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Sample records for aba signaling genes

  1. A Putative PP2C-Encoding Gene Negatively Regulates ABA Signaling in Populus euphratica.

    PubMed

    Chen, Jinhuan; Zhang, Dongzhi; Zhang, Chong; Xia, Xinli; Yin, Weilun; Tian, Qianqian

    2015-01-01

    A PP2C homolog gene was cloned from the drought-treated cDNA library of Populus euphratica. Multiple sequence alignment analysis suggested that the gene is a potential ortholog of HAB1. The expression of this HAB1 ortholog (PeHAB1) was markedly induced by drought and moderately induced by ABA. To characterize its function in ABA signaling, we generated transgenic Arabidopsis thaliana plants overexpressing this gene. Transgenic lines exhibited reduced responses to exogenous ABA and reduced tolerance to drought compared to wide-type lines. Yeast two-hybrid analyses indicated that PeHAB1 could interact with the ABA receptor PYL4 in an ABA-independent manner. Taken together; these results indicated that PeHAB1 is a new negative regulator of ABA responses in poplar.

  2. Sulphate as a xylem-borne chemical signal precedes the expression of ABA biosynthetic genes in maize roots.

    PubMed

    Ernst, Laura; Goodger, Jason Q D; Alvarez, Sophie; Marsh, Ellen L; Berla, Bert; Lockhart, Eric; Jung, Jiyul; Li, Pinghua; Bohnert, Hans J; Schachtman, Daniel P

    2010-07-01

    Recent reports suggest that early sensing of soil water stress by plant roots and the concomitant reduction in stomatal conductance may not be mediated by root-sourced abscisic acid (ABA), but that other xylem-borne chemicals may be the primary stress signal(s). To gain more insight into the role of root-sourced ABA, the timing and location of the expression of genes for key enzymes involved in ABA biosynthesis in Zea mays roots was measured and a comprehensive analysis of root xylem sap constituents from the early to the later stages of water stress was conducted. Xylem sap and roots were sampled from plants at an early stage of water stress when only a reduction in leaf conductance was measured, as well as at later stages when leaf xylem pressure potential decreased. It was found that the majority of ABA biosynthetic genes examined were only significantly expressed in the elongation region of roots at a later stage of water stress. Apart from ABA, sulphate was the only xylem-borne chemical that consistently showed significantly higher concentrations from the early to the later stages of stress. Moreover, there was an interactive effect of ABA and sulphate in decreasing maize transpiration rate and Vicia faba stomatal aperture, as compared to ABA alone. The expression of a sulphate transporter gene was also analysed and it was found that it had increased in the elongation region of roots from the early to the later stages of water stress. Our results support the suggestion that in the early stage of water stress, increased levels of ABA in xylem sap may not be due to root biosynthesis, ABA glucose ester catabolism or pH-mediated redistribution, but may be due to shoot biosynthesis and translocation to the roots. The analysis of xylem sap mineral content and bioassays indicate that the anti-transpirant effect of the ABA reaching the stomata at the early stages of water stress may be enhanced by the increased concentrations of sulphate in the xylem which is also

  3. BnSIP1-1, a Trihelix Family Gene, Mediates Abiotic Stress Tolerance and ABA Signaling in Brassica napus

    PubMed Central

    Luo, Junling; Tang, Shaohua; Mei, Fengling; Peng, Xiaojue; Li, Jun; Li, Xiaofei; Yan, Xiaohong; Zeng, Xinhua; Liu, Fang; Wu, Yuhua; Wu, Gang

    2017-01-01

    The trihelix family genes have important functions in light-relevant and other developmental processes, but their roles in response to adverse environment are largely unclear. In this study, we identified a new gene, BnSIP1-1, which fell in the SIP1 (6b INTERACTING PROTEIN1) clade of the trihelix family with two trihelix DNA binding domains and a fourth amphipathic α-helix. BnSIP1-1 protein specifically targeted to the nucleus, and its expression can be induced by abscisic acid (ABA) and different stresses. Overexpression of BnSIP1-1 improved seed germination under osmotic pressure, salt, and ABA treatments. Moreover, BnSIP1-1 decreased the susceptibility of transgenic seedlings to osmotic pressure and ABA treatments, whereas there was no difference under salt stress between the transgenic and wild-type seedlings. ABA level in the transgenic seedlings leaves was higher than those in the control plants under normal condition. Under exogenous ABA treatment and mannitol stress, the accumulation of ABA in the transgenic plants was higher than that in the control plants; while under salt stress, the difference of ABA content before treatment was gradually smaller with the prolongation of salt treatment time, then after 24 h of treatment the ABA level was similar in transgenic and wild-type plants. The transcription levels of several general stress marker genes (BnRD29A, BnERD15, and BnLEA1) were higher in the transgenic plants than the wild-type plants, whereas salt-responsive genes (BnSOS1, BnNHX1, and BnHKT) were not significantly different or even reduced compared with the wild-type plants, which indicated that BnSIP1-1 specifically exerted different regulatory mechanisms on the osmotic- and salt-response pathways in seedling period. Overall, these findings suggested that BnSIP1-1 played roles in ABA synthesis and signaling, salt and osmotic stress response. To date, information about the involvement of the Brassica napus trihelix gene in abiotic response is scarce

  4. Evolutionary Conservation of ABA Signaling for Stomatal Closure in Ferns.

    PubMed

    Cai, Shengguan; Chen, Guang; Wang, Yuanyuan; Huang, Yuqing; Marchant, Blaine; Wang, Yizhou; Yang, Qian; Dai, Fei; Hills, Adrian; Franks, Peter J; Nevo, Eviatar; Soltis, Doug; Soltis, Pamela; Sessa, Emily; Wolf, Paul G; Xue, Dawei; Zhang, Guoping; Pogson, Barry J; Blatt, Mike R; Chen, Zhong-Hua

    2017-02-23

    ABA-driven stomatal regulation reportedly evolved after the divergence of ferns, during the early evolution of seed plants approximately 360 Mya. This hypothesis is based on the observation that the stomata of certain fern species are unresponsive to ABA, but exhibit passive hydraulic control. However, ABA-induced stomatal closure was detected in some mosses and lycophytes. Here, we observed that a number of ABA signaling and membrane transporter protein families diversified over the evolutionary history of land plants. The aquatic ferns Azolla filiculoides and Salvinia cucullata have representatives of 23 families of proteins orthologous to those of Arabidopsis thaliana and all other land plant species studied. Phylogenetic analysis of the key ABA signaling proteins indicates an evolutionarily conserved stomatal response to ABA. Moreover, comparative transcriptomic analysis has identified a suite of ABA responsive genes that differentially expressed in a terrestrial fern species, Polystichum proliferum. These genes encode proteins associated with ABA biosynthesis, transport, reception, transcription, signaling, and ion and sugar transport, which fit the general ABA signaling pathway constructed from Arabidopsis thaliana and Hordeum vulgare. The retention of these key ABA-responsive genes could have had a profound effect on the adaptation of ferns to dry conditions. Furthermore, stomatal assays have shown the primary evidence for ABA-induced closure of stomata in two terrestrial fern species P. proliferum and Nephrolepis exaltata. In summary, we report new molecular and physiological evidence for the presence of active stomatal control in ferns.

  5. The rose (Rosa hybrida) NAC transcription factor 3 gene, RhNAC3, involved in ABA signaling pathway both in rose and Arabidopsis.

    PubMed

    Jiang, Guimei; Jiang, Xinqiang; Lü, Peitao; Liu, Jitao; Gao, Junping; Zhang, Changqing

    2014-01-01

    Plant transcription factors involved in stress responses are generally classified by their involvement in either the abscisic acid (ABA)-dependent or the ABA-independent regulatory pathways. A stress-associated NAC gene from rose (Rosa hybrida), RhNAC3, was previously found to increase dehydration tolerance in both rose and Arabidopsis. However, the regulatory mechanism involved in RhNAC3 action is still not fully understood. In this study, we isolated and analyzed the upstream regulatory sequence of RhNAC3 and found many stress-related cis-elements to be present in the promoter, with five ABA-responsive element (ABRE) motifs being of particular interest. Characterization of Arabidopsis thaliana plants transformed with the putative RhNAC3 promoter sequence fused to the β-glucuronidase (GUS) reporter gene revealed that RhNAC3 is expressed at high basal levels in leaf guard cells and in vascular tissues. Moreover, the ABRE motifs in the RhNAC3 promoter were observed to have a cumulative effect on the transcriptional activity of this gene both in the presence and absence of exogenous ABA. Overexpression of RhNAC3 in A. thaliana resulted in ABA hypersensitivity during seed germination and promoted leaf closure after ABA or drought treatments. Additionally, the expression of 11 ABA-responsive genes was induced to a greater degree by dehydration in the transgenic plants overexpressing RhNAC3 than control lines transformed with the vector alone. Further analysis revealed that all these genes contain NAC binding cis-elements in their promoter regions, and RhNAC3 was found to partially bind to these putative NAC recognition sites. We further found that of 219 A. thaliana genes previously shown by microarray analysis to be regulated by heterologous overexpression RhNAC3, 85 are responsive to ABA. In rose, the expression of genes downstream of the ABA-signaling pathways was also repressed in RhNAC3-silenced petals. Taken together, we propose that the rose RhNAC3 protein

  6. Characterization of the ABA signal transduction pathway in Vitis vinifera.

    PubMed

    Boneh, Uri; Biton, Iris; Schwartz, Amnon; Ben-Ari, Giora

    2012-05-01

    The plant hormone abscisic acid (ABA) regulates many key processes in plants including the response to abiotic stress. ABA signal transduction consists of a double-negative regulatory mechanism, whereby ABA-bound PYR/RCARs inhibit PP2C activity, and PP2Cs inactivate SnRK2s. We studied and analyzed the various genes participating in the ABA signaling cascade of the grape (Vitis vinifera). The grape ABA signal transduction consists of at least six SnRK2s. Yeast two-hybrid system was used to test direct interactions between core components of grape ABA signal transduction. We found that a total of forty eight interactions can occur between the various components. Exogenous abscisic acid (ABA) and abiotic stresses such as drought, high salt concentration and cold, were applied to vines growing in a hydroponic system. These stresses regulated the expression of various grape SnRK2s as well as ABFs in leaves and roots. Based on the interactions between SnRK2s and its targets and the expression pattern, we suggest that VvSnRK2.1 and VvSnRK2.6, can be considered the major VvSnRK2 candidates involved in the stomata response to abiotic stress. Furthermore, we found that the expression pattern of the two grape ABF genes indicates organ specificity of these genes. The key role of ABA signaling in response to abiotic stresses makes the genes involve in this signaling potential candidates for manipulation in programs designed to improve fruit tree performance in extreme environments.

  7. Molecular cloning and characterization of the ABA-specific glucosyltransferase gene from bean (Phaseolus vulgaris L.).

    PubMed

    Palaniyandi, Sasikumar Arunachalam; Chung, Gyuhwa; Kim, Sang Hyon; Yang, Seung Hwan

    2015-04-15

    Levels of the plant hormone abscisic acid (ABA) are maintained in homeostasis by a balance of its biosynthesis, catabolism and conjugation. The detailed molecular and signaling events leading to strict homeostasis are not completely understood in crop plants. In this study, we obtained cDNA of an ABA-inducible, ABA-specific UDP-glucosyltransferase (ABAGT) from the bean plant (Phaseolus vulgaris L.) involved in conjugation of a glucose residue to ABA to form inactive ABA-glucose ester (ABA-GE) to examine its role during development and abiotic stress in bean. The bacterially expressed PvABAGTase enzyme showed ABA-specific glucosylation activity in vitro. A higher level of the PvABAGT transcript was observed in mature leaves, mature flowers, roots, seed coats and embryos as well as upon rehydration following a period of dehydration. Overexpression of 35S::PvABAGT in Arabidopsis showed reduced sensitivity to ABA compared with WT. The transgenic plants showed a high level of ABA-GE without significant decrease in the level of ABA compared with the wild type (WT) during dehydration stress. Upon rehydration, the levels of ABA and phaseic acid (PA) decreased in the WT and the PvABAGT-overexpressing lines with high levels of ABA-GE only in the transgenic plants. Our findings suggest that the PvABAGT gene could play a role in ABA homeostasis during development and stress responses in bean and its overexpression in Arabidopsis did not alter ABA homeostasis during dehydration stress.

  8. Comprehensive Analysis of ABA Effects on Ethylene Biosynthesis and Signaling during Tomato Fruit Ripening

    PubMed Central

    Bu, Jianwen; Jiang, Yuanyuan; Khan, Zia Ullah; Luo, Zisheng; Mao, Linchun; Ying, Tiejin

    2016-01-01

    ABA has been widely acknowledged to regulate ethylene biosynthesis and signaling during fruit ripening, but the molecular mechanism underlying the interaction between these two hormones are largely unexplored. In the present study, exogenous ABA treatment obviously promoted fruit ripening as well as ethylene emission, whereas NDGA (Nordihydroguaiaretic acid, an inhibitor of ABA biosynthesis) application showed the opposite biological effects. Combined RNA-seq with time-course RT-PCR analysis, our study not only helped to illustrate how ABA regulated itself at the transcription level, but also revealed that ABA can facilitate ethylene production and response probably by regulating some crucial genes such as LeACS4, LeACO1, GR and LeETR6. In addition, investigation on the fruits treated with 1-MCP immediately after ABA exposure revealed that ethylene might be essential for the induction of ABA biosynthesis and signaling at the onset of fruit ripening. Furthermore, some specific transcription factors (TFs) known as regulators of ethylene synthesis and sensibility (e.g. MADS-RIN, TAGL1, CNR and NOR) were also observed to be ABA responsive, which implied that ABA influenced ethylene action possibly through the regulation of these TFs expression. Our comprehensive physiological and molecular-level analysis shed light on the mechanism of cross-talk between ABA and ethylene during the process of tomato fruit ripening. PMID:27100326

  9. Comprehensive Analysis of ABA Effects on Ethylene Biosynthesis and Signaling during Tomato Fruit Ripening.

    PubMed

    Mou, Wangshu; Li, Dongdong; Bu, Jianwen; Jiang, Yuanyuan; Khan, Zia Ullah; Luo, Zisheng; Mao, Linchun; Ying, Tiejin

    2016-01-01

    ABA has been widely acknowledged to regulate ethylene biosynthesis and signaling during fruit ripening, but the molecular mechanism underlying the interaction between these two hormones are largely unexplored. In the present study, exogenous ABA treatment obviously promoted fruit ripening as well as ethylene emission, whereas NDGA (Nordihydroguaiaretic acid, an inhibitor of ABA biosynthesis) application showed the opposite biological effects. Combined RNA-seq with time-course RT-PCR analysis, our study not only helped to illustrate how ABA regulated itself at the transcription level, but also revealed that ABA can facilitate ethylene production and response probably by regulating some crucial genes such as LeACS4, LeACO1, GR and LeETR6. In addition, investigation on the fruits treated with 1-MCP immediately after ABA exposure revealed that ethylene might be essential for the induction of ABA biosynthesis and signaling at the onset of fruit ripening. Furthermore, some specific transcription factors (TFs) known as regulators of ethylene synthesis and sensibility (e.g. MADS-RIN, TAGL1, CNR and NOR) were also observed to be ABA responsive, which implied that ABA influenced ethylene action possibly through the regulation of these TFs expression. Our comprehensive physiological and molecular-level analysis shed light on the mechanism of cross-talk between ABA and ethylene during the process of tomato fruit ripening.

  10. Arabidopsis CPR5 Independently Regulates Seed Germination and Postgermination Arrest of Development through LOX Pathway and ABA Signaling

    PubMed Central

    Yang, Xiang; Wang, Yaqin; Su, Xiaojun; Du, Jinju; Yang, Chengwei

    2011-01-01

    The phytohormone abscisic acid (ABA) and the lipoxygenases (LOXs) pathway play important roles in seed germination and seedling growth and development. Here, we reported on the functional characterization of Arabidopsis CPR5 in the ABA signaling and LOX pathways. The cpr5 mutant was hypersensitive to ABA in the seed germination, cotyledon greening and root growth, whereas transgenic plants overexpressing CPR5 were insensitive. Genetic analysis demonstrated that CPR5 gene may be located downstream of the ABI1 in the ABA signaling pathway. However, the cpr5 mutant showed an ABA independent drought-resistant phenotype. It was also found that the cpr5 mutant was hypersensitive to NDGA and NDGA treatment aggravated the ABA-induced delay in the seed germination and cotyledon greening. Taken together, these results suggest that the CPR5 plays a regulatory role in the regulation of seed germination and early seedling growth through ABA and LOX pathways independently. PMID:21556325

  11. Wounding of potato tubers induces increases in ABA biosynthesis and catabolism and alters expression of ABA metabolic genes.

    PubMed

    Suttle, Jeffrey C; Lulai, Edward C; Huckle, Linda L; Neubauer, Jonathan D

    2013-04-15

    The effects of physical wounding on ABA biosynthesis and catabolism and expression of genes encoding key ABA metabolic enzymes were determined in potato tubers. An increase in ABA and ABA metabolite content was observed 48h after wounding and remained elevated through 96h. Wounding induced dramatic increases in the expression of the ABA metabolic genes encoding zeaxanthin epoxidase (ZEP), 9-cis-epoxycarotenoid dioxygenase (NCED), and ABA-8'-hydroxylase. Although the patterns of wound-induced expression of individual genes varied, increased gene expression was observed within 3h of wounding and remained elevated through 96h. An apparent correlation between expression of the gene encoding ZEP and the increase in ABA content suggested that the wound-induced increase in ABA biosynthesis was regulated by both substrate availability and increased NCED activity. Suppression of wound-induced jasmonic acid accumulation by rinsing the wounded tissue with water did not inhibit the subsequent increase in ABA content. Exogenous ethylene completely suppressed the wound-induced increase in ABA content and dramatically reduced wound-induced up-regulation of ABA metabolic genes. This study is the first to identify the molecular bases for increased ABA accumulation following physical trauma in potato tubers and highlights the complex physiological interactions between various wound-induced hormones.

  12. The Heat Stress Factor HSFA6b Connects ABA Signaling and ABA-Mediated Heat Responses1[OPEN

    PubMed Central

    Yang, Chen-Ru

    2016-01-01

    Heat stress response (HSR) is a conserved mechanism developed to increase the expression of heat shock proteins (HSPs) via a heat shock factor (HSF)-dependent mechanism. Signaling by the stress phytohormone abscisic acid (ABA) is involved in acquired thermotolerance as well. Analysis of Arabidopsis (Arabidopsis thaliana) microarray databases revealed that the expression of HSFA6b, a class A HSF, extensively increased with salinity, osmotic, and cold stresses, but not heat. Here, we show that HSFA6b plays a pivotal role in the response to ABA and in thermotolerance. Salt-inducible HSFA6b expression was down-regulated in ABA-insensitive and -deficient mutants; however, exogenous ABA application restored expression in ABA-deficient, but not -insensitive plants. Thus, ABA signaling is required for proper HSFA6b expression. A transcriptional activation assay of protoplasts revealed that ABA treatment and coexpression of an ABA signaling master effector, ABA-RESPONSIVE ELEMENT-BINDING PROTEIN1, could activate the HSFA6b promoter. In addition, HSFA6b directly bound to the promoter of DEHYDRATION-RESPONSIVE ELEMENT-BINDING PROTEIN2A and enhanced its expression. Analysis of ABA responses in seed germination, cotyledon greening, and root growth as well as salt and drought tolerance in HSFA6b-null, overexpression, and dominant negative mutants revealed that HSFA6b is a positive regulator participating in ABA-mediated salt and drought resistance. Thermoprotection tests showed that HSFA6b was required for thermotolerance acquisition. Our study reveals a network in which HSFA6b operates as a downstream regulator of the ABA-mediated stress response and is required for heat stress resistance. This new ABA-signaling pathway is integrated into the complex HSR network in planta. PMID:27493213

  13. Role of PP2C-mediated ABA signaling in the moss Physcomitrella patens.

    PubMed

    Sakata, Yoichi; Komatsu, Kenji; Taji, Teruaki; Tanaka, Shigeo

    2009-09-01

    Plant hormone abscisic acid (ABA) is found in a wide range of land plants, from mosses to angiosperms. However, our knowledge concerning the function of ABA is limited to some angiosperm plant species. We have shown that the basal land plant Physcomitrella patens and the model plant Arabidopsis thaliana share a conserved abscisic acid (ABA) signaling pathway mediated through ABI1-related type 2C protein phosphatases (PP2Cs). Ectopic expression of Arabidopsis abi1-1, a dominant allele of ABI1 that functions as a negative regulator of ABA signaling, or targeted disruption of Physcomitrella ABI1-related gene (PpABI1A) resulted in altered ABA sensitivity and abiotic stress tolerance of Physcomitrella, as demonstrated by osmostress and freezing stress. Moreover, transgenic Physcomitrella overexpressing abi1-1 showed altered morphogenesis. These transgenic plants had longer stem lengths compared to the wild type, and continuous growth of archegonia (female organ) with few sporophytes under non-stress conditions. Our results suggest that PP2C-mediated ABA signaling is involved in both the abiotic stress responses and developmental regulation of Physcomitrella.

  14. The NF-YC–RGL2 module integrates GA and ABA signalling to regulate seed germination in Arabidopsis

    PubMed Central

    Liu, Xu; Hu, Pengwei; Huang, Mingkun; Tang, Yang; Li, Yuge; Li, Ling; Hou, Xingliang

    2016-01-01

    The antagonistic crosstalk between gibberellic acid (GA) and abscisic acid (ABA) plays a pivotal role in the modulation of seed germination. However, the molecular mechanism of such phytohormone interaction remains largely elusive. Here we show that three Arabidopsis NUCLEAR FACTOR-Y C (NF-YC) homologues NF-YC3, NF-YC4 and NF-YC9 redundantly modulate GA- and ABA-mediated seed germination. These NF-YCs interact with the DELLA protein RGL2, a key repressor of GA signalling. The NF-YC–RGL2 module targets ABI5, a gene encoding a core component of ABA signalling, via specific CCAAT elements and collectively regulates a set of GA- and ABA-responsive genes, thus controlling germination. These results suggest that the NF-YC–RGL2–ABI5 module integrates GA and ABA signalling pathways during seed germination. PMID:27624486

  15. A Novel RNA-Binding Protein Involves ABA Signaling by Post-transcriptionally Repressing ABI2

    PubMed Central

    Xu, Jianwen; Chen, Yihan; Qian, Luofeng; Mu, Rong; Yuan, Xi; Fang, Huimin; Huang, Xi; Xu, Enshun; Zhang, Hongsheng; Huang, Ji

    2017-01-01

    The Stress Associated RNA-binding protein 1 (SRP1) repressed by ABA, salt and cold encodes a C2C2-type zinc finger protein in Arabidopsis. The knock-out mutation in srp1 reduced the sensitivity of seed to ABA and salt stress during germination and post-germinative growth stages. In contrast, SRP1-overexpressing seedlings were more sensitive to ABA and salt compared to wild type plants. In the presence of ABA, the transcript levels of ABA signaling and germination-related genes including ABI3. ABI5. EM1 and EM6 were less induced in srp1 compared to WT. Interestingly, expression of ABI2 encoding a protein phosphatase 2C protein were significantly up-regulated in srp1 mutants. By in vitro analysis, SRP1 was identified as a novel RNA-binding protein directly binding to 3′UTR of ABI2 mRNA. Moreover, transient expression assay proved the function of SRP1 in reducing the activity of luciferase whose coding sequence was fused with the ABI2 3’UTR. Together, it is suggested that SRP1 is involved in the ABA signaling by post-transcriptionally repressing ABI2 expression in Arabidopsis. PMID:28174577

  16. The Arabidopsis MIEL1 E3 ligase negatively regulates ABA signalling by promoting protein turnover of MYB96

    PubMed Central

    Lee, Hong Gil; Seo, Pil Joon

    2016-01-01

    The phytohormone abscisic acid (ABA) regulates plant responses to various environmental challenges. Controlled protein turnover is an important component of ABA signalling. Here we show that the RING-type E3 ligase MYB30-INTERACTING E3 LIGASE 1 (MIEL1) regulates ABA sensitivity by promoting MYB96 turnover in Arabidopsis. Germination of MIEL1-deficient mutant seeds is hypersensitive to ABA, whereas MIEL1-overexpressing transgenic seeds are less sensitive. MIEL1 can interact with MYB96, a regulator of ABA signalling, and stimulate its ubiquitination and degradation. Genetic analysis shows that MYB96 is epistatic to MIEL1 in the control of ABA sensitivity in seeds. While MIEL1 acts primarily via MYB96 in seed germination, MIEL1 regulates protein turnover of both MYB96 and MYB30 in vegetative tissues. We find that ABA regulates the expression of MYB30-responsive genes during pathogen infection and this regulation is partly dependent on MIEL1. These results suggest that MIEL1 may facilitate crosstalk between ABA and biotic stress signalling. PMID:27615387

  17. ESCRT-I Component VPS23A Affects ABA Signaling by Recognizing ABA Receptors for Endosomal Degradation.

    PubMed

    Yu, Feifei; Lou, Lijuan; Tian, Miaomiao; Li, Qingliang; Ding, Yanglin; Cao, Xiaoqiang; Wu, Yaorong; Belda-Palazon, Borja; Rodriguez, Pedro L; Yang, Shuhua; Xie, Qi

    2016-12-05

    Recent discovery of PYR/PYL/RCAR-type abscisic acid (ABA) receptors has become one of most significant advances in plant science in the past decade. In mammals, endosomal sorting acts as an important pathway to downregulate different types of receptors, but its role in plant hormone signaling is poorly understood. Here, we report that an ubiquitin E2-like protein, VPS23A, which is a key component of ESCRT-I, negatively regulates ABA signaling. VPS23A has epistatic relationship with PYR/PYL/RCAR-type ABA receptors and disruption of VPS23A enhanced the activity of key kinase OST1 in the ABA signaling pathway under ABA treatment. Moreover, VPS23A interacts with PYR1/PYLs and K63-linked diubiquitin, and PYL4 possesses K63-linked ubiquitinated modification in vivo. Further analysis revealed that VPS23A affects the subcellular localization of PYR1 and the stability of PYL4. Taken together, our results suggest that VPS23A affects PYR1/PYL4 via vacuole-mediated degradation, providing an advanced understanding of both the turnover of ABA receptors and ESCRTs in plant hormone signaling.

  18. A Role for Arabidopsis miR399f in Salt, Drought, and ABA Signaling

    PubMed Central

    Baek, Dongwon; Chun, Hyun Jin; Kang, Songhwa; Shin, Gilok; Park, Su Jung; Hong, Hyewon; Kim, Chanmin; Kim, Doh Hoon; Lee, Sang Yeol; Kim, Min Chul; Yun, Dae-Jin

    2016-01-01

    MiR399f plays a crucial role in maintaining phosphate homeostasis in Arabidopsis thaliana. Under phosphate starvation conditions, AtMYB2, which plays a role in plant salt and drought stress responses, directly regulates the expression of miR399f. In this study, we found that miR399f also participates in plant responses to abscisic acid (ABA), and to abiotic stresses including salt and drought. Salt and ABA treatment induced the expression of miR399f, as confirmed by histochemical analysis of promoter-GUS fusions. Transgenic Arabidopsis plants overexpressing miR399f (miR399f-OE) exhibited enhanced tolerance to salt stress and exogenous ABA, but hypersensitivity to drought. Our in silico analysis identified ABF3 and CSP41b as putative target genes of miR399f, and expression analysis revealed that mRNA levels of ABF3 and CSP41b decreased remarkably in miR399f-OE plants under salt stress and in response to treatment with ABA. Moreover, we showed that activation of stress-responsive gene expression in response to salt stress and ABA treatment was impaired in miR399f-OE plants. Thus, these results suggested that in addition to phosphate starvation signaling, miR399f might also modulates plant responses to salt, ABA, and drought, by regulating the expression of newly discovered target genes such as ABF3 and CSP41b. PMID:26674968

  19. Putrescine as a signal to modulate the indispensable ABA increase under cold stress

    PubMed Central

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

    2009-01-01

    Polyamines have been found to correlate frequently with biotic and abiotic insults, and their functional involvement in the plant responses to several stresses has been shown genetically with both gain and loss of function mutations. In spite of a large body of physiological and genetic data, the mode of action for polyamines at the molecular level still remains elusive. We have recently performed a detailed integrated analysis of polyamine metabolism under cold stress by means of metabolic studies, quantitative gene expression analyses, and gene inactivations, to characterize in more detail the role of polyamines in response to low temperature. Our data show a unique accumulation profile for putrescine compared to other polyamines, with a progressive increase upon cold stress treatment coincident with a similar transcriptional upregulation for the two arginine decarboxylase genes ADC1 and ADC2. Loss of function mutants adc1 and adc2 display reduced freezing tolerance and alterations in ABA content and ABA-dependent signalling pathways under low temperature, compared to wild type plants. Phenotypical reverse complementation tests for both adc and ABA-defective mutants support our conclusion that putrescine modulates ABA biosynthesis at the transcriptional level in response to low temperature thus uncovering a novel mode of action for polyamines as regulators of hormone biosynthesis. PMID:19721755

  20. The ABA signal transduction mechanism in commercial crops: learning from Arabidopsis.

    PubMed

    Ben-Ari, Giora

    2012-08-01

    The phytohormone abscisic acid (ABA) affects a wide range of stages of plant development as well as the plant's response to biotic and abiotic stresses. Manipulation of ABA signaling in commercial crops holds promising potential for improving crop yields. Several decades of research have been invested in attempts to identify the first components of the ABA signaling cascade. It was only in 2009, that two independent groups identified the PYR/PYL/RCAR protein family as the plant ABA receptor. This finding was followed by a surge of studies on ABA signal transduction, many of them using Arabidopsis as their model. The ABA signaling cascade was found to consist of a double-negative regulatory mechanism assembled from three protein families. These include the ABA receptors, the PP2C family of inhibitors, and the kinase family, SnRK2. It was found that ABA-bound PYR/RCARs inhibit PP2C activity, and that PP2Cs inactivate SnRK2s. Researchers today are examining how the elucidation of the ABA signaling cascade in Arabidopsis can be applied to improvements in commercial agriculture. In this article, we have attempted to review recent studies which address this issue. In it, we discuss various approaches useful in identifying the genetic and protein components involved. Finally, we suggest possible commercial applications of genetic manipulation of ABA signaling to improve crop yields.

  1. GSTF1 Gene Expression Analysis in Cultivated Wheat Plants under Salinity and ABA Treatments

    PubMed Central

    Niazi, Ali; Ramezani, Amin; Dinari, Ali

    2014-01-01

    Most plants encounter stress such as drought and salinity that adversely affect growth, development and crop productivity. The expression of the gene glutathione-s-transferases (GST) extends throughout various protective mechanisms in plants and allows them to adapt to unfavorable environmental conditions. GSTF1 (the first phi GSTFs class) gene expression patterns in the wheat cultivars Mahuti and Alamut were studied under salt and ABA treatments using a qRT-PCR technique. Results showed that gene expression patterns were significantly different in these two cultivars. Data showed that in Mahuti, there was an increase of transcript accumulation under salt and ABA treatments at 3h, 10h and 72h respectively. In Alamut, however, the pattern of transcript accumulation was different; the maximum was at 3h. In contrast, there were no significant differences observed between the cultivars for GSTF1 gene expression profiles at three levels of NaCl concentration (50, 100, and 200 mM) or in ABA (Abscisic Acid) treatment. It is likely that difference of gene expression patterns between the cultivars (Mahuti as a salt tolerant cultivar and Alamut as a salt sensitive cultivar) is due to distinct signaling pathways which activate GSTF1 expression. Lack of a significant difference between the GSTF1 gene expression profile under salt and ABA treatments suggests that the GSTF1 gene is not induced by stress stimuli. Of course it is possible that other levels of NaCl and ABA treatments cause a change in the GSTF1 gene. PMID:27843973

  2. Transcriptional regulation of SlPYL, SlPP2C, and SlSnRK2 gene families encoding ABA signal core components during tomato fruit development and drought stress

    PubMed Central

    Sun, Liang; Wang, Yan-Ping; Chen, Pei; Ren, Jie; Ji, Kai; Li, Qian; Li, Ping; Dai, Sheng-Jie; Leng, Ping

    2011-01-01

    In order to characterize the potential transcriptional regulation of core components of abscisic acid (ABA) signal transduction in tomato fruit development and drought stress, eight SlPYL (ABA receptor), seven SlPP2C (type 2C protein phosphatase), and eight SlSnRK2 (subfamily 2 of SNF1-related kinases) full-length cDNA sequences were isolated from the tomato nucleotide database of NCBI GenBank. All SlPYL, SlPP2C, and SlSnRK2 genes obtained are homologous to Arabidopsis AtPYL, AtPP2C, and AtSnRK2 genes, respectively. Based on phylogenetic analysis, SlPYLs and SlSnRK2s were clustered into three subfamilies/subclasses, and all SlPP2Cs belonged to PP2C group A. Within the SlPYL gene family, SlPYL1, SlPYL2, SlPYL3, and SlPYL6 were the major genes involved in the regulation of fruit development. Among them, SlPYL1 and SlPYL2 were expressed at high levels throughout the process of fruit development and ripening; SlPYL3 was strongly expressed at the immature green (IM) and mature green (MG) stages, while SlPYL6 was expressed strongly at the IM and red ripe (RR) stages. Within the SlPP2C gene family, the expression of SlPP2C, SlPP2C3, and SlPP2C4 increased after the MG stage; SlPP2C1 and SlPP2C5 peaked at the B3 stage, while SlPP2C2 and SlPP2C6 changed little during fruit development. Within the SlSnRK2 gene family, the expression of SlSnRK2.2, SlSnRK2.3, SlSnRK2.4, and SlSnRK2C was higher than that of other members during fruit development. Additionally, most SlPYL genes were down-regulated, while most SlPP2C and SlSnRK2 genes were up-regulated by dehydration in tomato leaf. PMID:21873532

  3. Transcriptional regulation of SlPYL, SlPP2C, and SlSnRK2 gene families encoding ABA signal core components during tomato fruit development and drought stress.

    PubMed

    Sun, Liang; Wang, Yan-Ping; Chen, Pei; Ren, Jie; Ji, Kai; Li, Qian; Li, Ping; Dai, Sheng-Jie; Leng, Ping

    2011-11-01

    In order to characterize the potential transcriptional regulation of core components of abscisic acid (ABA) signal transduction in tomato fruit development and drought stress, eight SlPYL (ABA receptor), seven SlPP2C (type 2C protein phosphatase), and eight SlSnRK2 (subfamily 2 of SNF1-related kinases) full-length cDNA sequences were isolated from the tomato nucleotide database of NCBI GenBank. All SlPYL, SlPP2C, and SlSnRK2 genes obtained are homologous to Arabidopsis AtPYL, AtPP2C, and AtSnRK2 genes, respectively. Based on phylogenetic analysis, SlPYLs and SlSnRK2s were clustered into three subfamilies/subclasses, and all SlPP2Cs belonged to PP2C group A. Within the SlPYL gene family, SlPYL1, SlPYL2, SlPYL3, and SlPYL6 were the major genes involved in the regulation of fruit development. Among them, SlPYL1 and SlPYL2 were expressed at high levels throughout the process of fruit development and ripening; SlPYL3 was strongly expressed at the immature green (IM) and mature green (MG) stages, while SlPYL6 was expressed strongly at the IM and red ripe (RR) stages. Within the SlPP2C gene family, the expression of SlPP2C, SlPP2C3, and SlPP2C4 increased after the MG stage; SlPP2C1 and SlPP2C5 peaked at the B3 stage, while SlPP2C2 and SlPP2C6 changed little during fruit development. Within the SlSnRK2 gene family, the expression of SlSnRK2.2, SlSnRK2.3, SlSnRK2.4, and SlSnRK2C was higher than that of other members during fruit development. Additionally, most SlPYL genes were down-regulated, while most SlPP2C and SlSnRK2 genes were up-regulated by dehydration in tomato leaf.

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

    PubMed Central

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

    2017-01-01

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

  5. Molecular basis of the core regulatory network in ABA responses: sensing, signaling and transport.

    PubMed

    Umezawa, Taishi; Nakashima, Kazuo; Miyakawa, Takuya; Kuromori, Takashi; Tanokura, Masaru; Shinozaki, Kazuo; Yamaguchi-Shinozaki, Kazuko

    2010-11-01

    ABA is a major phytohormone that regulates a broad range of plant traits and is especially important for adaptation to environmental conditions. Our understanding of the molecular basis of ABA responses in plants improved dramatically in 2009 and 2010, banner years for ABA research. There are three major components; PYR/PYL/ RCAR (an ABA receptor), type 2C protein phosphatase (PP2C; a negative regulator) and SNF1-related protein kinase 2 (SnRK2; a positive regulator), and they offer a double negative regulatory system, [PYR/PYL/RCAR-| PP2C-| SnRK2]. In the absence of ABA, PP2C inactivates SnRK2 by direct dephosphorylation. In response to environmental or developmental cues, ABA promotes the interaction of PYR/PYL/RCAR and PP2C, resulting in PP2C inhibition and SnRK2 activation. This signaling complex can work in both the nucleus and cytosol, as it has been shown that SnRK2 phosphorylates basic-domain leucine zipper (bZIP) transcription factors or membrane proteins. Several structural analyses of PYR/PYL/RCAR have provided the mechanistic basis for this 'core signaling' model, by elucidating the mechanism of ABA binding of receptors, or the 'gate-latch-lock' mechanism of interaction with PP2C in inhibiting activity. On the other hand, intercellular ABA transport had remained a major issue, as had intracellular ABA signaling. Recently, two plasma membrane-type ABC transporters were identified and shed light on the influx/efflux system of ABA, resolving how ABA is transported from cell to cell in plants. Our knowledge of ABA responses in plants has been greatly expanded from intracellular signaling to intercellular transport of ABA.

  6. ABA-dependent control of GIGANTEA signalling enables drought escape via up-regulation of FLOWERING LOCUS T in Arabidopsis thaliana

    PubMed Central

    Riboni, Matteo; Robustelli Test, Alice; Galbiati, Massimo; Tonelli, Chiara; Conti, Lucio

    2016-01-01

    One strategy deployed by plants to endure water scarcity is to accelerate the transition to flowering adaptively via the drought escape (DE) response. In Arabidopsis thaliana, activation of the DE response requires the photoperiodic response gene GIGANTEA (GI) and the florigen genes FLOWERING LOCUS T (FT) and TWIN SISTER OF FT (TSF). The phytohormone abscisic acid (ABA) is also required for the DE response, by promoting the transcriptional up-regulation of the florigen genes. The mode of interaction between ABA and the photoperiodic genes remains obscure. In this work we use a genetic approach to demonstrate that ABA modulates GI signalling and consequently its ability to activate the florigen genes. We also reveal that the ABA-dependent activation of FT, but not TSF, requires CONSTANS (CO) and that impairing ABA signalling dramatically reduces the expression of florigen genes with little effect on the CO transcript profile. ABA signalling thus has an impact on the core genes of photoperiodic signalling GI and CO by modulating their downstream function and/or activities rather than their transcript accumulation. In addition, we show that as well as promoting flowering, ABA simultaneously represses flowering, independent of the florigen genes. Genetic analysis indicates that the target of the repressive function of ABA is the flowering-promoting gene SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1 (SOC1), a transcription factor integrating floral cues in the shoot meristem. Our study suggests that variations in ABA signalling provide different developmental information that allows plants to co-ordinate the onset of the reproductive phase according to the available water resources. PMID:27733440

  7. Inhibition of FUSCA3 degradation at high temperature is dependent on ABA signaling and is regulated by the ABA/GA ratio.

    PubMed

    Chiu, Rex Shun; Saleh, Yazan; Gazzarrini, Sonia

    2016-11-01

    During seed imbibition at supra-optimal temperature, an increase in the abscisic acid (ABA)/gibberellin (GA) ratio imposes secondary dormancy to prevent germination (thermoinhibition). FUSCA3 (FUS3), a positive regulator of seed dormancy, accumulates in seeds imbibed at high temperature and increases ABA levels to inhibit germination. Recently, we showed that ABA inhibits FUS3 degradation at high temperature, and that ABA and high temperature also inhibit the ubiquitin-proteasome system, by dampening both proteasome activity and protein polyubiquitination. Here, we investigated the role of ABA signaling components and the ABA antagonizing hormone, GA, in the regulation of FUS3 levels. We show that the ABA receptor mutant, pyl1-1, is less sensitive to ABA and thermoinhibition. In this mutant background, FUS3 degradation in vitro is faster. Similarly, GA alleviates thermoinhibition and also increases FUS3 degradation. These results indicate that inhibition of FUS3 degradation at high temperature is dependent on a high ABA/GA ratio and a functional ABA signaling pathway. Thus, FUS3 constitutes an important node in ABA-GA crosstalk during germination at supra-optimal temperature.

  8. Molecular Mimicry Regulates ABA Signaling by SnRK2 Kinases and PP2C Phosphatases

    SciTech Connect

    Soon, Fen-Fen; Ng, Ley-Moy; Zhou, X. Edward; West, Graham M.; Kovach, Amanda; Tan, M.H. Eileen; Suino-Powell, Kelly M.; He, Yuanzheng; Xu, Yong; Chalmers, Michael J.; Brunzelle, Joseph S.; Zhang, Huiming; Yang, Huaiyu; Jiang, Hualiang; Li, Jun; Yong, Eu-Leong; Cutler, Sean; Zhu, Jian-Kang; Griffin, Patrick R.; Melcher, Karsten; Xu, H. Eric

    2014-10-02

    Abscisic acid (ABA) is an essential hormone for plants to survive environmental stresses. At the center of the ABA signaling network is a subfamily of type 2C protein phosphatases (PP2Cs), which form exclusive interactions with ABA receptors and subfamily 2 Snfl-related kinase (SnRK2s). Here, we report a SnRK2-PP2C complex structure, which reveals marked similarity in PP2C recognition by SnRK2 and ABA receptors. In the complex, the kinase activation loop docks into the active site of PP2C, while the conserved ABA-sensing tryptophan of PP2C inserts into the kinase catalytic cleft, thus mimicking receptor-PP2C interactions. These structural results provide a simple mechanism that directly couples ABA binding to SnRK2 kinase activation and highlight a new paradigm of kinase-phosphatase regulation through mutual packing of their catalytic sites.

  9. Molecular Mimicry Regulates ABA Signaling by SnRK2 Kinases and PP2C Phosphatases

    PubMed Central

    Soon, Fen-Fen; Ng, Ley-Moy; Zhou, X. Edward; West, Graham M.; Kovach, Amanda; Tan, M. H. Eileen; Suino-Powell, Kelly M.; He, Yuanzheng; Xu, Yong; Chalmers, Michael J.; Brunzelle, Joseph S.; Zhang, Huiming; Yang, Huaiyu; Jiang, Hualiang; Li, Jun; Yong, Eu-Leong; Cutler, Sean; Zhu, Jian-Kang; Griffin, Patrick R.; Melcher, Karsten; Xu, H. Eric

    2013-01-01

    Abscisic acid (ABA) is an essential hormone for plants to survive environmental stresses. At the center of the ABA signaling network is a subfamily of type 2C protein phosphatases (PP2Cs), which form exclusive interactions with ABA receptors and subfamily 2 Snfl-related kinase (SnRK2s). Here, we report a SnRK2-PP2C complex structure, which reveals marked similarity in PP2C recognition by SnRK2 and ABA receptors. In the complex, the kinase activation loop docks into the active site of PP2C, while the conserved ABA-sensing tryptophan of PP2C inserts into the kinase catalytic cleft, thus mimicking receptor-PP2C interactions. These structural results provide a simple mechanism that directly couples ABA binding to SnRK2 kinase activation and highlight a new paradigm of kinase-phosphatase regulation through mutual packing of their catalytic sites. PMID:22116026

  10. Molecular mimicry regulates ABA signaling by SnRK2 kinases and PP2C phosphatases.

    PubMed

    Soon, Fen-Fen; Ng, Ley-Moy; Zhou, X Edward; West, Graham M; Kovach, Amanda; Tan, M H Eileen; Suino-Powell, Kelly M; He, Yuanzheng; Xu, Yong; Chalmers, Michael J; Brunzelle, Joseph S; Zhang, Huiming; Yang, Huaiyu; Jiang, Hualiang; Li, Jun; Yong, Eu-Leong; Cutler, Sean; Zhu, Jian-Kang; Griffin, Patrick R; Melcher, Karsten; Xu, H Eric

    2012-01-06

    Abscisic acid (ABA) is an essential hormone for plants to survive environmental stresses. At the center of the ABA signaling network is a subfamily of type 2C protein phosphatases (PP2Cs), which form exclusive interactions with ABA receptors and subfamily 2 Snfl-related kinase (SnRK2s). Here, we report a SnRK2-PP2C complex structure, which reveals marked similarity in PP2C recognition by SnRK2 and ABA receptors. In the complex, the kinase activation loop docks into the active site of PP2C, while the conserved ABA-sensing tryptophan of PP2C inserts into the kinase catalytic cleft, thus mimicking receptor-PP2C interactions. These structural results provide a simple mechanism that directly couples ABA binding to SnRK2 kinase activation and highlight a new paradigm of kinase-phosphatase regulation through mutual packing of their catalytic sites.

  11. Local root abscisic acid (ABA) accumulation depends on the spatial distribution of soil moisture in potato: implications for ABA signalling under heterogeneous soil drying

    PubMed Central

    Puértolas, Jaime; Conesa, María R.; Ballester, Carlos; Dodd, Ian C.

    2015-01-01

    Patterns of root abscisic acid (ABA) accumulation ([ABA]root), root water potential (Ψroot), and root water uptake (RWU), and their impact on xylem sap ABA concentration ([X-ABA]) were measured under vertical partial root-zone drying (VPRD, upper compartment dry, lower compartment wet) and horizontal partial root-zone drying (HPRD, two lateral compartments: one dry, the other wet) of potato (Solanum tuberosum L.). When water was withheld from the dry compartment for 0–10 d, RWU and Ψroot were similarly lower in the dry compartment when soil volumetric water content dropped below 0.22cm3 cm–3 for both spatial distributions of soil moisture. However, [ABA]root increased in response to decreasing Ψroot in the dry compartment only for HPRD, resulting in much higher ABA accumulation than in VPRD. The position of the sampled roots (~4cm closer to the surface in the dry compartment of VPRD than in HPRD) might account for this difference, since older (upper) roots may accumulate less ABA in response to decreased Ψroot than younger (deeper) roots. This would explain differences in root ABA accumulation patterns under vertical and horizontal soil moisture gradients reported in the literature. In our experiment, these differences in root ABA accumulation did not influence [X-ABA], since the RWU fraction (and thus ABA export to shoots) from the dry compartment dramatically decreased simultaneously with any increase in [ABA]root. Thus, HPRD might better trigger a long-distance ABA signal than VPRD under conditions allowing simultaneous high [ABA]root and relatively high RWU fraction. PMID:25547916

  12. Local root abscisic acid (ABA) accumulation depends on the spatial distribution of soil moisture in potato: implications for ABA signalling under heterogeneous soil drying.

    PubMed

    Puértolas, Jaime; Conesa, María R; Ballester, Carlos; Dodd, Ian C

    2015-04-01

    Patterns of root abscisic acid (ABA) accumulation ([ABA]root), root water potential (Ψroot), and root water uptake (RWU), and their impact on xylem sap ABA concentration ([X-ABA]) were measured under vertical partial root-zone drying (VPRD, upper compartment dry, lower compartment wet) and horizontal partial root-zone drying (HPRD, two lateral compartments: one dry, the other wet) of potato (Solanum tuberosum L.). When water was withheld from the dry compartment for 0-10 d, RWU and Ψroot were similarly lower in the dry compartment when soil volumetric water content dropped below 0.22cm(3) cm(-3) for both spatial distributions of soil moisture. However, [ABA]root increased in response to decreasing Ψroot in the dry compartment only for HPRD, resulting in much higher ABA accumulation than in VPRD. The position of the sampled roots (~4cm closer to the surface in the dry compartment of VPRD than in HPRD) might account for this difference, since older (upper) roots may accumulate less ABA in response to decreased Ψroot than younger (deeper) roots. This would explain differences in root ABA accumulation patterns under vertical and horizontal soil moisture gradients reported in the literature. In our experiment, these differences in root ABA accumulation did not influence [X-ABA], since the RWU fraction (and thus ABA export to shoots) from the dry compartment dramatically decreased simultaneously with any increase in [ABA]root. Thus, HPRD might better trigger a long-distance ABA signal than VPRD under conditions allowing simultaneous high [ABA]root and relatively high RWU fraction.

  13. Inactivation of PYR/PYL/RCAR ABA receptors by tyrosine nitration may enable rapid inhibition of ABA signaling by nitric oxide in plants.

    PubMed

    Castillo, Mari-Cruz; Lozano-Juste, Jorge; González-Guzmán, Miguel; Rodriguez, Lesia; Rodriguez, Pedro L; León, José

    2015-09-01

    Abscisic acid (ABA) is a phytohormone that inhibits growth and enhances adaptation to stress in plants. ABA perception and signaling rely on its binding to receptors of the pyrabactin resistance1/PYR1-like/regulatory components of ABA receptors (PYR/PYL/RCAR) family, the subsequent inhibition of clade A type 2C protein phosphatases (PP2Cs), and the phosphorylation of ion channels and transcription factors by protein kinases of the SnRK2 family. Nitric oxide (NO) may inhibit ABA signaling because NO-deficient plants are hypersensitive to ABA. Regulation by NO often involves posttranslational modification of proteins. Mass spectrometry analysis of ABA receptors expressed in plants and recombinant receptors modified in vitro revealed that the receptors were nitrated at tyrosine residues and S-nitrosylated at cysteine residues. In an in vitro ABA-induced, PP2C inhibition assay, tyrosine nitration reduced receptor activity, whereas S-nitrosylated receptors were fully capable of ABA-induced inhibition of the phosphatase. PYR/PYL/RCAR proteins with nitrated tyrosine, which is an irreversible covalent modification, were polyubiquitylated and underwent proteasome-mediated degradation. We propose that tyrosine nitration, which requires NO and superoxide anions, is a rapid mechanism by which NO limits ABA signaling under conditions in which NO and reactive oxygen species are both produced.

  14. Catalytic mechanism and kinase interactions of ABA-signaling PP2C phosphatases.

    PubMed

    Zhou, X Edward; Soon, Fen-Fen; Ng, Ley-Moy; Kovach, Amanda; Suino-Powell, Kelly M; Li, Jun; Yong, Eu-Leong; Zhu, Jian-Kang; Xu, H Eric; Melcher, Karsten

    2012-05-01

    Abscisic acid (ABA) is an essential hormone that controls plant growth, development and responses to abiotic stresses. ABA signaling is mediated by type 2C protein phosphatases (PP2Cs), including HAB1 and ABI2, which inhibit stress-activated SnRK2 kinases and whose activity is regulated by ABA and ABA receptors. Based on biochemical data and our previously determined crystal structures of ABI2 and the SnRK2.6-HAB1 complex, we present the catalytic mechanism of PP2C and provide new insight into PP2C-SnRK2 interactions and possible roles of other SnRK2 kinases in ABA signaling.

  15. Pepper CaREL1, a ubiquitin E3 ligase, regulates drought tolerance via the ABA-signalling pathway.

    PubMed

    Lim, Chae Woo; Park, Chanmi; Kim, Jung-Hyun; Joo, Hyunhee; Hong, Eunji; Lee, Sung Chul

    2017-03-28

    Drought stress conditions in soil or air hinder plant growth and development. Here, we report that the hot pepper (C apsicum a nnuum) RING type E3 Ligase 1 gene (CaREL1) is essential to the drought stress response. CaREL1 encodes a cytoplasmic- and nuclear-localized protein with E3 ligase activity. CaREL1 expression was induced by abscisic acid (ABA) and drought. CaREL1 contains a C3H2C3-type RING finger motif, which functions in ubiquitination of the target protein. We used CaREL1-silenced pepper plants and CaREL1-overexpressing (OX) transgenic Arabidopsis plants to evaluate the in vivo function of CaREL1 in response to drought stress and ABA treatment. CaREL1-silenced pepper plants displayed a drought-tolerant phenotype characterized by ABA hypersensitivity. In contrast, CaREL1-OX plants exhibited ABA hyposensitivity during the germination, seedling, and adult stages. In addition, plant growth was severely impaired under drought stress conditions, via a high level of transpirational water loss and decreased stomatal closure. Quantitative RT-PCR analyses revealed that ABA-related drought stress responsive genes were more weakly expressed in CaREL1-OX plants than in wild-type plants, indicating that CaREL1 functions in the drought stress response via the ABA-signalling pathway. Taken together, our results indicate that CaREL1 functions as a negative regulator of ABA-mediated drought stress tolerance.

  16. Type B Heterotrimeric G Protein γ-Subunit Regulates Auxin and ABA Signaling in Tomato.

    PubMed

    Subramaniam, Gayathery; Trusov, Yuri; Lopez-Encina, Carlos; Hayashi, Satomi; Batley, Jacqueline; Botella, José Ramón

    2016-02-01

    Heterotrimeric G proteins composed of α, β, and γ subunits are central signal transducers mediating the cellular response to multiple stimuli in most eukaryotes. Gγ subunits provide proper cellular localization and functional specificity to the heterotrimer complex. Plant Gγ subunits, divided into three structurally distinct types, are more diverse than their animal counterparts. Type B Gγ subunits, lacking a carboxyl-terminal isoprenylation motif, are found only in flowering plants. We present the functional characterization of type B Gγ subunit (SlGGB1) in tomato (Solanum lycopersicum). We show that SlGGB1 is the most abundant Gγ subunit in tomato and strongly interacts with the Gβ subunit. Importantly, the green fluorescent protein-SlGGB1 fusion protein as well as the carboxyl-terminal yellow fluorescent protein-SlGGB1/amino-terminal yellow fluorescent protein-Gβ heterodimer were localized in the plasma membrane, nucleus, and cytoplasm. RNA interference-mediated silencing of SlGGB1 resulted in smaller seeds, higher number of lateral roots, and pointy fruits. The silenced lines were hypersensitive to exogenous auxin, while levels of endogenous auxins were lower or similar to those of the wild type. SlGGB1-silenced plants also showed strong hyposensitivity to abscisic acid (ABA) during seed germination but not in other related assays. Transcriptome analysis of the transgenic seeds revealed abnormal expression of genes involved in ABA sensing, signaling, and response. We conclude that the type B Gγ subunit SlGGB1 mediates auxin and ABA signaling in tomato.

  17. Investigating the role of ABA signaling in wheat drought tolerance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Allohexaploid wheat (Triticum aestivum L.) is one of the three major cereal crops supporting human nutrition. Because wheat is often grown under dryland conditions, it is subject to losses as a result of drought stress. This study examines the role of the plant hormone ABA is wheat responses to wate...

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

    PubMed

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

    2015-11-27

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

  19. AsHSP17, a creeping bentgrass small heat shock protein modulates plant photosynthesis and ABA-dependent and independent signalling to attenuate plant response to abiotic stress.

    PubMed

    Sun, Xinbo; Sun, Chunyu; Li, Zhigang; Hu, Qian; Han, Liebao; Luo, Hong

    2016-06-01

    Heat shock proteins (HSPs) are molecular chaperones that accumulate in response to heat and other abiotic stressors. Small HSPs (sHSPs) belong to the most ubiquitous HSP subgroup with molecular weights ranging from 12 to 42 kDa. We have cloned a new sHSP gene, AsHSP17 from creeping bentgrass (Agrostis stolonifera) and studied its role in plant response to environmental stress. AsHSP17 encodes a protein of 17 kDa. Its expression was strongly induced by heat in both leaf and root tissues, and by salt and abscisic acid (ABA) in roots. Transgenic Arabidopsis plants constitutively expressing AsHSP17 exhibited enhanced sensitivity to heat and salt stress accompanied by reduced leaf chlorophyll content and decreased photosynthesis under both normal and stressed conditions compared to wild type. Overexpression of AsHSP17 also led to hypersensitivity to exogenous ABA and salinity during germination and post-germinative growth. Gene expression analysis indicated that AsHSP17 modulates expression of photosynthesis-related genes and regulates ABA biosynthesis, metabolism and ABA signalling as well as ABA-independent stress signalling. Our results suggest that AsHSP17 may function as a protein chaperone to negatively regulate plant responses to adverse environmental stresses through modulating photosynthesis and ABA-dependent and independent signalling pathways.

  20. The Arabidopsis transcription factor ABIG1 relays ABA signaled growth inhibition and drought induced senescence

    PubMed Central

    Liu, Tie; Longhurst, Adam D; Talavera-Rauh, Franklin; Hokin, Samuel A; Barton, M Kathryn

    2016-01-01

    Drought inhibits plant growth and can also induce premature senescence. Here we identify a transcription factor, ABA INSENSITIVE GROWTH 1 (ABIG1) required for abscisic acid (ABA) mediated growth inhibition, but not for stomatal closure. ABIG1 mRNA levels are increased both in response to drought and in response to ABA treatment. When treated with ABA, abig1 mutants remain greener and produce more leaves than comparable wild-type plants. When challenged with drought, abig1 mutants have fewer yellow, senesced leaves than wild-type. Induction of ABIG1 transcription mimics ABA treatment and regulates a set of genes implicated in stress responses. We propose a model in which drought acts through ABA to increase ABIG1 transcription which in turn restricts new shoot growth and promotes leaf senescence. The results have implications for plant breeding: the existence of a mutant that is both ABA resistant and drought resistant points to new strategies for isolating drought resistant genetic varieties. DOI: http://dx.doi.org/10.7554/eLife.13768.001 PMID:27697148

  1. Expression analysis of abscisic acid (ABA) and metabolic signalling factors in developing endosperm and embryo of barley☆

    PubMed Central

    Chen, Zhiwei; Huang, Jianhua; Muttucumaru, Nira; Powers, Stephen J.; Halford, Nigel G.

    2013-01-01

    The expression of genes encoding components of ABA and metabolic signalling pathways in developing barley endosperm and embryo was investigated. The genes included HvRCAR35_47387 and HvRCAR35_2538 (encoding ABA receptors), HvABI1d (protein phosphatase 2C), HvSnRK2.4, HvSnRK2.6 and HvPKABA1 (SnRK2-type protein kinases) and HvABI5 (ABA response element binding protein; AREBP), as well as two genes encoding SnRK1-type protein kinases. Both SnRK1 and SnRK2 phosphorylate AREBPs, but SnRK2 is activated by ABA whereas SnRK1 may be broken down. Multiple cereal AREBPs with two conserved SnRK1/2 target sites and another class of BZIP transcription factors with SnRK1/2 binding sites, including HvBLZ1, were identified. Barley grain (cv. Triumph) was sampled at 15, 20, 25 and 30 days post-anthesis (dpa). HvRCAR35_47387, HvABI1d, HvSnRK2.4 and HvABI5 were expressed highly in the endosperm but at much lower levels in the embryo. Conversely, HvPKABA1 and HvRCAR35_2538 were expressed at higher levels in the embryo than the endosperm, while HvSnRK2.6 was expressed at similar levels in both. HvRCAR35_47387, HvABI1d, HvSnRK2.4 and HvABI5 all peaked in expression in the endosperm at 20 dpa. A model is proposed in which ABA brings about a transition from a SnRK1-dominated state in the endosperm during grain filling to a SnRK2-dominated state during maturation. PMID:24748715

  2. Expression analysis of abscisic acid (ABA) and metabolic signalling factors in developing endosperm and embryo of barley.

    PubMed

    Chen, Zhiwei; Huang, Jianhua; Muttucumaru, Nira; Powers, Stephen J; Halford, Nigel G

    2013-09-01

    The expression of genes encoding components of ABA and metabolic signalling pathways in developing barley endosperm and embryo was investigated. The genes included HvRCAR35_47387 and HvRCAR35_2538 (encoding ABA receptors), HvABI1d (protein phosphatase 2C), HvSnRK2.4, HvSnRK2.6 and HvPKABA1 (SnRK2-type protein kinases) and HvABI5 (ABA response element binding protein; AREBP), as well as two genes encoding SnRK1-type protein kinases. Both SnRK1 and SnRK2 phosphorylate AREBPs, but SnRK2 is activated by ABA whereas SnRK1 may be broken down. Multiple cereal AREBPs with two conserved SnRK1/2 target sites and another class of BZIP transcription factors with SnRK1/2 binding sites, including HvBLZ1, were identified. Barley grain (cv. Triumph) was sampled at 15, 20, 25 and 30 days post-anthesis (dpa). HvRCAR35_47387, HvABI1d, HvSnRK2.4 and HvABI5 were expressed highly in the endosperm but at much lower levels in the embryo. Conversely, HvPKABA1 and HvRCAR35_2538 were expressed at higher levels in the embryo than the endosperm, while HvSnRK2.6 was expressed at similar levels in both. HvRCAR35_47387, HvABI1d, HvSnRK2.4 and HvABI5 all peaked in expression in the endosperm at 20 dpa. A model is proposed in which ABA brings about a transition from a SnRK1-dominated state in the endosperm during grain filling to a SnRK2-dominated state during maturation.

  3. CHLH/GUN5 Function in Tetrapyrrole Metabolism Is Correlated with Plastid Signaling but not ABA Responses in Guard Cells

    PubMed Central

    Ibata, Harue; Nagatani, Akira; Mochizuki, Nobuyoshi

    2016-01-01

    Expression of Photosynthesis-Associated Nuclear Genes (PhANGs) is controlled by environmental stimuli and plastid-derived signals (“plastid signals”) transmitting the developmental and functional status of plastids to the nucleus. Arabidopsis genomes uncoupled (gun) mutants exhibit defects in plastid signaling, leading to ectopic expression of PhANGs in the absence of chloroplast development. GUN5 encodes the plastid-localized Mg-chelatase enzyme subunit (CHLH), and recent studies suggest that CHLH is a multifunctional protein involved in tetrapyrrole biosynthesis, plastid signaling and ABA responses in guard cells. To understand the basis of CHLH multifunctionality, we investigated 15 gun5 missense mutant alleles and transgenic lines expressing a series of truncated CHLH proteins in a severe gun5 allele (cch) background (tCHLHs, 10 different versions). Here, we show that Mg-chelatase function and plastid signaling are generally correlated; in contrast, based on the analysis of the gun5 missense mutant alleles, ABA-regulated stomatal control is distinct from these two other functions. We found that none of the tCHLHs could restore plastid-signaling or Mg-chelatase functions. Additionally, we found that both the C-terminal half and N-terminal half of CHLH function in ABA-induced stomatal movement. PMID:27872634

  4. Genome-Wide Analysis of the bZIP Gene Family Identifies Two ABI5-Like bZIP Transcription Factors, BrABI5a and BrABI5b, as Positive Modulators of ABA Signalling in Chinese Cabbage

    PubMed Central

    Hu, Xiaochen; Sun, Congcong; Li, Yanlin; Wang, Dandan; Wang, Qinhu; Pei, Guoliang; Zhang, Yanfeng; Guo, Aiguang; Zhao, Huixian; Lu, Haibin; Mu, Xiaoqian; Hu, Jingjiang; Zhou, Xiaona; Xie, Chang Gen

    2016-01-01

    bZIP (basic leucine zipper) transcription factors coordinate plant growth and development and control responses to environmental stimuli. The genome of Chinese cabbage (Brassica rapa) encodes 136 putative bZIP transcription factors. The bZIP transcription factors in Brassica rapa (BrbZIP) are classified into 10 subfamilies. Phylogenetic relationship analysis reveals that subfamily A consists of 23 BrbZIPs. Two BrbZIPs within subfamily A, Bra005287 and Bra017251, display high similarity to ABI5 (ABA Insensitive 5). Expression of subfamily A BrbZIPs, like BrABI5a (Bra005287/BrbZIP14) and BrABI5b (Bra017251/BrbZIP13), are significantly induced by the plant hormone ABA. Subcellular localization assay reveal that both BrABI5a and BrABI5b have a nuclear localization. BrABI5a and BrABI5b could directly stimulate ABA Responsive Element-driven HIS (a HIS3 reporter gene, which confers His prototrophy) or LUC (LUCIFERASE) expression in yeast and Arabidopsis protoplast. Deletion of the bZIP motif abolished BrABI5a and BrABI5b transcriptional activity. The ABA insensitive phenotype of Arabidopsis abi5-1 is completely suppressed in transgenic lines expressing BrABI5a or BrABI5b. Overall, these results suggest that ABI5 orthologs, BrABI5a and BrABI5b, have key roles in ABA signalling in Chinese cabbage. PMID:27414644

  5. Calcium-dependent oligomerization of CAR proteins at cell membrane modulates ABA signaling

    PubMed Central

    Diaz, Maira; Sanchez-Barrena, Maria Jose; Gonzalez-Rubio, Juana Maria; Rodriguez, Lesia; Fernandez, Daniel; Antoni, Regina; Yunta, Cristina; Belda-Palazon, Borja; Gonzalez-Guzman, Miguel; Peirats-Llobet, Marta; Menendez, Margarita; Boskovic, Jasminka; Marquez, Jose A.; Rodriguez, Pedro L.; Albert, Armando

    2016-01-01

    Regulation of ion transport in plants is essential for cell function. Abiotic stress unbalances cell ion homeostasis, and plants tend to readjust it, regulating membrane transporters and channels. The plant hormone abscisic acid (ABA) and the second messenger Ca2+ are central in such processes, as they are involved in the regulation of protein kinases and phosphatases that control ion transport activity in response to environmental stimuli. The identification and characterization of the molecular mechanisms underlying the effect of ABA and Ca2+ signaling pathways on membrane function are central and could provide opportunities for crop improvement. The C2-domain ABA-related (CAR) family of small proteins is involved in the Ca2+-dependent recruitment of the pyrabactin resistance 1/PYR1-like (PYR/PYL) ABA receptors to the membrane. However, to fully understand CAR function, it is necessary to define a molecular mechanism that integrates Ca2+ sensing, membrane interaction, and the recognition of the PYR/PYL interacting partners. We present structural and biochemical data showing that CARs are peripheral membrane proteins that functionally cluster on the membrane and generate strong positive membrane curvature in a Ca2+-dependent manner. These features represent a mechanism for the generation, stabilization, and/or specific recognition of membrane discontinuities. Such structures may act as signaling platforms involved in the recruitment of PYR/PYL receptors and other signaling components involved in cell responses to stress. PMID:26719420

  6. Calcium-dependent oligomerization of CAR proteins at cell membrane modulates ABA signaling.

    PubMed

    Diaz, Maira; Sanchez-Barrena, Maria Jose; Gonzalez-Rubio, Juana Maria; Rodriguez, Lesia; Fernandez, Daniel; Antoni, Regina; Yunta, Cristina; Belda-Palazon, Borja; Gonzalez-Guzman, Miguel; Peirats-Llobet, Marta; Menendez, Margarita; Boskovic, Jasminka; Marquez, Jose A; Rodriguez, Pedro L; Albert, Armando

    2016-01-19

    Regulation of ion transport in plants is essential for cell function. Abiotic stress unbalances cell ion homeostasis, and plants tend to readjust it, regulating membrane transporters and channels. The plant hormone abscisic acid (ABA) and the second messenger Ca(2+) are central in such processes, as they are involved in the regulation of protein kinases and phosphatases that control ion transport activity in response to environmental stimuli. The identification and characterization of the molecular mechanisms underlying the effect of ABA and Ca(2+) signaling pathways on membrane function are central and could provide opportunities for crop improvement. The C2-domain ABA-related (CAR) family of small proteins is involved in the Ca(2+)-dependent recruitment of the pyrabactin resistance 1/PYR1-like (PYR/PYL) ABA receptors to the membrane. However, to fully understand CAR function, it is necessary to define a molecular mechanism that integrates Ca(2+) sensing, membrane interaction, and the recognition of the PYR/PYL interacting partners. We present structural and biochemical data showing that CARs are peripheral membrane proteins that functionally cluster on the membrane and generate strong positive membrane curvature in a Ca(2+)-dependent manner. These features represent a mechanism for the generation, stabilization, and/or specific recognition of membrane discontinuities. Such structures may act as signaling platforms involved in the recruitment of PYR/PYL receptors and other signaling components involved in cell responses to stress.

  7. Activation of dimeric ABA receptors elicits guard cell closure, ABA-regulated gene expression, and drought tolerance

    PubMed Central

    Okamoto, Masanori; Peterson, Francis C.; Defries, Andrew; Park, Sang-Youl; Endo, Akira; Nambara, Eiji; Volkman, Brian F.; Cutler, Sean R.

    2013-01-01

    Abscisic acid (ABA) is an essential molecule in plant abiotic stress responses. It binds to soluble pyrabactin resistance1/PYR1-like/regulatory component of ABA receptor receptors and stabilizes them in a conformation that inhibits clade A type II C protein phosphatases; this leads to downstream SnRK2 kinase activation and numerous cellular outputs. We previously described the synthetic naphthalene sulfonamide ABA agonist pyrabactin, which activates seed ABA responses but fails to trigger substantial responses in vegetative tissues in Arabidopsis thaliana. Here we describe quinabactin, a sulfonamide ABA agonist that preferentially activates dimeric ABA receptors and possesses ABA-like potency in vivo. In Arabidopsis, the transcriptional responses induced by quinabactin are highly correlated with those induced by ABA treatments. Quinabactin treatments elicit guard cell closure, suppress water loss, and promote drought tolerance in adult Arabidopsis and soybean plants. The effects of quinabactin are sufficiently similar to those of ABA that it is able to rescue multiple phenotypes observed in the ABA-deficient mutant aba2. Genetic analyses show that quinabactin’s effects in vegetative tissues are primarily mediated by dimeric ABA receptors. A PYL2-quinabactin-HAB1 X-ray crystal structure solved at 1.98-Å resolution shows that quinabactin forms a hydrogen bond with the receptor/PP2C “lock” hydrogen bond network, a structural feature absent in pyrabactin-receptor/PP2C complexes. Our results demonstrate that ABA receptors can be chemically controlled to enable plant protection against water stress and define the dimeric receptors as key targets for chemical modulation of vegetative ABA responses. PMID:23818638

  8. Activation of dimeric ABA receptors elicits guard cell closure, ABA-regulated gene expression, and drought tolerance.

    PubMed

    Okamoto, Masanori; Peterson, Francis C; Defries, Andrew; Park, Sang-Youl; Endo, Akira; Nambara, Eiji; Volkman, Brian F; Cutler, Sean R

    2013-07-16

    Abscisic acid (ABA) is an essential molecule in plant abiotic stress responses. It binds to soluble pyrabactin resistance1/PYR1-like/regulatory component of ABA receptor receptors and stabilizes them in a conformation that inhibits clade A type II C protein phosphatases; this leads to downstream SnRK2 kinase activation and numerous cellular outputs. We previously described the synthetic naphthalene sulfonamide ABA agonist pyrabactin, which activates seed ABA responses but fails to trigger substantial responses in vegetative tissues in Arabidopsis thaliana. Here we describe quinabactin, a sulfonamide ABA agonist that preferentially activates dimeric ABA receptors and possesses ABA-like potency in vivo. In Arabidopsis, the transcriptional responses induced by quinabactin are highly correlated with those induced by ABA treatments. Quinabactin treatments elicit guard cell closure, suppress water loss, and promote drought tolerance in adult Arabidopsis and soybean plants. The effects of quinabactin are sufficiently similar to those of ABA that it is able to rescue multiple phenotypes observed in the ABA-deficient mutant aba2. Genetic analyses show that quinabactin's effects in vegetative tissues are primarily mediated by dimeric ABA receptors. A PYL2-quinabactin-HAB1 X-ray crystal structure solved at 1.98-Å resolution shows that quinabactin forms a hydrogen bond with the receptor/PP2C "lock" hydrogen bond network, a structural feature absent in pyrabactin-receptor/PP2C complexes. Our results demonstrate that ABA receptors can be chemically controlled to enable plant protection against water stress and define the dimeric receptors as key targets for chemical modulation of vegetative ABA responses.

  9. MYB96 shapes the circadian gating of ABA signaling in Arabidopsis

    PubMed Central

    Lee, Hong Gil; Mas, Paloma; Seo, Pil Joon

    2016-01-01

    Circadian clocks regulate the rhythms of biological activities with a period of approximately 24-hours and synchronize plant metabolism and physiology with the environmental cycles. The clock also gates responses to environmental stresses to maximize fitness advantages. Here we report that the MYB96 transcription factor is connected with the clock oscillator to shape the circadian gating of abscisic acid (ABA) responses. MYB96 directly binds to the TIMING OF CAB EXPRESSION 1 (TOC1) promoter to positively regulate its expression. The use of myb96 mutant plants shows that this regulation is essential for the gated induction of TOC1 by ABA. In turn, MYB96 induction by ABA is also altered in toc1-3 mutant plants. The increased tolerance to drought of MYB96 over-expressing plants is decreased in the toc1-3 mutant background, suggesting that MYB96 and TOC1 intersect the circadian clock and ABA signaling. The MYB96-TOC1 function might be also regulated by the clock component CIRCADIAN CLOCK-ASSOCIATED 1 (CCA1), which binds to the MYB96 promoter and alters its circadian expression. Thus, a complex circuitry of CCA1-MYB96-TOC1 regulatory interactions provides the mechanistic basis underlying the connection between circadian and stress signaling to optimize plant fitness to ambient stresses. PMID:26725725

  10. Functional dissection of an abscisic acid (ABA)-inducible gene reveals two independent ABA-responsive complexes each containing a G-box and a novel cis-acting element.

    PubMed Central

    Shen, Q; Ho, T H

    1995-01-01

    To elucidate the mechanism by which abscisic acid (ABA) regulates gene expression, the promoter of the barley ABA-responsive HVA22 gene has been analyzed by both loss- and gain-of-function studies. Previous reports indicate that G-box sequences, which are present in genes responding to a variety of environmental and physiological cues, are involved in ABA response. However, our data suggest that G-box sequences are necessary but not sufficient for ABA response. Instead, an ABA response complex consisting of a G-box, namely, ABRE3 (GCCACGTACA), and a novel coupling element, CE1 (TGCCACCGG), is sufficient for high-level ABA induction, and replacement of either of these sequences abolishes ABA responsiveness. We suggest that the interaction between G-box sequences, such as ABRE3 in the HVA22 gene, and CE-type sequences determines the specificity in ABA-regulated gene expression. Our results also demonstrate that the ABA response complex is the minimal promoter unit governing high-level ABA induction; four copies of this 49-bp-long complex linked to a minimal promoter can confer more than 100-fold ABA-induced gene expression. In addition to ABA response complex 1, composed of ABRE3 and CE1, the HVA22 promoter contains another ABA response complex. The ABA responsiveness of this ABA response complex 2 relies on the interaction of G-box (ABRE2; CGCACGTGTC) with another yet unidentified coupling element. These two complexes contribute incrementally to the expression level of HVA22 in response to ABA. PMID:7734964

  11. PLASTID MOVEMENT IMPAIRED1 mediates ABA sensitivity during germination and implicates ABA in light-mediated Chloroplast movements.

    PubMed

    Rojas-Pierce, Marcela; Whippo, Craig W; Davis, Phillip A; Hangarter, Roger P; Springer, Patricia S

    2014-10-01

    The plant hormone abscisic acid (ABA) controls many aspects of plant growth and development, including seed development, germination and responses to water-deficit stress. A complex ABA signaling network integrates environmental signals including water availability and light intensity and quality to fine-tune the response to a changing environment. To further define the regulatory pathways that control water-deficit and ABA responses, we carried out a gene-trap tagging screen for water-deficit-regulated genes in Arabidopsis thaliana. This screen identified PLASTID MOVEMENT IMPAIRED1 (PMI1), a gene involved in blue-light-induced chloroplast movement, as functioning in ABA-response pathways. We provide evidence that PMI1 is involved in the regulation of seed germination by ABA, acting upstream of the intersection between ABA and low-glucose signaling pathways. Furthermore, PMI1 participates in the regulation of ABA accumulation during periods of water deficit at the seedling stage. The combined phenotypes of pmi1 mutants in chloroplast movement and ABA responses indicate that ABA signaling may modulate chloroplast motility. This result was further supported by the detection of altered chloroplast movements in the ABA mutants aba1-6, aba2-1 and abi1-1.

  12. Alkaline-stress response in Glycine soja leaf identifies specific transcription factors and ABA-mediated signaling factors.

    PubMed

    Ge, Ying; Li, Yong; Lv, De-Kang; Bai, Xi; Ji, Wei; Cai, Hua; Wang, Ao-Xue; Zhu, Yan-Ming

    2011-06-01

    Transcriptome of Glycine soja leaf tissue during a detailed time course formed a foundation for examining transcriptional processes during NaHCO(3) stress treatment. Of a total of 2,310 detected differentially expressed genes, 1,664 genes were upregulated and 1,704 genes were downregulated at various time points. The number of stress-regulated genes increased dramatically after a 6-h stress treatment. GO category gene enrichment analysis revealed that most of the differentially expressed genes were involved in cell structure, protein synthesis, energy, and secondary metabolism. Another enrichment test revealed that the response of G. soja to NaHCO(3) highlights specific transcription factors, such as the C2C2-CO-like, MYB-related, WRKY, GARP-G2-like, and ZIM families. Co-expressed genes were clustered into ten classes (P < 0.001). Intriguingly, one cluster of 188 genes displayed a unique expression pattern that increases at an early stage (0.5 and 3 h), followed by a decrease from 6 to 12 h. This group was enriched in regulation of transcription components, including AP2-EREBP, bHLH, MYB/MYB-related, C2C2-CO-like, C2C2-DOF, C2C2, C3H, and GARP-G2-like transcription factors. Analysis of the 1-kb upstream regions of transcripts displaying similar changes in abundance identified 19 conserved motifs, potential binding sites for transcription factors. The appearance of ABA-responsive elements in the upstream of co-expression genes reveals that ABA-mediated signaling participates in the signal transduction in alkaline response.

  13. Overexpression of Rosa rugosa anthocyanidin reductase enhances tobacco tolerance to abiotic stress through increased ROS scavenging and modulation of ABA signaling.

    PubMed

    Luo, Ping; Shen, Yuxiao; Jin, Shuangxia; Huang, Shasha; Cheng, Xu; Wang, Zhen; Li, Penghui; Zhao, Jian; Bao, Manzhu; Ning, Guogui

    2016-04-01

    Anthocyanidin reductase (ANR) is a key enzyme involved in the biosynthesis of proanthocyanidins (PAs) and plays a role in the plant stress response. However, the mechanism by which ANR confers stress tolerance in plants is not understood. Here, we report the isolation of RrANR, the homologous gene from rose, and NtABF, an ABA-response related transcription factor gene from tobacco. These genes were characterized regarding their functions in stress responses through the use of transgenic, transcriptomic and physiological analyses. Over-expression of RrANR in tobacco resulted in an increased accumulation of both PAs and abscisic acid (ABA), and also enhanced stress tolerance. Transcriptomic analysis of these transgenic tobacco lines indicated that RrANR overexpression induced global transcriptomic changes, including these involved in oxidation/reduction, hormone response and secondary metabolism. Genes related to ABA biosynthesis and reactive oxygen species (ROS)-scavenging were up-regulated in RrANR transgenic lines, and these effects were phenocopied by the direct treatment of tobacco plants with PAs and ABA. Transcriptomic data from each of these treatments identified the upregulation of a putative NtABF. Furthermore, the up-regulation of NtABF in RrANR transformants or in PAs- and ABA-treated tobacco plants was associated with enhanced stress tolerance. Overexpression of NtABF in transgenic tobacco mimicked the effects of RrANR-transgenic plants with regard to the up-regulation of ROS-scavenging genes and an increase in oxidative tolerance. Taken together, our findings indicate that overexpression of RrANR results in an increase in plant tolerance to oxidative stress via increased scavenging of ROS and modulation of the ABA signaling pathway.

  14. Type B Heterotrimeric G Protein γ-Subunit Regulates Auxin and ABA Signaling in Tomato[OPEN

    PubMed Central

    Subramaniam, Gayathery; Trusov, Yuri; Hayashi, Satomi; Batley, Jacqueline

    2016-01-01

    Heterotrimeric G proteins composed of α, β, and γ subunits are central signal transducers mediating the cellular response to multiple stimuli in most eukaryotes. Gγ subunits provide proper cellular localization and functional specificity to the heterotrimer complex. Plant Gγ subunits, divided into three structurally distinct types, are more diverse than their animal counterparts. Type B Gγ subunits, lacking a carboxyl-terminal isoprenylation motif, are found only in flowering plants. We present the functional characterization of type B Gγ subunit (SlGGB1) in tomato (Solanum lycopersicum). We show that SlGGB1 is the most abundant Gγ subunit in tomato and strongly interacts with the Gβ subunit. Importantly, the green fluorescent protein-SlGGB1 fusion protein as well as the carboxyl-terminal yellow fluorescent protein-SlGGB1/amino-terminal yellow fluorescent protein-Gβ heterodimer were localized in the plasma membrane, nucleus, and cytoplasm. RNA interference-mediated silencing of SlGGB1 resulted in smaller seeds, higher number of lateral roots, and pointy fruits. The silenced lines were hypersensitive to exogenous auxin, while levels of endogenous auxins were lower or similar to those of the wild type. SlGGB1-silenced plants also showed strong hyposensitivity to abscisic acid (ABA) during seed germination but not in other related assays. Transcriptome analysis of the transgenic seeds revealed abnormal expression of genes involved in ABA sensing, signaling, and response. We conclude that the type B Gγ subunit SlGGB1 mediates auxin and ABA signaling in tomato. PMID:26668332

  15. Transcript and hormone analyses reveal the involvement of ABA-signalling, hormone crosstalk and genotype-specific biological processes in cold-shock response in wheat.

    PubMed

    Kalapos, Balázs; Dobrev, Petre; Nagy, Tibor; Vítámvás, Pavel; Györgyey, János; Kocsy, Gábor; Marincs, Ferenc; Galiba, Gábor

    2016-12-01

    The effect of one-day cold-shock on the transcriptome and phytohormones (auxin, cytokinins, abscisic, jasmonic and salicylic acids) was characterised in freezing-sensitive (Chinese Spring), highly freezing-tolerant (Cheyenne) and moderately freezing-tolerant (Chinese Spring substituted with Cheyenne's 5A chromosome) wheat genotypes. Altogether, 636 differentially expressed genes responding to cold-shock were identified. Defence genes encoding LEA proteins, dehydrins, chaperons and other temperature-stress responsive proteins were up-regulated in a genotype-independent manner. Abscisic acid was up-regulated by cold accompanied by adherent expression of its metabolic genes. Data revealed the involvement of particular routes within ABA-dependent signalling in response to cold-shock in the examined genotypes. Cold-shock affected gene expression along carbohydrate metabolic pathways. In photosynthesis, cold-shock changed the expression of a number of genes in the same way as it was previously reported for ABA. Overrepresentation analysis of the differentially expressed genes supported the ABA-signalling and carbohydrate metabolism results, and revealed some pronounced biological process GO categories associated with the cold-shock response of the genotypes. Protein network analysis indicated differences between the genotypes in the information flow along their signal perception and transduction, suggesting different biochemical and cellular strategies in their reaction to cold-shock.

  16. Twenty years of research on Asr (ABA-stress-ripening) genes and proteins.

    PubMed

    González, Rodrigo M; Iusem, Norberto D

    2014-05-01

    Investigating how plants cope with different abiotic stresses-mainly drought and extreme temperatures-is pivotal for both understanding the underlying signaling pathways and improving genetically engineered crops. Plant cells are known to react defensively to mild and severe dehydration by initiating several signal transduction pathways that result in the accumulation of different proteins, sugar molecules and lipophilic anti-oxidants. Among the proteins that build up under these adverse conditions are members of the ancestral ASR (ABA-stress-ripening) family, which is conserved in the plant kingdom but lacks orthologs in Arabidopsis. This review provides a comprehensive summary of the state of the art regarding ASRs, going back to the original description and cloning of the tomato ASR cDNA. That seminal discovery sparked worldwide interest amongst research groups spanning multiple fields: biochemistry, cell biology, evolution, physiology and epigenetics. As these proteins function as both chaperones and transcription factors; this review also covers the progress made on relevant molecular features that account for these dual roles-including the recent identification of their target genes-which may inspire future basic research. In addition, we address reports of drought-tolerant ASR-transgenic plants of different species, highlighting the influential work of authors taking more biotechnological approaches.

  17. SlNCED1 and SlCYP707A2: key genes involved in ABA metabolism during tomato fruit ripening.

    PubMed

    Ji, Kai; Kai, Wenbin; Zhao, Bo; Sun, Yufei; Yuan, Bing; Dai, Shengjie; Li, Qian; Chen, Pei; Wang, Ya; Pei, Yuelin; Wang, Hongqing; Guo, Yangdong; Leng, Ping

    2014-10-01

    Abscisic acid (ABA) plays an important role in fruit development and ripening. Here, three NCED genes encoding 9-cis-epoxycarotenoid dioxygenase (NCED, a key enzyme in the ABA biosynthetic pathway) and three CYP707A genes encoding ABA 8'-hydroxylase (a key enzyme in the oxidative catabolism of ABA) were identified in tomato fruit by tobacco rattle virus-induced gene silencing (VIGS). Quantitative real-time PCR showed that VIGS-treated tomato fruits had significant reductions in target gene transcripts. In SlNCED1-RNAi-treated fruits, ripening slowed down, and the entire fruit turned to orange instead of red as in the control. In comparison, the downregulation of SlCYP707A2 expression in SlCYP707A2-silenced fruit could promote ripening; for example, colouring was quicker than in the control. Silencing SlNCED2/3 or SlCYP707A1/3 made no significant difference to fruit ripening comparing RNAi-treated fruits with control fruits. ABA accumulation and SlNCED1transcript levels in the SlNCED1-RNAi-treated fruit were downregulated to 21% and 19% of those in control fruit, respectively, but upregulated in SlCYP707A2-RNAi-treated fruit. Silencing SlNCED1 or SlCYP707A2 by VIGS significantly altered the transcripts of a set of both ABA-responsive and ripening-related genes, including ABA-signalling genes (PYL1, PP2C1, and SnRK2.2), lycopene-synthesis genes (SlBcyc, SlPSY1 and SlPDS), and cell wall-degrading genes (SlPG1, SlEXP, and SlXET) during ripening. These data indicate that SlNCED1 and SlCYP707A2 are key genes in the regulation of ABA synthesis and catabolism, and are involved in fruit ripening as positive and negative regulators, respectively.

  18. A Direct Link between Abscisic Acid Sensing and the Chromatin-Remodeling ATPase BRAHMA via Core ABA Signaling Pathway Components.

    PubMed

    Peirats-Llobet, Marta; Han, Soon-Ki; Gonzalez-Guzman, Miguel; Jeong, Cheol Woong; Rodriguez, Lesia; Belda-Palazon, Borja; Wagner, Doris; Rodriguez, Pedro L

    2016-01-04

    Optimal response to drought is critical for plant survival and will affect biodiversity and crop performance during climate change. Mitotically heritable epigenetic or dynamic chromatin state changes have been implicated in the plant response to the drought stress hormone abscisic acid (ABA). The Arabidopsis SWI/SNF chromatin-remodeling ATPase BRAHMA (BRM) modulates response to ABA by preventing premature activation of stress response pathways during germination. We show that core ABA signaling pathway components physically interact with BRM and post-translationally modify BRM by phosphorylation/dephosphorylation. Genetic evidence suggests that BRM acts downstream of SnRK2.2/2.3 kinases, and biochemical studies identified phosphorylation sites in the C-terminal region of BRM at SnRK2 target sites that are evolutionarily conserved. Finally, the phosphomimetic BRM(S1760D S1762D) mutant displays ABA hypersensitivity. Prior studies showed that BRM resides at target loci in the ABA pathway in the presence and absence of the stimulus, but is only active in the absence of ABA. Our data suggest that SnRK2-dependent phosphorylation of BRM leads to its inhibition, and PP2CA-mediated dephosphorylation of BRM restores the ability of BRM to repress ABA response. These findings point to the presence of a rapid phosphorylation-based switch to control BRM activity; this property could be potentially harnessed to improve drought tolerance in plants.

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

    PubMed Central

    Gao, Caiqiu; Zhang, Kaimin; Yang, Guiyan; Wang, Yucheng

    2012-01-01

    Peroxiredoxins (Prxs) are a recently discovered family of antioxidant enzymes that catalyze the reduction of peroxides and alkyl peroxides. In this study, four Prx genes (named as ThPrxII, ThPrxIIE, ThPrxIIF, and Th2CysPrx) were cloned from Tamarix hispida. Their expression profiles in response to stimulus of NaCl, NaHCO3, PEG, CdCl2 and abscisic acid (ABA) in roots, stems and leaves of T. hispida were investigated using real-time RT-PCR. The results showed that the four ThPrxs were all expressed in roots, stems and leaves. Furthermore, the transcript levels of ThPrxIIE and ThPrxII were the lowest and the highest, respectively, in all tissue types. All the ThPrx genes were induced by both NaCl and NaHCO3 and reached their highest expression levels at the onset of stress in roots. Under PEG and CdCl2 stress, the expression patterns of these ThPrxs showed temporal and spatial specificity. The expressions of the ThPrxs were all differentially regulated by ABA, indicating that they are all involved in the ABA signaling pathway. These findings reveal a complex regulation of Prxs that is dependent on the type of Prx, tissue, and the signaling molecule. The divergence of the stress-dependent transcriptional regulation of the ThPrx gene family in T. hispida may provide an essential basis for the elucidation of Prx function in future work. PMID:22489180

  20. Expression analysis of four peroxiredoxin genes from Tamarix hispida in response to different abiotic stresses and Exogenous Abscisic Acid (ABA).

    PubMed

    Gao, Caiqiu; Zhang, Kaimin; Yang, Guiyan; Wang, Yucheng

    2012-01-01

    Peroxiredoxins (Prxs) are a recently discovered family of antioxidant enzymes that catalyze the reduction of peroxides and alkyl peroxides. In this study, four Prx genes (named as ThPrxII, ThPrxIIE, ThPrxIIF, and Th2CysPrx) were cloned from Tamarix hispida. Their expression profiles in response to stimulus of NaCl, NaHCO(3), PEG, CdCl(2) and abscisic acid (ABA) in roots, stems and leaves of T. hispida were investigated using real-time RT-PCR. The results showed that the four ThPrxs were all expressed in roots, stems and leaves. Furthermore, the transcript levels of ThPrxIIE and ThPrxII were the lowest and the highest, respectively, in all tissue types. All the ThPrx genes were induced by both NaCl and NaHCO(3) and reached their highest expression levels at the onset of stress in roots. Under PEG and CdCl(2) stress, the expression patterns of these ThPrxs showed temporal and spatial specificity. The expressions of the ThPrxs were all differentially regulated by ABA, indicating that they are all involved in the ABA signaling pathway. These findings reveal a complex regulation of Prxs that is dependent on the type of Prx, tissue, and the signaling molecule. The divergence of the stress-dependent transcriptional regulation of the ThPrx gene family in T. hispida may provide an essential basis for the elucidation of Prx function in future work.

  1. Grape hexokinases are involved in the expression regulation of sucrose synthase- and cell wall invertase-encoding genes by glucose and ABA.

    PubMed

    Wang, Xiu-Qin; Zheng, Li-Li; Lin, Hao; Yu, Fei; Sun, Li-Hui; Li, Li-Mei

    2017-02-28

    Hexokinase (HXK, EC 2.7.1.1) is a multifunctional protein that both is involved in catalyzing the first step of glycolysis and plays an important role in sugar signaling. However, the supporting genetic evidence on hexokinases (CsHXKs) from grape (Vitis vinifera L. cv. Cabernet Sauvignon) berries has been lacking. Here, to investigate the role of CsHXK isoforms as glucose (Glc) and abscisic acid (ABA) sensors, we cloned two hexokinase isozymes, CsHXK1 and CsHXK2 with highly conserved genomic structure of nine exons and eight introns. We also found adenosine phosphate binding, substrate recognition and connection sites in their putative proteins. During grape berry development, the expression profiles of two CsHXK isoforms, sucrose synthases (SuSys) and cell wall invertase (CWINV) genes increased concomitantly with high levels of endogenous Glc and ABA. Furthermore, we showed that in wild type grape berry calli (WT), glucose repressed the expression levels of sucrose synthase (SuSy) and cell wall invertase (CWINV) genes, while ABA increased their expression levels. ABA could not only effectively improve the expression levels of SuSy and CWINV, but also block the repression induced by glucose on the expression of both genes. However, after silencing CsHXK1 or CsHXK2 in grape calli, SuSy and CWINV expression were enhanced, and the expressions of the two genes are insensitive in response to Glc treatment. Interestingly, exogenous ABA alone could not or less increase SuSy and CWINV expression in silencing CsHXK1 or CsHXK2 grape calli compared to WT. Meantime, ABA could not block the repression induced by glucose on the expression of SuSy and CWINV in CsHXK1 or CsHXK2 mutants. Therefore, Glc signal transduction depends on the regulation of CsHXK1 or CsHXK2. ABA signal was also disturbed by CsHXK1 or CsHXK2 silencing. The present results provide new insights into the regulatory role of Glc and ABA on the enzymes related to sugar metabolism in grape berry.

  2. Abscisic acid (ABA) inhibits light-induced stomatal opening through calcium- and nitric oxide-mediated signaling pathways.

    PubMed

    Garcia-Mata, Carlos; Lamattina, Lorenzo

    2007-01-01

    Nitric oxide (NO) is an important signaling component of ABA-induced stomatal closure. However, only fragmentary data are available about NO effect on the inhibition of stomatal opening. Here, we present results supporting that, in Vicia faba guard cells, there is a critical Ca2+-dependent NO increase required for the ABA-mediated inhibition of stomatal opening. Light-induced stomatal opening was inhibited by exogenous NO in V. faba epidermal strips. Furthermore, ABA-mediated inhibition of stomatal opening was blocked by the specific NO scavenger cPTIO, supporting the involvement of endogenous NO in this process. Since the raise in Ca2+ concentration is a pre-requisite in ABA-mediated inhibition of stomatal opening, it was interesting to establish how does Ca2+, NO and ABA interact in the inhibition of light-induced stomatal opening. The permeable Ca2+ specific buffer BAPTA-AM blocked both ABA- and Ca2+- but not NO-mediated inhibition of stomatal opening. The NO synthase (NOS) specific inhibitor L-NAME prevented Ca2+-mediated inhibition of stomatal opening, indicating that a NOS-like activity was required for Ca2+ signaling. Furthermore, experiments using the NO specific fluorescent probe DAF-2DA indicated that Ca2+ induces an increase of endogenous NO. These results indicate that, in addition to the roles in ABA-triggered stomatal closure, both NO and Ca2+ are active components of signaling events acting in ABA inhibition of light-induced stomatal opening. Results also support that Ca2+ induces the NO production through the activation of a NOS-like activity.

  3. Salt tolerance in soybean WF-7 is partially regulated by ABA and ROS signaling and involves withholding toxic Cl- ions from aerial tissues.

    PubMed

    Ren, Shuxin; Weeda, Sarah; Li, Haiwen; Whitehead, Brodie; Guo, Yangdong; Atalay, Asmare; Parry, John

    2012-08-01

    Salt tolerance in plants is a complex trait involving multiple mechanisms. Understanding these mechanisms and their regulation will assist in developing novel strategies to engineer salt-tolerant crops. In the current study, we investigated salt-tolerant mechanisms in soybean (Glycine max) cultivar WF-7 in comparison to salt-sensitive Union. In vivo and in vitro salt assays demonstrated the salt tolerance of WF-7 at the seedling stage and during germination. After a 10-day 200 mM NaCl treatment, chlorophyll content in Union was reduced by 50 % compared to a 17 % reduction in WF-7. WF-7 was also less affected by abscisic acid (ABA) and NaCl during germination than Union. Upon ABA and NaCl treatment, the ABA-responsive genes SCOF1, ASN1, bZIP44, and AAPK1 are differentially expressed in WF-7 and Union seedlings. These results suggest that salt tolerance in WF-7 is in part regulated through an ABA-dependent pathway. In addition, following a 4-day 200 mM NaCl treatment, WF-7 produced more H₂O₂ than Union indicating the involvement of reactive oxygen species (ROS) in regulating salt tolerance in WF-7. Yet another mechanism WF-7 employs is withholding toxic chloride (Cl⁻) ions from aerial tissues. Following 200 mM NaCl treatment, Cl⁻ accumulation was mostly localized to the roots of WF-7. In contrast, most of the Cl⁻ in Union was transported into the stems and leaves. Taken together, our results demonstrated a role of ABA and ROS in regulating salt tolerance in WF-7, and the critical role of Cl⁻ in NaCl-induced mortality in soybean. Key message Withholding toxic Cl⁻ ions from leaves and, to a lesser extent, stems, confers salt tolerance to soybean WF-7. In addition, ABA and ROS may be involved in salt-stress signal transduction.

  4. H2O2 and ABA signaling are responsible for the increased Na+ efflux and water uptake in Gossypium hirsutum L. roots in the non-saline side under non-uniform root zone salinity.

    PubMed

    Kong, Xiangqiang; Luo, Zhen; Dong, Hezhong; Eneji, A Egrinya; Li, Weijiang

    2016-04-01

    Non-uniform root salinity increases the Na(+)efflux, water use, and growth of the root in non-saline side, which may be regulated by some form of signaling induced by the high-salinity side. However, the signaling and its specific function have remained unknown. Using a split-root system to simulate a non-uniform root zone salinity in Gossypium hirsutum L., we showed that the up-regulated expression of sodium efflux-related genes (SOS1, SOS2, PMA1, and PMA2) and water uptake-related genes (PIP1 and PIP2) was possibly involved in the elevated Na(+) efflux and water use in the the roots in the non-saline side. The increased level of indole acetic acid (IAA) in the non-saline side was the likely cause of the increased root growth. Also, the abscisic acid (ABA) and H2O2 contents in roots in the non-saline side increased, possibly due to the increased expression of their key biosynthesis genes, NCED and RBOHC, and the decreased expression of ABA catabolic CYP707A genes. Exogenous ABA added to the non-saline side induced H2O2 generation by up-regulating the RBOHC gene, but this was decreased by exogenous fluridone. Exogenous H2O2 added to the non-saline side reduced the ABA content by down-regulating NCED genes, which can be induced by diphenylene iodonium (DPI) treatment in the non-saline side, suggesting a feedback mechanism between ABA and H2O2.Both exogenous ABA and H2O2 enhanced the expression of SOS1, PIP1;7 ,PIP2;2, and PIP2;10 genes, but these were down-regulated by fluridone and DPI, suggesting that H2O2 and ABA are important signals for increasing root Na(+) efflux and water uptake in the roots in the non-saline side.

  5. Brassinosteroids modulate ABA-induced stomatal closure in Arabidopsis

    PubMed Central

    Ha, Yunmi; Shang, Yun; Nam, Kyoung Hee

    2016-01-01

    Stomatal movement in response to water availability is an important physiological process in the survival of land plants. The plant hormone abscisic acid (ABA) and brassinosteroids (BRs) regulate stomatal closure. The physiological functions of ABA and BRs, including germination, cell elongation and stomatal movement, are generally known to be antagonistic. Here, we investigated how BRs affect stomatal movement alone and in combination with ABA. We demonstrate that brassinoslide (BL), the most active BR, promotes stomatal closure in an ABA-independent manner. Interestingly, BL also inhibited ABA-induced stomatal closure when a high concentration of BL was added to ABA. Furthermore, we found that the induction of some genes for reactive oxygen species (ROS) generation by ABA (AtrbohD, NIA1 and NIA2) and subsequent ROS production were repressed by BL treatment. The BR signaling mutant bri1-301 failed to inhibit ABA-induced stomatal closure upon BL treatment. However, BRI1-overexpressing transgenic plants were hypersensitive to ABA during stomatal closure, and BL reversed ABA-induced stomatal closure more completely than in wild type plants. Taken together, these results suggest that BRs can positively and negatively modulate ABA-induced stomatal closure. Therefore, interactions between ABA and BR signaling are important for the regulation of stomatal closure. PMID:27856707

  6. Electrical signaling, stomatal conductance, ABA and ethylene content in avocado trees in response to root hypoxia.

    PubMed

    Gil, Pilar M; Gurovich, Luis; Schaffer, Bruce; García, Nicolás; Iturriaga, Rodrigo

    2009-02-01

    Avocado (Persea americana Mill.) trees are among the most sensitive of fruit tree species to root hypoxia as a result of flooded or poorly drained soil. Similar to drought stress, an early physiological response to root hypoxia in avocado is a reduction of stomatal conductance. It has been previously determined in avocado trees that an extracellular electrical signal between the base of stem and leaves is produced and related to reductions in stomatal conductance in response to drought stress. The current study was designed to determine if changes in the extracellular electrical potential between the base of the stem and leaves in avocado trees could also be detected in response to short-term (min) or long-term (days) root hypoxia, and if these signals could be related to stomatal conductance (gs), root and leaf ABA and ACC concentrations, ethylene emission from leaves and leaf abscission. In contrast to previous observations for drought-stressed trees, short-term or long-term root hypoxia did not stimulate an electrical potential difference between the base of the stem and leaves. Short-term hypoxia did not result in a significant decrease in gs compared with plants in the control treatment, and no differences in ABA concentration were found between plants subjected to hypoxia and control plants. Long-term hypoxia in the root zone resulted in a significant decrease in gs, increased leaf ethylene and increased leaf abscission. The results indicate that for avocado trees exposed to root hypoxia, electrical signals do not appear to be the primary root-to-shoot communication mechanism involved in signaling for stomatal closure as a result of hypoxia in the root zone.

  7. Electrical signaling, stomatal conductance, ABA and Ethylene content in avocado trees in response to root hypoxia

    PubMed Central

    Gurovich, Luis; Schaffer, Bruce; García, Nicolás; Iturriaga, Rodrigo

    2009-01-01

    Avocado (Persea americana Mill.) trees are among the most sensitive of fruit tree species to root hypoxia as a result of flooded or poorly drained soil. Similar to drought stress, an early physiological response to root hypoxia in avocado is a reduction of stomatal conductance. It has been previously determined in avocado trees that an extracellular electrical signal between the base of stem and leaves is produced and related to reductions in stomatal conductance in response to drought stress. The current study was designed to determine if changes in the extracellular electrical potential between the base of the stem and leaves in avocado trees could also be detected in response to short-term (min) or long-term (days) root hypoxia, and if these signals could be related to stomatal conductance (gs), root and leaf ABA and ACC concentrations, ethylene emission from leaves and leaf abscission. In contrast to previous observations for drought-stressed trees, short-term or long-term root hypoxia did not stimulate an electrical potential difference between the base of the stem and leaves. Short-term hypoxia did not result in a significant decrease in gs compared with plants in the control treatment, and no differences in ABA concentration were found between plants subjected to hypoxia and control plants. Long-term hypoxia in the root zone resulted in a significant decrease in gs, increased leaf ethylene and increased leaf abscission. The results indicate that for avocado trees exposed to root hypoxia, electrical signals do not appear to be the primary root-to-shoot communication mechanism involved in signaling for stomatal closure as a result of hypoxia in the root zone. PMID:19649181

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

    PubMed

    Li, Zixing; Waadt, Rainer; Schroeder, Julian I

    2016-05-01

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

  9. ABA signaling is necessary but not sufficient for RD29B transcriptional memory during successive dehydration stresses in Arabidopsis thaliana.

    PubMed

    Virlouvet, Laetitia; Ding, Yong; Fujii, Hiroaki; Avramova, Zoya; Fromm, Michael

    2014-07-01

    Plants subjected to a prior dehydration stress were seen to have altered transcriptional responses during a subsequent dehydration stress for up to 5 days after the initial stress. The abscisic acid (ABA) inducible RD29B gene of Arabidopsis thaliana was strongly induced after the first stress and displayed transcriptional memory with transcript levels nine-fold higher during the second dehydration stress. These increased transcript levels were due to an increased rate of transcription and are associated with an altered chromatin template during the recovery interval between the dehydration stresses. Here we use a combination of promoter deletion/substitutions, mutants in the trans-acting transcription factors and their upstream protein kinases, and treatments with exogenous ABA or dehydration stress to advance our understanding of the features required for transcriptional memory of RD29B. ABA Response Elements (ABREs) are sufficient to confer transcriptional memory on a minimal promoter, although there is a context effect from flanking sequences. Different mutations in Snf1 Related Protein Kinase 2 (SnRK2) genes positively and negatively affected the response, suggesting that this effect is important for transcriptional memory. Although exogenous ABA treatments could prime transcriptional memory, a second ABA treatment was not sufficient to activate transcriptional memory. Therefore, we concluded that transcriptional memory requires ABA and an ABA-independent factor that is induced or activated by a subsequent dehydration stress and directly or indirectly results in a more active RD29B chromatin template. These results advance our knowledge of the cis- and trans-acting factors that are required for transcriptional memory of RD29B.

  10. An ABA-responsive DRE-binding protein gene from Setaria italica, SiARDP, the target gene of SiAREB, plays a critical role under drought stress.

    PubMed

    Li, Cong; Yue, Jing; Wu, Xiaowei; Xu, Cong; Yu, Jingjuan

    2014-10-01

    The DREB (dehydration-responsive element binding)-type transcription factors regulate the expression of stress-inducible genes by binding the DRE/CRT cis-elements in promoter regions. The upstream transcription factors that regulate the transcription of DREB transcription factors have not been clearly defined, although the function of DREB transcription factors in abiotic stress is known. In this study, an abscisic acid (ABA)-responsive DREB-binding protein gene (SiARDP) was cloned from foxtail millet (Setaria italica). The transcript level of SiARDP increased not only after drought, high salt, and low temperature stresses, but also after an ABA treatment in foxtail millet seedlings. Two ABA-responsive elements (ABRE1: ACGTGTC; ABRE2: ACGTGGC) exist in the promoter of SiARDP. Further analyses showed that two ABA-responsive element binding (AREB)-type transcription factors, SiAREB1 and SiAREB2, could physically bind to the ABRE core element in vitro and in vivo. The constitutive expression of SiARDP in Arabidopsis thaliana enhanced drought and salt tolerance during seed germination and seedling development, and overexpression of SiARDP in foxtail millet improved drought tolerance. The expression levels of target genes of SiARDP were upregulated in transgenic Arabidopsis and foxtail millet. These results reveal that SiARDP, one of the target genes of SiAREB, is involved in ABA-dependent signal pathways and plays a critical role in the abiotic stress response in plants.

  11. Characterization of potential ABA receptors in Vitis vinifera.

    PubMed

    Boneh, Uri; Biton, Iris; Zheng, Chuanlin; Schwartz, Amnon; Ben-Ari, Giora

    2012-02-01

    Molecular control mechanisms for abiotic stress tolerance are based on the activation and regulation of specific stress-related genes. The phytohormone abscisic acid (ABA) is a key endogenous messenger in a plant's response to such stresses. A novel ABA binding mechanism which plays a key role in plant cell signaling cascades has recently been uncovered. In the absence of ABA, a type 2C protein phosphatase (PP2C) interacts and inhibits the kinase SnRK2. Binding of ABA to the PYR/PYLs receptors enables interaction between the ABA receptor and the PP2C protein, and abrogates the SnRK2 inactivation. The active SnRK2 is then free to activate the ABA-responsive element Binding Factors which target ABA-dependent gene expression. We used the grape as a model to study the ABA perception mechanism in fruit trees. The grape ABA signaling cascade consists of at least seven ABA receptors and six PP2Cs. We used a yeast two-hybrid system to examine physical interaction in vitro between the grape ABA receptors and their interacting partners, and found that twenty-two receptor-PP2C interactions can occur. Moreover, quantifying these affinities by the use of the LacZ reporter enables us to show that VvPP2C4 and VvPP2C9 are the major binding partners of the ABA receptor. We also tested in vivo the root and leaf gene expression of the various ABA receptors and PP2Cs in the presence of exogenic ABA and under different abiotic stresses such as high salt concentration, cold and drought, and found that many of these genes are regulated by such abiotic environmental factors. Our results indicate organ specificity in the ABA receptor genes and stress specificity in the VvPP2Cs. We suggest that VvPP2C4 is the major PP2C involved in ABA perception in leaves and roots, and VvRCAR6 and VvRCAR5 respectively, are the major receptors involved in ABA perception in these organs. Identification, characterization and manipulation of the central players in the ABA signaling cascades in fruit trees is

  12. Quantitative Proteomic Analyses Identify ABA-Related Proteins and Signal Pathways in Maize Leaves under Drought Conditions.

    PubMed

    Zhao, Yulong; Wang, Yankai; Yang, Hao; Wang, Wei; Wu, Jianyu; Hu, Xiuli

    2016-01-01

    Drought stress is one of major factors resulting in maize yield loss. The roles of abscisic acid (ABA) have been widely studied in crops in response to drought stress. However, more attention is needed to identify key ABA-related proteins and also gain deeper molecular insights about drought stress in maize. Based on this need, the physiology and proteomics of the ABA-deficient maize mutant vp5 and its wild-type Vp5 under drought stress were examined and analyzed. Malondialdehyde content increased and quantum efficiency of photosystem II decreased under drought stress in both genotypes. However, the magnitude of the increase or decrease was significantly higher in vp5 than in Vp5. A total of 7051 proteins with overlapping expression patterns among three replicates in the two genotypes were identified by Multiplex run iTRAQ-based quantitative proteomic and liquid chromatography-tandem mass spectrometry methods, of which the expression of only 150 proteins (130 in Vp5, 27 in vp5) showed changes of at least 1.5-fold under drought stress. Among the 150 proteins, 67 and 60 proteins were up-regulated and down-regulated by drought stress in an ABA-dependent way, respectively. ABA was found to play active roles in regulating signaling pathways related to photosynthesis, oxidative phosphorylation (mainly related to ATP synthesis), and glutathione metabolism (involved in antioxidative reaction) in the maize response to drought stress. Our results provide an extensive dataset of ABA-dependent, drought-regulated proteins in maize plants, which may help to elucidate the underlying mechanisms of ABA-enhanced tolerance to drought stress in maize.

  13. Quantitative Proteomic Analyses Identify ABA-Related Proteins and Signal Pathways in Maize Leaves under Drought Conditions

    PubMed Central

    Zhao, Yulong; Wang, Yankai; Yang, Hao; Wang, Wei; Wu, Jianyu; Hu, Xiuli

    2016-01-01

    Drought stress is one of major factors resulting in maize yield loss. The roles of abscisic acid (ABA) have been widely studied in crops in response to drought stress. However, more attention is needed to identify key ABA-related proteins and also gain deeper molecular insights about drought stress in maize. Based on this need, the physiology and proteomics of the ABA-deficient maize mutant vp5 and its wild-type Vp5 under drought stress were examined and analyzed. Malondialdehyde content increased and quantum efficiency of photosystem II decreased under drought stress in both genotypes. However, the magnitude of the increase or decrease was significantly higher in vp5 than in Vp5. A total of 7051 proteins with overlapping expression patterns among three replicates in the two genotypes were identified by Multiplex run iTRAQ-based quantitative proteomic and liquid chromatography-tandem mass spectrometry methods, of which the expression of only 150 proteins (130 in Vp5, 27 in vp5) showed changes of at least 1.5-fold under drought stress. Among the 150 proteins, 67 and 60 proteins were up-regulated and down-regulated by drought stress in an ABA-dependent way, respectively. ABA was found to play active roles in regulating signaling pathways related to photosynthesis, oxidative phosphorylation (mainly related to ATP synthesis), and glutathione metabolism (involved in antioxidative reaction) in the maize response to drought stress. Our results provide an extensive dataset of ABA-dependent, drought-regulated proteins in maize plants, which may help to elucidate the underlying mechanisms of ABA-enhanced tolerance to drought stress in maize. PMID:28008332

  14. Function of the HD-Zip I gene Oshox22 in ABA-mediated drought and salt tolerances in rice.

    PubMed

    Zhang, Shuxin; Haider, Imran; Kohlen, Wouter; Jiang, Li; Bouwmeester, Harro; Meijer, Annemarie H; Schluepmann, Henriette; Liu, Chun-Ming; Ouwerkerk, Pieter B F

    2012-12-01

    Oshox22 belongs to the homeodomain-leucine zipper (HD-Zip) family I of transcription factors, most of which have unknown functions. Here we show that the expression of Oshox22 is strongly induced by salt stress, abscisic acid (ABA), and polyethylene glycol treatment (PEG), and weakly by cold stress. Trans-activation assays in yeast and transient expression analyses in rice protoplasts demonstrated that Oshox22 is able to bind the CAAT(G/C)ATTG element and acts as a transcriptional activator that requires both the HD and Zip domains. Rice plants homozygous for a T-DNA insertion in the promoter region of Oshox22 showed reduced Oshox22 expression and ABA content, decreased sensitivity to ABA, and enhanced tolerance to drought and salt stresses at the seedling stage. In contrast, transgenic rice over-expressing Oshox22 showed increased sensitivity to ABA, increased ABA content, and decreased drought and salt tolerances. Based on these results, we conclude that Oshox22 affects ABA biosynthesis and regulates drought and salt responses through ABA-mediated signal transduction pathways.

  15. Molecular identification of zeaxanthin epoxidase of Nicotiana plumbaginifolia, a gene involved in abscisic acid biosynthesis and corresponding to the ABA locus of Arabidopsis thaliana.

    PubMed Central

    Marin, E; Nussaume, L; Quesada, A; Gonneau, M; Sotta, B; Hugueney, P; Frey, A; Marion-Poll, A

    1996-01-01

    Abscisic acid (ABA) is a plant hormone which plays an important role in seed development and dormancy and in plant response to environmental stresses. An ABA-deficient mutant of Nicotiana plumbaginifolia, aba2, was isolated by transposon tagging using the maize Activator transposon. The aba2 mutant exhibits precocious seed germination and a severe wilty phenotype. The mutant is impaired in the first step of the ABA biosynthesis pathway, the zeaxanthin epoxidation reaction. ABA2 cDNA is able to complement N.plumbaginifolia aba2 and Arabidopsis thaliana aba mutations indicating that these mutants are homologous. ABA2 cDNA encodes a chloroplast-imported protein of 72.5 kDa, sharing similarities with different mono-oxigenases and oxidases of bacterial origin and having an ADP-binding fold and an FAD-binding domain. ABA2 protein, produced in Escherichia coli, exhibits in vitro zeaxanthin epoxidase activity. This is the first report of the isolation of a gene of the ABA biosynthetic pathway. The molecular identification of ABA2 opens the possibility to study the regulation of ABA biosynthesis and its cellular location. Images PMID:8665840

  16. An ABA-mimicking ligand that reduces water loss and promotes drought resistance in plants

    PubMed Central

    Cao, Minjie; Liu, Xue; Zhang, Yan; Xue, Xiaoqian; Zhou, X Edward; Melcher, Karsten; Gao, Pan; Wang, Fuxing; Zeng, Liang; Zhao, Yang; Zhao, Yang; Deng, Pan; Zhong, Dafang; Zhu, Jian-Kang; Xu, H Eric; Xu, Yong

    2013-01-01

    Abscisic acid (ABA) is the most important hormone for plants to resist drought and other abiotic stresses. ABA binds directly to the PYR/PYL family of ABA receptors, resulting in inhibition of type 2C phosphatases (PP2C) and activation of downstream ABA signaling. It is envisioned that intervention of ABA signaling by small molecules could help plants to overcome abiotic stresses such as drought, cold and soil salinity. However, chemical instability and rapid catabolism by plant enzymes limit the practical application of ABA itself. Here we report the identification of a small molecule ABA mimic (AM1) that acts as a potent activator of multiple members of the family of ABA receptors. In Arabidopsis, AM1 activates a gene network that is highly similar to that induced by ABA. Treatments with AM1 inhibit seed germination, prevent leaf water loss, and promote drought resistance. We solved the crystal structure of AM1 in complex with the PYL2 ABA receptor and the HAB1 PP2C, which revealed that AM1 mediates a gate-latch-lock interacting network, a structural feature that is conserved in the ABA-bound receptor/PP2C complex. Together, these results demonstrate that a single small molecule ABA mimic can activate multiple ABA receptors and protect plants from water loss and drought stress. Moreover, the AM1 complex crystal structure provides a structural basis for designing the next generation of ABA-mimicking small molecules. PMID:23835477

  17. Expression of ABA Metabolism-Related Genes Suggests Similarities and Differences Between Seed Dormancy and Bud Dormancy of Peach (Prunus persica)

    PubMed Central

    Wang, Dongling; Gao, Zhenzhen; Du, Peiyong; Xiao, Wei; Tan, Qiuping; Chen, Xiude; Li, Ling; Gao, Dongsheng

    2016-01-01

    Dormancy inhibits seed and bud growth of perennial plants until the environmental conditions are optimal for survival. Previous studies indicated that certain co-regulation pathways exist in seed and bud dormancy. In our study, we found that seed and bud dormancy are similar to some extent but show different reactions to chemical treatments that induce breaking of dormancy. Whether the abscisic acid (ABA) regulatory networks are similar in dormant peach seeds and buds is not well known; however, ABA is generally believed to play a critical role in seed and bud dormancy. In peach, some genes putatively involved in ABA synthesis and catabolism were identified and their expression patterns were studied to learn more about ABA homeostasis and the possible crosstalk between bud dormancy and seed dormancy mechanisms. The analysis demonstrated that two 9-cis-epoxycarotenoid dioxygenase-encoding genes seem to be key in regulating ABA biosynthesis to induce seed and bud dormancy. Three CYP707As play an overlapping role in controlling ABA inactivation, resulting in dormancy-release. In addition, Transcript analysis of ABA metabolism-related genes was much similar demonstrated that ABA pathways was similar in the regulation of vegetative and flower bud dormancy, whereas, expression patterns of ABA metabolism-related genes were different in seed dormancy showed that ABA pathway maybe different in regulating seed dormancy in peach. PMID:26793222

  18. Expression of ABA Metabolism-Related Genes Suggests Similarities and Differences Between Seed Dormancy and Bud Dormancy of Peach (Prunus persica).

    PubMed

    Wang, Dongling; Gao, Zhenzhen; Du, Peiyong; Xiao, Wei; Tan, Qiuping; Chen, Xiude; Li, Ling; Gao, Dongsheng

    2015-01-01

    Dormancy inhibits seed and bud growth of perennial plants until the environmental conditions are optimal for survival. Previous studies indicated that certain co-regulation pathways exist in seed and bud dormancy. In our study, we found that seed and bud dormancy are similar to some extent but show different reactions to chemical treatments that induce breaking of dormancy. Whether the abscisic acid (ABA) regulatory networks are similar in dormant peach seeds and buds is not well known; however, ABA is generally believed to play a critical role in seed and bud dormancy. In peach, some genes putatively involved in ABA synthesis and catabolism were identified and their expression patterns were studied to learn more about ABA homeostasis and the possible crosstalk between bud dormancy and seed dormancy mechanisms. The analysis demonstrated that two 9-cis-epoxycarotenoid dioxygenase-encoding genes seem to be key in regulating ABA biosynthesis to induce seed and bud dormancy. Three CYP707As play an overlapping role in controlling ABA inactivation, resulting in dormancy-release. In addition, Transcript analysis of ABA metabolism-related genes was much similar demonstrated that ABA pathways was similar in the regulation of vegetative and flower bud dormancy, whereas, expression patterns of ABA metabolism-related genes were different in seed dormancy showed that ABA pathway maybe different in regulating seed dormancy in peach.

  19. Inspection of the Grapevine BURP Superfamily Highlights an Expansion of RD22 Genes with Distinctive Expression Features in Berry Development and ABA-Mediated Stress Responses

    PubMed Central

    Matus, José Tomás; Aquea, Felipe; Espinoza, Carmen; Vega, Andrea; Cavallini, Erika; Santo, Silvia Dal; Cañón, Paola; de la Guardia, Amparo Rodríguez-Hoces; Serrano, Jennifer; Tornielli, Giovanni Battista; Arce-Johnson, Patricio

    2014-01-01

    The RESPONSIVE TO DEHYDRATION 22 (RD22) gene is a molecular link between abscisic acid (ABA) signalling and abiotic stress responses. Its expression has been used as a reliable ABA early response marker. In Arabidopsis, the single copy RD22 gene possesses a BURP domain also located at the C-terminus of USP embryonic proteins and the beta subunit of polygalacturonases. In grapevine, a RD22 gene has been identified but putative paralogs are also found in the grape genome, possibly forming a large RD22 family in this species. In this work, we searched for annotations containing BURP domains in the Vitis vinifera genome. Nineteen proteins were defined by a comparative analysis between the two genome predictions and RNA-Seq data. These sequences were compared to other plant BURPs identified in previous genome surveys allowing us to reconceive group classifications based on phylogenetic relationships and protein motif occurrence. We observed a lineage-specific evolution of the RD22 family, with the biggest expansion in grapevine and poplar. In contrast, rice, sorghum and maize presented highly expanded monocot-specific groups. The Vitis RD22 group may have expanded from segmental duplications as most of its members are confined to a region in chromosome 4. The inspection of transcriptomic data revealed variable expression of BURP genes in vegetative and reproductive organs. Many genes were induced in specific tissues or by abiotic and biotic stresses. Three RD22 genes were further studied showing that they responded oppositely to ABA and to stress conditions. Our results show that the inclusion of RNA-Seq data is essential while describing gene families and improving gene annotations. Robust phylogenetic analyses including all BURP members from other sequenced species helped us redefine previous relationships that were erroneously established. This work provides additional evidence for RD22 genes serving as marker genes for different organs or stresses in grapevine. PMID

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

    SciTech Connect

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

    2014-10-02

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

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

    PubMed Central

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

    2011-01-01

    Abscisic acid (ABA) is an essential hormone that controls plant growth, development, and responses to abiotic stresses. Central for ABA signaling is the ABA-mediated autoactivation of three monomeric Snf1-related kinases (SnRK2.2, -2.3, and -2.6). In the absence of ABA, SnRK2s are kept in an inactive state by forming physical complexes with type 2C protein phosphatases (PP2Cs). Upon relief of this inhibition, SnRK2 kinases can autoactivate through unknown mechanisms. Here, we report the crystal structures of full-length Arabidopsis thaliana SnRK2.3 and SnRK2.6 at 1.9- and 2.3-Å resolution, respectively. The structures, in combination with biochemical studies, reveal a two-step mechanism of intramolecular kinase activation that resembles the intermolecular activation of cyclin-dependent kinases. First, release of inhibition by PP2C allows the SnRK2s to become partially active because of an intramolecular stabilization of the catalytic domain by a conserved helix in the kinase regulatory domain. This stabilization enables SnRK2s to gain full activity by activation loop autophosphorylation. Autophosphorylation is more efficient in SnRK2.6, which has higher stability than SnRK2.3 and has well-structured activation loop phosphate acceptor sites that are positioned next to the catalytic site. Together, these data provide a structural framework that links ABA-mediated release of PP2C inhibition to activation of SnRK2 kinases. PMID:22160701

  2. RNA-Seq and Gene Network Analysis Uncover Activation of an ABA-Dependent Signalosome During the Cork Oak Root Response to Drought.

    PubMed

    Magalhães, Alexandre P; Verde, Nuno; Reis, Francisca; Martins, Inês; Costa, Daniela; Lino-Neto, Teresa; Castro, Pedro H; Tavares, Rui M; Azevedo, Herlânder

    2015-01-01

    Quercus suber (cork oak) is a West Mediterranean species of key economic interest, being extensively explored for its ability to generate cork. Like other Mediterranean plants, Q. suber is significantly threatened by climatic changes, imposing the need to quickly understand its physiological and molecular adaptability to drought stress imposition. In the present report, we uncovered the differential transcriptome of Q. suber roots exposed to long-term drought, using an RNA-Seq approach. 454-sequencing reads were used to de novo assemble a reference transcriptome, and mapping of reads allowed the identification of 546 differentially expressed unigenes. These were enriched in both effector genes (e.g., LEA, chaperones, transporters) as well as regulatory genes, including transcription factors (TFs) belonging to various different classes, and genes associated with protein turnover. To further extend functional characterization, we identified the orthologs of differentially expressed unigenes in the model species Arabidopsis thaliana, which then allowed us to perform in silico functional inference, including gene network analysis for protein function, protein subcellular localization and gene co-expression, and in silico enrichment analysis for TFs and cis-elements. Results indicated the existence of extensive transcriptional regulatory events, including activation of ABA-responsive genes and ABF-dependent signaling. We were then able to establish that a core ABA-signaling pathway involving PP2C-SnRK2-ABF components was induced in stressed Q. suber roots, identifying a key mechanism in this species' response to drought.

  3. RNA-Seq and Gene Network Analysis Uncover Activation of an ABA-Dependent Signalosome During the Cork Oak Root Response to Drought

    PubMed Central

    Magalhães, Alexandre P.; Verde, Nuno; Reis, Francisca; Martins, Inês; Costa, Daniela; Lino-Neto, Teresa; Castro, Pedro H.; Tavares, Rui M.; Azevedo, Herlânder

    2016-01-01

    Quercus suber (cork oak) is a West Mediterranean species of key economic interest, being extensively explored for its ability to generate cork. Like other Mediterranean plants, Q. suber is significantly threatened by climatic changes, imposing the need to quickly understand its physiological and molecular adaptability to drought stress imposition. In the present report, we uncovered the differential transcriptome of Q. suber roots exposed to long-term drought, using an RNA-Seq approach. 454-sequencing reads were used to de novo assemble a reference transcriptome, and mapping of reads allowed the identification of 546 differentially expressed unigenes. These were enriched in both effector genes (e.g., LEA, chaperones, transporters) as well as regulatory genes, including transcription factors (TFs) belonging to various different classes, and genes associated with protein turnover. To further extend functional characterization, we identified the orthologs of differentially expressed unigenes in the model species Arabidopsis thaliana, which then allowed us to perform in silico functional inference, including gene network analysis for protein function, protein subcellular localization and gene co-expression, and in silico enrichment analysis for TFs and cis-elements. Results indicated the existence of extensive transcriptional regulatory events, including activation of ABA-responsive genes and ABF-dependent signaling. We were then able to establish that a core ABA-signaling pathway involving PP2C-SnRK2-ABF components was induced in stressed Q. suber roots, identifying a key mechanism in this species’ response to drought. PMID:26793200

  4. Root water potential integrates discrete soil physical properties to influence ABA signalling during partial rootzone drying.

    PubMed

    Dodd, Ian C; Egea, Gregorio; Watts, Chris W; Whalley, W Richard

    2010-08-01

    To investigate the influence of different growing substrates (two mineral, two organic) on root xylem ABA concentration ([ABA](root)) and the contribution of the drying root system to total sap flow during partial rootzone drying (PRD), sunflower (Helianthus annuus L.) shoots were grafted onto the root systems of two plants grown in separate pots. Sap flow through each hypocotyl was measured below the graft union when one pot ('wet') was watered and other ('dry') was not. Each substrate gave unique relationships between dry pot matric potential (Psi(soil)), volumetric water content ((v)) or penetrometer resistance (Q) and either the fraction of photoperiod sap flow from roots in drying soil or [ABA](root). However, decreased relative sap flow, and increased [ABA](root), from roots in drying soil varied with root water potential (Psi(root)) more similarly across a range of substrates. The gradient between Psi(soil) and Psi(root) was greater in substrates with high sand or peat proportions, which may have contributed to a more sensitive response of [ABA](root) to Psi(soil) in these substrates. Whole plant transpiration was most closely correlated with the mean Psi(soil) of both pots, and then with detached leaf xylem ABA concentration. Although Psi(root) best predicted decreased relative sap flow, and increased [ABA](root), from roots in drying soil across a range of substrates, the inaccessibility of this variable in field studies requires a better understanding of how measurable soil variables (Psi(soil), (v), Q) affect Psi(root).

  5. The cotton WRKY transcription factor GhWRKY17 functions in drought and salt stress in transgenic Nicotiana benthamiana through ABA signaling and the modulation of reactive oxygen species production.

    PubMed

    Yan, Huiru; Jia, Haihong; Chen, Xiaobo; Hao, Lili; An, Hailong; Guo, Xingqi

    2014-12-01

    Drought and high salinity are two major environmental factors that significantly limit the productivity of agricultural crops worldwide. WRKY transcription factors play essential roles in the adaptation of plants to abiotic stresses. However, WRKY genes involved in drought and salt tolerance in cotton (Gossypium hirsutum) are largely unknown. Here, a group IId WRKY gene, GhWRKY17, was isolated and characterized. GhWRKY17 was found to be induced after exposure to drought, salt, H2O2 and ABA. The constitutive expression of GhWRKY17 in Nicotiana benthamiana remarkably reduced plant tolerance to drought and salt stress, as determined through physiological analyses of the germination rate, root growth, survival rate, leaf water loss and Chl content. GhWRKY17 transgenic plants were observed to be more sensitive to ABA-mediated seed germination and root growth. However, overexpressing GhWRKY17 in N. benthamiana impaired ABA-induced stomatal closure. Furthermore, we found that GhWRKY17 modulated the increased sensitivity of plants to drought by reducing the level of ABA, and transcript levels of ABA-inducible genes, including AREB, DREB, NCED, ERD and LEA, were clearly repressed under drought and salt stress conditions. Consistent with the accumulation of reactive oxygen species (ROS), reduced proline contents and enzyme activities, elevated electrolyte leakage and malondialdehyde, and lower expression of ROS-scavenging genes, including APX, CAT and SOD, the GhWRKY17 transgenic plants exhibited reduced tolerance to oxidative stress compared with wild-type plants. These results therefore indicate that GhWRKY17 responds to drought and salt stress through ABA signaling and the regulation of cellular ROS production in plants.

  6. New fava bean guard cell signaling mutant impaired in ABA-induced stomatal closure.

    PubMed

    Iwai, Sumio; Shimomura, Naoki; Nakashima, Atsushi; Etoh, Takeomi

    2003-09-01

    We isolated a mutant from Vicia faba L. cv. House Ryousai. It wilts easily under strong light and high temperature conditions, suggesting that its stomatal movement may be disturbed. We determined responses of mutant guard cells to some environmental stimuli. Mutant guard cells demonstrated an impaired ability to respond to ABA in 0.1 mM CaCl(2) and stomata did not close in the presence of up to 1 mM ABA, whereas wild-type stomata closed when exposed to 10 micro M ABA. Elevating external Ca(2+) caused a similar degree of stomatal closure in the wild type and the mutant. A high concentration of CO(2) (700 micro l liter(-1)) induced stomatal closure in the wild type, but not in the mutant. On the basis of these results, we propose the working hypothesis that the mutation occurs in the region downstream of CO(2) and ABA sensing and in the region upstream of Ca(2+) elevation. The mutant is named fia (fava bean impaired in ABA-induced stomatal closure).

  7. Stomatal closure is induced by hydraulic signals and maintained by ABA in drought-stressed grapevine

    PubMed Central

    Tombesi, Sergio; Nardini, Andrea; Frioni, Tommaso; Soccolini, Marta; Zadra, Claudia; Farinelli, Daniela; Poni, Stefano; Palliotti, Alberto

    2015-01-01

    Water saving under drought stress is assured by stomatal closure driven by active (ABA-mediated) and/or passive (hydraulic-mediated) mechanisms. There is currently no comprehensive model nor any general consensus about the actual contribution and relative importance of each of the above factors in modulating stomatal closure in planta. In the present study, we assessed the contribution of passive (hydraulic) vs active (ABA mediated) mechanisms of stomatal closure in V. vinifera plants facing drought stress. Leaf gas exchange decreased progressively to zero during drought, and embolism-induced loss of hydraulic conductance in petioles peaked to ~50% in correspondence with strong daily limitation of stomatal conductance. Foliar ABA significantly increased only after complete stomatal closure had already occurred. Rewatering plants after complete stomatal closure and after foliar ABA reached maximum values did not induced stomatal re-opening, despite embolism recovery and water potential rise. Our data suggest that in grapevine stomatal conductance is primarily regulated by passive hydraulic mechanisms. Foliar ABA apparently limits leaf gas exchange over long-term, also preventing recovery of stomatal aperture upon rewatering, suggesting the occurrence of a mechanism of long-term down-regulation of transpiration to favor embolism repair and preserve water under conditions of fluctuating water availability and repeated drought events. PMID:26207993

  8. Reduced ABA Accumulation in the Root System is Caused by ABA Exudation in Upland Rice (Oryza sativa L. var. Gaoshan1) and this Enhanced Drought Adaptation.

    PubMed

    Shi, Lu; Guo, Miaomiao; Ye, Nenghui; Liu, Yinggao; Liu, Rui; Xia, Yiji; Cui, Suxia; Zhang, Jianhua

    2015-05-01

    Lowland rice (Nipponbare) and upland rice (Gaoshan 1) that are comparable under normal and moderate drought conditions showed dramatic differences in severe drought conditions, both naturally occurring long-term drought and simulated rapid water deficits. We focused on their root response and found that enhanced tolerance of upland rice to severe drought conditions was mainly due to the lower level of ABA in its roots than in those of the lowland rice. We first excluded the effect of ABA biosynthesis and catabolism on root-accumulated ABA levels in both types of rice by monitoring the expression of four OsNCED genes and two OsABA8ox genes. Next, we excluded the impact of the aerial parts on roots by suppressing leaf-biosynthesized ABA with fluridone and NDGA (nordihydroguaiaretic acid), and measuring the ABA level in detached roots. Instead, we proved that upland rice had the ability to export considerably more root-sourced ABA than lowland rice under severe drought, which improved ABA-dependent drought adaptation. The investigation of apoplastic pH in root cells and root anatomy showed that ABA leakage in the root system of upland rice was related to high apoplastic pH and the absence of Casparian bands in the sclerenchyma layer. Finally, taking some genes as examples, we predicted that different ABA levels in rice roots stimulated distinct ABA perception and signaling cascades, which influenced its response to water stress.

  9. Gladiolus hybridus ABSCISIC ACID INSENSITIVE 5 (GhABI5) is an important transcription factor in ABA signaling that can enhance Gladiolus corm dormancy and Arabidopsis seed dormancy

    PubMed Central

    Wu, Jian; Seng, Shanshan; Sui, Juanjuan; Vonapartis, Eliana; Luo, Xian; Gong, Benhe; Liu, Chen; Wu, Chenyu; Liu, Chao; Zhang, Fengqin; He, Junna; Yi, Mingfang

    2015-01-01

    The phytohormone abscisic acid (ABA) regulates plant development and is crucial for abiotic stress response. In this study, cold storage contributes to reducing endogenous ABA content, resulting in dormancy breaking of Gladiolus. The ABA inhibitor fluridone also promotes germination, suggesting that ABA is an important hormone that regulates corm dormancy. Here, we report the identification and functional characterization of the Gladiolus ABI5 homolog (GhABI5), which is a basic leucine zipper motif transcriptional factor (TF). GhABI5 is expressed in dormant vegetative organs (corm, cormel, and stolon) as well as in reproductive organs (stamen), and it is up-regulated by ABA or drought. Complementation analysis reveals that GhABI5 rescues the ABA insensitivity of abi5-3 during seed germination and induces the expression of downstream ABA response genes in Arabidopsis thaliana (EM1, EM6, and RD29B). Down-regulation of GhABI5 in dormant cormels via virus induced gene silence promotes sprouting and reduces the expression of downstream genes (GhLEA and GhRD29B). The results of this study reveal that GhABI5 regulates bud dormancy (vegetative organ) in Gladiolus in addition to its well-studied function in Arabidopsis seeds (reproductive organ). PMID:26579187

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

    PubMed Central

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

    2014-01-01

    Many fruit trees undergo cycles of heavy fruit load (ON-Crop) in one year, followed by low fruit load (OFF-Crop) the following year, a phenomenon known as alternate bearing (AB). The mechanism by which fruit load affects flowering induction during the following year (return bloom) is still unclear. Although not proven, it is commonly accepted that the fruit or an organ which senses fruit presence generates an inhibitory signal that moves into the bud and inhibits apical meristem transition. Indeed, fruit removal from ON-Crop trees (de-fruiting) induces return bloom. Identification of regulatory or metabolic processes modified in the bud in association with altered fruit load might shed light on the nature of the AB signalling process. The bud transcriptome of de-fruited citrus trees was compared with those of ON- and OFF-Crop trees. Fruit removal resulted in relatively rapid changes in global gene expression, including induction of photosynthetic genes and proteins. Altered regulatory mechanisms included abscisic acid (ABA) metabolism and auxin polar transport. Genes of ABA biosynthesis were induced; however, hormone analyses showed that the ABA level was reduced in OFF-Crop buds and in buds shortly following fruit removal. Additionally, genes associated with Ca2+-dependent auxin polar transport were remarkably induced in buds of OFF-Crop and de-fruited trees. Hormone analyses showed that auxin levels were reduced in these buds as compared with ON-Crop buds. In view of the auxin transport autoinhibition theory, the possibility that auxin distribution plays a role in determining bud fate is discussed. PMID:24706719

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

    PubMed

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

    2014-07-01

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

  12. An ABA-responsive DRE-binding protein gene from Setaria italica, SiARDP, the target gene of SiAREB, plays a critical role under drought stress

    PubMed Central

    Li, Cong; Yue, Jing; Wu, Xiaowei; Xu, Cong; Yu, Jingjuan

    2014-01-01

    The DREB (dehydration-responsive element binding)-type transcription factors regulate the expression of stress-inducible genes by binding the DRE/CRT cis-elements in promoter regions. The upstream transcription factors that regulate the transcription of DREB transcription factors have not been clearly defined, although the function of DREB transcription factors in abiotic stress is known. In this study, an abscisic acid (ABA)-responsive DREB-binding protein gene (SiARDP) was cloned from foxtail millet (Setaria italica). The transcript level of SiARDP increased not only after drought, high salt, and low temperature stresses, but also after an ABA treatment in foxtail millet seedlings. Two ABA-responsive elements (ABRE1: ACGTGTC; ABRE2: ACGTGGC) exist in the promoter of SiARDP. Further analyses showed that two ABA-responsive element binding (AREB)-type transcription factors, SiAREB1 and SiAREB2, could physically bind to the ABRE core element in vitro and in vivo. The constitutive expression of SiARDP in Arabidopsis thaliana enhanced drought and salt tolerance during seed germination and seedling development, and overexpression of SiARDP in foxtail millet improved drought tolerance. The expression levels of target genes of SiARDP were upregulated in transgenic Arabidopsis and foxtail millet. These results reveal that SiARDP, one of the target genes of SiAREB, is involved in ABA-dependent signal pathways and plays a critical role in the abiotic stress response in plants. PMID:25071221

  13. Overexpression of an ABA biosynthesis gene using a stress inducible promoter enhances drought resistance in petunia

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Plants respond to drought stress by closing their stomata and reducing transpirational water loss. The plant hormone abscisic acid (ABA) regulates growth and stomatal closure particularly when the plant is under environmental stresses. One of the key enzymes in the ABA biosynthesis of higher plants ...

  14. Nitric oxide and ABA in the control of plant function.

    PubMed

    Hancock, J T; Neill, S J; Wilson, I D

    2011-11-01

    Abscisic acid (ABA) and nitric oxide (NO) are both extremely important signalling molecules employed by plants to control many aspects of physiology. ABA has been extensively studied in the mechanisms which control stomatal movement as well as in seed dormancy and germination and plant development. The addition of either ABA or NO to plant cells is known to instigate the actions of many signal transduction components. Both may have an influence on the phosphorylation of proteins in cells mediated by effects on protein kinases and phosphatases, as well as recruiting a wide range of other signal transduction molecules to mediate the final effects. Both ABA and NO may also lead to the regulation of gene expression. However, it is becoming more apparent that NO may be acting downstream of ABA, with such action being mediated by reactive oxygen species such as hydrogen peroxide in some cases. However not all ABA responses require the action of NO. Here, examples of where ABA and NO have been put together into the same signal transduction pathways are discussed.

  15. Arabidopsis Tóxicos en Levadura 78 (AtATL78) mediates ABA-dependent ROS signaling in response to drought stress.

    PubMed

    Suh, Ji Yeon; Kim, Soo Jin; Oh, Tae Rin; Cho, Seok Keun; Yang, Seong Wook; Kim, Woo Taek

    2016-01-01

    Plants have developed a variety of complicated responses to cope with drought, one of the most challenging environmental stresses. As a quick response, plants rapidly inhibit stomatal opening under the control of abscisic acid (ABA) signaling pathway, in order to preserve water. Here, we report that Arabidopsis Tóxicos en Levadura (ATL), a RING-type E3 ubiquitin ligase, mediates the ABA-dependent stomatal closure. In contrast to wild-type plants, the stomatal closure was fully impaired in atatl78 mutant plants even in the presence of exogenous ABA and reactive oxygen species (ROS). Besides, under high concentrations of Ca(2+), a down-stream signaling molecule of ABA signaling pathway, atatl78 mutant plants successfully closed the pores. Furthermore, AtATL78 protein indirectly associated with catalases and the deficiency of AtATL78 led the reduction of catalase activity and H2O2, implying the function of AtATL78 in the modulation of ROS activity. Based on these results, we suggest that AtATL78 possibly plays a role in promoting ROS-mediated ABA signaling pathway during drought stress.

  16. ABA Inducible Rice Protein Phosphatase 2C Confers ABA Insensitivity and Abiotic Stress Tolerance in Arabidopsis

    PubMed Central

    Singh, Amarjeet; Jha, Saroj K.; Bagri, Jayram; Pandey, Girdhar K.

    2015-01-01

    Arabidopsis PP2C belonging to group A have been extensively worked out and known to negatively regulate ABA signaling. However, rice (Oryza sativa) orthologs of Arabidopsis group A PP2C are scarcely characterized functionally. We have identified a group A PP2C from rice (OsPP108), which is highly inducible under ABA, salt and drought stresses and localized predominantly in the nucleus. Genetic analysis revealed that Arabidopsis plants overexpressing OsPP108 are highly insensitive to ABA and tolerant to high salt and mannitol stresses during seed germination, root growth and overall seedling growth. At adult stage, OsPP108 overexpression leads to high tolerance to salt, mannitol and drought stresses with far better physiological parameters such as water loss, fresh weight, chlorophyll content and photosynthetic potential (Fv/Fm) in transgenic Arabidopsis plants. Expression profile of various stress marker genes in OsPP108 overexpressing plants revealed interplay of ABA dependent and independent pathway for abiotic stress tolerance. Overall, this study has identified a potential rice group A PP2C, which regulates ABA signaling negatively and abiotic stress signaling positively. Transgenic rice plants overexpressing this gene might provide an answer to the problem of low crop yield and productivity during adverse environmental conditions. PMID:25886365

  17. ABA inducible rice protein phosphatase 2C confers ABA insensitivity and abiotic stress tolerance in Arabidopsis.

    PubMed

    Singh, Amarjeet; Jha, Saroj K; Bagri, Jayram; Pandey, Girdhar K

    2015-01-01

    Arabidopsis PP2C belonging to group A have been extensively worked out and known to negatively regulate ABA signaling. However, rice (Oryza sativa) orthologs of Arabidopsis group A PP2C are scarcely characterized functionally. We have identified a group A PP2C from rice (OsPP108), which is highly inducible under ABA, salt and drought stresses and localized predominantly in the nucleus. Genetic analysis revealed that Arabidopsis plants overexpressing OsPP108 are highly insensitive to ABA and tolerant to high salt and mannitol stresses during seed germination, root growth and overall seedling growth. At adult stage, OsPP108 overexpression leads to high tolerance to salt, mannitol and drought stresses with far better physiological parameters such as water loss, fresh weight, chlorophyll content and photosynthetic potential (Fv/Fm) in transgenic Arabidopsis plants. Expression profile of various stress marker genes in OsPP108 overexpressing plants revealed interplay of ABA dependent and independent pathway for abiotic stress tolerance. Overall, this study has identified a potential rice group A PP2C, which regulates ABA signaling negatively and abiotic stress signaling positively. Transgenic rice plants overexpressing this gene might provide an answer to the problem of low crop yield and productivity during adverse environmental conditions.

  18. ITN1, a novel gene encoding an ankyrin-repeat protein that affects the ABA-mediated production of reactive oxygen species and is involved in salt-stress tolerance in Arabidopsis thaliana.

    PubMed

    Sakamoto, Hikaru; Matsuda, Osamu; Iba, Koh

    2008-11-01

    Salt stress and abscisic acid (ABA) induce accumulation of reactive oxygen species (ROS) in plant cells. ROS not only act as second messengers for the activation of salt-stress responses, but also have deleterious effects on plant growth due to their cytotoxicity. Therefore, the timing and degree of activation of ROS-producing or ROS-scavenging enzymes must be tightly regulated under salt-stress conditions. We identified a novel locus of Arabidopsis, designated itn1 (increased tolerance to NaCl1), whose disruption leads to increased salt-stress tolerance in vegetative tissues. ITN1 encodes a transmembrane protein with an ankyrin-repeat motif that has been implicated in diverse cellular processes such as signal transduction. Comparative microarray analysis between wild-type and the itn1 mutant revealed that induction of genes encoding the ROS-producing NADPH oxidases (RBOHC and RBOHD) under salt-stress conditions was suppressed in the mutant. This suppression was accompanied by a corresponding reduction in ROS accumulation. The ABA-induced expression of RBOHC and RBOHD was also suppressed in the mutant, as was the case for RD29A, an ABA-inducible marker gene. However, the ABA-induced expression of another marker gene, RD22, was not impaired in the mutant. These results suggest that the itn1 mutation partially impairs ABA signaling pathways, possibly leading to the reduction in ROS accumulation under salt-stress conditions. We discuss the possible mechanisms underlying the salt-tolerant phenotype of the itn1 mutant.

  19. Abscisic acid: biosynthesis, inactivation, homoeostasis and signalling.

    PubMed

    Dong, Ting; Park, Youngmin; Hwang, Inhwan

    2015-01-01

    The phytohormone abscisic acid (ABA) plays crucial roles in numerous physiological processes during plant growth and abiotic stress responses. The endogenous ABA level is controlled by complex regulatory mechanisms involving biosynthesis, catabolism, transport and signal transduction pathways. This complex regulatory network may target multiple levels, including transcription, translation and post-translational regulation of genes involved in ABA responses. Most of the genes involved in ABA biosynthesis, catabolism and transport have been characterized. The local ABA concentration is critical for initiating ABA-mediated signalling during plant development and in response to environmental changes. In this chapter we discuss the mechanisms that regulate ABA biosynthesis, catabolism, transport and homoeostasis. We also present the findings of recent research on ABA perception by cellular receptors, and ABA signalling in response to cellular and environmental conditions.

  20. Overexpression of the phosphatidylinositol synthase gene (ZmPIS) conferring drought stress tolerance by altering membrane lipid composition and increasing ABA synthesis in maize.

    PubMed

    Liu, Xiuxia; Zhai, Shumei; Zhao, Yajie; Sun, Baocheng; Liu, Cheng; Yang, Aifang; Zhang, Juren

    2013-05-01

    Phosphatidylinositol (PtdIns) synthase is a key enzyme in the phospholipid pathway and catalyses the formation of PtdIns. PtdIns is not only a structural component of cell membranes, but also the precursor of the phospholipid signal molecules that regulate plant response to environment stresses. Here, we obtained transgenic maize constitutively overexpressing or underexpressing PIS from maize (ZmPIS) under the control of a maize ubiquitin promoter. Transgenic plants were confirmed by PCR, Southern blotting analysis and real-time RT-PCR assay. The electrospray ionization tandem mass spectrometry (ESI-MS/MS)-based lipid profiling analysis showed that, under drought stress conditions, the overexpression of ZmPIS in maize resulted in significantly elevated levels of most phospholipids and galactolipids in leaves compared with those in wild type (WT). At the same time, the expression of some genes involved in the phospholipid metabolism pathway and the abscisic acid (ABA) biosynthesis pathway including ZmPLC, ZmPLD, ZmDGK1, ZmDGK3, ZmPIP5K9, ZmABA1, ZmNCED, ZmAAO1, ZmAAO2 and ZmSCA1 was markedly up-regulated in the overexpression lines after drought stress. Consistent with these results, the drought stress tolerance of the ZmPIS sense transgenic plants was enhanced significantly at the pre-flowering stages compared with WT maize plants. These results imply that ZmPIS regulates the plant response to drought stress through altering membrane lipid composition and increasing ABA synthesis in maize.

  1. The ABA receptors -- we report you decide.

    PubMed

    McCourt, Peter; Creelman, Robert

    2008-10-01

    The plant hormone abscisic acid (ABA) has been implicated in a variety of physiological responses ranging from seed dormancy to stomatal conductance. Recently, three groups have reported the molecular identification of three disparate ABA receptors. Unlike the identification of other hormone receptors, in these three cases high affinity binding to ABA rather than the isolation of ABA insensitive mutants led to these receptor genes. Interestingly, two of the receptors encode genes involved in floral timing and chlorophyll biosynthesis, which are not considered traditional ABA responses. And the third receptor has been clouded in issues of its molecular identity. To clearly determine the roles of these genes in ABA perception it will require placing of these ABA-binding proteins into the rich ABA physiological context that has built up over the years.

  2. Functional roles of the pepper RING finger protein gene, CaRING1, in abscisic acid signaling and dehydration tolerance.

    PubMed

    Lim, Chae Woo; Hwang, Byung Kook; Lee, Sung Chul

    2015-09-01

    Plants are constantly exposed to a variety of biotic and abiotic stresses, which include pathogens and conditions of high salinity, low temperature, and drought. Abscisic acid (ABA) is a major plant hormone involved in signal transduction pathways that mediate the defense response of plants to abiotic stress. Previously, we isolated Ring finger protein gene (CaRING1) from pepper (Capsicum annuum), which is associated with resistance to bacterial pathogens, accompanied by hypersensitive cell death. Here, we report a new function of the CaRING1 gene product in the ABA-mediated defense responses of plants to dehydration stress. The expression of the CaRING1 gene was induced in pepper leaves treated with ABA or exposed to dehydration or NaCl. Virus-induced gene silencing of CaRING1 in pepper plants exhibited low degree of ABA-induced stomatal closure and high levels of transpirational water loss in dehydrated leaves. These led to be more vulnerable to dehydration stress in CaRING1-silenced pepper than in the control pepper, accompanied by reduction of ABA-regulated gene expression and low accumulation of ABA and H2O2. In contrast, CaRING1-overexpressing transgenic plants showed enhanced sensitivity to ABA during the seedling growth and establishment. These plants were also more tolerant to dehydration stress than the wild-type plants because of high ABA accumulation, enhanced stomatal closure and increased expression of stress-responsive genes. Together, these results suggest that the CaRING1 acts as positive factor for dehydration tolerance in Arabidopsis by modulating ABA biosynthesis and ABA-mediated stomatal closing and gene expression.

  3. ABA crosstalk with ethylene and nitric oxide in seed dormancy and germination

    PubMed Central

    Arc, Erwann; Sechet, Julien; Corbineau, Françoise; Rajjou, Loïc; Marion-Poll, Annie

    2013-01-01

    Dormancy is an adaptive trait that enables seed germination to coincide with favorable environmental conditions. It has been clearly demonstrated that dormancy is induced by abscisic acid (ABA) during seed development on the mother plant. After seed dispersal, germination is preceded by a decline in ABA in imbibed seeds, which results from ABA catabolism through 8′-hydroxylation. The hormonal balance between ABA and gibberellins (GAs) has been shown to act as an integrator of environmental cues to maintain dormancy or activate germination. The interplay of ABA with other endogenous signals is however less documented. In numerous species, ethylene counteracts ABA signaling pathways and induces germination. In Brassicaceae seeds, ethylene prevents the inhibitory effects of ABA on endosperm cap weakening, thereby facilitating endosperm rupture and radicle emergence. Moreover, enhanced seed dormancy in Arabidopsis ethylene-insensitive mutants results from greater ABA sensitivity. Conversely, ABA limits ethylene action by down-regulating its biosynthesis. Nitric oxide (NO) has been proposed as a common actor in the ABA and ethylene crosstalk in seed. Indeed, convergent evidence indicates that NO is produced rapidly after seed imbibition and promotes germination by inducing the expression of the ABA 8′-hydroxylase gene, CYP707A2, and stimulating ethylene production. The role of NO and other nitrogen-containing compounds, such as nitrate, in seed dormancy breakage and germination stimulation has been reported in several species. This review will describe our current knowledge of ABA crosstalk with ethylene and NO, both volatile compounds that have been shown to counteract ABA action in seeds and to improve dormancy release and germination. PMID:23531630

  4. ABA crosstalk with ethylene and nitric oxide in seed dormancy and germination.

    PubMed

    Arc, Erwann; Sechet, Julien; Corbineau, Françoise; Rajjou, Loïc; Marion-Poll, Annie

    2013-01-01

    Dormancy is an adaptive trait that enables seed germination to coincide with favorable environmental conditions. It has been clearly demonstrated that dormancy is induced by abscisic acid (ABA) during seed development on the mother plant. After seed dispersal, germination is preceded by a decline in ABA in imbibed seeds, which results from ABA catabolism through 8'-hydroxylation. The hormonal balance between ABA and gibberellins (GAs) has been shown to act as an integrator of environmental cues to maintain dormancy or activate germination. The interplay of ABA with other endogenous signals is however less documented. In numerous species, ethylene counteracts ABA signaling pathways and induces germination. In Brassicaceae seeds, ethylene prevents the inhibitory effects of ABA on endosperm cap weakening, thereby facilitating endosperm rupture and radicle emergence. Moreover, enhanced seed dormancy in Arabidopsis ethylene-insensitive mutants results from greater ABA sensitivity. Conversely, ABA limits ethylene action by down-regulating its biosynthesis. Nitric oxide (NO) has been proposed as a common actor in the ABA and ethylene crosstalk in seed. Indeed, convergent evidence indicates that NO is produced rapidly after seed imbibition and promotes germination by inducing the expression of the ABA 8'-hydroxylase gene, CYP707A2, and stimulating ethylene production. The role of NO and other nitrogen-containing compounds, such as nitrate, in seed dormancy breakage and germination stimulation has been reported in several species. This review will describe our current knowledge of ABA crosstalk with ethylene and NO, both volatile compounds that have been shown to counteract ABA action in seeds and to improve dormancy release and germination.

  5. Salicylic acid mediates antioxidant defense system and ABA pathway related gene expression in Oryza sativa against quinclorac toxicity.

    PubMed

    Wang, Jian; Lv, Mengting; Islam, Faisal; Gill, Rafaqat A; Yang, Chong; Ali, Basharat; Yan, Guijun; Zhou, Weijun

    2016-11-01

    The auxin herbicide quinclorac is widely used for controlling weeds in transplanted and direct-seeded rice fields. However, its phytotoxic responses on rice are still unknown. Therefore, in the present investigation we studied the effects of different concentrations (0, 0.1 and 0.5g/L) of quinclorac herbicide on the physiological and biochemical changes of two rice cultivars (XS 134 and ZJ 88) and further analyzed the ameliorating role of salicylic acid (SA) on quinclorac toxicity in rice plants. The results revealed that exogenous application of SA significantly increased plant biomass and total chlorophyll contents in herbicide stressed plants. The lipid peroxidation and ROS (H2O2, O2(-.), (-)OH) production were significantly increased in roots and leaves of both rice cultivars under quinclorac stress, demonstrating an oxidative burst in rice plants. Whereas, application of SA significantly lowered ROS contents under quinclorac stress. Further, exogenous SA treatment significantly modulated antioxidant enzymes and enhanced GSH concentration in stress plants. Anatomical observations of leaf and root revealed that herbicide affected internal structures, while SA played a vital role in protection from toxic effects. Expression analysis of stress hormone ABA genes (OsABA8oxs, OsNCEDs) revealed that quinclorac application enhanced stress condition in cultivar ZJ 88, while SA treatment downregulated ABA genes more in cultivar XS 134, which correlated with the enhanced tolerance to quinclorac induced oxidative stress in this cultivar. The present study delineated that SA played a critical role under quinclorac stress in both rice cultivars by regulating antioxidant defense system, reducing ROS formation and preventing the degradation of internal cell organelles.

  6. RING Type E3 Ligase CaAIR1 in Pepper Acts in the Regulation of ABA Signaling and Drought Stress Response.

    PubMed

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

    2015-09-01

    Several E3 ubiquitin ligases have been associated with the response to abiotic and biotic stresses in higher plants. Here, we report that the hot pepper (Capsicum annuum) ABA-Insensitive RING protein 1 gene (CaAIR1) is essential for a hypersensitive response to drought stress. CaAIR1 contains a C3HC4-type RING finger motif, which plays a role for attachment of ubiquitins to the target protein, and a putative transmembrane domain. The expression levels of CaAIR1 are up-regulated in pepper leaves by ABA treatments, drought and NaCl, suggesting its role in the response to abiotic stress. Our analysis showed that CaAIR1 displays self-ubiquitination and is localized in the nucleus. We generated CaAIR1-silenced peppers via virus-induced gene silencing (VIGS) and CaAIR1-overexpressing (OX) transgenic Arabidopsis plants to evaluate their responses to ABA and drought. VIGS of CaAIR1 in pepper plants conferred an enhanced tolerance to drought stress, which was accompanied by low levels of transpirational water loss in the drought-treated leaves. CaAIR1-OX plants displayed an impaired sensitivity to ABA during seed germination, seedling and adult stages. Moreover, these plants showed enhanced sensitivity to drought stress because of reduced stomatal closure and decreased expression of stress-responsive genes. Thus, our data indicate that CaAIR1 is a negative regulator of the ABA-mediated drought stress tolerance mechanism.

  7. ABA Receptors: Past, Present and Future

    SciTech Connect

    Guo, Jianjun; Yang, Xiaohan; Weston, David; Chen, Jay

    2011-01-01

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

  8. The Citrus ABA signalosome: identification and transcriptional regulation during sweet orange fruit ripening and leaf dehydration

    PubMed Central

    Rodrigo, María J.

    2012-01-01

    The abscisic acid (ABA) signalling core in plants include the cytosolic ABA receptors (PYR/PYL/RCARs), the clade-A type 2C protein phosphatases (PP2CAs), and the subclass III SNF1-related protein kinases 2 (SnRK2s). The aim of this work was to identify these ABA perception system components in sweet orange and to determine the influence of endogenous ABA on their transcriptional regulation during fruit development and ripening, taking advantage of the comparative analysis between a wild-type and a fruit-specific ABA-deficient mutant. Transcriptional changes in the ABA signalosome during leaf dehydration were also studied. Six PYR/PYL/RCAR, five PP2CA, and two subclass III SnRK2 genes, homologous to those of Arabidopsis, were identified in the Citrus genome. The high degree of homology and conserved motifs for protein folding and for functional activity suggested that these Citrus proteins are bona fide core elements of ABA perception in orange. Opposite expression patterns of CsPYL4 and CsPYL5 and ABA accumulation were found during ripening, although there were few differences between varieties. In contrast, changes in expression of CsPP2CA genes during ripening paralleled those of ABA content and agreeed with the relevant differences between wild-type and mutant fruit transcript accumulation. CsSnRK2 gene expression continuously decreased with ripening and no remarkable differences were found between cultivars. Overall, dehydration had a minor effect on CsPYR/PYL/RCAR and CsSnRK2 expression in vegetative tissue, whereas CsABI1, CsAHG1, and CsAHG3 were highly induced by water stress. The global results suggest that responsiveness to ABA changes during citrus fruit ripening, and leaf dehydration was higher in the CsPP2CA gene negative regulators than in the other ABA signalosome components. PMID:22888124

  9. Identification and functional expression of the pepper RING type E3 ligase, CaDTR1, involved in drought stress tolerance via ABA-mediated signalling

    PubMed Central

    Joo, Hyunhee; Lim, Chae Woo; Lee, Sung Chul

    2016-01-01

    Drought negatively affects plant growth and development, thereby leading to loss of crop productivity. Several plant E3 ubiquitin ligases act as positive or negative regulators of abscisic acid (ABA) and thus play important roles in the drought stress response. Here, we show that the C3HC4-type RING finger E3 ligase, CaDTR1, regulates the drought stress response via ABA-mediated signalling. CaDTR1 contains an amino-terminal RING finger motif and two carboxyl-terminal hydrophobic regions; the RING finger motif functions during attachment of ubiquitins to the target proteins, and the carboxyl-terminal hydrophobic regions function during subcellular localisation. The expression of CaDTR1 was induced by ABA, drought, and NaCl treatments. CaDTR1 localised in the nucleus and displayed in vitro E3 ubiquitin ligase activity. CaDTR1-silenced pepper plants exhibited a drought-sensitive phenotype characterised by high levels of transpirational water loss. On the other hand, CaDTR1-overexpressing (OX) Arabidopsis plants exhibited an ABA-hypersensitive phenotype during the germinative and post-germinative growth stages. Moreover, in contrast to CaDTR1-silenced pepper plants, CaDTR1-OX plants exhibited a drought-tolerant phenotype characterised by low levels of transpirational water loss via increased stomatal closure and high leaf temperatures. Our data indicate that CaDTR1 functions as a positive regulator of the drought stress response via ABA-mediated signalling. PMID:27439598

  10. The NAC-type transcription factor OsNAC2 regulates ABA-dependent genes and abiotic stress tolerance in rice

    PubMed Central

    Shen, Jiabin; Lv, Bo; Luo, Liqiong; He, Jianmei; Mao, Chanjuan; Xi, Dandan; Ming, Feng

    2017-01-01

    Plants can perceive environmental changes and respond to external stressors. Here, we show that OsNAC2, a member of the NAC transcription factor family, was strongly induced by ABA and osmotic stressors such as drought and high salt. With reduced yields under drought conditions at the flowering stage, OsNAC2 overexpression lines had lower resistance to high salt and drought conditions. RNAi plants showed enhanced tolerance to high salinity and drought stress at both the vegetative and flowering stages. Furthermore, RNAi plants had improved yields after drought stress. A microarray assay indicated that many ABA-dependent stress-related genes were down-regulated in OsNAC2 overexpression lines. We further confirmed that OsNAC2 directly binds the promoters of LATE EMBRYOGENESIS ABUNDANT 3 (OsLEA3) and Stress-Activated Protein Kinases 1 (OsSAPK1), two marker genes in the abiotic stress and ABA response pathways, respectively. Our results suggest that in rice OsNAC2 regulates both abiotic stress responses and ABA-mediated responses, and acts at the junction between the ABA and abiotic stress pathways. PMID:28074873

  11. Involvement of CmWRKY10 in Drought Tolerance of Chrysanthemum through the ABA-Signaling Pathway.

    PubMed

    Jaffar, Muhammad Abuzar; Song, Aiping; Faheem, Muhammad; Chen, Sumei; Jiang, Jiafu; Liu, Chen; Fan, Qingqing; Chen, Fadi

    2016-05-11

    Drought is one of the important abiotic factors that adversely affects plant growth and production. The WRKY transcription factor plays a pivotal role in plant growth and development, as well as in the elevation of many abiotic stresses. Among three major groups of the WRKY family, the group IIe WRKY has been the least studied in floral crops. Here, we report functional aspects of group IIe WRKY member, i.e., CmWRKY10 in chrysanthemum involved in drought tolerance. The transactivation assay showed that CmWRKY10 had transcriptional activity in yeast cells and subcellular localization demonstrated that it was localized in nucleus. Our previous study showed that CmWRKY10 could be induced by drought in chrysanthemum. Moreover, the overexpression of CmWRKY10 in transgenic chrysanthemum plants improved tolerance to drought stress compared to wild-type (WT). High expression of DREB1A, DREB2A, CuZnSOD, NCED3A, and NCED3B transcripts in overexpressed plants provided strong evidence that drought tolerance mechanism was associated with abscisic acid (ABA) pathway. In addition, lower accumulation of reactive oxygen species (ROS) and higher enzymatic activity of peroxidase, superoxide dismutase and catalase in CmWRKY10 overexpressed lines than that of WT demonstrates its role in drought tolerance. Together, these findings reveal that CmWRKY10 works as a positive regulator in drought stress by regulating stress-related genes.

  12. Stomatal malfunctioning under low VPD conditions: induced by alterations in stomatal morphology and leaf anatomy or in the ABA signaling?

    PubMed

    Aliniaeifard, Sasan; Malcolm Matamoros, Priscila; van Meeteren, Uulke

    2014-12-01

    Exposing plants to low VPD reduces leaf capacity to maintain adequate water status thereafter. To find the impact of VPD on functioning of stomata, stomatal morphology and leaf anatomy, fava bean plants were grown at low (L, 0.23 kPa) or moderate (M, 1.17 kPa) VPDs and some plants that developed their leaves at moderate VPD were then transferred for 4 days to low VPD (M→L). Part of the M→L-plants were sprayed with ABA (abscisic acid) during exposure to L. L-plants showed bigger stomata, larger pore area, thinner leaves and less spongy cells compared with M-plants. Stomatal morphology (except aperture) and leaf anatomy of the M→L-plants were almost similar to the M-plants, while their transpiration rate and stomatal conductance were identical to that of L-plants. The stomatal response to ABA was lost in L-plants, but also after 1-day exposure of M-plants to low VPD. The level of foliar ABA sharply decreased within 1-day exposure to L, while the level of ABA-GE (ABA-glucose ester) was not affected. Spraying ABA during the exposure to L prevented loss of stomatal closing response thereafter. The effect of low VPD was largely depending on exposure time: the stomatal responsiveness to ABA was lost after 1-day exposure to low VPD, while the responsiveness to desiccation was gradually lost during 4-day exposure to low VPD. Leaf anatomical and stomatal morphological alterations due to low VPD were not the main cause of loss of stomatal closure response to closing stimuli.

  13. CsWRKY46, a WRKY transcription factor from cucumber, confers cold resistance in transgenic-plant by regulating a set of cold-stress responsive genes in an ABA-dependent manner.

    PubMed

    Zhang, Ying; Yu, Hongjun; Yang, Xueyong; Li, Qiang; Ling, Jian; Wang, Hong; Gu, Xingfang; Huang, Sanwen; Jiang, Weijie

    2016-11-01

    Plant WRKY transcription factors are trans-regulatory proteins that are involved in plant immune responses, development and senescence; however, their roles in abiotic stress are still not well understood, especially in the horticultural crop cucumber. In this study, a novel cucumber WRKY gene, CsWRKY46 was cloned and identified, which was up-regulated in response to cold stress and exogenous abscisic acid (ABA) treatment. CsWRKY46 is belonging to group II of the WRKY family, CsWRKY46 was found exclusively in the nucleus, as indicated by a transient expression assay. Yeast one-hybrid assay shown that CsWRKY46 interact with the W-box in the promoter of ABI5. Transgenic Arabidopsis lines over-expressing CsWRKY46, WRK46-OE1 and WRK46-OE5 had higher seedling survival rates upon freezing treatment compared with that of the wild-type. The above over-expression lines also showed much a higher proline accumulation, less electrolyte leakage and lower malondialdehyde (MDA) levels. Furthermore, the CsWRKY46 overexpression lines were hypersensitive to ABA during seed germination, but the seedlings were not. Quantitative RT-PCR analyses revealed that the expression levels of the ABA-responsive transcription factor ABI5 were higher in the WRKY46-OE lines than in wild-type and that the overexpression of CsWRKY46 increased the expression of stress-inducible genes, including RD29A and COR47. Taken together, our results demonstrated that CsWRKY46 from cucumber conferred cold tolerance to transgenic plants and positively regulated the cold signaling pathway in an ABA-dependent manner.

  14. ABA accumulation in water-stressed Citrus roots does not rely on carotenoid content in this organ.

    PubMed

    Manzi, Matías; Lado, Joanna; Rodrigo, María Jesús; Arbona, Vicent; Gómez-Cadenas, Aurelio

    2016-11-01

    Sustained abscisic acid (ABA) accumulation in dehydrated citrus roots depends on the transport from aerial organs. Under this condition, the role of the β,β-carotenoids (ABA precursors) to the de novo synthesis of ABA in roots needs to be clarified since their low availability in this organ restricts its accumulation. To accomplish that, detached citrus roots were exposed to light (to increase their carotenoid content) and subsequently dehydrated (to trigger ABA accumulation). Stress imposition sharply decreased the pool of β,β-carotenoids but, unexpectedly, no concomitant rise in ABA content was observed. Contrastingly, roots of intact plants (with low levels of carotenoids) showed a similar decrease of ABA precursor together with a significant ABA accumulation. Furthermore, upon dehydration both types of roots showed similar upregulation of the key genes involved in biosynthesis of carotenoids and ABA (CsPSY3a; CsβCHX1; CsβCHX2; CsNCED1; CsNCED2), demonstrating a conserved transcriptional response triggered by water stress. Thus, the sharp decrease in root carotenoid levels in response to dehydration should be related to other stress-related signals instead of contributing to ABA biosynthesis. In summary, ABA accumulation in dehydrated-citrus roots largely relies on the presence of the aerial organs and it is independent of the amount of available root β,β-carotenoids.

  15. Cross-species approaches to seed dormancy and germination: conservation and biodiversity of ABA-regulated mechanisms and the Brassicaceae DOG1 genes.

    PubMed

    Graeber, Kai; Linkies, Ada; Müller, Kerstin; Wunchova, Andrea; Rott, Anita; Leubner-Metzger, Gerhard

    2010-05-01

    Seed dormancy is genetically determined with substantial environmental influence mediated, at least in part, by the plant hormone abscisic acid (ABA). The ABA-related transcription factor ABI3/VP1 (ABA INSENSITIVE3/VIVIPAROUS1) is widespread among green plants. Alternative splicing of its transcripts appears to be involved in regulating seed dormancy, but the role of ABI3/VP1 goes beyond seeds and dormancy. In contrast, DOG1 (DELAY OF GERMINATION 1), a major quantitative trait gene more specifically involved in seed dormancy, was so far only known from Arabidopsis thaliana (AtDOG1) and whether it also has roles during the germination of non-dormant seeds was not known. Seed germination of Lepidium sativum ('garden cress') is controlled by ABA and its antagonists gibberellins and ethylene and involves the production of apoplastic hydroxyl radicals. We found orthologs of AtDOG1 in the Brassicaceae relatives L. sativum (LesaDOG1) and Brassica rapa (BrDOG1) and compared their gene structure and the sequences of their transcripts expressed in seeds. Tissue-specific analysis of LesaDOG1 transcript levels in L. sativum seeds showed that they are degraded upon imbibition in the radicle and the micropylar endosperm. ABA inhibits germination in that it delays radicle protrusion and endosperm weakening and it increased LesaDOG1 transcript levels during early germination due to enhanced transcription and/or inhibited degradation. A reduced decrease in LesaDOG1 transcript levels upon ABA treatment is evident in the late germination phase in both tissues. This temporal and ABA-related transcript expression pattern suggests a role for LesaDOG1 in the control of germination timing of non-dormant L. sativum seeds. The possible involvement of the ABA-related transcription factors ABI3 and ABI5 in the regulation of DOG1 transcript expression is discussed. Other species of the monophyletic genus Lepidium showed coat or embryo dormancy and are therefore highly suited for comparative

  16. Production of ABA responses requires both the nuclear and cytoplasmic functional involvement of PYR1.

    PubMed

    Park, EunJoo; Kim, Tae-Houn

    2017-02-26

    Abscisic acid (ABA) enhances stress tolerant responses in plants against unfavorable environmental conditions. In Arabidopsis, ABA promotes interactions between PYR/PYL/RCARs and PP2C, thereby allowing SnRK2s to phosphorylate downstream components required for the regulation of gene expression or for gating ion channels. Because PYR1 is known to localize to nucleus and cytoplasm it is a question whether nuclear or cytoplasmic PYR1 confer different functions to the ABA signaling pathway, as has been previously shown for regulatory proteins. In order to answer this question, transgenic lines expressing nuclear PYR1 were generated in an ABA insensitive mutant background. Enforced nuclear expression of PYR1 was examined by confocal microscopy and western blot analysis. Physiological analyses of the transgenic lines demonstrated that nuclear PYR1 is sufficient to generate ABA responses, such as, the inhibition of seed germination, root growth inhibition, the induction of gene expression, and stomatal closing movement. However, for the full recovery of ABA responses in the mutant background cytoplasmic PYR1 was required. The study suggests both nuclear and cytoplasmic PYR1 participate in the control of ABA signal transduction.

  17. Liming can decrease legume crop yield and leaf gas exchange by enhancing root to shoot ABA signalling.

    PubMed

    Rothwell, Shane A; Elphinstone, E David; Dodd, Ian C

    2015-04-01

    To meet future requirements for food production, sustainable intensive agricultural systems need to optimize nutrient availability to maximize yield, traditionally achieved by maintaining soil pH within an optimal range (6-6.5) by applying lime (calcium carbonate). However, a field trial that applied recommended liming rates to a sandy loam soil (increasing soil pH from 5.5 to 6.2) decreased pod yield of field bean (Vicia faba L. cv. Fuego) by ~30%. Subsequent pot trials, with liming that raised soil pH to 6.3-6.7, reduced stomatal conductance (g(s)) by 63, 26, and 59% in V. faba, bean (Phaseolus vulgaris), and pea (Pisum sativum), respectively. Furthermore, liming reduced shoot dry biomass by 16-24% in these species. Ionomic analysis of root xylem sap and leaf tissue revealed a decrease in phosphorus concentration that was correlated with decreased g(s): both reductions were partially reversed by adding superphosphate fertilizer. Further analysis of pea suggests that leaf gas exchange was reduced by a systemic increase (roots, xylem sap, and leaves) in the phytohormone abscisic acid (ABA) in response to lime-induced suboptimal plant phosphorus concentrations. Supplying synthetic ABA via the transpiration stream to detached pea leaves, at the same xylem sap concentrations induced by liming, decreased transpiration. Furthermore, the g(s) of the ABA-deficient mutant pea wilty was unresponsive to liming, apparently confirming that ABA mediates some responses to low phosphorus availability caused by liming. This research provides a detailed mechanistic understanding of the physiological processes by which lime application can limit crop yields, and questions the suitability of current liming recommendations.

  18. Liming can decrease legume crop yield and leaf gas exchange by enhancing root to shoot ABA signalling

    PubMed Central

    Rothwell, Shane A.; Elphinstone, E. David; Dodd, Ian C.

    2015-01-01

    To meet future requirements for food production, sustainable intensive agricultural systems need to optimize nutrient availability to maximize yield, traditionally achieved by maintaining soil pH within an optimal range (6–6.5) by applying lime (calcium carbonate). However, a field trial that applied recommended liming rates to a sandy loam soil (increasing soil pH from 5.5 to 6.2) decreased pod yield of field bean (Vicia faba L. cv. Fuego) by ~30%. Subsequent pot trials, with liming that raised soil pH to 6.3–6.7, reduced stomatal conductance (g s) by 63, 26, and 59% in V. faba, bean (Phaseolus vulgaris), and pea (Pisum sativum), respectively. Furthermore, liming reduced shoot dry biomass by 16–24% in these species. Ionomic analysis of root xylem sap and leaf tissue revealed a decrease in phosphorus concentration that was correlated with decreased g s: both reductions were partially reversed by adding superphosphate fertilizer. Further analysis of pea suggests that leaf gas exchange was reduced by a systemic increase (roots, xylem sap, and leaves) in the phytohormone abscisic acid (ABA) in response to lime-induced suboptimal plant phosphorus concentrations. Supplying synthetic ABA via the transpiration stream to detached pea leaves, at the same xylem sap concentrations induced by liming, decreased transpiration. Furthermore, the g s of the ABA-deficient mutant pea wilty was unresponsive to liming, apparently confirming that ABA mediates some responses to low phosphorus availability caused by liming. This research provides a detailed mechanistic understanding of the physiological processes by which lime application can limit crop yields, and questions the suitability of current liming recommendations. PMID:25740925

  19. A G-protein β subunit, AGB1, negatively regulates the ABA response and drought tolerance by down-regulating AtMPK6-related pathway in Arabidopsis.

    PubMed

    Xu, Dong-bei; Chen, Ming; Ma, Ya-nan; Xu, Zhao-shi; Li, Lian-cheng; Chen, Yao-feng; Ma, You-zhi

    2015-01-01

    Heterotrimeric G-proteins are versatile regulators involved in diverse cellular processes in eukaryotes. In plants, the function of G-proteins is primarily associated with ABA signaling. However, the downstream effectors and the molecular mechanisms in the ABA pathway remain largely unknown. In this study, an AGB1 mutant (agb1-2) was found to show enhanced drought tolerance, indicating that AGB1 might negatively regulate drought tolerance in Arabidopsis. Data showed that AGB1 interacted with protein kinase AtMPK6 that was previously shown to phosphorylate AtVIP1, a transcription factor responding to ABA signaling. Our study found that transcript levels of three ABA responsive genes, AtMPK6, AtVIP1 and AtMYB44 (downstream gene of AtVIP1), were significantly up-regulated in agb1-2 lines after ABA or drought treatments. Other ABA-responsive and drought-inducible genes, such as RD29A (downstream gene of AtMYB44), were also up-regulated in agb1-2 lines. Furthermore, overexpression of AtVIP1 resulted in hypersensitivity to ABA at seed germination and seedling stages, and significantly enhanced drought tolerance in transgenic plants. These results suggest that AGB1 was involved in the ABA signaling pathway and drought tolerance in Arabidopsis through down-regulating the AtMPK6, AtVIP1 and AtMYB44 cascade.

  20. Accumulation of the hormone abscisic acid (ABA) at the infection site of the fungus Cercospora beticola supports the role of ABA as a repressor of plant defence in sugar beet.

    PubMed

    Schmidt, Klaus; Pflugmacher, Maike; Klages, Simone; Mäser, Anja; Mock, Andrea; Stahl, Dietmar J

    2008-09-01

    Inducible plant defence responses in sugar beet (Beta vulgaris L.) leaves are repressed during the early phase of infection by the fungus Cercospora beticola. In this report, we show that the concentration of the plant hormone abscisic acid (ABA) increases in sugar beet leaves during C. beticola infection. After an initial burst of ABA induced by inoculation of the fungus, elevated ABA concentrations were detected during the fungal penetration and colonization phases 3-9 days after inoculation. Fifteen days after inoculation, with visible onset of the necrotic phase of infection, the strongly elevated ABA concentrations in infected leaves were at levels similar to drought-stressed plants. A synthetic promoter composed of four copies of the ABA-responsive element (ABRE) A2 and the coupling element CE3 of the ABA-inducible barley gene HVA1 was strongly induced by ABA and C. beticola infection in transgenic sugar beet leaves. Analysis of the spatial pattern of promoter activity revealed that the ABA-inducible promoter was locally activated at the fungal infection sites. Furthermore, expression of the basic leucine zipper transcription factor AREB1 was induced by drought stress and fungal infection in the sugar beet. Application of ABA reduced the promoter activity of the phenylalanine ammonia lyase (BvPAL) gene, and this effect was observed with the -34 to +248 BvPAL promoter region. This region is equivalent to the core promoter, which is necessary for the suppression of BvPAL expression by C. beticola, as recently shown. These data indicate that ABA accumulation and activation of the ABA-dependent signalling cascade are the primary cause of suppression of BvPAL expression during infection of sugar beet leaves.

  1. Physiological responses of potato (Solanum tuberosum L.) to partial root-zone drying: ABA signalling, leaf gas exchange, and water use efficiency.

    PubMed

    Liu, Fulai; Shahnazari, Ali; Andersen, Mathias N; Jacobsen, Sven-Erik; Jensen, Christian R

    2006-01-01

    The physiological responses of potato (Solanum tuberosum L. cv. Folva) to partial root-zone drying (PRD) were investigated in potted plants in a greenhouse (GH) and in plants grown in the field under an automatic rain-out-shelter. In the GH, irrigation was applied daily to the whole root system (FI), or to one-half of the root system while the other half was dried, for 9 d. In the field, the plants were drip irrigated either to the whole root system near field capacity (FI) or using 70% water of FI to one side of the roots, and shifted to the other side every 5-10 d (PRD). PRD plants had a similar midday leaf water potential to that of FI, whereas in the GH their root water potential (Psi(r)) was significantly lowered after 5 d. Stomatal conductance (g(s)) was more sensitive to PRD than photosynthesis (A) particularly in the field, leading to greater intrinsic water use efficiency (WUE) (i.e. A/g(s)) in PRD than in FI plants on several days. In PRD, the xylem sap abscisic acid concentration ([ABA](xylem)) increased exponentially with decreasing Psi(r); and the relative [ABA](xylem) (PRD/FI) increased exponentially as the fraction of transpirable soil water (FTSW) in the drying side decreased. In the field, the leaf area index was slightly less in PRD than in FI treatment, while tuber biomass was similar for the two treatments. Compared with FI, PRD treatment saved 30% water and increased crop water use efficiency (WUE) by 59%. Restrictions on leaf area expansion and g(s) by PRD-induced ABA signals might have contributed to reduced water use and increased WUE.

  2. Transcriptional regulation of 9-cis-epoxycarotenoid dioxygenase (NCED) gene by putrescine accumulation positively modulates ABA synthesis and drought tolerance in Lotus tenuis plants.

    PubMed

    Espasandin, Fabiana D; Maiale, Santiago J; Calzadilla, Pablo; Ruiz, Oscar A; Sansberro, Pedro A

    2014-03-01

    The accumulation of putrescine (Put) and increased arginine decarboxylase (ADC, EC 4.1.1.19) activity levels in response to osmotic stress has been reported; however, the biological meaning of this increase remains unclear. To obtain new insights into these questions, we studied the drought response of a transgenic Lotus tenuis line that expresses the oat ADC gene, which is driven by the stress-inducible pRD29A promoter. This line contains high levels of Put with no changes in spermidine and spermine contents, even under water deficits. Our results indicate that the biochemical and morphological responses to dehydration correlate with the Put level and provide evidence that Put controls the ABA content in response to drought by modulating ABA biosynthesis at the transcriptional level.

  3. Overexpression of an ABA biosynthesis gene using a stress-inducible promoter enhances drought resistance in petunia.

    PubMed

    Estrada-Melo, Alejandro C; Chao; Reid, Michael S; Jiang, Cai-Zhong

    2015-01-01

    The response of plants to drought stress includes reduced transpiration as stomates close in response to increased abscisic acid (ABA) concentrations. Constitutive overexpression of 9-cis-epoxycarotenoid dioxygenase (NCED), a key enzyme in ABA biosynthesis, increases drought resistance, but causes negative pleiotropic effects on plant growth and development. We overexpressed the tomato NCED (LeNCED1) in petunia plants under the control of a stress-inducible promoter, rd29A. Under water stress, the transgenic plants had increased transcripts of NCED mRNA, elevated leaf ABA concentrations, increased concentrations of proline, and a significant increase in drought resistance. The transgenic plants also displayed the expected decreases in stomatal conductance, transpiration, and photosynthesis. After 14 days without water, the control plants were dead, but the transgenic plants, though wilted, recovered fully when re-watered. Well-watered transgenic plants grew like non-transformed control plants and there was no effect of the transgene on seed dormancy.

  4. Overexpression of an ABA biosynthesis gene using a stress-inducible promoter enhances drought resistance in petunia

    PubMed Central

    Estrada-Melo, Alejandro C; Chao; Reid, Michael S; Jiang, Cai-Zhong

    2015-01-01

    The response of plants to drought stress includes reduced transpiration as stomates close in response to increased abscisic acid (ABA) concentrations. Constitutive overexpression of 9-cis-epoxycarotenoid dioxygenase (NCED), a key enzyme in ABA biosynthesis, increases drought resistance, but causes negative pleiotropic effects on plant growth and development. We overexpressed the tomato NCED (LeNCED1) in petunia plants under the control of a stress-inducible promoter, rd29A. Under water stress, the transgenic plants had increased transcripts of NCED mRNA, elevated leaf ABA concentrations, increased concentrations of proline, and a significant increase in drought resistance. The transgenic plants also displayed the expected decreases in stomatal conductance, transpiration, and photosynthesis. After 14 days without water, the control plants were dead, but the transgenic plants, though wilted, recovered fully when re-watered. Well-watered transgenic plants grew like non-transformed control plants and there was no effect of the transgene on seed dormancy. PMID:26504568

  5. Overexpression of Arabidopsis translationally controlled tumor protein gene AtTCTP enhances drought tolerance with rapid ABA-induced stomatal closure.

    PubMed

    Kim, Yong-Min; Han, Yun-Jeong; Hwang, Ok-Jin; Lee, Si-Seok; Shin, Ah-Young; Kim, Soo Young; Kim, Jeong-Il

    2012-06-01

    Translationally controlled tumor protein (TCTP), also termed P23 in human, belongs to a family of calcium- and tubulin-binding proteins, and it is generally regarded as a growth-regulating protein. Recently, Arabidopsis TCTP (AtTCTP) has been reported to function as an important growth regulator in plants. On the other hand, plant TCTP has been suggested to be involved in abiotic stress signaling such as aluminum, salt, and water deficit by a number of microarray or proteomic analyses. In this study, the biological functions of AtTCTP were investigated by using transgenic Arabidopsis plants overexpressing AtTCTP. Interestingly, AtTCTP overexpression enhanced drought tolerance in plants. The expression analysis showed that AtTCTP was expressed in guard cells as well as in actively growing tissues. Physiological studies of the overexpression lines showed increased ABA- and calcium-induced stomatal closure ratios and faster stomatal closing responses to ABA. Furthermore, in vitro protein-protein interaction analysis confirmed the interaction between AtTCTP and microtubules, and microtubule cosedimentation assays revealed that the microtubule binding of AtTCTP increased after calcium treatment. These results demonstrate that the overexpression of AtTCTP confers drought tolerance to plants by rapid ABA-mediated stomatal closure via the interaction with microtubules in which calcium binding enhances the interaction. Collectively, the present results suggest that the plant TCTP has molecular properties similar to animal TCTPs, such as tubulin- and calcium-binding, and that it functions in ABA-mediated stomatal movement, in addition to regulating the growth of plants.

  6. GsAPK, an ABA-activated and calcium-independent SnRK2-type kinase from G. soja, mediates the regulation of plant tolerance to salinity and ABA stress.

    PubMed

    Yang, Liang; Ji, Wei; Gao, Peng; Li, Yong; Cai, Hua; Bai, Xi; Chen, Qin; Zhu, Yanming

    2012-01-01

    Plant Snf1 (sucrose non-fermenting-1) related protein kinase (SnRK), a subfamily of serine/threonine kinases, has been implicated as a crucial upstream regulator of ABA and osmotic signaling as in many other signaling cascades. In this paper, we have isolated a novel plant specific ABA activated calcium independent protein kinase (GsAPK) from a highly salt tolerant plant, Glycine soja (50109), which is a member of the SnRK2 family. Subcellular localization studies using GFP fusion protein indicated that GsAPK is localized in the plasma membrane. We found that autophosphorylation and Myelin Basis Protein phosphorylation activity of GsAPK is only activated by ABA and the kinase activity also was observed when calcium was replaced by EGTA, suggesting its independence of calcium in enzyme activity. We also found that cold, salinity, drought, and ABA stress alter GsAPK gene transcripts and heterogonous overexpression of GsAPK in Arabidopsis alters plant tolerance to high salinity and ABA stress. In summary, we demonstrated that GsAPK is a Glycine soja ABA activated calcium independent SnRK-type kinase presumably involved in ABA mediated stress signal transduction.

  7. Chemical inhibition of potato ABA-8'-hydroxylase activity alters in vitro and in vivo ABA metabolism and endogenous ABA levels but does not affect potato microtuber dormancy duration.

    PubMed

    Suttle, Jeffrey C; Abrams, Suzanne R; De Stefano-Beltrán, Luis; Huckle, Linda L

    2012-09-01

    The effects of azole-type P450 inhibitors and two metabolism-resistant abscisic acid (ABA) analogues on in vitro ABA-8'-hydroxylase activity, in planta ABA metabolism, endogenous ABA content, and tuber meristem dormancy duration were examined in potato (Solanum tuberosum L. cv. Russet Burbank). When functionally expressed in yeast, three potato CYP707A genes were demonstrated to encode enzymatically active ABA-8'-hydroxylases with micromolar affinities for (+)-ABA. The in vitro activity of the three enzymes was inhibited by the P450 azole-type inhibitors ancymidol, paclobutrazol, diniconazole, and tetcyclasis, and by the 8'-acetylene- and 8'-methylene-ABA analogues, with diniconazole and tetcyclasis being the most potent inhibitors. The in planta metabolism of [(3)H](±)-ABA to phaseic acid and dihydrophaseic acid in tuber meristems was inhibited by diniconazole, tetcyclasis, and to a lesser extent by 8'-acetylene- and 8'-methylene-ABA. Continuous exposure of in vitro generated microtubers to diniconazole resulted in a 2-fold increase in endogenous ABA content and a decline in dihydrophaseic acid content after 9 weeks of development. Similar treatment with 8'-acetylene-ABA had no effects on the endogenous contents of ABA or phaseic acid but reduced the content of dihydrophaseic acid. Tuber meristem dormancy progression was determined ex vitro in control, diniconazole-, and 8'-acetylene-ABA-treated microtubers following harvest. Continuous exposure to diniconazole during microtuber development had no effects on subsequent sprouting at any time point. Continuous exposure to 8'-acetylene-ABA significantly increased the rate of microtuber sprouting. The results indicate that, although a decrease in ABA content is a hallmark of tuber dormancy progression, the decline in ABA levels is not a prerequisite for dormancy exit and the onset of tuber sprouting.

  8. StCDPK3 Phosphorylates In Vitro Two Transcription Factors Involved in GA and ABA Signaling in Potato: StRSG1 and StABF1

    PubMed Central

    Grandellis, Carolina; Fantino, Elisa; Muñiz García, María Noelia; Bialer, Magalí Graciela; Santin, Franco; Capiati, Daniela Andrea; Ulloa, Rita María

    2016-01-01

    Calcium-dependent protein kinases, CDPKs, decode calcium (Ca2+) transients and initiate downstream responses in plants. In order to understand how CDPKs affect plant physiology, their specific target proteins must be identified. In tobacco, the bZIP transcription factor Repression of Shoot Growth (NtRSG) that modulates gibberellin (GA) content is a specific target of NtCDPK1. StCDPK3 from potato is homologous (88% identical) to NtCDPK1 even in its N-terminal variable domain. In this work, we observe that NtRSG is also phosphorylated by StCDPK3. The potato RSG family of transcription factors is composed of three members that share similar features. The closest homologue to NtRSG, which was named StRSG1, was amplified and sequenced. qRT-PCR data indicate that StRSG1 is mainly expressed in petioles, stems, lateral buds, and roots. In addition, GA treatment affected StRSG1 expression. StCDPK3 transcripts were detected in leaves, petioles, stolons, roots, and dormant tubers, and transcript levels were modified in response to GA. The recombinant StRSG1-GST protein was produced and tested as a substrate for StCDPK3 and StCDPK1. 6xHisStCDPK3 was able to phosphorylate the potato StRSG1 in a Ca2+-dependent way, while 6xHisStCDPK1 could not. StCDPK3 also interacts and phosphorylates the transcription factor StABF1 (ABRE binding factor 1) involved in ABA signaling, as shown by EMSA and phosphorylation assays. StABF1 transcripts were mainly detected in roots, stems, and stolons. Our data suggest that StCDPK3 could be involved in the cross-talk between ABA and GA signaling at the onset of tuber development. PMID:27907086

  9. Nitric oxide modulates sensitivity to ABA

    PubMed Central

    Lozano-Juste, Jorge

    2010-01-01

    Nitric oxide (NO) is a gas with crucial signaling functions in plant defense and development. As demonstrated by generating a triple nia1nia2noa1-2 mutant with extremely low levels of NO (February 2010 issue of Plant Physiology), NO is synthesized in plants through mainly two different pathways involving nitrate reductase (NR/NIA) and NO Associated 1 (AtNOA1) proteins. Depletion of basal NO levels leads to a priming of ABA-triggered responses that causes hypersensitivity to this hormone and results in enhanced seed dormancy and decreased seed germination and seedling establishment in the triple mutant. NO produced under non-stressed conditions represses inhibition of seed developmental transitions by ABA. Moreover, NO plays a positive role in post-germinative vegetative development and also exerts a critical control of ABA-related functions on stomata closure. The triple nia1nia2noa1-2 mutant is hypersensitive to ABA in stomatal closure thus resulting in a extreme phenotype of resistance to drought. In the light of the recent discovery of PYR/PYL/RCAR as a family of potential ABA receptors, regulation of ABA sensitivity by NO may be exerted either directly on ABA receptors or on downstream signalling components; both two aspects that deserve our present and future attention. PMID:20168082

  10. Sucrose and ABA regulate starch biosynthesis in maize through a novel transcription factor, ZmEREB156

    PubMed Central

    Huang, Huanhuan; Xie, Sidi; Xiao, Qianlin; Wei, Bin; Zheng, Lanjie; Wang, Yongbin; Cao, Yao; Zhang, Xiangge; Long, Tiandan; Li, Yangping; Hu, Yufeng; Yu, Guowu; Liu, Hanmei; Liu, Yinghong; Huang, Zhi; Zhang, Junjie; Huang, Yubi

    2016-01-01

    Sucrose is not only the carbon source for starch synthesis, but also a signal molecule. Alone or in coordination with ABA, it can regulate the expression of genes involved in starch synthesis. To investigate the molecular mechanisms underlying this effect, maize endosperms were collected from Zea mays L. B73 inbred line 10 d after pollination and treated with sucrose, ABA, or sucrose plus ABA at 28 °C in the dark for 24 h. RNA-sequence analysis of the maize endosperm transcriptome revealed 47 candidate transcription factors among the differentially expressed genes. We therefore speculate that starch synthetic gene expression is regulated by transcription factors induced by the combination of sucrose and ABA. ZmEREB156, a candidate transcription factor, is induced by sucrose plus ABA and is involved in starch biosynthesis. The ZmEREB156-GFP-fused protein was localized in the nuclei of onion epidermal cells, and ZmEREB156 protein possessed strong transcriptional activation activity. Promoter activity of the starch-related genes Zmsh2 and ZmSSIIIa increased after overexpression of ZmEREB156 in maize endosperm. ZmEREB156 could bind to the ZmSSIIIa promoter but not the Zmsh2 promoter in a yeast one-hybrid system. Thus, ZmEREB156 positively modulates starch biosynthetic gene ZmSSIIIa via the synergistic effect of sucrose and ABA. PMID:27282997

  11. Sequence analysis of expressed sequence tags from an ABA-treated cDNA library identifies stress response genes in the moss Physcomitrella patens.

    PubMed

    Machuka, J; Bashiardes, S; Ruben, E; Spooner, K; Cuming, A; Knight, C; Cove, D

    1999-04-01

    Partial cDNA sequencing was used to obtain 169 expressed sequence tags (ESTs) in the moss, Physcomitrella patens. The source of ESTs was a random cDNA library constructed from 7 day-old protonemata following treatment with 10(-4) M abscisic acid (ABA). Analysis of the ESTs identified 69% with homology to known sequences, 61% of which had significant homology to sequences of plant origin. More importantly, at least 11 ESTs had significant similarities to genes which are implicated in plant stress-responses, including responses which may involve ABA. These included a cDNA associated with desiccation tolerance, two heat shock protein genes, one cold acclimation protein cDNA and five others that may be involved in either oxidative or chemical stress or both, i.e., Zn/Cu-superoxide dismutase, NADPH protochlorophyllide oxidoreductase (PorB), selenium binding protein, glutathione peroxidase and glutathione S transferase. Analysis of codon usage between P. patens and seed plants indicated that although mosses and higher plants are to a large extent similar, minor variations also exists that may represent the distinctiveness of each group.

  12. Abscisic acid interacts antagonistically with salicylic acid signaling pathway in rice-Magnaporthe grisea interaction.

    PubMed

    Jiang, Chang-Jie; Shimono, Masaki; Sugano, Shoji; Kojima, Mikiko; Yazawa, Katsumi; Yoshida, Riichiro; Inoue, Haruhiko; Hayashi, Nagao; Sakakibara, Hitoshi; Takatsuji, Hiroshi

    2010-06-01

    Plant hormones play pivotal signaling roles in plant-pathogen interactions. Here, we report characterization of an antagonistic interaction of abscisic acid (ABA) with salicylic acid (SA) signaling pathways in the rice-Magnaporthe grisea interaction. Exogenous application of ABA drastically compromised the rice resistance to both compatible and incompatible M. grisea strains, indicating that ABA negatively regulates both basal and resistance gene-mediated blast resistance. ABA markedly suppressed the transcriptional upregulation of WRKY45 and OsNPR1, the two key components of the SA signaling pathway in rice, induced by SA or benzothiadiazole or by blast infection. Overexpression of OsNPR1 or WRKY45 largely negated the enhancement of blast susceptibility by ABA, suggesting that ABA acts upstream of WRKY45 and OsNPR1 in the rice SA pathway. ABA-responsive genes were induced during blast infection in a pattern reciprocal to those of WRKY45 and OsPR1b in the compatible rice-blast interaction but only marginally in the incompatible one. These results suggest that the balance of SA and ABA signaling is an important determinant for the outcome of the rice-M. grisea interaction. ABA was detected in hyphae and conidia of M. grisea as well as in culture media, implying that blast-fungus-derived ABA could play a role in triggering ABA signaling at host infection sites.

  13. Identification of OsbZIP72 as a positive regulator of ABA response and drought tolerance in rice.

    PubMed

    Lu, Guojun; Gao, Chenxi; Zheng, Xingnan; Han, Bin

    2009-02-01

    Abscisic Acid (ABA) is an important phytohormone involved in abiotic stress resistance in plants. A group of bZIP transcription factors play important roles in the ABA signaling pathway in Arabidopsis. However, little is known about the function of their orthologs in rice, where they may hold a great potential for developing drought resistant food crops. In this study, our phylogenetic analysis showed that this group of bZIPs was evolutionarily conserved between Arabidopsis and rice, which implies that they may share similar functions. We demonstrated with quantitative RT-PCR that the expressions of most of these OsbZIPs were significantly induced by ABA, ACC, and abiotic stresses. OsbZIP72, a member of this group, was proved to be an ABRE binding factor in rice using the yeast hybrid systems. We showed that it could bind to ABRE and transactivate the downstream reporter genes in yeast, and the transactivity was depending on its N-terminal region. Transgenic rice overexpressing OsbZIP72 showed a hypersensitivity to ABA, elevated levels of expression of ABA response gene such as LEAs, and an enhanced ability of drought tolerance. These results suggest that OsbZIP72 plays a positive role in drought resistance through ABA signaling, and is potential useful for engineering drought tolerant rice.

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

    PubMed

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

    2013-10-01

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

  15. Abscisic acid (ABA) regulates grape bud dormancy, and dormancy release stimuli may act through modification of ABA metabolism

    PubMed Central

    Zheng, Chuanlin; Halaly, Tamar; Acheampong, Atiako Kwame; Takebayashi, Yumiko; Jikumaru, Yusuke; Kamiya, Yuji; Or, Etti

    2015-01-01

    In warm-winter regions, induction of dormancy release by hydrogen cyanamide (HC) is mandatory for commercial table grape production. Induction of respiratory stress by HC leads to dormancy release via an uncharacterized biochemical cascade that could reveal the mechanism underlying this phenomenon. Previous studies proposed a central role for abscisic acid (ABA) in the repression of bud meristem activity, and suggested its removal as a critical step in the HC-induced cascade. In the current study, support for these assumptions was sought. The data show that ABA indeed inhibits dormancy release in grape (Vitis vinifera) buds and attenuates the advancing effect of HC. However, HC-dependent recovery was detected, and was affected by dormancy status. HC reduced VvXERICO and VvNCED transcript levels and induced levels of VvABA8’OH homologues. Regulation of these central players in ABA metabolism correlated with decreased ABA and increased ABA catabolite levels in HC-treated buds. Interestingly, an inhibitor of ethylene signalling attenuated these effects of HC on ABA metabolism. HC also modulated the expression of ABA signalling regulators, in a manner that supports a decreased ABA level and response. Taken together, the data support HC-induced removal of ABA-mediated repression via regulation of ABA metabolism and signalling. Expression profiling during the natural dormancy cycle revealed that at maximal dormancy, the HC-regulated VvNCED1 transcript level starts to drop. In parallel, levels of VvA8H-CYP707A4 transcript and ABA catabolites increase sharply. This may provide initial support for the involvement of ABA metabolism also in the execution of natural dormancy. PMID:25560179

  16. The AvrB_AvrC domain of AvrXccC of Xanthomonas campestris pv. campestris is required to elicit plant defense responses and manipulate ABA homeostasis.

    PubMed

    Ho, Yi-Ping; Tan, Choon Meng; Li, Meng-Ying; Lin, Hong; Deng, Wen-Ling; Yang, Jun-Yi

    2013-04-01

    Plant disease induced by Xanthomonas campestris pv. campestris depends on type III effectors but the molecular basis is poorly understood. Here, AvrXccC8004 was characterized, and it was found that the AvrB_AvrC domain was essential and sufficient to elicit defense responses in an Arabidopsis-resistant ecotype (Col-0). An upregulation of genes in responding to the AvrB_AvrC domain of AvrXccC8004 was shown in a profile of host gene expression. The molecular changes were correlated with morphological changes observed in phenotypic and ultrastructural characterizations. Interestingly, the abscisic acid (ABA)-signaling pathway was also a prominent target for the AvrB_AvrC domain of AvrXccC8004. The highly elicited NCED5, encoding a key enzyme of ABA biosynthesis, was increased in parallel with ABA levels in AvrXccC8004 transgenic plants. Consistently, the X. campestris pv. campestris 8004 ΔavrXccC mutant was severely impaired in the ability to manipulate the accumulation of ABA and induction of ABA-related genes in challenged leaves. Moreover, exogenous application of ABA also enhanced the susceptibility of Arabidopsis to the X. campestris pv. campestris strains. These results indicate that the AvrB_AvrC domain of AvrXccC8004 alone has the activity to manipulate ABA homeostasis, which plays an important role in regulating the interactions of X. campestris pv. campestris and Arabidopsis.

  17. Transcriptome profiling identifies ABA mediated regulatory changes towards storage filling in developing seeds of castor bean (Ricinus communis L.)

    PubMed Central

    2014-01-01

    Background The potential biodiesel plant castor bean (Ricinus communis) has been in the limelight for bioenergy research due to the availability of its genome which raises the bar for genome-wide studies claiming advances that impact the “genome-phenome challenge”. Here we report the application of phytohormone ABA as an exogenous factor for the improvement of storage reserve accumulation with a focus on the complex interaction of pathways associated with seed filling. Results After the application of exogenous ABA treatments, we measured an increased ABA levels in the developing seeds cultured in vitro using the ELISA technique and quantified the content of major biomolecules (including total lipids, sugars and protein) in treated seeds. Exogenous ABA (10 μM) enhanced the accumulation of soluble sugar content (6.3%) followed by deposition of total lipid content (4.9 %). To elucidate the possible ABA signal transduction pathways towards overall seed filling, we studied the differential gene expression analysis using Illumina RNA-Sequencing technology, resulting in 2568 (1507-up/1061-down regulated) differentially expressed genes were identified. These genes were involved in sugar metabolism (such as glucose-6-phosphate, fructose 1,6 bis-phosphate, glycerol-3-phosphate, pyruvate kinase), lipid biosynthesis (such as ACS, ACBP, GPAT2, GPAT3, FAD2, FAD3, SAD1 and DGAT1), storage proteins synthesis (such as SGP1, zinc finger protein, RING H2 protein, nodulin 55 and cytochrome P450), and ABA biosynthesis (such as NCED1, NCED3 and beta carotene). Further, we confirmed the validation of RNA-Sequencing data by Semi-quantitative RT-PCR analysis. Conclusions Taken together, metabolite measurements supported by genes and pathway expression results indicated in this study provide new insights to understand the ABA signaling mechanism towards seed storage filling and also contribute useful information for facilitating oilseed crop functional genomics on an aim for utilizing

  18. Grafting cucumber onto luffa improves drought tolerance by increasing ABA biosynthesis and sensitivity

    PubMed Central

    Liu, Shanshan; Li, Hao; Lv, Xiangzhang; Ahammed, Golam Jalal; Xia, Xiaojian; Zhou, Jie; Shi, Kai; Asami, Tadao; Yu, Jingquan; Zhou, Yanhong

    2016-01-01

    Balancing stomata-dependent CO2 assimilation and transpiration is a key challenge for increasing crop productivity and water use efficiency under drought stress for sustainable crop production worldwide. Here, we show that cucumber and luffa plants with luffa as rootstock have intrinsically increased water use efficiency, decreased transpiration rate and less affected CO2 assimilation capacity following drought stress over those with cucumber as rootstock. Drought accelerated abscisic acid (ABA) accumulation in roots, xylem sap and leaves, and induced the transcript of ABA signaling genes, leading to a decreased stomatal aperture and transpiration in the plants grafted onto luffa roots as compared to plants grafted onto cucumber roots. Furthermore, stomatal movement in the plants grafted onto luffa roots had an increased sensitivity to ABA. Inhibition of ABA biosynthesis in luffa roots decreased the drought tolerance in cucumber and luffa plants. Our study demonstrates that the roots of luffa have developed an enhanced ability to sense the changes in root-zone moisture and could eventually deliver modest level of ABA from roots to shoots that enhances water use efficiency under drought stress. Such a mechanism could be greatly exploited to benefit the agricultural production especially in arid and semi-arid areas. PMID:26832070

  19. Isolation and Characterization of ScGluD2, a New Sugarcane beta-1,3-Glucanase D Family Gene Induced by Sporisorium scitamineum, ABA, H2O2, NaCl, and CdCl2 Stresses

    PubMed Central

    Su, Yachun; Wang, Zhuqing; Liu, Feng; Li, Zhu; Peng, Qiong; Guo, Jinlong; Xu, Liping; Que, Youxiong

    2016-01-01

    Beta-1,3-glucanases (EC 3.2.1.39), commonly known as pathogenesis-related (PR) proteins, play an important role not only in plant defense against fungal pathogens but also in plant physiological and developmental processes. However, only a limited number of sugarcane beta-1,3-glucanase genes have been isolated. In the present study, we identified and characterized a new beta-1,3-glucanase gene ScGluD2 (GenBank Acc No. KF664181) from sugarcane. An X8 domain was present at the C terminal region of ScGluD2, suggesting beta-1,3-glucan-binding function. Phylogenetic analysis showed that the predicted ScGluD2 protein was classified into subfamily D beta-1,3-glucanase. Localization of the ScGluD2 protein in the plasma membrane was determined by tagging it with green fluorescent protein. The expression of ScGluD2 was more up-regulated in sugarcane smut-resistant cultivars in the early stage (1 or 3 days) than in the susceptible ones after being challenged by the smut pathogen, revealing that ScGluD2 may be involved in defense against the invasion of Sporisorium scitamineum. Transient overexpression of ScGluD2 in Nicotiana benthamiana leaves induced a defense response and exhibited antimicrobial action on the tobacco pathogens Pseudomonas solanacearum and Botrytis cinerea, further demonstrating that ScGluD2 was related to the resistance to plant pathogens. However, the transcripts of ScGluD2 partially increased (12 h) under NaCl stress, and were steadily up-regulated from 6 to 24 h upon ABA, H2O2, and CdCl2 treatments, suggesting that ABA may be a signal molecule regulating oxidative stress and play a role in the salt and heavy metal stress-induced stimulation of ScGluD2 transcripts. Taken together, ScGluD2, a novel member of subfamily D beta-1,3-glucanase, was a stress-related gene of sugarcane involved in plant defense against smut pathogen attack and salt and heavy metal stresses. PMID:27642288

  20. A NAP-AAO3 regulatory module promotes chlorophyll degradation via ABA biosynthesis in Arabidopsis leaves.

    PubMed

    Yang, Jiading; Worley, Eric; Udvardi, Michael

    2014-12-01

    Chlorophyll degradation is an important part of leaf senescence, but the underlying regulatory mechanisms are largely unknown. Excised leaves of an Arabidopsis thaliana NAC-LIKE, ACTIVATED BY AP3/PI (NAP) transcription factor mutant (nap) exhibited lower transcript levels of known chlorophyll degradation genes, STAY-GREEN1 (SGR1), NON-YELLOW COLORING1 (NYC1), PHEOPHYTINASE (PPH), and PHEIDE a OXYGENASE (PaO), and higher chlorophyll retention than the wild type during dark-induced senescence. Transcriptome coexpression analysis revealed that abscisic acid (ABA) metabolism/signaling genes were disproportionately represented among those positively correlated with NAP expression. ABA levels were abnormally low in nap leaves during extended darkness. The ABA biosynthetic genes 9-CIS-EPOXYCAROTENOID DIOXYGENASE2, ABA DEFICIENT3, and ABSCISIC ALDEHYDE OXIDASE3 (AAO3) exhibited abnormally low transcript levels in dark-treated nap leaves. NAP transactivated the promoter of AAO3 in mesophyll cell protoplasts, and electrophoretic mobility shift assays showed that NAP can bind directly to a segment (-196 to -162 relative to the ATG start codon) of the AAO3 promoter. Exogenous application of ABA increased the transcript levels of SGR1, NYC1, PPH, and PaO and suppressed the stay-green phenotype of nap leaves during extended darkness. Overexpression of AAO3 in nap leaves also suppressed the stay-green phenotype under extended darkness. Collectively, the results show that NAP promotes chlorophyll degradation by enhancing transcription of AAO3, which leads to increased levels of the senescence-inducing hormone ABA.

  1. Dissecting Abscisic Acid Signaling Pathways Involved in Cuticle Formation.

    PubMed

    Cui, Fuqiang; Brosché, Mikael; Lehtonen, Mikko T; Amiryousefi, Ali; Xu, Enjun; Punkkinen, Matleena; Valkonen, Jari P T; Fujii, Hiroaki; Overmyer, Kirk

    2016-06-06

    The cuticle is the outer physical barrier of aerial plant surfaces and an important interaction point between plants and the environment. Many environmental stresses affect cuticle formation, yet the regulatory pathways involved remain undefined. We used a genetics and gene expression analysis in Arabidopsis thaliana to define an abscisic acid (ABA) signaling loop that positively regulates cuticle formation via the core ABA signaling pathway, including the PYR/PYL receptors, PP2C phosphatase, and SNF1-Related Protein Kinase (SnRK) 2.2/SnRK2.3/SnRK2.6. Downstream of the SnRK2 kinases, cuticle formation was not regulated by the ABA-responsive element-binding transcription factors but rather by DEWAX, MYB16, MYB94, and MYB96. Additionally, low air humidity increased cuticle formation independent of the core ABA pathway and cell death/reactive oxygen species signaling attenuated expression of cuticle-biosynthesis genes. In Physcomitrella patens, exogenous ABA suppressed expression of cuticle-related genes, whose Arabidopsis orthologs were ABA-induced. Hence, the mechanisms regulating cuticle formation are conserved but sophisticated in land plants. Signaling specifically related to cuticle deficiency was identified to play a major role in the adaptation of ABA signaling pathway mutants to increased humidity and in modulating their immunity to Botrytis cinerea in Arabidopsis. These results define a cuticle-specific downstream branch in the ABA signaling pathway that regulates responses to the external environment.

  2. Hormone profiling and transcription analysis reveal a major role of ABA in tomato salt tolerance.

    PubMed

    Yang, Rongchao; Yang, Ting; Zhang, Haijun; Qi, Yan; Xing, Yanxia; Zhang, Na; Li, Ren; Weeda, Sarah; Ren, Shuxin; Ouyang, Bo; Guo, Yang-Dong

    2014-04-01

    The response and adaptation of plants to different environmental stresses are of great interest as they provide the key to understanding the mechanisms underlying stress tolerance. In this study, the changing patterns of four endogenous hormones and various physiological and biochemical parameters of both a salt-tolerant (LA2711) and a salt-sensitive (ZS-5) tomato cultivar were examined under salt stress and non-stress conditions. Additionally, the transcription of key genes in the abscisic acid (ABA) biosynthesis and metabolism were analyzed at different time points. The results indicated that gene expression responsible for ABA biosynthesis and metabolism coincided with the hormone level, and SlNCED1 and SlCYP707A3 may play major roles in the process. LA2711 performed superior to ZS-5 on various parameters, including seed germination, Na(+) compartmentation, selective absorption of K(+), and antioxidant enzymes activity. The difference in salt tolerance between the two genotypes could be attributed to the different levels of ABA due to differences in gene expression of key genes in ABA biosynthesis and metabolism. Although gibberellin, cytokinin and auxin were involved, our results indicated that ABA signaling plays a major role in tomato salt tolerance. As compared to ZS-5, LA2711 had a higher capability to selectively absorb and redistribute K(+) and a higher tolerance to Na(+) in young leaves, which may be the main physiological mechanisms of salt tolerance.

  3. Abscisic acid metabolizing rhizobacteria decrease ABA concentrations in planta and alter plant growth.

    PubMed

    Belimov, Andrey A; Dodd, Ian C; Safronova, Vera I; Dumova, Valentina A; Shaposhnikov, Alexander I; Ladatko, Alexander G; Davies, William J

    2014-01-01

    Although endogenous phytohormones such as abscisic acid (ABA) regulate root growth, and many rhizobacteria can modulate root phytohormone status, hitherto there have been no reports of rhizobacteria mediating root ABA concentrations and growth by metabolising ABA. Using a selective ABA-supplemented medium, two bacterial strains were isolated from the rhizosphere of rice (Oryza sativa) seedlings grown in sod-podzolic soil and assigned to Rhodococcus sp. P1Y and Novosphingobium sp. P6W using partial 16S rRNA gene sequencing and phenotypic patterns by the GEN III MicroPlate test. Although strain P6W had more rapid growth in ABA-supplemented media than strain P1Y, both could utilize ABA as a sole carbon source in batch culture. When rice seeds were germinated on filter paper in association with bacteria, root ABA concentration was not affected, but shoot ABA concentration of inoculated plants decreased by 14% (strain P6W) and 22% (strain P1Y). When tomato (Solanum lycopersicum) genotypes differing in ABA biosynthesis (ABA deficient mutants flacca - flc, and notabilis - not and the wild-type cv. Ailsa Craig, WT) were grown in gnotobiotic cultures on nutrient solution agar, rhizobacterial inoculation decreased root and/or leaf ABA concentrations, depending on plant and bacteria genotypes. Strain P6W inhibited primary root elongation of all genotypes, but increased leaf biomass of WT plants. In WT plants treated with silver ions that inhibit ethylene perception, both ABA-metabolising strains significantly decreased root ABA concentration, and strain P6W decreased leaf ABA concentration. Since these changes in ABA status also occurred in plants that were not treated with silver, it suggests that ethylene was probably not involved in regulating bacteria-mediated changes in ABA concentration. Correlations between plant growth and ABA concentrations in planta suggest that ABA-metabolising rhizobacteria may stimulate growth via an ABA-dependent mechanism.

  4. ABA and cytokinins: challenge and opportunity for plant stress research.

    PubMed

    Verslues, Paul E

    2016-08-01

    Accumulation of the stress hormone abscisic acid (ABA) induces many cellular mechanisms associated with drought resistance. Recent years have seen a rapid advance in our knowledge of how increased ABA levels are perceived by ABA receptors, particularly the PYL/RCAR receptors, but there has been relatively less new information about how ABA accumulation is controlled and matched to stress severity. ABA synthesis and catabolism, conjugation and deconjugation to glucose, and ABA transport all are involved in controlling ABA levels. This highly buffered system of ABA metabolism represents both a challenge and opportunity in developing a mechanistic understanding of how plants detect and respond to drought. Recent data have also shown that direct manipulation of cytokinin levels in transgenic plants has dramatic effect on drought phenotypes and prompted new interest in the role of cytokinins and cytokinin signaling in drought. Both ABA and cytokinins will continue to be major foci of drought research but likely with different trajectories both in terms of basic research and in translational research aimed at increasing plant performance during drought.

  5. Disruption of abscisic acid signaling constitutively activates Arabidopsis resistance to the necrotrophic fungus Plectosphaerella cucumerina.

    PubMed

    Sánchez-Vallet, Andrea; López, Gemma; Ramos, Brisa; Delgado-Cerezo, Magdalena; Riviere, Marie-Pierre; Llorente, Francisco; Fernández, Paula Virginia; Miedes, Eva; Estevez, José Manuel; Grant, Murray; Molina, Antonio

    2012-12-01

    Plant resistance to necrotrophic fungi is regulated by a complex set of signaling pathways that includes those mediated by the hormones salicylic acid (SA), ethylene (ET), jasmonic acid (JA), and abscisic acid (ABA). The role of ABA in plant resistance remains controversial, as positive and negative regulatory functions have been described depending on the plant-pathogen interaction analyzed. Here, we show that ABA signaling negatively regulates Arabidopsis (Arabidopsis thaliana) resistance to the necrotrophic fungus Plectosphaerella cucumerina. Arabidopsis plants impaired in ABA biosynthesis, such as the aba1-6 mutant, or in ABA signaling, like the quadruple pyr/pyl mutant (pyr1pyl1pyl2pyl4), were more resistant to P. cucumerina than wild-type plants. In contrast, the hab1-1abi1-2abi2-2 mutant impaired in three phosphatases that negatively regulate ABA signaling displayed an enhanced susceptibility phenotype to this fungus. Comparative transcriptomic analyses of aba1-6 and wild-type plants revealed that the ABA pathway negatively regulates defense genes, many of which are controlled by the SA, JA, or ET pathway. In line with these data, we found that aba1-6 resistance to P. cucumerina was partially compromised when the SA, JA, or ET pathway was disrupted in this mutant. Additionally, in the aba1-6 plants, some genes encoding cell wall-related proteins were misregulated. Fourier transform infrared spectroscopy and biochemical analyses of cell walls from aba1-6 and wild-type plants revealed significant differences in their Fourier transform infrared spectratypes and uronic acid and cellulose contents. All these data suggest that ABA signaling has a complex function in Arabidopsis basal resistance, negatively regulating SA/JA/ET-mediated resistance to necrotrophic fungi.

  6. Chemical genetics reveals negative regulation of abscisic acid signaling by a plant immune response pathway.

    PubMed

    Kim, Tae-Houn; Hauser, Felix; Ha, Tracy; Xue, Shaowu; Böhmer, Maik; Nishimura, Noriyuki; Munemasa, Shintaro; Hubbard, Katharine; Peine, Nora; Lee, Byeong-Ha; Lee, Stephen; Robert, Nadia; Parker, Jane E; Schroeder, Julian I

    2011-06-07

    Coordinated regulation of protection mechanisms against environmental abiotic stress and pathogen attack is essential for plant adaptation and survival. Initial abiotic stress can interfere with disease-resistance signaling [1-6]. Conversely, initial plant immune signaling may interrupt subsequent abscisic acid (ABA) signal transduction [7, 8]. However, the processes involved in this crosstalk between these signaling networks have not been determined. By screening a 9600-compound chemical library, we identified a small molecule [5-(3,4-dichlorophenyl)furan-2-yl]-piperidine-1-ylmethanethione (DFPM) that rapidly downregulates ABA-dependent gene expression and also inhibits ABA-induced stomatal closure. Transcriptome analyses show that DFPM also stimulates expression of plant defense-related genes. Major early regulators of pathogen-resistance responses, including EDS1, PAD4, RAR1, and SGT1b, are required for DFPM-and notably also for Pseudomonas-interference with ABA signal transduction, whereas salicylic acid, EDS16, and NPR1 are not necessary. Although DFPM does not interfere with early ABA perception by PYR/RCAR receptors or ABA activation of SnRK2 kinases, it disrupts cytosolic Ca(2+) signaling and downstream anion channel activation in a PAD4-dependent manner. Our findings provide evidence that activation of EDS1/PAD4-dependent plant immune responses rapidly disrupts ABA signal transduction and that this occurs at the level of Ca(2+) signaling, illuminating how the initial biotic stress pathway interferes with ABA signaling.

  7. Cloning and expression of lipoxygenase genes and enzyme activity in ripening persimmon fruit in response to GA and ABA treatment

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Two genes of the lipoxygenase (LOX) family, DkLox1 and DkLox3 (GenBank accession No. JF436951 and JF436950), were cloned from persimmon fruit (Diospyros kaki L. ‘Fuping Jianshi’). Sequence analysis indicated that they belong to the 9-LOX sub-group. Heterologous expression of DkLox1 in E. coli produc...

  8. A 14-3-3 Family Protein from Wild Soybean (Glycine Soja) Regulates ABA Sensitivity in Arabidopsis.

    PubMed

    Sun, Xiaoli; Sun, Mingzhe; Jia, Bowei; Chen, Chao; Qin, Zhiwei; Yang, Kejun; Shen, Yang; Meiping, Zhang; Mingyang, Cong; Zhu, Yanming

    2015-01-01

    It is widely accepted that the 14-3-3 family proteins are key regulators of multiple stress signal transduction cascades. By conducting genome-wide analysis, researchers have identified the soybean 14-3-3 family proteins; however, until now, there is still no direct genetic evidence showing the involvement of soybean 14-3-3s in ABA responses. Hence, in this study, based on the latest Glycine max genome on Phytozome v10.3, we initially analyzed the evolutionary relationship, genome organization, gene structure and duplication, and three-dimensional structure of soybean 14-3-3 family proteins systematically. Our results suggested that soybean 14-3-3 family was highly evolutionary conserved and possessed segmental duplication in evolution. Then, based on our previous functional characterization of a Glycine soja 14-3-3 protein GsGF14o in drought stress responses, we further investigated the expression characteristics of GsGF14o in detail, and demonstrated its positive roles in ABA sensitivity. Quantitative real-time PCR analyses in Glycine soja seedlings and GUS activity assays in PGsGF14O:GUS transgenic Arabidopsis showed that GsGF14o expression was moderately and rapidly induced by ABA treatment. As expected, GsGF14o overexpression in Arabidopsis augmented the ABA inhibition of seed germination and seedling growth, promoted the ABA induced stomata closure, and up-regulated the expression levels of ABA induced genes. Moreover, through yeast two hybrid analyses, we further demonstrated that GsGF14o physically interacted with the AREB/ABF transcription factors in yeast cells. Taken together, results presented in this study strongly suggested that GsGF14o played an important role in regulation of ABA sensitivity in Arabidopsis.

  9. OsERF2 controls rice root growth and hormone responses through tuning expression of key genes involved in hormone signaling and sucrose metabolism.

    PubMed

    Xiao, Guiqing; Qin, Hua; Zhou, Jiahao; Quan, Ruidang; Lu, Xiangyang; Huang, Rongfeng; Zhang, Haiwen

    2016-02-01

    Root determines plant distribution, development progresses, stress response, as well as crop qualities and yields, which is under the tight control of genetic programs and environmental stimuli. Ethylene responsive factor proteins (ERFs) play important roles in plant growth and development. Here, the regulatory function of OsERF2 involved in root growth was investigated using the gain-function mutant of OsERF2 (nsf2857) and the artificial microRNA-mediated silenced lines of OsERF2 (Ami-OsERF2). nsf2857 showed short primary roots compared with the wild type (WT), while the primary roots of Ami-OsERF2 lines were longer than those of WT. Consistent with this phenotype, several auxin/cytokinin responsive genes involved in root growth were downregulated in nsf2857, but upregulated in Ami-OsERF2. Then, we found that nsf2857 seedlings exhibited decreased ABA accumulation and sensitivity to ABA and reduced ethylene-mediated root inhibition, while those were the opposite in Ami-ERF2 plants. Moreover, several key genes involved in ABA synthesis were downregulated in nsf2857, but unregulated in Ami-ERF2 lines. In addition, OsERF2 affected the accumulation of sucrose and UDPG by mediating expression of key genes involved in sucrose metabolism. These results indicate that OsERF2 is required for the control of root architecture and ABA- and ethylene-response by tuning expression of series genes involved in sugar metabolism and hormone signaling pathways.

  10. Disruption of Abscisic Acid Signaling Constitutively Activates Arabidopsis Resistance to the Necrotrophic Fungus Plectosphaerella cucumerina1[W

    PubMed Central

    Sánchez-Vallet, Andrea; López, Gemma; Ramos, Brisa; Delgado-Cerezo, Magdalena; Riviere, Marie-Pierre; Llorente, Francisco; Fernández, Paula Virginia; Miedes, Eva; Estevez, José Manuel; Grant, Murray; Molina, Antonio

    2012-01-01

    Plant resistance to necrotrophic fungi is regulated by a complex set of signaling pathways that includes those mediated by the hormones salicylic acid (SA), ethylene (ET), jasmonic acid (JA), and abscisic acid (ABA). The role of ABA in plant resistance remains controversial, as positive and negative regulatory functions have been described depending on the plant-pathogen interaction analyzed. Here, we show that ABA signaling negatively regulates Arabidopsis (Arabidopsis thaliana) resistance to the necrotrophic fungus Plectosphaerella cucumerina. Arabidopsis plants impaired in ABA biosynthesis, such as the aba1-6 mutant, or in ABA signaling, like the quadruple pyr/pyl mutant (pyr1pyl1pyl2pyl4), were more resistant to P. cucumerina than wild-type plants. In contrast, the hab1-1abi1-2abi2-2 mutant impaired in three phosphatases that negatively regulate ABA signaling displayed an enhanced susceptibility phenotype to this fungus. Comparative transcriptomic analyses of aba1-6 and wild-type plants revealed that the ABA pathway negatively regulates defense genes, many of which are controlled by the SA, JA, or ET pathway. In line with these data, we found that aba1-6 resistance to P. cucumerina was partially compromised when the SA, JA, or ET pathway was disrupted in this mutant. Additionally, in the aba1-6 plants, some genes encoding cell wall-related proteins were misregulated. Fourier transform infrared spectroscopy and biochemical analyses of cell walls from aba1-6 and wild-type plants revealed significant differences in their Fourier transform infrared spectratypes and uronic acid and cellulose contents. All these data suggest that ABA signaling has a complex function in Arabidopsis basal resistance, negatively regulating SA/JA/ET-mediated resistance to necrotrophic fungi. PMID:23037505

  11. Detection of Quorum Sensing Signal Molecules and Identification of an Autoinducer Synthase Gene among Biofilm Forming Clinical Isolates of Acinetobacter spp.

    PubMed Central

    Anbazhagan, Deepa; Mansor, Marzida; Yan, Gracie Ong Siok; Md Yusof, Mohd Yasim; Hassan, Hamimah; Sekaran, Shamala Devi

    2012-01-01

    Background Quorum sensing is a term that describes an environmental sensing system that allows bacteria to monitor their own population density which contributes significantly to the size and development of the biofilm. Many gram negative bacteria use N-acyl-homoserine lactones as quorum sensing signal molecules. In this study, we sought to find out if the biofilm formation among clinical isolates of Acinetobacter spp. is under the control of autoinducing quorum sensing molecules. Methodology/Principal Findings Biofilm formation among clinical isolates of Acinetobacter spp. was assessed and the production of signal molecules were detected with Chromobacterium violaceum CV026 biosensor system. Characterisation of autoinducers was carried out by mass spectrometric analysis. We have also reported the identification of an autoinducer synthase gene, abaΙ among the isolates that produce quorum sensing signal molecules and have reported that the mutation in the abaI gene influences their biofilm forming capabilities. Using a microtitre-plate assay it was shown that 60% of the 50 Acinetobacter spp. isolates significantly formed biofilms. Further detection with the biosensor strain showed that some of these isolates produced long chain signal molecules. Mass spectrometric analysis revealed that five of these isolates produced N-decanoyl homoserine lactone and two isolates produced acyl-homoserine lactone with a chain length equal to C12. The abaΙ gene was identified and a tetracycline mutant of the abaΙ gene was created and the inhibition in biofilm formation in the mutant was shown. Conclusions/Significance These data are of great significance as the signal molecules aid in biofilm formation which in turn confer various properties of pathogenicity to the clinical isolates including drug resistance. The use of quorum sensing signal blockers to attenuate bacterial pathogenicity is therefore highly attractive, particularly with respect to the emergence of multi antibiotic

  12. GsSKP21, a Glycine soja S-phase kinase-associated protein, mediates the regulation of plant alkaline tolerance and ABA sensitivity.

    PubMed

    Liu, Ailin; Yu, Yang; Duan, Xiangbo; Sun, Xiaoli; Duanmu, Huizi; Zhu, Yanming

    2015-01-01

    Plant SKP1-like family proteins, components of the SCF complex E3 ligases, are involved in the regulation of plant development and stress responses. Little is known about the precise function of SKP genes in plant responses to environmental stresses. GsSKP21 was initially identified as a potential stress-responsive gene based on the transcriptome sequencing of Glycine soja. In this study, we found that GsSKP21 protein contains highly conserved SKP domains in its N terminus and an extra unidentified domain in its C terminus. The transcript abundance of GsSKP21, detected by quantitative real-time PCR, was induced under the treatment of alkali and salt stresses. Overexpression of GsSKP21 in Arabidopsis dramatically increased plant tolerance to alkali stress. Furthermore, we found that overexpression of GsSKP21 resulted in decreased ABA sensitivity during both the seed germination and early seedling growth stages. GsSKP21 mediated ABA signaling by altering the expression levels of the ABA signaling-related and ABA-induced genes. We also investigated the tissue expression specificity and subcellular localization of GsSKP21. These results suggest that GsSKP21 is important for plant tolerance to alkali stress and plays a critical regulatory role in the ABA-mediated stress response.

  13. A balanced JA/ABA status may correlate with adaptation to osmotic stress in Vitis cells.

    PubMed

    Ismail, Ahmed; Seo, Mitsunori; Takebayashi, Yumiko; Kamiya, Yuji; Nick, Peter

    2015-08-01

    Water-related stress is considered a major type of plant stress. Osmotic stress, in particular, represents the common part of all water-related stresses. Therefore, plants have evolved different adaptive mechanisms to cope with osmotic-related disturbances. In the current work, two grapevine cell lines that differ in their osmotic adaptability, Vitis rupestris and Vitis riparia, were investigated under mannitol-induced osmotic stress. To dissect signals that lead to adaptability from those related to sensitivity, osmotic-triggered responses with respect to jasmonic acid (JA) and its active form JA-Ile, abscisic acid (ABA), and stilbene compounds, as well as the expression of their related genes were observed. In addition, the transcript levels of the cellular homeostasis gene NHX1 were examined. The data are discussed with a hypothesis suggesting that a balance of JA and ABA status might correlate with cellular responses, either guiding cells to sensitivity or to progress toward adaptation.

  14. An ABA-regulated and Golgi-localized protein phosphatase controls water loss during leaf senescence in Arabidopsis.

    PubMed

    Zhang, Kewei; Xia, Xiuying; Zhang, Yanyan; Gan, Su-Sheng

    2012-02-01

    It is known that a senescing leaf loses water faster than a non-senescing leaf and that ABA has an important role in promoting leaf senescence. However, questions such as why water loss is faster, how water loss is regulated, and how ABA functions in leaf senescence are not well understood. Here we report on the identification and functional analysis of a leaf senescence associated gene called SAG113. The RNA blot and GUS reporter analyses all show that SAG113 is expressed in senescing leaves and is induced by ABA in Arabidopsis. The SAG113 expression levels are significantly reduced in aba2 and abi4 mutants. A GFP fusion protein analysis revealed that SAG113 protein is localized in the Golgi apparatus. SAG113 encodes a protein phosphatase that belongs to the PP2C family and is able to functionally complement a yeast PP2C-deficient mutant TM126 (ptc1Δ). Leaf senescence is delayed in the SAG113 knockout mutant compared with that in the wild type, stomatal movement in the senescing leaves of SAG113 knockouts is more sensitive to ABA than that of the wild type, and the rate of water loss in senescing leaves of SAG113 knockouts is significantly reduced. In contrast, inducible over-expression of SAG113 results in a lower sensitivity of stomatal movement to ABA treatment, more rapid water loss, and precocious leaf senescence. No other aspects of growth and development, including seed germination, were observed. These findings suggest that SAG113, a negative regulator of ABA signal transduction, is specifically involved in the control of water loss during leaf senescence.

  15. A role for PacMYBA in ABA-regulated anthocyanin biosynthesis in red-colored sweet cherry cv. Hong Deng (Prunus avium L.).

    PubMed

    Shen, Xinjie; Zhao, Kai; Liu, Linlin; Zhang, Kaichun; Yuan, Huazhao; Liao, Xiong; Wang, Qi; Guo, Xinwei; Li, Fang; Li, Tianhong

    2014-05-01

    The MYB transcription factors and plant hormone ABA have been suggested to play a role in fruit anthocyanin biosynthesis, but supporting genetic evidence has been lacking in sweet cherry. The present study describes the first functional characterization of an R2R3-MYB transcription factor, PacMYBA, from red-colored sweet cherry cv. Hong Deng (Prunus avium L.). Transient promoter assays demonstrated that PacMYBA physically interacted with several anthocyanin-related basic helix-loop-helix (bHLH) transcription factors to activate the promoters of PacDFR, PacANS and PacUFGT, which are thought to be involved in anthocyanin biosynthesis. Furthermore, the immature seeds of transgenic Arabidopsis plants overexpressing PacMYBA exhibited ectopic pigmentation. Silencing of PacMYBA, using a Tobacco rattle virus (TRV)-induced gene silencing technique, resulted in sweet cherry fruit that lacked red pigment. ABA treatment significantly induced anthocyanin accumulation, while treatment with the ABA biosynthesis inhibitor nordihydroguaiaretic acid (NDGA) blocked anthocyanin production. PacMYBA expression peaked after 2 h of pre-incubation in ABA and was 15.2-fold higher than that of sweet cherries treated with NDGA. The colorless phenotype was also observed in the fruits silenced in PacNCED1, which encodes a key enzyme in the ABA biosynthesis pathway. The endogenous ABA content as well as the transcript levels of six structural genes and PacMYBA in PacNCED1-RNAi (RNA interference) fruit were significantly lower than in the TRV vector control fruit. These results suggest that PacMYBA plays an important role in ABA-regulated anthocyanin biosynthesis and ABA is a signal molecule that promotes red-colored sweet cherry fruit accumulating anthocyanin.

  16. ABA receptor PYL9 promotes drought resistance and leaf senescence.

    PubMed

    Zhao, Yang; Chan, Zhulong; Gao, Jinghui; Xing, Lu; Cao, Minjie; Yu, Chunmei; Hu, Yuanlei; You, Jun; Shi, Haitao; Zhu, Yingfang; Gong, Yuehua; Mu, Zixin; Wang, Haiqing; Deng, Xin; Wang, Pengcheng; Bressan, Ray A; Zhu, Jian-Kang

    2016-02-16

    Drought stress is an important environmental factor limiting plant productivity. In this study, we screened drought-resistant transgenic plants from 65 promoter-pyrabactin resistance 1-like (PYL) abscisic acid (ABA) receptor gene combinations and discovered that pRD29A::PYL9 transgenic lines showed dramatically increased drought resistance and drought-induced leaf senescence in both Arabidopsis and rice. Previous studies suggested that ABA promotes senescence by causing ethylene production. However, we found that ABA promotes leaf senescence in an ethylene-independent manner by activating sucrose nonfermenting 1-related protein kinase 2s (SnRK2s), which subsequently phosphorylate ABA-responsive element-binding factors (ABFs) and Related to ABA-Insensitive 3/VP1 (RAV1) transcription factors. The phosphorylated ABFs and RAV1 up-regulate the expression of senescence-associated genes, partly by up-regulating the expression of Oresara 1. The pyl9 and ABA-insensitive 1-1 single mutants, pyl8-1pyl9 double mutant, and snrk2.2/3/6 triple mutant showed reduced ABA-induced leaf senescence relative to the WT, whereas pRD29A::PYL9 transgenic plants showed enhanced ABA-induced leaf senescence. We found that leaf senescence may benefit drought resistance by helping to generate an osmotic potential gradient, which is increased in pRD29A::PYL9 transgenic plants and causes water to preferentially flow to developing tissues. Our results uncover the molecular mechanism of ABA-induced leaf senescence and suggest an important role of PYL9 and leaf senescence in promoting resistance to extreme drought stress.

  17. The Role and Regulation of ABI5 (ABA-Insensitive 5) in Plant Development, Abiotic Stress Responses and Phytohormone Crosstalk

    PubMed Central

    Skubacz, Anna; Daszkowska-Golec, Agata; Szarejko, Iwona

    2016-01-01

    ABA Insensitive 5 (ABI5) is a basic leucine zipper transcription factor that plays a key role in the regulation of seed germination and early seedling growth in the presence of ABA and abiotic stresses. ABI5 functions in the core ABA signaling, which is composed of PYR/PYL/RCAR receptors, PP2C phosphatases and SnRK2 kinases, through the regulation of the expression of genes that contain the ABSCISIC ACID RESPONSE ELEMENT (ABRE) motif within their promoter region. The regulated targets include stress adaptation genes, e.g., LEA proteins. However, the expression and activation of ABI5 is not only dependent on the core ABA signaling. Many transcription factors such as ABI3, ABI4, MYB7 and WRKYs play either a positive or a negative role in the regulation of ABI5 expression. Additionally, the stability and activity of ABI5 are also regulated by other proteins through post-translational modifications such as phosphorylation, ubiquitination, sumoylation and S-nitrosylation. Moreover, ABI5 also acts as an ABA and other phytohormone signaling integrator. Components of auxin, cytokinin, gibberellic acid, jasmonate and brassinosteroid signaling and metabolism pathways were shown to take part in ABI5 regulation and/or to be regulated by ABI5. Monocot orthologs of AtABI5 have been identified. Although their roles in the molecular and physiological adaptations during abiotic stress have been elucidated, knowledge about their detailed action still remains elusive. Here, we describe the recent advances in understanding the action of ABI5 in early developmental processes and the adaptation of plants to unfavorable environmental conditions. We also focus on ABI5 relation to other phytohormones in the abiotic stress response of plants. PMID:28018412

  18. Does PtaRHE1, a poplar RING-H2 protein, play a role in water conduction through ABA signaling?

    PubMed Central

    Moussawi, Jihad; Baldacci-Cresp, Fabien; El Jaziri, Mondher; Baucher, Marie

    2014-01-01

    RING (REALLY INTERESTING NEW GENE) proteins with E3 ligase activity are largely represented in plants. They have been shown to play important roles in the regulation of many biological processes by recognizing target proteins for ubiquitination. PtaRHE1, encoding a poplar RING-H2 domain-containing protein with E3 ligase activity has been previously shown to be expressed during the establishment of secondary vascular system in poplar. In the present report, we demonstrate that the expression of PtaRHE1 and the accumulation of its corresponding protein are modulated by the relative atmospheric and soil humidity and by abscisic acid. Overall, the integrated data are discussed within a working model highlighting a plausible function of PtaRHE1 in the signaling and/or in the regulation of water status in poplar. PMID:24393707

  19. FERONIA interacts with ABI2-type phosphatases to facilitate signaling cross-talk between abscisic acid and RALF peptide in Arabidopsis

    PubMed Central

    Chen, Jia; Yu, Feng; Liu, Ying; Du, Changqing; Li, Xiushan; Zhu, Sirui; Wang, Xianchun; Lan, Wenzhi; Rodriguez, Pedro L.; Liu, Xuanming; Li, Dongping; Chen, Liangbi; Luan, Sheng

    2016-01-01

    Receptor-like kinase FERONIA (FER) plays a crucial role in plant response to small molecule hormones [e.g., auxin and abscisic acid (ABA)] and peptide signals [e.g., rapid alkalinization factor (RALF)]. It remains unknown how FER integrates these different signaling events in the control of cell growth and stress responses. Under stress conditions, increased levels of ABA will inhibit cell elongation in the roots. In our previous work, we have shown that FER, through activation of the guanine nucleotide exchange factor 1 (GEF1)/4/10-Rho of Plant 11 (ROP11) pathway, enhances the activity of the phosphatase ABA Insensitive 2 (ABI2), a negative regulator of ABA signaling, thereby inhibiting ABA response. In this study, we found that both RALF and ABA activated FER by increasing the phosphorylation level of FER. The FER loss-of-function mutant displayed strong hypersensitivity to both ABA and abiotic stresses such as salt and cold conditions, indicating that FER plays a key role in ABA and stress responses. We further showed that ABI2 directly interacted with and dephosphorylated FER, leading to inhibition of FER activity. Several other ABI2-like phosphatases also function in this pathway, and ABA-dependent FER activation required PYRABACTIN RESISTANCE (PYR)/PYR1-LIKE (PYL)/REGULATORY COMPONENTS OF ABA RECEPTORS (RCAR)–A-type protein phosphatase type 2C (PP2CA) modules. Furthermore, suppression of RALF1 gene expression, similar to disruption of the FER gene, rendered plants hypersensitive to ABA. These results formulated a mechanism for ABA activation of FER and for cross-talk between ABA and peptide hormone RALF in the control of plant growth and responses to stress signals. PMID:27566404

  20. Reduced Accumulation of ABA during Water Stress in a Molybdenum Cofactor Mutant of Barley 1

    PubMed Central

    Walker-Simmons, Mary; Kudrna, David A.; Warner, Robert L.

    1989-01-01

    A barley (Hordeum vulgare L.) mutant (Az34) has been identified with low basal levels of abscisic acid (ABA) and with reduced capacity for producing ABA in response to water stress. The mutation is in a gene controlling the molybdenum cofactor resulting in a pleiotropic deficiency in at least three molybdoenzymes, nitrate reductase, xanthine dehydrogenase, and aldehyde oxidase. The mutant was found to lack aldehyde oxidase activity with several substrates including: (a) ABA aldehyde, a putative precursor of ABA; (b) an acetylenic analog of ABA aldehyde; and (c) heptaldehyde. Elevating the growth temperature from 18 to 26°C caused mutant leaves to wilt and brown. Desiccation of mutant leaves was prevented by applying ABA. These results indicate that ABA biosynthesis at some developmental stages is dependent upon a molybdoenzyme which may be an aldehyde oxidase. Images Figure 5 PMID:16666835

  1. Improved cold tolerance in Elymus nutans by exogenous application of melatonin may involve ABA-dependent and ABA-independent pathways

    PubMed Central

    Fu, Juanjuan; Wu, Ye; Miao, Yanjun; Xu, Yamei; Zhao, Enhua; Wang, Jin; Sun, Huaien; Liu, Qian; Xue, Yongwei; Xu, Yuefei; Hu, Tianming

    2017-01-01

    Melatonin is an important secondary messenger that plays a central role in plant growth, as well as abiotic and biotic stress tolerance. However, the underlying physiological and molecular mechanisms of melatonin-mediated cold tolerance, especially interactions between melatonin and other key molecules in the plant stress response, remain unknown. Here, the interrelation between melatonin and abscisic acid (ABA) was investigated in two genotypes of Elymus nutans Griseb., the cold-tolerant Damxung (DX) and the cold-sensitive Gannan (GN) under cold stress. Pre-treatment with exogenous melatonin or ABA alleviated oxidative injury via scavenging ROS, while enhancing both antioxidant enzyme activities and non-enzymatic antioxidant contents. Treatment of fluridone, an ABA biosynthesis inhibitor caused membrane lipid peroxidation and lowered melatonin-induced antioxidant defense responses. It is worth noting that cold stress significantly induced both endogenous melatonin and ABA levels in both genotypes. Application of melatonin increased ABA production, while fluridone significantly suppressed melatonin-induced ABA accumulation. ABA and fluridone pre-treatments failed to affect the endogenous melatonin concentration. Moreover, exogenous melatonin up-regulated the expression of cold-responsive genes in an ABA-independent manner. These results indicate that both ABA-dependent and ABA-independent pathways may contribute to melatonin-induced cold tolerance in E. nutans. PMID:28045095

  2. ABA inhibits entry into stomatal-lineage development in Arabidopsis leaves.

    PubMed

    Tanaka, Yoko; Nose, Tomoe; Jikumaru, Yusuke; Kamiya, Yuji

    2013-05-01

    The number and density of stomata are controlled by endogenous and environmental factors. Despite recent advances in our understanding of stomatal development, mechanisms which prevent stomatal-lineage entry remain unclear. Here, we propose that abscisic acid (ABA), a phytohormone known to induce stomatal closure, limits initiation of stomatal development and induces enlargement of pavement cells in Arabidopsis cotyledons. An ABA-deficient aba2-2 mutant had an increased number/proportion of stomata within a smaller cotyledon, as well as reduced expansion of pavement cells. This tendency was reversed after ABA application or in an ABA over-accumulating cyp707a1cyp707a3 doublemutant. Our time course analysis revealed that aba2-2 shows prolonged formation of meristemoids and guard mother cells, both precursors of stoma. This finding is in accordance with prolonged gene expression of SPCH and MUTE, master regulators for stomatal formation, indicating that ABA acts upstream of these genes. Only aba2-2 mute, but not aba2-2 spch double mutant showed additive phenotypes and displayed inhibition of pavement cell enlargement with increased meristemoid number, indicating that ABA action on pavement cell expansion requires the presence of stomatal-lineage cells.

  3. Chickpea transcription factor CaTLP1 interacts with protein kinases, modulates ROS accumulation and promotes ABA-mediated stomatal closure

    PubMed Central

    Wardhan, Vijay; Pandey, Aarti; Chakraborty, Subhra; Chakraborty, Niranjan

    2016-01-01

    Tubby and Tubby-like proteins (TLPs), in mammals, play critical roles in neural development, while its function in plants is largely unknown. We previously demonstrated that the chickpea TLP, CaTLP1, participates in osmotic stress response and might be associated with ABA-dependent network. However, how CaTLP1 is connected to ABA signaling remains unclear. The CaTLP1 was found to be engaged in ABA-mediated gene expression and stomatal closure. Complementation of the yeast yap1 mutant with CaTLP1 revealed its role in ROS scavenging. Furthermore, complementation of Arabidopsis attlp2 mutant displayed enhanced stress tolerance, indicating the functional conservation of TLPs across the species. The presence of ABA-responsive element along with other motifs in the proximal promoter regions of TLPs firmly established their involvement in stress signalling pathways. The CaTLP1 promoter driven GUS expression was restricted to the vegetative organs, especially stem and rosette leaves. Global protein expression profiling of wild-type, attlp2 and complemented Arabidopsis plants revealed 95 differentially expressed proteins, presumably involved in maintaining physiological and biological processes under dehydration. Immunoprecipitation assay revealed that protein kinases are most likely to interact with CaTLP1. This study provides the first demonstration that the TLPs act as module for ABA-mediated stomatal closure possibly via interaction with protein kinase. PMID:27934866

  4. Unravelling molecular responses to moderate dehydration in harvested fruit of sweet orange (Citrus sinensis L. Osbeck) using a fruit-specific ABA-deficient mutant

    PubMed Central

    Romero, Paco; Rodrigo, María J.; Alférez, Fernando; Ballester, Ana-Rosa; González-Candelas, Luis; Zacarías, Lorenzo; Lafuente, María T.

    2012-01-01

    Water stress affects many agronomic traits that may be regulated by the phytohormone abscisic acid (ABA). Within these traits, loss of fruit quality becomes important in many citrus cultivars that develop peel damage in response to dehydration. To study peel dehydration transcriptional responsiveness in harvested citrus fruit and the putative role of ABA in this process, this study performed a comparative large-scale transcriptional analysis of water-stressed fruits of the wild-type Navelate orange (Citrus sinesis L. Osbeck) and its spontaneous ABA-deficient mutant Pinalate, which is more prone to dehydration and to developing peel damage. Major changes in gene expression occurring in the wild-type line were impaired in the mutant fruit. Gene ontology analysis revealed the ability of Navelate fruits to induce the response to water deprivation and di-, tri-valent inorganic cation transport biological processes, as well as repression of the carbohydrate biosynthesis process in the mutant. Exogenous ABA triggered relevant transcriptional changes and repressed the protein ubiquitination process, although it could not fully rescue the physiological behaviour of the mutant. Overall, the results indicated that dehydration responsiveness requires ABA-dependent and -independent signals, and highlight that the ability of citrus fruits to trigger molecular responses against dehydration is an important factor in reducing their susceptibility to developing peel damage. PMID:22315241

  5. Unravelling molecular responses to moderate dehydration in harvested fruit of sweet orange (Citrus sinensis L. Osbeck) using a fruit-specific ABA-deficient mutant.

    PubMed

    Romero, Paco; Rodrigo, María J; Alférez, Fernando; Ballester, Ana-Rosa; González-Candelas, Luis; Zacarías, Lorenzo; Lafuente, María T

    2012-04-01

    Water stress affects many agronomic traits that may be regulated by the phytohormone abscisic acid (ABA). Within these traits, loss of fruit quality becomes important in many citrus cultivars that develop peel damage in response to dehydration. To study peel dehydration transcriptional responsiveness in harvested citrus fruit and the putative role of ABA in this process, this study performed a comparative large-scale transcriptional analysis of water-stressed fruits of the wild-type Navelate orange (Citrus sinesis L. Osbeck) and its spontaneous ABA-deficient mutant Pinalate, which is more prone to dehydration and to developing peel damage. Major changes in gene expression occurring in the wild-type line were impaired in the mutant fruit. Gene ontology analysis revealed the ability of Navelate fruits to induce the response to water deprivation and di-, tri-valent inorganic cation transport biological processes, as well as repression of the carbohydrate biosynthesis process in the mutant. Exogenous ABA triggered relevant transcriptional changes and repressed the protein ubiquitination process, although it could not fully rescue the physiological behaviour of the mutant. Overall, the results indicated that dehydration responsiveness requires ABA-dependent and -independent signals, and highlight that the ability of citrus fruits to trigger molecular responses against dehydration is an important factor in reducing their susceptibility to developing peel damage.

  6. The Arabidopsis Trehalose-6-P Synthase AtTPS1 Gene Is a Regulator of Glucose, Abscisic Acid, and Stress Signaling1

    PubMed Central

    Avonce, Nelson; Leyman, Barbara; Mascorro-Gallardo, José O.; Van Dijck, Patrick; Thevelein, Johan M.; Iturriaga, Gabriel

    2004-01-01

    In Arabidopsis (Arabidopsis thaliana), trehalose is present at almost undetectable levels, excluding its role as an osmoprotectant. Here, we report that overexpression of AtTPS1 in Arabidopsis using the 35S promoter led to a small increase in trehalose and trehalose-6-P levels. In spite of this, transgenic plants displayed a dehydration tolerance phenotype without any visible morphological alterations, except for delayed flowering. Moreover, seedlings overexpressing AtTPS1 exhibited glucose (Glc)- and abscisic acid (ABA)-insensitive phenotypes. Transgenic seedlings germinated on Glc were visibly larger with green well-expanded cotyledonary leaves and fully developed roots, in contrast with wild-type seedlings showing growth retardation and absence of photosynthetic tissue. An ABA dose-response experiment revealed a higher germination rate for transgenic plants overexpressing AtTPS1 showing insensitive germination kinetics at 2.5 μm ABA. Interestingly, germination in the presence of Glc did not trigger an increase in ABA content in plants overexpressing AtTPS1. Expression analysis by quantitative reverse transcription-PCR in transgenic plants showed up-regulation of the ABI4 and CAB1 genes. In the presence of Glc, CAB1 expression remained high, whereas ABI4, HXK1, and ApL3 levels were down-regulated in the AtTPS1-overexpressing lines. Analysis of AtTPS1 expression in HXK1-antisense or HXK1-sense transgenic lines suggests the possible involvement of AtTPS1 in the hexokinase-dependent Glc-signaling pathway. These data strongly suggest that AtTPS1 has a pivotal role in the regulation of Glc and ABA signaling during vegetative development. PMID:15516499

  7. Arabidopsis HY1-Modulated Stomatal Movement: An Integrative Hub Is Functionally Associated with ABI4 in Dehydration-Induced ABA Responsiveness1

    PubMed Central

    Xie, Yanjie; Mao, Yu; Duan, Xingliang; Zhou, Heng; Lai, Diwen; Zhang, Yihua; Shen, Wenbiao

    2016-01-01

    Heme oxygenase (HO; EC 1.14.99.3) has recently been proposed as a novel component in mediating wide ranges of the plant adaptive signaling processes. However, the physiological significance and molecular basis underlying Arabidopsis (Arabidopsis thaliana) HO1 (HY1) functioning in drought tolerance remained unclear. Here, we report that mutation of HY1 promoted, but overexpression of this gene impaired, Arabidopsis drought tolerance. This was attributed to the abscisic acid (ABA)-hypersensitive or -hyposensitive phenotypes, with the regulation of stomatal closure in particular. However, comparative transcriptomic profile analysis showed that the induction of numerous ABA/stress-dependent genes in dehydrated wild-type plants was differentially impaired in the hy1 mutant. In agreement, ABA-induced ABSCISIC ACID-INSENSITIVE4 (ABI4) transcript accumulation was strengthened in the hy1 mutant. Genetic analysis further identified that the hy1-associated ABA hypersensitivity and drought tolerance were arrested in the abi4 background. Moreover, the promotion of ABA-triggered up-regulation of RbohD abundance and reactive oxygen species (ROS) levels in the hy1 mutant was almost fully blocked by the mutation of ABI4, suggesting that the HY1-ABI4 signaling in the wild type involved in stomatal closure was dependent on the RbohD-derived ROS production. However, hy1-promoted stomatal closure was not affected by a nitric oxide scavenger. Correspondingly, ABA-insensitive behaviors in rbohD stomata were not affected by either the mutation of HY1 or its ectopic expression in the rbohD background, both of which responded significantly to exogenous ROS. These data indicate that HY1 functioned negatively and acted upstream of ABI4 in drought signaling, which was casually dependent on the RbohD-derived ROS in the regulation of stomatal closure. PMID:26704641

  8. A bHLH-Type Transcription Factor, ABA-INDUCIBLE BHLH-TYPE TRANSCRIPTION FACTOR/JA-ASSOCIATED MYC2-LIKE1, Acts as a Repressor to Negatively Regulate Jasmonate Signaling in Arabidopsis[C][W

    PubMed Central

    Nakata, Masaru; Mitsuda, Nobutaka; Herde, Marco; Koo, Abraham J.K.; Moreno, Javier E.; Suzuki, Kaoru; Howe, Gregg A.; Ohme-Takagi, Masaru

    2013-01-01

    Jasmonates (JAs) are plant hormones that regulate the balance between plant growth and responses to biotic and abiotic stresses. Although recent studies have uncovered the mechanisms for JA-induced responses in Arabidopsis thaliana, the mechanisms by which plants attenuate the JA-induced responses remain elusive. Here, we report that a basic helix-loop-helix–type transcription factor, ABA-INDUCIBLE BHLH-TYPE TRANSCRIPTION FACTOR/JA-ASSOCIATED MYC2-LIKE1 (JAM1), acts as a transcriptional repressor and negatively regulates JA signaling. Gain-of-function transgenic plants expressing the chimeric repressor for JAM1 exhibited substantial reduction of JA responses, including JA-induced inhibition of root growth, accumulation of anthocyanin, and male fertility. These plants were also compromised in resistance to attack by the insect herbivore Spodoptera exigua. Conversely, jam1 loss-of-function mutants showed enhanced JA responsiveness, including increased resistance to insect attack. JAM1 and MYC2 competitively bind to the target sequence of MYC2, which likely provides the mechanism for negative regulation of JA signaling and suppression of MYC2 functions by JAM1. These results indicate that JAM1 negatively regulates JA signaling, thereby playing a pivotal role in fine-tuning of JA-mediated stress responses and plant growth. PMID:23673982

  9. ABA-mediated transcriptional regulation in response to osmotic stress in plants.

    PubMed

    Fujita, Yasunari; Fujita, Miki; Shinozaki, Kazuo; Yamaguchi-Shinozaki, Kazuko

    2011-07-01

    The plant hormone abscisic acid (ABA) plays a pivotal role in a variety of developmental processes and adaptive stress responses to environmental stimuli in plants. Cellular dehydration during the seed maturation and vegetative growth stages induces an increase in endogenous ABA levels, which control many dehydration-responsive genes. In Arabidopsis plants, ABA regulates nearly 10% of the protein-coding genes, a much higher percentage than other plant hormones. Expression of the genes is mainly regulated by two different families of bZIP transcription factors (TFs), ABI5 in the seeds and AREB/ABFs in the vegetative stage, in an ABA-responsive-element (ABRE) dependent manner. The SnRK2-AREB/ABF pathway governs the majority of ABA-mediated ABRE-dependent gene expression in response to osmotic stress during the vegetative stage. In addition to osmotic stress, the circadian clock and light conditions also appear to participate in the regulation of ABA-mediated gene expression, likely conferring versatile tolerance and repressing growth under stress conditions. Moreover, various other TFs belonging to several classes, including AP2/ERF, MYB, NAC, and HD-ZF, have been reported to engage in ABA-mediated gene expression. This review mainly focuses on the transcriptional regulation of ABA-mediated gene expression in response to osmotic stress during the vegetative growth stage in Arabidopsis.

  10. Abscisic Acid-Induced Resistance against the Brown Spot Pathogen Cochliobolus miyabeanus in Rice Involves MAP Kinase-Mediated Repression of Ethylene Signaling1[C][W][OA

    PubMed Central

    De Vleesschauwer, David; Yang, Yinong; Vera Cruz, Casiana; Höfte, Monica

    2010-01-01

    The plant hormone abscisic acid (ABA) is involved in an array of plant processes, including the regulation of gene expression during adaptive responses to various environmental cues. Apart from its well-established role in abiotic stress adaptation, emerging evidence indicates that ABA is also prominently involved in the regulation and integration of pathogen defense responses. Here, we demonstrate that exogenously administered ABA enhances basal resistance of rice (Oryza sativa) against the brown spot-causing ascomycete Cochliobolus miyabeanus. Microscopic analysis of early infection events in control and ABA-treated plants revealed that this ABA-inducible resistance (ABA-IR) is based on restriction of fungal progression in the mesophyll. We also show that ABA-IR does not rely on boosted expression of salicylic acid-, jasmonic acid -, or callose-dependent resistance mechanisms but, instead, requires a functional Gα-protein. In addition, several lines of evidence are presented suggesting that ABA steers its positive effect on brown spot resistance through antagonistic cross talk with the ethylene (ET) response pathway. Exogenous ethephon application enhances susceptibility, whereas genetic disruption of ET signaling renders plants less vulnerable to C. miyabeanus attack, thereby inducing a level of resistance similar to that observed on ABA-treated wild-type plants. Moreover, ABA treatment alleviates C. miyabeanus-induced activation of the ET reporter gene EBP89, while derepression of pathogen-triggered EBP89 transcription via RNA interference-mediated knockdown of OsMPK5, an ABA-primed mitogen-activated protein kinase gene, compromises ABA-IR. Collectively, these data favor a model whereby exogenous ABA enhances resistance against C. miyabeanus at least in part by suppressing pathogen-induced ET action in an OsMPK5-dependent manner. PMID:20130100

  11. Auxin Response Factor2 (ARF2) and Its Regulated Homeodomain Gene HB33 Mediate Abscisic Acid Response in Arabidopsis

    PubMed Central

    Wang, Li; Hua, Deping; He, Junna; Duan, Ying; Chen, Zhizhong; Hong, Xuhui; Gong, Zhizhong

    2011-01-01

    The phytohormone abscisic acid (ABA) is an important regulator of plant development and response to environmental stresses. In this study, we identified two ABA overly sensitive mutant alleles in a gene encoding Auxin Response Factor2 (ARF2). The expression of ARF2 was induced by ABA treatment. The arf2 mutants showed enhanced ABA sensitivity in seed germination and primary root growth. In contrast, the primary root growth and seed germination of transgenic plants over-expressing ARF2 are less inhibited by ABA than that of the wild type. ARF2 negatively regulates the expression of a homeodomain gene HB33, the expression of which is reduced by ABA. Transgenic plants over-expressing HB33 are more sensitive, while transgenic plants reducing HB33 by RNAi are more resistant to ABA in the seed germination and primary root growth than the wild type. ABA treatment altered auxin distribution in the primary root tips and made the relative, but not absolute, auxin accumulation or auxin signal around quiescent centre cells and their surrounding columella stem cells to other cells stronger in arf2-101 than in the wild type. These results indicate that ARF2 and HB33 are novel regulators in the ABA signal pathway, which has crosstalk with auxin signal pathway in regulating plant growth. PMID:21779177

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

    PubMed Central

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

    2016-01-01

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

  13. Light signalling mediated by phytochrome plays an important role in cold-induced gene expression through the C-repeat/dehydration responsive element (C/DRE) in Arabidopsis thaliana.

    PubMed

    Kim, Hyoun-Joung; Kim, Yun-Kyoung; Park, Jin-Young; Kim, Jungmook

    2002-03-01

    Low temperature induces a number of genes that encode the proteins promoting tolerance to freezing, mediated by ABA-dependent and ABA-independent pathways in plants. The cis-acting element called C/DRE is known to respond to low temperature independently of ABA action. To investigate the signalling and network of ABA-independent pathways, the transgenic Arabidopsis plants were generated containing several copies of the C/DRE derived from cor15a gene with a minimal promoter fused to a GUS reporter gene. The transgenic plants containing four copies of the C/DRE (4C/DRE-GUS) showed responsiveness to cold and drought treatments and were used for characterization of cold signalling and cross-talk. Cold-induced GUS expression was inhibited by okadaic acid at 1 nM, indicating that protein phosphatase 2A might act as a positive regulator. Light was shown to activate cold- and drought-induced GUS expression. Photo-reversibility of the GUS mRNA by red and far-red light with concomitant cold treatment suggests a role of phytochrome as a photoreceptor in mediating light signalling to activate the cold-induced gene expression through the C/DRE. Furthermore, GUS expression analysis in phyA or phyB or phyAphyB mutant backgrounds showed that phytochrome B is a primary photoreceptor responsible for the activation of cold-stress signalling in response to light. Light enhanced the induction kinetics of CBF1, 2, and 3 encoding the cognate transcription factors, and cor15a, in a consecutive manner compared to the dark condition in the cold, suggesting that the connection point between cold and light signalling mediated by phytochrome is at a higher step than the expression of CBF genes.

  14. The WD40 Domain Protein MSI1 Functions in a Histone Deacetylase Complex to Fine-Tune Abscisic Acid Signaling

    PubMed Central

    Bergquist, Jonas

    2016-01-01

    MSI1 belongs to a family of histone binding WD40-repeat proteins. Arabidopsis thaliana contains five genes encoding MSI1-like proteins, but their functions in diverse chromatin-associated complexes are poorly understood. Here, we show that MSI1 is part of a histone deacetylase complex. We copurified HISTONE DEACETYLASE19 (HDA19) with MSI1 and transcriptional regulatory SIN3-like proteins and provide evidence that MSI1 and HDA19 associate into the same complex in vivo. These data suggest that MSI1, HDA19, and HISTONE DEACETYLATION COMPLEX1 protein form a core complex that can integrate various SIN3-like proteins. We found that reduction of MSI1 or HDA19 causes upregulation of abscisic acid (ABA) receptor genes and hypersensitivity of ABA-responsive genes. The MSI1-HDA19 complex fine-tunes ABA signaling by binding to the chromatin of ABA receptor genes and by maintaining low levels of acetylation of histone H3 at lysine 9, thereby affecting the expression levels of ABA receptor genes. Reduced MSI1 or HDA19 levels led to increased tolerance to salt stress corresponding to the increased ABA sensitivity of gene expression. Together, our results reveal the presence of an MSI1-HDA19 complex that fine-tunes ABA signaling in Arabidopsis. PMID:26704384

  15. The WD40 Domain Protein MSI1 Functions in a Histone Deacetylase Complex to Fine-Tune Abscisic Acid Signaling.

    PubMed

    Mehdi, Saher; Derkacheva, Maria; Ramström, Margareta; Kralemann, Lejon; Bergquist, Jonas; Hennig, Lars

    2016-01-01

    MSI1 belongs to a family of histone binding WD40-repeat proteins. Arabidopsis thaliana contains five genes encoding MSI1-like proteins, but their functions in diverse chromatin-associated complexes are poorly understood. Here, we show that MSI1 is part of a histone deacetylase complex. We copurified HISTONE DEACETYLASE19 (HDA19) with MSI1 and transcriptional regulatory SIN3-like proteins and provide evidence that MSI1 and HDA19 associate into the same complex in vivo. These data suggest that MSI1, HDA19, and HISTONE DEACETYLATION COMPLEX1 protein form a core complex that can integrate various SIN3-like proteins. We found that reduction of MSI1 or HDA19 causes upregulation of abscisic acid (ABA) receptor genes and hypersensitivity of ABA-responsive genes. The MSI1-HDA19 complex fine-tunes ABA signaling by binding to the chromatin of ABA receptor genes and by maintaining low levels of acetylation of histone H3 at lysine 9, thereby affecting the expression levels of ABA receptor genes. Reduced MSI1 or HDA19 levels led to increased tolerance to salt stress corresponding to the increased ABA sensitivity of gene expression. Together, our results reveal the presence of an MSI1-HDA19 complex that fine-tunes ABA signaling in Arabidopsis.

  16. The site of water stress governs the pattern of ABA synthesis and transport in peanut

    PubMed Central

    Hu, Bo; Cao, Jiajia; Ge, Kui; Li, Ling

    2016-01-01

    Abscisic acid (ABA) is one of the most important phytohormones involved in stress responses in plants. However, knowledge of the effect on ABA distribution and transport of water stress at different sites on the plant is limited. In this study, water stress imposed on peanut leaves or roots by treatment with PEG 6000 is termed “leaf stress” or “root stress”, respectively. Immunoenzyme localization technolony was first used to detect ABA distribution in peanut. Under root stress, ABA biosynthesis and distribution level were all more pronounced in root than in leaf. However, ABA transport and the ability to induce stomatal closure were still better in leaf than in root during root stress; However, ABA biosynthesis initially increased in leaf, then rapidly accumulated in the vascular cambium of leaves and induced stomatal closure under leaf stress; ABA produced in root tissues was also transported to leaf tissues to maintain stomatal closure. The vascular system was involved in the coordination and integration of this complex regulatory mechanism for ABA signal accumulation. Water stress subject to root or leaf results in different of ABA biosynthesis and transport ability that trigger stoma close in peanut. PMID:27694957

  17. Transcriptome analysis reveals specific modulation of abscisic acid signaling by ROP10 small GTPase in Arabidopsis.

    PubMed

    Xin, Zeyu; Zhao, Yihong; Zheng, Zhi-Liang

    2005-11-01

    Abscisic acid (ABA) is a hormone that modulates a variety of agronomically important growth and developmental processes and various stresses responses, but its signal transduction pathways remain poorly understood. ROP10, a member of ROP small GTPases in Arabidopsis (Arabidopsis thaliana), is a plasma membrane-associated protein specifically involved in negative regulation of ABA responses. To dissect the ROP10-mediated ABA signaling, we carried out transcriptome analysis using the Arabidopsis full-genome chip. Our analysis revealed a total of 262 and 125 genes that were, respectively, up- and down-regulated (> or =2-fold cutoff) by 1 mum ABA in wild type (Wassilewskija [Ws]); 42 up-regulated and 38 down-regulated genes have not been identified in other studies. Consistent with the nonpleiotropic phenotypes of rop10-1, only three genes were altered in rop10-1 in the absence of ABA treatment. In response to 1 microm ABA, 341 and 127 genes were, respectively, activated and repressed in rop10-1. Interestingly, a particular subset of 21 genes that were not altered by 1 microm ABA in Ws but only activated in rop10-1 was identified. Reverse transcription-polymerase chain reaction analysis revealed the existence of three distinct categories of ABA dose-response patterns. One novel category is characterized by their ABA unresponsiveness in Ws and activation in rop10-1 at 1 microm but not 10 and 100 microm of ABA. This indicates that ROP10 gates the expression of genes that are specific to low concentrations of ABA. Furthermore, almost all of these 21 genes are known to be highly induced by various biotic and abiotic stresses. Consequently, we found that rop10-1 enhanced the sensitivity of seed germination inhibition to mannitol and sodium chloride. Our results suggest that ROP10 negatively regulates ABA responses by specifically and differentially modulating the ABA sensitivity of a subset of genes including protein kinases and zinc-finger family proteins.

  18. Ethylene-dependent/ethylene-independent ABA regulation of tomato plants colonized by arbuscular mycorrhiza fungi.

    PubMed

    Martín-Rodríguez, José Ángel; León-Morcillo, Rafael; Vierheilig, Horst; Ocampo, Juan Antonio; Ludwig-Müller, Jutta; García-Garrido, José Manuel

    2011-04-01

    We investigated the relationship between ABA and ethylene regulating the formation of the arbuscular mycorrhiza (AM) symbiosis in tomato (Solanum lycopersicum) plants and tried to define the specific roles played by each of these phytohormones in the mycorrhization process. We analysed the impact of ABA biosynthesis inhibition on mycorrhization by Glomus intraradices in transgenic tomato plants with an altered ethylene pathway. We also studied the effects on mycorrhization in sitiens plants treated with the aminoethoxyvinyl glycine hydrochloride (AVG) ethylene biosynthesis inhibitor and supplemented with ABA. In addition, the expression of plant and fungal genes involved in the mycorrhization process was studied. ABA biosynthesis inhibition qualitatively altered the parameters of mycorrhization in accordance with the plant's ethylene perception and ethylene biosynthesis abilities. Inhibition of ABA biosynthesis in wild-type plants negatively affected all the mycorrhization parameters studied, while tomato mutants impaired in ethylene synthesis only showed a reduced arbuscular abundance in mycorrhizal roots. Inhibition of ethylene synthesis in ABA-deficient sitiens plants increased the intensity of mycorrhiza development, while ABA application rescued arbuscule abundance in the root's mycorrhizal zones. The results of our study show an antagonistic interaction between ABA and ethylene, and different roles of each of the two hormones during AM formation. This suggests that a dual ethylene-dependent/ethylene-independent mechanism is involved in ABA regulation of AM formation.

  19. Structural basis for selective activation of ABA receptors

    SciTech Connect

    Peterson, Francis C.; Burgie, E. Sethe; Park, Sang-Youl; Jensen, Davin R.; Weiner, Joshua J.; Bingman, Craig A.; Chang, Chia-En A.; Cutler, Sean R.; Phillips, Jr., George N.; Volkman, Brian F.

    2010-11-01

    Changing environmental conditions and lessening fresh water supplies have sparked intense interest in understanding and manipulating abscisic acid (ABA) signaling, which controls adaptive responses to drought and other abiotic stressors. We recently discovered a selective ABA agonist, pyrabactin, and used it to discover its primary target PYR1, the founding member of the PYR/PYL family of soluble ABA receptors. To understand pyrabactin's selectivity, we have taken a combined structural, chemical and genetic approach. We show that subtle differences between receptor binding pockets control ligand orientation between productive and nonproductive modes. Nonproductive binding occurs without gate closure and prevents receptor activation. Observations in solution show that these orientations are in rapid equilibrium that can be shifted by mutations to control maximal agonist activity. Our results provide a robust framework for the design of new agonists and reveal a new mechanism for agonist selectivity.

  20. Plant responses to drought stress and exogenous ABA application are modulated differently by mycorrhization in tomato and an ABA-deficient mutant (sitiens).

    PubMed

    Aroca, Ricardo; Del Mar Alguacil, Maria; Vernieri, Paolo; Ruiz-Lozano, Juan Manuel

    2008-11-01

    The aims of the present study are to find out whether the effects of arbuscular mycorrhizal (AM) symbiosis on plant resistance to water deficit are mediated by the endogenous abscisic acid (ABA) content of the host plant and whether the exogenous ABA application modifies such effects. The ABA-deficient tomato mutant sitiens and its near-isogenic wild-type parental line were used. Plant development, physiology, and expression of plant genes expected to be modulated by AM symbiosis, drought, and ABA were studied. Results showed that only wild-type tomato plants responded positively to mycorrhizal inoculation, while AM symbiosis was not observed to have any effect on plant development in sitiens plants grown under well-watered conditions. The application of ABA to sitiens plants enhanced plant growth both under well-watered and drought stress conditions. In respect to sitiens plants subjected to drought stress, the addition of ABA had a cumulative effect in relation to that of inoculation with G. intraradices. Most of the genes analyzed in this study showed different regulation patterns in wild-type and sitiens plants, suggesting that their gene expression is modulated by the plant ABA phenotype. In the same way, the colonization of roots with the AM fungus G. intraradices differently regulated the expression of these genes in wild-type and in sitiens plants, which could explain the distinctive effect of the symbiosis on each plant ABA phenotype. This also suggests that the effects of the AM symbiosis on plant responses and resistance to water deficit are mediated by the plant ABA phenotype.

  1. A Comprehensive Proteomic Survey of ABA-Induced Protein Phosphorylation in Rice (Oryza sativa L.)

    PubMed Central

    Qiu, Jiehua; Hou, Yuxuan; Wang, Yifeng; Li, Zhiyong; Zhao, Juan; Tong, Xiaohong; Lin, Haiyan; Wei, Xiangjin; Ao, Hejun; Zhang, Jian

    2017-01-01

    abscisic acid (ABA) is a key phytohormone regulating plant development and stress response. The signal transduction of ABA largely relies on protein phosphorylation. However; little is known about the phosphorylation events occurring during ABA signaling in rice thus far. By employing a label-free; MS (Mass Spectrometry)-based phosphoproteomic approach; we identified 2271 phosphosites of young rice seedlings and their intensity dynamics in response to ABA; during which 1060 proteins were found to be differentially phosphorylated. Western-blot analysis verified the differential phosphorylation pattern of D1, SMG1 and SAPK9 as indicated by the MS result; suggesting the high reliability of our phosphoproteomic data. The DP (differentially phosphorylated) proteins are extensively involved in ABA as well as other hormone signaling pathways. It is suggested that ABA antagonistically regulates brassinosteroid (BR) signaling via inhibiting BR receptor activity. The result of this study not only expanded our knowledge of rice phosphoproteome, but also shed more light on the pattern of protein phosphorylation in ABA signaling. PMID:28054942

  2. ABA in bryophytes: how a universal growth regulator in life became a plant hormone?

    PubMed

    Takezawa, Daisuke; Komatsu, Kenji; Sakata, Yoichi

    2011-07-01

    Abscisic acid (ABA) is not a plant-specific compound but one found in organisms across kingdoms from bacteria to animals, suggesting that it is a ubiquitous and versatile substance that can modulate physiological functions of various organisms. Recent studies have shown that plants developed an elegant system for ABA sensing and early signal transduction mechanisms to modulate responses to environmental stresses for survival in terrestrial conditions. ABA-induced increase in stress tolerance has been reported not only in vascular plants but also in non-vascular bryophytes. Since bryophytes are the key group of organisms in the context of plant evolution, clarification of their ABA-dependent processes is important for understanding evolutionary adaptation of land plants. Molecular approaches using Physcomitrella patens have revealed that ABA plays a role in dehydration stress tolerance in mosses, which comprise a major group of bryophytes. Furthermore, we recently reported that signaling machinery for ABA responses is also conserved in liverworts, representing the most basal members of extant land plant lineage. Conservation of the mechanism for ABA sensing and responses in angiosperms and basal land plants suggests that acquisition of this mechanism for stress tolerance in vegetative tissues was one of the critical evolutionary events for adaptation to the land. This review describes the role of ABA in basal land plants as well as non-land plant organisms and further elaborates on recent progress in molecular studies of model bryophytes by comparative and functional genomic approaches.

  3. A DTX/MATE-type transporter facilitates abscisic acid efflux and modulates ABA sensitivity and drought tolerance in Arabidopsis.

    PubMed

    Zhang, Haiwen; Zhu, Huifen; Pan, Yajun; Yu, Yuexuan; Luan, Sheng; Li, Legong

    2014-10-01

    Abscisic acid (ABA) regulates numerous physiological and developmental processes in plants. Recent studies identify intracellular ABA receptors, implicating the transport of ABA across cell membranes as crucial for ABA sensing and response. Here, we report that a DTX/Multidrug and Toxic Compound Extrusion (MATE) family member in Arabidopsis thaliana, AtDTX50, functions as an ABA efflux transporter. When expressed heterologously in both an Escherichia coli strain and Xenopus oocyte cells, AtDTX50 was found to facilitate ABA efflux. Furthermore, dtx50 mutant mesophyll cells preloaded with ABA released less ABA compared with the wild-type (WT). The AtDTX50 gene was expressed mainly in the vascular tissues and guard cells and its expression was strongly up-regulated by exogenous ABA. The AtDTX50::GFP fusion protein was localized predominantly to the plasma membrane. The dtx50 mutant plants were observed to be more sensitive to ABA in growth inhibition. In addition, compared with the WT, dtx50 mutant plants were more tolerant to drought with lower stomatal conductance, consistent with its function as an ABA efflux carrier in guard cells.

  4. Differential hormonal and gene expression dynamics in two inbred sunflower lines with contrasting dormancy level.

    PubMed

    Roselló, Paula L; Vigliocco, Ana E; Andrade, Andrea M; Riera, Natalí V; Calafat, Mario; Molas, María L; Alemano, Sergio G

    2016-05-01

    Seed germination and dormancy are tightly regulated by hormone metabolism and signaling pathway. We investigated the endogenous content of abscisic acid (ABA), its catabolites, and gibberellins (GAs), as well as the expression level of certain ABA and GAs metabolic and signaling genes in embryo of dry and imbibed cypselas of inbred sunflower (Helianthus annuus L., Asteraceae) lines: B123 (dormant) and B91 (non-dormant). Under our experimental conditions, the expression of RGL2 gene might be related to the ABA peak in B123 line at 3 h of imbibition. Indeed, RGL2 transcripts are absent in dry and early embedded cypselas of the non-dormant line B91. ABA increase was accompanied by a significant ABA-Glucosyl ester (ABA-GE) and phaseic acid (PA) (two ABA catabolites) decrease in B123 line (3 h) which indicates that ABA metabolism seems to be more active in this line, and that it would be involved in the imposition and maintenance of sunflower seed dormancy, as it has been reported for many species. Finally, an increase of bioactive GAs (GA1 and GA3) occurs at 12 h of imbibition in both lines after a decrease in ABA content. This study shows the first report about the RGL2 tissue-specific gene expression in sunflower inbred lines with contrasting dormancy level. Furthermore, our results provide evidence that ABA and GAs content and differential expression of metabolism and signaling genes would be interacting in seed dormancy regulation through a mechanism of action related to embryo itself.

  5. Expansion Mechanisms and Evolutionary History on Genes Encoding DNA Glycosylases and Their Involvement in Stress and Hormone Signaling

    PubMed Central

    Jiang, Shu-Ye; Ramachandran, Srinivasan

    2016-01-01

    DNA glycosylases catalyze the release of methylated bases. They play vital roles in the base excision repair pathway and might also function in DNA demethylation. At least three families of DNA glycosylases have been identified, which included 3′-methyladenine DNA glycosylase (MDG) I, MDG II, and HhH-GPD (Helix–hairpin–Helix and Glycine/Proline/aspartate (D)). However, little is known on their genome-wide identification, expansion, and evolutionary history as well as their expression profiling and biological functions. In this study, we have genome-widely identified and evolutionarily characterized these family members. Generally, a genome encodes only one MDG II gene in most of organisms. No MDG I or MDG II gene was detected in green algae. However, HhH-GPD genes were detectable in all available organisms. The ancestor species contain small size of MDG I and HhH-GPD families. These two families were mainly expanded through the whole-genome duplication and segmental duplication. They were evolutionarily conserved and were generally under purifying selection. However, we have detected recent positive selection among the Oryza genus, which might play roles in species divergence. Further investigation showed that expression divergence played important roles in gene survival after expansion. All of these family genes were expressed in most of developmental stages and tissues in rice plants. High ratios of family genes were downregulated by drought and fungus pathogen as well as abscisic acid (ABA) and jasmonic acid (JA) treatments, suggesting a negative regulation in response to drought stress and pathogen infection through ABA- and/or JA-dependent hormone signaling pathway. PMID:27026054

  6. Expansion Mechanisms and Evolutionary History on Genes Encoding DNA Glycosylases and Their Involvement in Stress and Hormone Signaling.

    PubMed

    Jiang, Shu-Ye; Ramachandran, Srinivasan

    2016-04-25

    DNA glycosylases catalyze the release of methylated bases. They play vital roles in the base excision repair pathway and might also function in DNA demethylation. At least three families of DNA glycosylases have been identified, which included 3'-methyladenine DNA glycosylase (MDG) I, MDG II, and HhH-GPD (Helix-hairpin-Helix and Glycine/Proline/aspartate (D)). However, little is known on their genome-wide identification, expansion, and evolutionary history as well as their expression profiling and biological functions. In this study, we have genome-widely identified and evolutionarily characterized these family members. Generally, a genome encodes only one MDG II gene in most of organisms. No MDG I or MDG II gene was detected in green algae. However, HhH-GPD genes were detectable in all available organisms. The ancestor species contain small size of MDG I and HhH-GPD families. These two families were mainly expanded through the whole-genome duplication and segmental duplication. They were evolutionarily conserved and were generally under purifying selection. However, we have detected recent positive selection among the Oryza genus, which might play roles in species divergence. Further investigation showed that expression divergence played important roles in gene survival after expansion. All of these family genes were expressed in most of developmental stages and tissues in rice plants. High ratios of family genes were downregulated by drought and fungus pathogen as well as abscisic acid (ABA) and jasmonic acid (JA) treatments, suggesting a negative regulation in response to drought stress and pathogen infection through ABA- and/or JA-dependent hormone signaling pathway.

  7. Abscisic Acid: a versatile phytohormone in plant signaling and beyond.

    PubMed

    Gomez-Cadenas, Aurelio; Vives, Vicente; Zandalinas, Sara I; Manzi, Matias; Sanchez-Perez, Ana M; Perez-Clemente, Rosa M; Arbona, Vicent

    2015-01-01

    As sessile organisms, plants cannot escape from adverse conditions and, therefore, they have developed complex responses to the changing environment. Plant responses to abiotic cues involve changes in metabolism, photosynthesis, gene expression, ion levels, etc., and must be perfectly coordinated by phytohormones. The abscisic acid (ABA) is the main phytohormone involved in abiotic stress responses although it is nowadays clear that its signaling pathways are not isolated but interconnected with other hormone signals in complex networks. This article revises molecular mechanisms involved in the crosstalks of ABA with other phytohormones in response to different physiological processes. Moreover, ABA is not a molecule exclusive from plants but it can be found in many other organisms including bacteria, algae, fungi, animals, etc. Interestingly, it can be synthesized and secreted by a variety of human cells. These aspects that confer to the ABA a range of ubiquitous molecule will be also revised in this article.

  8. Mechanistic Basis for Plant Responses to Drought Stress : Regulatory Mechanism of Abscisic Acid Signaling

    NASA Astrophysics Data System (ADS)

    Miyakawa, Takuya; Tanokura, Masaru

    The phytohormone abscisic acid (ABA) plays a key role in the rapid adaptation of plants to environmental stresses such as drought and high salinity. Accumulated ABA in plant cells promotes stomatal closure in guard cells and transcription of stress-tolerant genes. Our understanding of ABA responses dramatically improved by the discovery of both PYR/PYL/RCAR as a soluble ABA receptor and inhibitory complex of a protein phospatase PP2C and a protein kinase SnRK2. Moreover, several structural analyses of PYR/PYL/RCAR revealed the mechanistic basis for the regulatory mechanism of ABA signaling, which provides a rational framework for the design of alternative agonists in future.

  9. Glutathione peroxidase genes in Arabidopsis are ubiquitous and regulated by abiotic stresses through diverse signaling pathways.

    PubMed

    Rodriguez Milla, Miguel A; Maurer, Alberto; Rodriguez Huete, Alicia; Gustafson, J Perry

    2003-12-01

    Glutathione peroxidases (GPXs) are a group of enzymes that protect cells against oxidative damage generated by reactive oxygen species (ROS). The presence of GPXs in plants has been reported by several groups, but the roles of individual members of this family in a single plant species have not been studied. A family of seven related proteins named AtGPX1- AtGPX7 in Arabidopsis was identified, and the genomic organization of this family was reported. The putative subcellular localizations of the encoded proteins are the cytosol, chloroplast, mitochondria, and endoplasmic reticulum. Expressed sequence tags (ESTs) for all the genes except AtGPX7 were identified. Expression analysis of AtGPX genes in Arabidopsis tissues was performed, and different patterns were detected. Interestingly, several genes were up-regulated coordinately in response to abiotic stresses. AtGPX6, like human phospholipid hydroperoxide GPX (PHGPX), possibly encodes mitochondrial and cytosolic isoforms by alternative initiation. In addition, this gene showed the strongest responses under most abiotic stresses tested. AtGPX6::GUS analysis in transgenic Arabidopsis showed that AtGPX6 is highly expressed throughout development in most tissues, thus supporting an important role for this gene in protection against oxidative damage. The different effects of salicylic acid (SA), jasmonic acid (JA), abscisic acid (ABA), and auxin on the expression of the genes indicate that the AtGPX family is regulated by multiple signaling pathways. Analysis of the upstream region of the AtGPX genes revealed the presence of multiple conserved motifs, and some of them resembled antioxidant-responsive elements found in plant and human promoters. The potential regulatory role of specific sequences is discussed.

  10. Abscisic acid (ABA) receptors: light at the end of the tunnel

    PubMed Central

    McCormick, Sheila

    2010-01-01

    The plant hormone abscisic acid (ABA) plays a role in several aspects of plant growth and development. Understanding how this hormonal stimulus is sensed and transduced turned out to be one of the major tasks in the field of plant signaling. A series of recent papers proposed several different proteins that could receive the ABA signal and initiate the signaling cascade. The winner appears to be PYR/PYL/RCAR (PYrabactin Resistance/PYrabactin Resistance-Like/Regulatory Component of Abscisic acid Receptor) proteins, as crystal structures were recently published. The crystal structures support the idea that upon ABA binding to a PYR/PYL/RCAR protein, the activity of a phosphatase 2C, with known repressive activity on ABA signaling, is inhibited. PMID:20948817

  11. FYVE1/FREE1 Interacts with the PYL4 ABA Receptor and Mediates its Delivery to the Vacuolar Degradation Pathway.

    PubMed

    Belda-Palazon, Borja; Rodriguez, Lesia; Fernandez, Maria A; Castillo, Mari-Cruz; Anderson, Erin A; Gao, Caiji; González-Guzmán, Miguel; Peirats-Llobet, Marta; Zhao, Qiong; De Winne, Nancy; Gevaert, Kris; De Jaeger, Geert; Jiang, Liwen; Leon, Jose; Mullen, Robert T; Rodriguez, Pedro L

    2016-08-05

    Recently, we described the ubiquitylation of PYL4 and PYR1 by the RING E3 ubiquitin ligase RSL1 at the plasma membrane of Arabidopsis thaliana. This suggested that ubiquitylated ABA receptors might be targeted to the vacuolar degradation pathway because such ubiquitylation is usually an internalization signal for the endocytic route. Here, we show that FYVE1 (previously termed FREE1), a recently described component of the endosomal sorting complex required for transport (ESCRT) machinery, interacted with RSL1-receptor complexes and recruited PYL4 to endosomal compartments. Although the ESCRT pathway has been assumed to be reserved for integral membrane proteins, we show the involvement of this pathway in the degradation of ABA receptors, which can be associated with membranes but are not integral membrane proteins. Knock-down fyve1 alleles are hypersensitive to ABA, illustrating the biological relevance of the ESCRT pathway for the modulation of ABA signaling. In addition, fyve1 mutants are impaired in the targeting of ABA receptors for vacuolar degradation, leading to increased accumulation of PYL4 and an enhanced response to ABA. Pharmacological and genetic approaches revealed a dynamic turnover of ABA receptors from the plasma membrane to the endosomal/vacuolar degradation pathway, which was mediated by FYVE1 and was dependent on RSL1. This process involves clathrin-mediated endocytosis and trafficking of PYL4 through the ESCRT pathway, which helps to regulate the turnover of ABA receptors and attenuate ABA signaling.

  12. Nitrogen metabolism responses to water deficit act through both abscisic acid (ABA)-dependent and independent pathways in Medicago truncatula during post-germination.

    PubMed

    Planchet, Elisabeth; Rannou, Olivier; Ricoult, Claudie; Boutet-Mercey, Stéphanie; Maia-Grondard, Alessandra; Limami, Anis M

    2011-01-01

    The modulation of primary nitrogen metabolism by water deficit through ABA-dependent and ABA-independent pathways was investigated in the model legume Medicago truncatula. Growth and glutamate metabolism were followed in young seedlings growing for short periods in darkness and submitted to a moderate water deficit (simulated by polyethylene glycol; PEG) or treated with ABA. Water deficit induced an ABA accumulation, a reduction of axis length in an ABA-dependent manner, and an inhibition of water uptake/retention in an ABA-independent manner. The PEG-induced accumulation of free amino acids (AA), principally asparagine and proline, was mimicked by exogenous ABA treatment. This suggests that AA accumulation under water deficit may be an ABA-induced osmolyte accumulation contributing to osmotic adjustment. Alternatively, this accumulation could be just a consequence of a decreased nitrogen demand caused by reduced extension, which was triggered by water deficit and exogenous ABA treatment. Several enzyme activities involved in glutamate metabolism and genes encoding cytosolic glutamine synthetase (GS1b; EC 6.3.1.2.), glutamate dehydrogenase (GDH3; EC 1.4.1.1.), and asparagine synthetase (AS; EC 6.3.1.1.) were up-regulated by water deficit but not by ABA, except for a gene encoding Δ(1)-pyrroline-5-carboxylate synthetase (P5CS; EC not assigned). Thus, ABA-dependent and ABA-independent regulatory systems would seem to exist, differentially controlling development, water content, and nitrogen metabolism under water deficit.

  13. The PYL4 A194T Mutant Uncovers a Key Role of PYR1-LIKE4/PROTEIN PHOSPHATASE 2CA Interaction for Abscisic Acid Signaling and Plant Drought Resistance1[C][W][OPEN

    PubMed Central

    Pizzio, Gaston A.; Rodriguez, Lesia; Antoni, Regina; Gonzalez-Guzman, Miguel; Yunta, Cristina; Merilo, Ebe; Kollist, Hannes; Albert, Armando; Rodriguez, Pedro L.

    2013-01-01

    Because abscisic acid (ABA) is recognized as the critical hormonal regulator of plant stress physiology, elucidating its signaling pathway has raised promise for application in agriculture, for instance through genetic engineering of ABA receptors. PYRABACTIN RESISTANCE1/PYR1-LIKE (PYL)/REGULATORY COMPONENTS OF ABA RECEPTORS ABA receptors interact with high affinity and inhibit clade A phosphatases type-2C (PP2Cs) in an ABA-dependent manner. We generated an allele library composed of 10,000 mutant clones of Arabidopsis (Arabidopsis thaliana) PYL4 and selected mutations that promoted ABA-independent interaction with PP2CA/ABA-HYPERSENSITIVE3. In vitro protein-protein interaction assays and size exclusion chromatography confirmed that PYL4A194T was able to form stable complexes with PP2CA in the absence of ABA, in contrast to PYL4. This interaction did not lead to significant inhibition of PP2CA in the absence of ABA; however, it improved ABA-dependent inhibition of PP2CA. As a result, 35S:PYL4A194T plants showed enhanced sensitivity to ABA-mediated inhibition of germination and seedling establishment compared with 35S:PYL4 plants. Additionally, at basal endogenous ABA levels, whole-rosette gas exchange measurements revealed reduced stomatal conductance and enhanced water use efficiency compared with nontransformed or 35S:PYL4 plants and partial up-regulation of two ABA-responsive genes. Finally, 35S:PYL4A194T plants showed enhanced drought and dehydration resistance compared with nontransformed or 35S:PYL4 plants. Thus, we describe a novel approach to enhance plant drought resistance through allele library generation and engineering of a PYL4 mutation that enhances interaction with PP2CA. PMID:23864556

  14. High level transcription of a member of a repeated gene family confers dehydration tolerance to callus tissue of Craterostigma plantagineum.

    PubMed Central

    Furini, A; Koncz, C; Salamini, F; Bartels, D

    1997-01-01

    An experimental system has been developed which allows the identification of intermediates in the abscisic acid (ABA) signal transduction pathway leading to desiccation tolerance in plants. Desiccation tolerance in callus of the resurrection plant Craterostigma plantagineum is mediated via the plant hormone ABA, which induces the expression of gene products related to desiccation tolerance. Based on T-DNA activation tagging, a gene (CDT-1) was isolated which encodes a signalling molecule in the ABA transduction pathway. Constitutive overexpression of CDT-1 leads to desiccation tolerance in the absence of ABA and to the constitutive expression of characteristic transcripts. CDT-1 represents a novel gene with unusual features in its primary sequence.The CDT-1 gene resembles in several features SINE retrotransposons. Mechanisms by which CDT-1 activates the pathway could be via a regulatory RNA or via a short polypeptide. PMID:9218801

  15. Genotypic and Antimicrobial Susceptibility of Carbapenem-resistant Acinetobacter baumannii: Analysis of is Aba Elements and bla OXA-23-like Genes Including a New Variant.

    PubMed

    Bahador, Abbas; Raoofian, Reza; Pourakbari, Babak; Taheri, Mohammad; Hashemizadeh, Zahra; Hashemi, Farhad B

    2015-01-01

    Carbapenem-resistant Acinetobacter baumannii (CR-AB) causes serious nosocomial infections, especially in ICU wards of hospitals, worldwide. Expression of bla OXA genes is the chief mechanism of conferring carbapenem resistance among CR-AB. Although some bla OXA genes have been studied among CR-AB isolates from Iran, their bla OXA-23-like genes have not been investigated. We used a multiplex-PCR to detect Ambler class A, B, and D carbapenemases of 85 isolates, and determined that 34 harbored bla OXA-23-like genes. Amplified fragment length polymorphism (AFLP) genotyping, followed by DNA sequencing of bla OXA-23-like amplicons of CR-AB from each AFLP group was used to characterize their bla OXA-23-like genes. We also assessed the antimicrobial susceptibility pattern of CR-AB isolates, and tested whether they harbored insertion sequences ISAba1 and ISAba4. Sequence comparison with reference strain A. baumannii (NCTC12156) revealed five types of mutations in bla OXA-23-like genes; including one novel variant and four mutants that were already reported from China and the USA. All of the bla OXA-23-like genes mutations were associated with increased minimum inhibitory concentrations (MICs) against imipenem. ISAba1 and ISAba4 sequences were detected upstream of bla OXA-23 genes in 19 and 7% of isolates, respectively. The isolation of CR-AB with new bla OXA-23 mutations including some that have been reported from the USA and China highlights CR-AB pervasive distribution, which underscores the importance of concerted national and global efforts to control the spread of CR-AB isolates worldwide.

  16. Salt-Related MYB1 Coordinates Abscisic Acid Biosynthesis and Signaling during Salt Stress in Arabidopsis1

    PubMed Central

    Wang, Ting; Tohge, Takayuki; Ivakov, Alexander; Mueller-Roeber, Bernd; Fernie, Alisdair R.; Mutwil, Marek; Schippers, Jos H.M.; Persson, Staffan

    2015-01-01

    Abiotic stresses, such as salinity, cause global yield loss of all major crop plants. Factors and mechanisms that can aid in plant breeding for salt stress tolerance are therefore of great importance for food and feed production. Here, we identified a MYB-like transcription factor, Salt-Related MYB1 (SRM1), that negatively affects Arabidopsis (Arabidopsis thaliana) seed germination under saline conditions by regulating the levels of the stress hormone abscisic acid (ABA). Accordingly, several ABA biosynthesis and signaling genes act directly downstream of SRM1, including SALT TOLERANT1/NINE-CIS-EPOXYCAROTENOID DIOXYGENASE3, RESPONSIVE TO DESICCATION26, and Arabidopsis NAC DOMAIN CONTAINING PROTEIN19. Furthermore, SRM1 impacts vegetative growth and leaf shape. We show that SRM1 is an important transcriptional regulator that directly targets ABA biosynthesis and signaling-related genes and therefore may be regarded as an important regulator of ABA-mediated salt stress tolerance. PMID:26243618

  17. Melatonin promotes seed germination under high salinity by regulating antioxidant systems, ABA and GA₄ interaction in cucumber (Cucumis sativus L.).

    PubMed

    Zhang, Hai-Jun; Zhang, Na; Yang, Rong-Chao; Wang, Li; Sun, Qian-Qian; Li, Dian-Bo; Cao, Yun-Yun; Weeda, Sarah; Zhao, Bing; Ren, Shuxin; Guo, Yang-Dong

    2014-10-01

    Although previous studies have found that melatonin can promote seed germination, the mechanisms involved in perceiving and signaling melatonin remain poorly understood. In this study, it was found that melatonin was synthesized during cucumber seed germination with a peak in melatonin levels occurring 14 hr into germination. This is indicative of a correlation between melatonin synthesis and seed germination. Meanwhile, seeds pretreated with exogenous melatonin (1 μM) showed enhanced germination rates under 150 mM NaCl stress compared to water-pretreated seeds under salinity stress. There are two apparent mechanisms by which melatonin alleviated salinity-induced inhibition of seed germination. Exogenous melatonin decreased oxidative damage induced by NaCl stress by enhancing gene expression of antioxidants. Under NaCl stress, compared to untreated control, the activities of antioxidant enzymes including superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) were significantly increased by approximately 1.3-5.0-fold, with a concomitant 1.4-2.0-fold increase of CsCu-ZnSOD, CsFe-ZnSOD, CsCAT, and CsPOD in melatonin-pretreated seeds. Melatonin also alleviated salinity stress by affecting abscisic acid (ABA) and gibberellin acid (GA) biosynthesis and catabolism during seed germination. Compared to NaCl treatment, melatonin significantly up-regulated ABA catabolism genes (e.g., CsCYP707A1 and CsCYP707A2, 3.5 and 105-fold higher than NaCl treatment at 16 hr, respectively) and down-regulated ABA biosynthesis genes (e.g., CsNECD2, 0.29-fold of CK2 at 16 hr), resulting in a rapid decrease of ABA content during the early stage of germination. At the same time, melatonin positively up-regulated GA biosynthesis genes (e.g., GA20ox and GA3ox, 2.3 and 3.9-fold higher than NaCl treatment at 0 and 12 hr, respectively), contributing to a significant increase of GA (especially GA4) content. In this study, we provide new evidence suggesting that melatonin alleviates the

  18. Transcription Profiles Reveal Sugar and Hormone Signaling Pathways Mediating Flower Induction in Apple (Malus domestica Borkh.).

    PubMed

    Xing, Li-Bo; Zhang, Dong; Li, You-Mei; Shen, Ya-Wen; Zhao, Cai-Ping; Ma, Juan-Juan; An, Na; Han, Ming-Yu

    2015-10-01

    Flower induction in apple (Malus domestica Borkh.) is regulated by complex gene networks that involve multiple signal pathways to ensure flower bud formation in the next year, but the molecular determinants of apple flower induction are still unknown. In this research, transcriptomic profiles from differentiating buds allowed us to identify genes potentially involved in signaling pathways that mediate the regulatory mechanisms of flower induction. A hypothetical model for this regulatory mechanism was obtained by analysis of the available transcriptomic data, suggesting that sugar-, hormone- and flowering-related genes, as well as those involved in cell-cycle induction, participated in the apple flower induction process. Sugar levels and metabolism-related gene expression profiles revealed that sucrose is the initiation signal in flower induction. Complex hormone regulatory networks involved in cytokinin (CK), abscisic acid (ABA) and gibberellic acid pathways also induce apple flower formation. CK plays a key role in the regulation of cell formation and differentiation, and in affecting flowering-related gene expression levels during these processes. Meanwhile, ABA levels and ABA-related gene expression levels gradually increased, as did those of sugar metabolism-related genes, in developing buds, indicating that ABA signals regulate apple flower induction by participating in the sugar-mediated flowering pathway. Furthermore, changes in sugar and starch deposition levels in buds can be affected by ABA content and the expression of the genes involved in the ABA signaling pathway. Thus, multiple pathways, which are mainly mediated by crosstalk between sugar and hormone signals, regulate the molecular network involved in bud growth and flower induction in apple trees.

  19. Negative Regulation of Abscisic Acid Signaling by the Fagus sylvatica FsPP2C1 Plays A Role in Seed Dormancy Regulation and Promotion of Seed Germination1

    PubMed Central

    González-García, Mary Paz; Rodríguez, Dolores; Nicolás, Carlos; Rodríguez, Pedro Luis; Nicolás, Gregorio; Lorenzo, Oscar

    2003-01-01

    FsPP2C1 was previously isolated from beech (Fagus sylvatica) seeds as a functional protein phosphatase type-2C (PP2C) with all the conserved features of these enzymes and high homology to ABI1, ABI2, and PP2CA, PP2Cs identified as negative regulators of ABA signaling. The expression of FsPP2C1 was induced upon abscisic acid (ABA) treatment and was also up-regulated during early weeks of stratification. Furthermore, this gene was specifically expressed in ABA-treated seeds and was hardly detectable in vegetative tissues. In this report, to provide genetic evidence on FsPP2C1 function in seed dormancy and germination, we used an overexpression approach in Arabidopsis because transgenic work is not feasible in beech. Constitutive expression of FsPP2C1 under the cauliflower mosaic virus 35S promoter confers ABA insensitivity in Arabidopsis seeds and, consequently, a reduced degree of seed dormancy. Additionally, transgenic 35S:FsPP2C1 plants are able to germinate under unfavorable conditions, as inhibitory concentrations of mannitol, NaCl, or paclobutrazol. In vegetative tissues, Arabidopsis FsPP2C1 transgenic plants show ABA-resistant early root growth and diminished induction of the ABA-response genes RAB18 and KIN2, but no effect on stomatal closure regulation. Seed and vegetative phenotypes of Arabidopsis 35S:FsPP2C1 plants suggest that FsPP2C1 negatively regulates ABA signaling. The ABA inducibility of FsPP2C1 expression, together with the transcript accumulation mainly in seeds, suggest that it could play an important role modulating ABA signaling in beechnuts through a negative feedback loop. Finally, we suggest that negative regulation of ABA signaling by FsPP2C1 is a factor contributing to promote the transition from seed dormancy to germination during early weeks of stratification. PMID:12970481

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

    PubMed Central

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

    2013-01-01

    Plants are in danger of embolism formation in xylem vessels when the balance between water transport capacity and transpirational demand is compromised. To maintain this delicate balance, plants must regulate the rate of transpiration and, if necessary, restore water transport in embolized vessels. Abscisic acid (ABA) is the dominant long-distance signal responsible for plant response to stress, and it is possible that it plays a role in the embolism/refilling cycle. To test this idea, a temporal analysis of embolism and refilling dynamics, transpiration rate and starch content was performed on ABA-deficient mutant tomato plants. ABA-deficient mutants were more vulnerable to embolism formation than wild-type plants, and application of exogenous ABA had no effect on vulnerability. However, mutant plants treated with exogenous ABA had lower stomatal conductance and reduced starch content in the xylem parenchyma cells. The lower starch content could have an indirect effect on the plant’s refilling activity. The results confirm that plants with high starch content (moderately stressed mutant plants) were more likely to recover from loss of water transport capacity than plants with low starch content (mutant plants with application of exogenous ABA) or plants experiencing severe water stress. This study demonstrates that ABA most likely does not play any direct role in embolism refilling, but through the modulation of carbohydrate content, it could influence the plant’s capacity for refilling. PMID:23263667

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

    PubMed

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

    2012-12-24

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

  2. Mycorrhizal and non-mycorrhizal Lactuca sativa plants exhibit contrasting responses to exogenous ABA during drought stress and recovery

    PubMed Central

    Aroca, Ricardo; Vernieri, Paolo; Ruiz-Lozano, Juan Manuel

    2008-01-01

    The arbuscular mycorrhizal (AM) symbiosis enhances plant tolerance to water deficit through the alteration of plant physiology and the expression of plant genes. These changes have been postulated to be caused (among others) by different contents of abscisic acid (ABA) between AM and non-AM plants. However, there are no studies dealing with the effects of exogenous ABA on the expression of stress-related genes and on the physiology of AM plants. The aim of the present study was to evaluate the influence of AM symbiosis and exogenous ABA application on plant development, physiology, and expression of several stress-related genes after both drought and a recovery period. Results show that the application of exogenous ABA had contrasting effects on AM and non-AM plants. Only AM plants fed with exogenous ABA maintained shoot biomass production unaltered by drought stress. The addition of exogenous ABA enhanced considerably the ABA content in shoots of non-AM plants, concomitantly with the expression of the stress marker genes Lsp5cs and Lslea and the gene Lsnced. By contrast, the addition of exogenous ABA decreased the content of ABA in shoots of AM plants and did not produce any further enhancement of the expression of these three genes. AM plants always exhibited higher values of root hydraulic conductivity and reduced transpiration rate under drought stress. From plants subjected to drought, only the AM plants recovered their root hydraulic conductivity completely after the 3 d recovery period. As a whole, the results indicate that AM plants regulate their ABA levels better and faster than non-AM plants, allowing a more adequate balance between leaf transpiration and root water movement during drought and recovery. PMID:18469324

  3. ABA- and ethylene-mediated responses in osmotically stressed tomato are regulated by the TSS2 and TOS1 loci.

    PubMed

    Rosado, Abel; Amaya, Iraida; Valpuesta, Victoriano; Cuartero, Jesús; Botella, Miguel A; Borsani, Omar

    2006-01-01

    The study of mutants impaired in the sensitivity or synthesis of abscisic acid (ABA) has become a powerful tool to analyse the interactions occurring between the ABA and ethylene signalling pathways, with potential to change the traditional view of the role of ABA as just being involved in growth inhibition. The tss2 tomato mutant, which is hypersensitive to NaCl and osmotic stress, shows enhanced growth inhibition in the presence of exogenous ABA. The tos1 tomato mutant is also hypersensitive to osmotic stress, but in contrast to tss2, shows decreased sensitivity to ABA. Surprisingly, blocking ethylene signalling suppresses the growth defect of tss2 seedlings on ABA, NaCl, and osmotic stress, but not the osmotic hypersensitivity of tos1. The ethylene production of tss2 seedlings is increased compared with that of control seedlings under osmotic stress. In addition, the tss2 plants are hypersensitive to root growth inhibition by the ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC). This suggests that, in addition to ABA regulation, TSS2 acts as a negative regulator of endogenous ethylene accumulation. As previously shown in Arabidopsis, it is shown here that extensive cross-talk occurs between the ABA and ethylene signalling pathways in tomato and that the TSS2 and TOS1 loci appear as regulators of this cross-talk.

  4. Identification and mechanism of ABA receptor antagonism

    SciTech Connect

    Melcher, Karsten; Xu, Yong; Ng, Ley-Moy; Zhou, X. Edward; Soon, Fen-Fen; Chinnusamy, Viswanathan; Suino-Powell, Kelly M; Kovach, Amanda; Tham, Fook S.; Cutler, Sean R.; Li, Jun; Yong, Eu-Leong; Zhu, Jian-Kang; Xu, H. Eric

    2010-11-11

    The phytohormone abscisic acid (ABA) functions through a family of fourteen PYR/PYL receptors, which were identified by resistance to pyrabactin, a synthetic inhibitor of seed germination. ABA activates these receptors to inhibit type 2C protein phosphatases, such as ABI1, yet it remains unclear whether these receptors can be antagonized. Here we demonstrate that pyrabactin is an agonist of PYR1 and PYL1 but is unexpectedly an antagonist of PYL2. Crystal structures of the PYL2-pyrabactin and PYL1-pyrabactin-ABI1 complexes reveal the mechanism responsible for receptor-selective activation and inhibition, which enables us to design mutations that convert PYL1 to a pyrabactin-inhibited receptor and PYL2 to a pyrabactin-activated receptor and to identify new pyrabactin-based ABA receptor agonists. Together, our results establish a new concept of ABA receptor antagonism, illustrate its underlying mechanisms and provide a rational framework for discovering novel ABA receptor ligands.

  5. Gene Expressions for Signal Transduction under Acidic Conditions

    PubMed Central

    Fukamachi, Toshihiko; Ikeda, Syunsuke; Wang, Xin; Saito, Hiromi; Tagawa, Masatoshi; Kobayashi, Hiroshi

    2013-01-01

    Although it is now well known that some diseased areas, such as cancer nests, inflammation loci, and infarction areas, are acidified, little is known about cellular signal transduction, gene expression, and cellular functions under acidic conditions. Our group showed that different signal proteins were activated under acidic conditions compared with those observed in a typical medium of around pH 7.4 that has been used until now. Investigations of gene expression under acidic conditions may be crucial to our understanding of signal transduction in acidic diseased areas. In this study, we investigated gene expression in mesothelioma cells cultured at an acidic pH using a DNA microarray technique. After 24 h culture at pH 6.7, expressions of 379 genes were increased more than twofold compared with those in cells cultured at pH 7.5. Genes encoding receptors, signal proteins including transcription factors, and cytokines including growth factors numbered 35, 32, and 17 among the 379 genes, respectively. Since the functions of 78 genes are unknown, it can be argued that cells may have other genes for signaling under acidic conditions. The expressions of 37 of the 379 genes were observed to increase after as little as 2 h. After 24 h culture at pH 6.7, expressions of 412 genes were repressed more than twofold compared with those in cells cultured at pH 7.5, and the 412 genes contained 35, 76, and 7 genes encoding receptors, signal proteins including transcription factors, and cytokines including growth factors, respectively. These results suggest that the signal pathways in acidic diseased areas are different, at least in part, from those examined with cells cultured at a pH of around 7.4. PMID:24705103

  6. GsCBRLK, a calcium/calmodulin-binding receptor-like kinase, is a positive regulator of plant tolerance to salt and ABA stress.

    PubMed

    Yang, Liang; Ji, Wei; Zhu, Yanming; Gao, Peng; Li, Yong; Cai, Hua; Bai, Xi; Guo, Dianjing

    2010-05-01

    Calcium/calmodulin-dependent kinases play vital roles in protein phosphorylation in eukaryotes, yet little is known about the phosphorylation process of calcium/calmodulin-dependent protein kinase and its role in stress signal transduction in plants. A novel plant-specific calcium-dependent calmodulin-binding receptor-like kinase (GsCBRLK) has been isolated from Glycine soja. A subcellular localization study using GFP fusion protein indicated that GsCBRLK is localized in the plasma membrane. Binding assays demonstrated that calmodulin binds to GsCBRLK with an affinity of 25.9 nM in a calcium-dependent manner and the binding motif lies between amino acids 147 to169 within subdomain II of the kinase domain. GsCBRLK undergoes autophosphorylation and Myelin Basis Protein phosphorylation in the presence of calcium. It was also found that calcium/calmodulin positively regulates GsCBRLK kinase activity through direct interaction between the calmodulin-binding domain and calmodulin. So, it is likely that GsCBRLK responds to an environmental stimulus in two ways: by increasing the protein expression level and by regulating its kinase activity through the calcium/calmodulin complex. Furthermore, cold, salinity, drought, and ABA stress induce GsCBRLK gene transcripts. Over-expression of GsCBRLK in transgenic Arabidopsis resulted in enhanced plant tolerance to high salinity and ABA and increased the expression pattern of a number of stress gene markers in response to ABA and high salt. These results identify GsCBRLK as a molecular link between the stress- and ABA-induced calcium/calmodulin signal and gene expression in plant cells.

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

    PubMed

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

    2014-03-01

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

  8. The Magnesium-Chelatase H Subunit Binds Abscisic Acid and Functions in Abscisic Acid Signaling: New Evidence in Arabidopsis1[W][OA

    PubMed Central

    Wu, Fu-Qing; Xin, Qi; Cao, Zheng; Liu, Zhi-Qiang; Du, Shu-Yuan; Mei, Chao; Zhao, Chen-Xi; Wang, Xiao-Fang; Shang, Yi; Jiang, Tao; Zhang, Xiao-Feng; Yan, Lu; Zhao, Rui; Cui, Zi-Ning; Liu, Rui; Sun, Hai-Li; Yang, Xin-Ling; Su, Zhen; Zhang, Da-Peng

    2009-01-01

    Using a newly developed abscisic acid (ABA)-affinity chromatography technique, we showed that the magnesium-chelatase H subunit ABAR/CHLH (for putative abscisic acid receptor/chelatase H subunit) specifically binds ABA through the C-terminal half but not the N-terminal half. A set of potential agonists/antagonists to ABA, including 2-trans,4-trans-ABA, gibberellin, cytokinin-like regulator 6-benzylaminopurine, auxin indole-3-acetic acid, auxin-like substance naphthalene acetic acid, and jasmonic acid methyl ester, did not bind ABAR/CHLH. A C-terminal C370 truncated ABAR with 369 amino acid residues (631–999) was shown to bind ABA, which may be a core of the ABA-binding domain in the C-terminal half. Consistently, expression of the ABAR/CHLH C-terminal half truncated proteins fused with green fluorescent protein (GFP) in wild-type plants conferred ABA hypersensitivity in all major ABA responses, including seed germination, postgermination growth, and stomatal movement, and the expression of the same truncated proteins fused with GFP in an ABA-insensitive cch mutant of the ABAR/CHLH gene restored the ABA sensitivity of the mutant in all of the ABA responses. However, the effect of expression of the ABAR N-terminal half fused with GFP in the wild-type plants was limited to seedling growth, and the restoring effect of the ABA sensitivity of the cch mutant was limited to seed germination. In addition, we identified two new mutant alleles of ABAR/CHLH from the mutant pool in the Arabidopsis Biological Resource Center via Arabidopsis (Arabidopsis thaliana) Targeting-Induced Local Lesions in Genomes. The abar-2 mutant has a point mutation resulting in the N-terminal Leu-348→Phe, and the abar-3 mutant has a point mutation resulting in the N-terminal Ser-183→Phe. The two mutants show altered ABA-related phenotypes in seed germination and postgermination growth but not in stomatal movement. These findings support the idea that ABAR/CHLH is an ABA receptor and reveal

  9. Ascorbate Alleviates Fe Deficiency-Induced Stress in Cotton (Gossypium hirsutum) by Modulating ABA Levels.

    PubMed

    Guo, Kai; Tu, Lili; Wang, Pengcheng; Du, Xueqiong; Ye, Shue; Luo, Ming; Zhang, Xianlong

    2016-01-01

    Fe deficiency causes significant losses to crop productivity and quality. To understand better the mechanisms of plant responses to Fe deficiency, we used an in vitro cotton ovule culture system. We found that Fe deficiency suppressed the development of ovules and fibers, and led to tissue browning. RNA-seq analysis showed that the myo-inositol and galacturonic acid pathways were activated and cytosolic APX (ascorbate peroxidase) was suppressed in Fe-deficient treated fibers, which increased ASC (ascorbate) concentrations to prevent tissue browning. Suppression of cytosolic APX by RNAi in cotton increased ASC contents and delayed tissue browning by maintaining ferric reduction activity under Fe-deficient conditions. Meanwhile, APX RNAi line also exhibited the activation of expression of iron-regulated transporter (IRT1) and ferric reductase-oxidase2 (FRO2) to adapt to Fe deficiency. Abscisic acid (ABA) levels were significantly decreased in Fe-deficient treated ovules and fibers, while the upregulated expression of ABA biosynthesis genes and suppression of ABA degradation genes in Fe-deficient ovules slowed down the decreased of ABA in cytosolic APX suppressed lines to delay the tissue browning. Moreover, the application of ABA in Fe-deficient medium suppressed the development of tissue browning and completely restored the ferric reduction activity. In addition, ABA 8'-hydroxylase gene (GhABAH1) overexpressed cotton has a decreased level of ABA and shows more sensitivity to Fe deficiency. Based on the results, we speculate that ASC could improve the tolerance to Fe deficiency through activating Fe uptake and maintaining ABA levels in cotton ovules and fibers, which in turn reduces symptom formation.

  10. Ascorbate Alleviates Fe Deficiency-Induced Stress in Cotton (Gossypium hirsutum) by Modulating ABA Levels

    PubMed Central

    Guo, Kai; Tu, Lili; Wang, Pengcheng; Du, Xueqiong; Ye, Shue; Luo, Ming; Zhang, Xianlong

    2017-01-01

    Fe deficiency causes significant losses to crop productivity and quality. To understand better the mechanisms of plant responses to Fe deficiency, we used an in vitro cotton ovule culture system. We found that Fe deficiency suppressed the development of ovules and fibers, and led to tissue browning. RNA-seq analysis showed that the myo-inositol and galacturonic acid pathways were activated and cytosolic APX (ascorbate peroxidase) was suppressed in Fe-deficient treated fibers, which increased ASC (ascorbate) concentrations to prevent tissue browning. Suppression of cytosolic APX by RNAi in cotton increased ASC contents and delayed tissue browning by maintaining ferric reduction activity under Fe-deficient conditions. Meanwhile, APX RNAi line also exhibited the activation of expression of iron-regulated transporter (IRT1) and ferric reductase–oxidase2 (FRO2) to adapt to Fe deficiency. Abscisic acid (ABA) levels were significantly decreased in Fe-deficient treated ovules and fibers, while the upregulated expression of ABA biosynthesis genes and suppression of ABA degradation genes in Fe-deficient ovules slowed down the decreased of ABA in cytosolic APX suppressed lines to delay the tissue browning. Moreover, the application of ABA in Fe-deficient medium suppressed the development of tissue browning and completely restored the ferric reduction activity. In addition, ABA 8′-hydroxylase gene (GhABAH1) overexpressed cotton has a decreased level of ABA and shows more sensitivity to Fe deficiency. Based on the results, we speculate that ASC could improve the tolerance to Fe deficiency through activating Fe uptake and maintaining ABA levels in cotton ovules and fibers, which in turn reduces symptom formation. PMID:28101095

  11. Aureobasidium pullulans xylanase, gene and signal sequence

    DOEpatents

    Xin-Liang, Li; Ljungdahl, Lars G.

    1997-01-01

    A xylanase from Aureobasidium pullulans having a high specific activity is provided as well as a signal protein for controlling excretion into cell culture medium of proteins to which it is attached. DNA encoding these proteins is also provided.

  12. A Glycine soja ABA-responsive receptor-like cytoplasmic kinase, GsRLCK, positively controls plant tolerance to salt and drought stresses.

    PubMed

    Sun, XiaoLi; Sun, Mingzhe; Luo, Xiao; Ding, XiaoDong; Ji, Wei; Cai, Hua; Bai, Xi; Liu, XiaoFei; Zhu, YanMing

    2013-06-01

    Receptor such as protein kinases are proposed to work as sensors to initiate signaling cascades in higher plants. However, little is known about the precise functions of receptor such as protein kinases in abiotic stress response in plants, especially in wild soybean. Here, we focused on characterization of the biological functions of a receptor-like cytoplasmic serine/threonine protein kinase gene, GsRLCK, which was previously identified as a putative salt-alkali stress-related gene from the transcriptome profiles of Glycine soja. Bioinformatic analysis showed that GsRLCK protein contained a conserved kinase catalytic domain and two transmembrane domains at the N-terminus, but no typical extracellular domain. Consistently, GsRLCK-eGFP fusion protein was observed on the plasma membrane, but eGFP alone was distributing throughout the cytoplasm in onion epidermal cells. Quantitative real-time PCR analysis revealed the induced expression of GsRLCK by ABA, salt, alkali, and drought stresses. However, the expression levels of GsRLCK seemed to be similar in different tissues, except soybean pod. Phenotypic assays demonstrated that GsRLCK overexpression decreased ABA sensitivity and altered expression levels of ABA-responsive genes. Furthermore, we also found that GsRLCK conferred increased tolerance to salt and drought stresses and increased expression levels of a handful of stress-responsive genes, when overexpressing in Arabidopsis. In a word, we gave exact evidence that GsRLCK was a novel receptor-like cytoplasmic protein kinase and played a crucial role in plant responses to ABA, salt, and drought stresses.

  13. Differences in respiration between dormant and non-dormant buds suggest the involvement of ABA in the development of endodormancy in grapevines.

    PubMed

    Parada, Francisca; Noriega, Ximena; Dantas, Débora; Bressan-Smith, Ricardo; Pérez, Francisco J

    2016-08-20

    Grapevine buds (Vitis vinifera L) enter endodormancy (ED) after perceiving the short-day (SD) photoperiod signal and undergo metabolic changes that allow them to survive the winter temperatures. In the present study, we observed an inverse relationship between the depth of ED and the respiration rate of grapevine buds. Moreover, the respiration of dormant and non-dormant buds differed in response to temperature and glucose, two stimuli that normally increase respiration in plant tissues. While respiration in non-dormant buds rose sharply in response to both stimuli, respiration in dormant buds was only slightly affected. This suggests that a metabolic inhibitor is present. Here, we propose that the plant hormone abscisic acid (ABA) could be this inhibitor. ABA inhibits respiration in non-dormant buds and represses the expression of respiratory genes, such as ALTERNATIVE NADH DEHYDROGENASE (VaND1, VvaND2), CYTOCHROME OXIDASE (VvCOX6) and CYTOCHROME C (VvCYTC), and induces the expression of VvSnRK1, a gene encoding a member of a highly conserved family of protein kinases that act as energy sensors and regulate gene expression in response to energy depletion. In addition to inducing ED the SD-photoperiod up-regulated the expression of VvNCED, a gene that encodes a key enzyme in ABA synthesis. Taken together, these results suggest that ABA through the mediation of VvSnRK1, could play a key role in the regulation of the metabolic changes accompanying the entry into ED of grapevine buds.

  14. Are diurnal patterns of stomatal movement the result of alternating metabolism of endogenous guard cell ABA and accumulation of ABA delivered to the apoplast around guard cells by transpiration?

    PubMed

    Tallman, Gary

    2004-09-01

    Abscisic acid (ABA) prevents opening of closed stomata and causes open stomata to close. A dual-source model is proposed linking ABA to diurnal stomatal movements. Darkness would favour guard cell biosynthesis of endogenous ABA and disfavour ABA catabolism. At first light, xanthophyll cycling, isomerization of ABA precursors, and activation of a cytochrome P450 mono-oxygenase (CytP450) would deplete endogenous guard cell ABA. The NADPH-requiring CytP450 would be activated by elevated O2 and reduced CO2 concentrations resulting from mesophyll photosynthesis. An increased O2-to-CO2 ratio would limit the Calvin cycle in guard cells, diverting NADPH produced by photosynthetic electron transport to the cytosol where, along with elevated O2, it would activate CytP450. Depletion of endogenous ABA would liberate guard cells to extrude protons and accumulate the ions and water needed to increase guard cell turgor and open stomata. By midday, stomata would be regulated by steady-state concentrations of ABA delivered to the apoplast around guard cells by transpiration. In temperate conditions, ABA would reach concentrations high enough to trigger ion efflux from guard cells, but too low to defeat the accumulation of sugars used to maintain opening. In dry conditions, ABA would reach effective concentrations by midday, high enough to trigger ion efflux and inhibit sugar uptake, reducing apertures for the rest of the day. At sunset, conditions would again favour biosynthesis and disfavour catabolism of endogenous guard cell ABA. The model can be used to reconcile proposed cellular mechanisms for guard cell signal transduction with patterns of stomatal movements in leaves.

  15. Signal Transduction Pathways that Regulate CAB Gene Expression

    SciTech Connect

    Chory, Joanne

    2004-12-31

    The process of chloroplast differentiation, involves the coordinate regulation of many nuclear and chloroplast genes. The cues for the initiation of this developmental program are both extrinsic (e.g., light) and intrinsic (cell-type and plastid signals). During this project period, we utilized a molecular genetic approach to select for Arabidopsis mutants that did not respond properly to environmental light conditions, as well as mutants that were unable to perceive plastid damage. These latter mutants, called gun mutants, define two retrograde signaling pathways that regulate nuclear gene expression in response to chloroplasts. A major finding was to identify a signal from chloroplasts that regulates nuclear gene transcription. This signal is the build-up of Mg-Protoporphyrin IX, a key intermediate of the chlorophyll biosynthetic pathway. The signaling pathways downstream of this signal are currently being studied. Completion of this project has provided an increased understanding of the input signals and retrograde signaling pathways that control nuclear gene expression in response to the functional state of chloroplasts. These studies should ultimately influence our abilities to manipulate plant growth and development, and will aid in the understanding of the developmental control of photosynthesis.

  16. Signal Transduction Pathways that Regulate CAB Gene Expression

    SciTech Connect

    Chory, Joanne

    2006-01-16

    The process of chloroplast differentiation, involves the coordinate regulation of many nuclear and chloroplast genes. The cues for the initiation of this developmental program are both extrinsic (e.g., light) and intrinsic (cell-type and plastid signals). During this project period, we utilized a molecular genetic approach to select for Arabidopsis mutants that did not respond properly to environmental light conditions, as well as mutants that were unable to perceive plastid damage. These latter mutants, called gun mutants, define two retrograde signaling pathways that regulate nuclear gene expression in response to chloroplasts. A major finding was to identify a signal from chloroplasts that regulates nuclear gene transcription. This signal is the build-up of Mg-Protoporphyrin IX, a key intermediate of the chlorophyll biosynthetic pathway. The signaling pathways downstream of this signal are currently being studied. Completion of this project has provided an increased understanding of the input signals and retrograde signaling pathways that control nuclear gene expression in response to the functional state of chloroplasts. These studies should ultimately influence our abilities to manipulate plant growth and development, and will aid in the understanding of the developmental control of photosynthesis.

  17. Aureobasidium pullulans xylanase, gene and signal sequence

    DOEpatents

    Li Xinliang; Ljungdahl, L.G.

    1997-01-07

    A xylanase from Aureobasidium pullulans having a high specific activity is provided, as well as a signal protein for controlling excretion into cell culture medium of proteins to which it is attached. DNA encoding these proteins is also provided. 4 figs.

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

    PubMed Central

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

    2016-01-01

    NHL (NDR1/HIN1-like) genes play crucial roles in pathogen induced plant responses to biotic stress. Here, we report the possible function of NHL6 in plant response to abscisic acid (ABA) and abiotic stress. NHL6 was highly expressed in non-germinated seeds, and its expression was strongly induced by ABA and multiple abiotic stress signals. Loss-of-function of NHL6 decreased sensitivity to ABA in the early developmental stages including seed germination and post-germination seedling growth of the nhl6 mutants. However, overexpression of NHL6 increased sensitivity to ABA, salt and osmotic stress of the transgenic plants. Further studies indicated that the increased sensitivity in the 35S::NHL6 overexpressing plants could be a result of both ABA hypersensitivity and increased endogenous ABA accumulation under the stress conditions. It was also seen that the ABA-responsive element binding factors AREB1, AREB2 and ABF3 could regulate NHL6 expression at transcriptional level. Our results indicate that NHL6 plays an important role in the abiotic stresses-induced ABA signaling and biosynthesis, particularly during seed germination and early seedling development in Arabidopsis. PMID:26849212

  19. Loss of heterophylly in aquatic plants: not ABA-mediated stress but exogenous ABA treatment induces stomatal leaves in Potamogeton perfoliatus.

    PubMed

    Iida, Satoko; Ikeda, Miyuki; Amano, Momoe; Sakayama, Hidetoshi; Kadono, Yasuro; Kosuge, Keiko

    2016-09-01

    Heterophyllous aquatic plants produce aerial (i.e., floating and terrestrial) and submerged leaves-the latter lack stomata-while homophyllous plants contain only submerged leaves, and cannot survive on land. To identify whether differences in morphogenetic potential and/or physiological stress responses are responsible for variation in phenotypic plasticity between two plants types, responses to abscisic acid (ABA) and salinity stress were compared between the closely related, but ecologically diverse pondweeds, Potamogeton wrightii (heterophyllous) and P. perfoliatus (homophyllous). The ABA-treated (1 or 10 μM) P. wrightii plants exhibited heterophylly and produced leaves with stomata. The obligate submerged P. perfoliatus plants were able to produce stomata on their leaves, but there were no changes to leaf shape, and stomatal production occurred only at a high ABA concentration (10 μM). Under salinity stress conditions, only P. wrightii leaves formed stomata. Additionally, the expression of stress-responsive NCED genes, which encode a key enzyme in ABA biosynthesis, was consistently up-regulated in P. wrightii, but only temporarily in P. perfoliatus. The observed species-specific gene expression patterns may be responsible for the induction or suppression of stomatal production during exposure to salinity stress. These results suggest that the two Potamogeton species have an innate morphogenetic ability to form stomata, but the actual production of stomata depends on ABA-mediated stress responses specific to each species and habitat.

  20. The dynamic mechanism of noisy signal decoding in gene regulation

    PubMed Central

    Liu, Peijiang; Wang, Haohua; Huang, Lifang; Zhou, Tianshou

    2017-01-01

    Experimental evidence supports that signaling pathways can induce different dynamics of transcription factor (TF) activation, but how an input signal is encoded by such a dynamic, noisy TF and further decoded by downstream genes remains largely unclear. Here, using a system of stochastic transcription with signal regulation, we show that (1) keeping the intensity of the signal noise invariant but prolonging the signal duration can both enhance the mutual information (MI) and reduce the energetic cost (EC); (2) if the signal duration is fixed, the larger MI needs the larger EC, but if the signal period is fixed, there is an optimal time that the signal spends at one lower branch, such that MI reaches the maximum; (3) if both the period and the duration are simultaneously fixed, increasing the input noise can always enhance MI in the case of transcription regulation rather than in the case of degradation regulation. In addition, we find that the input noise can induce stochastic focusing in a regulation-dependent manner. These results reveal not only the dynamic mechanism of noisy signal decoding in gene regulation but also the essential role of external noise in controlling gene expression levels. PMID:28176840

  1. Physiological characteristics and related gene expression of after-ripening on seed dormancy release in rice.

    PubMed

    Du, W; Cheng, J; Cheng, Y; Wang, L; He, Y; Wang, Z; Zhang, H

    2015-11-01

    After-ripening is a common method used for dormancy release in rice. In this study, the rice variety Jiucaiqing (Oryza sativa L. subsp. japonica) was used to determine dormancy release following different after-ripening times (1, 2 and 3 months). Germination speed, germination percentage and seedling emergence increased with after-ripening; more than 95% germination and 85% seedling emergence were observed following 1 month of after-ripening within 10 days of imbibition, compared with <45% germination and 20% seedling emergence in freshly harvested seed. Hence, 3 months of after-ripening could be considered a suitable treatment period for rice dormancy release. Dormancy release by after-ripening is mainly correlated with a rapid decline in ABA content and increase in IAA content during imbibition. Subsequently, GA(1)/ABA, GA(7)/ABA, GA(12)/ABA, GA(20)/ABA and IAA/ABA ratios significantly increased, while GA(3)/ABA, GA(4)/ABA and GAs/IAA ratio significantly decreased in imbibed seeds following 3 months of after-ripening, thereby altering α-amylase activity during seed germination. Peak α-amylase activity occurred at an earlier germination stage in after-ripened seeds than in freshly harvested seeds. Expression of ABA, GA and IAA metabolism genes and dormancy-related genes was regulated by after-ripening time upon imbibition. Expression of OsCYP707A5, OsGA2ox1, OsGA2ox2, OsGA2ox3, OsILR1, OsGH3-2, qLTG3-1 and OsVP1 increased, while expression of Sdr4 decreased in imbibed seeds following 3 months of after-ripening. Dormancy release through after-ripening might be involved in weakening tissues covering the embryo via qLTG3-1 and decreased ABA signalling and sensitivity via Sdr4 and OsVP1.

  2. Transcriptomic Analysis Reveals Possible Influences of ABA on Secondary Metabolism of Pigments, Flavonoids and Antioxidants in Tomato Fruit during Ripening

    PubMed Central

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

    2015-01-01

    Abscisic acid (ABA) has been proven to be involved in the regulation of climacteric fruit ripening, but a comprehensive investigation of its influence on ripening related processes is still lacking. By applying the next generation sequencing technology, we conducted a comparative analysis of the effects of exogenous ABA and NDGA (Nordihydroguaiaretic acid, an inhibitor of ABA biosynthesis) on tomato fruit ripening. The high throughput sequencing results showed that out of the 25728 genes expressed across all three samples, 10388 were identified as significantly differently expressed genes. Exogenous ABA was found to enhance the transcription of genes involved in pigments metabolism, including carotenoids biosynthesis and chlorophyll degradation, whereas NDGA treatment inhibited these processes. The results also revealed the crucial role of ABA in flavonoids synthesis and regulation of antioxidant system. Intriguingly, we also found that an inhibition of endogenous ABA significantly enhanced the transcriptional abundance of genes involved in photosynthesis. Our results highlighted the significance of ABA in regulating tomato ripening, which provided insight into the regulatory mechanism of fruit maturation and senescence process. PMID:26053166

  3. Dynamic subnuclear relocalization of WRKY40, a potential new mechanism of ABA-dependent transcription factor regulation.

    PubMed

    Geilen, Katja; Böhmer, Maik

    2015-01-01

    The phytohormone ABA plays a major role during plant development, e.g. seed maturation and seed germination, and during adaptation to abiotic stresses like stomatal aperture regulation. The three closely related WRKY transcription factors WRKY18, WRKY40 and WRKY60 function in ABA signal transduction. We recently demonstrated that WRKY18 and WRKY40 but not WRKY60 localize to nuclear bodies in A. thaliana mesophyll protoplasts. WRKY40, a negative regulator of ABA-dependent inhibition of seed germination, relocalizes from PNBs to the nucleoplasm in the presence of ABA in a dynamic and phosphorylation-dependent manner. We propose that subnuclear relocalization of WRKY40 might constitute a new regulatory mechanism of ABA-dependent modulation of transcription factor activity.

  4. Expression analysis of genes encoding mitogen-activated protein kinases in maize provides a key link between abiotic stress signaling and plant reproduction.

    PubMed

    Sun, Wei; Chen, Hao; Wang, Juan; Sun, Hong Wei; Yang, Shu Ke; Sang, Ya Lin; Lu, Xing Bo; Xu, Xiao Hui

    2015-01-01

    Mitogen-activated protein kinases (MAPKs) play important roles in stress responses and development in plants. Maize (Zea mays), an important cereal crop, is a model plant species for molecular studies. In the last decade, several MAPKs have been identified in maize; however, their functions have not been studied extensively. Genome-wide identification and expression analysis of maize MAPK genes could provide valuable information for understanding their functions. In this study, 20 non-redundant maize MAPK genes (ZmMPKs) were identified via a genome-wide survey. Phylogenetic analysis of MAPKs from maize, rice (Oryza sativa), Arabidopsis (Arabidopsis thaliana), poplar (Populus trichocarpa), and tomato (Solanum lycopersicum) classified them into four major classes. ZmMPKs in the same class had similar domains, motifs, and genomic structures. Gene duplication investigations suggested that segmental duplications made a large contribution to the expansion of ZmMPKs. A number of cis-acting elements related to plant development and response to stress and hormones were identified in the promoter regions of ZmMPKs. Furthermore, transcript profile analysis in eight tissues and organs at various developmental stages demonstrated that most ZmMPKs were preferentially expressed in reproductive tissues and organs. The transcript abundance of most ZmMPKs changed significantly under salt, drought, cold, or abscisic acid (ABA) treatments, implying that they might participate in abiotic stress and ABA signaling. These expression analyses indicated that ZmMPKs might serve as linkers between abiotic stress signaling and plant reproduction. Our data will deepen our understanding of the complexity of the maize MAPK gene family and provide new clues to investigate their functions.

  5. Interplay between ABA and GA Modulates the Timing of Asymmetric Cell Divisions in the Arabidopsis Root Ground Tissue.

    PubMed

    Lee, Shin Ae; Jang, Sejeong; Yoon, Eun Kyung; Heo, Jung-Ok; Chang, Kwang Suk; Choi, Ji Won; Dhar, Souvik; Kim, Gyuree; Choe, Jeong-Eun; Heo, Jae Bok; Kwon, Chian; Ko, Jae-Heung; Hwang, Yong-Sic; Lim, Jun

    2016-06-06

    In multicellular organisms, controlling the timing and extent of asymmetric cell divisions (ACDs) is crucial for correct patterning. During post-embryonic root development in Arabidopsis thaliana, ground tissue (GT) maturation involves an additional ACD of the endodermis, which generates two different tissues: the endodermis (inner) and the middle cortex (outer). It has been reported that the abscisic acid (ABA) and gibberellin (GA) pathways are involved in middle cortex (MC) formation. However, the molecular mechanisms underlying the interaction between ABA and GA during GT maturation remain largely unknown. Through transcriptome analyses, we identified a previously uncharacterized C2H2-type zinc finger gene, whose expression is regulated by GA and ABA, thus named GAZ (GA- AND ABA-RESPONSIVE ZINC FINGER). Seedlings ectopically overexpressing GAZ (GAZ-OX) were sensitive to ABA and GA during MC formation, whereas GAZ-SRDX and RNAi seedlings displayed opposite phenotypes. In addition, our results indicated that GAZ was involved in the transcriptional regulation of ABA and GA homeostasis. In agreement with previous studies that ABA and GA coordinate to control the timing of MC formation, we also confirmed the unique interplay between ABA and GA and identified factors and regulatory networks bridging the two hormone pathways during GT maturation of the Arabidopsis root.

  6. The ABA receptor PYL9 together with PYL8 plays an important role in regulating lateral root growth

    PubMed Central

    Xing, Lu; Zhao, Yang; Gao, Jinghui; Xiang, Chengbin; Zhu, Jian-Kang

    2016-01-01

    Abscisic acid is a phytohormone regulating plant growth, development and stress responses. PYR1/PYL/RCAR proteins are ABA receptors that function by inhibiting PP2Cs to activate SnRK2s, resulting in phosphorylation of ABFs and other effectors of ABA response pathways. Exogenous ABA induces growth quiescence of lateral roots, which is prolonged by knockout of the ABA receptor PYL8. Among the 14 members of PYR1/PYL/RCAR protein family, PYL9 is a close relative of PYL8. Here we show that knockout of both PYL9 and PYL8 resulted in a longer ABA-induced quiescence on lateral root growth and a reduced sensitivity to ABA on primary root growth and lateral root formation compared to knockout of PYL8 alone. Induced overexpression of PYL9 promoted the lateral root elongation in the presence of ABA. The prolonged quiescent phase of the pyl8-1pyl9 double mutant was reversed by exogenous IAA. PYL9 may regulate auxin-responsive genes in vivo through direct interaction with MYB77 and MYB44. Thus, PYL9 and PYL8 are both responsible for recovery of lateral root from ABA inhibition via MYB transcription factors. PMID:27256015

  7. Overexpression of MpCYS4, A Phytocystatin Gene from Malus prunifolia (Willd.) Borkh., Enhances Stomatal Closure to Confer Drought Tolerance in Transgenic Arabidopsis and Apple

    PubMed Central

    Tan, Yanxiao; Li, Mingjun; Yang, Yingli; Sun, Xun; Wang, Na; Liang, Bowen; Ma, Fengwang

    2017-01-01

    Phytocystatins (PhyCys) comprise a group of inhibitors for cysteine proteinases in plants. They play a wide range of important roles in regulating endogenous processes and protecting plants against various environmental stresses, but the underlying mechanisms remain largely unknown. Here, we detailed the biological functions of MpCYS4, a member of cystatin genes isolated from Malus prunifolia. This gene was activated under water deficit, heat (40°C), exogenous abscisic acid (ABA), or methyl viologen (MV) (Tan et al., 2014a). At cellular level, MpCYS4 protein was found to be localized in the nucleus, cytoplasm, and plasma membrane of onion epidermal cells. Recombinant MpCYS4 cystatin expressed in Escherichia coli was purified and it exhibited cysteine protease inhibitor activity. Transgenic overexpression of MpCYS4 in Arabidopsis (Arabidopsis thaliana) and apple (Malus domestica) led to ABA hypersensitivity and series of ABA-associated phenotypes, such as enhanced ABA-induced stomatal closing, altered expression of many ABA/stress-responsive genes, and enhanced drought tolerance. Taken together, our results demonstrate that MpCYS4 is involved in ABA-mediated stress signal transduction and confers drought tolerance at least in part by enhancing stomatal closure and up-regulating the transcriptional levels of ABA- and drought-related genes. These findings provide new insights into the molecular mechanisms by which phytocystatins influence plant growth, development, and tolerance to stress. PMID:28174579

  8. Overexpression of MpCYS4, A Phytocystatin Gene from Malus prunifolia (Willd.) Borkh., Enhances Stomatal Closure to Confer Drought Tolerance in Transgenic Arabidopsis and Apple.

    PubMed

    Tan, Yanxiao; Li, Mingjun; Yang, Yingli; Sun, Xun; Wang, Na; Liang, Bowen; Ma, Fengwang

    2017-01-01

    Phytocystatins (PhyCys) comprise a group of inhibitors for cysteine proteinases in plants. They play a wide range of important roles in regulating endogenous processes and protecting plants against various environmental stresses, but the underlying mechanisms remain largely unknown. Here, we detailed the biological functions of MpCYS4, a member of cystatin genes isolated from Malus prunifolia. This gene was activated under water deficit, heat (40°C), exogenous abscisic acid (ABA), or methyl viologen (MV) (Tan et al., 2014a). At cellular level, MpCYS4 protein was found to be localized in the nucleus, cytoplasm, and plasma membrane of onion epidermal cells. Recombinant MpCYS4 cystatin expressed in Escherichia coli was purified and it exhibited cysteine protease inhibitor activity. Transgenic overexpression of MpCYS4 in Arabidopsis (Arabidopsis thaliana) and apple (Malus domestica) led to ABA hypersensitivity and series of ABA-associated phenotypes, such as enhanced ABA-induced stomatal closing, altered expression of many ABA/stress-responsive genes, and enhanced drought tolerance. Taken together, our results demonstrate that MpCYS4 is involved in ABA-mediated stress signal transduction and confers drought tolerance at least in part by enhancing stomatal closure and up-regulating the transcriptional levels of ABA- and drought-related genes. These findings provide new insights into the molecular mechanisms by which phytocystatins influence plant growth, development, and tolerance to stress.

  9. Cross-talk modulation between ABA and ethylene by transcription factor SlZFP2 during fruit development and ripening in tomato.

    PubMed

    Weng, Lin; Zhao, Fangfang; Li, Rong; Xiao, Han

    2015-01-01

    The stress hormone ABA not only regulates stress response, but is also required for plant development and growth. Some evidences indicate that ABA plays a pivotal role in the ripening process of non climacteric as well as climacteric fruits. In a recent study, we showed that the tomato (Solanum lycopersicum) transcription factor SlZFP2 fine tunes ABA biosynthesis during fruit development through direct suppression of ABA biosynthetic genes and it also regulates fruit ripening through transcriptional suppression of the ripening regulator CNR. This indicates that SlZFP2 likely modulates the cross-talk between ABA and ethylene in regulation of fruit development and ripening in tomato. Gene expression analysis using ABA deficient mutants sit and flc as well as the SlZFP2 RNAi lines of high fruit ABA production showed that ethylene biosynthetic genes LeACS1A, LeACS1 and LeACO1 were positively regulated by ABA during early fruit growth. We reason that ABA promotes basal ethylene biosynthesis in system 1 during fruit growth and likely plays a minor role in ripening regulation after the onset of ripening process.

  10. Abscisic acid-regulated responses of aba2-1 under osmotic stress: the abscisic acid-inducible antioxidant defence system and reactive oxygen species production.

    PubMed

    Ozfidan, C; Turkan, I; Sekmen, A H; Seckin, B

    2012-03-01

    We investigated the interaction among abscisic acid (ABA), reactive oxygen species (ROS) and antioxidant defence system in the transduction of osmotic stress signalling using Arabidopsis thaliana WT (Columbia ecotype, WT) and an ABA-deficient mutant (aba2-1). For this, 50 μm ABA and osmotic stress, induced with 40% (w/v) polyethylene glycol (PEG8000; -0.7 MPa), were applied to WT and aba2-1 for 6, 12 or 24 h. Time course analysis was undertaken for determination of total/isoenzyme activity of the antioxidant enzymes, superoxide dismutase (SOD; EC 1.15.1.1), catalase (CAT; EC 1.11.1.6), ascorbate peroxidase (APX; EC 1.11.1.11), NADPH oxidase (NOX; EC 1.6.3.1) activity; scavenging activity of the hydroxyl radical (OH˙), hydrogen peroxide (H(2) O(2) ); endogenous ABA and malondialdehyde (MDA). The highest H(2) O(2) and MDA content was found in PEG-treated groups of both genotypes, but with more in aba2-1. ABA treatment under stress reduced the accumulation of H(2) O(2) and MDA, while it promoted activity of SOD, CAT and APX. APX activity was higher than CAT activity in ABA-treated WT and aba2-1, indicating a protective role of APX rather than CAT during osmotic stress-induced oxidative damage. Treatment with ABA also significantly induced increased NOX activity. Oxidative damage was lower in ABA-treated seedlings of both genotypes, which was associated with greater activity of SOD (Mn-SOD1 and 2 and Fe-SOD isoenzymes), CAT and APX in these seedlings after 24 h of stress. These results suggest that osmotic stress effects were overcome by ABA treatment because of increased SOD, CAT, APX and NOX.

  11. Gene profiling of the red light signalling pathways in roots.

    PubMed

    Molas, Maria Lia; Kiss, John Z; Correll, Melanie J

    2006-01-01

    Red light, acting through the phytochromes, controls numerous aspects of plant development. Many of the signal transduction elements downstream of the phytochromes have been identified in the aerial portions of the plant; however, very few elements in red-light signalling have been identified specifically for roots. Gene profiling studies using microarrays and quantitative Real-Time PCR were performed to characterize gene expression changes in roots of Arabidopsis seedlings exposed to 1 h of red light. Several factors acting downstream of phytochromes in red-light signalling in roots were identified. Some of the genes found to be differentially expressed in this study have already been characterized in the red-light-signalling pathway for whole plants. For example, PHYTOCHROME KINASE 1 (PKS1), LONG HYPOCOTYL 5 (HY5), EARLY FLOWERING 4 (ELF4), and GIGANTEA (GI) were all significantly up-regulated in roots of seedlings exposed to 1 h of red light. The up-regulation of SUPPRESSOR OF PHYTOCHROME A RESPONSES 1 (SPA1) and CONSTITUTIVE PHOTOMORPHOGENIC 1-like (COP1-like) genes suggests that the PHYA-mediated pathway was attenuated by red light. In addition, genes involved in lateral root and root hair formation, root plastid development, phenylpropanoid metabolism, and hormone signalling were also regulated by exposure to red light. Interestingly, members of the RPT2/NPH3 (ROOT PHOTOTROPIC 2/NON PHOTOTROPIC HYPOCOTYL 3) family, which have been shown to mediate blue-light-induced phototropism, were also differentially regulated in roots in red light. Therefore, these results suggest that red and blue light pathways interact in roots of seedlings and that many elements involved in red-light-signalling found in the aerial portions of the plant are differentially expressed in roots within 1 h of red light exposure.

  12. Evolutionarily conserved regulatory mechanisms of abscisic acid signaling in land plants: characterization of ABSCISIC ACID INSENSITIVE1-like type 2C protein phosphatase in the liverwort Marchantia polymorpha.

    PubMed

    Tougane, Ken; Komatsu, Kenji; Bhyan, Salma Begum; Sakata, Yoichi; Ishizaki, Kimitsune; Yamato, Katsuyuki T; Kohchi, Takayuki; Takezawa, Daisuke

    2010-03-01

    Abscisic acid (ABA) is postulated to be a ubiquitous hormone that plays a central role in seed development and responses to environmental stresses of vascular plants. However, in liverworts (Marchantiophyta), which represent the oldest extant lineage of land plants, the role of ABA has been least emphasized; thus, very little information is available on the molecular mechanisms underlying ABA responses. In this study, we isolated and characterized MpABI1, an ortholog of ABSCISIC ACID INSENSITIVE1 (ABI1), from the liverwort Marchantia polymorpha. The MpABI1 cDNA encoded a 568-amino acid protein consisting of the carboxy-terminal protein phosphatase 2C (PP2C) domain and a novel amino-terminal regulatory domain. The MpABI1 transcript was detected in the gametophyte, and its expression level was increased by exogenous ABA treatment in the gemma, whose growth was strongly inhibited by ABA. Experiments using green fluorescent protein fusion constructs indicated that MpABI1 was mainly localized in the nucleus and that its nuclear localization was directed by the amino-terminal domain. Transient overexpression of MpABI1 in M. polymorpha and Physcomitrella patens cells resulted in suppression of ABA-induced expression of the wheat Em promoter fused to the beta -glucuronidase gene. Transgenic P. patens expressing MpABI1 and its mutant construct, MpABI1-d2, lacking the amino-terminal domain, had reduced freezing and osmotic stress tolerance, and associated with reduced accumulation of ABA-induced late embryogenesis abundant-like boiling-soluble proteins. Furthermore, ABA-induced morphological changes leading to brood cells were not prominent in these transgenic plants. These results suggest that MpABI1 is a negative regulator of ABA signaling, providing unequivocal molecular evidence of PP2C-mediated ABA response mechanisms functioning in liverworts.

  13. Interaction between composite elements in the napA promoter: both the B-box ABA-responsive complex and the RY/G complex are necessary for seed-specific expression.

    PubMed

    Ezcurra, I; Ellerström, M; Wycliffe, P; Stålberg, K; Rask, L

    1999-07-01

    During seed maturation, the transcriptional activity of napin genes is regulated by developmental signals involving the transcriptional activator ABI3 and abscisic acid (ABA). To localize cis elements involved in the seed-specific activity of the napin napA promoter, a systematic analysis was performed focusing on two major element complexes, the B-box and RY/G. Substitution mutation analysis using promoter-reporter gene fusions in stable transgenic tobacco showed synergistic interactions between elements within these complexes. The distal part of the B-box shows similarities to abscisic acid response elements and the proximal portion contains a CA-rich element. In vitro studies involving Exonuclease III protection and electrophoretic mobility shift assays revealed binding by nuclear proteins to elements within the B-box. The distal and proximal parts of the B-box were found to bind distinct nuclear protein complexes. By gain-of-function analysis with a tetramer of the B-box fused to a truncated (-46) cauliflower mosaic virus (CaMV) 35S minimal promoter, it was demonstrated that the B-box mediates strong activity in seeds. Further, it was shown that the elements in the B-box constitute an ABA-responsive complex, since the B-box tetramer mediates ABA-responsiveness in vegetative tissues to a construct containing the CaMV virus 35S enhancer (-343 to -90). Thus, the seed-specific activity of the napA promoter relies on the combinatorial interaction between the RY/G complex and the B-box ABA-responsive complex during the ABA response in seed development.

  14. Insulin signal transduction pathways and insulin-induced gene expression.

    PubMed

    Keeton, Adam B; Amsler, Maggie O; Venable, Derwei Y; Messina, Joseph L

    2002-12-13

    Insulin regulates metabolic activity, gene transcription, and cell growth by modulating the activity of several intracellular signaling pathways. Insulin activation of one mitogen-activated protein kinase cascade, the MEK/ERK kinase cascade, is well described. However, the effect of insulin on the parallel p38 pathway is less well understood. The present work examines the effect of inhibiting the p38 signaling pathway by use of specific inhibitors, either alone or in combination with insulin, on the activation of ERK1/2 and on the regulation of gene transcription in rat hepatoma cells. Activation of ERK1/2 was induced by insulin and was dependent on the activation of MEK1, the kinase upstream of ERK in this pathway. Treatment of cells with p38 inhibitors also induced ERK1/2 activation/phosphorylation. The addition of p38 inhibitors followed by insulin addition resulted in a greater than additive activation of ERK1/2. The two genes studied, c-Fos and Pip92, are immediate-early genes that are dependent on the ERK1/2 pathway for insulin-regulated induction because the insulin effect was inhibited by pretreatment with a MEK1 inhibitor. The addition of p38 inhibitors induced transcription of both genes in a dose-dependent manner, and insulin stimulation of both genes was enhanced by prior treatment with p38 inhibitors. The ability of the p38 inhibitors to induce ERK1/2 and gene transcription, both alone and in combination with insulin, was abolished by prior inhibition of MEK1. These data suggest possible cross-talk between the p38 and ERK1/2 signaling pathways and a potential role of p38 in insulin signaling.

  15. Optically Pure Abscisic Acid Analogs—Tools for Relating Germination Inhibition and Gene Expression in Wheat Embryos 1

    PubMed Central

    Walker-Simmons, M. K.; Anderberg, Robert J.; Rose, Patricia A.; Abrams, Suzanne R.

    1992-01-01

    We report an examination of the structural requirements of the abscisic acid (ABA) recognition response in wheat dormant seed embryos using optically pure isomers of ABA analogs. These compounds include permutations to the ABA structure with either an acetylene or a trans bond at C-4 C-5, and either a single or double bond at the C-2′ C-3′ double bond. (R)-ABA and the three isomers with the same configuration at C-1′ as natural ABA were found to be effective germination inhibitors. The biologically active ABA analogs exhibited differential effects on ABA-responsive gene expression. All the ABA analogs that inhibited germination induced two ABA-responsive genes, wheat group 3 lea and dhn (rab). However, (R)-ABA and (S)-dihydroABA were less effective in inducing the ABA-responsive gene Em within the time that embryonic germination was inhibited. ImagesFigure 3Figure 4 PMID:16668914

  16. Sap fluxes from different parts of the rootzone modulate xylem ABA concentration during partial rootzone drying and re-wetting.

    PubMed

    Pérez-Pérez, J G; Dodd, I C

    2015-04-01

    Previous studies with partial rootzone drying (PRD) irrigation demonstrated that alternating the wet and dry parts of the rootzone (PRD-Alternated) increased leaf xylem ABA concentration ([X-ABA]leaf) compared with maintaining the same wet and dry parts of the rootzone (PRD-Fixed). To determine the relative contributions of different parts of the rootzone to this ABA signal, [X-ABA]leaf of potted, split-root tomato (Solanum lycopersicum) plants was modelled by quantifying the proportional water uptake from different soil compartments, and [X-ABA]leaf responses to the entire pot soil-water content (θpot). Continuously measuring soil-moisture depletion by, or sap fluxes from, different parts of the root system revealed that water uptake rapidly declined (within hours) after withholding water from part of the rootzone, but was rapidly restored (within minutes) upon re-watering. Two hours after re-watering part of the rootzone, [X-ABA]leaf was equally well predicted according to θpot alone and by accounting for the proportional water uptake from different parts of the rootzone. Six hours after re-watering part of the rootzone, water uptake by roots in drying soil was minimal and, instead, occurred mainly from the newly irrigated part of the rootzone, thus [X-ABA]leaf was best predicted by accounting for the proportional water uptake from different parts of the rootzone. Contrary to previous results, alternating the wet and dry parts of the rootzone did not enhance [X-ABA]leaf compared with PRD-Fixed irrigation. Further work is required to establish whether altered root-to-shoot ABA signalling contributes to the improved yields of crops grown with alternate, rather than fixed, PRD.

  17. Genetic Analysis of Physcomitrella patens Identifies ABSCISIC ACID NON-RESPONSIVE, a Regulator of ABA Responses Unique to Basal Land Plants and Required for Desiccation Tolerance.

    PubMed

    Stevenson, Sean R; Kamisugi, Yasuko; Trinh, Chi H; Schmutz, Jeremy; Jenkins, Jerry W; Grimwood, Jane; Muchero, Wellington; Tuskan, Gerald A; Rensing, Stefan A; Lang, Daniel; Reski, Ralf; Melkonian, Michael; Rothfels, Carl J; Li, Fay-Wei; Larsson, Anders; Wong, Gane K-S; Edwards, Thomas A; Cuming, Andrew C

    2016-06-01

    The anatomically simple plants that first colonized land must have acquired molecular and biochemical adaptations to drought stress. Abscisic acid (ABA) coordinates responses leading to desiccation tolerance in all land plants. We identified ABA nonresponsive mutants in the model bryophyte Physcomitrella patens and genotyped a segregating population to map and identify the ABA NON-RESPONSIVE (ANR) gene encoding a modular protein kinase comprising an N-terminal PAS domain, a central EDR domain, and a C-terminal MAPKKK-like domain. anr mutants fail to accumulate dehydration tolerance-associated gene products in response to drought, ABA, or osmotic stress and do not acquire ABA-dependent desiccation tolerance. The crystal structure of the PAS domain, determined to 1.7-Å resolution, shows a conserved PAS-fold that dimerizes through a weak dimerization interface. Targeted mutagenesis of a conserved tryptophan residue within the PAS domain generates plants with ABA nonresponsive growth and strongly attenuated ABA-responsive gene expression, whereas deleting this domain retains a fully ABA-responsive phenotype. ANR orthologs are found in early-diverging land plant lineages and aquatic algae but are absent from more recently diverged vascular plants. We propose that ANR genes represent an ancestral adaptation that enabled drought stress survival of the first terrestrial colonizers but were lost during land plant evolution.

  18. Genetic analysis of Physcomitrella patens identifies ABSCISIC ACID NON-RESPONSIVE, a regulator of ABA responses unique to basal land plants and required for desiccation tolerance

    DOE PAGES

    Stevenson, Sean Ross; Kamisugi, Yasuko; Trinh, Chi H.; ...

    2016-05-18

    The anatomically simple plants that first colonized land must have acquired molecular and biochemical adaptations to drought stress. Abscisic acid (ABA) coordinates responses leading to desiccation tolerance in all land plants. We identified ABA nonresponsive mutants in the model bryophyte Physcomitrella patens and genotyped a segregating population to map and identify the ABA NON-RESPONSIVE (ANR) gene encoding a modular protein kinase comprising an N-terminal PAS domain, a central EDR domain, and a C-terminal MAPKKK-like domain. anr mutants fail to accumulate dehydration tolerance-associated gene products in response to drought, ABA, or osmotic stress and do not acquire ABA-dependent desiccation tolerance. Themore » crystal structure of the PAS domain, determined to 1.7-Å resolution, shows a conserved PAS-fold that dimerizes through a weak dimerization interface. Targeted mutagenesis of a conserved tryptophan residue within the PAS domain generates plants with ABA nonresponsive growth and strongly attenuated ABA-responsive gene expression, whereas deleting this domain retains a fully ABA-responsive phenotype. ANR orthologs are found in early-diverging land plant lineages and aquatic algae but are absent from more recently diverged vascular plants. Lastly, we propose that ANR genes represent an ancestral adaptation that enabled drought stress survival of the first terrestrial colonizers but were lost during land plant evolution.« less

  19. Is the ABA concentration in the sap collected by pressurizing leaves relevant for analysing drought effects on stomata? Evidence from ABA-fed leaves of transgenic plants with modified capacities to synthesize ABA.

    PubMed

    Borel, Charlotte; Simonneau, Thierry

    2002-02-01

    Most studies on the role of ABA in the stomatal response of the whole plant to drought rely on a good estimate of ABA concentration in xylem sap. In this report, varying volumes of sap (V(sap)) were collected by pressurizing leaves cut from several lines of N. plumbaginifolia with modified capacities to synthesize ABA. Leaves were fed with solutions of known ABA concentration ([ABA](solution) from 0-500 micromol m(-3)) for 2-3 h before sap collection. ABA concentration in extruded sap ([ABA](sap)) was compared with [ABA](solution). In low-volume extracts (less than 0.35 mm(3) cm(-2) leaf area) collected from leaves of well-watered plants, [ABA](sap) was close to [ABA](solution). For all lines, [ABA](sap) decreased with increasing V(sap). The same dilution effect was observed for leaves pressurized just after sampling on droughted plants, suggesting, as for detached leaves fed with ABA, that [ABA](sap) in low-volume extracts approximated well with the concentration of ABA entering leaves still attached on droughted plants. However, ABA-fed leaves sampled from droughted plants yielded higher [ABA](sap) than ABA-fed leaves sampled from well-watered plants. [ABA](sap) was also increased, although very slightly, when leaves were preincubated in highly enriched ABA solution. This indicates that some leaf ABA contributed to the ABA concentration returned in the extruded sap. Consistently, [ABA](sap) in medium-volume extracts (0.35-0.65 mm(3) cm(-2) leaf area) was lower for leaves sampled on under-producing lines than on the wild type. Despite these distortions between [ABA](solution) and [ABA](sap) in medium-volume extracts, stomatal conductance of ABA-fed leaves closely correlated with [ABA](sap) with a similar relationship in all cases, whilst relationships with [ABA](solution) were more scattered.

  20. Bradyoxetin, a unique chemical signal involved in symbiotic gene regulation

    PubMed Central

    Loh, John; Carlson, Russell W.; York, William S.; Stacey, Gary

    2002-01-01

    Bradyrhizobium japonicum is a symbiotic bacterium that nodulates soybean. Critical for the infection and establishment of this symbiosis are the bacterial nodulation genes (nod, nol, noe), which are induced in the presence of plant produced isoflavones. Transcription of the nodulation genes is also controlled in a population density-dependent fashion. Expression of the nod genes is maximal at low population densities, and decreases significantly at higher culture densities. Population density control of the nodulation genes involves NolA and NodD2, both of which function in tandem to repress nod gene expression. An extracellular secreted factor (CDF) is known to mediate this repression. Here, we report that CDF is a novel signaling molecule, designated bradyoxetin, different from other Gram-negative quorum signals. The proposed structure of bradyoxetin is 2-{4-[[4-(3-aminooxetan-2-yl)phenyl](imino)methyl]phenyl}oxetan-3-ylamine. Interestingly, expression of bradyoxetin is iron-regulated, and is maximally produced under iron-starved conditions. Consistent with this, expression of the nodulation genes occurred in an iron-dependent fashion. Addition of iron to B. japonicum cultures at high optical densities resulted in decreased bradyoxetin production, and a concomitant reduction in nolA expression. A corresponding increase in nodY–lacZ expression was observed with iron treatment. PMID:12393811

  1. Abscisic acid (ABA) receptors: light at the end of the tunnel

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The plant hormone abscisic acid (ABA) plays a role in several aspects of plant growth and development. Understanding how this hormonal stimulus is sensed and transduced turned out to be one of the major tasks in the field of plant signaling. A series of recent papers proposed several different prote...

  2. ABA control of plant macroelement membrane transport systems in response to water deficit and high salinity.

    PubMed

    Osakabe, Yuriko; Yamaguchi-Shinozaki, Kazuko; Shinozaki, Kazuo; Tran, Lam-Son Phan

    2014-04-01

    Plant growth and productivity are adversely affected by various abiotic stressors and plants develop a wide range of adaptive mechanisms to cope with these adverse conditions, including adjustment of growth and development brought about by changes in stomatal activity. Membrane ion transport systems are involved in the maintenance of cellular homeostasis during exposure to stress and ion transport activity is regulated by phosphorylation/dephosphorylation networks that respond to stress conditions. The phytohormone abscisic acid (ABA), which is produced rapidly in response to drought and salinity stress, plays a critical role in the regulation of stress responses and induces a series of signaling cascades. ABA signaling involves an ABA receptor complex, consisting of an ABA receptor family, phosphatases and kinases: these proteins play a central role in regulating a variety of diverse responses to drought stress, including the activities of membrane-localized factors, such as ion transporters. In this review, recent research on signal transduction networks that regulate the function ofmembrane transport systems in response to stress, especially water deficit and high salinity, is summarized and discussed. The signal transduction networks covered in this review have central roles in mitigating the effect of stress by maintaining plant homeostasis through the control of membrane transport systems.

  3. Ca2+ signaling, genes and the cell cycle

    PubMed Central

    Machaca, Khaled

    2013-01-01

    Changes in the concentration and spatial distribution of Ca2+ ions in the cytoplasm constitute a ubiquitous intracellular signaling module in cellular physiology. With the advent of Ca2+ dyes that allow direct visualization of Ca2+ transients, combined with powerful experimental tools such as electrophysiological recordings, intracellular Ca2+ transients have been implicated in practically every aspect of cellular physiology, including cellular proliferation. Ca2+ signals are associated with different phases of the cell cycle and interfering with Ca2+ signaling or downstream pathways often disrupts progression of the cell cycle. Although there exists a dependence between Ca2+ signals and the cell cycle the mechanisms involved are not well defined and given the cross-talk between Ca2+ and other signaling modules, it is difficult to assess the exact role of Ca2+ signals in cell cycle progression. Two exceptions however, include fertilization and T-cell activation, where well-defined roles for Ca2+ signals in mediating progression through specific stages of the cell cycle have been clearly established. In the case of T-cell activation Ca2+ regulates entry into the cell cycle through the induction of gene transcription. PMID:21084120

  4. Interplay between ABA and phospholipases A(2) and D in the response of citrus fruit to postharvest dehydration.

    PubMed

    Romero, Paco; Gandía, Mónica; Alférez, Fernando

    2013-09-01

    The interplay between abscisic acid (ABA) and phospholipases A2 and D (PLA2 and PLD) in the response of citrus fruit to water stress was investigated during postharvest by using an ABA-deficient mutant from 'Navelate' orange named 'Pinalate'. Fruit from both varieties harvested at two different maturation stages (mature-green and full-mature) were subjected to prolonged water loss inducing stem-end rind breakdown (SERB) in full-mature fruit. Treatment with PLA2 inhibitor aristolochic acid (AT) and PLD inhibitor lysophosphatidylethanolamine (LPE) reduced the disorder in both varieties, suggesting that phospholipid metabolism is involved in citrus peel quality. Expression of CsPLDα and CsPLDβ, and CssPLA2α and CssPLA2β was studied by real-time RT-PCR during water stress and in response to ABA. CsPLDα expression increased in mature-green fruit from 'Navelate' but not in 'Pinalate' and ABA did not counteract this effect. ABA enhanced repression of CsPLDα in full-mature fruit. CsPLDβ gene expression decreased in mature-green 'Pinalate', remained unchanged in 'Navelate' and was induced in full-mature fruit from both varieties. CssPLA2α expression increased in mature-green fruit from both varieties whereas in full-mature fruit only increased in 'Navelate'. CssPLA2β expression increased in mature-green flavedo from both varieties, but in full-mature fruit remained steady in 'Navelate' and barely increased in 'Pinalate' fruit. ABA reduced expression in both after prolonged storage. Responsiveness to ABA increased with maturation. Our results show interplay between PLA2 and PLD and suggest that ABA action is upstream phospholipase activation. Response to ABA during water stress in citrus is regulated during fruit maturation and involves membrane phospholipid degradation.

  5. FIA functions as an early signal component of abscisic acid signal cascade in Vicia faba guard cells.

    PubMed

    Sugiyama, Yusuke; Uraji, Misugi; Watanabe-Sugimoto, Megumi; Okuma, Eiji; Munemasa, Shintaro; Shimoishi, Yasuaki; Nakamura, Yoshimasa; Mori, Izumi C; Iwai, Sumio; Murata, Yoshiyuki

    2012-02-01

    An abscisic acid (ABA)-insensitive Vicia faba mutant, fia (fava bean impaired in ABA-induced stomatal closure) had previously been isolated. In this study, it was investigated how FIA functions in ABA signalling in guard cells of Vicia faba. Unlike ABA, methyl jasmonate (MeJA), H(2)O(2), and nitric oxide (NO) induced stomatal closure in the fia mutant. ABA did not induce production of either reactive oxygen species or NO in the mutant. Moreover, ABA did not suppress inward-rectifying K(+) (K(in)) currents or activate ABA-activated protein kinase (AAPK) in mutant guard cells. These results suggest that FIA functions as an early signal component upstream of AAPK activation in ABA signalling but does not function in MeJA signalling in guard cells of Vicia faba.

  6. Estrogen Signaling Multiple Pathways to Impact Gene Transcription

    PubMed Central

    Marino, Maria; Galluzzo, Paola; Ascenzi, Paolo

    2006-01-01

    Steroid hormones exert profound effects on cell growth, development, differentiation, and homeostasis. Their effects are mediated through specific intracellular steroid receptors that act via multiple mechanisms. Among others, the action mechanism starting upon 17β-estradiol (E2) binds to its receptors (ER) is considered a paradigmatic example of how steroid hormones function. Ligand-activated ER dimerizes and translocates in the nucleus where it recognizes specific hormone response elements located in or near promoter DNA regions of target genes. Behind the classical genomic mechanism shared with other steroid hormones, E2 also modulates gene expression by a second indirect mechanism that involves the interaction of ER with other transcription factors which, in turn, bind their cognate DNA elements. In this case, ER modulates the activities of transcription factors such as the activator protein (AP)-1, nuclear factor-κB (NF-κB) and stimulating protein-1 (Sp-1), by stabilizing DNA-protein complexes and/or recruiting co-activators. In addition, E2 binding to ER may also exert rapid actions that start with the activation of a variety of signal transduction pathways (e.g. ERK/MAPK, p38/MAPK, PI3K/AKT, PLC/PKC). The debate about the contribution of different ER-mediated signaling pathways to coordinate the expression of specific sets of genes is still open. This review will focus on the recent knowledge about the mechanism by which ERs regulate the expression of target genes and the emerging field of integration of membrane and nuclear receptor signaling, giving examples of the ways by which the genomic and non-genomic actions of ERs on target genes converge. PMID:18369406

  7. Wnt signaling in heart valve development and osteogenic gene induction

    PubMed Central

    Alfieri, Christina M.; Cheek, Jonathan; Chakraborty, Santanu; Yutzey, Katherine E.

    2009-01-01

    Wnt signaling mediated by beta-catenin has been implicated in early endocardial cushion development, but its roles in later stages of heart valve maturation and homeostasis have not been identified. Multiple Wnt ligands and pathway genes are differentially expressed during heart valve development. At E12.5, Wnt2 is expressed in cushion mesenchyme, whereas Wnt4 and Wnt9b are predominant in overlying endothelial cells. At E17.5, both Wnt3a and Wnt7b are expressed in the remodeling atrioventricular (AV) and semilunar valves. In addition, the TOPGAL Wnt reporter transgene is active throughout the developing AV and semilunar valves at E16.5, with more localized expression in the stratified valve leaflets after birth. In chicken embryo aortic valves, genes characteristic of osteogenic cell lineages including periostin, osteonectin, and Id2 are expressed specifically in the collagen-rich fibrosa layer at E14. Treatment of E14 aortic valve interstitial cells (VIC) in culture with osteogenic media results in increased expression of multiple genes associated with bone formation. Treatment of VIC with Wnt3a leads to nuclear localization of beta-catenin and induction of periostin and matrix gla-protein, but does not induce genes associated with later stages of osteogenesis. Together, these studies provide evidence for Wnt signaling as a regulator of endocardial cushion maturation as well as valve leaflet stratification, homeostasis and pathogenesis. PMID:19961844

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

    PubMed Central

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

    2017-01-01

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

  9. Signalling of abscisic acid to regulate plant growth.

    PubMed Central

    Himmelbach, A; Iten, M; Grill, E

    1998-01-01

    Abscisic acid (ABA) mediated growth control is a fundamental response of plants to adverse environmental cues. The linkage between ABA perception and growth control is currently being unravelled by using different experimental approaches such as mutant analysis and microinjection experiments. So far, two protein phosphatases, ABI1 and ABI2, cADPR, pH, and Ca2+ have been identified as main components of the ABA signalling pathway. Here, the ABA signal transduction pathway is compared to signalling cascades from yeast and mammalian cells. A model for a bifurcated ABA signal transduction pathway exerting a positive and negative control mechanism is proposed. PMID:9800207

  10. Gene transcriptional networks integrate microenvironmental signals in human breast cancer.

    PubMed

    Xu, Ren; Mao, Jian-Hua

    2011-04-01

    A significant amount of evidence shows that microenvironmental signals generated from extracellular matrix (ECM) molecules, soluble factors, and cell-cell adhesion complexes cooperate at the extra- and intracellular level. This synergetic action of microenvironmental cues is crucial for normal mammary gland development and breast malignancy. To explore how the microenvironmental genes coordinate in human breast cancer at the genome level, we have performed gene co-expression network analysis in three independent microarray datasets and identified two microenvironment networks in human breast cancer tissues. Network I represents crosstalk and cooperation of ECM microenvironment and soluble factors during breast malignancy. The correlated expression of cytokines, chemokines, and cell adhesion proteins in Network II implicates the coordinated action of these molecules in modulating the immune response in breast cancer tissues. These results suggest that microenvironmental cues are integrated with gene transcriptional networks to promote breast cancer development.

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

    PubMed

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

    2016-01-01

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

  12. Molecular Characterization of a Strawberry FaASR Gene in Relation to Fruit Ripening

    PubMed Central

    Jiang, Yue-ming; Zhao, Ming-lei; Shan, Wei; Kuang, Jian-fei; Lu, Wang-jin

    2011-01-01

    Background ABA-, stress- and ripening-induced (ASR) proteins have been reported to act as a downstream component involved in ABA signal transduction. Although much attention has been paid to the roles of ASR in plant development and stress responses, the mechanisms by which ABA regulate fruit ripening at the molecular level are not fully understood. In the present work, a strawberry ASR gene was isolated and characterized (FaASR), and a polyclonal antibody against FaASR protein was prepared. Furthermore, the effects of ABA, applied to two different developmental stages of strawberry, on fruit ripening and the expression of FaASR at transcriptional and translational levels were investigated. Methodology/Principal Findings FaASR, localized in the cytoplasm and nucleus, contained 193 amino acids and shared common features with other plant ASRs. It also functioned as a transcriptional activator in yeast with trans-activation activity in the N-terminus. During strawberry fruit development, endogenous ABA content, levels of FaASR mRNA and protein increased significantly at the initiation of ripening at a white (W) fruit developmental stage. More importantly, application of exogenous ABA to large green (LG) fruit and W fruit markedly increased endogenous ABA content, accelerated fruit ripening, and greatly enhanced the expression of FaASR transcripts and the accumulation of FaASR protein simultaneously. Conclusions These results indicate that FaASR may be involved in strawberry fruit ripening. The observed increase in endogenous ABA content, and enhanced FaASR expression at transcriptional and translational levels in response to ABA treatment might partially contribute to the acceleration of strawberry fruit ripening. PMID:21915355

  13. Cloning and characterization of a novel Gladiolus hybridus AFP family gene (GhAFP-like) related to corm dormancy.

    PubMed

    Wu, Jian; Seng, Shanshan; Carianopol, Carina; Sui, Juanjuan; Yang, Qiuyan; Zhang, Fengqin; Jiang, Huiru; He, Junna; Yi, Mingfang

    2016-02-26

    Abscisic acid (ABA) is an important phytohormone controlling seed dormancy. AFPs (ABA INSENSITIVE FIVE BINDING PROTEINS) are reported to be negative regulators of the ABA signaling pathway. The involvement of AFPs in dormant vegetative organs remains poorly understood. Here, we isolated and characterized a novel AFP family member from Gladiolus dormant cormels, GhAFP-like, containing three conserved domains of the AFP family. Quantitative PCR analysis revealed that GhAFP-like was expressed in dormant organs and its expression was down-regulated along with corm storage. GhAFP-like was verified to be a nuclear-localized protein. Overexpressing GhAFP-like in Arabidopsis thaliana not only showed weaker seed dormancy with insensitivity to ABA, but also changed the expression of some ABA related genes. In addition, a primary root elongation assay showed GhAFP-like may involve in auxin signaling response. The results in this study indicate that GhAFP-like acts as a negative regulator in ABA signaling and is related to dormancy.

  14. Expression analysis of MYC genes from Tamarix hispida in response to different abiotic stresses.

    PubMed

    Ji, Xiaoyu; Wang, Yucheng; Liu, Guifeng

    2012-01-01

    The MYC genes are a group of transcription factors containing both bHLH and ZIP motifs that play important roles in the regulation of abscisic acid (ABA)-responsive genes. In the present study, to investigate the roles of MYC genes under NaCl, osmotic and ABA stress conditions, nine MYC genes were cloned from Tamarix hispida. Real-time reverse-transcriptase (RT)-PCR showed that all nine MYC genes were expressed in root, stem and leaf tissues, but that the levels of the transcripts of these genes in the various tissues differed notably. The MYC genes were highly induced in the roots in response to ABA, NaCl and osmotic stresses after 3 h; however, in the stem and leaf tissues, MYC genes were highly induced only when exposed to these stresses for 6 h. In addition, most of these MYC genes were highly expressed in roots in comparison with stems and leaves. Furthermore, the MYC genes were more highly induced in roots than in stem and leaf tissues, indicating that these genes may play roles in stress responses mainly in the roots rather than the stems and leaves. The results of this present study suggest that MYCs are involved in salt and osmotic stress tolerances and are controlled by the ABA signal transduction pathway.

  15. ABA induces H2O2 production in guard cells, but does not close the stomata on Vicia faba leaves developed at high air humidity.

    PubMed

    Arve, Louise E; Carvalho, Dália R A; Olsen, Jorunn E; Torre, Sissel

    2014-01-01

    Plants developed under constant high (> 85%) relative air humidity (RH) have larger stomata that are unable to close completely. One of the hypotheses for the less responsive stomata is that the plants have reduced sensitivity to abscisic acid (ABA). Both ABA and darkness are signals for stomatal closure and induce the production of the secondary messenger hydrogen peroxide (H2O2). In this study, the ability of Vicia faba plants developed in moderate or high RH to close the stomata in response to darkness, ABA and H2O2 was investigated. Moreover, the ability of the plants to produce H2O2 when treated with ABA or transferred to darkness was also assessed. Our results show that the ABA concentration in moderate RH is not increased during darkness even though the stomata are closing. This indicates that stomatal closure in V. faba during darkness is independent of ABA production. ABA induced both H2O2 production and stomatal closure in stomata formed at moderate RH. H2O2 production, as a result of treatment with ABA, was also observed in stomata formed at high RH, though the closing response was considerably smaller as compared with moderate RH. In either RH, leaf ABA concentration was not affected by darkness. Similarly to ABA treatment, darkness elicited both H2O2 production and stomatal closure following plant cultivation at moderate RH. Contrary to this, neither H2O2 production nor stomatal closure took place when stomata were formed at high RH. These results suggest that the reduced stomatal response in plants developed in continuous high RH is caused by one or more factors downstream of H2O2 in the signaling pathway toward stomatal closure.

  16. Characterization of the ABA-regulated global responses to dehydration in Arabidopsis by metabolomics.

    PubMed

    Urano, Kaoru; Maruyama, Kyonoshin; Ogata, Yoshiyuki; Morishita, Yoshihiko; Takeda, Migiwa; Sakurai, Nozomu; Suzuki, Hideyuki; Saito, Kazuki; Shibata, Daisuke; Kobayashi, Masatomo; Yamaguchi-Shinozaki, Kazuko; Shinozaki, Kazuo

    2009-03-01

    Drought is the major environmental threat to agricultural production and distribution worldwide. Adaptation by plants to dehydration stress is a complex biological process that involves global changes in gene expression and metabolite composition. Here, using one type of functional genomics analysis, metabolomics, we characterized the metabolic phenotypes of Arabidopsis wild-type and a knockout mutant of the NCED3 gene (nc3-2) under dehydration stress. NCED3 plays a role in the dehydration-inducible biosynthesis of abscisic acid (ABA), a phytohormone that is important in the dehydration-stress response in higher plants. Metabolite profiling performed using two types of mass spectrometry (MS) systems, gas chromatography/time-of-flight MS (GC/TOF-MS) and capillary electrophoresis MS (CE-MS), revealed that accumulation of amino acids depended on ABA production, but the level of the oligosaccharide raffinose was regulated by ABA independently under dehydration stress. Metabolic network analysis showed that global metabolite-metabolite correlations occurred in dehydration-increased amino acids in wild-type, and strong correlations with raffinose were reconstructed in nc3-2. An integrated metabolome and transcriptome analysis revealed ABA-dependent transcriptional regulation of the biosynthesis of the branched-chain amino acids, saccharopine, proline and polyamine. This metabolomics analysis revealed new molecular mechanisms of dynamic metabolic networks in response to dehydration stress.

  17. TaPP2C1, a Group F2 Protein Phosphatase 2C Gene, Confers Resistance to Salt Stress in Transgenic Tobacco

    PubMed Central

    Hu, Wei; Yan, Yan; Hou, Xiaowan; He, Yanzhen; Wei, Yunxie; Yang, Guangxiao; He, Guangyuan; Peng, Ming

    2015-01-01

    Group A protein phosphatases 2Cs (PP2Cs) are essential components of abscisic acid (ABA) signaling in Arabidopsis; however, the function of group F2 subfamily PP2Cs is currently less known. In this study, TaPP2C1 which belongs to group F2 was isolated and characterized from wheat. Expression of the TaPP2C1-GFP fusion protein suggested its ubiquitous localization within a cell. TaPP2C1 expression was downregulated by abscisic acid (ABA) and NaCl treatments, but upregulated by H2O2 treatment. Overexpression of TaPP2C1 in tobacco resulted in reduced ABA sensitivity and increased salt resistance of transgenic seedlings. Additionally, physiological analyses showed that improved resistance to salt stress conferred by TaPP2C1 is due to the reduced reactive oxygen species (ROS) accumulation, the improved antioxidant system, and the increased transcription of genes in the ABA-independent pathway. Finally, transgenic tobacco showed increased resistance to oxidative stress by maintaining a more effective antioxidant system. Taken together, these results demonstrated that TaPP2C1 negatively regulates ABA signaling, but positively regulates salt resistance. TaPP2C1 confers salt resistance through activating the antioxidant system and ABA-independent gene transcription process. PMID:26057628

  18. TaPP2C1, a Group F2 Protein Phosphatase 2C Gene, Confers Resistance to Salt Stress in Transgenic Tobacco.

    PubMed

    Hu, Wei; Yan, Yan; Hou, Xiaowan; He, Yanzhen; Wei, Yunxie; Yang, Guangxiao; He, Guangyuan; Peng, Ming

    2015-01-01

    Group A protein phosphatases 2Cs (PP2Cs) are essential components of abscisic acid (ABA) signaling in Arabidopsis; however, the function of group F2 subfamily PP2Cs is currently less known. In this study, TaPP2C1 which belongs to group F2 was isolated and characterized from wheat. Expression of the TaPP2C1-GFP fusion protein suggested its ubiquitous localization within a cell. TaPP2C1 expression was downregulated by abscisic acid (ABA) and NaCl treatments, but upregulated by H2O2 treatment. Overexpression of TaPP2C1 in tobacco resulted in reduced ABA sensitivity and increased salt resistance of transgenic seedlings. Additionally, physiological analyses showed that improved resistance to salt stress conferred by TaPP2C1 is due to the reduced reactive oxygen species (ROS) accumulation, the improved antioxidant system, and the increased transcription of genes in the ABA-independent pathway. Finally, transgenic tobacco showed increased resistance to oxidative stress by maintaining a more effective antioxidant system. Taken together, these results demonstrated that TaPP2C1 negatively regulates ABA signaling, but positively regulates salt resistance. TaPP2C1 confers salt resistance through activating the antioxidant system and ABA-independent gene transcription process.

  19. Abscisic Acid Represses Growth of the Arabidopsis Embryonic Axis after Germination by Enhancing Auxin Signaling[W

    PubMed Central

    Belin, Christophe; Megies, Christian; Hauserová, Eva; Lopez-Molina, Luis

    2009-01-01

    Under unfavorable environmental conditions, the stress phytohormone ABA inhibits the developmental transition from an embryo in a dry seed into a young seedling. We developed a genetic screen to isolate Arabidopsis thaliana mutants whose early seedling development is resistant to ABA. Here, we report the identification of a recessive mutation in AUXIN RESISTANT1 (AUX1), encoding a cellular auxin influx carrier. Although auxin is a major morphogenesis hormone in plants, little is known about ABA–auxin interactions during early seedling growth. We show that aux1 and pin2 mutants are insensitive to ABA-dependent repression of embryonic axis (hypocotyl and radicle) elongation. Genetic and physiological experiments show that this involves auxin transport to the embryonic axis elongation zone, where ABA enhances the activity of an auxin-responsive promoter. We propose that ABA represses embryonic axis elongation by potentiating auxin signaling in its elongation zone. This involves repression of the AUXIN INDUCIBLE (Aux/IAA) gene AXR2/IAA7, encoding a key component of ABA- and auxin-dependent responses during postgerminative growth. PMID:19666738

  20. Root ABA Accumulation Enhances Rice Seedling Drought Tolerance under Ammonium Supply: Interaction with Aquaporins

    PubMed Central

    Ding, Lei; Li, Yingrui; Wang, Ying; Gao, Limin; Wang, Min; Chaumont, François; Shen, Qirong; Guo, Shiwei

    2016-01-01

    In previous studies, we demonstrated that ammonium nutrition enhances the drought tolerance of rice seedlings compared to nitrate nutrition and contributes to a higher root water uptake ability. It remains unclear why rice seedlings maintain a higher water uptake ability when supplied with ammonium under drought stress. Here, we focused on the effects of nitrogen form and drought stress on root abscisic acid (ABA) concentration and aquaporin expression using hydroponics experiments and stimulating drought stress with 10% PEG6000. Drought stress decreased the leaf photosynthetic rate and stomatal conductivity and increased the leaf temperature of plants supplied with either ammonium or nitrate, but especially under nitrate supply. After 4 h of PEG treatment, the root protoplast water permeability and the expression of root PIP and TIP genes decreased in plants supplied with ammonium or nitrate. After 24 h of PEG treatment, the root hydraulic conductivity, the protoplast water permeability, and the expression of some aquaporin genes increased in plants supplied with ammonium compared to those under non-PEG treatment. Root ABA accumulation was induced by 24 h of PEG treatment, especially in plants supplied with ammonium. The addition of exogenous ABA decreased the expression of PIP and TIP genes under non-PEG treatment but increased the expression of some of them under PEG treatment. We concluded that drought stress induced a down-regulation of aquaporin expression, which appeared earlier than did root ABA accumulation. With continued drought stress, aquaporin expression and activity increased due to root ABA accumulation in plants supplied with ammonium. PMID:27559341

  1. Impact of ACTH Signaling on Transcriptional Regulation of Steroidogenic Genes

    PubMed Central

    Ruggiero, Carmen; Lalli, Enzo

    2016-01-01

    The trophic peptide hormone adrenocorticotropic (ACTH) stimulates steroid hormone biosynthesis evoking both a rapid, acute response and a long-term, chronic response, via the activation of cAMP/protein kinase A (PKA) signaling. The acute response is initiated by the mobilization of cholesterol from lipid stores and its delivery to the inner mitochondrial membrane, a process that is mediated by the steroidogenic acute regulatory protein. The chronic response results in the increased coordinated transcription of genes encoding steroidogenic enzymes. ACTH binding to its cognate receptor, melanocortin 2 receptor (MC2R), stimulates adenylyl cyclase, thus inducing cAMP production, PKA activation, and phosphorylation of specific nuclear factors, which bind to target promoters and facilitate coactivator protein recruitment to direct steroidogenic gene transcription. This review provides a general view of the transcriptional control exerted by the ACTH/cAMP system on the expression of genes encoding for steroidogenic enzymes in the adrenal cortex. Special emphasis will be given to the transcription factors required to mediate ACTH-dependent transcription of steroidogenic genes. PMID:27065945

  2. Carbon dioxide enrichment alleviates heat stress by improving cellular redox homeostasis through an ABA-independent process in tomato plants.

    PubMed

    Li, X; Ahammed, G J; Zhang, Y Q; Zhang, G Q; Sun, Z H; Zhou, J; Zhou, Y H; Xia, X J; Yu, J Q; Shi, K

    2015-01-01

    Plant responses to elevated CO₂ and high temperature are critically regulated through a complex network of phytohormones and redox homeostasis. However, the involvement of abscisic acid (ABA) in plant adaptation to heat stress under elevated CO₂ conditions has not been thoroughly studied. This study investigated the interactive effects of elevated CO₂ (800 μmol·mol(-1) ) and heat stress (42 °C for 24 h) on the endogenous level of ABA and the cellular redox state of two genotypes of tomato with different ABA biosynthesis capacities. Heat stress significantly decreased maximum photochemical efficiency of PSII (Fv/Fm) and leaf water potential, but also increased levels of malondialdehyde (MDA) and electrolyte leakage (EL) in both genotypes. Heat-induced damage was more severe in the ABA-deficient mutant notabilis (not) than in its parental cultivar Ailsa Craig (Ailsa), suggesting that a certain level of endogenous ABA is required to minimise the heat-induced oxidative damage to the photosynthetic apparatus. Irrespective of genotype, the enrichment of CO₂ remarkably stimulated Fv/Fm, MDA and EL in heat-stressed plants towards enhanced tolerance. In addition, elevated CO₂ significantly strengthened the antioxidant capacity of heat-stressed tomato seedlings towards a reduced cellular redox state for a prolonged period, thereby mitigating oxidative stress. However, elevated CO₂ and heat stress did not alter the endogenous level of ABA or the expression of its biosynthetic gene NCED2 in either genotype, indicating that ABA is not involved in elevated CO₂ -induced heat stress alleviation. The results of this study suggest that elevated CO₂ alleviated heat stress through efficient regulation of the cellular redox poise in an ABA-independent manner in tomato plants.

  3. Association Study of Wnt Signaling Pathway Genes in Bipolar Disorder

    PubMed Central

    Zandi, Peter P.; Belmonte, Pamela L.; Willour, Virginia L.; Goes, Fernando S.; Badner, Judith A.; Simpson, Sylvia G.; Gershon, Elliot S.; McMahon, Francis J.; DePaulo, J. Raymond; Potash, James B.

    2011-01-01

    Context The Wnt signaling pathways promote cell growth and are best known for their role in embryogenesis and cancer. Several lines of evidence suggest these pathways might also be involved in bipolar disorder (BP). Objective We tested for the association of candidate genes in the Wnt signaling pathways with disease susceptibility in a family-based BP study Design 227 tagSNPs from 34 genes were successfully genotyped. Initial results led us to focus on the gene PPARD, in which we genotyped an additional 13 SNPs for follow-up. Setting Nine academic medical centers in the United States. Participants 554 BP offspring and their parents from 317 families. Main Outcome Measures We tested for family-based association using FBAT and HBAT. Exploratory analyses testing for interactions of PPARD SNPs with clinical covariates and with other Wnt genes were conducted with GENASSOC. Results In the initial analysis, the most significantly associated SNP was rs2267665 in PPARD (nominal p=0.0003). This remained significant at p=0.05 by permutation after accounting for all SNPs tested. Additional genotyping in PPARD yielded four SNPs in one haplotype block that were significantly associated with BP at p<0.01, the most significant being rs9462082 (p=0.0001). Exploratory analyses revealed significant evidence (p<0.01) for interactions of rs9462082 with poor functioning on the Global Assessment Scale (OR = 3.36, 95% CI = 1.85–6.08), and with SNPs in WNT2B (rs3790606, OR = 2.56, 95% CI = 1.67–4.00) and WNT7A (rs4685048, OR = 1.79, 95% CI 1.23–2.63). Conclusions We found evidence for association of BP with PPARD, a gene in the Wnt signaling pathway. The consistency of this result with one from the Wellcome Trust Case-Control Consortium encourages further study. If the finding can be confirmed in additional samples, it may illuminate a new avenue for understanding the pathogenesis of severe BP and developing more effective treatments. PMID:18606951

  4. RhHB1 mediates the antagonism of gibberellins to ABA and ethylene during rose (Rosa hybrida) petal senescence.

    PubMed

    Lü, Peitao; Zhang, Changqing; Liu, Jitao; Liu, Xiaowei; Jiang, Guimei; Jiang, Xinqiang; Khan, Muhammad Ali; Wang, Liangsheng; Hong, Bo; Gao, Junping

    2014-05-01

    Rose (Rosa hybrida) is one of the most important ornamental plants worldwide; however, senescence of its petals terminates the ornamental value of the flower, resulting in major economic loss. It is known that the hormones abscisic acid (ABA) and ethylene promote petal senescence, while gibberellins (GAs) delay the process. However, the molecular mechanisms underlying the antagonistic effects amongst plant hormones during petal senescence are still unclear. Here we isolated RhHB1, a homeodomain-leucine zipper I transcription factor gene, from rose flowers. Quantitative RT-PCR and GUS reporter analyses showed that RhHB1 was strongly expressed in senescing petals, and its expression was induced by ABA or ethylene in petals. ABA or ethylene treatment clearly accelerated rose petal senescence, while application of the gibberellin GA3 delayed the process. However, silencing of RhHB1 delayed the ABA- or ethylene-mediated senescence, and resulted in higher petal anthocyanin levels and lower expression of RhSAG12. Moreover, treatment with paclobutrazol, an inhibitor of GA biosynthesis, repressed these delays. In addition, silencing of RhHB1 blocked the ABA- or ethylene-induced reduction in expression of the GA20 oxidase encoded by RhGA20ox1, a gene in the GA biosynthetic pathway. Furthermore, RhHB1 directly binds to the RhGA20ox1 promoter, and silencing of RhGA20ox1 promoted petal senescence. Eight senescence-related genes showed substantial differences in expression in petals after treatment with GA3 or paclobutrazol. These results suggest that RhHB1 mediates the antagonistic effect of GAs on ABA and ethylene during rose petal senescence, and that the promotion of petal senescence by ABA or ethylene operates through an RhHB1-RhGA20ox1 regulatory checkpoint.

  5. Gene microarray assessment of multiple genes and signal pathways involved in androgen-dependent prostate cancer becoming androgen independent.

    PubMed

    Liu, Jun-Bao; Dai, Chun-Mei; Su, Xiao-Yun; Cao, Lu; Qin, Rui; Kong, Qing-Bo

    2014-01-01

    To study the gene expression change and possible signal pathway during androgen-dependent prostate cancer (ADPC) becoming androgen-independent prostate cancer (AIPC), an LNCaP cell model of AIPC was established using flutamide in combination with androgen-free environment inducement, and differential expression genes were screened by microarray. Then the biological process, molecular function and KEGG pathway of differential expression genes are analyzed by Molecule Annotation System (MAS). By comparison of 12,207 expression genes, 347 expression genes were acquired, of which 156 were up-ragulated and 191 down-regulated. After analyzing the biological process and molecule function of differential expression genes, these genes are found to play crucial roles in cell proliferation, differntiation, cell cycle control, protein metabolism and modification and other biological process, serve as signal molecules, enzymes, peptide hormones, cytokines, cytoskeletal proteins and adhesion molecules. The analysis of KEGG show that the relevant genes of AIPC transformation participate in glutathione metabolism, cell cycle, P53 signal pathway, cytochrome P450 metabolism, Hedgehog signal pathway, MAPK signal pathway, adipocytokines signal pathway, PPAR signal pathway, TGF-β signal pathway and JAK-STAT signal pathway. In conclusion, during the process of ADPC becoming AIPC, it is not only one specific gene or pathway, but multiple genes and pathways that change. The findings above lay the foundation for study of AIPC mechanism and development of AIPC targeting drugs.

  6. Hedgehog signaling regulates gene expression in planarian glia

    PubMed Central

    Wang, Irving E; Lapan, Sylvain W; Scimone, M Lucila; Clandinin, Thomas R; Reddien, Peter W

    2016-01-01

    Hedgehog signaling is critical for vertebrate central nervous system (CNS) development, but its role in CNS biology in other organisms is poorly characterized. In the planarian Schmidtea mediterranea, hedgehog (hh) is expressed in medial cephalic ganglia neurons, suggesting a possible role in CNS maintenance or regeneration. We performed RNA sequencing of planarian brain tissue following RNAi of hh and patched (ptc), which encodes the Hh receptor. Two misregulated genes, intermediate filament-1 (if-1) and calamari (cali), were expressed in a previously unidentified non-neural CNS cell type. These cells expressed orthologs of astrocyte-associated genes involved in neurotransmitter uptake and metabolism, and extended processes enveloping regions of high synapse concentration. We propose that these cells are planarian glia. Planarian glia were distributed broadly, but only expressed if-1 and cali in the neuropil near hh+ neurons. Planarian glia and their regulation by Hedgehog signaling present a novel tractable system for dissection of glia biology. DOI: http://dx.doi.org/10.7554/eLife.16996.001 PMID:27612382

  7. Changes in gene expression and signal transduction in microgravity

    NASA Technical Reports Server (NTRS)

    Hughes-Fulford, M.

    2001-01-01

    Studies from space flights over the past three decades have demonstrated that basic physiological changes occur in humans during space flight. These changes include cephalic fluid shifts, loss of fluid and electrolytes, loss of muscle mass, space motion sickness, anemia, reduced immune response, and loss of calcium and mineralized bone. The cause of most of these manifestations is not known and until recently, the general approach was to investigate general systemic changes, not basic cellular responses to microgravity. This laboratory has recently studied gene growth and activation of normal osteoblasts (MC3T3-El) during spaceflight. Osteoblast cells were grown on glass coverslips and loaded in the Biorack plunger boxes. The osteoblasts were launched in a serum deprived state, activated in microgravity and collected in microgravity. The osteoblasts were examined for changes in gene expression and signal transduction. Approximately one day after growth activation significant changes were observed in gene expression in 0-G flight samples. Immediate early growth genes/growth factors cox-2, c-myc, bcl2, TGF beta1, bFGF and PCNA showed a significant diminished mRNA induction in microgravity FCS activated cells when compared to ground and 1-G flight controls. Cox-1 was not detected in any of the samples. There were no significant differences in the expression of reference gene mRNA between the ground, 0-G and 1-G samples. The data suggest that quiescent osteoblasts are slower to enter the cell cycle in microgravity and that the lack of gravity itself may be a significant factor in bone loss in spaceflight. Preliminary data from our STS 76 flight experiment support our hypothesis that a basic biological response occurs at the tissue, cellular, and molecular level in 0-G. Here we examine ground-based and space flown data to help us understand the mechanism of bone loss in microgravity.

  8. Prolactin receptor and signal transduction to milk protein genes

    SciTech Connect

    Djiane, J.; Daniel, N.; Bignon, C.

    1994-06-01

    After cloning of the mammary gland prolactin (PRL) receptor cDNA, a functional assay was established using co-transfection of PRL receptor cDNA together with a milk protein promoter/chloramphenicol acetyl transferase (CAT) construct in Chinese hamster ovary (CHO) cells. Different mutants of the PRL receptor were tested in this CAT assay to delimit the domains in the receptor necessary for signal transduction to milk protein genes. In CHO cells stably transfected with PRL receptor cDNA, high numbers of PRL receptor are expressed. By metabolic labeling and immunoprecipitation, expressed PRL receptor was identified as a single species of 100 kDa. Using these cells, we analyzed the effects of PRL on intracellular free Ca{sup ++} concentration. PRL stimulates Ca{sup ++} entry and induces secondary Ca{sup ++} mobilization. The entry of Ca{sup ++} is a result of an increase in K{sup +} conductance that hyperpolarizes the membranes. We have also analyzed tyrosine phosphorylation induced by PRL. In CHO cells stably transfected with PRL receptor cDNA, PRL induced a very rapid and transient tyrosine phosphorylation of a 100-kDa protein which is most probably the PRL receptor. The same finding was obtained in mammary membranes after PRL injection to lactating rabbits. Whereas tyrosine kinase inhibitors genistein and lavendustin were without effect, PRL stimulation of milk protein gene promoters was partially inhibited by 2 {mu}M herbimycin in CHO cells co-transfected with PRL receptor cDNA and the {Beta} lactoglobulin CAT construct. Taken together these observations indicate that the cytoplasmic domain of the PRL receptor interacts with one or several tyrosine kinases, which may represent early postreceptor events necessary for PRL signal transduction to milk protein genes. 14 refs., 4 figs.

  9. ABA Suppresses Root Hair Growth via the OBP4 Transcriptional Regulator1[OPEN

    PubMed Central

    Kawamura, Ayako; Schäfer, Sabine; Breuer, Christian; Shibata, Michitaro; Mitsuda, Nobutaka; Ohme-Takagi, Masaru; Matsui, Minami

    2017-01-01

    Plants modify organ growth and tune morphogenesis in response to various endogenous and environmental cues. At the cellular level, organ growth is often adjusted by alterations in cell growth, but the molecular mechanisms underlying this control remain poorly understood. In this study, we identify the DNA BINDING WITH ONE FINGER (DOF)-type transcription regulator OBF BINDING PROTEIN4 (OBP4) as a repressor of cell growth. Ectopic expression of OBP4 in Arabidopsis (Arabidopsis thaliana) inhibits cell growth, resulting in severe dwarfism and the repression of genes involved in the regulation of water transport, root hair development, and stress responses. Among the basic helix-loop-helix transcription factors known to control root hair growth, OBP4 binds the ROOT HAIR DEFECTIVE6-LIKE2 (RSL2) promoter to repress its expression. The accumulation of OBP4 proteins is detected in expanding root epidermal cells, and its expression level is increased by the application of abscisic acid (ABA) at concentrations sufficient to inhibit root hair growth. ABA-dependent induction of OBP4 is associated with the reduced expression of RSL2. Furthermore, ectopic expression of OBP4 or loss of RSL2 function results in ABA-insensitive root hair growth. Taken together, our results suggest that OBP4-mediated transcriptional repression of RSL2 contributes to the ABA-dependent inhibition of root hair growth in Arabidopsis. PMID:28167701

  10. Isohydric and anisohydric strategies of wheat genotypes under osmotic stress: biosynthesis and function of ABA in stress responses.

    PubMed

    Gallé, Ágnes; Csiszár, Jolán; Benyó, Dániel; Laskay, Gábor; Leviczky, Tünde; Erdei, László; Tari, Irma

    2013-11-01

    Changes in water potential (ψw), stomatal conductance, abscisic acid (ABA) accumulation, expression of the major genes involved in ABA biosynthesis, activities of abscisic aldehyde oxidase (AO, EC 1.2.3.1) and antioxidant enzymes were studied in two wheat cultivars with contrasting acclimation strategies subjected to medium strength osmotic stress (-0.976MPa) induced by polyethylene glycol (PEG 6000). Because the biosynthetic pathway of ABA involves multiple gene products, the aim of this study was to unravel how these genes are regulated in isohydric and anisohydric wheat genotypes. In the root tissues of the isohydric cultivar, Triticum aestivum cv. Kobomugi, osmotic stress increased the transcript levels of 9-cis-epoxycarotenoid dioxygenase (NCED) gene, controlling the rate limiting step of ABA biosynthesis. Moreover, this cultivar exhibited a higher basal activity and a higher induction of aldehyde oxidase isoenzymes (AAO2-AAO3), responsible for converting ABAldehyde to ABA. It was found that the fast activation of the ABA biosynthesis in the roots generated an enhanced ABA pool in the shoot, which brought about a faster closure of the stomata upon increasing osmotic stress and, as a result, the plants could maintain ψw in the tissues close to the control level. In contrast, the anisohydric genotype, cv. GK Öthalom, exhibited a moderate induction of ABA biosynthesis in the roots, leading to the maintenance but no increase in the concentration of ABA on the basis of tissue water content in the leaves. Due to the slower response of their stomata to water deficit, the tissues of cv. GK Öthalom have to acclimate to much more negative water potentials during increasing osmotic stress. A decreased activity of superoxide dismutase (SOD) was found in the leaves and roots of both cultivars exposed to osmotic stress, but in the roots elevated activities of catalase (CAT), peroxidase (POX), glutathione reductase (GR) and glutathione transferase (GST) were detected in

  11. Transcription factors and target genes of pre-TCR signaling.

    PubMed

    López-Rodríguez, Cristina; Aramburu, Jose; Berga-Bolaños, Rosa

    2015-06-01

    Almost 30 years ago pioneering work by the laboratories of Harald von Boehmer and Susumo Tonegawa provided the first indications that developing thymocytes could assemble a functional TCRβ chain-containing receptor complex, the pre-TCR, before TCRα expression. The discovery and study of the pre-TCR complex revealed paradigms of signaling pathways in control of cell survival and proliferation, and culminated in the recognition of the multifunctional nature of this receptor. As a receptor integrated in a dynamic developmental process, the pre-TCR must be viewed not only in the light of the biological outcomes it promotes, but also in context with those molecular processes that drive its expression in thymocytes. This review article focuses on transcription factors and target genes activated by the pre-TCR to drive its different outcomes.

  12. Genetic analysis of Physcomitrella patens identifies ABSCISIC ACID NON-RESPONSIVE, a regulator of ABA responses unique to basal land plants and required for desiccation tolerance

    SciTech Connect

    Stevenson, Sean Ross; Kamisugi, Yasuko; Trinh, Chi H.; Schmutz, Jeremy; Jenkins, Jerry W.; Grimwood, Jane; Muchero, Wellington; Tuskan, Gerald A.; Rensing, Stefan A.; Lang, Daniel; Reski, Ralf; Melkonian, Michael; Rothfels, Carl J.; Li, Fay -Wei; Larsson, Anders; Wong, Gane Ka-Shu; Edwards, Thomas A.; Cuming, Andrew C.

    2016-05-18

    The anatomically simple plants that first colonized land must have acquired molecular and biochemical adaptations to drought stress. Abscisic acid (ABA) coordinates responses leading to desiccation tolerance in all land plants. We identified ABA nonresponsive mutants in the model bryophyte Physcomitrella patens and genotyped a segregating population to map and identify the ABA NON-RESPONSIVE (ANR) gene encoding a modular protein kinase comprising an N-terminal PAS domain, a central EDR domain, and a C-terminal MAPKKK-like domain. anr mutants fail to accumulate dehydration tolerance-associated gene products in response to drought, ABA, or osmotic stress and do not acquire ABA-dependent desiccation tolerance. The crystal structure of the PAS domain, determined to 1.7-Å resolution, shows a conserved PAS-fold that dimerizes through a weak dimerization interface. Targeted mutagenesis of a conserved tryptophan residue within the PAS domain generates plants with ABA nonresponsive growth and strongly attenuated ABA-responsive gene expression, whereas deleting this domain retains a fully ABA-responsive phenotype. ANR orthologs are found in early-diverging land plant lineages and aquatic algae but are absent from more recently diverged vascular plants. Lastly, we propose that ANR genes represent an ancestral adaptation that enabled drought stress survival of the first terrestrial colonizers but were lost during land plant evolution.

  13. Clock gene evolution: seasonal timing, phylogenetic signal, or functional constraint?

    PubMed

    Krabbenhoft, Trevor J; Turner, Thomas F

    2014-01-01

    Genetic determinants of seasonal reproduction are not fully understood but may be important predictors of organism responses to climate change. We used a comparative approach to study the evolution of seasonal timing within a fish community in a natural common garden setting. We tested the hypothesis that allelic length variation in the PolyQ domain of a circadian rhythm gene, Clock1a, corresponded to interspecific differences in seasonal reproductive timing across 5 native and 1 introduced cyprinid fishes (n = 425 individuals) that co-occur in the Rio Grande, NM, USA. Most common allele lengths were longer in native species that initiated reproduction earlier (Spearman's r = -0.70, P = 0.23). Clock1a allele length exhibited strong phylogenetic signal and earlier spawners were evolutionarily derived. Aside from length variation in Clock1a, all other amino acids were identical across native species, suggesting functional constraint over evolutionary time. Interestingly, the endangered Rio Grande silvery minnow (Hybognathus amarus) exhibited less allelic variation in Clock1a and observed heterozygosity was 2- to 6-fold lower than the 5 other (nonimperiled) species. Reduced genetic variation in this functionally important gene may impede this species' capacity to respond to ongoing environmental change.

  14. Wheat ABA-insensitive mutants result in reduced grain dormancy

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This paper describes the isolation of wheat mutants in the hard red spring Scarlet resulting in reduced sensitivity to the plant hormone abscisic acid (ABA) during seed germination. ABA induces seed dormancy during embryo maturation and inhibits the germination of mature seeds. Wheat sensitivity t...

  15. Expression Patterns of ERF Genes Underlying Abiotic Stresses in Di-Haploid Populus simonii × P. nigra

    PubMed Central

    Yao, Wenjing; Jiang, Tingbo; Zhou, Boru

    2014-01-01

    176 ERF genes from Populus were identified by bioinformatics analysis, 13 of these in di-haploid Populus simonii × P. nigra were investigate by real-time RT-PCR, the results demonstrated that 13 ERF genes were highly responsive to salt stress, drought stress and ABA treatment, and all were expressed in root, stem, and leaf tissues, whereas their expression levels were markedly different in the various tissues. In roots, PthERF99, 110, 119, and 168 were primarily downregulated under drought and ABA treatment but were specifically upregulated under high salt condition. Interestingly, in poplar stems, all ERF genes showed the similar trends in expression in response to NaCl stress, drought stress, and ABA treatment, indicating that they may not play either specific or unique roles in stems in abiotic stress responses. In poplar leaves, PthERF168 was highly induced by ABA treatment, but was suppressed by high salinity and drought stresses, implying that PthERF168 participated in the ABA signaling pathway. The results of this study indicated that ERF genes could play essential but distinct roles in various plant tissues in response to different environment cues and hormonal treatment. PMID:24737991

  16. The barley HvNAC6 transcription factor affects ABA accumulation and promotes basal resistance against powdery mildew.

    PubMed

    Chen, Yan-Jun; Perera, Venura; Christiansen, Michael W; Holme, Inger B; Gregersen, Per L; Grant, Murray R; Collinge, David B; Lyngkjær, Michael F

    2013-12-01

    Barley HvNAC6 is a member of the plant-specific NAC (NAM, ATAF1,2, CUC2) transcription factor family and we have shown previously that it acts as a positive regulator of basal resistance in barley against the biotrophic pathogen Blumeria graminis f. sp. hordei (Bgh). In this study, we use a transgenic approach to constitutively silence HvNAC6 expression, using RNA interference (RNAi), to investigate the in vivo functions of HvNAC6 in basal resistance responses in barley in relation to the phytohormone ABA. The HvNAC6 RNAi plants displayed reduced HvNAC6 transcript levels and were more susceptible to Bgh than wild-type plants. Application of exogenous ABA increased basal resistance against Bgh in wild-type plants, but not in HvNAC6 RNAi plants, suggesting that ABA is a positive regulator of basal resistance which depends on HvNAC6. Silencing of HvNAC6 expression altered the light/dark rhythm of ABA levels which were, however, not influenced by Bgh inoculation. The expression of the two ABA biosynthetic genes HvNCED1 and HvNCED2 was compromised, and transcript levels of the ABA conjugating HvBG7 enzyme were elevated in the HvNAC6 RNAi lines, but this effect was not clearly associated with transgene-mediated resistance. Together, these data support a function of HvNAC6 as a regulator of ABA-mediated defence responses for maintenance of effective basal resistance against Bgh.

  17. Cryptochrome 1 regulates growth and development in Brassica through alteration in the expression of genes involved in light, phytohormone and stress signalling.

    PubMed

    Sharma, Pooja; Chatterjee, Mithu; Burman, Naini; Khurana, Jitendra P

    2014-04-01

    The blue light photoreceptors cryptochromes are ubiquitous in higher plants and are vital for regulating plant growth and development. In spite of being involved in controlling agronomically important traits like plant height and flowering time, cryptochromes have not been extensively characterized from agriculturally important crops. Here we show that overexpression of CRY1 from Brassica napus (BnCRY1), an oilseed crop, results in short-statured Brassica transgenics, likely to be less prone to wind and water lodging. The overexpression of BnCRY1 accentuates the inhibition of cell elongation in hypocotyls of transgenic seedlings. The analysis of hypocotyl growth inhibition and anthocyanin accumulation responses in BnCRY1 overexpressors substantiates that regulation of seedling photomorphogenesis by cry1 is dependent on light intensity. This study highlights that the photoactivated cry1 acts through coordinated induction and suppression of specific downstream genes involved in phytohormone synthesis or signalling, and those involved in cell wall modification, during de-etiolation of Brassica seedlings. The microarray-based transcriptome profiling also suggests that the overexpression of BnCRY1 alters abiotic/biotic stress signalling pathways; the transgenic seedlings were apparently oversensitive to abscisic acid (ABA) and mannitol.

  18. Abscisic acid signalling determines susceptibility of bundle sheath cells to photoinhibition in high light-exposed Arabidopsis leaves

    PubMed Central

    Gorecka, Magdalena; Alvarez-Fernandez, Ruben; Slattery, Katie; McAusland, Lorna; Davey, Phillip A.; Karpinski, Stanislaw; Lawson, Tracy; Mullineaux, Philip M.

    2014-01-01

    The rapid induction of the bundle sheath cell (BSC)-specific expression of ASCORBATE PEROXIDASE2 (APX2) in high light (HL)-exposed leaves of Arabidopsis thaliana is, in part, regulated by the hormone abscisic acid (ABA) produced by vascular parenchyma cells. In this study, we provide more details of the ABA signalling that regulates APX2 expression and consider its importance in the photosynthetic responses of BSCs and whole leaves. This was done using a combination of analyses of gene expression and chlorophyll a fluorescence of both leaves and individual BSCs and mesophyll cells. The regulation of APX2 expression occurs by the combination of the protein kinase SnRK2.6 (OST1):protein phosphatase 2C ABI2 and a Gα (GPA1)-regulated signalling pathway. The use of an ost1-1/gpa1-4 mutant established that these signalling pathways are distinct but interact to regulate APX2. In HL-exposed leaves, BSC chloroplasts were more susceptible to photoinhibition than those of mesophyll cells. The activity of the ABA-signalling network determined the degree of susceptibility of BSCs to photoinhibition by influencing non-photochemical quenching. By contrast, in HL-exposed whole leaves, ABA signalling did not have any major influence on their transcriptomes nor on their susceptibility to photoinhibition, except where guard cell responses were observed. PMID:24591719

  19. AtRAV and AtbZIP transcription factors positively regulate ABA responses: Overexpression in cotton enhances drought stress adaptation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Drought tolerance is an important trait being pursued by the agbiotech industry. Abscisic acid (ABA) is a stress hormone that mediates a multitude of processes in growth and development, water use efficiency, and gene expression during seed development and in response to environmental stresses. Ar...

  20. Effect of Cytokine Signaling 3 Gene Polymorphisms in Childhood Obesity

    PubMed Central

    Boyraz, Mehmet; Yeşilkaya, Ediz; Ezgü, Fatih; Bideci, Aysun; Doğan, Haldun; Ulucan, Korkut; Cinaz, Peyami

    2016-01-01

    Objective: Although polymorphisms in suppressor of cytokine signaling 3 (SOCS3) was reported to be related to obesity, Metabolic syndrome (MS), and type 2 diabetes mellitus in various adult studies, there is a lack of data in children. In this study, we examined eight reported polymorphisms of SOCS3 in obese Turkish children and adolescent with and without MS and compared the results with that of controls. Methods: One hundred and forty eight obese and 63 age- and sex-matched control subjects were enrolled in the study. Obesity classification was carried out according to body mass index. World Health Organization and National Cholesterol Education Program criteria were used for the diagnosis of MS. Genotyping procedure was carried out by polymerase chain reaction and Sanger sequencing protocol. Results: The frequency of rs2280148 polymorphism was significantly higher in obese subjects with MS than in the control group, whereas the frequency of rs8064821 polymorphism was significantly higher in obese subjects with MS than in obese children without MS. Conclusion: The significant associations of certain SOCS3 polymorphisms with obesity parameters in both MS and MS -related insulin resistance, hypertension, and fatty liver suggest that polymorphisms in this gene may play a role in the pathogenesis of MS and also that they can be potentially used as a marker for attenuated or aggressive disease. PMID:27611604

  1. Improving signal intensities for genes with low-expression on oligonucleotide microarrays

    PubMed Central

    Ramdas, Latha; Cogdell, David E; Jia, Jack Y; Taylor, Ellen E; Dunmire, Valerie R; Hu, Limei; Hamilton, Stanley R; Zhang, Wei

    2004-01-01

    Background DNA microarrays using long oligonucleotide probes are widely used to evaluate gene expression in biological samples. These oligonucleotides are pre-synthesized and sequence-optimized to represent specific genes with minimal cross-hybridization to homologous genes. Probe length and concentration are critical factors for signal sensitivity, particularly when genes with various expression levels are being tested. We evaluated the effects of oligonucleotide probe length and concentration on signal intensity measurements of the expression levels of genes in a target sample. Results Selected genes of various expression levels in a single cell line were hybridized to oligonucleotide arrays of four lengths and four concentrations of probes to determine how these critical parameters affected the intensity of the signal representing their expression. We found that oligonucleotides of longer length significantly increased the signals of genes with low-expression in the target. High-expressing gene signals were also boosted but to a lesser degree. Increasing the probe concentration, however, did not linearly increase the signal intensity for either low- or high-expressing genes. Conclusions We conclude that the longer the oligonuclotide probe the better the signal intensities of low expressing genes on oligonucleotide arrays. PMID:15196312

  2. Association and gene-gene interactions study of reelin signaling pathway related genes with autism in the Han Chinese population.

    PubMed

    Shen, Yidong; Xun, Guanglei; Guo, Hui; He, Yiqun; Ou, Jianjun; Dong, Huixi; Xia, Kun; Zhao, Jingping

    2016-04-01

    Autism is a neurodevelopmental disorder with unclear etiology. Reelin had been proposed to participate in the etiology of autism due to its important role in brain development. The goal of this study was to explore the association and gene-gene interactions of reelin signaling pathway related genes (RELN, VLDLR, LRP8, DAB1, FYN, and CDK5) with autism in Han Chinese population. Genotyping data of the six genes were obtained from a recent genome-wide association study performed in 430 autistic children who fulfilled the DSM-IV-TR criteria for autistic disorder, and 1,074 healthy controls. Single marker case-control association analysis and haplotype case-control association analysis were conducted after the data was screened. Multifactor dimensionality reduction (MDR) was applied to further test gene-gene interactions. Neither the single marker nor the haplotype association tests found any significant difference between the autistic group and the control group after permutation test of 1,000 rounds. The 4-locus MDR model (comprising rs6143734, rs1858782, rs634500, and rs1924267 which belong to RELN and DAB1) was determined to be the model with the highest cross-validation consistency (CVC) and testing balanced accuracy. The results indicate that an interaction between RELN and DAB1 may increase the risk of autism in the Han Chinese population. Furthermore, it can also be inferred that the involvement of RELN in the etiology of autism would occur through interaction with DAB1.

  3. Age-induced loss of wound-healing ability in potato tubers is partly regulated by ABA.

    PubMed

    Kumar, G N Mohan; Lulai, Edward C; Suttle, Jeffrey C; Knowles, N Richard

    2010-11-01

    Wounding of potato (Solanum tuberosum L.) tubers induces the development of a suberized closing layer and wound periderm that resists desiccation and microbial invasion. Wound-healing ability declines with tuber age (storage period). The mechanism of loss in healing capacity with age is not known; however, upregulation of superoxide production, increased ABA biosynthesis and phenylalanine ammonia lyase (PAL) activity in response to wounding are processes critical to the development of a suberized closing layer and wound periderm. Therefore, the role of ABA in modulating the age-induced loss of wound-healing ability of tubers was examined. Non-wounded older tubers had 86% less ABA (dry matter basis) than younger tubers. PAL transcript increased in younger tubers within 24 h of wounding, but transcription was delayed by 5 days in older tubers. Wound-induced PAL activity increased more rapidly in younger than older tubers. ABA treatment increased PAL expression and activity in tissue from both ages of tubers and restored the 24 h transcription time line in older tubers. Moreover, ABA treatment of wounded older tubers enhanced their resistance to water vapor loss following a 6-day wound-healing period. Wound-induced accumulation of suberin poly(phenolic(s)) (SPP) and suberin poly(aliphatic(s)) (SPA) was measurably slower in older versus younger tubers. ABA treatment hastened SPP accumulation in older tubers to match that in younger tubers, but only enhanced SPA accumulations over the initial 4 days of healing. Age-induced loss of wound-healing ability is thus partly due to reduced ability to accumulate ABA and modulate the production of SPP through PAL in response to wounding and to dysfunction in the downstream signaling events that couple SPA biosynthesis and/or deposition to ABA. ABA treatment partly restored the healing ability of older tubers by enhancing the accumulation of SPP without restoring wound-induced superoxide forming ability to the level of younger

  4. Graphene oxide modulates root growth of Brassica napus L. and regulates ABA and IAA concentration.

    PubMed

    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.

  5. Arabidopsis cold shock domain protein 2 influences ABA accumulation in seed and negatively regulates germination.

    PubMed

    Sasaki, Kentaro; Kim, Myung-Hee; Kanno, Yuri; Seo, Mitsunori; Kamiya, Yuji; Imai, Ryozo

    2015-01-02

    The cold shock domain (CSD) is the most conserved nucleic acid binding domain and is distributed from bacteria to animals and plants. CSD proteins are RNA chaperones that destabilize RNA secondary structures to regulate stress tolerance and development. AtCSP2 is one of the four CSD proteins in Arabidopsis and is up-regulated in response to cold. Since AtCSP2 negatively regulates freezing tolerance, it was proposed to be a modulator of freezing tolerance during cold acclimation. Here, we examined the function of AtCSP2 in seed germination. We found that AtCSP2-overexpressing lines demonstrated retarded germination as compared with the wild type, with or without stress treatments. The ABA levels in AtCSP2-overexpressing seeds were higher than those in the wild type. In addition, overexpression of AtCSP2 reduced the expression of an ABA catabolic gene (CYP707A2) and gibberellin biosynthesis genes (GA20ox and GA3ox). These results suggest that AtCSP2 negatively regulates seed germination by controlling ABA and GA levels.

  6. Role of T-box gene tbx-2 for anterior foregut muscle development in C. elegans

    PubMed Central

    Smith, Pliny A.; Mango, Susan E.

    2007-01-01

    SUMMARY During organogenesis, pluripotent precursor cells acquire a defined identity such as muscle or nerve. The transition from naïve precursor towards the differentiated state is characterized by sequential waves of gene expression that are determined by regulatory transcription factors. A key question is how transcriptional circuitry dictates the succession of events that accompanies developmental competence, cell fate specification and differentiation. To address this question, we have examined how anterior muscles are established within the C. elegans foregut (pharynx). We find that the T-box transcription factor tbx-2 is essential to form anterior pharyngeal muscles from the ABa blastomere. In the absence of tbx-2 function, ABa-derived cells initiate development normally: they receive glp-1/Notch signaling cues, activate the T-box gene TBX-38 and express the organ selector gene PHA-4/FoxA. However, these cells subsequently arrest development, extinguish PHA-4 and fail to activate PHA-4 target genes. tbx-2 mutant cells do not undergo apoptosis and there is no evidence for adoption of an alternative fate. TBX-2 is expressed in ABa descendants and depends on activation by pha-4 and repression by glp-1/Notch signaling. Our analysis suggests that a positive feedback loop between tbx-2 and pha-4 is required for ABa-derived precursors to commit to pharyngeal muscle fate. PMID:17005176

  7. The miR165/166 Mediated Regulatory Module Plays Critical Roles in ABA Homeostasis and Response in Arabidopsis thaliana

    PubMed Central

    Zhou, Jianping; Yang, Yu; Tang, Guiliang; Bressan, Ray A.

    2016-01-01

    The function of miR165/166 in plant growth and development has been extensively studied, however, its roles in abiotic stress responses remain largely unknown. Here, we report that reduction in the expression of miR165/166 conferred a drought and cold resistance phenotype and hypersensitivity to ABA during seed germination and post-germination seedling development. We further show that the ABA hypersensitive phenotype is associated with a changed transcript abundance of ABA-responsive genes and a higher expression level of ABI4, which can be directly regulated by a miR165/166 target. Additionally, we found that reduction in miR165/166 expression leads to elevated ABA levels, which occurs at least partially through the increased expression of BG1, a gene that is directly regulated by a miR165/166 target. Taken together, our results uncover a novel role for miR165/166 in the regulation of ABA and abiotic stress responses and control of ABA homeostasis. PMID:27812104

  8. Products of lipid, protein and RNA oxidation as signals and regulators of gene expression in plants

    PubMed Central

    Chmielowska-Bąk, Jagna; Izbiańska, Karolina; Deckert, Joanna

    2015-01-01

    Reactive oxygen species (ROS) are engaged in several processes essential for normal cell functioning, such as differentiation, anti-microbial defense, stimulus sensing and signaling. Interestingly, recent studies imply that cellular signal transduction and gene regulation are mediated not only directly by ROS but also by the molecules derived from ROS-mediated oxidation. Lipid peroxidation leads to non-enzymatic formation of oxylipins. These molecules were shown to modulate expression of signaling associated genes including genes encoding phosphatases, kinases and transcription factors. Oxidized peptides derived from protein oxidation might be engaged in organelle-specific ROS signaling. In turn, oxidation of particular mRNAs leads to decrease in the level of encoded proteins and thus, contributes to the post-transcriptional regulation of gene expression. Present mini review summarizes latest findings concerning involvement of products of lipid, protein and RNA oxidation in signal transduction and gene regulation. PMID:26082792

  9. Mapping toll-like receptor signaling pathway genes of Zhikong scallop ( Chlamys farreri) with FISH

    NASA Astrophysics Data System (ADS)

    Zhao, Bosong; Zhao, Liang; Liao, Huan; Cheng, Jie; Lian, Shanshan; Li, Xuan; Huang, Xiaoting; Bao, Zhenmin

    2015-12-01

    Toll-like receptor (TLR) signaling pathway plays a pivotal role in the innate immune system. Studies on TLR signaling pathway genes in Zhikong scallop ( Chlamys farreri) have mainly focused on sequence analysis and expression profiling, no research has been carried out on their localization. The chromosomal position of TLR signaling pathway genes can be valuable for assemblying scallop genome and analysizing gene regulatory networks. In the present study, five key TLR signaling pathway genes ( CfTLR, CfMyd88, CfTRAF6, CfNFκB, and CfIκB) containing bacterial artificial chromosomes (BACs) were isolated and physically mapped through fluorescence in situ hybridization on five non-homologous chromosome pairs, showing a similar distribution to another five model species. The isolation and mapping of these key immune genes of C. farreri will aid to the research on innate immunity, assignment of interested genes to chromosomes, and integration of physical, linkage and cytogenetic maps of this species.

  10. Dynamic signal processing by ribozyme-mediated RNA circuits to control gene expression.

    PubMed

    Shen, Shensi; Rodrigo, Guillermo; Prakash, Satya; Majer, Eszter; Landrain, Thomas E; Kirov, Boris; Daròs, José-Antonio; Jaramillo, Alfonso

    2015-05-26

    Organisms have different circuitries that allow converting signal molecule levels to changes in gene expression. An important challenge in synthetic biology involves the de novo design of RNA modules enabling dynamic signal processing in live cells. This requires a scalable methodology for sensing, transmission, and actuation, which could be assembled into larger signaling networks. Here, we present a biochemical strategy to design RNA-mediated signal transduction cascades able to sense small molecules and small RNAs. We design switchable functional RNA domains by using strand-displacement techniques. We experimentally characterize the molecular mechanism underlying our synthetic RNA signaling cascades, show the ability to regulate gene expression with transduced RNA signals, and describe the signal processing response of our systems to periodic forcing in single live cells. The engineered systems integrate RNA-RNA interaction with available ribozyme and aptamer elements, providing new ways to engineer arbitrary complex gene circuits.

  11. Dynamic signal processing by ribozyme-mediated RNA circuits to control gene expression

    PubMed Central

    Shen, Shensi; Rodrigo, Guillermo; Prakash, Satya; Majer, Eszter; Landrain, Thomas E.; Kirov, Boris; Daròs, José-Antonio; Jaramillo, Alfonso

    2015-01-01

    Organisms have different circuitries that allow converting signal molecule levels to changes in gene expression. An important challenge in synthetic biology involves the de novo design of RNA modules enabling dynamic signal processing in live cells. This requires a scalable methodology for sensing, transmission, and actuation, which could be assembled into larger signaling networks. Here, we present a biochemical strategy to design RNA-mediated signal transduction cascades able to sense small molecules and small RNAs. We design switchable functional RNA domains by using strand-displacement techniques. We experimentally characterize the molecular mechanism underlying our synthetic RNA signaling cascades, show the ability to regulate gene expression with transduced RNA signals, and describe the signal processing response of our systems to periodic forcing in single live cells. The engineered systems integrate RNA–RNA interaction with available ribozyme and aptamer elements, providing new ways to engineer arbitrary complex gene circuits. PMID:25916845

  12. EGF receptor signaling triggers recruitment of Drosophila sense organ precursors by stimulating proneural gene autoregulation.

    PubMed

    zur Lage, Petra I; Powell, Lynn M; Prentice, David R A; McLaughlin, Paul; Jarman, Andrew P

    2004-11-01

    In Drosophila, commitment of a cell to a sense organ precursor (SOP) fate requires bHLH proneural transcription factor upregulation, a process that depends in most cases on the interplay of proneural gene autoregulation and inhibitory Notch signaling. A subset of SOPs are selected by a recruitment pathway involving EGFR signaling to ectodermal cells expressing the proneural gene atonal. We show that EGFR signaling drives recruitment by directly facilitating atonal autoregulation. Pointed, the transcription factor that mediates EGFR signaling, and Atonal protein itself bind cooperatively to adjacent conserved binding sites in an atonal enhancer. Recruitment is therefore contingent on the combined presence of Atonal protein (providing competence) and EGFR signaling (triggering recruitment). Thus, autoregulation is the nodal control point targeted by signaling. This exemplifies a simple and general mechanism for regulating the transition from competence to cell fate commitment whereby a cell signal directly targets the autoregulation of a selector gene.

  13. Conserved gene structures and expression signals in methanogenic archaebacteria.

    PubMed

    Allmansberger, R; Bokranz, M; Kröckel, L; Schallenberg, J; Klein, A

    1989-01-01

    A comparative analysis of cotranscribed gene clusters comprising the structural genes mcrA, mcrB, mcrC, mcrD, and mcrG was carried out in three species of methanogens. mcrA, mcrB, and mcrG are the structural genes for the three subunits of methyl coenzyme M reductase, while the two other genes encode polypeptides of unknown functions. The degree of conservation of the mcr gene products among different species of methanogens varies. No correlation was found between the conservation of the G+C contents of the homologous genes and of the amino acid sequences of their products among the different bacteria. The comparison of RNA polymerase core subunit genes of Methanobacterium thermoautotrophicum as evolutionary markers with their equivalents in Escherichia coli, Saccharomyces cerevisiae, and Drosophila melanogaster showed that homologous polypeptide domains are encoded by different numbers of genes suggesting gene fusion of adjacent genes in the course of evolution. The archaebacterial subunits exhibit much stronger homology with their eukaryotic than with their eubacterial equivalents on the polypeptide sequence level. All the analyzed genes are preceded by ribosome binding sites of eubacterial type. In addition to known putative promoter sequences, conserved structural elements of the DNA were detected surrounding the transcription initiation sites of the mcr genes.

  14. The ABA-mediated switch between submersed and emersed life-styles in aquatic macrophytes.

    PubMed

    Wanke, Dierk

    2011-07-01

    Hydrophytes comprise aquatic macrophytes from various taxa that are able to sustain and to complete their lifecycle in a flooded environment. Their ancestors, however, underwent adaptive processes to withstand drought on land and became partially or completely independent of water for sexual reproduction. Interestingly, the step backwards into the high-density aquatic medium happened independently several times in numerous plant taxa. For flowering plants, this submersed life-style is especially difficult as they need to erect their floral organs above the water surface to be pollinated. Moreover, fresh-water plants evolved the adaptive mechanism of heterophylly, which enabled them to switch between a submersed and an emersed leaf morphology. The plant hormone abscisic acid (ABA) is a key factor of heterophylly induction in aquatic plants and is a major switch between a submersed and emersed life. The mechanisms of ABA signal perception and transduction appear to be conserved throughout the evolution of basal plants to angiosperms and from terrestrial to aquatic plants. This review summarizes the interplay of environmental factors that act through ABA to orchestrate adaptation of plants to their aquatic environment.

  15. Powdery Mildew Resistance Conferred by Loss of the ENHANCED DISEASE RESISTANCE1 Protein Kinase Is Suppressed by a Missense Mutation in KEEP ON GOING, a Regulator of Abscisic Acid Signaling1[W][OA

    PubMed Central

    Wawrzynska, Anna; Christiansen, Katy M.; Lan, Yinan; Rodibaugh, Natalie L.; Innes, Roger W.

    2008-01-01

    Loss-of-function mutations in the Arabidopsis (Arabidopsis thaliana) ENHANCED DISEASE RESISTANCE1 (EDR1) gene confer enhanced resistance to infection by powdery mildew (Golovinomyces cichoracearum). EDR1 encodes a protein kinase, but its substrates and the pathways regulated by EDR1 are unknown. To identify components of the EDR1 signal transduction pathway(s), we conducted a forward genetic screen for mutations that suppressed edr1-mediated disease resistance. Genetic mapping and cloning of one of these suppressor mutations revealed a recessive missense mutation in the KEEP ON GOING gene (KEG; At5g13530), which we designated keg-4. KEG encodes a multidomain protein that includes a RING E3 ligase domain, a kinase domain, ankyrin repeats, and HERC2-like repeats. The KEG protein has previously been shown to have ubiquitin ligase activity and to negatively regulate protein levels of the transcription factor ABCISIC ACID INSENSITIVE5. KEG mRNA levels were found to be 3-fold higher in edr1 mutant plants compared to wild type. Loss-of-function mutations in KEG are seedling lethal and are hypersensitive to glucose and abscisic acid (ABA). The keg-4 mutation, in contrast, conferred resistance to 6% glucose and suppressed edr1-mediated hypersensitivity to ABA, suggesting that the keg-4 mutation suppresses ABA signaling by altering KEG function. Several ABA-responsive genes were found to be further up-regulated in the edr1 mutant following ABA treatment, and this up-regulation was suppressed by the keg-4 mutation. We conclude that edr1-mediated resistance to powdery mildew is mediated, in part, by enhanced ABA signaling. PMID:18815384

  16. Powdery mildew resistance conferred by loss of the ENHANCED DISEASE RESISTANCE1 protein kinase is suppressed by a missense mutation in KEEP ON GOING, a regulator of abscisic acid signaling.

    PubMed

    Wawrzynska, Anna; Christiansen, Katy M; Lan, Yinan; Rodibaugh, Natalie L; Innes, Roger W

    2008-11-01

    Loss-of-function mutations in the Arabidopsis (Arabidopsis thaliana) ENHANCED DISEASE RESISTANCE1 (EDR1) gene confer enhanced resistance to infection by powdery mildew (Golovinomyces cichoracearum). EDR1 encodes a protein kinase, but its substrates and the pathways regulated by EDR1 are unknown. To identify components of the EDR1 signal transduction pathway(s), we conducted a forward genetic screen for mutations that suppressed edr1-mediated disease resistance. Genetic mapping and cloning of one of these suppressor mutations revealed a recessive missense mutation in the KEEP ON GOING gene (KEG; At5g13530), which we designated keg-4. KEG encodes a multidomain protein that includes a RING E3 ligase domain, a kinase domain, ankyrin repeats, and HERC2-like repeats. The KEG protein has previously been shown to have ubiquitin ligase activity and to negatively regulate protein levels of the transcription factor ABCISIC ACID INSENSITIVE5. KEG mRNA levels were found to be 3-fold higher in edr1 mutant plants compared to wild type. Loss-of-function mutations in KEG are seedling lethal and are hypersensitive to glucose and abscisic acid (ABA). The keg-4 mutation, in contrast, conferred resistance to 6% glucose and suppressed edr1-mediated hypersensitivity to ABA, suggesting that the keg-4 mutation suppresses ABA signaling by altering KEG function. Several ABA-responsive genes were found to be further up-regulated in the edr1 mutant following ABA treatment, and this up-regulation was suppressed by the keg-4 mutation. We conclude that edr1-mediated resistance to powdery mildew is mediated, in part, by enhanced ABA signaling.

  17. Evolution of Abscisic Acid Synthesis and Signaling Mechanisms

    PubMed Central

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

    2011-01-01

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

  18. Evolution of abscisic acid synthesis and signaling mechanisms.

    PubMed

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

    2011-05-10

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

  19. abaA controls phialide differentiation in Aspergillus nidulans.

    PubMed Central

    Sewall, T C; Mims, C W; Timberlake, W E

    1990-01-01

    Aspergillus nidulans is an ascomycetous fungus that reproduces asexually by forming multicellular conidiophores and uninucleate spores called conidia. Loss of function mutations in the abacus A (abaA) regulatory locus result in formation of aberrant conidiophores that fail to produce conidia. Wild-type conidiophores form two tiers of sterigmata. The first tier, metulae, divide to produce the second tier, phialides. Phialides are sporogenous cells that produce conidia through a specialized apical budding process. We have examined conidiophore development in an abaA- strain at the ultrastructural level. The results showed that in the mutant metulae produce supernumerary tiers of cells with metula-like, rather than phialide-like, properties. Temperature shift experiments with an abaA14ts strain demonstrated that abaA+ function induced phialide formation by the aberrant abacus cells and was continuously required for maintenance of phialide function. In the absence of abaA+ activity, metulae simply proliferated and later developmental steps never occurred. We conclude that abaA+ directs the differentiation of phialides and is continuously required for maintenance of their function. PMID:2152124

  20. ASG2 is a farnesylated DWD protein that acts as ABA negative regulator in Arabidopsis.

    PubMed

    Dutilleul, Christelle; Ribeiro, Iliana; Blanc, Nathalie; Nezames, Cynthia D; Deng, Xing Wang; Zglobicki, Piotr; Palacio Barrera, Ana María; Atehortùa, Lucia; Courtois, Martine; Labas, Valérie; Giglioli-Guivarc'h, Nathalie; Ducos, Eric

    2016-01-01

    The tagging-via-substrate approach designed for the capture of mammal prenylated proteins was adapted to Arabidopsis cell culture. In this way, proteins are in vivo tagged with an azide-modified farnesyl moiety and captured thanks to biotin alkyne Click-iT® chemistry with further streptavidin-affinity chromatography. Mass spectrometry analyses identified four small GTPases and ASG2 (ALTERED SEED GERMINATION 2), a protein previously associated to the seed germination gene network. ASG2 is a conserved protein in plants and displays a unique feature that associates WD40 domains and tetratricopeptide repeats. Additionally, we show that ASG2 has a C-terminal CaaX-box that is farnesylated in vitro. Protoplast transfections using CaaX prenyltransferase mutants show that farnesylation provokes ASG2 nucleus exclusion. Moreover, ASG2 interacts with DDB1 (DAMAGE DNA BINDING protein 1), and the subcellular localization of this complex depends on ASG2 farnesylation status. Finally, germination and root elongation experiments reveal that asg2 and the farnesyltransferase mutant era1 (ENHANCED RESPONSE TO ABSCISIC ACID (ABA) 1) behave in similar manners when exposed to ABA or salt stress. To our knowledge, ASG2 is the first farnesylated DWD (DDB1 binding WD40) protein related to ABA response in Arabidopsis that may be linked to era1 phenotypes.

  1. Identification of mechanosensitive genes during skeletal development: alteration of genes associated with cytoskeletal rearrangement and cell signalling pathways

    PubMed Central

    2014-01-01

    Background Mechanical stimulation is necessary for regulating correct formation of the skeleton. Here we test the hypothesis that mechanical stimulation of the embryonic skeletal system impacts expression levels of genes implicated in developmentally important signalling pathways in a genome wide approach. We use a mutant mouse model with altered mechanical stimulation due to the absence of limb skeletal muscle (Splotch-delayed) where muscle-less embryos show specific defects in skeletal elements including delayed ossification, changes in the size and shape of cartilage rudiments and joint fusion. We used Microarray and RNA sequencing analysis tools to identify differentially expressed genes between muscle-less and control embryonic (TS23) humerus tissue. Results We found that 680 independent genes were down-regulated and 452 genes up-regulated in humeri from muscle-less Spd embryos compared to littermate controls (at least 2-fold; corrected p-value ≤0.05). We analysed the resulting differentially expressed gene sets using Gene Ontology annotations to identify significant enrichment of genes associated with particular biological processes, showing that removal of mechanical stimuli from muscle contractions affected genes associated with development and differentiation, cytoskeletal architecture and cell signalling. Among cell signalling pathways, the most strongly disturbed was Wnt signalling, with 34 genes including 19 pathway target genes affected. Spatial gene expression analysis showed that both a Wnt ligand encoding gene (Wnt4) and a pathway antagonist (Sfrp2) are up-regulated specifically in the developing joint line, while the expression of a Wnt target gene, Cd44, is no longer detectable in muscle-less embryos. The identification of 84 genes associated with the cytoskeleton that are down-regulated in the absence of muscle indicates a number of candidate genes that are both mechanoresponsive and potentially involved in mechanotransduction, converting a

  2. Gene expression analysis reveals that Delta/Notch signalling is not involved in onychophoran segmentation.

    PubMed

    Janssen, Ralf; Budd, Graham E

    2016-03-01

    Delta/Notch (Dl/N) signalling is involved in the gene regulatory network underlying the segmentation process in vertebrates and possibly also in annelids and arthropods, leading to the hypothesis that segmentation may have evolved in the last common ancestor of bilaterian animals. Because of seemingly contradicting results within the well-studied arthropods, however, the role and origin of Dl/N signalling in segmentation generally is still unclear. In this study, we investigate core components of Dl/N signalling by means of gene expression analysis in the onychophoran Euperipatoides kanangrensis, a close relative to the arthropods. We find that neither Delta or Notch nor any other investigated components of its signalling pathway are likely to be involved in segment addition in onychophorans. We instead suggest that Dl/N signalling may be involved in posterior elongation, another conserved function of these genes. We suggest further that the posterior elongation network, rather than classic Dl/N signalling, may be in the control of the highly conserved segment polarity gene network and the lower-level pair-rule gene network in onychophorans. Consequently, we believe that the pair-rule gene network and its interaction with Dl/N signalling may have evolved within the arthropod lineage and that Dl/N signalling has thus likely been recruited independently for segment addition in different phyla.

  3. Stress Tolerance and Glucose Insensitive Phenotypes in Arabidopsis Overexpressing the CpMYB10 Transcription Factor Gene1

    PubMed Central

    Villalobos, Miguel Angel; Bartels, Dorothea; Iturriaga, Gabriel

    2004-01-01

    The resurrection plant Craterostigma plantagineum has the ability to survive complete dehydration. In an attempt to further understand desiccation tolerance in this plant, the CpMYB10 transcription factor gene was functionally characterized. CpMYB10 is rapidly induced by dehydration and abscisic acid (ABA) treatments in leaves and roots, but no expression was detected in fully hydrated tissues. Electrophoretic mobility shift assay experiments showed binding of rCpMYB10 to specific mybRE elements within the LEA Cp11-24 and CpMYB10 promoters. Localization of CpMYB10 transcript by in situ reverse transcription-PCR reactions showed expression in vascular tissues, parenchyma, and epidermis both in leaves and roots in response to ABA. Transgenic Arabidopsis plants transformed with CpMYB10 promoter fused to GUS gene showed reporter expression under ABA and stress conditions in several organs. Overexpression of CpMYB10 cDNA in Arabidopsis led to desiccation and salt tolerance of transgenics lines. Interestingly, it was found that plants overexpressing CpMYB10 exhibited Glc-insensitive and ABA hypersensitive phenotypes. Therefore, our results indicate that CpMYB10 in Arabidopsis is mediating stress tolerance and altering ABA and Glc signaling responses. PMID:15122027

  4. Genes that integrate multiple adipogenic signaling pathways in human mesenchymal stem cells.

    PubMed

    Ito, Tomoya; Tsuruta, So; Tomita, Koki; Kikuchi, Kunio; Yokoi, Takahide; Aizawa, Yasunori

    2011-06-17

    Adipogenesis is a well-characterized cell differentiation process. A large body of evidence has revealed the core transcription factors and signaling pathways that govern adipogenesis, but cross-talks between these cellular signals and its functional consequences have not been thoroughly investigated. We, therefore, sought to identify genes that are regulated by multiple signaling pathways during adipogenesis of human mesenchymal stem cells. Focusing on the early stage of adipogenesis, microarray analysis and quantitative RT-PCR identified 12 genes whose transcription levels were dramatically affected by the complete adipogenic induction cocktail but not by the cocktail's individual components. Expression kinetics of these genes indicate diverse mechanisms of transcriptional regulation during adipogenesis. Functional relationships between these genes and adipogenic differentiation were frequently unknown. This study thus provided novel adipogenic gene candidates that likely mediate communications among multiple signaling pathways within human mesenchymal stem cells.

  5. Multiple impacts of the plant growth-promoting rhizobacterium Variovorax paradoxus 5C-2 on nutrient and ABA relations of Pisum sativum

    PubMed Central

    Dodd, Ian C.

    2012-01-01

    Resolving the physiological mechanisms by which rhizobacteria enhance plant growth is difficult, since many such bacteria contain multiple plant growth-promoting properties. To understand further how the 1-aminocyclopropane-1-carboxylate (ACC) deaminase (ACCd)-containing rhizobacterium Variovorax paradoxus 5C-2 affects plant growth, the flows and partitioning of mineral nutrients and abscisic acid (ABA) and ABA metabolism were studied in pea (Pisum sativum) plants following rhizosphere bacterial inoculation. Although root architecture was not affected, inoculation increased root and shoot biomass, and stomatal conductance, by 20, 15, and 24%, respectively, and increased N, P, K, Ca, and Mg uptake by 16, 81, 50, 46, and 58%, respectively. P deposition in inoculated plant roots was 4.9 times higher than that in uninoculated controls. Rhizobacterial inoculation increased root to shoot xylem flows and shoot to root phloem flows of K by 1.8- and 2.1-fold, respectively. In control plants, major sinks for K deposition were the roots and upper shoot (43% and 49% of total uptake, respectively), while rhizobacterial inoculation increased K distribution to the lower shoot at the expense of other compartments (xylem, phloem, and upper shoot). Despite being unable to metabolize ABA in vitro, V. paradoxus 5C-2 decreased root ABA concentrations and accumulation by 40–60%. Although inoculation decreased xylem ABA flows, phloem ABA flows increased. Whether bacterial ACCd attenuates root to shoot ABA signalling requires further investigation, since ABA is critical to maintain growth of droughted plants, and ACCd-containing organisms have been advocated as a means of minimizing growth inhibition of plants in drying soil. PMID:23136167

  6. Negative feedback regulation of ABA biosynthesis in peanut (Arachis hypogaea): a transcription factor complex inhibits AhNCED1 expression during water stress

    PubMed Central

    Liu, Shuai; Li, Meijuan; Su, Liangchen; Ge, Kui; Li, Limei; Li, Xiaoyun; Liu, Xu; Li, Ling

    2016-01-01

    Abscisic acid (ABA), a key plant stress-signaling hormone, is produced in response to drought and counteracts the effects of this stress. The accumulation of ABA is controlled by the enzyme 9-cis-epoxycarotenoid dioxygenase (NCED). In Arabidopsis, NCED3 is regulated by a positive feedback mechanism by ABA. In this study in peanut (Arachis hypogaea), we demonstrate that ABA biosynthesis is also controlled by negative feedback regulation, mediated by the inhibitory effect on AhNCED1 transcription of a protein complex between transcription factors AhNAC2 and AhAREB1. AhNCED1 was significantly down-regulated after PEG treatment for 10 h, at which time ABA content reached a peak. A ChIP-qPCR assay confirmed AhAREB1 and AhNAC2 binding to the AhNCED1 promoter in response to ABA. Moreover, the interaction between AhAREB1 and AhNAC2, and a transient expression assay showed that the protein complex could negatively regulate the expression of AhNCED1. The results also demonstrated that AhAREB1 was the key factor in AhNCED1 feedback regulation, while AhNAC2 played a subsidiary role. ABA reduced the rate of AhAREB1 degradation and enhanced both the synthesis and degradation rate of the AhNAC2 protein. In summary, the AhAREB1/AhNAC2 protein complex functions as a negative feedback regulator of drought-induced ABA biosynthesis in peanut. PMID:27892506

  7. Multiple impacts of the plant growth-promoting rhizobacterium Variovorax paradoxus 5C-2 on nutrient and ABA relations of Pisum sativum.

    PubMed

    Jiang, Fan; Chen, Lin; Belimov, Andrey A; Shaposhnikov, Alexander I; Gong, Fan; Meng, Xu; Hartung, Wolfram; Jeschke, Dieter W; Davies, William J; Dodd, Ian C

    2012-11-01

    Resolving the physiological mechanisms by which rhizobacteria enhance plant growth is difficult, since many such bacteria contain multiple plant growth-promoting properties. To understand further how the 1-aminocyclopropane-1-carboxylate (ACC) deaminase (ACCd)-containing rhizobacterium Variovorax paradoxus 5C-2 affects plant growth, the flows and partitioning of mineral nutrients and abscisic acid (ABA) and ABA metabolism were studied in pea (Pisum sativum) plants following rhizosphere bacterial inoculation. Although root architecture was not affected, inoculation increased root and shoot biomass, and stomatal conductance, by 20, 15, and 24%, respectively, and increased N, P, K, Ca, and Mg uptake by 16, 81, 50, 46, and 58%, respectively. P deposition in inoculated plant roots was 4.9 times higher than that in uninoculated controls. Rhizobacterial inoculation increased root to shoot xylem flows and shoot to root phloem flows of K by 1.8- and 2.1-fold, respectively. In control plants, major sinks for K deposition were the roots and upper shoot (43% and 49% of total uptake, respectively), while rhizobacterial inoculation increased K distribution to the lower shoot at the expense of other compartments (xylem, phloem, and upper shoot). Despite being unable to metabolize ABA in vitro, V. paradoxus 5C-2 decreased root ABA concentrations and accumulation by 40-60%. Although inoculation decreased xylem ABA flows, phloem ABA flows increased. Whether bacterial ACCd attenuates root to shoot ABA signalling requires further investigation, since ABA is critical to maintain growth of droughted plants, and ACCd-containing organisms have been advocated as a means of minimizing growth inhibition of plants in drying soil.

  8. Identification of the genes regulated by Wnt-4, a critical signal for commitment of the ovary.

    PubMed

    Naillat, Florence; Yan, Wenying; Karjalainen, Riikka; Liakhovitskaia, Anna; Samoylenko, Anatoly; Xu, Qi; Sun, Zhandong; Shen, Bairong; Medvinsky, Alexander; Quaggin, Susan; Vainio, Seppo J

    2015-03-15

    The indifferent mammalian embryonic gonad generates an ovary or testis, but the factors involved are still poorly known. The Wnt-4 signal represents one critical female determinant, since its absence leads to partial female-to-male sex reversal in mouse, but its signalling is as well implicated in the testis development. We used the Wnt-4 deficient mouse as a model to identify candidate gonadogenesis genes, and found that the Notum, Phlda2, Runx-1 and Msx1 genes are typical of the wild-type ovary and the Osr2, Dach2, Pitx2 and Tacr3 genes of the testis. Strikingly, the expression of these latter genes becomes reversed in the Wnt-4 knock-out ovary, suggesting a role in ovarian development. We identified the transcription factor Runx-1 as a Wnt-4 signalling target gene, since it is expressed in the ovary and is reduced upon Wnt-4 knock-out. Consistent with this, introduction of the Wnt-4 signal into early ovary cells ex vivo induces Runx-1 expression, while conversely Wnt-4 expression is down-regulated in the absence of Runx-1. We conclude that the Runx-1 gene can be a Wnt-4 signalling target, and that Runx-1 and Wnt-4 are mutually interdependent in their expression. The changes in gene expression due to the absence of Wnt-4 in gonads reflect the sexually dimorphic role of this signal and its complex gene network in mammalian gonad development.

  9. Global identification of genes regulated by estrogen signaling and demethylation in MCF-7 breast cancer cells

    SciTech Connect

    Putnik, Milica; Zhao, Chunyan; Gustafsson, Jan-Ake; Dahlman-Wright, Karin

    2012-09-14

    Highlights: Black-Right-Pointing-Pointer Estrogen signaling and demethylation can both control gene expression in breast cancers. Black-Right-Pointing-Pointer Cross-talk between these mechanisms is investigated in human MCF-7 breast cancer cells. Black-Right-Pointing-Pointer 137 genes are influenced by both 17{beta}-estradiol and demethylating agent 5-aza-2 Prime -deoxycytidine. Black-Right-Pointing-Pointer A set of genes is identified as targets of both estrogen signaling and demethylation. Black-Right-Pointing-Pointer There is no direct molecular interplay of mediators of estrogen and epigenetic signaling. -- Abstract: Estrogen signaling and epigenetic modifications, in particular DNA methylation, are involved in regulation of gene expression in breast cancers. Here we investigated a potential regulatory cross-talk between these two pathways by identifying their common target genes and exploring underlying molecular mechanisms in human MCF-7 breast cancer cells. Gene expression profiling revealed that the expression of approximately 140 genes was influenced by both 17{beta}-estradiol (E2) and a demethylating agent 5-aza-2 Prime -deoxycytidine (DAC). Gene ontology (GO) analysis suggests that these genes are involved in intracellular signaling cascades, regulation of cell proliferation and apoptosis. Based on previously reported association with breast cancer, estrogen signaling and/or DNA methylation, CpG island prediction and GO analysis, we selected six genes (BTG3, FHL2, PMAIP1, BTG2, CDKN1A and TGFB2) for further analysis. Tamoxifen reverses the effect of E2 on the expression of all selected genes, suggesting that they are direct targets of estrogen receptor. Furthermore, DAC treatment reactivates the expression of all selected genes in a dose-dependent manner. Promoter CpG island methylation status analysis revealed that only the promoters of BTG3 and FHL2 genes are methylated, with DAC inducing demethylation, suggesting DNA methylation directs repression of

  10. ABI1 and PP2CA Phosphatases Are Negative Regulators of Snf1-Related Protein Kinase1 Signaling in Arabidopsis[C][W

    PubMed Central

    Rodrigues, Américo; Adamo, Mattia; Crozet, Pierre; Margalha, Leonor; Confraria, Ana; Martinho, Cláudia; Elias, Alexandre; Rabissi, Agnese; Lumbreras, Victoria; González-Guzmán, Miguel; Antoni, Regina; Rodriguez, Pedro L.; Baena-González, Elena

    2013-01-01

    Plant survival under environmental stress requires the integration of multiple signaling pathways into a coordinated response, but the molecular mechanisms underlying this integration are poorly understood. Stress-derived energy deprivation activates the Snf1-related protein kinases1 (SnRK1s), triggering a vast transcriptional and metabolic reprogramming that restores homeostasis and promotes tolerance to adverse conditions. Here, we show that two clade A type 2C protein phosphatases (PP2Cs), established repressors of the abscisic acid (ABA) hormonal pathway, interact with the SnRK1 catalytic subunit causing its dephosphorylation and inactivation. Accordingly, SnRK1 repression is abrogated in double and quadruple pp2c knockout mutants, provoking, similarly to SnRK1 overexpression, sugar hypersensitivity during early seedling development. Reporter gene assays and SnRK1 target gene expression analyses further demonstrate that PP2C inhibition by ABA results in SnRK1 activation, promoting SnRK1 signaling during stress and once the energy deficit subsides. Consistent with this, SnRK1 and ABA induce largely overlapping transcriptional responses. Hence, the PP2C hub allows the coordinated activation of ABA and energy signaling, strengthening the stress response through the cooperation of two key and complementary pathways. PMID:24179127

  11. Comprehensive gene expression atlas for the Arabidopsis MAP kinase signalling pathways.

    PubMed

    Menges, Margit; Dóczi, Róbert; Okrész, László; Morandini, Piero; Mizzi, Luca; Soloviev, Mikhail; Murray, James A H; Bögre, László

    2008-01-01

    * Mitogen activated protein kinase (MAPK) pathways are signal transduction modules with layers of protein kinases having c. 120 genes in Arabidopsis, but only a few have been linked experimentally to functions. * We analysed microarray expression data for 114 MAPK signalling genes represented on the ATH1 Affymetrix arrays; determined their expression patterns during development, and in a wide range of time-course microarray experiments for their signal-dependent transcriptional regulation and their coregulation with other signalling components and transcription factors. * Global expression correlation of the MAPK genes with each of the represented 21 692 Arabidopsis genes was determined by calculating Pearson correlation coefficients. To group MAPK signalling genes based on similarities in global regulation, we performed hierarchical clustering on the pairwise correlation values. This should allow inferring functional information from well-studied MAPK components to functionally uncharacterized ones. Statistical overrepresentation of specific gene ontology (GO) categories in the gene lists showing high expression correlation values with each of the MAPK components predicted biological themes for the gene functions. * The combination of these methods provides functional information for many uncharacterized MAPK genes, and a framework for complementary future experimental dissection of the function of this complex family.

  12. Digital Signal Processing and Control for the Study of Gene Networks

    PubMed Central

    Shin, Yong-Jun

    2016-01-01

    Thanks to the digital revolution, digital signal processing and control has been widely used in many areas of science and engineering today. It provides practical and powerful tools to model, simulate, analyze, design, measure, and control complex and dynamic systems such as robots and aircrafts. Gene networks are also complex dynamic systems which can be studied via digital signal processing and control. Unlike conventional computational methods, this approach is capable of not only modeling but also controlling gene networks since the experimental environment is mostly digital today. The overall aim of this article is to introduce digital signal processing and control as a useful tool for the study of gene networks. PMID:27102828

  13. Digital Signal Processing and Control for the Study of Gene Networks.

    PubMed

    Shin, Yong-Jun

    2016-04-22

    Thanks to the digital revolution, digital signal processing and control has been widely used in many areas of science and engineering today. It provides practical and powerful tools to model, simulate, analyze, design, measure, and control complex and dynamic systems such as robots and aircrafts. Gene networks are also complex dynamic systems which can be studied via digital signal processing and control. Unlike conventional computational methods, this approach is capable of not only modeling but also controlling gene networks since the experimental environment is mostly digital today. The overall aim of this article is to introduce digital signal processing and control as a useful tool for the study of gene networks.

  14. Digital Signal Processing and Control for the Study of Gene Networks

    NASA Astrophysics Data System (ADS)

    Shin, Yong-Jun

    2016-04-01

    Thanks to the digital revolution, digital signal processing and control has been widely used in many areas of science and engineering today. It provides practical and powerful tools to model, simulate, analyze, design, measure, and control complex and dynamic systems such as robots and aircrafts. Gene networks are also complex dynamic systems which can be studied via digital signal processing and control. Unlike conventional computational methods, this approach is capable of not only modeling but also controlling gene networks since the experimental environment is mostly digital today. The overall aim of this article is to introduce digital signal processing and control as a useful tool for the study of gene networks.

  15. NJ cluster analysis of the SnRK2, PYR/PYL/RCAR, and ABF genes in Tibetan hulless barley.

    PubMed

    Yuan, H J; Wang, Y L; Wei, Z X; Xu, Q J; Zeng, X Q; Tang, Y W; Nyima, T S

    2016-11-03

    The abscisic acid (ABA) signaling pathway is known as one of the most important signaling pathways in plants and is mediated by multiple regulators. The genes SnRK2, PYR/PYL/RCAR, and ABF are relevant to both ABA-dependent and -independent signaling pathways. To elucidate the profile of these genes from Tibetan hulless barley (Hordeum vulgare L. var. nudum Hook. f.), we collected available sequences from RNA-Seq data, together with NCBI data from five other model plant species (Arabidopsis thaliana, Brachypodium distachyon, Oryza sativa, Populus trichocarpa, and Sorghum bicolor). Gene trees of SnRK2, PYR/PYL/RCAR, and ABF were constructed using a neighbor joining (NJ) method. For all genes, we identified a dominant group in which all six species were represented. Three, four, and five groups were found in the NJ trees of SnRK2, PYR/PYL/RCAR, and ABF, respectively. For each gene, Tibetan hulless barley was divided into three groups. Our analyses indicated that Tibetan hulless barley was associated with B. distachyon. The NJ cluster analysis also suggested that Tibetan hulless barley was affiliated with S. bicolor (SnRK2), A. thaliana (PYR/PYL/RCAR), and O. sativa (ABF). These results illustrate a diverse expression of genes SnRK2, PYR/PYL/RCAR, and ABF, and suggest a relationship among the six species studied. Collectively, our characterization of the three components of the ABA signaling pathway may contribute to improve stress tolerance in Tibetan hulless barley.

  16. Cross-talk in abscisic acid signaling

    NASA Technical Reports Server (NTRS)

    Fedoroff, Nina V.

    2002-01-01

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

  17. Allantoin, a stress-related purine metabolite, can activate jasmonate signaling in a MYC2-regulated and abscisic acid-dependent manner

    PubMed Central

    Takagi, Hiroshi; Ishiga, Yasuhiro; Watanabe, Shunsuke; Konishi, Tomokazu; Egusa, Mayumi; Akiyoshi, Nobuhiro; Matsuura, Takakazu; Mori, Izumi C.; Hirayama, Takashi; Kaminaka, Hironori; Shimada, Hiroshi; Sakamoto, Atsushi

    2016-01-01

    Allantoin is a metabolic intermediate of purine catabolism that often accumulates in stressed plants. Recently, we used Arabidopsis knockout mutants (aln) of ALLANTOINASE to show that this purine metabolite activates abscisic acid (ABA) production, thereby stimulating stress-related gene expression and enhancing seedling tolerance to abiotic stress. A detailed re-examination of the microarray data of an aln mutant (aln-1) confirmed the increased expression of ABA-related genes and also revealed altered expression of genes involved in jasmonic acid (JA) responses, probably under the control of MYC2, a master switch in the JA signaling pathway. Consistent with the transcriptome profiles, the aln-1 mutant displayed increased JA levels and enhanced responses to mechanical wounding and exogenous JA. Moreover, aln mutants demonstrated modestly increased susceptibility to Pseudomonas syringae and Pectobacterium carotovorum, probably reflecting the antagonistic action of MYC2 on the defense against these bacterial phytopathogens. Exogenously administered allantoin elicited the expression of JA-responsive genes, including MYC2, in wild-type plants, supporting the idea that allantoin might be responsible for the observed JA-related phenotypes of aln mutants. However, mutants deficient in bioactive JA (jar1-1), insensitive to JA (myc2-3), or deficient in ABA (aba2-1 and bglu18) suppressed the effect of exogenous allantoin. The suppression was further confirmed in aln-1 jar1-1 and aln-1 bglu18 double mutants. These results indicate that allantoin can activate the MYC2-regulated JA signaling pathway through ABA production. Overall, this study suggests a possible connection of purine catabolism with stress hormone homeostasis and signaling, and highlights the potential importance of allantoin in these interactions. PMID:26931169

  18. A misexpression screen identifies genes that can modulate RAS1 pathway signaling in Drosophila melanogaster.

    PubMed Central

    Huang, A M; Rubin, G M

    2000-01-01

    Differentiation of the R7 photoreceptor cell is dependent on the Sevenless receptor tyrosine kinase, which activates the RAS1/mitogen-activated protein kinase signaling cascade. Kinase suppressor of Ras (KSR) functions genetically downstream of RAS1 in this signal transduction cascade. Expression of dominant-negative KSR (KDN) in the developing eye blocks RAS pathway signaling, prevents R7 cell differentiation, and causes a rough eye phenotype. To identify genes that modulate RAS signaling, we screened for genes that alter RAS1/KSR signaling efficiency when misexpressed. In this screen, we recovered three known genes, Lk6, misshapen, and Akap200. We also identified seven previously undescribed genes; one encodes a novel rel domain member of the NFAT family, and six encode novel proteins. These genes may represent new components of the RAS pathway or components of other signaling pathways that can modulate signaling by RAS. We discuss the utility of gain-of-function screens in identifying new components of signaling pathways in Drosophila. PMID:11063696

  19. PzsS3a, a novel endosperm specific promoter from maize (Zea mays L.) induced by ABA.

    PubMed

    Hu, Yu-Feng; Li, Yang-ping; Zhang, Junjie; Liu, Hanmei; Chen, Zhiyu; Huang, Yubi

    2011-07-01

    The maize zsS3a gene codes for starch synthase. Transcriptional analysis revealed that it is mainly expressed in endosperm and is induced by abscisic acid (ABA). The 5'-flanking region of zsS3a was isolated, and a 1772 bp zsS3a promoter (PzsS3a) was fused to a Luc reporter gene with a maize Adh1 intron. Transient expression assay by bombardment transformation showed that, although the addition of the Adh1 intron enhanced the promoter activity approx. 52-fold, it did not alter the promoter specificity. PzsS3a with the Adh1 intron drove the Luc gene preferentially and it was highly expressed in the endosperm relative to the embryo but not in the leaf or root. Furthermore, the promoter activity in the endosperm was enhanced four fold by 100 mM ABA.

  20. Effective Boolean dynamics analysis to identify functionally important genes in large-scale signaling networks.

    PubMed

    Trinh, Hung-Cuong; Kwon, Yung-Keun

    2015-11-01

    Efficiently identifying functionally important genes in order to understand the minimal requirements of normal cellular development is challenging. To this end, a variety of structural measures have been proposed and their effectiveness has been investigated in recent literature; however, few studies have shown the effectiveness of dynamics-based measures. This led us to investigate a dynamic measure to identify functionally important genes, and the effectiveness of which was verified through application on two large-scale human signaling networks. We specifically consider Boolean sensitivity-based dynamics against an update-rule perturbation (BSU) as a dynamic measure. Through investigations on two large-scale human signaling networks, we found that genes with relatively high BSU values show slower evolutionary rate and higher proportions of essential genes and drug targets than other genes. Gene-ontology analysis showed clear differences between the former and latter groups of genes. Furthermore, we compare the identification accuracies of essential genes and drug targets via BSU and five well-known structural measures. Although BSU did not always show the best performance, it effectively identified the putative set of genes, which is significantly different from the results obtained via the structural measures. Most interestingly, BSU showed the highest synergy effect in identifying the functionally important genes in conjunction with other measures. Our results imply that Boolean-sensitive dynamics can be used as a measure to effectively identify functionally important genes in signaling networks.

  1. Bundle-sheath cell regulation of xylem-mesophyll water transport via aquaporins under drought stress: a target of xylem-borne ABA?

    PubMed

    Shatil-Cohen, Arava; Attia, Ziv; Moshelion, Menachem

    2011-07-01

    The hydraulic conductivity of the leaf vascular system (K(leaf) ) is dynamic and decreases rapidly under drought stress, possibly in response to the stress phytohormone ABA, which increases sharply in the xylem sap (ABA(xyl) ) during periods of drought. Vascular bundle-sheath cells (BSCs; a layer of parenchymatous cells tightly enwrapping the entire leaf vasculature) have been hypothesized to control K(leaf) via the specific activity of BSC aquaporins (AQPs). We examined this hypothesis and provide evidence for drought-induced ABA(xyl) diminishing BSC osmotic water permeability (P(f) ) via downregulated activity of their AQPs. ABA fed to the leaf via the xylem (petiole) both decreased K(leaf) and led to stomatal closure, replicating the effect of drought. In contrast, smearing ABA on the leaf blade, while also closing stomata, did not decrease K(leaf) within 2-3 h of application, demonstrating that K(leaf) does not depend entirely on stomatal closure. GFP-labeled BSCs showed decreased P(f) in response to 'drought' and ABA treatment, and a reversible decrease with HgCl(2) (an AQP blocker). These P(f) responses, absent in mesophyll cells, suggest stress-regulated AQP activity specific to BSCs, and imply a role for these cells in decreasing K(leaf) via a reduction in P(f) . Our results support the above hypothesis and highlight the BSCs as hitherto overlooked vasculature sensor compartments, extending throughout the leaf and functioning as 'stress-regulated valves' converting vasculature chemical signals (possibly ABA(xyl) ) into leaf hydraulic signals.

  2. Arabidopsis ABA-Activated Kinase MAPKKK18 is Regulated by Protein Phosphatase 2C ABI1 and the Ubiquitin-Proteasome Pathway.

    PubMed

    Mitula, Filip; Tajdel, Malgorzata; Cieśla, Agata; Kasprowicz-Maluśki, Anna; Kulik, Anna; Babula-Skowrońska, Danuta; Michalak, Michal; Dobrowolska, Grazyna; Sadowski, Jan; Ludwików, Agnieszka

    2015-12-01

    Phosphorylation and dephosphorylation events play an important role in the transmission of the ABA signal. Although SnRK2 [sucrose non-fermenting1-related kinase2] protein kinases and group A protein phosphatase type 2C (PP2C)-type phosphatases constitute the core ABA pathway, mitogen-activated protein kinase (MAPK) pathways are also involved in plant response to ABA. However, little is known about the interplay between MAPKs and PP2Cs or SnRK2 in the regulation of ABA pathways. In this study, an effort was made to elucidate the role of MAP kinase kinase kinase18 (MKKK18) in relation to ABA signaling and response. The MKKK18 knockout lines showed more vigorous root growth, decreased abaxial stomatal index and increased stomatal aperture under normal growth conditions, compared with the control wild-type Columbia line. In addition to transcriptional regulation of the MKKK18 promoter by ABA, we demonstrated using in vitro and in vivo kinase assays that the kinase activity of MKKK18 was regulated by ABA. Analysis of the cellular localization of MKKK18 showed that the active kinase was targeted specifically to the nucleus. Notably, we identified abscisic acid insensitive 1 (ABI1) PP2C as a MKKK18-interacting protein, and demonstrated that ABI1 inhibited its activity. Using a cell-free degradation assay, we also established that MKKK18 was unstable and was degraded by the proteasome pathway. The rate of MKKK18 degradation was delayed in the ABI1 knockout line. Overall, we provide evidence that ABI1 regulates the activity and promotes proteasomal degradation of MKKK18.

  3. Arabidopsis ABA-Activated Kinase MAPKKK18 is Regulated by Protein Phosphatase 2C ABI1 and the Ubiquitin–Proteasome Pathway

    PubMed Central

    Mitula, Filip; Tajdel, Malgorzata; Cieśla, Agata; Kasprowicz-Maluśki, Anna; Kulik, Anna; Babula-Skowrońska, Danuta; Michalak, Michal; Dobrowolska, Grazyna; Sadowski, Jan; Ludwików, Agnieszka

    2015-01-01

    Phosphorylation and dephosphorylation events play an important role in the transmission of the ABA signal. Although SnRK2 [sucrose non-fermenting1-related kinase2] protein kinases and group A protein phosphatase type 2C (PP2C)-type phosphatases constitute the core ABA pathway, mitogen-activated protein kinase (MAPK) pathways are also involved in plant response to ABA. However, little is known about the interplay between MAPKs and PP2Cs or SnRK2 in the regulation of ABA pathways. In this study, an effort was made to elucidate the role of MAP kinase kinase kinase18 (MKKK18) in relation to ABA signaling and response. The MKKK18 knockout lines showed more vigorous root growth, decreased abaxial stomatal index and increased stomatal aperture under normal growth conditions, compared with the control wild-type Columbia line. In addition to transcriptional regulation of the MKKK18 promoter by ABA, we demonstrated using in vitro and in vivo kinase assays that the kinase activity of MKKK18 was regulated by ABA. Analysis of the cellular localization of MKKK18 showed that the active kinase was targeted specifically to the nucleus. Notably, we identified abscisic acid insensitive 1 (ABI1) PP2C as a MKKK18-interacting protein, and demonstrated that ABI1 inhibited its activity. Using a cell-free degradation assay, we also established that MKKK18 was unstable and was degraded by the proteasome pathway. The rate of MKKK18 degradation was delayed in the ABI1 knockout line. Overall, we provide evidence that ABI1 regulates the activity and promotes proteasomal degradation of MKKK18. PMID:26443375

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

    PubMed Central

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

    2016-01-01

    Plants are sessile organisms, and their growth and development is detrimentally affected by environmental stresses such as drought and high salinity. Defense mechanisms are tightly regulated and complex processes, which respond to changing environmental conditions; however, the precise mechanisms that function under adverse conditions remain unclear. Here, we report the identification and functional characterization of the CaOSR1 gene, which functions in the adaptive response to abiotic stress. We found that CaOSR1 gene expression in pepper leaves was up-regulated after exposure to abscisic acid (ABA), drought, and high salinity. In addition, we demonstrated that the fusion protein of CaOSR1 with green fluorescent protein (GFP) is localized in the nucleus. We used CaOSR1-silenced pepper plants and CaOSR1-OX-overexpressing (OX) transgenic Arabidopsis plants to show that the CaOSR1 protein regulates the osmotic stress response. CaOSR1-silenced pepper plants showed increased drought susceptibility, and this was accompanied by a high transpiration rate. CaOSR1-OX plants displayed phenotypes that were hypersensitive to ABA and hyposensitive to osmotic stress, during the seed germination and seedling growth stages; furthermore, these plants exhibited enhanced drought tolerance at the adult stage, and this was characterized by higher leaf temperatures and smaller stomatal apertures because of ABA hypersensitivity. Taken together, our data indicate that CaOSR1 positively regulates osmotic stress tolerance via ABA-mediated cell signaling. These findings suggest an involvement of a novel protein in ABA and osmotic stress signalings in plants. PMID:27446121

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

    PubMed

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

    2016-01-01

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

  6. Dopamine Dynamics and Signaling in Drosophila: An Overview of Genes, Drugs and Behavioral Paradigms

    PubMed Central

    Yamamoto, Shinya; Seto, Elaine S.

    2014-01-01

    Changes in dopamine (DA) signaling have been implicated in a number of human neurologic and psychiatric disorders. Similarly, defects in DA signaling in the fruit fly, Drosophila melanogaster, have also been associated with several behavioral defects. As most genes involved in DA synthesis, transport, secretion, and signaling are conserved between species, Drosophila is a powerful genetic model organism to study the regulation of DA signaling in vivo. In this review, we will provide an overview of the genes and drugs that regulate DA biology in Drosophila. Furthermore, we will discuss the behavioral paradigms that are regulated by DA signaling in flies. By analyzing the genes and neuronal circuits that govern such behaviors using sophisticated genetic, pharmacologic, electrophysiologic, and imaging approaches in Drosophila, we will likely gain a better understanding about how this neuromodulator regulates motor tasks and cognition in humans. PMID:24770636

  7. The molecular basis of ABA-independent inhibition of PP2Cs by a subclass of PYL proteins.

    PubMed

    Hao, Qi; Yin, Ping; Li, Wenqi; Wang, Li; Yan, Chuangye; Lin, Zhaohu; Wu, Jim Zhen; Wang, Jiawei; Yan, S Frank; Yan, Nieng

    2011-06-10

    PYR1/PYL/RCAR proteins (PYLs) are confirmed abscisic acid (ABA) receptors, which inhibit protein phosphatase 2C (PP2C) upon binding to ABA. Arabidopsis thaliana has 14 PYLs, yet their functional distinction remains unclear. Here, we report systematic biochemical characterization of PYLs. A subclass of PYLs, represented by PYL10, inhibited PP2C in the absence of any ligand. Crystal structures of PYL10, both in the free form and in the HAB1 (PP2C)-bound state, revealed the structural basis for its constitutive activity. Structural-guided biochemical analyses revealed that ABA-independent inhibition of PP2C requires the PYLs to exist in a monomeric state. In addition, the residues guarding the entrance to the ligand-binding pocket of these PYLs should be bulky and hydrophobic. Based on these principles, we were able to generate monomeric PYL2 variants that gained constitutive inhibitory effect on PP2Cs. These findings provide an important framework for understanding the complex regulation of ABA signaling by PYL proteins.

  8. ABA flow modelling in Ricinus communis exposed to salt stress and variable nutrition

    PubMed Central

    Peuke, Andreas D.

    2016-01-01

    In a series of experiments with Ricinus communis, abscisic acid (ABA) concentrations in tissues and transport saps, its de novo biosynthesis, long-distance transport, and metabolism (degradation) were affected by nutritional conditions, nitrogen (N) source, and nutrient limitation, or salt stress. In the present study these data were statistically re-evaluated, and new correlations presented that underpin the importance of this universal phytohormone. The biggest differences in ABA concentration were observed in xylem sap. N source had the strongest effect; however, nutrient limitation (particularly phosphorus limitation) and salt also had significant effects. ABA was found in greater concentration in phloem sap compared with xylem sap; however, the effect of treatment on ABA concentration in phloem was lower. In the leaves, ABA concentration was most variable compared with the other tissues. This variation was only affected by the N source. In roots, ABA was significantly decreased by nutrient limitation. Of the compartments in which ABA was quantified, xylem sap ABA concentration was most significantly correlated with leaf stomatal conductance and leaf growth. Additionally, ABA concentration in xylem was significantly correlated to that in phloem, indicating a 6-fold concentration increase from xylem to phloem. The ABA flow model showed that biosynthesis of ABA in roots affected the xylem flow of ABA. Moreover, ABA concentration in xylem affected the degradation of the phytohormone in shoots and also its export from shoots via phloem. The role of phloem transport is discussed since it stimulates ABA metabolism in roots. PMID:27440939

  9. Anti-transpirant activity in xylem sap from flooded tomato (Lycopersicon esculentum Mill.) plants is not due to pH-mediated redistributions of root- or shoot-sourced ABA.

    PubMed

    Else, Mark A; Taylor, June M; Atkinson, Christopher J

    2006-01-01

    In flooded soils, the rapid effects of decreasing oxygen availability on root metabolic activity are likely to generate many potential chemical signals that may impact on stomatal apertures. Detached leaf transpiration tests showed that filtered xylem sap, collected at realistic flow rates from plants flooded for 2 h and 4 h, contained one or more factors that reduced stomatal apertures. The closure could not be attributed to increased root output of the glucose ester of abscisic acid (ABA-GE), since concentrations and deliveries of ABA conjugates were unaffected by soil flooding. Although xylem sap collected from the shoot base of detopped flooded plants became more alkaline within 2 h of flooding, this rapid pH change of 0.5 units did not alter partitioning of root-sourced ABA sufficiently to prompt a transient increase in xylem ABA delivery. More shoot-sourced ABA was detected in the xylem when excised petiole sections were perfused with pH 7 buffer, compared with pH 6 buffer. Sap collected from the fifth oldest leaf of "intact" well-drained plants and plants flooded for 3 h was more alkaline, by approximately 0.4 pH units, than sap collected from the shoot base. Accordingly, xylem [ABA] was increased 2-fold in sap collected from the fifth oldest petiole compared with the shoot base of flooded plants. However, water loss from transpiring, detached leaves was not reduced when the pH of the feeding solution containing 3-h-flooded [ABA] was increased from 6.7 to 7.1 Thus, the extent of the pH-mediated, shoot-sourced ABA redistribution was not sufficient to raise xylem [ABA] to physiologically active levels. Using a detached epidermis bioassay, significant non-ABA anti-transpirant activity was also detected in xylem sap collected at intervals during the first 24 h of soil flooding.

  10. Variations in the mycorrhization characteristics in roots of wild-type and ABA-deficient tomato are accompanied by specific transcriptomic alterations.

    PubMed

    Garrido, José Manuel García; Morcillo, Rafael Jorge León; Rodríguez, José Angel Martín; Bote, Juan Antonio Ocampo

    2010-05-01

    Abscissic acid (ABA) determines mycorrhiza functionality and arbuscule development. In this study, we performed transcriptome analysis in response to different mycorrhization status according to the ABA content in the root to identify genes that may play a role in arbuscule functionality. Affymetrix Tomato GeneChip (approximately 10,000 probes) allowed us to detect and compare the transcriptional root profiling of tomato (Solanum lycopersicum) wild-type and ABA-deficient sitiens plants colonized by Glomus intraradices. A number of identified genes in tomato belong to a category of genes already described as "mycorrhizal core-set" in other host plants. The impairment in arbuscular mycorrhiza (AM) formation in ABA-deficient mutants was associated with upregulation of genes related to defense and cell wall modification, whereas functional mycorrhization in wild-type plants was associated with activation of genes related to isoprenoid metabolism. The oxylipin pathway was activated in tomato mycorrhizal roots at late stages of interaction, and was related to the control of fungal spread in roots, not with the establishment of the symbiosis. Induction of selected genes, representing a range of biological functions and representative of the three sets of genes specifically upregulated in the different plant phenotype, was confirmed by quantitative reverse-transcription polymerase chain reaction, and their response to phythohormone treatment was tested, showing that ethylene and jasmonic acid are key regulators of gene expression during AM development. Comparative analysis of mycorrhiza upregulated functional categories revealed significant changes in gene expression associated with the different mycorrhization status according to the ABA content in the roots.

  11. Insulin signaling genes modulate nicotine-induced behavioral responses in C. elegans

    PubMed Central

    Wescott, Seth A.; Ronan, Elizabeth A.; Xu, X.Z. Shawn

    2015-01-01

    Insulin signaling has been suggested to modulate nicotine dependence, but the underlying genetic evidence has been lacking. Here, we used the nematode, C. elegans, to investigate whether genetic alterations in the insulin signaling pathway affect behavioral responses to nicotine. To do so, we challenged drug-naïve C. elegans with an acute dose of nicotine [100 μM] while recording changes in their locomotion speed. While nicotine treatment stimulated locomotion speed in wild-type C. elegans, the same treatment reduced locomotion speed in mutants defective in insulin signaling. This phenotype could be suppressed by mutations in daf-16, a gene encoding a FOXO transcription factor that acts downstream of insulin signaling. Our data suggest that insulin signaling genes, daf-2, age-1, pdk-1, akt-1, and akt-2 modulate behavioral responses to nicotine in C. elegans, revealing a genetic link between nicotine behavior and insulin signaling. PMID:26317299

  12. Mutations in the F-box gene SNEEZY result in decreased arabidopsis GA signaling

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We previously reported that the SLEEPY1 (SLY1) homolog, F-box gene SNEEZY/SLEEPY2 (SNE/SLY2), can partly replace SLY1 in gibberellin (GA) hormone signaling through interaction with DELLAs RGA and GAI. To determine whether SNE normally functions in GA signaling, we characterized the phenotypes of tw...

  13. Variation in opsin genes correlates with signalling ecology in North American fireflies.

    PubMed

    Sander, S E; Hall, D W

    2015-09-01

    Genes underlying signal reception should evolve to maximize signal detection in a particular environment. In animals, opsins, the protein component of visual pigments, are predicted to evolve according to this expectation. Fireflies are known for their bioluminescent mating signals. The eyes of nocturnal species are expected to maximize the detection of conspecific signal colours emitted in the typical low-light environment. This is not expected for species that have transitioned to diurnal activity in bright daytime environments. Here, we test the hypothesis that opsin gene sequence plays a role in modifying firefly eye spectral sensitivity. We use genome and transcriptome sequencing in four firefly species, transcriptome sequencing in six additional species and targeted gene sequencing in 28 other species to identify all opsin genes present in North American fireflies and to elucidate amino acid sites under positive selection. We also determine whether amino acid substitutions in opsins are linked to evolutionary changes in signal mode, signal colour and light environment. We find only two opsins, one long wavelength and one ultraviolet, in all firefly species and identify 25 candidate sites that may be involved in determining spectral sensitivity. In addition, we find elevated rates of evolution at transitions to diurnal activity, and changes in selective constraint on long wavelength opsin associated with changes in light environment. Our results suggest that changes in eye spectral sensitivity are at least partially due to opsin sequence. Fireflies continue to be a promising system in which to investigate the evolution of signals, receptors and signalling environments.

  14. Variation in opsin genes correlates with signaling ecology in North American fireflies

    PubMed Central

    Sander, Sarah E.; Hall, David W.

    2015-01-01

    Genes underlying signal reception should evolve to maximize signal detection in a particular environment. In animals, opsins, the protein component of visual pigments, are predicted to evolve according to this expectation. Fireflies are known for their bioluminescent mating signals. The eyes of nocturnal species are expected to maximize detection of conspecific signal colors emitted in the typical low-light environment. This is not expected for species that have transitioned to diurnal activity in bright daytime environments. Here we test the hypothesis that opsin gene sequence plays a role in modifying firefly eye spectral sensitivity. We use genome and transcriptome sequencing in four firefly species, transcriptome sequencing in six additional species, and targeted gene sequencing in 28 other species to identify all opsin genes present in North American fireflies and to elucidate amino acid sites under positive selection. We also determine whether amino acid substitutions in opsins are linked to evolutionary changes in signal mode, signal color, and light environment. We find only two opsins, one long wavelength and one ultraviolet, in all firefly species and identify 25 candidate sites that may be involved in determining spectral sensitivity. In addition, we find elevated rates of evolution at transitions to diurnal activity, and changes in selective constraint on LW opsin associated with changes in light environment. Our results suggest that changes in eye spectral sensitivity are at least partially due to opsin sequence. Fireflies continue to be a promising system in which to investigate the evolution of signals, receptors, and signaling environments. PMID:26289828

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

    PubMed Central

    Park, Yong-Soon; Bae, Dong-Won; Ryu, Choong-Min

    2015-01-01

    Up to now, the potential underlying molecular mechanisms by which maize (Zea mays L.) plants elicit defense responses by infestation with a phloem feeding insect whitefly [Bemisia tabaci (Genn.)] have been barely elucidated against (a)biotic stresses. To fill this gap of current knowledge maize plants were infested with whitefly and these plants were subsequently assessed the levels of water loss. To understand the mode of action, plant hormone contents and the stress-related mRNA expression were evaluated. Whitefly-infested maize plants did not display any significant phenotypic differences in above-ground tissues (infested site) compared with controls. By contrast, root (systemic tissue) biomass was increased by 2-fold by whitefly infestation. The levels of endogenous indole-3-acetic acid (IAA), jasmonic acid (JA), and hydrogen peroxide (H2O2) were significantly higher in whitefly-infested plants. The biosynthetic or signaling-related genes for JA and anthocyanins were highly up-regulated. Additionally, we found that healthier plants were obtained in whitefly-infested plants under drought conditions. The weight of whitefly-infested plants was approximately 20% higher than that of control plants at 14 d of drought treatment. The drought tolerance-related genes, ZmbZIP72, ZmSNAC1, and ZmABA1, were highly expressed in the whitefly-infected plants. Collectively, our results suggest that IAA/JA-derived maize physiological changes and correlation of H2O2 production and water loss are modulated by above-ground whitefly infestation in maize plants. PMID:26630288

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

    PubMed

    Park, Yong-Soon; Bae, Dong-Won; Ryu, Choong-Min

    2015-01-01

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

  17. Assessment battery for communication (ABaCo): normative data.

    PubMed

    Angeleri, Romina; Bosco, Francesca M; Gabbatore, Ilaria; Bara, Bruno G; Sacco, Katiuscia

    2012-09-01

    The Assessment Battery for Communication (ABaCo) was introduced to evaluate pragmatic abilities in patients with cerebral lesions. The battery is organized into five evaluation scales focusing on separate components of pragmatic competence. In the present study, we present normative data for individuals 15-75 years of age (N = 300). The sample was stratified by age, sex, and years of education, according to Italian National Institute of Statistics indications in order to be representative of the general national population. Since performance on the ABaCo decreases with age and lower years of education, the norms were stratified for both age and education. The ABaCo is a valuable tool in clinical practice; the normative data provided here will enable clinicians to determine different kinds and specific levels of communicative impairments more precisely.

  18. NFAT Targets Signaling Molecules to Gene Promoters in Pancreatic β-Cells

    PubMed Central

    Borenstein-Auerbach, Nofit; McGlynn, Kathleen; Kunnathodi, Faisal; Shahbazov, Rauf; Syed, Ilham; Kanak, Mazhar; Takita, Morihito; Levy, Marlon F.; Naziruddin, Bashoo

    2015-01-01

    Nuclear factor of activated T cells (NFAT) is activated by calcineurin in response to calcium signals derived by metabolic and inflammatory stress to regulate genes in pancreatic islets. Here, we show that NFAT targets MAPKs, histone acetyltransferase p300, and histone deacetylases (HDACs) to gene promoters to differentially regulate insulin and TNF-α genes. NFAT and ERK associated with the insulin gene promoter in response to glucagon-like peptide 1, whereas NFAT formed complexes with p38 MAPK (p38) and Jun N-terminal kinase (JNK) upon promoters of the TNF-α gene in response to IL-1β. Translocation of NFAT and MAPKs to gene promoters was calcineurin/NFAT dependent, and complex stability required MAPK activity. Knocking down NFATc2 expression, eliminating NFAT DNA binding sites, or interfering with NFAT nuclear import prevented association of MAPKs with gene promoters. Inhibiting p38 and JNK activity increased NFAT-ERK association with promoters, which repressed TNF-α and enhanced insulin gene expression. Moreover, inhibiting p38 and JNK induced a switch from NFAT-p38/JNK-histone acetyltransferase p300 to NFAT-ERK-HDAC3 complex formation upon the TNF-α promoter, which resulted in gene repression. Histone acetyltransferase/HDAC exchange was reversed on the insulin gene by p38/JNK inhibition in the presence of glucagon-like peptide 1, which enhanced gene expression. Overall, these data indicate that NFAT directs signaling enzymes to gene promoters in islets, which contribute to protein-DNA complex stability and promoter regulation. Furthermore, the data suggest that TNF-α can be repressed and insulin production can be enhanced by selectively targeting signaling components of NFAT-MAPK transcriptional/signaling complex formation in pancreatic β-cells. These findings have therapeutic potential for suppressing islet inflammation while preserving islet function in diabetes and islet transplantation. PMID:25496032

  19. Mechanical control of cyclic AMP signalling and gene transcription through integrins

    NASA Technical Reports Server (NTRS)

    Meyer, C. J.; Alenghat, F. J.; Rim, P.; Fong, J. H.; Fabry, B.; Ingber, D. E.

    2000-01-01

    This study was carried out to discriminate between two alternative hypotheses as to how cells sense mechanical forces and transduce them into changes in gene transcription. Do cells sense mechanical signals through generalized membrane distortion or through specific transmembrane receptors, such as integrins? Here we show that mechanical stresses applied to the cell surface alter the cyclic AMP signalling cascade and downstream gene transcription by modulating local release of signals generated by activated integrin receptors in a G-protein-dependent manner, whereas distortion of integrins in the absence of receptor occupancy has no effect.

  20. Hypergravity signal transduction and gene expression in cultured mammalian cells

    NASA Technical Reports Server (NTRS)

    Kumei, Y.; Whitson, P. A.

    1994-01-01

    A number of studies have been conducted during space flight and with clinostats and centrifuges, suggesting that gravity effects the proliferation and differentiation of mammalian cells in vitro. However, little is known about the mechanisms by which mammalian cells respond to changes in gravitational stress. This paper summarizes studies designed to clarify the effects of hypergravity on the cultured human HeLa cells and to investigate the mechanism of hypergravity signal transduction in these cells.

  1. Overexpression of Arabidopsis molybdenum cofactor sulfurase gene confers drought tolerance in maize (Zea mays L.).

    PubMed

    Lu, Yao; Li, Yajun; Zhang, Jiachang; Xiao, Yitao; Yue, Yuesen; Duan, Liusheng; Zhang, Mingcai; Li, Zhaohu

    2013-01-01

    Abscisic acid (ABA) is a key component of the signaling system that integrates plant adaptive responses to abiotic stress. Overexpression of Arabidopsis molybdenum cofactor sulfurase gene (LOS5) in maize markedly enhanced the expression of ZmAO and aldehyde oxidase (AO) activity, leading to ABA accumulation and increased drought tolerance. Transgenic maize (Zea mays L.) exhibited the expected reductions in stomatal aperture, which led to decreased water loss and maintenance of higher relative water content (RWC) and leaf water potential. Also, transgenic maize subjected to drought treatment exhibited lower leaf wilting, electrolyte leakage, malondialdehyde (MDA) and H(2)O(2) content, and higher activities of antioxidative enzymes and proline content compared to wild-type (WT) maize. Moreover, overexpression of LOS5 enhanced the expression of stress-regulated genes such as Rad 17, NCED1, CAT1, and ZmP5CS1 under drought stress conditions, and increased root system development and biomass yield after re-watering. The increased drought tolerance in transgenic plants was associated with ABA accumulation via activated AO and expression of stress-related gene via ABA induction, which sequentially induced a set of favorable stress-related physiological and biochemical responses.

  2. Molecular evolution, characterization, and expression analysis of SnRK2 gene family in Pak-choi (Brassica rapa ssp. chinensis)

    PubMed Central

    Huang, Zhinan; Tang, Jun; Duan, Weike; Wang, Zhen; Song, Xiaoming; Hou, Xilin

    2015-01-01

    The sucrose non-fermenting 1-related protein kinase 2 (SnRK2) family members are plant-specific serine/threonine kinases that are involved in the plant response to abiotic stress and abscisic acid (ABA)-dependent plant development. Further understanding of the evolutionary history and expression characteristics of these genes will help to elucidate the mechanisms of the stress tolerance in Pak-choi, an important green leafy vegetable in China. Thus, we investigated the evolutionary patterns, footprints and conservation of SnRK2 genes in selected plants and later cloned and analyzed SnRK2 genes in Pak-choi. We found that this gene family was preferentially retained in Brassicas after the Brassica-Arabidopsis thaliana split. Next, we cloned and sequenced 13 SnRK2 from both cDNA and DNA libraries of stress-induced Pak-choi, which were under conditions of ABA, salinity, cold, heat, and osmotic treatments. Most of the BcSnRK2s have eight exons and could be divided into three groups. The subcellular localization predictions suggested that the putative BcSnRK2 proteins were enriched in the nucleus. The results of an analysis of the expression patterns of the BcSnRK2 genes showed that BcSnRK2 group III genes were robustly induced by ABA treatments. Most of the BcSnRK2 genes were activated by low temperature, and the BcSnRK2.6 genes responded to both ABA and low temperature. In fact, most of the BcSnRK2 genes showed positive or negative regulation under ABA and low temperature treatments, suggesting that they may be global regulators that function at the intersection of multiple signaling pathways to play important roles in Pak-choi stress responses. PMID:26557127

  3. The Top 10 Reasons Children With Autism Deserve ABA

    PubMed Central

    Walsh, Mary Beth

    2011-01-01

    We who advocate for applied behavior analysis (ABA) for children with autism spectrum disorders often construct our arguments based on the scientific evidence. However, the audience that most needs to hear this argument, that is, the parents of children, especially very young children, diagnosed with autism, may not be convinced by the science alone. This essay attempts to make the case for the multiple benefits of ABA intervention through the use of humor and anecdotes couched in a “Top Ten List,” and illustrating most points with stories of an engaging child with autism (my son, Ben). PMID:22532906

  4. Functional characterization and hormonal regulation of the PHEOPHYTINASE gene LpPPH controlling leaf senescence in perennial ryegrass

    PubMed Central

    Zhang, Jing; Yu, Guohui; Wen, Wuwu; Ma, Xiqing; Xu, Bin; Huang, Bingru

    2016-01-01

    Chlorophyll (Chl) degradation occurs naturally during leaf maturation and senescence, and can be induced by stresses, both processes involving the regulation of plant hormones. The objective of this study was to determine the functional roles and hormonal regulation of a gene encoding pheophytin pheophorbide hydrolyase (PPH) that catabolizes Chl degradation during leaf senescence in perennial grass species. A PPH gene, LpPPH, was cloned from perennial ryegrass (Lolium perenne L.). LpPPH was localized in the chloroplast. Overexpressing LpPPH accelerated Chl degradation in wild tobacco, and rescued the stay-green phenotype of the Arabidopsis pph null mutant. The expression level of LpPPH was positively related to the extent of leaf senescence. Exogenous application of abscisic acid (ABA) and ethephon (an ethylene-releasing agent) accelerated the decline in Chl content in leaves of perennial ryegrass, whereas cytokinin (CK) and aminoethoxyvinylglycine (AVG; an ethylene biosynthesis inhibitor) treatments suppressed leaf senescence, corresponding to the up- or down-regulation of LpPPH expression. The promoters of five orthologous PPH genes were predicted to share conserved cis-elements potentially recognized by transcription factors in the ABA and CK pathways. Taken together, the results suggested that LpPPH-mediated Chl breakdown could be regulated positively by ABA and ethylene, and negatively by CK, and LpPPH could be a direct downstream target gene of transcription factors in the ABA and CK signaling pathways. PMID:26643195

  5. HOM-C genes, Wnt signaling and axial patterning in the C. elegans posterior ventral epidermis.

    PubMed

    Li, Xin; Kulkarni, Rashmi P; Hill, Russell J; Chamberlin, Helen M

    2009-08-01

    Wnt signaling and HOM-C/Hox genes pattern cell fate along the anterior/posterior axis in many animals. In general, Wnt signaling participates in establishing the anterior/posterior axis, whereas HOM-C genes confer regional identities to cells along the axis. However, recent work in non-bilaterial metazoans suggests that the ancestral patterning system relied on Wnts, with a later co-option of HOM-C genes to replace Wnts in regional patterning. Here we provide direct experimental support for this model from C. elegans, where a regional Wnt patterning system is uncovered in HOM-C gene mutants. Anterior/posterior patterning of P11/P12 cell fate in the C. elegans tail is normally dependent on the HOM-C gene egl-5/Abdominal-B. If the HOM-C gene mab-5/fushi tarazu is also mutant, however, a Wnt signal can promote P12 fate in the absence of egl-5. Furthermore, transcription of egl-5 in the P12.pa cell is influenced by an autoregulatory element that is essential in wild type, but not in mab-5 egl-5 double mutants, identifying regulatory parallels between P12 cell fate specification and egl-5 transcriptional regulation in the P12 lineage. Together, our results identify complex regulatory relationships among signaling pathways and HOM-C genes, and uncover a layering of patterning systems that may reflect their evolutionary history.

  6. T Cell Receptor-Independent Basal Signaling via Erk and Abl Kinases Suppresses RAG Gene Expression

    PubMed Central

    Roose, Jeroen P; Diehn, Maximilian; Tomlinson, Michael G; Lin, Joseph; Alizadeh, Ash A; Botstein, David; Brown, Patrick O

    2003-01-01

    Signal transduction pathways guided by cellular receptors commonly exhibit low-level constitutive signaling in a continuous, ligand-independent manner. The dynamic equilibrium of positive and negative regulators establishes such a tonic signal. Ligand-independent signaling by the precursors of mature antigen receptors regulates development of B and T lymphocytes. Here we describe a basal signal that controls gene expression profiles in the Jurkat T cell line and mouse thymocytes. Using DNA microarrays and Northern blots to analyze unstimulated cells, we demonstrate that expression of a cluster of genes, including RAG-1 and RAG-2, is repressed by constitutive signals requiring the adapter molecules LAT and SLP-76. This TCR-like pathway results in constitutive low-level activity of Erk and Abl kinases. Inhibition of Abl by the drug STI-571 or inhibition of signaling events upstream of Erk increases RAG-1 expression. Our data suggest that physiologic gene expression programs depend upon tonic activity of signaling pathways independent of receptor ligation. PMID:14624253

  7. A membrane-bound NAC transcription factor as an integrator of biotic and abiotic stress signals.

    PubMed

    Seo, Pil Joon; Park, Chung-Mo

    2010-05-01

    Transcription factors are central components of gene regulatory networks that mediate virtually all aspects of growth and developmental processes in biological systems. The activity of transcription factors is regulated at multiple steps, such as gene transcription, posttranscriptional RNA processing, posttranslational modification, protein-protein interactions, and controlled protein turnover. Controlled activation of dormant, membrane-bound transcription factor (MTF) is an intriguing regulatory mechanism that ensures quick transcriptional responses to environmental fluctuations in plants, in which various stress hormones serve as signaling mediators. NTL6 is proteolytically activated upon exposure to cold and induces expression of the Pathogenesis-Related (PR) genes. The membrane-mediated cold signaling in inducing pathogen resistance is considered to be an adaptive strategy that protects plants against infection by hydrophilic pathogens frequently occurring during cold season. We found that NTL6 also mediates abscisic acid (ABA) regulation of abiotic stress responses in Arabidopsis. NTL6 is proteolytically activated by ABA. Transgenic plants overexpressing a nuclear NTL6 form (35S:6ΔC) exhibited a hypersensitive response to ABA and high salinity in seed germination. Taken together, these observations indicate that NTL6 plays an integrative role in plant responses to both biotic and abiotic stress conditions.

  8. Seasonal abscisic acid signal and a basic leucine zipper transcription factor, DkbZIP5, regulate proanthocyanidin biosynthesis in persimmon fruit.

    PubMed

    Akagi, Takashi; Katayama-Ikegami, Ayako; Kobayashi, Shozo; Sato, Akihiko; Kono, Atsushi; Yonemori, Keizo

    2012-02-01

    Proanthocyanidins (PAs) are secondary metabolites that contribute to plant protection and crop quality. Persimmon (Diospyros kaki) has a unique characteristic of accumulating large amounts of PAs, particularly in its fruit. Normal astringent-type and mutant nonastringent-type fruits show different PA accumulation patterns depending on the seasonal expression patterns of DkMyb4, which is a Myb transcription factor (TF) regulating many PA pathway genes in persimmon. In this study, attempts were made to identify the factors involved in DkMyb4 expression and the resultant PA accumulation in persimmon fruit. Treatment with abscisic acid (ABA) and an ABA biosynthesis inhibitor resulted in differential changes in the expression patterns of DkMyb4 and PA biosynthesis in astringent-type and nonastringent-type fruits depending on the development stage. To obtain an ABA-signaling TF, we isolated a full-length basic leucine zipper (bZIP) TF, DkbZIP5, which is highly expressed in persimmon fruit. We also showed that ectopic DkbZIP5 overexpression in persimmon calluses induced the up-regulation of DkMyb4 and the resultant PA biosynthesis. In addition, a detailed molecular characterization using the electrophoretic mobility shift assay and transient reporter assay indicated that DkbZIP5 recognized ABA-responsive elements in the promoter region of DkMyb4 and acted as a direct regulator of DkMyb4 in an ABA-dependent manner. These results suggest that ABA signals may be involved in PA biosynthesis in persimmon fruit via DkMyb4 activation by DkbZIP5.

  9. TNFα signals through specialized factories where responsive coding and miRNA genes are transcribed

    PubMed Central

    Papantonis, Argyris; Kohro, Takahide; Baboo, Sabyasachi; Larkin, Joshua D; Deng, Binwei; Short, Patrick; Tsutsumi, Shuichi; Taylor, Stephen; Kanki, Yasuharu; Kobayashi, Mika; Li, Guoliang; Poh, Huay-Mei; Ruan, Xiaoan; Aburatani, Hiroyuki; Ruan, Yijun; Kodama, Tatsuhiko; Wada, Youichiro; Cook, Peter R

    2012-01-01

    Tumour necrosis factor alpha (TNFα) is a potent cytokine that signals through nuclear factor kappa B (NFκB) to activate a subset of human genes. It is usually assumed that this involves RNA polymerases transcribing responsive genes wherever they might be in the nucleus. Using primary human endothelial cells, variants of chromosome conformation capture (including 4C and chromatin interaction analysis with paired-end tag sequencing), and fluorescence in situ hybridization to detect single nascent transcripts, we show that TNFα induces responsive genes to congregate in discrete ‘NFκB factories'. Some factories further specialize in transcribing responsive genes encoding micro-RNAs that target downregulated mRNAs. We expect all signalling pathways to contain this extra leg, where responding genes are transcribed in analogous specialized factories. PMID:23103767

  10. OsRACK1 Is Involved in Abscisic Acid- and H2O2-Mediated Signaling to Regulate Seed Germination in Rice (Oryza sativa, L.)

    PubMed Central

    Zhang, Dongping; Chen, Li; Li, Dahong; Lv, Bing; Chen, Yun; Chen, Jingui; XuejiaoYan; Liang, Jiansheng

    2014-01-01

    The receptor for activated C kinase 1 (RACK1) is one member of the most important WD repeat–containing family of proteins found in all eukaryotes and is involved in multiple signaling pathways. However, compared with the progress in the area of mammalian RACK1, our understanding of the functions and molecular mechanisms of RACK1 in the regulation of plant growth and development is still in its infancy. In the present study, we investigated the roles of rice RACK1A gene (OsRACK1A) in controlling seed germination and its molecular mechanisms by generating a series of transgenic rice lines, of which OsRACK1A was either over-expressed or under-expressed. Our results showed that OsRACK1A positively regulated seed germination and negatively regulated the responses of seed germination to both exogenous ABA and H2O2. Inhibition of ABA biosynthesis had no enhancing effect on germination, whereas inhibition of ABA catabolism significantly suppressed germination. ABA inhibition on seed germination was almost fully recovered by exogenous H2O2 treatment. Quantitative analyses showed that endogenous ABA levels were significantly higher and H2O2 levels significantly lower in OsRACK1A-down regulated transgenic lines as compared with those in wildtype or OsRACK1A-up regulated lines. Quantitative real-time PCR analyses showed that the transcript levels of OsRbohs and amylase genes, RAmy1A and RAmy3D, were significantly lower in OsRACK1A-down regulated transgenic lines. It is concluded that OsRACK1A positively regulates seed germination by controlling endogenous levels of ABA and H2O2 and their interaction. PMID:24865690

  11. Integrated module and gene-specific regulatory inference implicates upstream signaling networks.

    PubMed

    Roy, Sushmita; Lagree, Stephen; Hou, Zhonggang; Thomson, James A; Stewart, Ron; Gasch, Audrey P

    2013-01-01

    Regulatory networks that control gene expression are important in diverse biological contexts including stress response and development. Each gene's regulatory program is determined by module-level regulation (e.g. co-regulation via the same signaling system), as well as gene-specific determinants that can fine-tune expression. We present a novel approach, Modular regulatory network learning with per gene information (MERLIN), that infers regulatory programs for individual genes while probabilistically constraining these programs to reveal module-level organization of regulatory networks. Using edge-, regulator- and module-based comparisons of simulated networks of known ground truth, we find MERLIN reconstructs regulatory programs of individual genes as well or better than existing approaches of network reconstruction, while additionally identifying modular organization of the regulatory networks. We use MERLIN to dissect global transcriptional behavior in two biological contexts: yeast stress response and human embryonic stem cell differentiation. Regulatory modules inferred by MERLIN capture co-regulatory relationships between signaling proteins and downstream transcription factors thereby revealing the upstream signaling systems controlling transcriptional responses. The inferred networks are enriched for regulators with genetic or physical interactions, supporting the inference, and identify modules of functionally related genes bound by the same transcriptional regulators. Our method combines the strengths of per-gene and per-module methods to reveal new insights into transcriptional regulation in stress and development.

  12. Integrated Module and Gene-Specific Regulatory Inference Implicates Upstream Signaling Networks

    PubMed Central

    Roy, Sushmita; Lagree, Stephen; Hou, Zhonggang; Thomson, James A.; Stewart, Ron; Gasch, Audrey P.

    2013-01-01

    Regulatory networks that control gene expression are important in diverse biological contexts including stress response and development. Each gene's regulatory program is determined by module-level regulation (e.g. co-regulation via the same signaling system), as well as gene-specific determinants that can fine-tune expression. We present a novel approach, Modular regulatory network learning with per gene information (MERLIN), that infers regulatory programs for individual genes while probabilistically constraining these programs to reveal module-level organization of regulatory networks. Using edge-, regulator- and module-based comparisons of simulated networks of known ground truth, we find MERLIN reconstructs regulatory programs of individual genes as well or better than existing approaches of network reconstruction, while additionally identifying modular organization of the regulatory networks. We use MERLIN to dissect global transcriptional behavior in two biological contexts: yeast stress response and human embryonic stem cell differentiation. Regulatory modules inferred by MERLIN capture co-regulatory relationships between signaling proteins and downstream transcription factors thereby revealing the upstream signaling systems controlling transcriptional responses. The inferred networks are enriched for regulators with genetic or physical interactions, supporting the inference, and identify modules of functionally related genes bound by the same transcriptional regulators. Our method combines the strengths of per-gene and per-module methods to reveal new insights into transcriptional regulation in stress and development. PMID:24146602

  13. Differential usage of signal transduction pathways defines two types of serum response factor target gene.

    PubMed

    Gineitis, D; Treisman, R

    2001-07-06

    Activation of the transcription factor serum response factor (SRF) is dependent on Rho-controlled changes in actin dynamics. We used pathway-specific inhibitors to compare the roles of actin dynamics, extracellular signal-regulated kinase (ERK) signaling, and phosphatidylinositol 3-kinase in signaling either to SRF itself or to four cellular SRF target genes. Serum, lysophosphatidic acid, platelet-derived growth factor, and phorbol 12-myristate 13-acetate (PMA) each activated transcription of a stably integrated SRF reporter gene dependent on functional RhoA GTPase. Inhibition of mitogen-activated protein kinase-ERK kinase (MEK) signalling reduced activation of the SRF reporter by all stimuli by about 50%, except for PMA, which was effectively blocked. Inhibition of phosphatidylinositol 3-kinase slightly reduced reporter activation by serum and lysophosphatidic acid but substantially inhibited activation by platelet-derived growth factor and PMA. Reporter induction by all stimuli was absolutely dependent on actin dynamics. Regulation of the SRF (srf) and vinculin (vcl) genes was similar to that of the SRF reporter gene; activation by all stimuli was Rho-dependent and required actin dynamics but was largely independent of MEK activity. In contrast, activation of fos and egr1 occurred independently of RhoA and actin polymerization but was almost completely dependent on MEK activation. These results show that at least two classes of SRF target genes can be distinguished on the basis of their relative sensitivity to RhoA-actin and MEK-ERK signaling pathways.

  14. Quorum activation at a distance: spatiotemporal patterns of gene regulation from diffusion of an autoinducer signal

    NASA Astrophysics Data System (ADS)

    Dilanji, Gabriel; Langebrake, Jessica; Deleenheer, Patrick; Hagen, Stephen J.

    2012-02-01

    Bacteria in colonies coordinate gene regulation through the exchange of diffusible signal molecules known as autoinducers (AI). This ``quorum signaling'' often occurs in physically heterogeneous and spatially extended environments such as biofilms. Under these conditions the space and time scales for diffusion of the signal limit the range and timing of effective gene regulation. We expect that spatial and temporal patterns of gene expression will reflect physical environmental constraints as well as nonlinear transcriptional activation and feedback within the gene regulatory system. We have combined experiments and modeling to investigate how these spatiotemporal patterns develop. We embed engineered plasmid/GFP quorum sensor strains or wild type strains in a long narrow agar lane, and then introduce AI signal at one terminus of the lane. Diffusion of the AI initiates reporter expression along the length of the lane, extending to macroscopic distances of mm-cm. Resulting patterns are captured quantitatively by a mathematical model that incorporates logistic growth of the population, diffusion of AI, and nonlinear transcriptional activation. Our results show that a diffusing quorum signal can coordinate gene expression over distances of order 1cm on time scales of order 10 hrs.

  15. ERK signaling pathway regulates sleep duration through activity-induced gene expression during wakefulness.

    PubMed

    Mikhail, Cyril; Vaucher, Angélique; Jimenez, Sonia; Tafti, Mehdi

    2017-01-24

    Wakefulness is accompanied by experience-dependent synaptic plasticity and an increase in activity-regulated gene transcription. Wake-induced genes are certainly markers of neuronal activity and may also directly regulate the duration of and need for sleep. We stimulated murine cortical cultures with the neuromodulatory signals that are known to control wakefulness in the brain and found that norepinephrine alone or a mixture of these neuromodulators induced activity-regulated gene transcription. Pharmacological inhibition of the various signaling pathways involved in the regulation of gene expression indicated that the extracellular signal-regulated kinase (ERK) pathway is the principal one mediating the effects of waking neuromodulators on gene expression. In mice, ERK phosphorylation in the cortex increased and decreased with wakefulness and sleep. Whole-body or cortical neuron-specific deletion of Erk1 or Erk2 significantly increased the duration of wakefulness in mice, and pharmacological inhibition of ERK phosphorylation decreased sleep duration and increased the duration of wakefulness bouts. Thus, this signaling pathway, which is highly conserved from Drosophila to mammals, is a key pathway that links waking experience-induced neuronal gene expression to sleep duration and quality.

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

    DTIC Science & Technology

    2011-01-01

    from the nucleus. GA ABA GA Water α- amylase Starch Sugar G ro w th Aleurone layer Endosperm Embryo GA ABA (a) (b) Figure 3 The enhanceosome and...repressosome model for the regula- tion of a- amylase gene expression during barley seed germination. (a) A schematic representation of seed germination...hydrolytic enzymes such as a- amylase . Stored starch is broken down by a- amylase , and soluble sugars are used by the germinating embryo. (b) ABA promotes

  17. ABA and Diverse Cultural and Linguistic Environments: A Welsh Perspective

    ERIC Educational Resources Information Center

    Jones, E. W.; Hoerger, M.; Hughes, J. C.; Williams, B. M.; Jones, B.; Moseley, Y.; Hughes, D. R.; Prys, D.

    2011-01-01

    Gwynedd Local Education Authority (LEA) in North West Wales, UK, is funding a small-scale autism-specific specialist education service using ABA methodology. The program is available through the medium of Welsh, English or bilingually, depending on the individual needs of the child (Jones and Hoerger in Eur J Behav Anal 10:249-253,…

  18. ABA, AAB and ABC Renewal in Taste Aversion Learning

    ERIC Educational Resources Information Center

    Bernal-Gamboa, Rodolfo; Juarez, Yectivani; Gonzalez-Martin, Gabriela; Carranza, Rodrigo; Sanchez-Carrasco, Livia; Nieto, Javier

    2012-01-01

    Context renewal is identified when the conditioned response (CR) elicited by an extinguished conditioned stimulus (CS) reappears as a result of changing the contextual cues during the test. Two experiments were designed for testing contextual renewal in a conditioned taste aversion preparation. Experiment 1 assessed ABA and AAB context renewal,…

  19. Adaptive Behaviour Assessment System: Indigenous Australian Adaptation Model (ABAS: IAAM)

    ERIC Educational Resources Information Center

    du Plessis, Santie

    2015-01-01

    The study objectives were to develop, trial and evaluate a cross-cultural adaptation of the Adaptive Behavior Assessment System-Second Edition Teacher Form (ABAS-II TF) ages 5-21 for use with Indigenous Australian students ages 5-14. This study introduced a multiphase mixed-method design with semi-structured and informal interviews, school…

  20. Personality Traits Associated with Occupational "Burnout" in ABA Therapists

    ERIC Educational Resources Information Center

    Hurt, Amy A.; Grist, Cathy Lann; Malesky, Lann A., Jr.; McCord, David M.

    2013-01-01

    Background: Applied behaviour analysis (ABA) therapists typically work one-to-one with children with autism for extended periods of time, which often leads to high levels of job-related stress, lower levels of job satisfaction, increased frequency of occupational "burnout" and higher than average job turnover (Journal of Autism…

  1. Dissociations among ABA, ABC, and AAB Recovery Effects

    ERIC Educational Resources Information Center

    Ungor, Metin; Lachnit, Harald

    2008-01-01

    In a human predictive learning experiment, the strengths of ABA, ABC, and AAB recovery effects after discrimination reversal learning were compared. Initially, a discrimination between two stimuli (X+, Y-) was trained in Context A. During Phase 2, participants received discrimination reversal training (X-, Y+) either in Context A (Group AAB) or in…

  2. ABA is required for the accumulation of APX1 and MBF1c during a combination of water deficit and heat stress

    PubMed Central

    Zandalinas, Sara I.; Balfagón, Damián; Arbona, Vicent; Gómez-Cadenas, Aurelio; Inupakutika, Madhuri A.; Mittler, Ron

    2016-01-01

    Abscisic acid (ABA) plays a key role in plant acclimation to abiotic stress. Although recent studies suggested that ABA could also be important for plant acclimation to a combination of abiotic stresses, its role in this response is currently unknown. Here we studied the response of mutants impaired in ABA signalling (abi1-1) and biosynthesis (aba1-1) to a combination of water deficit and heat stress. Both mutants displayed reduced growth, biomass, and survival when subjected to stress combination. Focusing on abi1-1, we found that although its stomata had an impaired response to water deficit, remaining significantly more open than wild type, its stomatal aperture was surprisingly reduced when subjected to the stress combination. Stomatal closure during stress combination in abi1-1 was accompanied by higher levels of H2O2 in leaves, suggesting that H2O2 might play a role in this response. In contrast to the almost wild-type stomatal closure phenotype of abi1-1 during stress combination, the accumulation of ascorbate peroxidase 1 and multiprotein bridging factor 1c proteins, required for acclimation to a combination of water deficit and heat stress, was significantly reduced in abi1-1. Our findings reveal a key function for ABA in regulating the accumulation of essential proteins during a combination of water deficit and heat stress. PMID:27497287

  3. ABA is required for the accumulation of APX1 and MBF1c during a combination of water deficit and heat stress.

    PubMed

    Zandalinas, Sara I; Balfagón, Damián; Arbona, Vicent; Gómez-Cadenas, Aurelio; Inupakutika, Madhuri A; Mittler, Ron

    2016-10-01

    Abscisic acid (ABA) plays a key role in plant acclimation to abiotic stress. Although recent studies suggested that ABA could also be important for plant acclimation to a combination of abiotic stresses, its role in this response is currently unknown. Here we studied the response of mutants impaired in ABA signalling (abi1-1) and biosynthesis (aba1-1) to a combination of water deficit and heat stress. Both mutants displayed reduced growth, biomass, and survival when subjected to stress combination. Focusing on abi1-1, we found that although its stomata had an impaired response to water deficit, remaining significantly more open than wild type, its stomatal aperture was surprisingly reduced when subjected to the stress combination. Stomatal closure during stress combination in abi1-1 was accompanied by higher levels of H2O2 in leaves, suggesting that H2O2 might play a role in this response. In contrast to the almost wild-type stomatal closure phenotype of abi1-1 during stress combination, the accumulation of ascorbate peroxidase 1 and multiprotein bridging factor 1c proteins, required for acclimation to a combination of water deficit and heat stress, was significantly reduced in abi1-1 Our findings reveal a key function for ABA in regulating the accumulation of essential proteins during a combination of water deficit and heat stress.

  4. Effects of high night temperature and abscisic acid (ABA) on rice (Oryza sativa L.) physiology

    Technology Transfer Automated Retrieval System (TEKTRAN)

    High night temperature (HNT) is known to decrease rice yields. The impact of abscisic acid (ABA) on plants has been the subject of many studies. However, little or no work has been carried out on rice response to ABA under HNT-stress conditions. This study determined the effects of ABA on rice leaf ...

  5. ABA and Instruction of Students with Autism Spectrum Disorders: Introduction to the Special Series.

    ERIC Educational Resources Information Center

    Heflin, L. Juane; Alberto, Paul A.

    2001-01-01

    This introductory article to this special issue on the use of applied behavior analysis (ABA) with autism spectrum disorders (ASD) notes the 40-year history of ABA strategy development, verification, and generalization. It briefly introduces the following articles, which are intended to illustrate the range of ABA applications and the depth of…

  6. Coping as a Predictor of Burnout and General Health in Therapists Working in ABA Schools

    ERIC Educational Resources Information Center

    Griffith, G. M.; Barbakou, A.; Hastings, R. P.

    2014-01-01

    Background: Little is known about the work-related well-being of applied behaviour analysis (ABA) therapists who work in school-based contexts and deliver ABA interventions to children with autism. Methods: A questionnaire on work-related stress (burnout), general distress, perceived supervisor support and coping was completed by 45 ABA therapists…

  7. Related to ABA-Insensitive3(ABI3)/Viviparous1 and AtABI5 transcription factor coexpression in cotton enhances drought stress adaptation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Drought tolerance is an important trait being pursued by the agbiotech industry. Abscisic acid (ABA) is a stress hormone that mediates a multitude of processes in growth and development, water use efficiency and gene expression during seed development and in response to environmental stresses. Arabi...

  8. Good genes, oxidative stress and condition-dependent sexual signals.

    PubMed Central

    von Schantz, T; Bensch, S; Grahn, M; Hasselquist, D; Wittzell, H

    1999-01-01

    The immune and the detoxication systems of animals are characterized by allelic polymorphisms, which underlie individual differences in ability to combat assaults from pathogens and toxic compounds. Previous studies have shown that females may improve offspring survival by selecting mates on the basis of sexual ornaments and signals that honestly reveal health. In many cases the expression of these ornaments appears to be particularly sensitive to oxidative stress. Activated immune and detoxication systems often generate oxidative stress by an extensive production of reactive metabolites and free radicals. Given that tolerance or resistance to toxic compounds and pathogens can be inherited, female choice should promote the evolution of male ornaments that reliably reveal the status of the bearers' level of oxidative stress. Hence, oxidative stress may be one important agent linking the expression of sexual ornaments to genetic variation in fitness-related traits, thus promoting the evolution of female mate choice and male sexual ornamentation, a controversial issue in evolutionary biology ever since Darwin. PMID:10081154

  9. Heparan sulfate biosynthetic gene Ndst1 is required for FGF signaling in early lens development.

    PubMed

    Pan, Yi; Woodbury, Andrea; Esko, Jeffrey D; Grobe, Kay; Zhang, Xin

    2006-12-01

    Multiple signaling molecules, including bone morphogenic proteins (BMP) and fibroblast growth factors (FGF), play important roles in early lens development. However, how these morphogens are regulated is still largely unknown. Heparan sulfate participates in both morphogen transport and morphogen-receptor interaction. In this study, we demonstrate that inactivation of the heparan sulfate biosynthetic gene Ndst1 resulted in invagination defects of the early lens and in the disruption of lens-determination gene expression, leading to severe lens hypoplasia or anophthalmia. Ndst1 mutants exhibited reduced sulfation of heparan sulfate, but both BMP- and Wnt-signaling remained unchanged. Instead, these embryos showed diminished binding of a subset of FGF proteins to FGF receptors. Consistent with disruption of FGF signaling, expression of phospho-Erk and ERM were also downregulated in Ndst1-mutant lenses. Taken together, these results establish an important role of Ndst1 function in FGF signaling during lens development.

  10. Arabidopsis CBL interacting protein kinase 3 interacts with ABR1, an APETALA2 domain transcription factor, to regulate ABA responses.

    PubMed

    Sanyal, Sibaji K; Kanwar, Poonam; Yadav, Akhilesh K; Sharma, Cheshta; Kumar, Ashish; Pandey, Girdhar K

    2017-01-01

    Calcium (Ca(2+)) plays a vital role as a second messenger in several signaling pathways in plants. The calcineurin B-like proteins (CBLs) represent a family of plant calcium-binding proteins that function in propagating Ca(2+) signals by interacting with CBL interacting protein kinases (CIPKs). Phosphorylation of CBL by CIPK is essential for the module to display full activity towards its target protein. Previous genetic analysis showed that the function of CBL9-CIPK3 module was implicated in negatively regulating seed germination and early development. In the present study, we have biochemically investigated the interaction of CBL9-CIPK3 module and our findings show that CBL9 is phosphorylated by CIPK3. Moreover, Abscisic acid repressor 1 (ABR1) is identified as the downstream target of CIPK3 and CIPK3-ABR1 function to regulate ABA responses during seed germination. Our study also indicates that the role of ABR1 is not limited to seed germination but it also regulates the ABA dependent processes in the adult stage of plant development. Combining our results, we conclude that the CBL9-CIPK3-ABR1 pathway functions to regulate seed germination and ABA dependent physiological processes in Arabidopsis.

  11. New cross talk between ROS, ABA and auxin controlling seed maturation and germination unraveled in APX6 deficient Arabidopsis seeds.

    PubMed

    Chen, Changming; Twito, Shir; Miller, Gad

    2014-01-01

    Successful execution of germination program greatly depends on the seeds' oxidative homeostasis. We recently identified new roles for the H2O2-reducing enzyme ascorbate peroxidase 6 (APX6) in germination control and seeds' stress tolerance. APX6 replaces APX1 as the dominant APX in dry seeds, and its loss-of-function results in reduced germination due to over accumulation of ROS and oxidative damage. Metabolic analyses in dry apx6 seeds, revealed altered homeostasis of primary metabolites including accumulation of TCA cycle metabolites, ABA and auxin, supporting a novel role for APX6 in regulating cellular metabolism. Increased sensitivity of apx6 mutants to ABA or IAA in germination assays indicated impaired perception of these signals. Relative suppression of ABI3 and ABI5 expression, and induction of ABI4, suggested the activation of a signaling route inhibiting germination in apx6 seeds that is independent of ABI3. Here we provide additional evidence linking ABI4 with ABA- and auxin-controlled inhibition of germination and suggest a hypothetical model for the role of APX6 in the regulation of the crosstalk between these hormones and ROS.

  12. The Notch-2 Gene Is Regulated by Wnt Signaling in Cultured Colorectal Cancer Cells

    PubMed Central

    Ungerbäck, Jonas; Elander, Nils; Grünberg, John; Sigvardsson, Mikael; Söderkvist, Peter

    2011-01-01

    Background Notch and Wnt pathways are key regulators of intestinal homeostasis and alterations in these pathways may lead to the development of colorectal cancer (CRC). In CRC the Apc/β-catenin genes in the Wnt signaling pathway are frequently mutated and active Notch signaling contributes to tumorigenesis by keeping the epithelial cells in a proliferative state. These pathways are simultaneously active in proliferative adenoma cells and a crosstalk between them has previously been suggested in normal development as well as in cancer. Principal Findings In this study, in silico analysis of putative promoters involved in transcriptional regulation of genes coding for proteins in the Notch signaling pathway revealed several putative LEF-1/TCF sites as potential targets for β-catenin and canonical Wnt signaling. Further results from competitive electrophoretic mobility-shift assay (EMSA) studies suggest binding of several putative sites in Notch pathway gene promoters to in vitro translated β-catenin/Lef-1. Wild type (wt)-Apc negatively regulates β-catenin. By induction of wt-Apc or β-catenin silencing in HT29 cells, we observed that several genes in the Notch pathway, including Notch-2, were downregulated. Finally, active Notch signaling was verified in the ApcMin/+ mouse model where Hes-1 mRNA levels were found significantly upregulated in intestinal tumors compared to normal intestinal mucosa. Luciferase assays showed an increased activity for the core and proximal Notch-2 promoter upon co-transfection of HCT116 cells with high expression recombinant Tcf-4, Lef-1 or β-catenin. Conclusions In this paper, we identified Notch-2 as a novel target for β-catenin-dependent Wnt signaling. Furthermore our data supports the notion that additional genes in the Notch pathway might be transcriptionally regulated by Wnt signaling in colorectal cancer. PMID:21437251

  13. Profiling of sugar transporter genes in grapevine coping with water deficit.

    PubMed

    Medici, Anna; Laloi, Maryse; Atanassova, Rossitza

    2014-11-03

    The profiling of grapevine (Vitis vinifera L.) genes under water deficit was specifically targeted to sugar transporters. Leaf water status was characterized by physiological parameters and soluble sugars content. The expression analysis provided evidence that VvHT1 hexose transporter gene was strongly down-regulated by the increased sugar content under mild water-deficit. The genes of monosaccharide transporter VvHT5, sucrose carrier VvSUC11, vacuolar invertase VvGIN2 and grape ASR (ABA, stress, ripening) were up-regulated under severe water stress. Their regulation in a drought-ABA signalling network and possible roles in complex interdependence between sugar subcellular partitioning and cell influx/efflux under Grapevine acclimation to dehydration are discussed.

  14. Plant gravitropic signal transduction: A network analysis leads to gene discovery

    NASA Astrophysics Data System (ADS)

    Wyatt, Sarah

    Gravity plays a fundamental role in plant growth and development. Although a significant body of research has helped define the events of gravity perception, the role of the plant growth regulator auxin, and the mechanisms resulting in the gravity response, the events of signal transduction, those that link the biophysical action of perception to a biochemical signal that results in auxin redistribution, those that regulate the gravitropic effects on plant growth, remain, for the most part, a “black box.” Using a cold affect, dubbed the gravity persistent signal (GPS) response, we developed a mutant screen to specifically identify components of the signal transduction pathway. Cloning of the GPS genes have identified new proteins involved in gravitropic signaling. We have further exploited the GPS response using a multi-faceted approach including gene expression microarrays, proteomics analysis, and bioinformatics analysis and continued mutant analysis to identified additional genes, physiological and biochemical processes. Gene expression data provided the foundation of a regulatory network for gravitropic signaling. Based on these gene expression data and related data sets/information from the literature/repositories, we constructed a gravitropic signaling network for Arabidopsis inflorescence stems. To generate the network, both a dynamic Bayesian network approach and a time-lagged correlation coefficient approach were used. The dynamic Bayesian network added existing information of protein-protein interaction while the time-lagged correlation coefficient allowed incorporation of temporal regulation and thus could incorporate the time-course metric from the data set. Thus the methods complemented each other and provided us with a more comprehensive evaluation of connections. Each method generated a list of possible interactions associated with a statistical significance value. The two networks were then overlaid to generate a more rigorous, intersected

  15. Wnt signaling induces transcription, spatial proximity, and translocation of fusion gene partners in human hematopoietic cells.

    PubMed

    Ugarte, Giorgia D; Vargas, Macarena F; Medina, Matías A; León, Pablo; Necuñir, David; Elorza, Alvaro A; Gutiérrez, Soraya E; Moon, Randall T; Loyola, Alejandra; De Ferrari, Giancarlo V

    2015-10-08

    Chromosomal translocations are frequently associated with a wide variety of cancers, particularly hematologic malignancies. A recurrent chromosomal abnormality in acute myeloid leukemia is the reciprocal translocation t(8;21) that fuses RUNX1 and ETO genes. We report here that Wnt/β-catenin signaling increases the expression of ETO and RUNX1 genes in human hematopoietic progenitors. We found that β-catenin is rapidly recruited into RNA polymerase II transcription factories (RNAPII-Ser5) and that ETO and RUNX1 genes are brought into close spatial proximity upon Wnt3a induction. Notably, long-term treatment of cells with Wnt3a induces the generation a frequent RUNX1-ETO translocation event. Thus, Wnt/β-catenin signaling induces transcription and translocation of RUNX1 and ETO fusion gene partners, opening a novel window to understand the onset/development of leukemia.

  16. Association of Single Nucleotide Polymorphisms in Wnt Signaling Pathway Genes with Breast Cancer in Saudi Patients

    PubMed Central

    Shaik, Jilani Purusottapatnam; Alabdulkarim, Huda A.; Ajaj, Sana Abdulla; Khan, Zahid

    2013-01-01

    Breast cancer is a complex heterogeneous disease involving genetic and epigenetic alterations in genes encoding proteins that are components of various signaling pathways. Candidate gene approach have identified association of genetic variants in the Wnt signaling pathway genes and increased susceptibility to several diseases including breast cancer. Due to the rarity of somatic mutations in key genes of Wnt pathway, we investigated the association of genetic variants in these genes with predisposition to breast cancers. We performed a case-control study to identify risk variants by examining 15 SNPs located in 8 genes associated with Wnt signaling. Genotypic analysis of individual locus showed statistically significant association of five SNPs located in β-catenin, AXIN2, DKK3, SFRP3 and TCF7L2 with breast cancers. Increased risk was observed only with the SNP in β-catenin while the other four SNPs conferred protection against breast cancers. Majority of these associations persisted after stratification of the cases based on estrogen receptor status and age of on-set of breast cancer. The rs7775 SNP in exon 6 of SFRP3 gene that codes for either arginine or glycine exhibited very strong association with breast cancer, even after Bonferroni's correction. Apart from these five variants, rs3923086 in AXIN2 and rs3763511 in DKK4 that did not show any association in the overall population were significantly associated with early on-set and estrogen receptor negative breast cancers, respectively. This is the first study to utilize pathway based approach to identify association of risk variants in the Wnt signaling pathway genes with breast cancers. Confirmation of our findings in larger populations of different ethnicities would provide evidence for the role of Wnt pathway as well as screening markers for early detection of breast carcinomas. PMID:23516639

  17. Association of single nucleotide polymorphisms in Wnt signaling pathway genes with breast cancer in Saudi patients.

    PubMed

    Alanazi, Mohammad Saud; Parine, Narasimha Reddy; Shaik, Jilani Purusottapatnam; Alabdulkarim, Huda A; Ajaj, Sana Abdulla; Khan, Zahid

    2013-01-01

    Breast cancer is a complex heterogeneous disease involving genetic and epigenetic alterations in genes encoding proteins that are components of various signaling pathways. Candidate gene approach have identified association of genetic variants in the Wnt signaling pathway genes and increased susceptibility to several diseases including breast cancer. Due to the rarity of somatic mutations in key genes of Wnt pathway, we investigated the association of genetic variants in these genes with predisposition to breast cancers. We performed a case-control study to identify risk variants by examining 15 SNPs located in 8 genes associated with Wnt signaling. Genotypic analysis of individual locus showed statistically significant association of five SNPs located in β-catenin, AXIN2, DKK3, SFRP3 and TCF7L2 with breast cancers. Increased risk was observed only with the SNP in β-catenin while the other four SNPs conferred protection against breast cancers. Majority of these associations persisted after stratification of the cases based on estrogen receptor status and age of on-set of breast cancer. The rs7775 SNP in exon 6 of SFRP3 gene that codes for either arginine or glycine exhibited very strong association with breast cancer, even after Bonferroni's correction. Apart from these five variants, rs3923086 in AXIN2 and rs3763511 in DKK4 that did not show any association in the overall population were significantly associated with early on-set and estrogen receptor negative breast cancers, respectively. This is the first study to utilize pathway based approach to identify association of risk variants in the Wnt signaling pathway genes with breast cancers. Confirmation of our findings in larger populations of different ethnicities would provide evidence for the role of Wnt pathway as well as screening markers for early detection of breast carcinomas.

  18. Thyroid hormone signalling genes are regulated by photoperiod in the hypothalamus of F344 rats.

    PubMed

    Ross, Alexander W; Helfer, Gisela; Russell, Laura; Darras, Veerle M; Morgan, Peter J

    2011-01-01

    Seasonal animals adapt their physiology and behaviour in anticipation of climate change to optimise survival of their offspring. Intra-hypothalamic thyroid hormone signalling plays an important role in seasonal responses in mammals and birds. In the F344 rat, photoperiod stimulates profound changes in food intake, body weight and reproductive status. Previous investigations of the F344 rat have suggested a role for thyroid hormone metabolism, but have only considered Dio2 expression, which was elevated in long day photoperiods. Microarray analysis was used to identify time-dependent changes in photoperiod responsive genes, which may underlie the photoperiod-dependent phenotypes of the juvenile F344 rat. The most significant changes are those related to thyroid hormone metabolism and transport. Using photoperiod manipulations and melatonin injections into long day photoperiod (LD) rats to mimic short day (SD), we show photoinduction and photosuppression gene expression profiles and melatonin responsiveness of genes by in situ hybridization; TSHβ, CGA, Dio2 and Oatp1c1 genes were all elevated in LD whilst in SD, Dio3 and MCT-8 mRNA were increased. NPY was elevated in SD whilst GALP increased in LD. The photoinduction and photosuppression profiles for GALP were compared to that of GHRH with GALP expression following GHRH temporally. We also reveal gene sets involved in photoperiodic responses, including retinoic acid and Wnt/ß-catenin signalling. This study extends our knowledge of hypothalamic regulation by photoperiod, by revealing large temporal changes in expression of thyroid hormone signalling genes following photoperiod switch. Surprisingly, large changes in hypothalamic thyroid hormone levels or TRH expression were not detected. Expression of NPY and GALP, two genes known to regulate GHRH, were also changed by photoperiod. Whether these genes could provide links between thyroid hormone signalling and the regulation of the growth axis remains to be

  19. Cooperation of multiple signaling pathways in CD40-regulated gene expression in B lymphocytes

    PubMed Central

    Dadgostar, Hajir; Zarnegar, Brian; Hoffmann, Alexander; Qin, Xiao-Feng; Truong, Uyen; Rao, Govinda; Baltimore, David; Cheng, Genhong

    2002-01-01

    CD40/CD40L interaction is essential for multiple biological events in T dependent humoral immune responses, including B cell survival and proliferation, germinal center and memory B cell formation, and antibody isotype switching and affinity maturation. By using high-density microarrays, we examined gene expression in primary mouse B lymphocytes after multiple time points of CD40L stimulation. In addition to genes involved in cell survival and growth, which are also induced by other mitogens such as lipopolysaccharide, CD40L specifically activated genes involved in germinal center formation and T cell costimulatory molecules that facilitate T dependent humoral immunity. Next, by examining the roles of individual CD40-activated signal transduction pathways, we dissected the overall CD40-mediated response into genes independently regulated by the individual pathways or collectively by all pathways. We also found that gene down-regulation is a significant part of the overall response and that the p38 pathway plays an important role in this process, whereas the NF-κB pathway is important for the up-regulation of primary response genes. Our finding of overlapping independent control of gene expression modules by different pathways suggests, in principle, that distinct biological behaviors that depend on distinct gene expression subsets can be manipulated by targeting specific signaling pathways. PMID:11830667

  20. A hierarchy of ECM-mediated signalling tissue-specific gene expression regulates tissue-specific gene expression

    SciTech Connect

    Roskelley, Calvin D; Srebrow, Anabella; Bissell, Mina J

    1995-10-07

    A dynamic and reciprocal flow of information between cells and the extracellular matrix contributes significantly to the regulation of form and function in developing systems. Signals generated by the extracellular matrix do not act in isolation. Instead, they are processed within the context of global signalling hierarchies whose constituent inputs and outputs are constantly modulated by all the factors present in the cell's surrounding microenvironment. This is particularly evident in the mammary gland, where the construction and subsequent destruction of such a hierarchy regulates changes in tissue-specific gene expression, morphogenesis and apoptosis during each developmental cycle of pregnancy, lactation and involution.

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

    PubMed

    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.

  2. The aba mutant of Arabidopsis thaliana is impaired in epoxy-carotenoid biosynthesis

    SciTech Connect

    Rock, C.D.; Zeevaart, J.A.D. )

    1991-09-01

    The three mutant alleles of the ABA locus of Arabidopsis thaliana result in plants that are deficient in the plant growth regulator abscisic acid (ABA). The authors have used {sup 18}O{sub 2} to label ABA in water-stressed leaves of mutant and wild-type Arabidopsis. Analysis by selected ion monitoring and tandem mass spectrometry of ({sup 18}O)ABA and its catabolites, phaseic acid and ABA-glucose ester ({beta}-D-glucopyranosyl abscisate), indicates that the aba genotypes are impaired in ABA biosynthesis and have a small ABA precursor pool of compounds that contain oxygens on the rings, presumably oxygenated carotenoids (xanthophylls). Quantitation of the carotenoids form mutant and wild-type leaves establishes that the aba alleles cause a deficiency of the epoxy-carotenoids violaxanthin and neoxanthin and an accumulation of their biosynthetic precursor, zeaxanthin. These results provide evidence that ABA is synthesized by oxidative cleavage of epoxy-carotenoids (the indirect pathway). Furthermore the carotenoid mutant they describe undergoes normal greening. Thus the aba alleles provide an opportunity to study the physiological roles of epoxy-carotenoids in photosynthesis in a higher plants.

  3. Identification and functional characterization of a type I signal peptidase gene of Bacillus megaterium DSM319.

    PubMed

    Nahrstedt, H; Wittchen, K- D; Rachman, M A; Meinhardt, F

    2004-04-01

    The sipM gene of Bacillus megaterium encoding a type I signal peptidase (SPase) was isolated and structurally characterized. RNA analysis revealed a transcript size in accordance with a bicistronic operon comprising sipM and an adjacent open reading frame. Inactivation of sipM by targeted gene disruption could not be achieved, indicating its essential role for cell viability since there might be no other type I SPase of major importance present in B. megaterium. Plasmid-assisted amplification of the gene resulted in an increase in activity of the heterologous glucanase used as an extracellular reporter, suggesting a potential bottleneck for protein secretion within this species.

  4. Variants of insulin-signaling inhibitor genes in type 2 diabetes and related metabolic abnormalities.

    PubMed

    de Lorenzo, Carlo; Greco, Annalisa; Fiorentino, Teresa Vanessa; Mannino, Gaia Chiara; Hribal, Marta Letizia

    2013-01-01

    Insulin resistance has a central role in the pathogenesis of several metabolic diseases, including type 2 diabetes, obesity, glucose intolerance, metabolic syndrome, atherosclerosis, and cardiovascular diseases. Insulin resistance and related traits are likely to be caused by abnormalities in the genes encoding for proteins involved in the composite network of insulin-signaling; in this review we have focused our attention on genetic variants of insulin-signaling inhibitor molecules. These proteins interfere with different steps in insulin-signaling: ENPP1/PC-1 and the phosphatases PTP1B and PTPRF/LAR inhibit the insulin receptor activation; INPPL1/SHIP-2 hydrolyzes PI3-kinase products, hampering the phosphoinositide-mediated downstream signaling; and TRIB3 binds the serine-threonine kinase Akt, reducing its phosphorylation levels. While several variants have been described over the years for all these genes, solid evidence of an association with type 2 diabetes and related diseases seems to exist only for rs1044498 of the ENPP1 gene and for rs2295490 of the TRIB3 gene. However, overall the data recapitulated in this Review article may supply useful elements to interpret the results of novel, more technically advanced genetic studies; indeed it is becoming increasingly evident that genetic information on metabolic diseases should be interpreted taking into account the complex biological pathways underlying their pathogenesis.

  5. Hedgehog signaling pathway regulated the target genes for adipogenesis in silkworm Bombyx mori.

    PubMed

    Liang, Shuang; Chen, Rui-Ting; Zhang, Deng-Pan; Xin, Hu-Hu; Lu, Yan; Wang, Mei-Xian; Miao, Yun-Gen

    2015-10-01

    Hedgehog (Hh) signals regulate invertebrate and vertebrate development, yet the role of the pathway in adipose development remains poorly understood. In this report, we found that Hh pathway components are expressed in the fat body of silkworm larvae. Functional analysis of these components in a BmN cell line model revealed that activation of the Hh gene stimulated transcription of Hh pathway components, but inhibited the expression of the adipose marker gene AP2. Conversely, specific RNA interference-mediated knockdown of Hh resulted in increased AP2 expression. This further showed the regulation of Hh signal on the adipose marker gene. In silkworm larval models, enhanced adipocyte differentiation and an increase in adipocyte cell size were observed in silkworms that had been treated with a specific Hh signaling pathway antagonist, cyclopamine. The fat-body-specific Hh blockade tests were consistent with Hh signaling inhibiting silkworm adipogenesis. Our results indicate that the role of Hh signaling in inhibiting fat formation is conserved in vertebrates and invertebrates.

  6. The novel C. elegans gene sop-3 modulates Wnt signaling to regulate Hox gene expression.

    PubMed

    Zhang, H; Emmons, S W

    2001-03-01

    We describe the properties of a new gene, sop-3, that is required for the regulated expression of a C. elegans Hox gene, egl-5, in a postembryonic neuroectodermal cell lineage. Regulated expression of egl-5 in this cell lineage is necessary for development of the sensory rays of the male tail. sop-3 encodes a predicted novel protein of 1475 amino acids without clear homologs in other organisms. However, the sequence contains motifs consisting of homopolymeric runs of amino acids found in several other transcriptional regulators, some of which also act in Hox gene regulatory pathways. The genetic properties of sop-3 are very similar to those of sop-1, which encodes a component of the transcriptional Mediator complex, and mutations in the two genes are synthetic lethal. This suggests that SOP-3 may act at the level of the Mediator complex in regulating transcription initiation. In a sop-3 loss-of-function background, egl-5 is expressed ectopically in lineage branches that normally do not express this gene. Such expression is dependent on the Hox gene mab-5, as it is in branches where egl-5 is normally expressed. Ectopic egl-5 expression is also dependent on the Wnt pathway. Thus, sop-3 contributes to the combinatorial control of egl-5 by blocking egl-5 activation by MAB-5 and the Wnt pathway in inappropriate lineage branches.

  7. SOX18 Is a Novel Target Gene of Hedgehog Signaling in Cervical Carcinoma Cell Lines

    PubMed Central

    Popovic, Jelena; Schwirtlich, Marija; Rankovic, Branislava; Stevanovic, Milena

    2015-01-01

    Although there is much evidence showing functional relationship between Hedgehog pathway, in particular Sonic hedgehog, and SOX transcription factors during embryonic development, scarce data are available regarding their crosstalk in cancer cells. SOX18 protein plays an important role in promoting tumor angiogenesis and therefore emerged as a promising potential target in antiangiogenic tumor therapy. Recently it became evident that expression of SOX18 gene in tumors is not restricted to endothelium of accompanying blood and lymphatic vessels, but in tumor cells as well.In this paper we have identified human SOX18 gene as a novel target gene of Hedgehog signaling in cervical carcinoma cell lines. We have presented data showing that expression of SOX18 gene is regulated by GLI1 and GLI2 transcription factors, final effectors of Hedgehog signaling, and that modulation of Hedgehog signaling activity in considerably influence SOX18 expression. We consider important that Hedgehog pathway inhibitors reduced SOX18 expression, thus showing, for the first time, possibility for manipulationwith SOX18 gene expression. In addition, we analyzed the role of SOX18 in malignant potential of cervical carcinoma cell line, and showed that its overexpression has no influence on cells proliferation and viability, but substantially promotes migration and invasion of cells in vitro. Pro-migratory effect of SOX18 suggests its role in promoting malignant spreading, possibly in response to Hedgehog activation. PMID:26588701

  8. Light signaling genes and their manipulation towards modulation of phytonutrient content in tomato fruits.

    PubMed

    Azari, Raviv; Tadmor, Yaakov; Meir, Ayala; Reuveni, Moshe; Evenor, Dalia; Nahon, Sahadia; Shlomo, Haviva; Chen, Lea; Levin, Ilan

    2010-01-01

    Due to its economic importance, ease of genetic manipulation, cultivation and processing, the tomato plant has been a target for increasing and diversifying content of fruit phytonutrients by transgenic and non-transgenic approaches. The tomato high pigment (hp) mutations exemplify the latter alternative and due to their positive effect on fruit lycopene content, they were introgressed into elite tomato germplasm for cost effective extraction of this important carotenoid. Interestingly, hp mutant fruits are also characterized by higher fruit levels of other functional metabolites, phenotypes caused by mutations in central genes regulating light signal-transduction. This gene identification suggests that modulation of light signaling machinery in plants may be highly effective towards manipulation of fruit phytonutrients but has never been thoroughly reviewed. This review therefore summarizes the progress which has been made on this valuable approach, emphasizing the consequences of transgenic modulation of light signaling components on the functional properties of the tomato fruit.

  9. Rheology and Relaxation Timescales of ABA Triblock Polymer Gels

    NASA Astrophysics Data System (ADS)

    Peters, Andrew; Lodge, Timothy

    When dissolved in a midblock selective solvent, ABA polymers form gels composed of aggregated end block micelles bridged by the midblocks. While much effort has been devoted to the study of the structure of these systems, the dynamics of these systems has received less attention. We examine the underlying mechanism of shear relaxation of ABA triblock polymer gels, especially as a function of chain length, composition, and concentration. Recent work using time-resolved small-angle neutron scattering of polystyrene (PS)-block-poly(ethylene-alt-propylene) (PEP) in squalane has elucidated many aspects of the dynamics of diblock chain exchange. By using rheology to study bulk relaxation phenomena of the triblock equivalent, PS-PEP-PS, we apply the knowledge gained from the chain exchange studies to bridge the gap between the molecular and macroscopic relaxation phenomena in PS-PEP-PS triblock gels.

  10. Three redundant brassinosteroid early response genes encode putative bHLH transcription factors required for normal growth.

    PubMed Central

    Friedrichsen, Danielle M; Nemhauser, Jennifer; Muramitsu, Takamichi; Maloof, Julin N; Alonso, José; Ecker, Joseph R; Furuya, Masaki; Chory, Joanne

    2002-01-01

    Brassinosteroids (BRs) are a class of polyhydroxylated steroids that are important regulators of plant growth and development. We have identified three closely related basic helix-loop-helix (bHLH) transcription factors, BEE1, BEE2, and BEE3, as products of early response genes required for full BR response. Comparison of the phenotypes of plants that overexpress BEE1 with bee1 bee2 bee3 triple-knockout mutant plants suggests that BEE1, BEE2, and BEE3 are functionally redundant positive regulators of BR signaling. Expression of BEE1, BEE2, and BEE3 is also regulated by other hormones, notably abscisic acid (ABA), a known antagonist of BR signaling. Reduced ABA response in plants overexpressing BEE1 suggests that BEE proteins may function as signaling intermediates in multiple pathways. PMID:12454087

  11. Mutation of SPOTTED LEAF3 (SPL3) impairs abscisic acid-responsive signalling and delays leaf senescence in rice

    PubMed Central

    Wang, Seung-Hyun; Lim, Jung-Hyun; Kim, Sang-Sook; Cho, Sung-Hwan; Yoo, Soo-Cheul; Koh, Hee-Jong; Sakuraba, Yasuhito; Paek, Nam-Chon

    2015-01-01

    Lesion mimic mutants commonly display spontaneous cell death in pre-senescent green leaves under normal conditions, without pathogen attack. Despite molecular and phenotypic characterization of several lesion mimic mutants, the mechanisms of the spontaneous formation of cell death lesions remain largely unknown. Here, the rice lesion mimic mutant spotted leaf3 (spl3) was examined. When grown under a light/dark cycle, the spl3 mutant appeared similar to wild-type at early developmental stages, but lesions gradually appeared in the mature leaves close to heading stage. By contrast, in spl3 mutants grown under continuous light, severe cell death lesions formed in developing leaves, even at the seedling stage. Histochemical analysis showed that hydrogen peroxide accumulated in the mutant, likely causing the cell death phenotype. By map-based cloning and complementation, it was shown that a 1-bp deletion in the first exon of Oryza sativa Mitogen-Activated Protein Kinase Kinase Kinase1 (OsMAPKKK1)/OsEDR1/OsACDR1 causes the spl3 mutant phenotype. The spl3 mutant was found to be insensitive to abscisic acid (ABA), showing normal root growth in ABA-containing media and delayed leaf yellowing during dark-induced and natural senescence. Expression of ABA signalling-associated genes was also less responsive to ABA treatment in the mutant. Furthermore, the spl3 mutant had lower transcript levels and activities of catalases, which scavenge hydrogen peroxide, probably due to impairment of ABA-responsive signalling. Finally, a possible molecular mechanism of lesion formation in the mature leaves of spl3 mutant is discussed. PMID:26276867

  12. RANK ligand signaling modulates the matrix metalloproteinase-9 gene expression during osteoclast differentiation

    SciTech Connect

    Sundaram, Kumaran; Nishimura, Riko; Senn, Joseph; Youssef, Rimon F.; London, Steven D.; Reddy, Sakamuri V. . E-mail: reddysv@musc.edu

    2007-01-01

    Osteoclast differentiation is tightly regulated by receptor activator of NF-{kappa}B ligand (RANKL) signaling. Matrix metalloproteinase-9 (MMP-9), a type IV collagenase is highly expressed in osteoclast cells and plays an important role in degradation of extracellular matrix; however, the molecular mechanisms that regulate MMP-9 gene expression are unknown. In this study, we demonstrate that RANKL signaling induces MMP-9 gene expression in osteoclast precursor cells. We further show that RANKL regulates MMP-9 gene expression through TRAF6 but not TRAF2. Interestingly, blockade of p38 MAPK activity by pharmacological inhibitor, SB203580 increases MMP-9 activity whereas ERK1/2 inhibitor, PD98059 decreases RANKL induced MMP-9 activity in RAW264.7 cells. These data suggest that RANKL differentially regulates MMP-9 expression through p38 and ERK signaling pathways during osteoclast differentiation. Transient expression of MMP-9 gene (+ 1 to - 1174 bp relative to ATG start codon) promoter-luciferase reporter plasmids in RAW264.7 cells and RANKL stimulation showed significant increase (20-fold) of MMP-9 gene promoter activity; however, there is no significant change with respect to + 1 bp to - 446 bp promoter region and empty vector transfected cells. These results indicated that MMP-9 promoter sequence from - 446 bp to - 1174 bp relative to start codon is responsive to RANKL stimulation. Sequence analysis of the mouse MMP-9 gene promoter region further identified the presence of binding motif (- 1123 bp to - 1153 bp) for the nuclear factor of activated T cells 1 (NFATc1) transcription factor. Inhibition of NFATc1 using siRNA and VIVIT peptide inhibitor significantly decreased RANKL stimulation of MMP-9 activity. We further confirm by oligonucleotide pull-down assay that RANKL stimuli enhanced NFATc1 binding to MMP-9 gene promoter element. In addition, over-expression of constitutively active NFAT in RAW264.7 cells markedly increased (5-fold) MMP-9 gene promoter activity

  13. Signal-dependent regulation of the sea urchin skeletogenic gene regulatory network.

    PubMed

    Sun, Zhongling; Ettensohn, Charles A

    2014-11-01

    The endoskeleton of the sea urchin embryo is produced by primary mesenchyme cells (PMCs). Maternal inputs activate a complex gene regulatory network (GRN) in the PMC lineage in a cell-autonomous fashion during early development, initially creating a uniform population of prospective skeleton-forming cells. Previous studies showed that at post-blastula stages of development, several effector genes in the network exhibit non-uniform patterns of expression, suggesting that their regulation becomes subject to local, extrinsic cues. Other studies have identified the VEGF and MAPK pathways as regulators of PMC migration, gene expression, and biomineralization. In this study, we used whole mount in situ hybridization (WMISH) to examine the spatial expression patterns of 39 PMC-specific/enriched mRNAs in Strongylocentrotus purpuratus embryos at the late gastrula, early prism and pluteus stages. We found that all 39 mRNAs (including several regulatory genes) showed non-uniform patterns of expression within the PMC syncytium, revealing a global shift in the regulation of the skeletogenic GRN from a cell-autonomous to a signal-dependent mode. In general, localized regions of elevated gene expression corresponded to sites of rapid biomineral deposition. We used a VEGFR inhibitor (axitinib) and a MEK inhibitor (U0126) to show that VEGF signaling and the MAPK pathway are essential for maintaining high levels of gene expression in PMCs at the tips of rods that extend from the ventral region of the embryo. These inhibitors affected gene expression in the PMCs in similar ways, suggesting that VEGF acts via the MAPK pathway. In contrast, axitinib and U0126 did not affect the localized expression of genes in PMCs at the tips of the body rods, which form on the dorsal side of the embryo. Our results therefore indicate that multiple signaling pathways regulate the skeletogenic GRN during late stages of embryogenesis-VEGF/MAPK signaling on the ventral side and a separate, unidentified

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

    PubMed

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

    2008-05-01

    Using pharmacological and biochemical approaches, the signaling pathways between hydrogen peroxide (H(2)O(2)), calcium (Ca(2+))-calmodulin (CaM), and nitric oxide (NO) in abscisic acid (ABA)-induced antioxidant defense were investigated in leaves of maize (Zea mays L.) plants. Treatments with ABA, H(2)O(2), and CaCl(2) induced increases in the generation of NO in maize mesophyll cells and the activity of nitric oxide synthase (NOS) in the cytosolic and microsomal fractions of maize leaves. However, such increases were blocked by the pretreatments with Ca(2+) inhibitors and CaM antagonists. Meanwhile, pretreatments with two NOS inhibitors also suppressed the Ca(2+)-induced increase in the production of NO. On the other hand, treatments with ABA and the NO donor sodium nitroprusside (SNP) also led to increases in the concentration of cytosolic Ca(2+) in protoplasts of mesophyll cells and in the expression of calmodulin 1 (CaM1) gene and the contents of CaM in leaves of maize plants, and the increases induced by ABA were reduced by the pretreatments with a NO scavenger and a NOS inhibitor. Moreover, SNP-induced increases in the expression of the antioxidant genes superoxide dismutase 4 (SOD4), cytosolic ascorbate peroxidase (cAPX), and glutathione reductase 1 (GR1) and the activities of the chloroplastic and cytosolic antioxidant enzymes were arrested by the pretreatments with Ca(2+) inhibitors and CaM antagonists. Our results suggest that Ca(2+)-CaM functions both upstream and downstream of NO production, which is mainly from NOS, in ABA- and H(2)O(2)-induced antioxidant defense in leaves of maize plants.

  15. A STRESS-RESPONSIVE NAC1-Regulated Protein Phosphatase Gene Rice Protein Phosphatase18 Modulates Drought and Oxidative Stress Tolerance through Abscisic Acid-Independent Reactive Oxygen Species Scavenging in Rice1[W][OPEN

    PubMed Central

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

    2014-01-01

    Plants respond to abiotic stresses through a complexity of signaling pathways, and the dephosphorylation mediated by protein phosphatase (PP) is an important event in this process. We identified a rice (Oryza sativa) PP2C gene, OsPP18, as a STRESS-RESPONSIVE NAC1 (SNAC1)-regulated downstream gene. The ospp18 mutant was more sensitive than wild-type plants to drought stress at both the seedling and panicle development stages. Rice plants with OsPP18 suppressed through artificial microRNA were also hypersensitive to drought stress. Microarray analysis of the mutant revealed that genes encoding reactive oxygen species (ROS) scavenging enzymes were down-regulated in the ospp18 mutant, and the mutant exhibited reduced activities of ROS scavenging enzymes and increased sensitivity to oxidative stresses. Overexpression of OsPP18 in rice led to enhanced osmotic and oxidative stress tolerance. The expression of OsPP18 was induced by drought stress but not induced by abscisic acid (ABA). Although OsPP18 is a typical PP2C with enzymatic activity, it did not interact with SNF1-RELATED PROTEIN KINASE2 protein kinases, which function in ABA signaling. Meanwhile, the expression of ABA-responsive genes was not affected in the ospp18 mutant, and the ABA sensitivities of the ospp18 mutant and OsPP18-overexpressing plants were also not altered. Together, these findings suggest that OsPP18 is a unique PP2C gene that is regulated by SNAC1 and confers drought and oxidative stress tolerance by regulating ROS homeostasis through ABA-independent pathways. PMID:25318938

  16. Molecular character of a phosphatase 2C (PP2C) gene relation to stress tolerance in Arabidopsis thaliana.

    PubMed

    Zhang, Jihong; Li, Xiushan; He, Zhimin; Zhao, Xiaoying; Wang, Qiming; Zhou, Bo; Yu, Dashi; Huang, Xinqun; Tang, Dongying; Guo, Xinhong; Liu, Xuanming

    2013-03-01

    Protein phosphatases type 2C (PP2Cs) from group A, which includes the ABI1/HAB1 and PP2CA branches, are key negative regulators of ABA signaling. HAI-1 gene had been shown to affect both seed and vegetative responses to ABA, which is one of PP2Cs clade A in Arabidopsis thaliana. Transgenic plants containing pHAI-1::GUS (β-glucuronidase) displayed GUS activity existing in the vascular system of leave veins, stems and petioles. Green fluorescent protein fused HAI-1 (HAI-1-GFP) was found in the nucleus through transient transformation assays with onion epidermal cells. The water-loss assays indicated the loss-of-function mutants did not show symptoms of wilting and they had still turgid green rosette leaves. The assays of seed germination by exogenous ABA and NaCl manifested that the loss-of-function mutants displayed higher insensitivity than wild-type plants. Taken together, the final results suggest that the HAI-1 (AT5G59220) encoded a nuclear protein and it can be highly induced by ABA and wound in Arabidposis, the stress-tolerance phenotype showed a slightly improvement when HAI-1 gene was disrupted.

  17. Nucleotide diversity patterns of local adaptation at drought-related candidate genes in wild tomatoes.

    PubMed

    Xia, Hui; Camus-Kulandaivelu, Létizia; Stephan, Wolfgang; Tellier, Aurélien; Zhang, Zhenwen

    2010-10-01

    We surveyed nucleotide diversity at two candidate genes LeNCED1 and pLC30-15, involved in an ABA (abscisic acid) signalling pathway, in two closely related tomato species Solanum peruvianum and Solanum chilense. Our six population samples (three for each species) cover a range of mesic to very dry habitats. The ABA pathway plays an important role in the plants' response to drought stress. LeNCED1 is an upstream gene involved in ABA biosynthesis, and pLC30-15 is a dehydrin gene positioned downstream in the pathway. The two genes show very different patterns of nucleotide variation. LeNCED1 exhibits very low nucleotide diversity relative to the eight neutral reference loci that were previously surveyed in these populations. This suggests that strong purifying selection has been acting on this gene. In contrast, pLC30-15 exhibits higher levels of nucleotide diversity and, in particular in S. chilense, higher genetic differentiation between populations than the reference loci, which is indicative of local adaptation. In the more drought-tolerant species S. chilense, one population (from Quicacha) shows a significant haplotype structure, which appears to be the result of positive (diversifying) selection.

  18. [Accumulation of ABA and ODAP in Lathyrus sativus under water stress].

    PubMed

    Xing, G; Zhou, G; Li, Z; Cui, K

    2000-10-01

    The roots of fifteen days old Lathyrus sativus seedlings were treated by PEG, PEG + ABA and ABA, and their leaves were sampled to determine the contents of endogenic ABA, ODAP, MDA and H2O2 and the activity of superoxide dismutase, catalase, peroxidase and glutathione reductase. The results showed that after treated, the contents of ABA and ODAP in leaves increased markedly. The addition of exogenous ABA decreased the increment of MDA and H2O2 contents and retarded the attenuation of CAT activity, which were induced by PEG stress, and enhanced the GR activity. In addition, when materials were treated with exogenous ABA in a long time, the ABA content in leaves was increased markedly, and ODAP was then accumulated. There was no significant effect on metabolism of active oxygen in the early days(0-3 days) of ABA treatment, but the activities of SOD, POD, CAT and GR decreased, and the contents of MDA and H2O2 increased in leaves of Lathyrus sativus with the duration of ABA treatment(7-15 days). The results indicated that ABA could promote the accumulation of ODAP in leaves of Lathyrus sativus.

  19. Along signal paths: an empirical gene set approach exploiting pathway topology

    PubMed Central

    Martini, Paolo; Sales, Gabriele; Massa, M. Sofia; Chiogna, Monica; Romualdi, Chiara

    2013-01-01

    Gene set analysis using biological pathways has become a widely used statistical approach for gene expression analysis. A biological pathway can be represented through a graph where genes and their interactions are, respectively, nodes and edges of the graph. From a biological point of view only some portions of a pathway are expected to be altered; however, few methods using pathway topology have been proposed and none of them tries to identify the signal paths, within a pathway, mostly involved in the biological problem. Here, we present a novel algorithm for pathway analysis clipper, that tries to fill in this gap. clipper implements a two-step empirical approach based on the exploitation of graph decomposition into a junction tree to reconstruct the most relevant signal path. In the first step clipper selects significant pathways according to statistical tests on the means and the concentration matrices of the graphs derived from pathway topologies. Then, it identifies within these pathways the signal paths having the greatest association with a specific phenotype. We test our approach on simulated and two real expression datasets. Our results demonstrate the efficacy of clipper in the identification of signal transduction paths totally coherent with the biological problem. PMID:23002139

  20. Regulation of circadian gene expression in liver by systemic signals and hepatocyte oscillators.

    PubMed

    Kornmann, B; Schaad, O; Reinke, H; Saini, C; Schibler, U

    2007-01-01

    The mammalian circadian timing system has a hierarchical structure, in that a master pacemaker located in the suprachiasmatic nuclei (SCN) coordinates slave oscillators present in virtually all body cells. In both the SCN and peripheral organs, the rhythm-generating oscillators are self-sustained and cell-autonomous, and it is likely that the molecular makeup of master and slave oscillators is nearly identical. However, due to variations in period length, the phase coherence between peripheral oscillators in intact animals must be established by daily signals emanating directly or indirectly from the SCN master clock. The synchronization of individual cellular clocks in peripheral organs is probably accomplished by immediate-early genes that interpret the cyclic systemic signals and convey this phase information to core clock components. This model predicts that circadian gene expression in peripheral organs can be influenced either by systemic signals emanating from the SCN master clock, local oscillators, or both. We developed a transgenic mouse strain in which hepatocyte clocks are only operative when the tetracycline analog doxycycline is added to the food or drinking water. The genome-wide mapping of genes whose cyclic expression in liver does not depend on functional hepatocyte oscillators unveiled putative signaling pathways that may participate in the phase entrainment of peripheral clocks.

  1. Restoration of β -Adrenergic Signaling in Failing Cardiac Ventricular Myocytes via Adenoviral-Mediated Gene Transfer

    NASA Astrophysics Data System (ADS)

    Akhter, Shahab A.; Skaer, Christine A.; Kypson, Alan P.; McDonald, Patricia H.; Peppel, Karsten C.; Glower, Donald D.; Lefkowitz, Robert J.; Koch, Walter J.

    1997-10-01

    Cardiovascular gene therapy is a novel approach to the treatment of diseases such as congestive heart failure (CHF). Gene transfer to the heart would allow for the replacement of defective or missing cellular proteins that may improve cardiac performance. Our laboratory has been focusing on the feasibility of restoring β -adrenergic signaling deficiencies that are a characteristic of chronic CHF. We have now studied isolated ventricular myocytes from rabbits that have been chronically paced to produce hemodynamic failure. We document molecular β -adrenergic signaling defects including down-regulation of myocardial β -adrenergic receptors (β -ARs), functional β -AR uncoupling, and an upregulation of the β -AR kinase (β ARK1). Adenoviral-mediated gene transfer of the human β 2-AR or an inhibitor of β ARK1 to these failing myocytes led to the restoration of β -AR signaling. These results demonstrate that defects present in this critical myocardial signaling pathway can be corrected in vitro using genetic modification and raise the possibility of novel inotropic therapies for CHF including the inhibition of β ARK1 activity in the heart.

  2. Constitutive expression of a peanut ubiquitin-conjugating enzyme gene in Arabidopsis confers improved water-stress tolerance through regulation of stress-responsive gene expression.

    PubMed

    Wan, Xiaorong; Mo, Aiqiong; Liu, Shuai; Yang, Lixia; Li, Ling

    2011-04-01

    Ubiquitin (Ub)-conjugating enzymes (UBCs) are key enzymes involved in ubiquitination. Although UBCs have been shown to play important roles in regulating various aspects of plant growth and development, the role of plant UBCs in abiotic stress response needs to be examined further. Here we report the characterization of a ubiquitin-conjugating enzyme gene AhUBC2 from dehydrated peanut plants. The expression of AhUBC2 gene in peanut plants is responsive to physiological water-stress induced by polyethylene glycol (PEG6000), high salinity, abscisic acid (ABA) or low temperature. The constitutive expression of AhUBC2 gene in wild-type Arabidopsis confers improved tolerance to water-stress induced by sorbitol or soil drought in 35S::AhUBC2 transgenic plants. Constitutive expression of AhUBC2 results in significantly increased expressions of three stress-responsive genes P5CS1, RD29A and KIN1 in 35S::AhUBC2 Arabidopsis grown under normal conditions, whereas the expressions of other four stress-responsive genes NCED3, ABF3, RD29B and RD22 are not affected. The proline level in 35S::AhUBC2 Arabidopsis is significantly higher than that in wild-type Arabidopsis under both soil-drought stressed and control conditions. In contrast, there is no significant difference in the levels of NCED3 transcript and endogenous ABA between wild-type and 35S::AhUBC2 Arabidopsis. These results suggest that constitutive expression of AhUBC2 in Arabidopsis confers improved water-stress tolerance likely through activating an ABA-independent signaling pathway, including regulating the expression of ABA-independent stress-responsive genes and promoting the synthesis of osmolyte proline to protect plants from water deficit.

  3. Targeting Calcium Signaling Induces Epigenetic Reactivation of Tumor Suppressor Genes in Cancer.

    PubMed

    Raynal, Noël J-M; Lee, Justin T; Wang, Youjun; Beaudry, Annie; Madireddi, Priyanka; Garriga, Judith; Malouf, Gabriel G; Dumont, Sarah; Dettman, Elisha J; Gharibyan, Vazganush; Ahmed, Saira; Chung, Woonbok; Childers, Wayne E; Abou-Gharbia, Magid; Henry, Ryan A; Andrews, Andrew J; Jelinek, Jaroslav; Cui, Ying; Baylin, Stephen B; Gill, Donald L; Issa, Jean-Pierre J

    2016-03-15

    Targeting epigenetic pathways is a promising approach for cancer therapy. Here, we report on the unexpected finding that targeting calcium signaling can reverse epigenetic silencing of tumor suppressor genes (TSG). In a screen for drugs that reactivate silenced gene expression in colon cancer cells, we found three classical epigenetic targeted drugs (DNA methylation and histone deacetylase inhibitors) and 11 other drugs that induced methylated and silenced CpG island promoters driving a reporter gene (GFP) as well as endogenous TSGs in multiple cancer cell lines. These newly identified drugs, most prominently cardiac glycosides, did not change DNA methylation locally or histone modifications globally. Instead, all 11 drugs altered calcium signaling and triggered calcium-calmodulin kinase (CamK) activity, leading to MeCP2 nuclear exclusion. Blocking CamK activity abolished gene reactivation and cancer cell killing by these drugs, showing that triggering calcium fluxes is an essential component of their epigenetic mechanism of action. Our data identify calcium signaling as a new pathway that can be targeted to reactivate TSGs in cancer.

  4. Environmental control of plant nuclear gene expression by chloroplast redox signals

    PubMed Central

    Pfalz, Jeannette; Liebers, Monique; Hirth, Matthias; Grübler, Björn; Holtzegel, Ute; Schröter, Yvonne; Dietzel, Lars; Pfannschmidt, Thomas

    2012-01-01

    Plant photosynthesis takes place in specialized cell organelles, the chloroplasts, which perform all essential steps of this process. The proteins involved in photosynthesis are encoded by genes located on the plastid and nuclear genomes. Proper function and regulation of light harvesting and energy fixation thus requires a tight coordination of the gene expression machineries in the two genetic compartments. This is achieved by a bi-directional exchange of information between nucleus and plastids. Signals emerging from plastids report the functional and developmental state of the organelle to the nucleus and initiate distinct nuclear gene expression profiles, which trigger responses that support or improve plastid functions. Recent research indicated that this signaling is absolutely essential for plant growth and development. Reduction/oxidation (redox) signals from photosynthesis are key players in this information network since they do report functional disturbances in photosynthesis, the primary energy source of plants. Such disturbances are caused by environmental fluctuations for instance in illumination, temperature, or water availability. These environmental changes affect the linear electron flow of photosynthesis and result in changes of the redox state of the components involved [e.g., the plastoquinone (PQ) pool] or coupled to it (e.g., the thioredoxin pool). Thus, the changes in redox state directly reflect the environmental impact and serve as immediate plastidial signals to the nucleus. The triggered responses range from counterbalancing reactions within the physiological range up to severe stress responses including cell death. This review focuses on physiological redox signals from photosynthetic electron transport (PET), their relation to the environment, potential transduction pathways to the nucleus and their impact on nuclear gene expression. PMID:23181068

  5. Involvement of Arabidopsis histone acetyltransferase HAC family genes in the ethylene signaling pathway.

    PubMed

    Li, Chao; Xu, Jiang; Li, Jian; Li, Qingyun; Yang, Hongchun

    2014-02-01

    Epigenetic modifications play a fundamental role in regulating chromatin dynamics and gene expression. The level of histone acetylation is controlled by two functionally antagonistic enzymes, namely histone acetyltransferase (HAT) and histone deacetylase (HDAC). CREB-binding protein (CBP)/p300 proteins, a subfamily of highly conserved HATs, are involved in various physiological events including proliferation, differentiation and apoptosis. In this work, we study the poorly known function of their homologous genes, the HAC genes, in Arabidopsis. We found that hac1-involved mutants displayed pleiotropic phenotypes, in particular hypersensitivity to ethylene both in the dark and in the light. We also found that the transcriptional levels of ethylene-responsive genes are significantly higher in the hac1hac5 double mutant than in wild-type plants. Moreover, an ethylene synthesis inhibitor cannot release the triple responses of hac mutants. These results suggest that HACs are involved in the ethylene signaling pathway.

  6. Notch-Nrf2 Axis: Regulation of Nrf2 Gene Expression and Cytoprotection by Notch Signaling

    PubMed Central

    Skoko, John J.; Chartoumpekis, Dionysios V.; Kimura, Shoko; Slocum, Stephen L.; Noda, Kentaro; Palliyaguru, Dushani L.; Fujimuro, Masahiro; Boley, Patricia A.; Tanaka, Yugo; Shigemura, Norihisa; Biswal, Shyam; Yamamoto, Masayuki; Kensler, Thomas W.

    2014-01-01

    The Notch signaling pathway enables regulation and control of development, differentiation, and homeostasis through cell-cell communication. Our investigation shows that Notch signaling directly activates the Nrf2 stress adaptive response pathway through recruitment of the Notch intracellular domain (NICD) transcriptosome to a conserved Rbpjκ site in the promoter of Nrf2. Stimulation of Notch signaling through Notch ligand expression in cells and by overexpression of the NICD in RosaNICD/−::AlbCre mice in vivo induces expression of Nrf2 and its target genes. Continuous and transient NICD expression in the liver produces a Notch-dependent cytoprotective response through direct transcriptional activation of Nrf2 signaling to rescue mice from acute acetaminophen toxicity. This response can be reversed upon genetic disruption of Nrf2. Morphological studies showed that the characteristic phenotype of high-density intrahepatic bile ducts and enlarged liver in RosaNICD/−::AlbCre mice could be at least partially reversed after Nrf2 disruption. Furthermore, the liver and bile duct phenotypes could be recapitulated with constitutive activation of Nrf2 signaling in Keap1F/F::AlbCre mice. It appears that Notch-to-Nrf2 signaling is another important determinant in liver development and function and promotes cell-cell cytoprotective signaling responses. PMID:24298019

  7. Glucocorticoids regulate arrestin gene expression and redirect the signaling profile of G protein-coupled receptors.

    PubMed

    Oakley, Robert H; Revollo, Javier; Cidlowski, John A

    2012-10-23

    G protein-coupled receptors (GPCRs) compose the largest family of cell surface receptors and are the most common target of therapeutic drugs. The nonvisual arrestins, β-arrestin-1 and β-arrestin-2, are multifunctional scaffolding proteins that play critical roles in GPCR signaling. On binding of activated GPCRs at the plasma membrane, β-arrestins terminate G protein-dependent responses (desensitization) and stimulate β-arrestin-dependent signaling pathways. Alterations in the cellular complement of β-arrestin-1 and β-arrestin-2 occur in many human diseases, and their genetic ablation in mice has severe consequences. Surprisingly, however, the factors that control β-arrestin gene expression are poorly understood. We demonstrate that glucocorticoids differentially regulate β-arrestin-1 and β-arrestin-2 gene expression in multiple cell types. Glucocorticoids act via the glucocorticoid receptor (GR) to induce the synthesis of β-arrestin-1 and repress the expression of β-arrestin-2. Glucocorticoid-dependent regulation involves the recruitment of ligand-activated glucocorticoid receptors to conserved and functional glucocorticoid response elements in intron-1 of the β-arrestin-1 gene and intron-11 of the β-arrestin-2 gene. In human lung adenocarcinoma cells, the increased expression of β-arrestin-1 after glucocorticoid treatment impairs G protein-dependent activation of inositol phosphate signaling while enhancing β-arrestin-1-dependent stimulation of the MAPK pathway by protease activated receptor 1. These studies demonstrate that glucocorticoids redirect the signaling profile of GPCRs via alterations in β-arrestin gene expression, revealing a paradigm for cross-talk between nuclear and cell surface receptors and a mechanism by which glucocorticoids alter the clinical efficacy of GPCR-based drugs.

  8. Characterization of genes involved in cytokinin signaling and metabolism from rice.

    PubMed

    Tsai, Yu-Chang; Weir, Nicholas R; Hill, Kristine; Zhang, Wenjing; Kim, Hyo Jung; Shiu, Shin-Han; Schaller, G Eric; Kieber, Joseph J

    2012-04-01

    Two-component signaling elements play important roles in plants, including a central role in cytokinin signaling. We characterized two-component elements from the monocot rice (Oryza sativa) using several complementary approaches. Phylogenetic analysis reveals relatively simple orthologous relationships among the histidine kinases in rice and Arabidopsis (Arabidopsis thaliana). In contrast, the histidine-containing phosphotransfer proteins (OsHPs) and response regulators (OsRRs) display a higher degree of lineage-specific expansion. The intracellular localizations of several OsHPs and OsRRs were examined in rice and generally found to correspond to the localizations of their dicot counterparts. The functionality of rice type-B OsRRs was tested in Arabidopsis; one from a clade composed of both monocot and dicot type-B OsRRs complemented an Arabidopsis type-B response regulator mutant, but a type-B OsRR from a monocot-specific subfamily generally did not. The expression of genes encoding two-component elements and proteins involved in cytokinin biosynthesis and degradation was analyzed in rice roots and shoots and in response to phytohormones. Nearly all type-A OsRRs and OsHK4 were up-regulated in response to cytokinin, but other cytokinin signaling elements were not appreciably affected. Furthermore, multiple cytokinin oxidase (OsCKX) genes were up-regulated by cytokinin. Abscisic acid treatment decreased the expression of several genes involved in cytokinin biosynthesis and degradation. Auxin affected the expression of a few genes; brassinosteroid and gibberellin had only modest effects. Our results support a shared role for two-component elements in mediating cytokinin signaling in monocots and dicots and reveal how phytohormones can impact cytokinin function through modulating gene expression.

  9. High variability of expression profiles of homeologous genes for Wnt, Hh, Notch, and Hippo signaling pathways in Xenopus laevis.

    PubMed

    Michiue, Tatsuo; Yamamoto, Takayoshi; Yasuoka, Yuuri; Goto, Toshiyasu; Ikeda, Takafumi; Nagura, Kei; Nakayama, Takuya; Taira, Masanori; Kinoshita, Tsutomu

    2017-01-12

    Cell signaling pathways, such as Wnt, Hedgehog (Hh), Notch, and Hippo, are essential for embryogenesis, organogenesis, and tissue homeostasis. In this study, we analyzed 415 genes involved in these pathways in the allotetraploid frog, Xenopus laevis. Most genes are retained in two subgenomes called L and S (193 homeologous gene pairs and 29 singletons). This conservation rate of homeologs is much higher than that of all genes in the X. laevis genome (86.9% vs 60.2%). Among singletons, 24 genes are retained in the L subgenome, a rate similar to the average for all genes (82.8% vs 74.6%). In addition, as general components of signal transduction, we also analyzed 32 heparan sulfate proteoglycan (HSPG)-related genes and eight TLE/Groucho transcriptional corepressors-related genes. In these gene sets, all homeologous pairs have been retained. Transcriptome analysis using RNA-seq data from developmental stages and adult tissues demonstrated that most homeologous pairs of signaling components have variable expression patterns, in contrast to the conservative expression profiles of homeologs for transcription factors. Our results indicate that homeologous gene pairs for cell signaling regulation have tended to become subfunctionalized after allotetraploidization. Diversification of signaling pathways by subfunctionalization of homeologs may enhance environmental adaptability. These results provide insights into the evolution of signaling pathways after polyploidization.

  10. Novel transcript nort is a downstream target gene of the Notch signaling pathway in zebrafish.

    PubMed

    Tsutsumi, Makiko; Itoh, Motoyuki

    2007-01-01

    The Notch signaling pathway plays important roles in the regulation of diverse developmental processes. Although many Notch-signal target genes with different specificities have been identified, their regulation and functions are not fully understood. Here, we conducted a microarray screen to search for novel downstream target genes of the Notch pathway in zebrafish. From the screen, we isolated nort (Notch-regulated transcript) as a transcript whose expression was reduced by the inhibition of Notch signaling. The expression level of nort increased when Notch signaling was activated. nort was expressed in hypoblast cells and the developing nervous system. We found its expression pattern to be similar to that of her4, but it showed some differences, at least in the anterior and posterior neural plate at the 3-somite stage. The nort transcript did not contain any long open-reading frame (ORF) of more than 300 nt, and its ORF-encoded sequence showed no significant homology with the proteins in databases. However, nort has one SPS (suppressor of hairless paired binding site) in its 5'-flanking region. These data suggest that nort is a putative noncoding RNA regulated by Notch signaling.

  11. IL-7 signalling represses Bcl-6 and the TFH gene program.

    PubMed

    McDonald, Paul W; Read, Kaitlin A; Baker, Chandra E; Anderson, Ashlyn E; Powell, Michael D; Ballesteros-Tato, André; Oestreich, Kenneth J

    2016-01-08

    The transcriptional repressor Bcl-6 is linked to the development of both CD4(+) T follicular helper (TFH) and central memory T (TCM) cells. Here, we demonstrate that in response to decreased IL-2 signalling, T helper 1 (TH1) cells upregulate Bcl-6 and co-initiate TFH- and TCM-like gene programs, including expression of the cytokine receptors IL-6Rα and IL-7R. Exposure of this potentially bi-potent cell population to IL-6 favours the TFH gene program, whereas IL-7 signalling represses TFH-associated genes including Bcl6 and Cxcr5, but not the TCM-related genes Klf2 and Sell. Mechanistically, IL-7-dependent activation of STAT5 contributes to Bcl-6 repression. Importantly, antigen-specific IL-6Rα(+)IL-7R(+) CD4(+) T cells emerge from the effector population at late time points post influenza infection. These data support a novel role for IL-7 in the repression of the TFH gene program and evoke a divergent regulatory mechanism by which post-effector TH1 cells may contribute to long-term cell-mediated and humoral immunity.

  12. ROCK signalling induced gene expression changes in mouse pancreatic ductal adenocarcinoma cells

    PubMed Central

    Rath, Nicola; Kalna, Gabriela; Clark, William; Olson, Michael F.

    2016-01-01

    The RhoA and RhoC GTPases act via the ROCK1 and ROCK2 kinases to promote actomyosin contraction, resulting in directly induced changes in cytoskeleton structures and altered gene transcription via several possible indirect routes. Elevated activation of the Rho/ROCK pathway has been reported in several diseases and pathological conditions, including disorders of the central nervous system, cardiovascular dysfunctions and cancer. To determine how increased ROCK signalling affected gene expression in pancreatic ductal adenocarcinoma (PDAC) cells, we transduced mouse PDAC cell lines with retroviral constructs encoding fusion proteins that enable conditional activation of ROCK1 or ROCK2, and subsequently performed RNA sequencing (RNA-Seq) using the Illumina NextSeq 500 platform. We describe how gene expression datasets were generated and validated by comparing data obtained by RNA-Seq with RT-qPCR results. Activation of ROCK1 or ROCK2 signalling induced significant changes in gene expression that could be used to determine how actomyosin contractility influences gene transcription in pancreatic cancer. PMID:27824338

  13. Monitoring Cellular Phosphorylation Signaling Pathways into Chromatin and Down to the Gene Level*

    PubMed Central

    Han, Yumiao; Yuan, Zuo-Fei; Molden, Rosalynn C.; Garcia, Benjamin A.

    2016-01-01

    Protein phosphorylation, one of the most common and important modifications of acute and reversible regulation of protein function, plays a dominant role in almost all cellular processes. These signaling events regulate cellular responses, including proliferation, differentiation, metabolism, survival, and apoptosis. Several studies have been successfully used to identify phosphorylated proteins and dynamic changes in phosphorylation status after stimulation. Nevertheless, it is still rather difficult to elucidate precise complex phosphorylation signaling pathways. In particular, how signal transduction pathways directly communicate from the outer cell surface through cytoplasmic space and then directly into chromatin networks to change the transcriptional and epigenetic landscape remains poorly understood. Here, we describe the optimization and comparison of methods based on thiophosphorylation affinity enrichment, which can be utilized to monitor phosphorylation signaling into chromatin by isolation of phosphoprotein containing nucleosomes, a method we term phosphorylation-specific chromatin affinity purification (PS-ChAP). We utilized this PS-ChAP1 approach in combination with quantitative proteomics to identify changes in the phosphorylation status of chromatin-bound proteins on nucleosomes following perturbation of transcriptional processes. We also demonstrate that this method can be employed to map phosphoprotein signaling into chromatin containing nucleosomes through identifying the genes those phosphorylated proteins are found on via thiophosphate PS-ChAP-qPCR. Thus, our results showed that PS-ChAP offers a new strategy for studying cellular signaling and chromatin biology, allowing us to directly and comprehensively investigate phosphorylation signaling into chromatin to investigate if these pathways are involved in altering gene expression. The mass spectrometry proteomics data have been deposited to the ProteomeXchange Consortium with the data set

  14. Proteomic analyses reveal the key roles of BrlA and AbaA in biogenesis of gliotoxin in Aspergillus fumigatus

    SciTech Connect

    Shin, Kwang-Soo; Kim, Young Hwan; Yu, Jae-Hyuk

    2015-07-31

    The opportunistic human pathogenic fungus Aspergillus fumigatus primarily reproduces by forming a large number of asexual spores (conidia). Sequential activation of the central regulators BrlA, AbaA and WetA is necessary for the fungus to undergo asexual development. In this study, to address the presumed roles of these key developmental regulators during proliferation of the fungus, we analyzed and compared the proteomes of vegetative cells of wild type (WT) and individual mutant strains. Approximately 1300 protein spots were detectable from 2-D electrophoresis gels. Among these, 13 proteins exhibiting significantly altered accumulation levels were further identified by ESI-MS/MS. Markedly, we found that the GliM and GliT proteins associated with gliotoxin (GT) biosynthesis and self-protection of the fungus from GT were significantly down-regulated in the ΔabaA and ΔbrlA mutants. Moreover, mRNA levels of other GT biosynthetic genes including gliM, gliP, gliT, and gliZ were significantly reduced in both mutant strains, and no and low levels of GT were detectable in the ΔbrlA and ΔabaA mutant strains, respectively. As GliT is required for the protection of the fungus from GT, growth of the ΔbrlA mutant with reduced levels of GliT was severely impaired by exogenous GT. Our studies demonstrate that AbaA and BrlA positively regulate expression of the GT biosynthetic gene cluster in actively growing vegetative cells, and likely bridge morphological and chemical development during the life-cycle of A. fumigatus. - Highlights: • Proteome analyses of WT and mutants reveal 13 differentially expressed proteins. • The GliT and GliM proteins are significantly down-regulated by ΔabaA and ΔbrlA. • Expression of other gliotoxin biosynthetic genes is lowered by ΔabaA and ΔbrlA. • Growth of ΔbrlA strain lacking GliT is completely inhibited by exogenous gliotoxin. • BrlA and AbaA play key roles in biogenesis of gliotoxin in Aspergillus fumigatus.

  15. Identification of genes and signaling pathways associated with diabetic neuropathy using a weighted correlation network analysis

    PubMed Central

    Li, Ya; Ma, Weiguo; Xie, Chuanqing; Zhang, Min; Yin, Xiaohong; Wang, Fenfen; Xu, Jie; Shi, Bingyin

    2016-01-01

    Abstract Background: The molecular mechanisms behind diabetic neuropathy remains to be investigated. Methods: This is a secondary study on microarray dataset (GSE24290) downloaded from Gene Expression Omnibus (GEO) at the National Center for Biotechnology Information (NCBI), which included 18 nerve tissue samples of progressing diabetic neuropathy (fibers loss ≥500 fibers/mm2) and 17 nerve tissue samples of nonprogressing diabetic neuropathy (fibers loss ≤100 fibers/mm2). Differentially expressed genes (DEGs) were screened between progressing and nonprogressing diabetic neuropathy. With the DEGs obtained, a weighted gene coexpression network analysis was conducted to identify gene clusters associated with diabetic neuropathy. Diabetes-related microRNAs (miRNAs) and their target genes were predicted and mapped to the genes in the gene clusters identified. Consequently, a miRNA–gene network was constructed, for which gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis was performed. Potential drugs for treatment of diabetic neuropathy were also predicted. Results: Total 370 upregulated and 379 downregulated DEGs were screened between nonprogressing and progressing diabetic neuropathy. Has-miR-377, has-miR-216a, and has-miR-217 were associated with diabetes. Inflammation was the most significant GO term. The peroxisome proliferator-activated receptor (PPAR) pathway and the adenosine monophosphate (AMP)-activated protein kinase (AMPK) signaling pathway were significantly KEGG pathways significantly enriched with PPAR gamma (PPARG), stearoyl-CoA desaturase (SCD), cluster of differentiation 36 (CD36), and phosphoenolpyruvate carboxykinase 1 (PCK1). Conclusion: The study suggests that PPARG, SCD, CD36, PCK1, AMPK pathway, and PPAR pathway may be involved in progression of diabetic neuropathy. PMID:27893688

  16. Integral control of plant gravitropism through the interplay of hormone signaling and gene regulation.

    PubMed

    Rodrigo, Guillermo; Jaramillo, Alfonso; Blázquez, Miguel A

    2011-08-17

    The interplay between hormone signaling and gene regulatory networks is instrumental in promoting the development of living organisms. In particular, plants have evolved mechanisms to sense gravity and orient themselves accordingly. Here, we present a mathematical model that reproduces plant gravitropic responses based on known molecular genetic interactions for auxin signaling coupled with a physical description of plant reorientation. The model allows one to analyze the spatiotemporal dynamics of the system, triggered by an auxin gradient that induces differential growth of the plant with respect to the gravity vector. Our model predicts two important features with strong biological implications: 1), robustness of the regulatory circuit as a consequence of integral control; and 2), a higher degree of plasticity generated by the molecular interplay between two classes of hormones. Our model also predicts the ability of gibberellins to modulate the tropic response and supports the integration of the hormonal role at the level of gene regulation.

  17. Heme Signaling Impacts Global Gene Expression, Immunity and Dengue Virus Infectivity in Aedes aegypti

    PubMed Central

    Bottino-Rojas, Vanessa; Talyuli, Octávio A. C.; Jupatanakul, Natapong; Sim, Shuzhen; Dimopoulos, George; Venancio, Thiago M.; Bahia, Ana C.; Sorgine, Marcos H.; Oliveira, Pedro L.; Paiva-Silva, Gabriela O.

    2015-01-01

    Blood-feeding mosquitoes are exposed to high levels of heme, the product of hemoglobin degradation. Heme is a pro-oxidant that influences a variety of cellular processes. We performed a global analysis of heme-regulated Aedes aegypti (yellow fever mosquito) transcriptional changes to better understand influence on mosquito physiology at the molecular level. We observed an iron- and reactive oxygen species (ROS)-independent signaling induced by heme that comprised genes related to redox metabolism. By modulating the abundance of these transcripts, heme possibly acts as a danger signaling molecule. Furthermore, heme triggered critical changes in the expression of energy metabolism and immune response genes, altering the susceptibility towards bacteria and dengue virus. These findings seem to have implications on the adaptation of mosquitoes to hematophagy and consequently on their ability to transmit diseases. Altogether, these results may also contribute to the understanding of heme cell biology in eukaryotic cells. PMID:26275150

  18. SAMP8 mice have altered hippocampal gene expression in long term potentiation, phosphatidylinositol signaling, and endocytosis pathways.

    PubMed

    Armbrecht, Harvey J; Siddiqui, Akbar M; Green, Michael; Farr, Susan A; Kumar, Vijaya B; Banks, William A; Patrick, Ping; Shah, Gul N; Morley, John E

    2014-01-01

    The senescence-accelerated mouse (SAMP8) strain exhibits decreased learning and memory and increased amyloid beta (Aβ) peptide accumulation at 12 months. To detect differences in gene expression in SAMP8 mice, we used a control mouse that was a 50% cross between SAMP8 and CD-1 mice and which showed no memory deficits (50% SAMs). We then compared gene expression in the hippocampus of 4- and 12-month-old SAMP8 and control mice using Affymetrix gene arrays. At 12 months, but not at 4 months, pathway analysis revealed significant differences in the long term potentiation (6 genes), phosphatidylinositol signaling (6 genes), and endocytosis (10 genes) pathways. The changes in long term potentiation included mitogen-activated protein kinase (MAPK) signaling (N-ras, cAMP responsive element binding protein [CREB], protein phosphatase inhibitor 1) and Ca-dependent signaling (inositol triphosphate [ITP] receptors 1 and 2 and phospholipase C). Changes in phosphatidylinositol signaling genes suggested altered signaling through phosphatidylinositol-3-kinase, and Western blotting revealed phosphorylation changes in serine/threonine protein kinase AKT and 70S6K. Changes in the endocytosis pathway involved genes related to clathrin-mediated en