumulation of hepatic lipid occurred without induction of the hepatic DNL program. Changes in hepatic lipid composition were reflected in plasma and in adipose tissue. Importantly, endogenously synthesized hepatic oleate was associated with suppressed DNL and fatty acid oxidation in white adipose tissue. Regression analysis revealed a strong correlation between adipose tissue lipid fuel utilization and hepatic and adipose tissue lipid storage. These data suggest an extrahepatic mechanism where endogenous hepatic oleate regulates lipid homeostasis in adipose tissues.

  12. Enrichment of the Glycyrrhizic Acid from Licorice Roots (Glycyrrhiza glabra L. by Isoelectric Focused Adsorptive Bubble Chromatography

    Directory of Open Access Journals (Sweden)

    Eyyüp Karaoğul

    2016-01-01

    Full Text Available The main aim of this study was to enrich glycyrrhizic acid ammonium salt known as one of the main compounds of licorice roots (Glycyrrhiza glabra L. by isoelectric focused adsorptive bubble separation technique with different foaming agents. In the experiments, four bubble separation parameters were used with β-lactoglobulin, albumin bovine, and starch (soluble preferred as foaming agents and without additives. The enrichment of glycyrrhizic acid ammonium salt into the foam was influenced by different additive substances. The results showed that highest enrichment values were obtained from β-lactoglobulin as much as 368.3 times. The lowest enrichment values (5.9 times were determined for the application without additive. After enrichment, each experiment of glycyrrhizic acid ammonium salt confirmed that these substances could be quantitatively enriched into the collection vessel with isoelectric focused adsorptive bubble separation technique. The transfer of glycyrrhizic acid ammonium salt into the foam from standard solution in the presence of additive was more efficient than aqueous licorice extract.

  13. Up-regulation of brain-derived neurotrophic factor in the dorsal root ganglion of the rat bone cancer pain model

    Directory of Open Access Journals (Sweden)

    Tomotsuka N

    2014-07-01

    Full Text Available Naoto Tomotsuka,1 Ryuji Kaku,1 Norihiko Obata,1 Yoshikazu Matsuoka,1 Hirotaka Kanzaki,2 Arata Taniguchi,1 Noriko Muto,1 Hiroki Omiya,1 Yoshitaro Itano,1 Tadasu Sato,3 Hiroyuki Ichikawa,3 Satoshi Mizobuchi,1 Hiroshi Morimatsu1 1Department of Anesthesiology and Resuscitology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan; 2Department of Pharmacy, Okayama University Hospital, Okayama, Japan; 3Department of Oral and Craniofacial Anatomy, Tohoku University Graduate School of Dentistry, Sendai, Japan Abstract: Metastatic bone cancer causes severe pain, but current treatments often provide insufficient pain relief. One of the reasons is that mechanisms underlying bone cancer pain are not solved completely. Our previous studies have shown that brain-derived neurotrophic factor (BDNF, known as a member of the neurotrophic family, is an important molecule in the pathological pain state in some pain models. We hypothesized that expression changes of BDNF may be one of the factors related to bone cancer pain; in this study, we investigated changes of BDNF expression in dorsal root ganglia in a rat bone cancer pain model. As we expected, BDNF mRNA (messenger ribonucleic acid and protein were significantly increased in L3 dorsal root ganglia after intra-tibial inoculation of MRMT-1 rat breast cancer cells. Among the eleven splice-variants of BDNF mRNA, exon 1–9 variant increased predominantly. Interestingly, the up-regulation of BDNF is localized in small neurons (mostly nociceptive neurons but not in medium or large neurons (non-nociceptive neurons. Further, expression of nerve growth factor (NGF, which is known as a specific promoter of BDNF exon 1–9 variant, was significantly increased in tibial bone marrow. Our findings suggest that BDNF is a key molecule in bone cancer pain, and NGF-BDNF cascade possibly develops bone cancer pain. Keywords: BDNF, bone cancer pain, chronic pain, nerve growth

  14. Noninvasive microelectrode ion flux estimation technique (MIFE) for the study of the regulation of root membrane transport by cyclic nucleotides

    KAUST Repository

    Ordoñez, Natalia Maria

    2013-09-03

    Changes in ion permeability and subsequently intracellular ion concentrations play a crucial role in intracellular and intercellular communication and, as such, confer a broad array of developmental and adaptive responses in plants. These changes are mediated by the activity of plasma-membrane based transport proteins many of which are controlled by cyclic nucleotides and/or other signaling molecules. The MIFE technique for noninvasive microelectrode ion flux measuring allows concurrent quantification of net fluxes of several ions with high spatial (μm range) and temporal (ca. 5 s) resolution, making it a powerful tool to study various aspects of downstream signaling events in plant cells. This chapter details basic protocols enabling the application of the MIFE technique to study regulation of root membrane transport in general and cyclic nucleotide mediated transport in particular. © Springer Science+Business Media New York 2013.

  15. Comprehensive transcriptome analysis unravels the existence of crucial genes regulating primary metabolism during adventitious root formation in Petunia hybrida.

    Directory of Open Access Journals (Sweden)

    Amirhossein Ahkami

    Full Text Available To identify specific genes determining the initiation and formation of adventitious roots (AR, a microarray-based transcriptome analysis in the stem base of the cuttings of Petunia hybrida (line W115 was conducted. A microarray carrying 24,816 unique, non-redundant annotated sequences was hybridized to probes derived from different stages of AR formation. After exclusion of wound-responsive and root-regulated genes, 1,354 of them were identified which were significantly and specifically induced during various phases of AR formation. Based on a recent physiological model distinguishing three metabolic phases in AR formation, the present paper focuses on the response of genes related to particular metabolic pathways. Key genes involved in primary carbohydrate metabolism such as those mediating apoplastic sucrose unloading were induced at the early sink establishment phase of AR formation. Transcriptome changes also pointed to a possible role of trehalose metabolism and SnRK1 (sucrose non-fermenting 1- related protein kinase in sugar sensing during this early step of AR formation. Symplastic sucrose unloading and nucleotide biosynthesis were the major processes induced during the later recovery and maintenance phases. Moreover, transcripts involved in peroxisomal beta-oxidation were up-regulated during different phases of AR formation. In addition to metabolic pathways, the analysis revealed the activation of cell division at the two later phases and in particular the induction of G1-specific genes in the maintenance phase. Furthermore, results point towards a specific demand for certain mineral nutrients starting in the recovery phase.

  16. Transcriptomic Insight in the Control of Legume Root Secondary Infection by the Sinorhizobium meliloti Transcriptional Regulator Clr

    Directory of Open Access Journals (Sweden)

    Lan Zou

    2017-07-01

    Full Text Available The cAMP-dependent transcriptional regulator Clr of Sinorhizobium meliloti regulates the overall number of infection events on Medicago roots by a so-far unknown mechanism requiring smc02178, a Clr-target gene of unknown function. In order to shed light on the mode of action of Clr on infection and potentially reveal additional biological functions for Clr, we inventoried genomic Clr target genes by transcriptome profiling. We have found that Clr positively controls the synthesis of cAMP-dependent succinoglycan as well as the expression of genes involved in the synthesis of a so-far unknown polysaccharide compound. In addition, Clr activated expression of 24 genes of unknown function in addition to smc02178. Genes negatively controlled by Clr were mainly involved in swimming motility and chemotaxis. Functional characterization of two novel Clr-activated genes of unknown function, smb20495 and smc02177, showed that their expression was activated by the same plant signal as smc02178 ex planta. In planta, however, symbiotic expression of smc02177 proved independent of clr. Both smc02177 and smb20495 genes were strictly required for the control of secondary infection on M. sativa. None of the three smc02177, smc02178 and smb20495 genes were needed for plant signal perception. Altogether this work provides a refined view of the cAMP-dependent Clr regulon of S. meliloti. We specifically discuss the possible roles of smc02177, smc02178, smb20495 genes and other Clr-controlled genes in the control of secondary infection of Medicago roots.

  17. Antimicrobial and cytotoxic effects of phosphoric acid solution compared to other root canal irrigants

    Directory of Open Access Journals (Sweden)

    Maíra PRADO

    2015-04-01

    Full Text Available Phosphoric acid has been suggested as an irrigant due to its effectiveness in removing the smear layer. Objectives : The purpose of this study was to compare the antimicrobial and cytotoxic effects of a 37% phosphoric acid solution to other irrigants commonly used in endodontics. Material and Methods : The substances 37% phosphoric acid, 17% EDTA, 10% citric acid, 2% chlorhexidine (solution and gel, and 5.25% NaOCl were evaluated. The antimicrobial activity was tested against Candida albicans, Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, Actinomyces meyeri, Parvimonas micra, Porphyromonas gingivalis, and Prevotella nigrescens according to the agar diffusion method. The cytotoxicity of the irrigants was determined by using the MTT assay. Results : Phosphoric acid presented higher antimicrobial activity compared to the other tested irrigants. With regard to the cell viability, this solution showed results similar to those with 5.25% NaOCl and 2% chlorhexidine (gel and solution, whereas 17% EDTA and 10% citric acid showed higher cell viability compared to other irrigants. Conclusion : Phosphoric acid demonstrated higher antimicrobial activity and cytotoxicity similar to that of 5.25% NaOCl and 2% chlorhexidine (gel and solution.

  18. Antimicrobial and cytotoxic effects of phosphoric acid solution compared to other root canal irrigants.

    Science.gov (United States)

    Prado, Maíra; Silva, Emmanuel João Nogueira Leal da; Duque, Thais Mageste; Zaia, Alexandre Augusto; Ferraz, Caio Cezar Randi; Almeida, José Flávio Affonso de; Gomes, Brenda Paula Figueiredo de Almeida

    2015-01-01

    Phosphoric acid has been suggested as an irrigant due to its effectiveness in removing the smear layer. The purpose of this study was to compare the antimicrobial and cytotoxic effects of a 37% phosphoric acid solution to other irrigants commonly used in endodontics. The substances 37% phosphoric acid, 17% EDTA, 10% citric acid, 2% chlorhexidine (solution and gel), and 5.25% NaOCl were evaluated. The antimicrobial activity was tested against Candida albicans, Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, Actinomyces meyeri, Parvimonas micra, Porphyromonas gingivalis, and Prevotella nigrescens according to the agar diffusion method. The cytotoxicity of the irrigants was determined by using the MTT assay. Phosphoric acid presented higher antimicrobial activity compared to the other tested irrigants. With regard to the cell viability, this solution showed results similar to those with 5.25% NaOCl and 2% chlorhexidine (gel and solution), whereas 17% EDTA and 10% citric acid showed higher cell viability compared to other irrigants. Phosphoric acid demonstrated higher antimicrobial activity and cytotoxicity similar to that of 5.25% NaOCl and 2% chlorhexidine (gel and solution).

  19. Rooting of herbaceous minicuttings of peach rootstock under effect of indolebutyric acid (IBA

    Directory of Open Access Journals (Sweden)

    Cari Rejane Fiss Timm

    2015-02-01

    Full Text Available The use of rootstocks resulting from sexual propagation is a major problem that peach crop has in Brazil, reflecting the lack of plant homogeneity, which compromises the productivity of orchards. The clonal propagation is a promising alternative for the production of homogeneous seedlings with low cost and speed, as well as the maintenance of important agronomic characteristics. Therefore, the study aimed to assess the feasibility of propagation of rootstocks of Nemared, Flordaguard and Okinawa peach cultivars through herbaceous minicuttings, testing different concentrations of IBA (0; 1,000; 2,000; and 3,000mg.L-1. The minicuttings were immersed in the solution for five seconds and, then, placed in clear plastic containers containing medium grained vermiculite. The experiment was conducted with four replications of 20 minicuttings in the greenhouse. In 45 days, it was observed that Nemared obtained 76% of rooting with 1,000 mg.L-1of IBA, not differing from Flordaguard with 66%. The estimated dose of IBA for maximum rooting was 1,590 mg.L-1.

  20. The Root Growth-Regulating Brevicompanine Natural Products Modulate the Plant Circadian Clock.

    Science.gov (United States)

    de Montaigu, Amaury; Oeljeklaus, Julian; Krahn, Jan H; Suliman, Mohamed N S; Halder, Vivek; de Ansorena, Elisa; Nickel, Sabrina; Schlicht, Markus; Plíhal, Ondřej; Kubiasová, Karolina; Radová, Lenka; Kracher, Barbara; Tóth, Réka; Kaschani, Farnusch; Coupland, George; Kombrink, Erich; Kaiser, Markus

    2017-06-16

    Plant growth regulating properties of brevicompanines (Brvs), natural products of the fungus Penicillium brevicompactum, have been known for several years, but further investigations into the molecular mechanism of their bioactivity have not been performed. Following chemical synthesis of brevicompanine derivatives, we studied their activity in the model plant Arabidopsis by a combination of plant growth assays, transcriptional profiling, and numerous additional bioassays. These studies demonstrated that brevicompanines cause transcriptional misregulation of core components of the circadian clock, whereas other biological read-outs were not affected. Brevicompanines thus represent promising chemical tools for investigating the regulation of the plant circadian clock. In addition, our study also illustrates the potential of an unbiased -omics-based characterization of bioactive compounds for identifying the often cryptic modes of action of small molecules.

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

    DEFF Research Database (Denmark)

    Brodersen, Klaus Peter; Petersen, Morten; Nielsen, Henrik Bjørn

    2006-01-01

    Arabidopsis MPK4 has been implicated in plant defense regulation because mpk4 knockout plants exhibit constitutive activation of salicylic acid (SA)-dependent defenses, but fail to induce jasmonic acid (JA) defense marker genes in response to JA. We show here that mpk4 mutants are also defective...

  2. The bHLH transcription factor POPEYE regulates response to iron deficiency in Arabidopsis roots.

    Science.gov (United States)

    Long, Terri A; Tsukagoshi, Hironaka; Busch, Wolfgang; Lahner, Brett; Salt, David E; Benfey, Philip N

    2010-07-01

    Global population increases and climate change underscore the need for better comprehension of how plants acquire and process nutrients such as iron. Using cell type-specific transcriptional profiling, we identified a pericycle-specific iron deficiency response and a bHLH transcription factor, POPEYE (PYE), that may play an important role in this response. Functional analysis of PYE suggests that it positively regulates growth and development under iron-deficient conditions. Chromatin immunoprecipitation-on-chip analysis and transcriptional profiling reveal that PYE helps maintain iron homeostasis by regulating the expression of known iron homeostasis genes and other genes involved in transcription, development, and stress response. PYE interacts with PYE homologs, including IAA-Leu Resistant3 (ILR3), another bHLH transcription factor that is involved in metal ion homeostasis. Moreover, ILR3 interacts with a third protein, BRUTUS (BTS), a putative E3 ligase protein, with metal ion binding and DNA binding domains, which negatively regulates the response to iron deficiency. PYE and BTS expression is also tightly coregulated. We propose that interactions among PYE, PYE homologs, and BTS are important for maintaining iron homeostasis under low iron conditions.

  3. Arabidopsis ERF1 Mediates Cross-Talk between Ethylene and Auxin Biosynthesis during Primary Root Elongation by Regulating ASA1 Expression.

    Directory of Open Access Journals (Sweden)

    Jie-Li Mao

    2016-01-01

    Full Text Available The gaseous phytohormone ethylene participates in the regulation of root growth and development in Arabidopsis. It is known that root growth inhibition by ethylene involves auxin, which is partially mediated by the action of the WEAK ETHYLENE INSENSITIVE2/ANTHRANILATE SYNTHASE α1 (WEI2/ASA1, encoding a rate-limiting enzyme in tryptophan (Trp biosynthesis, from which auxin is derived. However, the molecular mechanism by which ethylene decreases root growth via ASA1 is not understood. Here we report that the ethylene-responsive AP2 transcription factor, ETHYLENE RESPONSE FACTOR1 (ERF1, plays an important role in primary root elongation of Arabidopsis. Using loss- and gain-of-function transgenic lines as well as biochemical analysis, we demonstrate that ERF1 can directly up-regulate ASA1 by binding to its promoter, leading to auxin accumulation and ethylene-induced inhibition of root growth. This discloses one mechanism linking ethylene signaling and auxin biosynthesis in Arabidopsis roots.

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

    Science.gov (United States)

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

    2017-01-01

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

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

    Science.gov (United States)

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

    2015-06-01

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

  6. Effect of ammonium sulfate, ammonium chloride and root-zone acidity on inorganic ion content of tobacco

    Science.gov (United States)

    Vessey, J. K.; Raper, C. D. Jr; Henry, L. T.; Raper CD, J. r. (Principal Investigator)

    1990-01-01

    Tobacco plants (Nicotiana tabacum L. cv NC82) were supplied with (NH4)2SO4 or NH4Cl at root-zone pH of 6.0 and 4.5 in hydroponic culture for 28 days. Dry matter accumulation, total N and C content, and leaf area and number were not affected by the NH4+ source or root-zone pH. Plants supplied with NH4Cl accumulated up to 1.2 mM Cl g DW-1, but accumulated 37% less inorganic H2PO4- and 47% less SO4(2-) than plants supplied with (NH4)2SO4. The large Cl- accumulation resulted in NH4Cl- supplied plants having a 31% higher inorganic anion (NO3-, H2, PO4-, SO4(2-), and Cl-) charge. This higher inorganic anion charge in the NH4Cl-supplied plants was balanced by a similar increase in K+ charge. Plants supplied with NH4Cl accumulated greater concentrations of Cl- in leaves (up to 5.1% of DW) than plants supplied with (NH4)2SO4 (less than -% DW). Despite the high Cl- concentration of leaves in NH4Cl supplied plants, these plants showed no symptoms of Cl- toxicity. This demonstrates that toxicity symptoms are not due solely to an interaction between high Cl- concentration in tissue and NH4+ nutrition. The increase in root-zone acidity to pH 4.5 from 6.0 did not induce toxicity symptoms.

  7. Regulation of Connexin-Based Channels by Fatty Acids

    Science.gov (United States)

    Puebla, Carlos; Retamal, Mauricio A.; Acuña, Rodrigo; Sáez, Juan C.

    2017-01-01

    In this mini-review, we briefly summarize the current knowledge about the effects of fatty acids (FAs) on connexin-based channels, as well as discuss the limited information about the impact FAs may have on pannexins (Panxs). FAs regulate diverse cellular functions, some of which are explained by changes in the activity of channels constituted by connexins (Cxs) or Panxs, which are known to play critical roles in maintaining the functional integrity of diverse organs and tissues. Cxs are transmembrane proteins that oligomerize into hexamers to form hemichannels (HCs), which in turn can assemble into dodecamers to form gap junction channels (GJCs). While GJCs communicate the cytoplasm of contacting cells, HCs serve as pathways for the exchange of ions and small molecules between the intra and extracellular milieu. Panxs, as well as Cx HCs, form channels at the plasma membrane that enable the interchange of molecules between the intra and extracellular spaces. Both Cx- and Panx-based channels are controlled by several post-translational modifications. However, the mechanism of action of FAs on these channels has not been described in detail. It has been shown however that FAs frequently decrease GJC-mediated cell-cell communication. The opposite effect also has been described for HC or Panx-dependent intercellular communication, where, the acute FA effect can be reversed upon washout. Additionally, changes in GJCs mediated by FAs have been associated with post-translational modifications (e.g., phosphorylation), and seem to be directly related to chemical properties of FAs (e.g., length of carbon chain and/or degree of saturation), but this possible link remains poorly understood. PMID:28174541

  8. Regulation of Connexin-Based Channels by Fatty Acids.

    Science.gov (United States)

    Puebla, Carlos; Retamal, Mauricio A; Acuña, Rodrigo; Sáez, Juan C

    2017-01-01

    In this mini-review, we briefly summarize the current knowledge about the effects of fatty acids (FAs) on connexin-based channels, as well as discuss the limited information about the impact FAs may have on pannexins (Panxs). FAs regulate diverse cellular functions, some of which are explained by changes in the activity of channels constituted by connexins (Cxs) or Panxs, which are known to play critical roles in maintaining the functional integrity of diverse organs and tissues. Cxs are transmembrane proteins that oligomerize into hexamers to form hemichannels (HCs), which in turn can assemble into dodecamers to form gap junction channels (GJCs). While GJCs communicate the cytoplasm of contacting cells, HCs serve as pathways for the exchange of ions and small molecules between the intra and extracellular milieu. Panxs, as well as Cx HCs, form channels at the plasma membrane that enable the interchange of molecules between the intra and extracellular spaces. Both Cx- and Panx-based channels are controlled by several post-translational modifications. However, the mechanism of action of FAs on these channels has not been described in detail. It has been shown however that FAs frequently decrease GJC-mediated cell-cell communication. The opposite effect also has been described for HC or Panx-dependent intercellular communication, where, the acute FA effect can be reversed upon washout. Additionally, changes in GJCs mediated by FAs have been associated with post-translational modifications (e.g., phosphorylation), and seem to be directly related to chemical properties of FAs (e.g., length of carbon chain and/or degree of saturation), but this possible link remains poorly understood.

  9. Enzymatic oxalic acid regulation correlated with wood degradation in four brown-rot fungi

    Science.gov (United States)

    Anne Christine Steenkjær Hastrup; Frederick Green III; Patricia K. Lebow; Bo Jensen

    2012-01-01

    Oxalic acid is a key component in the initiation of brown-rot decay and it has been suggested that it plays multiple roles during the degradation process. Oxalic acid is accumulated to varying degrees among brown-rot fungi; however, details on active regulation are scarce. The accumulation of oxalic acid was measured in this study from wood degraded by the four brown-...

  10. Production of Salvianolic Acid B in Roots of Salvia miltiorrhiza (Danshen During the Post-Harvest Drying Process

    Directory of Open Access Journals (Sweden)

    Guo-Jun Zhou

    2012-02-01

    Full Text Available Drying is the most common and fundamental procedure in the post-harvest processing which contributes to the quality and valuation of medicinal plants. However, attention to and research work on this aspect is relatively poor. In this paper, we reveal dynamic variations of concentrations of five major bioactive components, namely salvianolic acid B (SaB, dihydrotanshinone I, cryptotanshinone, tanshinone I and tanshinone IIA, in roots of Salvia miltiorrhiza (Dashen during the drying process at different oven temperatures. A minor amount of SaB was found in fresh materials while an noticeable increase in SaB was detected in drying at 50~160 °C. The maximal value occured after 40 min of drying at 130 °C and its variation showed a reverse V-shaped curve. Production of SaB exhibited a significant positive correlation with drying temperatures and a significant negative correlation with sample moistures. The amounts of tanshinones were nearly doubled in the early stage of drying and their variations showed similar changing trends with drying temperatures and sample moistures. The results supported our speculation that postharvest fresh plant materials, especially roots, were still physiologically active organs and would exhibit a series of anti-dehydration mechanisms including production of related secondary metabolites at the early stage of dehydration. Hence, the proper design of drying processes could contribute to promoting rather than reducing the quality of Danshen and other similar medicinal plants.

  11. [Regulating acid stress resistance of lactic acid bacteria--a review].

    Science.gov (United States)

    Wu, Chongde; Huang, Jun; Zhou, Rongqing

    2014-07-04

    As cell factories, lactic acid bacteria are widely used in food, agriculture, pharmaceutical and other industries. Acid stress is one the important survival challenges encountered by lactic acid bacteria both in fermentation process and in the gastrointestinal tract. Recently, the development of systems biology and metabolic engineering brings unprecedented opportunity for further elucidating the acid tolerance mechanisms and improving the acid stress resistance of lactic acid bacteria. This review addresses physiological mechanisms of lactic acid bacteria during acid stress. Moreover, strategies to improve the acid stress resistance of lactic acid were proposed.

  12. Ozone and simulated acid rain effects on growth root hydraulic conductivity, and photosynthesis of red spruce

    Energy Technology Data Exchange (ETDEWEB)

    Lee, W.S.; Chevone, B.I.; Seiler, J.R.

    1987-04-01

    Three-year-old red spruce seedlings were exposed to ozone (O/sub 3/) at 0.00 (control) or 0.10 ppm, 4 hr/d, 3 d/wk in combination with simulated rain (pH 3.0 or 5.6, 1 hr/d, 2 d/wk at 0.75 cm/hr) for 10 wks. All seedlings were submitted to two drought cycles after the 10-wk-treatment. O/sub 3/ significantly decreased root hydraulic conductivity (Lp) by 21% after 10 wks across all rain pHs. The reduction of Lp in seedlings treated with O/sub 3/ was enhanced by drought stress. Rain pH alone did not affect Lp during the 10-wks-exposure and drought cycles. However, the O/sub 3/ effect on Lp was more severe at pH 5.6 than at pH 3.0. Rain at pH 3.0 stimulated shoot height growth by 31% compared with pH 5.6 across all O/sub 3/ treatments. However, root, shoot, and total dry weight of seedlings were not changed by any treatments. Neither O/sub 3/ nor rain pH affected net photosynthetic (P/sub i/) response to branch water potential in plants subjected to one or two drought cycles. However, P/sub i/ was less sensitive to water potential after two drought cycles, indicating physiological adjustment to drought stress.

  13. The effect pathway of retinoic acid through regulation of retinoic acid receptor in gastric cancer cells

    Institute of Scientific and Technical Information of China (English)

    Su Liu; Qiao Wu; Zheng-Ming Chen; Wen-Jin Su

    2001-01-01

    AIM To evaluate the role of RARa gene in mediating the growth inhibitory effect of ail-trans retinoic acid (ATRA)on gastric cancer cells.``METHODS The expression levels of retinoic acid receptors (RARs) in gastric cancer cells were detected by Northern blot. Transient transfection and chlorophenicol acetyl transferase (CAT) assay were used to show the transcriptional activity of β retinoic acid response element (βRARE) and AP-l activity. Cell growth inhibition was determined by MTT assay and anchorage-independent growth assay, respectively. Stable transfection was performed by the method of Lipofectamine, and the cells were screened by G418.``RESULTS ATRA could induce expression level of RARα in MGC80-3, BGCC8823 and SGC-7901 cells obviously,resulting in growth inhibition of these cell lines. After sense RARa gene was transfected into MKN-45 cells that expressed rather Iow level of RARα and could not be induced by ATRA, the cell growth was inhibited by ATRA markedly. In contrast, when antisense RARα gene was transfected into BGC-825 cells, a little inhibitory effect by ATRA was seen, compared with the parallel BGC-823cells. In transient transfection assay, ATRA effectively induced transcriptional activity of βRARE in MGC80-3,BGC.823, SGC-7902 and MKN/RARa cell lines, but not in MKN-45 and BGC/aRARa cell lines. Similar results were observed in measuring anti-AP-l activity by ATRA in these cancer cell lines.``CONCLUSION ATRA inhibits the growth of gastric cancer cells by up-regulating the level of RARa; RARa is the major mediator of ATRA action in gastric cancer cells; and adequate level of RAPa is required for ATRA effect on gastric cancer cells.``

  14. FGF and BMP derived from dorsal root ganglia regulate blastema induction in limb regeneration in Ambystoma mexicanum.

    Science.gov (United States)

    Satoh, Akira; Makanae, Aki; Nishimoto, Yurie; Mitogawa, Kazumasa

    2016-09-01

    Urodele amphibians have a remarkable organ regeneration ability that is regulated by neural inputs. The identification of these neural inputs has been a challenge. Recently, Fibroblast growth factor (Fgf) and Bone morphogenic protein (Bmp) were shown to substitute for nerve functions in limb and tail regeneration in urodele amphibians. However, direct evidence of Fgf and Bmp being secreted from nerve endings and regulating regeneration has not yet been shown. Thus, it remained uncertain whether they were the nerve factors responsible for successful limb regeneration. To gather experimental evidence, the technical difficulties involved in the usage of axolotls had to be overcome. We achieved this by modifying the electroporation method. When Fgf8-AcGFP or Bmp7-AcGFP was electroporated into the axolotl dorsal root ganglia (DRG), GFP signals were detectable in the regenerating limb region. This suggested that Fgf8 and Bmp7 synthesized in neural cells in the DRG were delivered to the limbs through the long axons. Further knockdown experiments with double-stranded RNA interference resulted in impaired limb regeneration ability. These results strongly suggest that Fgf and Bmp are the major neural inputs that control the organ regeneration ability.

  15. Regulation of Nav1.7: A Conserved SCN9A Natural Antisense Transcript Expressed in Dorsal Root Ganglia.

    Directory of Open Access Journals (Sweden)

    Jennifer Koenig

    Full Text Available The Nav1.7 voltage-gated sodium channel, encoded by SCN9A, is critical for human pain perception yet the transcriptional and post-transcriptional mechanisms that regulate this gene are still incompletely understood. Here, we describe a novel natural antisense transcript (NAT for SCN9A that is conserved in humans and mice. The NAT has a similar tissue expression pattern to the sense gene and is alternatively spliced within dorsal root ganglia. The human and mouse NATs exist in cis with the sense gene in a tail-to-tail orientation and both share sequences that are complementary to the terminal exon of SCN9A/Scn9a. Overexpression analyses of the human NAT in human embryonic kidney (HEK293A and human neuroblastoma (SH-SY5Y cell lines show that it can function to downregulate Nav1.7 mRNA, protein levels and currents. The NAT may play an important role in regulating human pain thresholds and is a potential candidate gene for individuals with chronic pain disorders that map to the SCN9A locus, such as Inherited Primary Erythromelalgia, Paroxysmal Extreme Pain Disorder and Painful Small Fibre Neuropathy, but who do not contain mutations in the sense gene. Our results strongly suggest the SCN9A NAT as a prime candidate for new therapies based upon augmentation of existing antisense RNAs in the treatment of chronic pain conditions in man.

  16. Regulation of Nav1.7: A Conserved SCN9A Natural Antisense Transcript Expressed in Dorsal Root Ganglia.

    Science.gov (United States)

    Koenig, Jennifer; Werdehausen, Robert; Linley, John E; Habib, Abdella M; Vernon, Jeffrey; Lolignier, Stephane; Eijkelkamp, Niels; Zhao, Jing; Okorokov, Andrei L; Woods, C Geoffrey; Wood, John N; Cox, James J

    2015-01-01

    The Nav1.7 voltage-gated sodium channel, encoded by SCN9A, is critical for human pain perception yet the transcriptional and post-transcriptional mechanisms that regulate this gene are still incompletely understood. Here, we describe a novel natural antisense transcript (NAT) for SCN9A that is conserved in humans and mice. The NAT has a similar tissue expression pattern to the sense gene and is alternatively spliced within dorsal root ganglia. The human and mouse NATs exist in cis with the sense gene in a tail-to-tail orientation and both share sequences that are complementary to the terminal exon of SCN9A/Scn9a. Overexpression analyses of the human NAT in human embryonic kidney (HEK293A) and human neuroblastoma (SH-SY5Y) cell lines show that it can function to downregulate Nav1.7 mRNA, protein levels and currents. The NAT may play an important role in regulating human pain thresholds and is a potential candidate gene for individuals with chronic pain disorders that map to the SCN9A locus, such as Inherited Primary Erythromelalgia, Paroxysmal Extreme Pain Disorder and Painful Small Fibre Neuropathy, but who do not contain mutations in the sense gene. Our results strongly suggest the SCN9A NAT as a prime candidate for new therapies based upon augmentation of existing antisense RNAs in the treatment of chronic pain conditions in man.

  17. Phytochemistry of cimicifugic acids and associated bases in Cimicifuga racemosa root extracts.

    Science.gov (United States)

    Gödecke, Tanja; Nikolic, Dejan; Lankin, David C; Chen, Shao-Nong; Powell, Sharla L; Dietz, Birgit; Bolton, Judy L; van Breemen, Richard B; Farnsworth, Norman R; Pauli, Guido F

    2009-01-01

    Earlier studies reported serotonergic activity for cimicifugic acids (CA) isolated from Cimicifuga racemosa. The discovery of strongly basic alkaloids, cimipronidines, from the active extract partition and evaluation of previously employed work-up procedures has led to the hypothesis of strong acid/base association in the extract. Re-isolation of the CAs was desired to permit further detailed studies. Based on the acid/base association hypothesis, a new separation scheme of the active partition was required, which separates acids from associated bases. A new 5-HT(7) bioassay guided work-up procedure was developed that concentrates activity into one partition. The latter was subjected to a new two-step centrifugal partitioning chromatography (CPC) method, which applies pH zone refinement gradient (pHZR CPC) to dissociate the acid/base complexes. The resulting CA fraction was subjected to a second CPC step. Fractions and compounds were monitored by (1)H NMR using a structure-based spin-pattern analysis facilitating dereplication of the known acids. Bioassay results were obtained for the pHZR CPC fractions and for purified CAs. A new CA was characterised. While none of the pure CAs was active, the serotonergic activity was concentrated in a single pHZR CPC fraction, which was subsequently shown to contain low levels of the potent 5-HT(7) ligand, N(omega)-methylserotonin. This study shows that CAs are not responsible for serotonergic activity in black cohosh. New phytochemical methodology (pHZR CPC) and a sensitive dereplication method (LC-MS) led to the identification of N(omega)-methylserotonin as serotonergic active principle. Copyright (c) 2009 John Wiley & Sons, Ltd.

  18. Nitric Oxide Contributes to Cadmium Toxicity in Arabidopsis by Promoting Cadmium Accumulation in Roots and by Up-Regulating Genes Related to Iron Uptake1[W

    Science.gov (United States)

    Besson-Bard, Angélique; Gravot, Antoine; Richaud, Pierre; Auroy, Pascaline; Duc, Céline; Gaymard, Frédéric; Taconnat, Ludivine; Renou, Jean-Pierre; Pugin, Alain; Wendehenne, David

    2009-01-01

    Nitric oxide (NO) functions as a cell-signaling molecule in plants. In particular, a role for NO in the regulation of iron homeostasis and in the plant response to toxic metals has been proposed. Here, we investigated the synthesis and the role of NO in plants exposed to cadmium (Cd2+), a nonessential and toxic metal. We demonstrate that Cd2+ induces NO synthesis in roots and leaves of Arabidopsis (Arabidopsis thaliana) seedlings. This production, which is sensitive to NO synthase inhibitors, does not involve nitrate reductase and AtNOA1 but requires IRT1, encoding a major plasma membrane transporter for iron but also Cd2+. By analyzing the incidence of NO scavenging or inhibition of its synthesis during Cd2+ treatment, we demonstrated that NO contributes to Cd2+-triggered inhibition of root growth. To understand the mechanisms underlying this process, a microarray analysis was performed in order to identify NO-modulated root genes up- and down-regulated during Cd2+ treatment. Forty-three genes were identified encoding proteins related to iron homeostasis, proteolysis, nitrogen assimilation/metabolism, and root growth. These genes include IRT1. Investigation of the metal and ion contents in Cd2+-treated roots in which NO synthesis was impaired indicates that IRT1 up-regulation by NO was consistently correlated to NO's ability to promote Cd2+ accumulation in roots. This analysis also highlights that NO is responsible for Cd2+-induced inhibition of root Ca2+ accumulation. Taken together, our results suggest that NO contributes to Cd2+ toxicity by favoring Cd2+ versus Ca2+ uptake and by initiating a cellular pathway resembling those activated upon iron deprivation. PMID:19168643

  19. Nitric oxide contributes to cadmium toxicity in Arabidopsis by promoting cadmium accumulation in roots and by up-regulating genes related to iron uptake.

    Science.gov (United States)

    Besson-Bard, Angélique; Gravot, Antoine; Richaud, Pierre; Auroy, Pascaline; Duc, Céline; Gaymard, Frédéric; Taconnat, Ludivine; Renou, Jean-Pierre; Pugin, Alain; Wendehenne, David

    2009-03-01

    Nitric oxide (NO) functions as a cell-signaling molecule in plants. In particular, a role for NO in the regulation of iron homeostasis and in the plant response to toxic metals has been proposed. Here, we investigated the synthesis and the role of NO in plants exposed to cadmium (Cd(2+)), a nonessential and toxic metal. We demonstrate that Cd(2+) induces NO synthesis in roots and leaves of Arabidopsis (Arabidopsis thaliana) seedlings. This production, which is sensitive to NO synthase inhibitors, does not involve nitrate reductase and AtNOA1 but requires IRT1, encoding a major plasma membrane transporter for iron but also Cd(2+). By analyzing the incidence of NO scavenging or inhibition of its synthesis during Cd(2+) treatment, we demonstrated that NO contributes to Cd(2+)-triggered inhibition of root growth. To understand the mechanisms underlying this process, a microarray analysis was performed in order to identify NO-modulated root genes up- and down-regulated during Cd(2+) treatment. Forty-three genes were identified encoding proteins related to iron homeostasis, proteolysis, nitrogen assimilation/metabolism, and root growth. These genes include IRT1. Investigation of the metal and ion contents in Cd(2+)-treated roots in which NO synthesis was impaired indicates that IRT1 up-regulation by NO was consistently correlated to NO's ability to promote Cd(2+) accumulation in roots. This analysis also highlights that NO is responsible for Cd(2+)-induced inhibition of root Ca(2+) accumulation. Taken together, our results suggest that NO contributes to Cd(2+) toxicity by favoring Cd(2+) versus Ca(2+) uptake and by initiating a cellular pathway resembling those activated upon iron deprivation.

  20. Arabidopsis phosphatidylinositol monophosphate 5-kinase 2 is involved in root gravitropism through regulation of polar auxin transport by affecting the cycling of PIN proteins

    Institute of Scientific and Technical Information of China (English)

    Yu Mei; Wen-Jing Jia; Yu-Jia Chu; Hong-Wei Xue

    2012-01-01

    Phosphatidylinositol monophosphate 5-kinase(PIP5K)catalyzes the synthesis of PI-4,5-bisphosphate(PtdIns(4,5)P2)by phosphorylation of PI-4-phosphate at the 5 position of the inositol ring,and is involved in regulating multiple developmental processes and stress responses.We here report on the functional characterization of Arabidopsis PIP5K2,which is expressed during lateral root initiation and elongation,and whose expression is enhanced by exogenous auxin.The knockout mutant pip5k2 shows reduced lateral root formation,which could be recovered with exogenous auxin,and interestingly,delayed root gravity response that could not be recovered with exogenous auxin.Crossing with the DR5-GUS marker line and measurement of free IAA content confirmed the reduced auxin accumulation in pip5k2.In addition,analysis using the membrane-selective dye FM4-64 revealed the decelerated vesicle trafficking caused by PtdIns(4,5)P2 reduction,which hence results in suppressed cycling of PIN proteins(PIN2 and 3),and delayed redistribution of PIN2 and auxin under gravistimulation in pipSk2 roots.On the contrary,PtdIns(4,5)P2 significantly enhanced the vesicle trafficking and cycling of PIN proteins.These results demonstrate that PIP5K2 is involved in regulating lateral root formation and root gravity response,and reveal a critical role of PIP5K2/Ptdlns(4,5)P2 in root development through regulation of PIN proteins,providing direct evidence of crosstalk between the phosphatidylinositol signaling pathway and auxin response,and new insights into the control of polar auxin transport.

  1. Postharvest salicylic acid treatment reduces storage rots in water-stressed but no unstressed sugarbeet roots

    Science.gov (United States)

    Exogenous application of salicylic acid (SA) reduces storage rots in a number of postharvest crops. SA’s ability to protect sugarbeet (Beta vulgaris L.) taproots from common storage rot pathogens, however, is unknown. To determine the potential of SA to reduce storage losses caused by three common...

  2. Sialic acid accelerates the electrophoretic velocity of injured dorsal root ganglion neurons

    Directory of Open Access Journals (Sweden)

    Chen-xu Li

    2015-01-01

    Full Text Available Peripheral nerve injury has been shown to result in ectopic spontaneous discharges on soma and injured sites of sensory neurons, thereby inducing neuropathic pain. With the increase of membrane proteins on soma and injured site neurons, the negatively charged sialic acids bind to the external domains of membrane proteins, resulting in an increase of this charge. We therefore speculate that the electrophoretic velocity of injured neurons may be faster than non-injured neurons. The present study established rat models of neuropathic pain via chronic constriction injury. Results of the cell electrophoresis test revealed that the electrophoretic velocity of injured neuronal cells was faster than that of non-injured (control cells. We then treated cells with divalent cations of Ca 2+ and organic compounds with positive charges, polylysine to counteract the negatively charged sialic acids, or neuraminidase to specifically remove sialic acids from the membrane surface of injured neurons. All three treatments significantly reduced the electrophoretic velocity of injured neuronal cells. These findings suggest that enhanced sialic acids on injured neurons may accelerate the electrophoretic velocity of injured neurons.

  3. Sialic acid accelerates the electrophoretic velocity of injured dorsal root ganglion neurons

    Institute of Scientific and Technical Information of China (English)

    Chen-xu Li; Guo-ying Ma; Min-fang Guo; Ying Liu

    2015-01-01

    Peripheral nerve injury has been shown to result in ectopic spontaneous discharges on soma and injured sites of sensory neurons, thereby inducing neuropathic pain. With the increase of membrane proteins on soma and injured site neurons, the negatively charged sialic acids bind to the external domains of membrane proteins, resulting in an increase of this charge. We therefore speculate that the electrophoretic velocity of injured neurons may be faster than non-injured neurons. The present study established rat models of neuropathic pain via chronic constriction injury. Results of the cell electrophoresis test revealed that the electrophoretic velocity of injured neuronal cells was faster than that of non-injured (control) cells. We then treated cells with di-valent cations of Ca2+and organic compounds with positive charges, polylysine to counteract the negatively charged sialic acids, or neuraminidase to speciifcally remove sialic acids from the membrane surface of injured neurons. All three treatments significantly reduced the electro-phoretic velocity of injured neuronal cells. These ifndings suggest that enhanced sialic acids on injured neurons may accelerate the electrophoretic velocity of injured neurons.

  4. Physiological responses of root-less epiphytic plants to acid rain.

    Science.gov (United States)

    Kováčik, Jozef; Klejdus, Bořivoj; Bačkor, Martin; Stork, František; Hedbavny, Josef

    2011-03-01

    Selected physiological responses of Tillandsia albida (Bromeliaceae) and two lichens (Hypogymnia physodes and Xanthoria parietina) exposed to simulated acid rain (AR) over 3 months were studied. Pigments were depressed in all species being affected the most in Tillandsia. Amounts of hydrogen peroxide and superoxide were elevated and soluble proteins decreased only in AR-exposed Hypogymnia. Free amino acids were slightly affected among species and only glutamate sharply decreased in AR-exposed Xanthoria. Slight increase in soluble phenols but decrease in flavonoids in almost all species suggests that the latter are not essential for tolerance to AR. Almost all phenolic acids in Tillandsia leaves decreased in response to AR and activities of selected enzymes (phenylalanine ammonia-lyase, polyphenol oxidase, ascorbate- and guaiacol-peroxidase) were enhanced by AR. In lichens, considerable increase in metabolites (physodalic acid, atranorin and parietin) in response to AR was found but amount of ergosterol was unchanged. Macronutrients (K, Ca, Mg) decreased more pronouncedly in comparison with micronutrients in all species. Xanthoria showed higher tolerance in comparison with Hypogymnia, suggesting that could be useful for long-term biomonitoring.

  5. Influence of season and salinity on the exudation of aliphatic low molecular weight organic acids (ALMWOAs) by Phragmites australis and Halimione portulacoides roots

    Science.gov (United States)

    Rocha, A. Cristina S.; Almeida, C. Marisa R.; Basto, M. Clara P.; Vasconcelos, M. Teresa S. D.

    2015-01-01

    Plant roots have the ability to produce and secrete substances, such as aliphatic low molecular weight organic acids (ALMWOAs), into the rhizosphere. This phenomenon occurs for several purposes, for instance, the detoxification of pollutants. Nevertheless, knowledge about the exudation of such substances from marsh plants roots is still scarce. This work aimed at studying: 1) the ability of marsh plants, freshly collected in estuarine marshes, to liberate ALMWOAs into the surrounding medium and 2) the influence of the physiological cycle of these plants on the exudation of those substances. In vitro experiments were carried out, in different seasons, with Phragmites australis and Halimione portulacoides (two marsh plants widely distributed in Europe). Root exudates were collected in freshwater to which plant specimens, in different physiological stages, were exposed. Both marsh plants were capable of liberating oxalic and citric acids into the surrounding medium. Formic acid was also released by P. australis roots and acetic acid by H. portulacoides. There was a seasonal effect on the liberation of ALMWOAs by both plant roots. Marked changes were registered in the nature and levels of the ALMWOAs liberated and such changes depended upon the season in which the specimens were collected. In growing season, a significantly higher liberation of oxalic and citric acids (and acetic acid but only in H. portulacoides case) was observed. For P. australis, formic acid was only found in the decaying stage (autumn and winter). The nature of the medium (in particular, salinity) was a feature conditioning the exudation of ALMWOAs. Both plants were shown to contribute for the presence of ALMWOAs in marsh rhizosediments (some ALMWOAs were found in pore waters extracted). The nature and extent of this contribution will be however dependent upon plants' physiological stage, in addition to plant species. Therefore, these features should be taken into consideration in the event of

  6. Lotus tenuis tolerates combined salinity and waterlogging: maintaining O2 transport to roots and expression of an NHX1-like gene contribute to regulation of Na+ transport.

    Science.gov (United States)

    Teakle, Natasha L; Amtmann, Anna; Real, Daniel; Colmer, Timothy D

    2010-08-01

    Salinity and waterlogging interact to reduce growth for most crop and pasture species. The combination of these stresses often cause a large increase in the rate of Na(+) and Cl(-) transport to shoots; however, the mechanisms responsible for this are largely unknown. To identify mechanisms contributing to the adverse interaction between salinity and waterlogging, we compared two Lotus species with contrasting tolerances when grown under saline (200 mM NaCl) and O(2)-deficient (stagnant) treatments. Measurements of radial O(2) loss (ROL) under stagnant conditions indicated that more O(2) reaches root tips of Lotus tenuis, compared with Lotus corniculatus. Better internal aeration would contribute to maintaining Na(+) and Cl(-) transport processes in roots of L. tenuis exposed to stagnant-plus-NaCl treatments. L. tenuis root Na(+) concentrations after stagnant-plus-NaCl treatment (200 mM) were 17% higher than L. corniculatus, with 55% of the total plant Na(+) being accumulated in roots, compared with only 39% for L. corniculatus. L. tenuis accumulated more Na(+) in roots, presumably in vacuoles, thereby reducing transport to the shoot (25% lower than L. corniculatus). A candidate gene for vacuole Na(+) accumulation, an NHX1-like gene, was cloned from L. tenuis and identity established via sequencing and yeast complementation. Transcript levels of NHX1 in L. tenuis roots under stagnant-plus-NaCl treatment were the same as for aerated NaCl, whereas L. corniculatus roots had reduced transcript levels. Enhanced O(2) transport to roots enables regulation of Na(+) transport processes in L. tenuis roots, contributing to tolerance to combined salinity and waterlogging stresses.

  7. EFFECTS OF PLANT GROWTH REGULATORS ON SHOOT MULTIPLICATION AND ROOT INDUCTION OF CASSAVA VARIETIES CULTURE IN VITRO

    Directory of Open Access Journals (Sweden)

    HERNI WIDHIASTUTI

    2011-01-01

    Full Text Available A study on propagation of three superior cassava ( Crant varieties i.e.Darul Hidayah, Malang-6 and Adira-4 through tissue culture technique was conducted at theTissue Culture Lab of SEAMEO BIOTROP, Bogor. The objective of the experiment was tostudy effect of plant growth regulators on propagation, which can be used in cassavamicropropagation protocol. Plant materials used were auxiliary shoots of a stem node. Theexperiment consisted of (i shoot multiplication, (ii roots induction, and (iii acclimatization.The multiple shoot regeneration was observed by using Murashige & Skoog (MS basal mediasupplemented with 0, 0.1, 1.0 and 5.0 mg/L of benzylaminopurine (BAP combined with 0.0,0.1 and 1.0 mg/L of thidiazuron. The root induction was observed by using 0.1 and 1.0 mg/Lof IBA and NAA. The resulting plantlets were transplanted into plastic polybags containingsoil mixed with organic fertilizer (1:1 covered with plastic sheets and transferred to agreenhouse. The result of the study showed that the highest number of shoots for DarulHidayah, Malang-6 and Adira-4 varieties were 4.93 shoots treated with BAP 1 mg/L +thidiazuron 0.1 mg/L, 4.20 shoots at BAP media of 1 mg/L, and 7.20 shoots at the mediaof BAP 1 mg/L + thidiazuron 0.1 mg/L respectively. The highest number of nodes producedwas 2.9 nodes for Darul Hidayah at BAP 5 mg/L, 5.13 nodes for Malang-6 at BAP 0.1 mg/L,and 6.18 nodes for Adira-4 at BAP 5 mg/L + thidiazuron 1 mg/L. The utilization of auxin IAAor NAA could induce and accelerate the growth of roots which finally could increase thesuccess of acclimatization process. With an average of four multiplication factors of eachculture period, the potency of each cassava shoot propagated through tissue culture couldproduce around 37 000 plants/year.

  8. Root cap-dependent gravitropic U-turn of maize root requires light-induced auxin biosynthesis via the YUC pathway in the root apex

    Science.gov (United States)

    Suzuki, Hiromi; Yokawa, Ken; Nakano, Sayuri; Yoshida, Yuriko; Fabrissin, Isabelle; Okamoto, Takashi; Baluška, František; Koshiba, Tomokazu

    2016-01-01

    Gravitropism refers to the growth or movement of plants that is influenced by gravity. Roots exhibit positive gravitropism, and the root cap is thought to be the gravity-sensing site. In some plants, the root cap requires light irradiation for positive gravitropic responses. However, the mechanisms regulating this phenomenon are unknown. We herein report that maize roots exposed to white light continuously for ≥1–2h show increased indole-3-acetic acid (IAA) levels in the root tips, especially in the transition zone (1–3mm from the tip). Treatment with IAA biosynthesis inhibitors yucasin and l-kynurenine prevented any increases in IAA content and root curvature under light conditions. Analyses of the incorporation of a stable isotope label from tryptophan into IAA revealed that some of the IAA in roots was synthesized in the root apex. Furthermore, Zmvt2 and Zmyuc gene transcripts were detected in the root apex. One of the Zmyuc genes (ZM2G141383) was up-regulated by light irradiation in the 0–1mm tip region. Our findings suggest that IAA accumulation in the transition zone is due to light-induced activation of Zmyuc gene expression in the 0–1mm root apex region. Light-induced changes in IAA levels and distributions mediate the maize root gravitropic U-turn. PMID:27307546

  9. Xenobiotic, bile acid, and cholesterol transporters: function and regulation.

    Science.gov (United States)

    Klaassen, Curtis D; Aleksunes, Lauren M

    2010-03-01

    Transporters influence the disposition of chemicals within the body by participating in absorption, distribution, and elimination. Transporters of the solute carrier family (SLC) comprise a variety of proteins, including organic cation transporters (OCT) 1 to 3, organic cation/carnitine transporters (OCTN) 1 to 3, organic anion transporters (OAT) 1 to 7, various organic anion transporting polypeptide isoforms, sodium taurocholate cotransporting polypeptide, apical sodium-dependent bile acid transporter, peptide transporters (PEPT) 1 and 2, concentrative nucleoside transporters (CNT) 1 to 3, equilibrative nucleoside transporter (ENT) 1 to 3, and multidrug and toxin extrusion transporters (MATE) 1 and 2, which mediate the uptake (except MATEs) of organic anions and cations as well as peptides and nucleosides. Efflux transporters of the ATP-binding cassette superfamily, such as ATP-binding cassette transporter A1 (ABCA1), multidrug resistance proteins (MDR) 1 and 2, bile salt export pump, multidrug resistance-associated proteins (MRP) 1 to 9, breast cancer resistance protein, and ATP-binding cassette subfamily G members 5 and 8, are responsible for the unidirectional export of endogenous and exogenous substances. Other efflux transporters [ATPase copper-transporting beta polypeptide (ATP7B) and ATPase class I type 8B member 1 (ATP8B1) as well as organic solute transporters (OST) alpha and beta] also play major roles in the transport of some endogenous chemicals across biological membranes. This review article provides a comprehensive overview of these transporters (both rodent and human) with regard to tissue distribution, subcellular localization, and substrate preferences. Because uptake and efflux transporters are expressed in multiple cell types, the roles of transporters in a variety of tissues, including the liver, kidneys, intestine, brain, heart, placenta, mammary glands, immune cells, and testes are discussed. Attention is also placed upon a variety of

  10. The effect of laterally positioned flap-revised technique and 24% ethylenediaminetetraacetic acid root conditioning on root coverage: A case report.

    Science.gov (United States)

    Singh, Jagmohan; Bharti, Vipin

    2014-07-01

    Complete root coverage is considered the true goal of treatment of gingival recession defects because only complete coverage assures recovery from the hypersensitivity and esthetic defects associated with recession areas. Previous studies have shown that the laterally positioned flap (LPF) technique or root surface biomodification yields a higher percentage of complete root coverage upon gingival