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Sample records for abscisic acid effects

  1. 8[prime]-Methylene Abscisic Acid (An Effective and Persistent Analog of Abscisic Acid).

    PubMed Central

    Abrams, S. R.; Rose, P. A.; Cutler, A. J.; Balsevich, J. J.; Lei, B.; Walker-Simmons, M. K.

    1997-01-01

    We report here the synthesis and biological activity of a new persistent abscisic acid (ABA) analog, 8[prime]-methylene ABA. This ABA analog has one additional carbon atom attached through a double bond to the 8[prime]-carbon of the ABA molecule. (+)-8[prime]-Methylene ABA is more active than the natural hormone (+)-ABA in inhibiting germination of cress seed and excised wheat embryos, in reducing growth of suspension-cultured corn cells, and in reducing transpiration in wheat seedlings. The (+)-8[prime]-methylene analog is slightly weaker than (+)-ABA in increasing expression of ABA-inducible genes in transgenic tobacco, but is equally active in stimulating a transient elevation of the pH of the medium of corn cell cultures. In corn cells, both (+)-ABA and (+)-8[prime]-methylene ABA are oxidized at the 8[prime] position. ABA is oxidized to phaseic acid and (+)-8[prime]-methylene ABA is converted more slowly to two isomeric epoxides. The alteration in the ABA structure causes the analog to be metabolized more slowly than ABA, resulting in longer-lasting and more effective biological activity relative to ABA. PMID:12223691

  2. Abscission: Role of Abscisic Acid

    PubMed Central

    Cracker, L. E.; Abeles, F. B.

    1969-01-01

    The effect of abscisic acid on cotton (Gossypium hirsutum L. cv. Acala 4-42) and bean (Phaseolus vulgaris L. cv. Red Kidney) explants was 2-fold. It increased ethylene production from the explants, which was found to account for some of its ability to accelerate abscission. Absci is acid also increased the activity of cellulase. Increased synthesis of cellulase was not du to an increase in aging of the explants but rather was an effect of abscisic acid on the processes that lead to cellulase synthesis or activity. PMID:16657181

  3. A Kinetic Analysis of the Effects of Gibberellic Acid, Zeatin, and Abscisic Acid on Leaf Tissue Senescence in Rumex1

    PubMed Central

    Manos, Peter J.; Goldthwaite, Jonathan

    1975-01-01

    Hormones which inhibit senescence in Rumex leaf tissue in the dark include gibberellic acid and the cytokinin zeatin. Abscisic acid accelerates senescence in this tissue. Other workers have proposed that cytokinins, but not gibberellins, interact with abscisic acid in senescing Rumex leaf tissue. The present study reinvestigates the question of interaction using measurements of chlorophyll degradation kinetics as parameters of senescence rate and draws the conclusion that neither zeatin nor gibberellic acid interact with abscisic acid in this system. In support of this conclusion are these results. Zeatin clearly cannot overcome the effects of abscisic acid when hormone solutions are replaced every other day. The kinetics of chlorophyll breakdown for tissue treated with unreplaced saturating zeatin solutions is different from that of tissue exposed to saturating zeatin plus abscisic acid. The observed rates of chlorophyll breakdown for tissue treated with abscisic acid and zeatin agree closely with predicted rates using a multiplicative model for independent action of the two hormones. Zeatin solutions, when replaced every other day, show up to a 550-fold increase in effective concentration in the retardation of senescence. Less than a 10-fold increase could be accounted for by the addition of more zeatin molecules to the tissue. A nonbiological inactivation of zeatin or the production of an inhibitor of zeatin action by the tissue could not be demonstrated. It seems that zeatin is metabolically inactivated or sequestered in this tissue. The possible physiological significance of the inactivation of cytokinins in leaf tissue is discussed. PMID:16659049

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

    NASA Technical Reports Server (NTRS)

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

    1988-01-01

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

  6. Exogenous Abscisic Acid and Gibberellic Acid Elicit Opposing Effects on Fusarium graminearum Infection in Wheat.

    PubMed

    Buhrow, Leann M; Cram, Dustin; Tulpan, Dan; Foroud, Nora A; Loewen, Michele C

    2016-09-01

    Although the roles of salicylate (SA) and jasmonic acid (JA) have been well-characterized in Fusarium head blight (FHB)-infected cereals, the roles of other phytohormones remain more ambiguous. Here, the association between an array of phytohormones and FHB pathogenesis in wheat is investigated. Comprehensive profiling of endogenous hormones demonstrated altered cytokinin, gibberellic acid (GA), and JA metabolism in a FHB-resistant cultivar, whereas challenge by Fusarium graminearum increased abscisic acid (ABA), JA, and SA in both FHB-susceptible and -resistant cultivars. Subsequent investigation of ABA or GA coapplication with fungal challenge increased and decreased FHB spread, respectively. These phytohormones-induced effects may be attributed to alteration of the F. graminearum transcriptome because ABA promoted expression of early-infection genes, including hydrolases and cytoskeletal reorganization genes, while GA suppressed nitrogen metabolic gene expression. Neither ABA nor GA elicited significant effects on F. graminearum fungal growth or sporulation in axenic conditions, nor do these phytohormones affect trichothecene gene expression, deoxynivalenol mycotoxin accumulation, or SA/JA biosynthesis in F. graminearum-challenged wheat spikes. Finally, the combined application of GA and paclobutrazol, a Fusarium fungicide, provided additive effects on reducing FHB severity, highlighting the potential for combining fungicidal agents with select phytohormone-related treatments for management of FHB infection in wheat. PMID:27135677

  7. Abscisic Acid Synthesis and Response

    PubMed Central

    Finkelstein, Ruth

    2013-01-01

    Abscisic acid (ABA) is one of the “classical” plant hormones, i.e. discovered at least 50 years ago, that regulates many aspects of plant growth and development. This chapter reviews our current understanding of ABA synthesis, metabolism, transport, and signal transduction, emphasizing knowledge gained from studies of Arabidopsis. A combination of genetic, molecular and biochemical studies has identified nearly all of the enzymes involved in ABA metabolism, almost 200 loci regulating ABA response, and thousands of genes regulated by ABA in various contexts. Some of these regulators are implicated in cross-talk with other developmental, environmental or hormonal signals. Specific details of the ABA signaling mechanisms vary among tissues or developmental stages; these are discussed in the context of ABA effects on seed maturation, germination, seedling growth, vegetative stress responses, stomatal regulation, pathogen response, flowering, and senescence. PMID:24273463

  8. Effect of abscisic acid on the linoleic acid metabolism in developing maize embryos

    SciTech Connect

    Abian, J.; Gelpi, E.; Pages, M. )

    1991-04-01

    Partially purified protein extracts from maize (Zea mays L.) embryos, whether treated or not with abscisic acid (ABA), were incubated with linoleic acid (LA) and 1-({sup 14}C)LA. The resulting LA metabolites were monitored by high performance liquid chromatography with a radioactivity detector and identified by gas chromatography-mass spectrometry. {alpha}- and {gamma}-ketol metabolites arising from 9-lipoxygenase activity were the more abundant compounds detected in the incubates, although the corresponding metabolites produced by 13-lipoxygenase were also present in the samples. In addition, a group of stereoisomers originating form two isomeric trihydroxy acids (9,12,13-trihydroxy-10-octadecenoic and 9,10,13-trihydroxy-11-octadecenoic acids) are described. Important variations in the relative proportions of the LA metabolites were observed depending on the embryo developmental stage and on ABA treatment. Two new ABA-induced compounds have been detected. These compounds are present in embryos at all developmental stages, being more abundant in old (60 days) embryos. Furthermore, ABA induction of these compounds is maximum at very young development stages, decreasing as maturation progresses. A tentative structure for these compounds (10-oxo-9,13-dihydroxy-11-octadecenoic acid and 12-oxo-9,13-dihydroxy-10-octadecenoic acid) is also provided. This study revealed an early stage in maize embryogenesis characterized by a higher relative sensitivity to ABA. The physiological importance of ABA on LA metabolism is discussed.

  9. [Effects of abscisic acid on chemical components content and color of Glycyrrhiza uralensis].

    PubMed

    Xiang, Yu; Liu, Chun-sheng; Liu, Yong; Song, Xiao-na; Gu, Xuan

    2015-05-01

    An experiment was conducted using cultivated Glycyrrhiza uralensis in age of one year to study the effects of abscisic acid (ABA) on chemical components content and color of G. uralensis. By using different concentrations of ABA spraying on leaves, the change of the chemical component content was analyzed within 45 d after ABA stimulation, and the effects on quality were studied combined with colorimetric analysis data. It turned out that in some sense the content of glycyrrhizic acid and liquiritin had increased within 45 d, especially for liquiritin. After high concentrations of ABA (3.96 mg · L(-1)) stimulating, the content of glycyrrhizic acid rose 52% while liquiritin up 392% within 30 d. Then they both showed a decline in the content of glycyrrhizic acid and liquiritin on 45 d. Color index values of a* and b* were all significantly higher than that of the control group within 45 d, which meant the color of powders turned toward red and yellow. The conclusion was that ABA (3.96 mg · L(-1)) stimulating could not only improve the quality in the traditional sense through the color of G. uralensis, but also in the modern sense by improving the content of glycyrrhizic acid and liquiritin. PMID:26323130

  10. Priming effect of abscisic acid on alkaline stress tolerance in rice (Oryza sativa L.) seedlings.

    PubMed

    Wei, Li-Xing; Lv, Bing-Sheng; Wang, Ming-Ming; Ma, Hong-Yuan; Yang, Hao-Yu; Liu, Xiao-Long; Jiang, Chang-Jie; Liang, Zheng-Wei

    2015-05-01

    Saline-alkaline stress is characterized by high salinity and high alkalinity (high pH); alkaline stress has been shown to be the primary factor inhibiting rice seedling growth. In this study, we investigated the potential priming effect of abscisic acid (ABA) on tolerance of rice seedlings to alkaline stress simulated by Na2CO3. Seedlings were pretreated with ABA at concentrations of 0 (control), 10, and 50 μM by root-drench for 24 h and then transferred to a Na2CO3 solution that did not contain ABA. Compared to control treatment, pretreatment with ABA substantially improved the survival rate of rice seedlings and increased biomass accumulation after 7 days under the alkaline condition. ABA application at 10 μM also alleviated the inhibitory effects of alkaline stress on the total root length and root surface area. Physiologically, ABA increased relative water content (RWC) and decreased cell membrane injury degree (MI) and Na(+)/K(+) ratios. In contrast, fluridone (an ABA biosynthesis inhibitor) decreased the RWC and increased MI in shoots under the alkaline conditions. These data suggest that ABA has a potent priming effect on the adaptive response to alkaline stress in rice and may be useful for improving rice growth in saline-alkaline paddy fields. PMID:25780993

  11. The effects of abscisic acid (ABA) addition on cadmium accumulation of two ecotypes of Solanum photeinocarpum.

    PubMed

    Wang, Jin; Lin, Lijin; Luo, Li; Liao, Ming'an; Lv, Xiulan; Wang, Zhihui; Liang, Dong; Xia, Hui; Wang, Xun; Lai, Yunsong; Tang, Yi

    2016-03-01

    The study of the effects of exogenous abscisic acid (ABA) addition on cadmium (Cd) accumulation of two ecotypes (mining and farmland) of Solanum photeinocarpum was operated through a pot experiment. The results showed that the biomass and chlorophyll content of the two ecotypes of S. photeinocarpum increased with increasing ABA concentration. Applying exogenous ABA increased Cd content in the two ecotypes of S. photeinocarpum. The maximum Cd contents in shoots of the two ecotypes of S. photeinocarpum were obtained at 20 μmol/L ABA; shoot Cd contents respectively for the mining and farmland ecotypes were 33.92 and 24.71% higher than those for the control. Applying exogenous ABA also increased Cd extraction by the two ecotypes of S. photeinocarpum, and the highest Cd extraction was obtained at 20 μmol/L ABA with 569.42 μg/plant in shoots of the mining ecotype and 520.51 μg/plant in shoots of the farmland ecotype respectively. Therefore, exogenous ABA can be used for enhancing the Cd extraction ability of S. photeinocarpum, and 20 μmol/L ABA was the optimal dose. PMID:26899030

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

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1984-01-01

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

  14. Transcriptomic insights into antagonistic effects of gibberellin and abscisic acid on petal growth in Gerbera hybrida.

    PubMed

    Li, Lingfei; Zhang, Wenbin; Zhang, Lili; Li, Na; Peng, Jianzong; Wang, Yaqin; Zhong, Chunmei; Yang, Yuping; Sun, Shulan; Liang, Shan; Wang, Xiaojing

    2015-01-01

    Petal growth is central to floral morphogenesis, but the underlying genetic basis of petal growth regulation is yet to be elucidated. In this study, we found that the basal region of the ray floret petals of Gerbera hybrida was the most sensitive to treatment with the phytohormones gibberellin (GA) and abscisic acid (ABA), which regulate cell expansion during petal growth in an antagonistic manner. To screen for differentially expressed genes (DEGs) and key regulators with potentially important roles in petal growth regulation by GA or/and ABA, the RNA-seq technique was employed. Differences in global transcription in petals were observed in response to GA and ABA and target genes antagonistically regulated by the two hormones were identified. Moreover, we also identified the pathways associated with the regulation of petal growth after application of either GA or ABA. Genes relating to the antagonistic GA and ABA regulation of petal growth showed distinct patterns, with genes encoding transcription factors (TFs) being active during the early stage (2 h) of treatment, while genes from the "apoptosis" and "cell wall organization" categories were expressed at later stages (12 h). In summary, we present the first study of global expression patterns of hormone-regulated transcripts in G. hybrida petals; this dataset will be instrumental in revealing the genetic networks that govern petal morphogenesis and provides a new theoretical basis and novel gene resources for ornamental plant breeding. PMID:25852718

  15. Two Transduction Pathways Mediate Rapid Effects of Abscisic Acid in Commelina Guard Cells.

    PubMed Central

    Allan, A. C.; Fricker, M. D.; Ward, J. L.; Beale, M. H.; Trewavas, A. J.

    1994-01-01

    Commelina guard cells can be rapidly closed by abscisic acid (ABA), and it is thought that this signal is always transduced through increases in cytosolic calcium. However, when Commelina plants were grown at 10 to 17[deg]C, most guard cells failed to exhibit any ABA-induced increase in cytosolic calcium even though all of these cells closed. At growth temperatures of 25[deg]C or above, ABA-induced closure was always associated with an increase in cytosolic calcium. This suggests that there may be two transduction routes for ABA in guard cells; only one involves increases in cytosolic calcium. Activation of either pathway on its own appears to be sufficient to cause closure. Because the rates of ABA accumulation and transport in plants grown at different temperatures are likely to be different, we synthesized and microinjected caged ABA directly into guard cells. ABA was released internally by UV photolysis and subsequently caused stomatal closure. This result suggests a possible intracellular locale for the hypothesized ABA receptor. PMID:12244274

  16. Transcriptomic insights into antagonistic effects of gibberellin and abscisic acid on petal growth in Gerbera hybrida

    PubMed Central

    Li, Lingfei; Zhang, Wenbin; Zhang, Lili; Li, Na; Peng, Jianzong; Wang, Yaqin; Zhong, Chunmei; Yang, Yuping; Sun, Shulan; Liang, Shan; Wang, Xiaojing

    2015-01-01

    Petal growth is central to floral morphogenesis, but the underlying genetic basis of petal growth regulation is yet to be elucidated. In this study, we found that the basal region of the ray floret petals of Gerbera hybrida was the most sensitive to treatment with the phytohormones gibberellin (GA) and abscisic acid (ABA), which regulate cell expansion during petal growth in an antagonistic manner. To screen for differentially expressed genes (DEGs) and key regulators with potentially important roles in petal growth regulation by GA or/and ABA, the RNA-seq technique was employed. Differences in global transcription in petals were observed in response to GA and ABA and target genes antagonistically regulated by the two hormones were identified. Moreover, we also identified the pathways associated with the regulation of petal growth after application of either GA or ABA. Genes relating to the antagonistic GA and ABA regulation of petal growth showed distinct patterns, with genes encoding transcription factors (TFs) being active during the early stage (2 h) of treatment, while genes from the “apoptosis” and “cell wall organization” categories were expressed at later stages (12 h). In summary, we present the first study of global expression patterns of hormone-regulated transcripts in G. hybrida petals; this dataset will be instrumental in revealing the genetic networks that govern petal morphogenesis and provides a new theoretical basis and novel gene resources for ornamental plant breeding. PMID:25852718

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

    PubMed

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

    2015-01-01

    The phytohormone abscisic acid (ABA), in addition to regulating physiological functions in plants, is also produced and released by several mammalian cell types, including human granulocytes, where it stimulates innate immune functions via an increase of the intracellular cAMP concentration ([cAMP]i). We synthesized several ABA analogs and evaluated the structure-activity relationship, by the systematical modification of selected regions of these analogs. The resulting molecules were tested for their ability to inhibit the ABA-induced increase of [cAMP]i in human granulocytes. The analogs with modified configurations at C-2' and C-3' abrogated the ABA-induced increase of the [cAMP]i and also inhibited several pro-inflammatory effects induced by exogenous ABA on granulocytes and monocytes. Accordingly, these analogs could be suitable as novel putative anti-inflammatory compounds. PMID:25496807

  18. Effects of norflurazon, an inhibitor of carotenogenesis, on abscisic acid and xanthoxin in the caps of gravistimulated maize roots

    NASA Technical Reports Server (NTRS)

    Feldman, L. J.; Sun, P. S.

    1986-01-01

    Maize seeds were germinated in the dark in the presence of the carotenoid synthesis inhibitor norflurazon and the levels of abscisic acid, xanthoxin and total carotenoids were measured in the root cap and in the adjacent 1.5 mm segment. In norflurazon-treated roots abscisic acid levels were markedly reduced, but an increase occurred in the levels of xanthoxin, a compound structurally and physiologically similar to abscisic acid. In the cultivar of maize (Zea mays L. cv. Merit) used for this work, brief illumination of the root is required for gravitropic curving. Following illumination both control and norflurazon-treated roots showed normal gravitropic curvature; however, the rate of curvature was delayed in norflurazon-treated roots. Our data from norflurazon-treated roots are consistent with a role for xanthoxin in maize root gravitropism. The increase in xanthoxin in the presence of an inhibitor of carotenoid synthesis suggests that xanthoxin and abscisic acid originate, at least in part, via different metabolic pathways.

  19. Abscisic Acid in relation to mineral deprivation.

    PubMed

    Mizrahi, Y; Richmond, A E

    1972-12-01

    Tobacco (Nicotiana rustica) plants growing in half-strength Hoagland solution were deprived of nutrients by being transferred to distilled water. The abscisic acid content of leaves in the mineral-deprived plants rose continuously throughout the 7 days of the experimental period. However, although the content of ABA rose within 24 hours, a decline in growth and leaf-chlorophyll were discernible only after the 4th day of mineral deprivation. As anticipated, mineral-deprived (stressed) plants exhibit "resistance" to lack of aeration in the root medium, similar to that shown in salt-stressed plants or plants that were pretreated with absiscic acid. When the mineral-deprived plants were returned to half-strength Hoagland, the content of leaf abscisic acid declined to the prestressed level and the "resistance" to lack of root aeration disappeared.These results indicate that an increase in abscisic acid may be induced by conditions unfavorable to growth and not exclusively by conditions affecting the plant's water balance. In addition, the work also indicates that mineral deficiency is associated with significant modification in the hormonal balance of the plant. PMID:16658239

  20. 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.

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

    PubMed

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

    2016-01-01

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

  2. Effect of abscisic acid and cold acclimation on the cytoskeletal and phosphorylated proteins in different cultivars of Triticum aestivum L.

    PubMed

    Olinevich, O V; Khokhlova, L P; Raudaskoski, M

    2000-01-01

    In winter wheat, the tubulin and 60 kDa-phosphorylated proteins/actin ratio is considerably higher in the roots than in the leaves. Differences in the content of the main cytoskeletal proteins were also found in the leaves of the different cultivars. It is suggested that the lower amount of the tubulin and 60 kDa-phosphorylated proteins and higher content of actin determine the greater tubulin cytoskeletal stability in the leaves and their higher frost resistance, as compared with the roots. Also, it is possible that the higher content of the tubulin and 60 kDa-phosphorylated proteins defines the lower microtubule (MT) stability in the leaves of the low frost resistant cultivar than in the leaves of the more frost resistant ones. In the roots and leaves of the low frost resistant cultivar, the low stability of the numerous tubulin structures is apparently one reason for the abscisic acid (ABA)-induced reduction of the cytoskeletal and 60 kDa-phosphorylated proteins in the cells. The cold acclimation compensated the ABA effect in the roots of the very frost resistant cultivar in the most extent. This suggests the existence of the different pathways in the increased plant cell frost resistance through the action of ABA and low temperature. PMID:10860572

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

    PubMed Central

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

    2016-01-01

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

  4. Effects of abscisic acid on ethylene biosynthesis and perception in Hibiscus rosa-sinensis L. flower development

    PubMed Central

    Trivellini, Alice; Ferrante, Antonio; Vernieri, Paolo; Serra, Giovanni

    2011-01-01

    The effect of the complex relationship between ethylene and abscisic acid (ABA) on flower development and senescence in Hibiscus rosa-sinensis L. was investigated. Ethylene biosynthetic (HrsACS and HrsACO) and receptor (HrsETR and HrsERS) genes were isolated and their expression evaluated in three different floral tissues (petals, style–stigma plus stamens, and ovaries) of detached buds and open flowers. This was achieved through treatment with 0.1 mM 1-aminocyclopropane-1-carboxylic acid (ACC) solution, 500 nl l−1 methylcyclopropene (1-MCP), and 0.1 mM ABA solution. Treatment with ACC and 1-MCP confirmed that flower senescence in hibiscus is ethylene dependent, and treatment with exogenous ABA suggested that ABA may play a role in this process. The 1-MCP impeded petal in-rolling and decreased ABA content in detached open flowers after 9 h. This was preceded by an earlier and sequential increase in ABA content in 1-MCP-treated petals and style–stigma plus stamens between 1 h and 6 h. ACC treatment markedly accelerated flower senescence and increased ethylene production after 6 h and 9 h, particularly in style–stigma plus stamens. Ethylene evolution was positively correlated in these floral tissues with the induction of the gene expression of ethylene biosynthetic and receptor genes. Finally, ABA negatively affected the ethylene biosynthetic pathway and tissue sensitivity in all flower tissues. Transcript abundance of HrsACS, HrsACO, HrsETR, and HrsERS was reduced by exogenous ABA treatment. This research underlines the regulatory effect of ABA on the ethylene biosynthetic and perception machinery at a physiological and molecular level when inhibitors or promoters of senescence are exogenously applied. PMID:21841180

  5. Effects of abscisic acid and high osmoticum on storage protein gene expression in microspore embryos of Brassica napus

    SciTech Connect

    Wilen, R.W.; Mandel, R.M.; Pharis, R.P.; Moloney, M.M. ); Holbrook, L.A. )

    1990-11-01

    Storage protein gene expression, characteristic of mid- to late embryogenesis, was investigated in microspore embryos of rapeseed (Brassica napus). These embryos, derived from the immature male gametophyte, accumulate little or no detectable napin or cruciferin mRNA when cultured on hormone-free medium containing 13% sucrose. The addition of abscisic acid (ABA) to the medium results in an increase in detectable transcripts encoding both these polypeptides. Storage protein mRNA is induced at 1 micromolar ABA with maximum stimulation occurring between 5 and 50 micromolar. This hormone induction results in a level of storage protein mRNA that is comparable to that observed in zygotic embryos of an equivalent morphological stage. Effects similar to that of ABA are noted when 12.5% sorbitol is added to the microspore embryo medium (osmotic potential = 25.5 bars). Time course experiments, to study the induction of napin and cruciferin gene expression demonstrated that the ABA effect occurred much more rapidly than the high osmoticum effect, although after 48 hours, the levels of napin or cruciferin mRNA detected were similar in both treatments. This difference in the rates of induction is consistent with the idea that the osmotic effect may be mediated by ABA which is synthesized in response to the reduced water potential. Measurements of ABA (by gas chromatography-mass spectrometry using ({sup 2}H{sub 6})ABA as an internal standard) present in microspore embryos during sorbitol treatment and in embryos treated with 10 micromolar ABA were performed to investigate this possibility. Within 2 hours of culture on high osmoticum the level of ABA increased substantially and significantly above control and reached a maximum concentration within 24 hours. This elevated concentration was maintained for 48 hours after culturing and represents a sixfold increase over control embryos.

  6. Influence of Nitrogen Source, Thiamine, and Light on Biosynthesis of Abscisic Acid by Cercospora rosicola Passerini

    PubMed Central

    Norman, Shirley M.; Maier, Vincent P.; Echols, Linda C.

    1981-01-01

    Abscisic acid production by Cercospora rosicola Passerini in liquid shake culture was measured with different amino acids in combination and singly as nitrogen sources and with different amounts of thiamine in the media. Production of abscisic acid was highest with aspartic acid-glutamic acid and aspartic acid-glutamic acid-serine mixtures as nitrogen sources. Single amino acids that supported the highest production of abscisic acid were asparagine and monosodium glutamate. Thiamine was important for abscisic acid production. Leucine inhibited abscisic acid production. C. rosicola produced abscisic acid in the dark, but production more than doubled in the presence of light. PMID:16345761

  7. Abscisic Acid Transport in Human Erythrocytes*

    PubMed Central

    Vigliarolo, Tiziana; Guida, Lucrezia; Millo, Enrico; Fresia, Chiara; Turco, Emilia; De Flora, Antonio; Zocchi, Elena

    2015-01-01

    Abscisic acid (ABA) is a plant hormone involved in the response to environmental stress. Recently, ABA has been shown to be present and active also in mammals, where it stimulates the functional activity of innate immune cells, of mesenchymal and hemopoietic stem cells, and insulin-releasing pancreatic β-cells. LANCL2, the ABA receptor in mammalian cells, is a peripheral membrane protein that localizes at the intracellular side of the plasma membrane. Here we investigated the mechanism enabling ABA transport across the plasmamembrane of human red blood cells (RBC). Both influx and efflux of [3H]ABA occur across intact RBC, as detected by radiometric and chromatographic methods. ABA binds specifically to Band 3 (the RBC anion transporter), as determined by labeling of RBC membranes with biotinylated ABA. Proteoliposomes reconstituted with human purified Band 3 transport [3H]ABA and [35S]sulfate, and ABA transport is sensitive to the specific Band 3 inhibitor 4,4′-diisothiocyanostilbene-2,2′-disulfonic acid. Once inside RBC, ABA stimulates ATP release through the LANCL2-mediated activation of adenylate cyclase. As ATP released from RBC is known to exert a vasodilator response, these results suggest a role for plasma ABA in the regulation of vascular tone. PMID:25847240

  8. Response of Cultured Maize Cells to (+)-Abscisic Acid, (-)-Abscisic Acid, and Their Metabolites.

    PubMed Central

    Balsevich, J. J.; Cutler, A. J.; Lamb, N.; Friesen, L. J.; Kurz, E. U.; Perras, M. R.; Abrams, S. R.

    1994-01-01

    The metabolism and effects of (+)-S- and (-)-R-abscisic acid (ABA) and some metabolites were studied in maize (Zea mays L. cv Black Mexican Sweet) suspension-cultured cells. Time-course studies of metabolite formation were performed in both cells and medium via analytical high-performance liquid chromatography. Metabolites were isolated and identified using physical and chemical methods. At 10 [mu]M concentration and 28[deg] C, (+)-ABA was metabolized within 24 h, yielding natural (-)-phaseic acid [(-)-PA] as the major product. The unnatural enantiomer (-)-ABA was less than 50% metabolized within 24 h and gave primarily (-)-7[prime]-hydroxyABA [(-)-7[prime]-HOABA], together with (+)-PA and ABA glucose ester. The distribution of metabolites in cells and medium was different, reflecting different sites of metabolism and membrane permeabilities of conjugated and nonconjugated metabolites. The results imply that (+)-ABA was oxidized to (-)-PA inside the cell, whereas (-)-ABA was converted to (-)-7[prime]-HOABA at the cell surface. Growth of maize cells was inhibited by both (+)- and (-)-ABA, with only weak contributions from their metabolites. The concentration of (+)-ABA that caused a 50% inhibition of growth of maize cells was approximately 1 [mu]M, whereas that for its metabolite (-)-PA was approximately 50 [mu]M. (-)-ABA was less active than (+)-ABA, with 50% growth inhibition observed at about 10 [mu]M. (-)-7[prime]-HOABA was only weakly active, with 50% inhibition caused by approximately 500 [mu]M. Time-course studies of medium pH indicated that (+)-ABA caused a transient pH increase (+0.3 units) at 6 h after addition that was not observed in controls or in samples treated with (-)-PA. The effect of (-)-ABA on medium Ph was marginal. No racemization at C-1[prime] of (+)-ABA, (-)-ABA, or metabolites was observed during the studies. PMID:12232311

  9. GENETIC ANALYSIS OF ABSCISIC ACID BIOSYNTHESIS

    SciTech Connect

    MCCARTY D R

    2012-01-10

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

  10. Abscisic acid signaling through cyclic ADP-ribose in plants

    SciTech Connect

    Wu, Yan; Kuzma, J.; Marechal, E.

    1997-12-19

    Abscisic acid (ABA) is the primary hormone that mediates plant responses to stresses such as cold, drought, and salinity. Single-cell microinjection experiments in tomato were used to identify possible intermediates involved in ABA signal transduction. Cyclic ADP-ribose (cADPR) was identified as a signaling molecule in the ABA response and was shown to exert its effects by way of calcium. Bioassay experiments showed that the amounts of cADPR in Arabidopsis thaliana plants increased in response to ABA treatment and before ABA-induced gene expression.

  11. Incorporation of oxygen into abscisic acid and phaseic acid for molecular oxygen

    SciTech Connect

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

    1984-05-01

    Abscisic acid accumulates in detached, wilted leaves of Xanthium strumariu. When these leaves are subsequently rehydrated, phaseic acid, a catabolite of abscisic acid, accumulates. Analysis by gas chromatography-mass spectrometry of phaseic acid isolated from stressed and subsequently rehydrated leaves placed in an atmosphere containing 20% /sup 18/O/sub 2/ and 80% N/sub 2/ indicates that one atom of /sup 18/O is incorporated in the 6'-hydroxymethyl group of phaseic acid. This suggests that the enzyme that converts abscisic acid to phaseic acid is an oxygenase. Analysis by gas chromatography-mass spectrometry of abscisic acid isolated from stressed leaves kept in an atmosphere containing /sup 18/O/sub 2/ indicates that one atom of /sup 18/O is presented in the carboxyl group of abscisic acid. Thus, when abscisic acid accumulates in water-streesed leaves, only one of the four oxygens present in the abscisic acid molecule is derived from molecular oxygen. This suggest that either (a) the oxygen present in the 1'-, 4'-, and one of the two oxygens at the 1-position of abscisic acid arise from water, or (b) there exists a stored precursor with oxygen atoms already present in the 1'- and 4'-positions of abscisic acid which is converted to abscisic acid under conditions of water stress. 17 references, 2 figures, 1 tables.

  12. Action of Natural Abscisic Acid Precursors and Catabolites on Abscisic Acid Receptor Complexes1[W

    PubMed Central

    Kepka, Michal; Benson, Chantel L.; Gonugunta, Vijay K.; Nelson, Ken M.; Christmann, Alexander; Grill, Erwin; Abrams, Suzanne R.

    2011-01-01

    The phytohormone abscisic acid (ABA) regulates stress responses and controls numerous aspects of plant growth and development. Biosynthetic precursors and catabolites of ABA have been shown to trigger ABA responses in physiological assays, but it is not clear whether these are intrinsically active or whether they are converted into ABA in planta. In this study, we analyzed the effect of ABA precursors, conjugates, and catabolites on hormone signaling in Arabidopsis (Arabidopsis thaliana). The compounds were also tested in vitro for their ability to regulate the phosphatase moiety of ABA receptor complexes consisting of the protein phosphatase 2C ABI2 and the coreceptors RCAR1/PYL9, RCAR3/PYL8, and RCAR11/PYR1. Using mutants defective in ABA biosynthesis, we show that the physiological activity associated with ABA precursors derives predominantly from their bioconversion to ABA. The ABA glucose ester conjugate, which is the most widespread storage form of ABA, showed weak ABA-like activity in germination assays and in triggering ABA signaling in protoplasts. The ABA conjugate and precursors showed negligible activity as a regulatory ligand of the ABI2/RCAR receptor complexes. The majority of ABA catabolites were inactive in our assays. To analyze the chemically unstable 8′- and 9′-hydroxylated ABA catabolites, we used stable tetralone derivatives of these compounds, which did trigger selective ABA responses. ABA synthetic analogs exhibited differential activity as regulatory ligands of different ABA receptor complexes in vitro. The data show that ABA precursors, catabolites, and conjugates have limited intrinsic bioactivity and that both natural and synthetic ABA-related compounds can be used to probe the structural requirements of ABA ligand-receptor interactions. PMID:21976481

  13. Arabidopsis Glutamate Receptor Homolog3.5 Modulates Cytosolic Ca2+ Level to Counteract Effect of Abscisic Acid in Seed Germination1[OPEN

    PubMed Central

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

    2015-01-01

    Seed germination is a critical step in a plant’s life cycle that allows successful propagation and is therefore strictly controlled by endogenous and environmental signals. However, the molecular mechanisms underlying germination control remain elusive. Here, we report that the Arabidopsis (Arabidopsis thaliana) glutamate receptor homolog3.5 (AtGLR3.5) is predominantly expressed in germinating seeds and increases cytosolic Ca2+ concentration that counteracts the effect of abscisic acid (ABA) to promote germination. Repression of AtGLR3.5 impairs cytosolic Ca2+ concentration elevation, significantly delays germination, and enhances ABA sensitivity in seeds, whereas overexpression of AtGLR3.5 results in earlier germination and reduced seed sensitivity to ABA. Furthermore, we show that Ca2+ suppresses the expression of ABSCISIC ACID INSENSITIVE4 (ABI4), a key transcription factor involved in ABA response in seeds, and that ABI4 plays a fundamental role in modulation of Ca2+-dependent germination. Taken together, our results provide molecular genetic evidence that AtGLR3.5-mediated Ca2+ influx stimulates seed germination by antagonizing the inhibitory effects of ABA through suppression of ABI4. These findings establish, to our knowledge, a new and pivotal role of the plant glutamate receptor homolog and Ca2+ signaling in germination control and uncover the orchestrated modulation of the AtGLR3.5-mediated Ca2+ signal and ABA signaling via ABI4 to fine-tune the crucial developmental process, germination, in Arabidopsis. PMID:25681329

  14. Label-free quantitative proteomic analysis of abscisic acid effect in early-stage soybean under flooding.

    PubMed

    Komatsu, Setsuko; Han, Chao; Nanjo, Yohei; Altaf-Un-Nahar, Most; Wang, Kun; He, Dongli; Yang, Pingfang

    2013-11-01

    Flooding is a serious problem for soybean cultivation because it markedly reduces growth. To investigate the role of phytohormones in soybean under flooding stress, gel-free proteomic technique was used. When 2-day-old soybeans were flooded, the content of abscisic acid (ABA) did not decrease in the root, though its content decreased in untreated plant. When ABA was added during flooding treatment, survival ratio was improved compared with that of soybeans flooded without ABA. When 2-day-old soybeans were flooded with ABA, the abundance of proteins related to cell organization, vesicle transport and glycolysis decreased compared with those in root of soybeans flooded without ABA. Furthermore, the nuclear proteins were analyzed to identify the transcriptional regulation. The abundance of 34 nuclear proteins such as histone deacetylase and U2 small nuclear ribonucleoprotein increased by ABA supplementation under flooding; however, 35 nuclear proteins such as importin alpha, chromatin remodeling factor, zinc finger protein, transducin, and cell division 5 protein decreased. Of them, the mRNA expression levels of cell division cycle 5 protein, C2H2 zinc finger protein SERRATE, CCCH type zinc finger family protein, and transducin were significantly down-regulated under the ABA treatment. These results suggest that ABA might be involved in the enhancement of flooding tolerance of soybean through the control of energy conservation via glycolytic system and the regulation on zinc finger proteins, cell division cycle 5 protein and transducin. PMID:23808807

  15. Effects of soil freezing and drought stress on abscisic acid content of sugar maple sap and leaves.

    PubMed

    Bertrand, A; Robitaille, G; Nadeau, P; Boutin, R

    1994-04-01

    In 1991 and 1992, mature maple trees (Acer saccharum Marsh.) were freeze-stressed or drought-stressed by preventing precipitation (snow or rain) from reaching the forest floor under selected trees. Lack of snow cover caused a decrease in soil temperature to well below 0 degrees C from December to April and a lowering of the soil water content to 10%. The abscisic acid (ABA) concentration in the spring sap of deep-soil frost-stressed trees was significantly higher than in control or drought-stressed trees. The increase in ABA concentration in the xylem sap in the spring of 1991 and 1992 preceded symptoms of canopy decline and a decrease in leaf area that were observed during the summers of 1991 and 1992. These results suggest a role for ABA in root-to-shoot communication in response to environmental stress. The largest differences in ABA concentration induced by the treatments was found in sap collected at the end of sap flow. The increase in ABA concentration in spring sap at the end of the sap flow could be used as an early indicator of stress suffered by trees during the winter. Not only did the increase in ABA concentration occur before any visible symptoms of tree decline appeared, but the trees that showed the most evident decline had the highest ABA concentrations in the spring sap. Leaf ABA concentration was not a good indicator of induced stress. PMID:14967696

  16. Rapid Phosphoproteomic Effects of Abscisic Acid (ABA) on Wild-Type and ABA Receptor-Deficient A. thaliana Mutants*

    PubMed Central

    Minkoff, Benjamin B.; Stecker, Kelly E.; Sussman, Michael R.

    2015-01-01

    Abscisic acid (ABA)1 is a plant hormone that controls many aspects of plant growth, including seed germination, stomatal aperture size, and cellular drought response. ABA interacts with a unique family of 14 receptor proteins. This interaction leads to the activation of a family of protein kinases, SnRK2s, which in turn phosphorylate substrates involved in many cellular processes. The family of receptors appears functionally redundant. To observe a measurable phenotype, four of the fourteen receptors have to be mutated to create a multilocus loss-of-function quadruple receptor (QR) mutant, which is much less sensitive to ABA than wild-type (WT) plants. Given these phenotypes, we asked whether or not a difference in ABA response between the WT and QR backgrounds would manifest on a phosphorylation level as well. We tested WT and QR mutant ABA response using isotope-assisted quantitative phosphoproteomics to determine what ABA-induced phosphorylation changes occur in WT plants within 5 min of ABA treatment and how that phosphorylation pattern is altered in the QR mutant. We found multiple ABA-induced phosphorylation changes that occur within 5 min of treatment, including three SnRK2 autophosphorylation events and phosphorylation on SnRK2 substrates. The majority of robust ABA-dependent phosphorylation changes observed were partially diminished in the QR mutant, whereas many smaller ABA-dependent phosphorylation changes observed in the WT were not responsive to ABA in the mutant. A single phosphorylation event was increased in response to ABA treatment in both the WT and QR mutant. A portion of the discovery data was validated using selected reaction monitoring-based targeted measurements on a triple quadrupole mass spectrometer. These data suggest that different subsets of phosphorylation events depend upon different subsets of the ABA receptor family to occur. Altogether, these data expand our understanding of the model by which the family of ABA receptors directs

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  18. Abscisic acid represses the transcription of chloroplast genes*

    PubMed Central

    Yamburenko, Maria V.; Zubo, Yan O.; Börner, Thomas

    2013-01-01

    Numerous studies have shown effects of abscisic acid (ABA) on nuclear genes encoding chloroplast-localized proteins. ABA effects on the transcription of chloroplast genes, however, have not been investigated yet thoroughly. This work, therefore, studied the effects of ABA (75 μM) on transcription and steady-state levels of transcripts in chloroplasts of basal and apical segments of primary leaves of barley (Hordeum vulgare L.). Basal segments consist of young cells with developing chloroplasts, while apical segments contain the oldest cells with mature chloroplasts. Exogenous ABA reduced the chlorophyll content and caused changes of the endogenous concentrations not only of ABA but also of cytokinins to different extents in the basal and apical segments. It repressed transcription by the chloroplast phage-type and bacteria-type RNA polymerases and lowered transcript levels of most investigated chloroplast genes drastically. ABA did not repress the transcription of psbD and a few other genes and even increased psbD mRNA levels under certain conditions. The ABA effects on chloroplast transcription were more pronounced in basal vs. apical leaf segments and enhanced by light. Simultaneous application of cytokinin (22 μM 6-benzyladenine) minimized the ABA effects on chloroplast gene expression. These data demonstrate that ABA affects the expression of chloroplast genes differentially and points to a role of ABA in the regulation and coordination of the activities of nuclear and chloroplast genes coding for proteins with functions in photosynthesis. PMID:24078671

  19. Export of Abscisic Acid, 1-Aminocyclopropane-1-Carboxylic Acid, Phosphate, and Nitrate from Roots to Shoots of Flooded Tomato Plants (Accounting for Effects of Xylem Sap Flow Rate on Concentration and Delivery).

    PubMed Central

    Else, M. A.; Hall, K. C.; Arnold, G. M.; Davies, W. J.; Jackson, M. B.

    1995-01-01

    We determined whether root stress alters the output of physiologically active messages passing from roots to shoots in the transpiration stream. Concentrations were not good measures of output. This was because changes in volume flow of xylem sap caused either by sampling procedures or by effects of root stress on rates of whole-plant transpiration modified concentrations simply by dilution. Thus, delivery rate (concentration x sap flow rate) was preferred to concentration as a measure of solute output from roots. To demonstrate these points, 1-aminocyclopropane-1-carboxylic acid (ACC), abscisic acid, phosphate, nitrate, and pH were measured in xylem sap of flooded and well-drained tomato (Lycopersicon esculentum Mill., cv Ailsa Craig) plants expressed at various rates from pressurized detopped roots. Concentrations decreased as sap flow rates were increased. However, dilution of solutes was often less than proportional to flow, especially in flooded plants. Thus, sap flowing through detopped roots at whole-plant transpiration rates was used to estimate solute delivery rates in intact plants. On this basis, delivery of ACC from roots to shoots was 3.1-fold greater in plants flooded for 24 h than in well-drained plants, and delivery of phosphate was 2.3-fold greater. Delivery rates of abscisic acid and nitrate in flooded plants were only 11 and 7%, respectively, of those in well-drained plants. PMID:12228364

  20. Abscisic acid and pyrabactin improve vitamin C contents in raspberries.

    PubMed

    Miret, Javier A; Munné-Bosch, Sergi

    2016-07-15

    Abscisic acid (ABA) is a plant growth regulator with roles in senescence, fruit ripening and environmental stress responses. ABA and pyrabactin (a non-photosensitive ABA agonist) effects on red raspberry (Rubus idaeus L.) fruit development (including ripening) were studied, with a focus on vitamin and antioxidant composition. Application of ABA and/or pyrabactin just after fruit set did not affect the temporal pattern of fruit development and ripening; neither provitamin A (carotenoids) nor vitamin E contents were modified. In contrast, ABA and pyrabactin altered the vitamin C redox state at early stages of fruit development and more than doubled vitamin C contents at the end of fruit ripening. These were partially explained by changes in ascorbate oxidation and recycling. Therefore, ABA and pyrabactin applications may be used to increase vitamin C content of ripe fruits, increasing fruit quality and value. However, treatments containing pyrabactin-combined with ABA or alone-diminished protein content, thus partially limiting its potential applicability. PMID:26948608

  1. Abscisic acid perception and signaling: structural mechanisms and applications

    PubMed Central

    Ng, Ley Moy; Melcher, Karsten; Teh, Bin Tean; Xu, H Eric

    2014-01-01

    Adverse environmental conditions are a threat to agricultural yield and therefore exert a global effect on livelihood, health and the economy. Abscisic acid (ABA) is a vital plant hormone that regulates abiotic stress tolerance, thereby allowing plants to cope with environmental stresses. Previously, attempts to develop a complete understanding of the mechanisms underlying ABA signaling have been hindered by difficulties in the identification of bona fide ABA receptors. The discovery of the PYR/PYL/RCAR family of ABA receptors therefore represented a major milestone in the effort to overcome these roadblocks; since then, many structural and functional studies have provided detailed insights into processes ranging from ABA perception to the activation of ABA-responsive gene transcription. This understanding of the mechanisms of ABA perception and signaling has served as the basis for recent, preliminary developments in the genetic engineering of stress-resistant crops as well as in the design of new synthetic ABA agonists, which hold great promise for the agricultural enhancement of stress tolerance. PMID:24786231

  2. Abscisic acid perception and signaling transduction in strawberry

    PubMed Central

    Li, Chunli; Jia, Haifeng; Chai, Yemao; Shen, Yuanyue

    2011-01-01

    On basis of fruit differential respiration and ethylene effects, climacteric and non-climacteric fruits have been classically defined. Over the past decades, the molecular mechanisms of climacteric fruit ripening were abundantly described and found to focus on ethylene perception and signaling transduction. In contrast, until our most recent breakthroughs, much progress has been made toward understanding the signaling perception and transduction mechanisms for abscisic acid (ABA) in strawberry, a model for non-climacteric fruit ripening. Our reports not only have provided several lines of strong evidences for ABA-regulated ripening of strawberry fruit, but also have demonstrated that homology proteins of Arabidopsis ABA receptors, including PYR/PYL/RCAR and ABAR/CHLH, act as positive regulators of ripening in response to ABA. These receptors also trigger a set of ABA downstream signaling components, and determine significant changes in the expression levels of both sugar and pigment metabolism-related genes that are closely associated with ripening. Soluble sugars, especially sucrose, may act as a signal molecular to trigger ABA accumulation through an enzymatic action of 9-cis-epoxycarotenoid dioxygenase 1 (FaNCED1). This mini-review offers an overview of these processes and also outlines the possible, molecular mechanisms for ABA in the regulation of strawberry fruit ripening through the ABA receptors. PMID:22095148

  3. Abscisic Acid and Abiotic Stress Tolerance in Crop Plants

    PubMed Central

    Sah, Saroj K.; Reddy, Kambham R.; Li, Jiaxu

    2016-01-01

    Abiotic stress is a primary threat to fulfill the demand of agricultural production to feed the world in coming decades. Plants reduce growth and development process during stress conditions, which ultimately affect the yield. In stress conditions, plants develop various stress mechanism to face the magnitude of stress challenges, although that is not enough to protect them. Therefore, many strategies have been used to produce abiotic stress tolerance crop plants, among them, abscisic acid (ABA) phytohormone engineering could be one of the methods of choice. ABA is an isoprenoid phytohormone, which regulates various physiological processes ranging from stomatal opening to protein storage and provides adaptation to many stresses like drought, salt, and cold stresses. ABA is also called an important messenger that acts as the signaling mediator for regulating the adaptive response of plants to different environmental stress conditions. In this review, we will discuss the role of ABA in response to abiotic stress at the molecular level and ABA signaling. The review also deals with the effect of ABA in respect to gene expression. PMID:27200044

  4. Mechanisms of abscisic acid-mediated control of stomatal aperture.

    PubMed

    Munemasa, Shintaro; Hauser, Felix; Park, Jiyoung; Waadt, Rainer; Brandt, Benjamin; Schroeder, Julian I

    2015-12-01

    Drought stress triggers an increase in the level of the plant hormone abscisic acid (ABA), which initiates a signaling cascade to close stomata and reduce water loss. Recent studies have revealed that guard cells control cytosolic ABA concentration through the concerted actions of biosynthesis, catabolism as well as transport across membranes. Substantial progress has been made at understanding the molecular mechanisms of how the ABA signaling core module controls the activity of anion channels and thereby stomatal aperture. In this review, we focus on our current mechanistic understanding of ABA signaling in guard cells including the role of the second messenger Ca(2+) as well as crosstalk with biotic stress responses. PMID:26599955

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

    PubMed

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

    2016-06-01

    In the past, a conventional wisdom has been that abscisic acid (ABA) is a xylem-transported hormone that is synthesized in the roots, while acting in the shoot to close stomata in response to a decrease in plant water status. Now, however, evidence from two studies, which we have conducted independently, challenges this root-sourced ABA paradigm. We show that foliage-derived ABA has a major influence over root development and that leaves are the predominant location for ABA biosynthesis during drought stress. PMID:27031537

  6. Drought, Abscisic Acid and Transpiration Rate Effects on the Regulation of PIP Aquaporin Gene Expression and Abundance in Phaseolus vulgaris Plants

    PubMed Central

    AROCA, RICARDO; FERRANTE, ANTONIO; VERNIERI, PAOLO; CHRISPEELS, MAARTEN J.

    2006-01-01

    • Background and Aims Drought causes a decline of root hydraulic conductance, which aside from embolisms, is governed ultimately by aquaporins. Multiple factors probably regulate aquaporin expression, abundance and activity in leaf and root tissues during drought; among these are the leaf transpiration rate, leaf water status, abscisic acid (ABA) and soil water content. Here a study is made of how these factors could influence the response of aquaporin to drought. • Methods Three plasma membrane intrinsic proteins (PIPs) or aquaporins were cloned from Phaseolus vulgaris plants and their expression was analysed after 4 d of water deprivation and also 1 d after re-watering. The effects of ABA and of methotrexate (MTX), an inhibitor of stomatal opening, on gene expression and protein abundance were also analysed. Protein abundance was examined using antibodies against PIP1 and PIP2 aquaporins. At the same time, root hydraulic conductance (L), transpiration rate, leaf water status and ABA tissue concentration were measured. • Key Results None of the treatments (drought, ABA or MTX) changed the leaf water status or tissue ABA concentration. The three treatments caused a decline in the transpiration rate and raised PVPIP2;1 gene expression and PIP1 protein abundance in the leaves. In the roots, only the drought treatment raised the expression of the three PIP genes examined, while at the same time diminishing PIP2 protein abundance and L. On the other hand, ABA raised both root PIP1 protein abundance and L. • Conclusions The rise of PvPIP2;1 gene expression and PIP1 protein abundance in the leaves of P. vulgaris plants subjected to drought was correlated with a decline in the transpiration rate. At the same time, the increase in the expression of the three PIP genes examined caused by drought and the decline of PIP2 protein abundance in the root tissues were not correlated with any of the parameters measured. PMID:17028296

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

    SciTech Connect

    Bruzzone, Santina; Battaglia, Florinda; Mannino, Elena; Parodi, Alessia; Fruscione, Floriana; Basile, Giovanna; Salis, Annalisa; Sturla, Laura; Negrini, Simone; Kalli, Francesca; Stringara, Silvia; Filaci, Gilberto; and others

    2012-05-25

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

  8. Abscisic Acid Uridine Diphosphate Glucosyltransferases Play a Crucial Role in Abscisic Acid Homeostasis in Arabidopsis1[C][W

    PubMed Central

    Dong, Ting; Xu, Zheng-Yi; Park, Youngmin; Kim, Dae Heon; Lee, Yongjik; Hwang, Inhwan

    2014-01-01

    The phytohormone abscisic acid (ABA) is crucial for plant growth and adaptive responses to various stress conditions. Plants continuously adjust the ABA level to meet physiological needs, but how ABA homeostasis occurs is not fully understood. This study provides evidence that UGT71B6, an ABA uridine diphosphate glucosyltransferase (UGT), and its two closely related homologs, UGT71B7 and UGT71B8, play crucial roles in ABA homeostasis and in adaptation to dehydration, osmotic stress, and high-salinity stresses in Arabidopsis (Arabidopsis thaliana). UGT RNA interference plants that had low levels of these three UGT transcripts displayed hypersensitivity to exogenous ABA and high-salt conditions during germination and exhibited a defect in plant growth. However, the ectopic expression of UGT71B6 in the atbg1 (for β-glucosidase) mutant background aggravated the ABA-deficient phenotype of atbg1 mutant plants. In addition, modulation of the expression of the three UGTs affects the expression of CYP707A1 to CYP707A4, which encode ABA 8′-hydroxylases; four CYP707As were expressed at higher levels in the UGT RNA interference plants but at lower levels in the UGT71B6:GFP-overexpressing plants. Based on these data, this study proposes that UGT71B6 and its two homologs play a critical role in ABA homeostasis by converting active ABA to an inactive form (abscisic acid-glucose ester) depending on intrinsic cellular and environmental conditions in plants. PMID:24676855

  9. Synthesis and biological activity of tetralone abscisic acid analogues.

    PubMed

    Nyangulu, James M; Nelson, Ken M; Rose, Patricia A; Gai, Yuanzhu; Loewen, Mary; Lougheed, Brenda; Quail, J Wilson; Cutler, Adrian J; Abrams, Suzanne R

    2006-04-01

    Bicyclic analogues of the plant hormone abscisic acid (ABA) were designed to incorporate the structural elements and functional groups of the parent molecule that are required for biological activity. The resulting tetralone analogues were predicted to have enhanced biological activity in plants, in part because oxidized products would not cyclize to forms corresponding to the inactive catabolite phaseic acid. The tetralone analogues were synthesized in seven steps from 1-tetralone and a range of analogues were accessible through a second route starting with 2-methyl-1-naphthol. Tetralone ABA 8 was found to have greater activity than ABA in two bioassays. The absolute configuration of (+)-8 was established by X-ray crystallography of a RAMP hydrazone derivative. The hydroxymethyl compounds 10 and 11, analogues for studying the roles of 8- and 9-hydroxy ABA 3 and 6, were also synthesized and found to be active. PMID:16557330

  10. Morphogenetic role of kinetin and abscisic acid in the moss Physcomitrium.

    PubMed

    Menon, M K; Lal, M

    1974-12-01

    In the presence of kinetin, a supposedly gametophytic bud inducing substance, the secondary protonema of the moss Physcomitrium pyriforme Brid., as well as producing leafy gametophytes, continued to exhibit its normal tendency of forming sporophytic buds (i.e. buds with apical cells having two cutting faces). Also remarkable was that callus derived from the secondary protonema, when cultured in a kinetin supplemented liquid medium, formed exclusively apogamous sporophytic buds with a virtual exclusion of gametophytes. In the presence of abscisic acid, the elongation of protonemal cells as well as their differentiation was markedly suppressed. This effect was manifest even when abscisic acid was used in conjunction with kinetin. It is suggested that rather than having a morphoregulatory role, kinetin may be responsible merely for enhancing cell proliferation. The determination of an apical cell with two cutting faces (sporophytic) or one with three cutting faces (gametophytic) is under the control of other factors both external, (e.g. sucrose) and internal. It is proposed that abscisic acid can suppress the usual differentiational capacity of the moss tissue, even in a favourable environment. PMID:24458926

  11. Tomato ABSCISIC ACID STRESS RIPENING (ASR) Gene Family Revisited

    PubMed Central

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

    2014-01-01

    Tomato ABSCISIC ACID RIPENING 1 (ASR1) was the first cloned plant ASR gene. ASR orthologs were then cloned from a large number of monocot, dicot and gymnosperm plants, where they are mostly involved in response to abiotic (drought and salinity) stress and fruit ripening. The tomato genome encodes five ASR genes: ASR1, 2, 3 and 5 encode low-molecular-weight proteins (ca. 110 amino acid residues each), whereas ASR4 encodes a 297-residue polypeptide. Information on the expression of the tomato ASR gene family is scarce. We used quantitative RT-PCR to assay the expression of this gene family in plant development and in response to salt and osmotic stresses. ASR1 and ASR4 were the main expressed genes in all tested organs and conditions, whereas ASR2 and ASR3/5 expression was two to three orders of magnitude lower (with the exception of cotyledons). ASR1 is expressed in all plant tissues tested whereas ASR4 expression is limited to photosynthetic organs and stamens. Essentially, ASR1 accounted for most of ASR gene expression in roots, stems and fruits at all developmental stages, whereas ASR4 was the major gene expressed in cotyledons and young and fully developed leaves. Both ASR1 and ASR4 were expressed in flower organs, with ASR1 expression dominating in stamens and pistils, ASR4 in sepals and petals. Steady-state levels of ASR1 and ASR4 were upregulated in plant vegetative organs following exposure to salt stress, osmotic stress or the plant abiotic stress hormone abscisic acid (ABA). Tomato plants overexpressing ASR1 displayed enhanced survival rates under conditions of water stress, whereas ASR1-antisense plants displayed marginal hypersensitivity to water withholding. PMID:25310287

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

    PubMed

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

    2014-01-01

    Tomato ABSCISIC ACID RIPENING 1 (ASR1) was the first cloned plant ASR gene. ASR orthologs were then cloned from a large number of monocot, dicot and gymnosperm plants, where they are mostly involved in response to abiotic (drought and salinity) stress and fruit ripening. The tomato genome encodes five ASR genes: ASR1, 2, 3 and 5 encode low-molecular-weight proteins (ca. 110 amino acid residues each), whereas ASR4 encodes a 297-residue polypeptide. Information on the expression of the tomato ASR gene family is scarce. We used quantitative RT-PCR to assay the expression of this gene family in plant development and in response to salt and osmotic stresses. ASR1 and ASR4 were the main expressed genes in all tested organs and conditions, whereas ASR2 and ASR3/5 expression was two to three orders of magnitude lower (with the exception of cotyledons). ASR1 is expressed in all plant tissues tested whereas ASR4 expression is limited to photosynthetic organs and stamens. Essentially, ASR1 accounted for most of ASR gene expression in roots, stems and fruits at all developmental stages, whereas ASR4 was the major gene expressed in cotyledons and young and fully developed leaves. Both ASR1 and ASR4 were expressed in flower organs, with ASR1 expression dominating in stamens and pistils, ASR4 in sepals and petals. Steady-state levels of ASR1 and ASR4 were upregulated in plant vegetative organs following exposure to salt stress, osmotic stress or the plant abiotic stress hormone abscisic acid (ABA). Tomato plants overexpressing ASR1 displayed enhanced survival rates under conditions of water stress, whereas ASR1-antisense plants displayed marginal hypersensitivity to water withholding. PMID:25310287

  13. Abscisic acid biosynthesis in isolated embryos of Zea mays L

    SciTech Connect

    Gage, D.A.; Fong, F.; Zeevaart, J.A.D. Texas A M Univ., College Station )

    1989-04-01

    Previous labeling experiments with {sup 18}O{sub 2} have supported the hypothesis that stress-induced abscisic acid (ABA) is synthesized through an indirect pathway involving an oxygenated carotenoid (xanthophyll) as a precursor. To investigate ABA formation under nonstress conditions, an {sup 18}O{sub 2} labeling experiment was conducted with isolated embryos from in vitro grown maize (Zea mays L.) kernels. Of the ABA produced during the incubation in {sup 18}O{sub 2}, three-fourths contained a single {sup 18}O atom located in the carboxyl group. Approximately one-fourth of the ABA synthesized during the experiment contained two {sup 18}O atoms. These results suggest that ABA synthesized in maize embryos under nonstress conditions also proceeds via the indirect pathway, requiring a xanthophyll precursor. It was also found that the newly synthesized ABA was preferentially released into the surrounding medium.

  14. Farnesylation mediates brassinosteroid biosynthesis to regulate abscisic acid responses.

    PubMed

    Northey, Julian G B; Liang, Siyu; Jamshed, Muhammad; Deb, Srijani; Foo, Eloise; Reid, James B; McCourt, Peter; Samuel, Marcus A

    2016-01-01

    Protein farnesylation is a post-translational modification involving the addition of a 15-carbon farnesyl isoprenoid to the carboxy terminus of select proteins(1-3). Although the roles of this lipid modification are clear in both fungal and animal signalling, many of the mechanistic functions of farnesylation in plant signalling are still unknown. Here, we show that CYP85A2, the cytochrome P450 enzyme that performs the last step in brassinosteroid biosynthesis (conversion of castasterone to brassinolide)(4), must be farnesylated to function in Arabidopsis. Loss of either CYP85A2 or CYP85A2 farnesylation results in reduced brassinolide accumulation and increased plant responsiveness to the hormone abscisic acid (ABA) and overall drought tolerance, explaining previous observations(5). This result not only directly links farnesylation to brassinosteroid biosynthesis but also suggests new strategies to maintain crop yield under challenging climatic conditions. PMID:27455172

  15. The role of brassinosteroids and abscisic acid in stomatal development.

    PubMed

    Serna, Laura

    2014-08-01

    Gas exchange with the atmosphere is regulated through the stomata. This process relies on both the degree and duration of stomatal opening, and the number and patterning of these structures in the plant surface. Recent work has revealed that brassinosteroids and abscisic acid (ABA), which control stomatal opening, also repress stomatal development in cotyledons and leaves of at least some plants. It is speculated that, in Arabidopsis, these phytohormones control the same steps of this developmental process, most probably, through the regulation of the same mitogen-activated protein (MAP) kinase module. The conservation, in seeds plants, of components downstream of this module with MAP kinase target domains, suggests that these proteins are also regulated by these cascades, which, in turn, may be regulated by brassinosteroids and/or ABA. PMID:25017164

  16. Abscisic acid transporters cooperate to control seed germination

    PubMed Central

    Kang, Joohyun; Yim, Sojeong; Choi, Hyunju; Kim, Areum; Lee, Keun Pyo; Lopez-Molina, Luis; Martinoia, Enrico; Lee, Youngsook

    2015-01-01

    Seed germination is a key developmental process that has to be tightly controlled to avoid germination under unfavourable conditions. Abscisic acid (ABA) is an essential repressor of seed germination. In Arabidopsis, it has been shown that the endosperm, a single cell layer surrounding the embryo, synthesizes and continuously releases ABA towards the embryo. The mechanism of ABA transport from the endosperm to the embryo was hitherto unknown. Here we show that four AtABCG transporters act in concert to deliver ABA from the endosperm to the embryo: AtABCG25 and AtABCG31 export ABA from the endosperm, whereas AtABCG30 and AtABCG40 import ABA into the embryo. Thus, this work establishes that radicle extension and subsequent embryonic growth are suppressed by the coordinated activity of multiple ABA transporters expressed in different tissues. PMID:26334616

  17. Arabidopsis YAK1 regulates abscisic acid response and drought resistance.

    PubMed

    Kim, Dongjin; Ntui, Valentine Otang; Xiong, Liming

    2016-07-01

    Abscisic acid (ABA) is an important phytohormone that controls several plant processes such as seed germination, seedling growth, and abiotic stress response. Here, we report that AtYak1 plays an important role in ABA signaling and postgermination growth in Arabidopsis. AtYak1 knockout mutant plants were hyposensitive to ABA inhibition of seed germination, cotyledon greening, seedling growth, and stomatal movement. atyak1-1 mutant plants display reduced drought stress resistance, as evidenced by water loss rate and survival rate. Molecular genetic analysis revealed that AtYak1 deficiency led to elevated expression of stomatal-related gene, MYB60, and down-regulation of several stress-responsive genes. Altogether, these results indicate that AtYak1 plays a role as a positive regulator in ABA-mediated drought response in Arabidopsis. PMID:27264339

  18. Long-term effects of abscisic acid (ABA) on the grape berry phenylpropanoid pathway: Gene expression and metabolite content.

    PubMed

    Villalobos-González, Luis; Peña-Neira, Alvaro; Ibáñez, Freddy; Pastenes, Claudio

    2016-08-01

    ABA has been proposed as the main signal triggering the onset of the ripening process in grapes, and modulating the secondary metabolism in grape berry skins. To determine the effect of ABA on secondary metabolism in berries, clusters of Carménère were sprayed with 0 μLL(-1) ABA; 50 μLL(-1) ABA and 100 μLL(-1) ABA during pre-véraison, and the gene expression of the transcription factors and enzymes of the phenylpropanoid pathway were assessed from véraison to 70 days after véraison (DAV). Additionally, flavonols, tannins and anthocyanins were assessed from véraison until harvest (110 DAV). ABA accelerated sugar and anthocyanin accumulation at véraison. The grape transcript abundance of VvDFR, VvANS, VvUFGT and VvMybA1, all peaking around véraison mimicked the concentration of ABA throughout the season. The highest anthocyanin concentration occurred 35 DAV for all treatments, but higher pigment concentrations were observed in ABA-treated berries at véraison and from 60 to 70 DAV to harvest. VvPAL was also increased by treatment at the higher concentration of ABA from véraison to 40 DAV. Regarding flavanol synthesis, VvLAR2 and VvMyb4A decreased from véraison until 40 DAV and then increased again until 70 DAV. Compared to the control, both ABA treatments resulted in a less-than-proportional reduction of the expression of both genes compared to the control and, after 40 DAV, in a more-than-proportional increase compared to the control, suggesting a long-term effect of the pre-véraison ABA spray on the berries. A concomitant increase in flavanols was observed in berries after 40 DAV, and this occurred at a higher extent in berries treated with the highest ABA concentration. PMID:27116369

  19. Effect of Inhibition of Abscisic Acid Accumulation on the Spatial Distribution of Elongation in the Primary Root and Mesocotyl of Maize at Low Water Potentials 1

    PubMed Central

    Saab, Imad N.; Sharp, Robert E.; Pritchard, Jeremy

    1992-01-01

    Previous work showed that accumulation of endogenous abscisic acid (ABA) acts both to maintain primary root growth and inhibit shoot growth in maize seedlings at low water potentials (ψw) (IN Saab, RE Sharp, J Pritchard, GS Voetberg [1990] Plant Physiol 93: 1329-1336). In this study, we have characterized the growth responses of the primary root and mesocotyl of maize (Zea mays L. cv FR27 × FRMo 17) to manipulation of ABA levels at low ψw with a high degree of spatial resolution to provide the basis for studies of the mechanism(s) of ABA action. In seedlings growing at low ψw and treated with fluridone to inhibit carotenoid (and ABA) biosynthesis, ABA levels were decreased in all locations of the root and mesocotyl growing zones compared with untreated seedlings growing at the same ψw. In the root, low ψw (−1.6 megapascals) caused a shortening of the growing zone, as reported previously. The fluridone treatment was associated with severe inhibition of root elongation rate, which resulted from further shortening of the growing zone. In the mesocotyl, low ψw (−0.3 megapascal) also resulted in a shortened growing zone. In contrast with the primary root, however, fluridone treatment prevented most of the inhibition of elongation and the shortening of the growing zone. Final cell length measurements indicated that the responses of both root and mesocotyl elongation to ABA manipulation at low ψw involve large effects on cell expansion. Measurements of the relative changes in root and shoot water contents and dry weights after transplanting to a ψw of −0.3 megapascal showed that the maintenance of shoot elongation in fluridone-treated seedlings was not attributable to increased water or seed-reserve availability resulting from inhibition of root growth. The results suggest a developmental gradient in tissue responsiveness to endogenous ABA in both the root and mesocotyl growing zones. In the root, the capacity for ABA to protect cell expansion at low

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

    PubMed Central

    SREEDHAR, LEKHA; WOLKERS, WILLEM F.; HOEKSTRA, FOLKERT A.; BEWLEY, J. DEREK

    2002-01-01

    Although somatic embryos of alfalfa (Medicago sativa L.) had acquired some tolerance to desiccation at the cotyledonary stage of development (22 d after plating), additional culturing in 20 μm abscisic acid (ABA) for 8 d induced greater desiccation tolerance, as determined by increased germination. Compared with fast drying, slow drying of the ABA‐treated embryos improved desiccation tolerance. However, slow drying of non‐ABA‐treated embryos led to the complete loss of germination capacity, while some fast‐dried embryos survived. An electron paramagnetic resonance spin probe technique and in vivo Fourier transform infrared microspectroscopy revealed that cellular membrane integrity and α‐helical protein secondary structure were maintained during drying in embryos cultured in media enriched with 20 μm ABA, but not in embryos cultured in the absence of ABA. Slow‐dried, non‐ABA‐treated embryos had low oligosaccharide to sucrose ratios, an increased proportion of β‐sheet protein secondary structures and broad membrane phase transitions extending over a temperature range of more than 60 °C, suggestive of irreversible phase separations. The spin probe study showed evidence of imbibitional damage, which could be alleviated by prehydration in humid air. These observations emphasize the importance of appropriate drying and prehydration protocols for the survival and storage of somatic embryos. It is suggested that ABA also plays a role in suppressing metabolism, thus increasing the level of desiccation tolerance; this is particularly evident under stressful conditions such as slow drying. PMID:12096799

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

    PubMed

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

    2002-04-01

    Although somatic embryos of alfalfa (Medicago sativa L.) had acquired some tolerance to desiccation at the cotyledonary stage of development (22 d after plating), additional culturing in 20 microm abscisic acid (ABA) for 8 d induced greater desiccation tolerance, as determined by increased germination. Compared with fast drying, slow drying of the ABA-treated embryos improved desiccation tolerance. However, slow drying of non-ABA-treated embryos led to the complete loss of germination capacity, while some fast-dried embryos survived. An electron paramagnetic resonance spin probe technique and in vivo Fourier transform infrared microspectroscopy revealed that cellular membrane integrity and a-helical protein secondary structure were maintained during drying in embryos cultured in media enriched with 20 microM ABA, but not in embryos cultured in the absence of ABA. Slow-dried, non-ABA-treated embryos had low oligosaccharide to sucrose ratios, an increased proportion of beta-sheet protein secondary structures and broad membrane phase transitions extending over a temperature range of more than 60 degrees C, suggestive of irreversible phase separations. The spin probe study showed evidence of imbibitional damage, which could be alleviated by prehydration in humid air. These observations emphasize the importance of appropriate drying and prehydration protocols for the survival and storage of somatic embryos. It is suggested that ABA also plays a role in suppressing metabolism, thus increasing the level of desiccation tolerance; this is particularly evident under stressful conditions such as slow drying. PMID:12096799

  2. Genetic control of abscisic acid biosynthesis in maize.

    PubMed

    Tan, B C; Schwartz, S H; Zeevaart, J A; McCarty, D R

    1997-10-28

    Abscisic acid (ABA), an apocarotenoid synthesized from cleavage of carotenoids, regulates seed maturation and stress responses in plants. The viviparous seed mutants of maize identify genes involved in synthesis and perception of ABA. Two alleles of a new mutant, viviparous14 (vp14), were identified by transposon mutagenesis. Mutant embryos had normal sensitivity to ABA, and detached leaves of mutant seedlings showed markedly higher rates of water loss than those of wild type. The ABA content of developing mutant embryos was 70% lower than that of wild type, indicating a defect in ABA biosynthesis. vp14 embryos were not deficient in epoxy-carotenoids, and extracts of vp14 embryos efficiently converted the carotenoid cleavage product, xanthoxin, to ABA, suggesting a lesion in the cleavage reaction. vp14 was cloned by transposon tagging. The VP14 protein sequence is similar to bacterial lignostilbene dioxygenases (LSD). LSD catalyzes a double-bond cleavage reaction that is closely analogous to the carotenoid cleavage reaction of ABA biosynthesis. Southern blots indicated a family of four to six related genes in maize. The Vp14 mRNA is expressed in embryos and roots and is strongly induced in leaves by water stress. A family of Vp14-related genes evidently controls the first committed step of ABA biosynthesis. These genes are likely to play a key role in the developmental and environmental control of ABA synthesis in plants. PMID:9342392

  3. Shoot-derived abscisic acid promotes root growth.

    PubMed

    McAdam, Scott A M; Brodribb, Timothy J; Ross, John J

    2016-03-01

    The phytohormone abscisic acid (ABA) plays a major role in regulating root growth. Most work to date has investigated the influence of root-sourced ABA on root growth during water stress. Here, we tested whether foliage-derived ABA could be transported to the roots, and whether this foliage-derived ABA had an influence on root growth under well-watered conditions. Using both application studies of deuterium-labelled ABA and reciprocal grafting between wild-type and ABA-biosynthetic mutant plants, we show that both ABA levels in the roots and root growth in representative angiosperms are controlled by ABA synthesized in the leaves rather than sourced from the roots. Foliage-derived ABA was found to promote root growth relative to shoot growth but to inhibit the development of lateral roots. Increased root auxin (IAA) levels in plants with ABA-deficient scions suggest that foliage-derived ABA inhibits root growth through the root growth-inhibitor IAA. These results highlight the physiological and morphological importance, beyond the control of stomata, of foliage-derived ABA. The use of foliar ABA as a signal for root growth has important implications for regulating root to shoot growth under normal conditions and suggests that leaf rather than root hydration is the main signal for regulating plant responses to moisture. PMID:26514625

  4. 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

  5. Abscisic Acid: Hidden Architect of Root System Structure

    PubMed Central

    Harris, Jeanne M.

    2015-01-01

    Plants modulate root growth in response to changes in the local environment, guided by intrinsic developmental genetic programs. The hormone Abscisic Acid (ABA) mediates responses to different environmental factors, such as the presence of nitrate in the soil, water stress and salt, shaping the structure of the root system by regulating the production of lateral roots as well as controlling root elongation by modulating cell division and elongation. Curiously, ABA controls different aspects of root architecture in different plant species, perhaps providing some insight into the great diversity of root architecture in different plants, both from different taxa and from different environments. ABA is an ancient signaling pathway, acquired well before the diversification of land plants. Nonetheless, how this ancient signaling module is implemented or interacts within a larger signaling network appears to vary in different species. This review will examine the role of ABA in the control of root architecture, focusing on the regulation of lateral root formation in three plant species, Arabidopsis thaliana, Medicago truncatula and Oryza sativa. We will consider how the implementation of the ABA signaling module might be a target of natural selection, to help contribute to the diversity of root architecture in nature. PMID:27135341

  6. 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

    2016-06-01

    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. PMID:27060495

  7. Compartmentation and equilibration of abscisic acid in isolated Xanthium cells

    SciTech Connect

    Bray, E.A.; Zeevaart, J.A.D.

    1986-01-01

    The compartmentation of endogenous abscisic acid (ABA), applied (+/-)-(/sup 3/H)ABA, and (+/-)-trans-ABA was measured in isolated mesophyll cells of the Chicago strain of Xanthium strumarium L. The release of ABA to the medium in the presence or absence of DMSO was used to determine the equilibration of ABA in the cells. It was found that a greater percentage of the (+/-)-(/sup 3/H)ABA and the (+/-)-trans-ABA was released into the medium than of the endogenous ABA, indicating that applied ABA did not equilibrate with the endogenous material. Therefore, in further investigations only the compartmentation of endogenous ABA was studied. Endogenous ABA was released from Xanthium cells according to the pH gradients among the various cellular compartments. Thus, darkness, high external pH, KNO/sub 2/, and drought-stress all increased the efflux of ABA from the cells. Efflux of ABA from the cells in the presence of 0.6 M mannitol occurred within 30 seconds, but only 8% of the endogenous material was released during the 20 minute treatment.

  8. Abscisic Acid: Hidden Architect of Root System Structure.

    PubMed

    Harris, Jeanne M

    2015-01-01

    Plants modulate root growth in response to changes in the local environment, guided by intrinsic developmental genetic programs. The hormone Abscisic Acid (ABA) mediates responses to different environmental factors, such as the presence of nitrate in the soil, water stress and salt, shaping the structure of the root system by regulating the production of lateral roots as well as controlling root elongation by modulating cell division and elongation. Curiously, ABA controls different aspects of root architecture in different plant species, perhaps providing some insight into the great diversity of root architecture in different plants, both from different taxa and from different environments. ABA is an ancient signaling pathway, acquired well before the diversification of land plants. Nonetheless, how this ancient signaling module is implemented or interacts within a larger signaling network appears to vary in different species. This review will examine the role of ABA in the control of root architecture, focusing on the regulation of lateral root formation in three plant species, Arabidopsis thaliana, Medicago truncatula and Oryza sativa. We will consider how the implementation of the ABA signaling module might be a target of natural selection, to help contribute to the diversity of root architecture in nature. PMID:27135341

  9. Structural basis and functions of abscisic acid receptors PYLs

    PubMed Central

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

    2015-01-01

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

  10. Abscisic-acid-induced cellular apoptosis and differentiation in glioma via the retinoid acid signaling pathway.

    PubMed

    Zhou, Nan; Yao, Yu; Ye, Hongxing; Zhu, Wei; Chen, Liang; Mao, Ying

    2016-04-15

    Retinoid acid (RA) plays critical roles in regulating differentiation and apoptosis in a variety of cancer cells. Abscisic acid (ABA) and RA are direct derivatives of carotenoids and share structural similarities. Here we proposed that ABA may also play a role in cellular differentiation and apoptosis by sharing a similar signaling pathway with RA that may be involved in glioma pathogenesis. We reported for the first time that the ABA levels were twofold higher in low-grade gliomas compared with high-grade gliomas. In glioma tissues, there was a positive correlation between the ABA levels and the transcription of cellular retinoic acid-binding protein 2 (CRABP2) and a negative correlation between the ABA levels and transcription of fatty acid-binding protein 5 (FABP5). ABA treatment induced a significant increase in the expression of CRABP2 and a decrease in the expression of peroxisome proliferator-activated receptor (PPAR) in glioblastoma cells. Remarkably, both cellular apoptosis and differentiation were increased in the glioblastoma cells after ABA treatment. ABA-induced cellular apoptosis and differentiation were significantly reduced by selectively silencing RAR-α, while RAR-α overexpression exaggerated the ABA-induced effects. These results suggest that ABA may play a role in the pathogenesis of glioma by promoting cellular apoptosis and differentiation through the RA signaling pathway. PMID:26594836

  11. Involvement of abscisic acid in correlative control of flower abscission in soybean

    SciTech Connect

    Yarrow, G.L.

    1985-01-01

    Studies were carried out in three parts: (1) analysis of endogenous abscisic acid (ABA) in abscising and non-abscising flowers, (2) partitioning of radio-labelled ABA and photoassimilates within the soybean raceme, and (3) shading experiments, wherein endogenous levels, metabolism and partitioning of ABA were determined. Endogenous concentrations of ABA failed to show any consistent relationship to abscission of soybean flowers. Partitioning of radiolabelled ABA and photoassimilates displayed consistently higher sink strengths (% DPM) for both /sup 3/H-ABA and /sup 14/C-photoassimilates for non-abscising flowers than for abscising flowers within control racemes. Shading flowers with aluminum foil, 48 hrs prior to sampling, resulted in lowered endogenous ABA concentrations at 12, 17 and 22 days after anthesis (DAA), but not at 0 or 4 DAA. No differences were found in the catabolism of /sup 3/H-ABA between shaded (abscising) and non-shaded (non-abscising) flowers. Reduced partitioning of ABA and photoassimilates to shaded flowers resulted when shades were applied at 0, 4, 12, and 17 DAA, but not at 22 DAA.

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

    NASA Astrophysics Data System (ADS)

    Meguro, Ayano; Sato, Yutaka

    2014-04-01

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

  13. Leveraging abscisic acid receptors for efficient water use in Arabidopsis

    PubMed Central

    Yang, Zhenyu; Liu, Jinghui; Tischer, Stefanie V.; Christmann, Alexander; Windisch, Wilhelm; Schnyder, Hans; Grill, Erwin

    2016-01-01

    Plant growth requires the influx of atmospheric CO2 through stomatal pores, and this carbon uptake for photosynthesis is inherently associated with a large efflux of water vapor. Under water deficit, plants reduce transpiration and are able to improve carbon for water exchange leading to higher water use efficiency (WUE). Whether increased WUE can be achieved without trade-offs in plant growth is debated. The signals mediating the WUE response under water deficit are not fully elucidated but involve the phytohormone abscisic acid (ABA). ABA is perceived by a family of related receptors known to mediate acclimation responses and to reduce transpiration. We now show that enhanced stimulation of ABA signaling via distinct ABA receptors can result in plants constitutively growing at high WUE in the model species Arabidopsis. WUE was assessed by three independent approaches involving gravimetric analyses, 13C discrimination studies of shoots and derived cellulose fractions, and by gas exchange measurements of whole plants and individual leaves. Plants expressing the ABA receptors RCAR6/PYL12 combined up to 40% increased WUE with high growth rates, i.e., are water productive. Water productivity was associated with maintenance of net carbon assimilation by compensatory increases of leaf CO2 gradients, thereby sustaining biomass acquisition. Leaf surface temperatures and growth potentials of plants growing under well-watered conditions were found to be reliable indicators for water productivity. The study shows that ABA receptors can be explored to generate more plant biomass per water transpired, which is a prime goal for a more sustainable water use in agriculture. PMID:27247417

  14. Leveraging abscisic acid receptors for efficient water use in Arabidopsis.

    PubMed

    Yang, Zhenyu; Liu, Jinghui; Tischer, Stefanie V; Christmann, Alexander; Windisch, Wilhelm; Schnyder, Hans; Grill, Erwin

    2016-06-14

    Plant growth requires the influx of atmospheric CO2 through stomatal pores, and this carbon uptake for photosynthesis is inherently associated with a large efflux of water vapor. Under water deficit, plants reduce transpiration and are able to improve carbon for water exchange leading to higher water use efficiency (WUE). Whether increased WUE can be achieved without trade-offs in plant growth is debated. The signals mediating the WUE response under water deficit are not fully elucidated but involve the phytohormone abscisic acid (ABA). ABA is perceived by a family of related receptors known to mediate acclimation responses and to reduce transpiration. We now show that enhanced stimulation of ABA signaling via distinct ABA receptors can result in plants constitutively growing at high WUE in the model species Arabidopsis WUE was assessed by three independent approaches involving gravimetric analyses, (13)C discrimination studies of shoots and derived cellulose fractions, and by gas exchange measurements of whole plants and individual leaves. Plants expressing the ABA receptors RCAR6/PYL12 combined up to 40% increased WUE with high growth rates, i.e., are water productive. Water productivity was associated with maintenance of net carbon assimilation by compensatory increases of leaf CO2 gradients, thereby sustaining biomass acquisition. Leaf surface temperatures and growth potentials of plants growing under well-watered conditions were found to be reliable indicators for water productivity. The study shows that ABA receptors can be explored to generate more plant biomass per water transpired, which is a prime goal for a more sustainable water use in agriculture. PMID:27247417

  15. Abscisic acid biosynthesis in leaves and roots of Xanthium strumarium

    SciTech Connect

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

    1987-11-01

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

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

    PubMed

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

    2015-04-01

    Abscisic acid (ABA) plays a key role in plant growth and development. The effect of ABA in plants mainly depends on its concentration, which is determined by a balance between biosynthesis and catabolism of ABA. In this study, we characterize a unique UDP-glucosyltransferase (UGT), UGT71C5, which plays an important role in ABA homeostasis by glucosylating ABA to abscisic acid -: glucose ester (GE) in Arabidopsis (Arabidopsis thaliana). Biochemical analyses show that UGT71C5 glucosylates ABA in vitro and in vivo. Mutation of UGT71C5 and down-expression of UGT71C5 in Arabidopsis cause delay in seed germination and enhanced drought tolerance. In contrast, overexpression of UGT71C5 accelerates seed germination and reduces drought tolerance. Determination of the content of ABA and ABA-GE in Arabidopsis revealed that mutation in UGT71C5 and down-expression of UGT71C5 resulted in increased level of ABA and reduced level of ABA-GE, whereas overexpression of UGT71C5 resulted in reduced level of ABA and increased level of ABA-GE. Furthermore, altered levels of ABA in plants lead to changes in transcript abundance of ABA-responsive genes, correlating with the concentration of ABA regulated by UGT71C5 in Arabidopsis. Our work shows that UGT71C5 plays a major role in ABA glucosylation for ABA homeostasis. PMID:25713337

  17. Abscisic Acid Structure-Activity Relationships in Barley Aleurone Layers and Protoplasts (Biological Activity of Optically Active, Oxygenated Abscisic Acid Analogs).

    PubMed Central

    Hill, R. D.; Liu, J. H.; Durnin, D.; Lamb, N.; Shaw, A.; Abrams, S. R.

    1995-01-01

    Optically active forms of abscisic acid (ABA) and their oxygenated metabolites were tested for their biological activity by examining the effects of the compounds on the reversal of gibberellic acid-induced [alpha]-amylase activity in barley (Hordeum vulgare cv Himalaya) aleurone layers and the induction of gene expression in barley aleurone protoplasts transformed with a chimeric construct containing the promoter region of an albumin storage protein gene. Promotion of the albumin storage protein gene response had a more strict stereochemical requirement for elicitation of an ABA response than inhibition of [alpha]-amylase gene expression. The naturally occurring stereoisomer of ABA and its metabolites were more effective at eliciting an ABA-like response. ABA showed the highest activity, followed by 7[prime]-hydroxyABA, with phaseic acid being the least active. Racemic 8[prime]-hydroxy-2[prime],3[prime]-dihydroABA, an analog of 8[prime]-hydroxyABA, was inactive, whereas racemic 2[prime],3[prime]-dihydroABA was as effective as ABA. The differences in response of the same tissue to the ABA enantiomers lead us to conclude that there exists more than one type of ABA receptor and/or multiple signal transduction pathways in barley aleurone tissue. PMID:12228494

  18. Abscisic Acid Structure-Activity Relationships in Barley Aleurone Layers and Protoplasts (Biological Activity of Optically Active, Oxygenated Abscisic Acid Analogs).

    PubMed

    Hill, R. D.; Liu, J. H.; Durnin, D.; Lamb, N.; Shaw, A.; Abrams, S. R.

    1995-06-01

    Optically active forms of abscisic acid (ABA) and their oxygenated metabolites were tested for their biological activity by examining the effects of the compounds on the reversal of gibberellic acid-induced [alpha]-amylase activity in barley (Hordeum vulgare cv Himalaya) aleurone layers and the induction of gene expression in barley aleurone protoplasts transformed with a chimeric construct containing the promoter region of an albumin storage protein gene. Promotion of the albumin storage protein gene response had a more strict stereochemical requirement for elicitation of an ABA response than inhibition of [alpha]-amylase gene expression. The naturally occurring stereoisomer of ABA and its metabolites were more effective at eliciting an ABA-like response. ABA showed the highest activity, followed by 7[prime]-hydroxyABA, with phaseic acid being the least active. Racemic 8[prime]-hydroxy-2[prime],3[prime]-dihydroABA, an analog of 8[prime]-hydroxyABA, was inactive, whereas racemic 2[prime],3[prime]-dihydroABA was as effective as ABA. The differences in response of the same tissue to the ABA enantiomers lead us to conclude that there exists more than one type of ABA receptor and/or multiple signal transduction pathways in barley aleurone tissue. PMID:12228494

  19. Intertissue Signal Transfer of Abscisic Acid from Vascular Cells to Guard Cells1[W

    PubMed Central

    Kuromori, Takashi; Sugimoto, Eriko; Shinozaki, Kazuo

    2014-01-01

    Abscisic acid (ABA) is a phytohormone that responds to environmental stresses, such as water deficiency. Recent studies have shown that ABA biosynthetic enzymes are expressed in the vascular area under both nonstressed and water-stressed growth conditions. However, specific cells in the vasculature involved in ABA biosynthesis have not been identified. Here, we detected the expression of two genes encoding ABA biosynthetic enzymes, ABSCISIC ACID DEFICIENT2 and ABSCISIC ALDEHYDE OXIDASE3, in phloem companion cells in vascular tissues. Furthermore, we identified an ATP-binding cassette transporter, Arabidopsis thaliana ABCG25 (AtABCG25), expressed in the same cells. Additionally, AtABCG25-expressing Spodoptera frugiperda9 culture cells showed an ABA efflux function. Finally, we observed that enhancement of ABA biosynthesis in phloem companion cells induced guard cell responses, even under normal growth conditions. These results show that ABA is synthesized in specific cells and can be transported to target cells in different tissues. PMID:24521878

  20. A Stress-Activated Transposon in Arabidopsis Induces Transgenerational Abscisic Acid Insensitivity.

    PubMed

    Ito, Hidetaka; Kim, Jong-Myong; Matsunaga, Wataru; Saze, Hidetoshi; Matsui, Akihiro; Endo, Takaho A; Harukawa, Yoshiko; Takagi, Hiroki; Yaegashi, Hiroki; Masuta, Yukari; Masuda, Seiji; Ishida, Junko; Tanaka, Maho; Takahashi, Satoshi; Morosawa, Taeko; Toyoda, Tetsuro; Kakutani, Tetsuji; Kato, Atsushi; Seki, Motoaki

    2016-01-01

    Transposable elements (TEs), or transposons, play an important role in adaptation. TE insertion can affect host gene function and provides a mechanism for rapid increases in genetic diversity, particularly because many TEs respond to environmental stress. In the current study, we show that the transposition of a heat-activated retrotransposon, ONSEN, generated a mutation in an abscisic acid (ABA) responsive gene, resulting in an ABA-insensitive phenotype in Arabidopsis, suggesting stress tolerance. Our results provide direct evidence that a transposon activated by environmental stress could alter the genome in a potentially positive manner. Furthermore, the ABA-insensitive phenotype was inherited when the transcription was disrupted by an ONSEN insertion, whereas ABA sensitivity was recovered when the effects of ONSEN were masked by IBM2. These results suggest that epigenetic mechanisms in host plants typically buffered the effect of a new insertion, but could selectively "turn on" TEs when stressed. PMID:26976262

  1. A Stress-Activated Transposon in Arabidopsis Induces Transgenerational Abscisic Acid Insensitivity

    PubMed Central

    Ito, Hidetaka; Kim, Jong-Myong; Matsunaga, Wataru; Saze, Hidetoshi; Matsui, Akihiro; Endo, Takaho A.; Harukawa, Yoshiko; Takagi, Hiroki; Yaegashi, Hiroki; Masuta, Yukari; Masuda, Seiji; Ishida, Junko; Tanaka, Maho; Takahashi, Satoshi; Morosawa, Taeko; Toyoda, Tetsuro; Kakutani, Tetsuji; Kato, Atsushi; Seki, Motoaki

    2016-01-01

    Transposable elements (TEs), or transposons, play an important role in adaptation. TE insertion can affect host gene function and provides a mechanism for rapid increases in genetic diversity, particularly because many TEs respond to environmental stress. In the current study, we show that the transposition of a heat-activated retrotransposon, ONSEN, generated a mutation in an abscisic acid (ABA) responsive gene, resulting in an ABA-insensitive phenotype in Arabidopsis, suggesting stress tolerance. Our results provide direct evidence that a transposon activated by environmental stress could alter the genome in a potentially positive manner. Furthermore, the ABA-insensitive phenotype was inherited when the transcription was disrupted by an ONSEN insertion, whereas ABA sensitivity was recovered when the effects of ONSEN were masked by IBM2. These results suggest that epigenetic mechanisms in host plants typically buffered the effect of a new insertion, but could selectively “turn on” TEs when stressed. PMID:26976262

  2. Movement of abscisic acid into the apoplast in response to water stress in Xanthium strumarium L

    SciTech Connect

    Cornish, K.; Zeevaart, J.A.D.

    1985-07-01

    The effect of water stress on the redistribution of abscisic acid (ABA) in mature leaves of Xanthium strumarium L. was investigated using a pressure dehydration technique. In both turgid and stressed leaves, the ABA in the xylem exudate, the apoplastic ABA, increased before bulk leaf stress-induced ABA accumulation began. In the initially turgid leaves, the ABA level remained constant in both the apoplast and the leaf as a whole until wilting symptoms appeared. Following turgor loss, sufficient quantities of ABA moved into the apoplast to stimulate stomatal closure. Thus, the initial increase of apoplastic ABA may be relevant to the rapid stomatal closure seen in stressed leaves before their bulk leaf ABA levels rise. Following recovery from water stress, elevated levels of ABA remained in the apoplast after the bulk leaf contents had returned to their prestress values. This apoplastic ABA may retard stomatal reopening during the initial recovery period. 32 references, 5 figures.

  3. 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...

  4. Specific domain structures control abscisic acid-, salicylic acid-, and stress-mediated SIZ1 phenotypes.

    PubMed

    Cheong, Mi Sun; Park, Hyeong Cheol; Hong, Mi Ju; Lee, Jiyoung; Choi, Wonkyun; Jin, Jing Bo; Bohnert, Hans J; Lee, Sang Yeol; Bressan, Ray A; Yun, Dae-Jin

    2009-12-01

    SIZ1 (for yeast SAP and MIZ1) encodes the sole ortholog of mammalian PIAS (for protein inhibitor of activated STAT) and yeast SIZ SUMO (for small ubiquitin-related modifier) E3 ligases in Arabidopsis (Arabidopsis thaliana). Four conserved motifs in SIZ1 include SAP (for scaffold attachment factor A/B/acinus/PIAS domain), PINIT (for proline-isoleucine-asparagine-isoleucine-threonine), SP-RING (for SIZ/PIAS-RING), and SXS (for serine-X-serine, where X is any amino acid) motifs. SIZ1 contains, in addition, a PHD (for plant homeodomain) typical of plant PIAS proteins. We determined phenotypes of siz1-2 knockout mutants transformed with SIZ1 alleles carrying point mutations in the predicted domains. Domain SP-RING is required for SUMO conjugation activity and nuclear localization of SIZ1. Salicylic acid (SA) accumulation and SA-dependent phenotypes of siz1-2, such as diminished plant size, heightened innate immunity, and abscisic acid inhibition of cotyledon greening, as well as SA-independent basal thermotolerance were not complemented by the altered SP-RING allele of SIZ1. The SXS domain also controlled SA accumulation and was involved in greening and expansion of cotyledons of seedlings germinated in the presence of abscisic acid. Mutations of the PHD zinc finger domain and the PINIT motif affected in vivo SUMOylation. Expression of the PHD and/or PINIT domain mutant alleles of SIZ1 in siz1-2 promoted hypocotyl elongation in response to sugar and light. The various domains of SIZ1 make unique contributions to the plant's ability to cope with its environment. PMID:19837819

  5. Molecular characterization of carotenoid cleavage dioxygenases and the effect of gibberellin, abscisic acid, and sodium chloride on the expression of genes involved in the carotenoid biosynthetic pathway and carotenoid accumulation in the callus of Scutellaria baicalensis Georgi.

    PubMed

    Tuan, Pham Anh; Kim, Jae Kwang; Lee, Sanghyun; Chae, Soo Cheon; Park, Sang Un

    2013-06-12

    Three cDNAs encoding carotenoid cleavage dioxygenases (SbCCD1, SbCCD4, and SbNCED) were isolated from Scutellaria baicalensis , an important traditional herb in Asia and North America. Amino acid sequence alignments showed that they share high identity and similarity to their orthologs in other plant species. Quantitative real-time polymerase chain reaction analysis revealed that SbCCD1 and SbCCD4 were most strongly expressed in flowers, whereas SbNCED was expressed at the highest level in roots. The expression levels of phytoene synthase (SbPSY), phytoene desaturase (SbPDS), ξ-carotene desaturase (SbZDS), β-ring carotene hydroxylase (SbCHXB), zeaxanthin epoxidase (SbZEP), SbCCD1, SbCCD4, and SbNCED in the callus of S. baicalensis varied under different concentrations of gibberellic acid (GA3) and abscisic acid (ABA). Under NaCl treatment, expression levels of all genes increased with increasing NaCl concentrations. Except for zeaxanthin, increasing GA3, ABA, and NaCl concentrations caused higher losses in the total carotenoid content. The total carotenoid content substantially decreased with increasing GA3, ABA, and NaCl concentrations, with the biggest reductions observed in the NaCl treatment. The isolation and characterization of SbCCD1, SbCCD4, and SbNCED together with the study on the effect of GA3, ABA, and NaCl on carotenoid biosynthesis will be helpful to elucidate the carotenoid biosynthesis mechanism in S. baicalensis and may set new trends in metabolic engineering of carotenoids in plants. PMID:23683071

  6. Control of Abscisic Acid Catabolism and Abscisic Acid Homeostasis Is Important for Reproductive Stage Stress Tolerance in Cereals1[W][OA

    PubMed Central

    Ji, Xuemei; Dong, Baodi; Shiran, Behrouz; Talbot, Mark J.; Edlington, Jane E.; Hughes, Trijntje; White, Rosemary G.; Gubler, Frank; Dolferus, Rudy

    2011-01-01

    Drought stress at the reproductive stage causes pollen sterility and grain loss in wheat (Triticum aestivum). Drought stress induces abscisic acid (ABA) biosynthesis genes in anthers and ABA accumulation in spikes of drought-sensitive wheat varieties. In contrast, drought-tolerant wheat accumulates lower ABA levels, which correlates with lower ABA biosynthesis and higher ABA catabolic gene expression (ABA 8′-hydroxylase). Wheat TaABA8′OH1 deletion lines accumulate higher spike ABA levels and are more drought sensitive. ABA treatment of the spike mimics the effect of drought, causing high levels of sterility. ABA treatment represses the anther cell wall invertase gene TaIVR1, and drought-tolerant lines appeared to be more sensitive to the effect of ABA. Drought-induced sterility shows similarity to cold-induced sterility in rice (Oryza sativa). In cold-stressed rice, the rate of ABA accumulation was similar in cold-sensitive and cold-tolerant lines during the first 8 h of cold treatment, but in the tolerant line, ABA catabolism reduced ABA levels between 8 and 16 h of cold treatment. The ABA biosynthesis gene encoding 9-cis-epoxycarotenoid dioxygenase in anthers is mainly expressed in parenchyma cells surrounding the vascular bundle of the anther. Transgenic rice lines expressing the wheat TaABA8′OH1 gene under the control of the OsG6B tapetum-specific promoter resulted in reduced anther ABA levels under cold conditions. The transgenic lines showed that anther sink strength (OsINV4) was maintained under cold conditions and that this correlated with improved cold stress tolerance. Our data indicate that ABA and ABA 8′-hydroxylase play an important role in controlling anther ABA homeostasis and reproductive stage abiotic stress tolerance in cereals. PMID:21502188

  7. The basic leucine zipper transcription factor ABSCISIC ACID RESPONSE ELEMENT-BINDING FACTOR2 is an important transcriptional regulator of abscisic acid-dependent grape berry ripening processes.

    PubMed

    Nicolas, Philippe; Lecourieux, David; Kappel, Christian; Cluzet, Stéphanie; Cramer, Grant; Delrot, Serge; Lecourieux, Fatma

    2014-01-01

    In grape (Vitis vinifera), abscisic acid (ABA) accumulates during fruit ripening and is thought to play a pivotal role in this process, but the molecular basis of this control is poorly understood. This work characterizes ABSCISIC ACID RESPONSE ELEMENT-BINDING FACTOR2 (VvABF2), a grape basic leucine zipper transcription factor belonging to a phylogenetic subgroup previously shown to be involved in ABA and abiotic stress signaling in other plant species. VvABF2 transcripts mainly accumulated in the berry, from the onset of ripening to the harvesting stage, and were up-regulated by ABA. Microarray analysis of transgenic grape cells overexpressing VvABF2 showed that this transcription factor up-regulates and/or modifies existing networks related to ABA responses. In addition, grape cells overexpressing VvABF2 exhibited enhanced responses to ABA treatment compared with control cells. Among the VvABF2-mediated responses highlighted in this study, the synthesis of phenolic compounds and cell wall softening were the most strongly affected. VvABF2 overexpression strongly increased the accumulation of stilbenes that play a role in plant defense and human health (resveratrol and piceid). In addition, the firmness of fruits from tomato (Solanum lycopersicum) plants overexpressing VvABF2 was strongly reduced. These data indicate that VvABF2 is an important transcriptional regulator of ABA-dependent grape berry ripening. PMID:24276949

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

    NASA Technical Reports Server (NTRS)

    Moore, R.

    1990-01-01

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

  9. Functional convergence of oxylipin and abscisic acid pathways controls stomatal closure in response to drought.

    PubMed

    Savchenko, Tatyana; Kolla, Venkat A; Wang, Chang-Quan; Nasafi, Zainab; Hicks, Derrick R; Phadungchob, Bpantamars; Chehab, Wassim E; Brandizzi, Federica; Froehlich, John; Dehesh, Katayoon

    2014-03-01

    Membranes are primary sites of perception of environmental stimuli. Polyunsaturated fatty acids are major structural constituents of membranes that also function as modulators of a multitude of signal transduction pathways evoked by environmental stimuli. Different stresses induce production of a distinct blend of oxygenated polyunsaturated fatty acids, "oxylipins." We employed three Arabidopsis (Arabidopsis thaliana) ecotypes to examine the oxylipin signature in response to specific stresses and determined that wounding and drought differentially alter oxylipin profiles, particularly the allene oxide synthase branch of the oxylipin pathway, responsible for production of jasmonic acid (JA) and its precursor 12-oxo-phytodienoic acid (12-OPDA). Specifically, wounding induced both 12-OPDA and JA levels, whereas drought induced only the precursor 12-OPDA. Levels of the classical stress phytohormone abscisic acid (ABA) were also mainly enhanced by drought and little by wounding. To explore the role of 12-OPDA in plant drought responses, we generated a range of transgenic lines and exploited the existing mutant plants that differ in their levels of stress-inducible 12-OPDA but display similar ABA levels. The plants producing higher 12-OPDA levels exhibited enhanced drought tolerance and reduced stomatal aperture. Furthermore, exogenously applied ABA and 12-OPDA, individually or combined, promote stomatal closure of ABA and allene oxide synthase biosynthetic mutants, albeit most effectively when combined. Using tomato (Solanum lycopersicum) and Brassica napus verified the potency of this combination in inducing stomatal closure in plants other than Arabidopsis. These data have identified drought as a stress signal that uncouples the conversion of 12-OPDA to JA and have revealed 12-OPDA as a drought-responsive regulator of stomatal closure functioning most effectively together with ABA. PMID:24429214

  10. Plastid Located WHIRLY1 Enhances the Responsiveness of Arabidopsis Seedlings Toward Abscisic Acid

    PubMed Central

    Isemer, Rena; Krause, Kirsten; Grabe, Nils; Kitahata, Nobutaka; Asami, Tadao; Krupinska, Karin

    2012-01-01

    WHIRLY1 is a protein that can be translocated from the plastids to the nucleus, making it an ideal candidate for communicating information between these two compartments. Mutants of Arabidopsis thaliana lacking WHIRLY1 (why1) were shown to have a reduced sensitivity toward salicylic acid (SA) and abscisic acid (ABA) during germination. Germination assays in the presence of abamine, an inhibitor of ABA biosynthesis, revealed that the effect of SA on germination was in fact caused by a concomitant stimulation of ABA biosynthesis. In order to distinguish whether the plastid or the nuclear isoform of WHIRLY1 is adjusting the responsiveness toward ABA, sequences encoding either the complete WHIRLY1 protein or a truncated form lacking the plastid transit peptide were overexpressed in the why1 mutant background. In plants overexpressing the full-length sequence, WHIRLY1 accumulated in both plastids and the nucleus, whereas in plants overexpressing the truncated sequence, WHIRLY1 accumulated exclusively in the nucleus. Seedlings containing recombinant WHIRLY1 in both compartments were hypersensitive toward ABA. In contrast, seedlings possessing only the nuclear form of WHIRLY1 were as insensitive toward ABA as the why1 mutants. ABA was furthermore shown to lower the rate of germination of wildtype seeds even in the presence of abamine which is known to inhibit the formation of xanthoxin, the plastid located precursor of ABA. From this we conclude that plastid located WHIRLY1 enhances the responsiveness of seeds toward ABA even when ABA is supplied exogenously. PMID:23269926

  11. Sucrose Loading in Isolated Veins of Pisum sativum: Regulation by Abscisic Acid, Gibberellic Acid, and Cell Turgor.

    PubMed

    Estruch, J J; Peretó, J G; Vercher, Y; Beltrán, J P

    1989-09-01

    Enzymatically isolated vein networks from mature pea (Pisum sativum L. cv Alaska) leaves were employed to investigate the properties of sucrose loading and the effect of phytohormones and cell turgor on this process. The sucrose uptake showed two components: a saturable and a first-order kinetics system. The high affinity system (K(m), 3.3 millimolar) was located at the plasmalemma (p-chloromercuriphenylsulfonic acid and orthovanadate sensitivity). Further characterization of this system, including pH dependence and effects of energy metabolism inhibitors, supported the H(+)-sugar symport concept for sucrose loading. Within a physiological range (0.1-100 micromolar) and after 90 min, abscisic acid (ABA) inhibited and gibberellic acid (GA(3)) promoted 1 millimolar sucrose uptake. These responses were partially (ABA) or totally (GA(3)) turgor-dependent. In experiments of combined hormonal treatments, ABA counteracted the GA(3) positive effects on sucrose uptake. The abolishment of these responses by p-chloromercuriphenylsulfonic acid and experiments on proton flux suggest that both factors (cell turgor and hormones) are modulating the H(+) ATPase plasmalemma activity. The results are discussed in terms of their physiological relevance. PMID:16667007

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

    PubMed

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

    2015-02-01

    Sunflower (Helianthus annuus L.) seed dormancy is regulated by reactive oxygen species (ROS) and can be alleviated by incubating dormant embryos in the presence of methylviologen (MV), a ROS-generating compound. Ethylene alleviates sunflower seed dormancy whereas abscisic acid (ABA) represses germination. The purposes of this study were to identify the molecular basis of ROS effect on seed germination and to investigate their possible relationship with hormone signalling pathways. Ethylene treatment provoked ROS generation in embryonic axis whereas ABA had no effect on their production. The beneficial effect of ethylene on germination was lowered in the presence of antioxidant compounds, and MV suppressed the inhibitory effect of ABA. MV treatment did not alter significantly ethylene nor ABA production during seed imbibition. Microarray analysis showed that MV treatment triggered differential expression of 120 probe sets (59 more abundant and 61 less abundant genes), and most of the identified transcripts were related to cell signalling components. Many transcripts less represented in MV-treated seeds were involved in ABA signalling, thus suggesting an interaction between ROS and ABA signalling pathways at the transcriptional level. Altogether, these results shed new light on the crosstalk between ROS and plant hormones in seed germination. PMID:24811898

  13. Stomatal response to abscisic Acid is a function of current plant water status.

    PubMed

    Tardieu, F; Davies, W J

    1992-02-01

    We investigated, under laboratory and field conditions, the possibility that increasing abscisic acid (ABA) concentrations and decreasing water potentials can interact in their effects on stomata. One experiment was carried out with epidermal pieces of Commelina communis incubated in media with a variety of ABA and polyethylene glycol concentrations. In the media without ABA, incubation in solutions with water potentials between -0.3 and -1.5 megapascals had no significant effect on stomatal aperture. Conversely, the sensitivity of stomatal aperture to ABA was trebled in solutions at -1.5 megapascals compared with sensitivity at -0.3 megapascals. The effect of the change in sensitivity was more important than the absolute effect of ABA at the highest water potential. In a field experiment, sensitivity of maize stomatal conductance to the concentration of ABA in the xylem sap varied strongly with the time of the day. We consider that the most likely explanation for this is the influence of a change in leaf or epidermal water potential that accompanies an increase in irradiance and saturation deficit as the day progresses. These observations suggest that epidermal water relations may act as a modulator of the responses of stomata to ABA. We argue that such changes must be taken into account in studies or modeling of plant responses to drought stress. PMID:16668674

  14. Abscisic Acid Control of rbcS and cab Transcription in Tomato Leaves.

    PubMed

    Bartholomew, D M; Bartley, G E; Scolnik, P A

    1991-05-01

    Leaves of tomato (Lycopersicon esculentum) plants grown in soil in which moisture was lowered from field capacity to levels approaching permanent wilting point show a 10-fold increase in abscisic acid (ABA) and a 60 to 70 percent decrease in rbcS and cab steady-state mRNA levels. As indicated by transcription run-on experiments, the effect occurs primarily at the transcriptional level. Similar water deficit had only a minor effect on ABA level and on rbcS and cab expression in leaves of sitiens, an ABA mutant of tomato. Expression of rbcL, the chloroplast gene coding for the large subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase, is not affected by water stress. Application of exogenous ABA results in decreased rbcS and cab expression in both wild-type and sitiens leaves. Analysis of the expression of individual members of the rbcS gene family indicates that under water-deficit conditions, expression derives primarily from only three of the five rbcS genes. Effects of dark adaptation and water deficit are additive for cab but not for rbcS expression. These results support the hypothesis that, at least under water-deficit conditions, ABA or a derivative thereof mediates a negative regulation of rbcS and cab transcription in tomato plants. PMID:16668167

  15. Modulation of the nitrate reductase transcript by cytokinin and abscisic acid in etiolated barley seedlings

    SciTech Connect

    Lu, Jia-ling; Enl, J.R.; Chen, Chong-maw )

    1989-04-01

    To investigate the molecular mechanism of the hormonal modulation of nitrate reductase (NR) activity, the influence of benzyladenine (BA) and/or abscisic acid (ABA) on the level of NR poly(A)RNA was studied in etiolated barley seedlings using a {sup 32}P-labelled NR cDNA as a probe. Enhancement of NR activity by 2 {times} 10{sup {minus}5}M BA was measurable only after 60 minutes of exposure of the seedlings to light, while a significant stimulatory effect on the transcript level could by clearly detected within 15 minutes. Northern blot analyses of the levels of NR poly(A)RNA indicate that the amount present is proportional to the concentration of BA applied to the seedlings. The stimulatory effects seen for BA were nullified by ABA. The counteractive effects of ABA on BA were dose-responsive, with greater inhibition at higher concentrations of ABA. Evidence suggests that the interaction of BA and ABA on NR activity is at the transcriptional level, however, is also possible that interactions occur at the postranscriptional level as well.

  16. Auxin-Induced Ethylene Triggers Abscisic Acid Biosynthesis and Growth Inhibition1

    PubMed Central

    Hansen, Hauke; Grossmann, Klaus

    2000-01-01

    The growth-inhibiting effects of indole-3-acetic acid (IAA) at high concentration and the synthetic auxins 7-chloro-3-methyl-8-quinolinecarboxylic acid (quinmerac), 2-methoxy-3,6-dichlorobenzoic acid (dicamba), 4-amino-3,6,6-trichloropicolinic acid (picloram), and naphthalene acetic acid, were investigated in cleavers (Galium aparine). When plants were root treated with 0.5 mm IAA, shoot epinasty and inhibition of root and shoot growth developed during 24 h. Concomitantly, 1-aminocyclopropane-1-carboxylic acid (ACC) synthase activity, and ACC and ethylene production were transiently stimulated in the shoot tissue within 2 h, followed by increases in immunoreactive (+)-abscisic acid (ABA) and its precursor xanthoxal (xanthoxin) after 5 h. After 24 h of treatment, levels of xanthoxal and ABA were elevated up to 2- and 24-fold, relative to control, respectively. In plants treated with IAA, 7-chloro-3-methyl-8-quinolinecarboxylic acid, naphthalene acetic acid, 2-methoxy-3,6-dichlorobenzoic acid, and 4-amino-3,6,6-trichloropicolinic acid, levels of ethylene, ACC, and ABA increased in close correlation with inhibition of shoot growth. Aminoethoxyvinyl-glycine and cobalt ions, which inhibit ethylene synthesis, decreased ABA accumulation and growth inhibition, whereas the ethylene-releasing ethephon promoted ABA levels and growth inhibition. In accordance, tomato mutants defective in ethylene perception (never ripe) did not produce the xanthoxal and ABA increases and growth inhibition induced by auxins in wild-type plants. This suggests that auxin-stimulated ethylene triggers ABA accumulation and the consequent growth inhibition. Reduced catabolism most probably did not contribute to ABA increase, as indicated by immunoanalyses of ABA degradation and conjugation products in shoot tissue and by pulse experiments with [3H]-ABA in cell suspensions of G. aparine. In contrast, studies using inhibitors of ABA biosynthesis (fluridone, naproxen, and tungstate), ABA

  17. Induction of Crassulacean Acid Metabolism in the Facultative Halophyte Mesembryanthemum crystallinum by Abscisic Acid 1

    PubMed Central

    Chu, Chun; Dai, Ziyu; Ku, Maurice S. B.; Edwards, Gerald E.

    1990-01-01

    The facultative halophyte, Mesembryanthemum crystallinum, shifts its mode of carbon assimilation from the C3 pathway to Crassulacean acid metabolism (CAM) in response to water stress. In this study, exogenously applied abscisic acid (ABA), at micromolar concentrations, could partially substitute for water stress in induction of CAM in this species. ABA at concentrations of 5 to 10 micromolar, when applied to leaves or to the roots in hydroponic culture or in soil, induced the expression of CAM within days (as indicated by the nocturnal accumulation of total titratable acidity and malate). After applying ABA there was also an increase in phosphoenolpyruvate carboxylase and NADP-malic enzyme activities. The degree and time course of induction by ABA were comparable to those induced by salt and water stress. Electrophoretic analyses of leaf soluble protein indicate that the increases in phosphoenolpyruvate carboxylase activity during the induction by ABA, salt, and water stress are due to an increase in the quantity of the enzyme protein. ABA may be a factor in the stress-induced expression of CAM in M. crystallinum, serving as a functional link between stress and biochemical adaptation. Images Figure 9 PMID:16667587

  18. Postharvest Exogenous Application of Abscisic Acid Reduces Internal Browning in Pineapple.

    PubMed

    Zhang, Qin; Liu, Yulong; He, Congcong; Zhu, Shijiang

    2015-06-10

    Internal browning (IB) is a postharvest physiological disorder causing economic losses in pineapple, but there is no effective control measure. In this study, postharvest application of 380 μM abscisic acid (ABA) reduced IB incidence by 23.4-86.3% and maintained quality in pineapple fruit. ABA reduced phenolic contents and polyphenol oxidase and phenylalanine ammonia lyase activities; increased catalase and peroxidase activities; and decreased O2(·-), H2O2, and malondialdehyde levels. This suggests ABA could control IB through inhibiting phenolics biosynthesis and oxidation and enhancing antioxidant capability. Furthermore, the efficacy of IB control by ABA was not obviously affected by tungstate, ABA biosynthesis inhibitor, nor by diphenylene iodonium, NADPH oxidase inhibitor, nor by lanthanum chloride, calcium channel blocker, suggesting that ABA is sufficient for controlling IB. This process might not involve H2O2 generation, but could involve the Ca(2+) channels activation. These results provide potential for developing effective measures for controlling IB in pineapple. PMID:26007196

  19. Abscisic Acid Negatively Regulates Elicitor-Induced Synthesis of Capsidiol in Wild Tobacco1[W

    PubMed Central

    Mialoundama, Alexis Samba; Heintz, Dimitri; Debayle, Delphine; Rahier, Alain; Camara, Bilal; Bouvier, Florence

    2009-01-01

    In the Solanaceae, biotic and abiotic elicitors induce de novo synthesis of sesquiterpenoid stress metabolites known as phytoalexins. Because plant hormones play critical roles in the induction of defense-responsive genes, we have explored the effect of abscisic acid (ABA) on the synthesis of capsidiol, the major wild tobacco (Nicotiana plumbaginifolia) sesquiterpenoid phytoalexin, using wild-type plants versus nonallelic mutants Npaba2 and Npaba1 that are deficient in ABA synthesis. Npaba2 and Npaba1 mutants exhibited a 2-fold higher synthesis of capsidiol than wild-type plants when elicited with either cellulase or arachidonic acid or when infected by Botrytis cinerea. The same trend was observed for the expression of the capsidiol biosynthetic genes 5-epi-aristolochene synthase and 5-epi-aristolochene hydroxylase. Treatment of wild-type plants with fluridone, an inhibitor of the upstream ABA pathway, recapitulated the behavior of Npaba2 and Npaba1 mutants, while the application of exogenous ABA reversed the enhanced synthesis of capsidiol in Npaba2 and Npaba1 mutants. Concomitant with the production of capsidiol, we observed the induction of ABA 8′-hydroxylase in elicited plants. In wild-type plants, the induction of ABA 8′-hydroxylase coincided with a decrease in ABA content and with the accumulation of ABA catabolic products such as phaseic acid and dihydrophaseic acid, suggesting a negative regulation exerted by ABA on capsidiol synthesis. Collectively, our data indicate that ABA is not required per se for the induction of capsidiol synthesis but is essentially implicated in a stress-response checkpoint to fine-tune the amplification of capsidiol synthesis in challenged plants. PMID:19420326

  20. Abscisic Acid Stimulates a Calcium-Dependent Protein Kinase in Grape Berry1[W

    PubMed Central

    Yu, Xiang-Chun; Li, Mei-Jun; Gao, Gui-Feng; Feng, Hai-Zhong; Geng, Xue-Qing; Peng, Chang-Cao; Zhu, Sai-Yong; Wang, Xiao-Jing; Shen, Yuan-Yue; Zhang, Da-Peng

    2006-01-01

    It has been demonstrated that calcium plays a central role in mediating abscisic acid (ABA) signaling, but many of the Ca2+-binding sensory proteins as the components of the ABA-signaling pathway remain to be elucidated. Here we identified, characterized, and purified a 58-kD ABA-stimulated calcium-dependent protein kinase from the mesocarp of grape berries (Vitis vinifera × Vitis labrusca), designated ACPK1 (for ABA-stimulated calcium-dependent protein kinase1). ABA stimulates ACPK1 in a dose-dependent manner, and the ACPK1 expression and enzyme activities alter accordantly with the endogenous ABA concentrations during fruit development. The ABA-induced ACPK1 stimulation appears to be transient with a rapid effect in 15 min but also with a slow and steady state of induction after 60 min. ABA acts on ACPK1 indirectly and dependently on in vivo state of the tissues. Two inactive ABA isomers, (−)-2-cis, 4-trans-ABA and 2-trans, 4-trans-(±)-ABA, are ineffective for inducing ACPK1 stimulation, revealing that the ABA-induced effect is stereo specific to physiological active (+)-2-cis, 4-trans-ABA. The other phytohormones such as auxin indoleacetic acid, gibberellic acid, synthetic cytokinin N-benzyl-6-aminopurine, and brassinolide are also ineffective in this ACPK1 stimulation. Based on sequencing of the two-dimensional electrophoresis-purified ACPK1, we cloned the ACPK1 gene. The ACPK1 is expressed specifically in grape berry covering a fleshy portion and seeds, and in a developmental stage-dependent manner. We further showed that ACPK1 is localized in both plasma membranes and chloroplasts/plastids and positively regulates plasma membrane H+-ATPase in vitro, suggesting that ACPK1 may be involved in the ABA-signaling pathway. PMID:16407437

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

    PubMed

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

    2015-09-01

    Environmental stresses are effective triggers for the biosynthesis of various secondary metabolites in plants, and phytohormones such as jasmonic acid and abscisic acid are known to mediate such responses in flowering plants. However, the detailed mechanism underlying the regulation of secondary metabolism in bryophytes remains unclear. In this study, the induction mechanism of secondary metabolites in the model liverwort Marchantia polymorpha was investigated. Abscisic acid (ABA) and ultraviolet irradiation (UV-C) were found to induce the biosynthesis of isoriccardin C, marchantin C, and riccardin F, which are categorized as bisbibenzyls, characteristic metabolites of liverworts. UV-C led to the significant accumulation of ABA. Overexpression of MpABI1, which encodes protein phosphatase 2C (PP2C) as a negative regulator of ABA signaling, suppressed accumulation of bisbibenzyls in response to ABA and UV-C irradiation and conferred susceptibility to UV-C irradiation. These data show that ABA plays a significant role in the induction of bisbibenzyl biosynthesis, which might confer tolerance against UV-C irradiation in M. polymorpha. PMID:26055979

  2. Abscisic acid regulation of DC8, a carrot embryonic gene. [Daucus carota

    SciTech Connect

    Hatzopoulos, P.; Fong, F.; Sung, Z.R. Texas A M Univ., College Station )

    1990-10-01

    DC8 encodes a hydrophylic 66 kilodalton protein located in the cytoplasm and cell walls of carrot (Daucus carota) embryo and endosperm. During somatic embryogenesis, the levels of DC8 mRNA and protein begin to increase 5 days after removal of auxin. To study the role of abscisic acid (ABA) in the regulation of DC8 gene, fluridone, 1-methyl-3-phenyl,-5(3-trifluoro-methyl-phenyl)-4(1H)-pyridinone, was used to inhibit the endogenous ABA content of the embryos. Fluridone, 50 micrograms per milliliter, effectively inhibits the accumulation of ABA in globular-tage embryos. Western and Northern analysis show that when fluridone is added to the culture medium DC8 protein and mRNA decrease to very low levels. ABA added to fluridone supplemented culture media restores the DC8 protein and mRNA to control levels. Globular-stage embryos contain 0.9 to 1.4 {times} 10{sup {minus}7} molar ABA while 10{sup {minus}6} molar exogenously supplied ABA is the optimal concentration for restoration of DC8 protein accumulation in fluridone-treated embryos. The mRNA level is increased after 15 minutes of ABA addition and reaches maximal levels by 60 minutes. Evidence is presented that, unlike other ABA-regulated genes, DC8 is not induced in nonembryonic tissues via desiccation nor addition of ABA.

  3. (+)-Abscisic Acid 8′-Hydroxylase Is a Cytochrome P450 Monooxygenase1

    PubMed Central

    Krochko, Joan E.; Abrams, Garth D.; Loewen, Mary K.; Abrams, Suzanne R.; Cutler, Adrian J.

    1998-01-01

    Abscisic acid (ABA) 8′-hydroxylase catalyzes the first step in the oxidative degradation of (+)-ABA. The development of a robust in vitro assay has now permitted detailed examination and characterization of this enzyme. Although several factors (buffer, cofactor, and source tissue) were critical in developing the assay, the most important of these was the identification of a tissue displaying high amounts of in vivo enzyme activity (A.J. Cutler, T.M. Squires, M.K. Loewen, J.J. Balsevich [1997] J Exp Bot 48: 1787–1795). (+)-ABA 8′-hydroxylase is an integral membrane protein that is localized to the microsomal fraction in suspension-cultured maize (Zea mays) cells. (+)-ABA metabolism requires both NADPH and molecular oxygen. NADH was not an effective cofactor, although there was substantial stimulation of activity (synergism) when it was included at rate-limiting NADPH concentrations. The metabolism of (+)-ABA was progressively inhibited at O2 concentrations less than 10% (v/v) and was very low (less than 5% of control) under N2. (+)-ABA 8′-hydroxylase activity was inhibited by tetcyclacis (50% inhibition at 10−6 m), cytochrome c (oxidized form), and CO. The CO inhibition was reversible by light from several regions of the visible spectrum, but most efficiently by blue and amber light. These data strongly support the contention that (+)-ABA 8′-hydroxylase is a cytochrome P450 monooxygenase. PMID:9808729

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

    SciTech Connect

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

    1985-01-01

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

  5. Abscisic Acid Analogues That Act as Universal or Selective Antagonists of Phytohormone Receptors.

    PubMed

    Rajagopalan, Nandhakishore; Nelson, Ken M; Douglas, Amy F; Jheengut, Vishal; Alarcon, Idralyn Q; McKenna, Sean A; Surpin, Marci; Loewen, Michele C; Abrams, Suzanne R

    2016-09-13

    The plant hormone abscisic acid (ABA) plays many important roles in controlling plant development and physiology, from flowering to senescence. ABA is now known to exert its effects through a family of soluble ABA receptors, which in Arabidopsis thaliana has 13 members divided into three clades. Homologues of these receptors are present in other plants, also in relatively large numbers. Investigation of the roles of each homologue in mediating the diverse physiological roles of ABA is hampered by this genetic redundancy. We report herein the in vitro screening of a targeted ABA-like analogue library and identification of novel antagonist hits, including the analogue PBI686 that had been developed previously as a probe for identifying ABA-binding proteins. Further in vitro characterization of PBI686 and development of second-generation leads yielded both receptor-selective and universal antagonist hits. In planta assays in different species have demonstrated that these antagonist leads can overcome various ABA-induced physiological changes. While the general antagonists open up a hitherto unexplored avenue for controlling plant growth through inhibition of ABA-regulated physiological processes, the receptor-selective antagonist can be developed into chemical probes to explore the physiological roles of individual receptors. PMID:27523384

  6. Crucial Roles of Abscisic Acid Biogenesis in Virulence of Rice Blast Fungus Magnaporthe oryzae

    PubMed Central

    Spence, Carla A.; Lakshmanan, Venkatachalam; Donofrio, Nicole; Bais, Harsh P.

    2015-01-01

    Rice suffers dramatic yield losses due to blast pathogen Magnaporthe oryzae. Pseudomonas chlororaphis EA105, a bacterium that was isolated from the rice rhizosphere, inhibits M. oryzae. It was shown previously that pre-treatment of rice with EA105 reduced the size of blast lesions through jasmonic acid (JA)- and ethylene (ETH)-mediated ISR. Abscisic acid (ABA) acts antagonistically toward salicylic acid (SA), JA, and ETH signaling, to impede plant defense responses. EA105 may be reducing the virulence of M. oryzae by preventing the pathogen from up-regulating the key ABA biosynthetic gene NCED3 in rice roots, as well as a β-glucosidase likely involved in activating conjugated inactive forms of ABA. However, changes in total ABA concentrations were not apparent, provoking the question of whether ABA concentration is an indicator of ABA signaling and response. In the rice-M. oryzae interaction, ABA plays a dual role in disease severity by increasing plant susceptibility and accelerating pathogenesis in the fungus itself. ABA is biosynthesized by M. oryzae. Further, exogenous ABA increased spore germination and appressoria formation, distinct from other plant growth regulators. EA105, which inhibits appressoria formation, counteracted the virulence-promoting effects of ABA on M. oryzae. The role of endogenous fungal ABA in blast disease was confirmed through the inability of a knockout mutant impaired in ABA biosynthesis to form lesions on rice. Therefore, it appears that EA105 is invoking multiple strategies in its protection of rice from blast including direct mechanisms as well as those mediated through plant signaling. ABA is a molecule that is likely implicated in both tactics. PMID:26648962

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

    PubMed

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

    2016-02-01

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

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

    PubMed Central

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

    2016-01-01

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

  9. Abscisic Acid Induction of Vacuolar H+-ATPase Activity in Mesembryanthemum crystallinum Is Developmentally Regulated1

    PubMed Central

    Barkla, Bronwyn J.; Vera-Estrella, Rosario; Maldonado-Gama, Minerva; Pantoja, Omar

    1999-01-01

    Abscisic acid (ABA) has been implicated as a key component in water-deficit-induced responses, including those triggered by drought, NaCl, and low- temperature stress. In this study a role for ABA in mediating the NaCl-stress-induced increases in tonoplast H+-translocating ATPase (V-ATPase) and Na+/H+ antiport activity in Mesembryanthemum crystallinum, leading to vacuolar Na+ sequestration, were investigated. NaCl or ABA treatment of adult M. crystallinum plants induced V-ATPase H+ transport activity, and when applied in combination, an additive effect on V-ATPase stimulation was observed. In contrast, treatment of juvenile plants with ABA did not induce V-ATPase activity, whereas NaCl treatment resulted in a similar response to that observed in adult plants. Na+/H+ antiport activity was induced in both juvenile and adult plants by NaCl, but ABA had no effect at either developmental stage. Results indicate that ABA-induced changes in V-ATPase activity are dependent on the plant reaching its adult phase, whereas NaCl-induced increases in V-ATPase and Na+/H+ antiport activity are independent of plant age. This suggests that ABA-induced V-ATPase activity may be linked to the stress-induced, developmentally programmed switch from C3 metabolism to Crassulacean acid metabolism in adult plants, whereas, vacuolar Na+ sequestration, mediated by the V-ATPase and Na+/H+ antiport, is regulated through ABA-independent pathways. PMID:10398716

  10. Exogenous abscisic acid significantly affects proteome in tea plant (Camellia sinensis) exposed to drought stress

    PubMed Central

    Zhou, Lin; Xu, Hui; Mischke, Sue; Meinhardt, Lyndel W; Zhang, Dapeng; Zhu, Xujun; Li, Xinghui; Fang, Wanping

    2014-01-01

    Tea [Camellia sinensis (L.) O. Kuntze] is an important economic crop, and drought is the most important abiotic stress affecting yield and quality. Abscisic acid (ABA) is an important phytohormone responsible for activating drought resistance. Increased understanding of ABA effects on tea plant under drought stress is essential to develop drought-tolerant tea genotypes, along with crop management practices that can mitigate drought stress. The objective of the present investigation is evaluation of effects of exogenous ABA on the leaf proteome in tea plant exposed to drought stress. Leaf protein patterns of tea plants under simulated drought stress [(polyethylene glycol (PEG)-treated] and exogenous ABA treatment were analyzed in a time-course experiment using two-dimensional electrophoresis (2-DE), followed by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry (MS). Among the 72 protein spots identified by MALDI-TOF MS, 16 proteins were downregulated and two were upregulated by exogenous ABA. The upregulated proteins have roles in glycolysis and photosystem II stabilization. Twenty-one protein spots were responsive to drought stress and most participate in carbohydrate and nitrogen metabolism, control of reactive oxygen species (ROS), defense, signaling or nucleic acid metabolism. The combined treatments of exogenous ABA and drought showed upregulation of 10 protein spots at 12 h and upregulation of 11 proteins at 72 h after initiation of drought stress. The results support the importance of the role that ABA plays in the tea plant during drought stress, by improving protein transport, carbon metabolism and expression of resistance proteins. PMID:27076915

  11. UDP-Glucosyltransferase71C5, a Major Glucosyltransferase, Mediates Abscisic Acid Homeostasis in Arabidopsis1[OPEN

    PubMed Central

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

    2015-01-01

    Abscisic acid (ABA) plays a key role in plant growth and development. The effect of ABA in plants mainly depends on its concentration, which is determined by a balance between biosynthesis and catabolism of ABA. In this study, we characterize a unique UDP-glucosyltransferase (UGT), UGT71C5, which plays an important role in ABA homeostasis by glucosylating ABA to abscisic acid-glucose ester (GE) in Arabidopsis (Arabidopsis thaliana). Biochemical analyses show that UGT71C5 glucosylates ABA in vitro and in vivo. Mutation of UGT71C5 and down-expression of UGT71C5 in Arabidopsis cause delay in seed germination and enhanced drought tolerance. In contrast, overexpression of UGT71C5 accelerates seed germination and reduces drought tolerance. Determination of the content of ABA and ABA-GE in Arabidopsis revealed that mutation in UGT71C5 and down-expression of UGT71C5 resulted in increased level of ABA and reduced level of ABA-GE, whereas overexpression of UGT71C5 resulted in reduced level of ABA and increased level of ABA-GE. Furthermore, altered levels of ABA in plants lead to changes in transcript abundance of ABA-responsive genes, correlating with the concentration of ABA regulated by UGT71C5 in Arabidopsis. Our work shows that UGT71C5 plays a major role in ABA glucosylation for ABA homeostasis. PMID:25713337

  12. Photoprotectant improves photostability and bioactivity of abscisic acid under UV radiation.

    PubMed

    Gao, Fei; Hu, Tanglu; Tan, Weiming; Yu, Chunxin; Li, Zhaohu; Zhang, Lizhen; Duan, Liusheng

    2016-05-01

    Photosensitivity causes serious drawback for abscisic acid (ABA) application, but preferable methods to stabilize the compound were not found yet. To select an efficient photoprotectant for the improvement of photostability and bioactivity of ABA when exposed to UV light, we tested the effects of a photostabilizer bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate (HS-770) and two UV absorbers 2-hydroxy-4-n-octoxy-benzophenone (UV-531) and 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid (BP-4) with or without HS-770 on the photodegradation of ABA. Water soluble UV absorber BP-4 and oil soluble UV absorber UV-531 showed significant photo-stabilizing capability on ABA, possibly due to competitive energy absorption of UVB by the UV absorbers. The two absorbers showed no significant difference. Photostabilizer HS-770 accelerated the photodegradation of ABA and did not improve the photo-stabilizing capability of BP-4, likely due to no absorption in UVB region and salt formation with ABA and BP-4. Approximately 26% more ABA was kept when 280mg/l ABA aqueous solution was irradiated by UV light for 2h in the presence of 200mg/l BP-4. What's more, its left bioactivity on wheat seed (JIMAI 22) germination was greatly kept by BP-4, comparing to that of ABA alone. The 300 times diluent of 280mg/l ABA plus 200mg/l BP-4 after 2h irradiation showed more than 13% inhibition on shoot and root growth of wheat seed than that of ABA diluent alone. We concluded that water soluble UV absorber BP-4 was an efficient agent to keep ABA activity under UV radiation. The results could be used to produce photostable products of ABA compound or other water soluble agrichemicals which are sensitive to UV radiation. The frequencies and amounts of the agrichemicals application could be thereafter reduced. PMID:26963431

  13. Abscisic acid influx into human nucleated cells occurs through the anion exchanger AE2.

    PubMed

    Vigliarolo, Tiziana; Zocchi, Elena; Fresia, Chiara; Booz, Valeria; Guida, Lucrezia

    2016-06-01

    Abscisic acid (ABA) is a hormone conserved from cyanobacteria to higher plants, where it regulates responses to environmental stimuli. ABA also plays a role in mammalian physiology, pointedly in inflammatory responses and in glycemic control. As the animal ABA receptor is on the intracellular side of the plasma membrane, a transporter is required for the hormone's action. Here we demonstrate that ABA transport in human nucleated cells occurs via the anion exchanger AE2. Together with the recent demonstration that ABA influx into human erythrocytes occurs via Band 3, this result identifies the AE family members as the mammalian ABA transporters. PMID:27015766

  14. Abscisic acid and other plant hormones: Methods to visualize distribution and signaling.

    PubMed

    Waadt, Rainer; Hsu, Po-Kai; Schroeder, Julian I

    2015-12-01

    The exploration of plant behavior on a cellular scale in a minimal invasive manner is key to understanding plant adaptations to their environment. Plant hormones regulate multiple aspects of growth and development and mediate environmental responses to ensure a successful life cycle. To monitor the dynamics of plant hormone actions in intact tissue, we need qualitative and quantitative tools with high temporal and spatial resolution. Here, we describe a set of biological instruments (reporters) for the analysis of the distribution and signaling of various plant hormones. Furthermore, we provide examples of their utility for gaining novel insights into plant hormone action with a deeper focus on the drought hormone abscisic acid. PMID:26577078

  15. Abscisic acid and other plant hormones: Methods to visualize distribution and signaling

    PubMed Central

    Waadt, Rainer; Hsu, Po-Kai; Schroeder, Julian I.

    2015-01-01

    The exploration of plant behavior on a cellular scale in a minimal invasive manner is key to understanding plant adaptations to their environment. Plant hormones regulate multiple aspects of growth and development and mediate environmental responses to ensure a successful life cycle. To monitor the dynamics of plant hormone actions in intact tissue, we need qualitative and quantitative tools with high temporal and spatial resolution. Here, we describe a set of biological instruments (reporters) for the analysis of the distribution and signaling of various plant hormones. Furthermore, we provide examples of their utility for gaining novel insights into plant hormone action with a deeper focus on the drought hormone abscisic acid. PMID:26577078

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

    PubMed

    Sorrentino, Giuseppe; Haworth, Matthew; Wahbi, Said; Mahmood, Tariq; Zuomin, Shi; Centritto, Mauro

    2016-01-01

    The rate of photosynthesis (A) of plants exposed to water deficit is a function of stomatal (gs) and mesophyll (gm) conductance determining the availability of CO2 at the site of carboxylation within the chloroplast. Mesophyll conductance often represents the greatest impediment to photosynthetic uptake of CO2, and a crucial determinant of the photosynthetic effects of drought. Abscisic acid (ABA) plays a fundamental role in signalling and co-ordination of plant responses to drought; however, the effect of ABA on gm is not well-defined. Rose, cherry, olive and poplar were exposed to exogenous ABA and their leaf gas exchange parameters recorded over a four hour period. Application with ABA induced reductions in values of A, gs and gm in all four species. Reduced gm occurred within one hour of ABA treatment in three of the four analysed species; indicating that the effect of ABA on gm occurs on a shorter timescale than previously considered. These declines in gm values associated with ABA were not the result of physical changes in leaf properties due to altered turgor affecting movement of CO2, or caused by a reduction in the sub-stomatal concentration of CO2 (Ci). Increased [ABA] likely induces biochemical changes in the properties of the interface between the sub-stomatal air-space and mesophyll layer through the actions of cooporins to regulate the transport of CO2. The results of this study provide further evidence that gm is highly responsive to fluctuations in the external environment, and stress signals such as ABA induce co-ordinated modifications of both gs and gm in the regulation of photosynthesis. PMID:26862904

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

    PubMed Central

    Sorrentino, Giuseppe; Haworth, Matthew; Wahbi, Said; Mahmood, Tariq; Zuomin, Shi; Centritto, Mauro

    2016-01-01

    The rate of photosynthesis (A) of plants exposed to water deficit is a function of stomatal (gs) and mesophyll (gm) conductance determining the availability of CO2 at the site of carboxylation within the chloroplast. Mesophyll conductance often represents the greatest impediment to photosynthetic uptake of CO2, and a crucial determinant of the photosynthetic effects of drought. Abscisic acid (ABA) plays a fundamental role in signalling and co-ordination of plant responses to drought; however, the effect of ABA on gm is not well-defined. Rose, cherry, olive and poplar were exposed to exogenous ABA and their leaf gas exchange parameters recorded over a four hour period. Application with ABA induced reductions in values of A, gs and gm in all four species. Reduced gm occurred within one hour of ABA treatment in three of the four analysed species; indicating that the effect of ABA on gm occurs on a shorter timescale than previously considered. These declines in gm values associated with ABA were not the result of physical changes in leaf properties due to altered turgor affecting movement of CO2, or caused by a reduction in the sub-stomatal concentration of CO2 (Ci). Increased [ABA] likely induces biochemical changes in the properties of the interface between the sub-stomatal air-space and mesophyll layer through the actions of cooporins to regulate the transport of CO2. The results of this study provide further evidence that gm is highly responsive to fluctuations in the external environment, and stress signals such as ABA induce co-ordinated modifications of both gs and gm in the regulation of photosynthesis. PMID:26862904

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

    PubMed Central

    2014-01-01

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

  19. C2-Domain Abscisic Acid-Related Proteins Mediate the Interaction of PYR/PYL/RCAR Abscisic Acid Receptors with the Plasma Membrane and Regulate Abscisic Acid Sensitivity in Arabidopsis[C][W

    PubMed Central

    Rodriguez, Lesia; Diaz, Maira; Rodrigues, Americo; Izquierdo-Garcia, Ana C.; Peirats-Llobet, Marta; Fernandez, Maria A.; Antoni, Regina; Fernandez, Daniel; Marquez, Jose A.; Mulet, Jose M.; Albert, Armando; Rodriguez, Pedro L.

    2014-01-01

    Membrane-delimited abscisic acid (ABA) signal transduction plays a critical role in early ABA signaling, but the molecular mechanisms linking core signaling components to the plasma membrane are unclear. We show that transient calcium-dependent interactions of PYR/PYL ABA receptors with membranes are mediated through a 10-member family of C2-domain ABA-related (CAR) proteins in Arabidopsis thaliana. Specifically, we found that PYL4 interacted in an ABA-independent manner with CAR1 in both the plasma membrane and nucleus of plant cells. CAR1 belongs to a plant-specific gene family encoding CAR1 to CAR10 proteins, and bimolecular fluorescence complementation and coimmunoprecipitation assays showed that PYL4-CAR1 as well as other PYR/PYL-CAR pairs interacted in plant cells. The crystal structure of CAR4 was solved, which revealed that, in addition to a classical calcium-dependent lipid binding C2 domain, a specific CAR signature is likely responsible for the interaction with PYR/PYL receptors and their recruitment to phospholipid vesicles. This interaction is relevant for PYR/PYL function and ABA signaling, since different car triple mutants affected in CAR1, CAR4, CAR5, and CAR9 genes showed reduced sensitivity to ABA in seedling establishment and root growth assays. In summary, we identified PYR/PYL-interacting partners that mediate a transient Ca2+-dependent interaction with phospholipid vesicles, which affects PYR/PYL subcellular localization and positively regulates ABA signaling. PMID:25465408

  20. C2-domain abscisic acid-related proteins mediate the interaction of PYR/PYL/RCAR abscisic acid receptors with the plasma membrane and regulate abscisic acid sensitivity in Arabidopsis.

    PubMed

    Rodriguez, Lesia; Gonzalez-Guzman, Miguel; Diaz, Maira; Rodrigues, Americo; Izquierdo-Garcia, Ana C; Peirats-Llobet, Marta; Fernandez, Maria A; Antoni, Regina; Fernandez, Daniel; Marquez, Jose A; Mulet, Jose M; Albert, Armando; Rodriguez, Pedro L

    2014-12-01

    Membrane-delimited abscisic acid (ABA) signal transduction plays a critical role in early ABA signaling, but the molecular mechanisms linking core signaling components to the plasma membrane are unclear. We show that transient calcium-dependent interactions of PYR/PYL ABA receptors with membranes are mediated through a 10-member family of C2-domain ABA-related (CAR) proteins in Arabidopsis thaliana. Specifically, we found that PYL4 interacted in an ABA-independent manner with CAR1 in both the plasma membrane and nucleus of plant cells. CAR1 belongs to a plant-specific gene family encoding CAR1 to CAR10 proteins, and bimolecular fluorescence complementation and coimmunoprecipitation assays showed that PYL4-CAR1 as well as other PYR/PYL-CAR pairs interacted in plant cells. The crystal structure of CAR4 was solved, which revealed that, in addition to a classical calcium-dependent lipid binding C2 domain, a specific CAR signature is likely responsible for the interaction with PYR/PYL receptors and their recruitment to phospholipid vesicles. This interaction is relevant for PYR/PYL function and ABA signaling, since different car triple mutants affected in CAR1, CAR4, CAR5, and CAR9 genes showed reduced sensitivity to ABA in seedling establishment and root growth assays. In summary, we identified PYR/PYL-interacting partners that mediate a transient Ca(2+)-dependent interaction with phospholipid vesicles, which affects PYR/PYL subcellular localization and positively regulates ABA signaling. PMID:25465408

  1. Increasing abscisic acid levels by immunomodulation in barley grains induces precocious maturation without changing grain composition

    PubMed Central

    Staroske, Nicole; Conrad, Udo; Kumlehn, Jochen; Hensel, Götz; Radchuk, Ruslana; Erban, Alexander; Kopka, Joachim; Weschke, Winfriede; Weber, Hans

    2016-01-01

    Abscisic acid (ABA) accumulates in seeds during the transition to the seed filling phase. ABA triggers seed maturation, storage activity, and stress signalling and tolerance. Immunomodulation was used to alter the ABA status in barley grains, with the resulting transgenic caryopses responding to the anti-ABA antibody gene expression with increased accumulation of ABA. Calculation of free versus antibody-bound ABA reveals large excess of free ABA, increasing signficantly in caryopses from 10 days after fertilization. Metabolite and transcript profiling in anti-ABA grains expose triggered and enhanced ABA-functions such as transcriptional up-regulation of sucrose-to-starch metabolism, storage protein synthesis and ABA-related signal transduction. Thus, enhanced ABA during transition phases induces precocious maturation but negatively interferes with growth and development. Anti-ABA grains display broad constitutive gene induction related to biotic and abiotic stresses. Most of these genes are ABA- and/or stress-inducible, including alcohol and aldehyde dehydrogenases, peroxidases, chaperones, glutathione-S-transferase, drought- and salt-inducible proteins. Conclusively, ABA immunomodulation results in precocious ABA accumulation that generates an integrated response of stress and maturation. Repression of ABA signalling, occurring in anti-ABA grains, potentially antagonizes effects caused by overshooting production. Finally, mature grain weight and composition are unchanged in anti-ABA plants, although germination is somewhat delayed. This indicates that anti-ABA caryopses induce specific mechanisms to desensitize ABA signalling efficiently, which finally yields mature grains with nearly unchanged dry weight and composition. Such compensation implicates the enormous physiological and metabolic flexibilities of barley grains to adjust effects of unnaturally high ABA amounts in order to ensure and maintain proper grain development. PMID:26951372

  2. Increasing abscisic acid levels by immunomodulation in barley grains induces precocious maturation without changing grain composition.

    PubMed

    Staroske, Nicole; Conrad, Udo; Kumlehn, Jochen; Hensel, Götz; Radchuk, Ruslana; Erban, Alexander; Kopka, Joachim; Weschke, Winfriede; Weber, Hans

    2016-04-01

    Abscisic acid (ABA) accumulates in seeds during the transition to the seed filling phase. ABA triggers seed maturation, storage activity, and stress signalling and tolerance. Immunomodulation was used to alter the ABA status in barley grains, with the resulting transgenic caryopses responding to the anti-ABA antibody gene expression with increased accumulation of ABA. Calculation of free versus antibody-bound ABA reveals large excess of free ABA, increasing signficantly in caryopses from 10 days after fertilization. Metabolite and transcript profiling in anti-ABA grains expose triggered and enhanced ABA-functions such as transcriptional up-regulation of sucrose-to-starch metabolism, storage protein synthesis and ABA-related signal transduction. Thus, enhanced ABA during transition phases induces precocious maturation but negatively interferes with growth and development. Anti-ABA grains display broad constitutive gene induction related to biotic and abiotic stresses. Most of these genes are ABA- and/or stress-inducible, including alcohol and aldehyde dehydrogenases, peroxidases, chaperones, glutathione-S-transferase, drought- and salt-inducible proteins. Conclusively, ABA immunomodulation results in precocious ABA accumulation that generates an integrated response of stress and maturation. Repression of ABA signalling, occurring in anti-ABA grains, potentially antagonizes effects caused by overshooting production. Finally, mature grain weight and composition are unchanged in anti-ABA plants, although germination is somewhat delayed. This indicates that anti-ABA caryopses induce specific mechanisms to desensitize ABA signalling efficiently, which finally yields mature grains with nearly unchanged dry weight and composition. Such compensation implicates the enormous physiological and metabolic flexibilities of barley grains to adjust effects of unnaturally high ABA amounts in order to ensure and maintain proper grain development. PMID:26951372

  3. Water deficit-induced changes in abscisic acid, growth polysomes, and translatable RNA in soybean hypocotyls. [Glycine max L

    SciTech Connect

    Bensen, R.J.; Boyer, J.S.; Mullet, J.E. )

    1988-01-01

    Soybean seedlings (Glycine max L.) were germinated and dark-grown in water-saturated vermiculite for 48 hours, then transferred either to water-saturated vermiculite or to low water potential vermiculite. A decrease in growth rate was detectable within 0.8 hour post-transfer to low water potential vermiculite. A fourfold increase in the abscisic acid content of the elongating region was observed within 0.5 hour. At 24 hours post-transfer, hypocotyl elongation was severely arrested and abscisic acid reached its highest measured level. A comparison of the polyA{sup +} RNA populations isolated at 24 hours post-transfer from the elongating region of water-saturated and low water potential vermiculite-grown seedlings was made by two-dimensional polyacrylamide gel analysis of in vitro translation products. It revealed both increases and decreases in the relative amounts of a number of translation products. Rewatering seedlings grown in low water potential vermiculite at 24 hours post-transfer led to a total recovery in growth rate within 0.5 hour, while abscisic acid in the elongating hypocotyl region required 1 to 2 hours to return to uninduced levels. Application of 1.0 millimolar {+-} abscisic acid to well-watered seedlings resulted in a 48% reduction in hypocotyl growth rate during the first 2 hours after treatment. Plants treated with abscisic acid for 24 hours had a lower polysome content than control plants. However, hypocotyl growth inhibition in abscisic acid-treated seedlings preceded the decline in polysome content.

  4. Pseudomonas syringae pv. tomato hijacks the Arabidopsis abscisic acid signalling pathway to cause disease

    PubMed Central

    de Torres-Zabala, Marta; Truman, William; Bennett, Mark H; Lafforgue, Guillaume; Mansfield, John W; Rodriguez Egea, Pedro; Bögre, Laszlo; Grant, Murray

    2007-01-01

    We have found that a major target for effectors secreted by Pseudomonas syringae is the abscisic acid (ABA) signalling pathway. Microarray data identified a prominent group of effector-induced genes that were associated with ABA biosynthesis and also responses to this plant hormone. Genes upregulated by effector delivery share a 42% overlap with ABA-responsive genes and are also components of networks induced by osmotic stress and drought. Strongly induced were NCED3, encoding a key enzyme of ABA biosynthesis, and the abscisic acid insensitive 1 (ABI1) clade of genes encoding protein phosphatases type 2C (PP2Cs) involved in the regulation of ABA signalling. Modification of PP2C expression resulting in ABA insensitivity or hypersensitivity led to restriction or enhanced multiplication of bacteria, respectively. Levels of ABA increased rapidly during bacterial colonisation. Exogenous ABA application enhanced susceptibility, whereas colonisation was reduced in an ABA biosynthetic mutant. Expression of the bacterial effector AvrPtoB in planta modified host ABA signalling. Our data suggest that a major virulence strategy is effector-mediated manipulation of plant hormone homeostasis, which leads to the suppression of defence responses. PMID:17304219

  5. Cytosolic Alkalinization Mediated by Abscisic Acid Is Necessary, but Not Sufficient, for Abscisic Acid-Induced Gene Expression in Barley Aleurone Protoplasts 1

    PubMed Central

    van der Veen, Renske; Heimovaara-Dijkstra, Sjoukje; Wang, Mei

    1992-01-01

    We investigated whether intracellular pH (pHi) is a causal mediator in abscisic acid (ABA)-induced gene expression. We measured the change in pHi by a “null-point” method during stimulation of barley (Hordeum vulgare cv Himalaya) aleurone protoplasts with ABA and found that ABA induces an increase in pHi from 7.11 to 7.30 within 45 min after stimulation. This increase is inhibited by plasma membrane H+-ATPase inhibitors, which induce a decrease in pHi, both in the presence and absence of ABA. This ABA-induced pHi increase precedes the expression of RAB-16 mRNA, as measured by northern analysis. ABA-induced pHi changes can be bypassed or clamped by addition of either the weak acids 5,5-dimethyl-2,4-oxazolidinedione and propionic acid, which decrease the pHi, or the weak bases methylamine and ammonia, which increase the pHi. Artificial pHi increases or decreases induced by weak bases or weak acids, respectively, do not induce RAB-16 mRNA expression. Clamping of the pHi at a high value with methylamine or ammonia treatment affected the ABA-induced increase of RAB-16 mRNA only slightly. However, inhibition of the ABA-induced pHi increase with weak acid or proton pump inhibitor treatments strongly inhibited the ABA-induced RAB-16 mRNA expression. We conclude that, although the ABA-induced the pHi increase is correlated with and even precedes the induction of RAB-16 mRNA expression and is an essential component of the transduction pathway leading from the hormone to gene expression, it is not sufficient to cause such expression. Images Figure 5 Figure 6 PMID:16653048

  6. The disturbance of small RNA pathways enhanced abscisic acid response and multiple stress responses in Arabidopsis.

    PubMed

    Zhang, Jian-Feng; Yuan, Li-Jie; Shao, Yi; Du, Wei; Yan, Da-Wei; Lu, Ying-Tang

    2008-04-01

    The phytohormone abscisic acid (ABA) regulates plant growth and development as well as stress tolerance. To gain more insights into ABA signalling, a population of chemical-inducible activation-tagged Arabidopsis mutants was screened on the basis of the ABA effect on the inhibition of seed germination. Two novel ABA supersensitive mutants ABA supersensitive during germination1 (absg1) and absg2 were characterized as alleles of Dicer-like1 (DCL1) and HEN1, respectively, as microRNA biogenesis genes, and accordingly, these two mutants were renamed dcl1-11 and hen1-16. The dcl1-11 mutant was an ABA hypersensitive mutant for seed germination and root growth. Reverse transcriptase polymerase chain reaction assays revealed that the expression of ABA- and stress-responsive genes was increased in dcl1-11, as compared with the wild type (WT). Furthermore, the germination assay showed that dcl1-11 was also more sensitive to salt and osmotic stress. The hen1-16 mutant also showed supersensitive to ABA during seed germination. Further analysis showed that, among the microRNA biogenesis genes, all the other mutants were not only enhanced in sensitivity to ABA, salt and osmotic stress, but also enhanced the expression of ABA-responsive genes. In addition to the mutants in the microRNA biogenesis, the interruption of the production of crucial components of other small RNA pathways such as dcl2, dcl3 and dcl4 also caused ABA supersensitive during germination. PMID:18208512

  7. In planta changes in protein phosphorylation induced by the plant hormone abscisic acid

    PubMed Central

    Kline, Kelli G.; Barrett-Wilt, Gregory A.; Sussman, Michael R.

    2010-01-01

    Abscisic acid (ABA) is a hormone that controls seed dormancy and germination as well as the overall plant response to important environmental stresses such as drought. Recent studies have demonstrated that the ABA-bound receptor binds to and inhibits a class of protein phosphatases. To identify more broadly the phosphoproteins affected by this hormone in vivo, we used 14N/15N metabolic labeling to perform a quantitative untargeted mass spectrometric analysis of the Arabidopsis thaliana phosphoproteome following ABA treatment. We found that 50 different phosphopeptides had their phosphorylation state significantly altered by ABA over a treatment period lasting 5–30 min. Among these changes were increases in phosphorylation of subfamily 2 SNF1-related kinases and ABA-responsive basic leucine zipper transcription factors implicated in ABA signaling by previous in vitro studies. Furthermore, four members of the aquaporin family showed decreased phosphorylation at a carboxy-terminal serine which is predicted to cause closure of the water-transporting aquaporin gate, consistent with ABA's role in ameliorating the effect of drought. Finally, more than 20 proteins not previously known to be involved with ABA were found to have significantly altered phosphorylation levels. Many of these changes are phosphorylation decreases, indicating that an expanded model of ABA signaling, beyond simple phosphatase inhibition, may be necessary. This quantitative proteomics dataset provides a more comprehensive, albeit incomplete, view both of the protein targets whose biochemical activities are likely to be controlled by ABA and of the nature of the emerging phosphorylation and dephosphorylation cascades triggered by this hormone. PMID:20733066

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

    PubMed

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

    2012-04-01

    Reactive oxygen species (ROS) act as signal molecules for a variety of processes in plants. However, many questions about the roles of ROS in plants remain to be clarified. Here, we report the role of ROS in gibberellin (GA) and abscisic acid (ABA) signaling in barley (Hordeum vulgare) aleurone cells. The production of hydrogen peroxide (H2O2), a type of ROS, was induced by GA in aleurone cells but suppressed by ABA. Furthermore, exogenous H2O2 appeared to promote the induction of α-amylases by GA. In contrast, antioxidants suppressed the induction of α-amylases. Therefore, H2O2 seems to function in GA and ABA signaling, and in regulation of α-amylase production, in aleurone cells. To identify the target of H2O2 in GA and ABA signaling, we analyzed the interrelationships between H2O2 and DELLA proteins Slender1 (SLN1), GA-regulated Myb transcription factor (GAmyb), and ABA-responsive protein kinase (PKABA) and their roles in GA and ABA signaling in aleurone cells. In the presence of GA, exogenous H2O2 had little effect on the degradation of SLN1, the primary transcriptional repressor mediating GA signaling, but it promoted the production of the mRNA encoding GAMyb, which acts downstream of SLN1 and involves induction of α-amylase mRNA. Additionally, H2O2 suppressed the production of PKABA mRNA, which is induced by ABA:PKABA represses the production of GAMyb mRNA. From these observations, we concluded that H2O2 released the repression of GAMyb mRNA by PKABA and consequently promoted the production of α-amylase mRNA, thus suggesting that the H2O2 generated by GA in aleurone cells is a signal molecule that antagonizes ABA signaling. PMID:22291200

  9. Abscisic acid metabolism in relation to water stress and leaf age in Xanthium strumarium

    SciTech Connect

    Cornish, K.; Zeevaart, J.A.D.

    1984-12-01

    Intact plants of Xanthium strumarium L. were subjected to a water stress-recovery cycle. As the stress took effect, leaf growth ceased and stomatal resistance increased. The mature leaves then wilted, followed by the half expanded ones. Water, solute, and pressure potentials fell steadily in all leaves during the rest of the stress period. After 3 days, the young leaves lost turgor and the plants were rewatered. All the leaves rapidly regained turgor and the younger ones recommenced elongation. Stomatal resistance declined, but several days elapsed before pre-stress values were attained. Abscisic aid (ABA) and phaseic acid (PA) levels rose in all the leaves after the mature ones wilted. ABA-glucose ester (ABA-GE) levels increased to a lesser extent, and the young leaves contained little of this conjugate. PA leveled off in the older leaves during the last 24 hours of stress, and ABA levels declined slightly. The young leaves accumulated ABA and PA throughout the stress period and during the 14-hour period immediately following rewatering. The ABA and PA contents, expressed per unit dry weight, were highest in the young leaves. Upon rewatering, large quantities of PA appeared in the mature leaves as ABA levels fell to the pre-stress level within 14 hours. In the half expanded and young leaves, it took several days to reach pre-stress ABA values. ABA-GE synthesis ceased in the mature leaves, once the stress was relieved, but continued in the half expanded and young leaves for 2 days. Mature leaves, when detached and stressed, accumulated an amount of ABA similar to that in leaves on the intact plant. In contrast, detached and stressed young leaves produced little ABA. Studies with radioactive (+/-)-ABA indicated that in young leaves the conversion of ABA to PA took place at a much lower rate than in mature ones. 25 references, 10 figures, 2 tables.

  10. Large-scale proteome analysis of abscisic acid and ABSCISIC ACID INSENSITIVE3-dependent proteins related to desiccation tolerance in Physcomitrella patens.

    PubMed

    Yotsui, Izumi; Serada, Satoshi; Naka, Tetsuji; Saruhashi, Masashi; Taji, Teruaki; Hayashi, Takahisa; Quatrano, Ralph S; Sakata, Yoichi

    2016-03-18

    Desiccation tolerance is an ancestral feature of land plants and is still retained in non-vascular plants such as bryophytes and some vascular plants. However, except for seeds and spores, this trait is absent in vegetative tissues of vascular plants. Although many studies have focused on understanding the molecular basis underlying desiccation tolerance using transcriptome and proteome approaches, the critical molecular differences between desiccation tolerant plants and non-desiccation plants are still not clear. The moss Physcomitrella patens cannot survive rapid desiccation under laboratory conditions, but if cells of the protonemata are treated by the phytohormone abscisic acid (ABA) prior to desiccation, it can survive 24 h exposure to desiccation and regrow after rehydration. The desiccation tolerance induced by ABA (AiDT) is specific to this hormone, but also depends on a plant transcription factor ABSCISIC ACID INSENSITIVE3 (ABI3). Here we report the comparative proteomic analysis of AiDT between wild type and ABI3 deleted mutant (Δabi3) of P. patens using iTRAQ (Isobaric Tags for Relative and Absolute Quantification). From a total of 1980 unique proteins that we identified, only 16 proteins are significantly altered in Δabi3 compared to wild type after desiccation following ABA treatment. Among this group, three of the four proteins that were severely affected in Δabi3 tissue were Arabidopsis orthologous genes, which were expressed in maturing seeds under the regulation of ABI3. These included a Group 1 late embryogenesis abundant (LEA) protein, a short-chain dehydrogenase, and a desiccation-related protein. Our results suggest that at least three of these proteins expressed in desiccation tolerant cells of both Arabidopsis and the moss are very likely to play important roles in acquisition of desiccation tolerance in land plants. Furthermore, our results suggest that the regulatory machinery of ABA- and ABI3-mediated gene expression for desiccation

  11. The antagonistic regulation of abscisic acid-inhibited root growth by brassinosteroids is partially mediated via direct suppression of ABSCISIC ACID INSENSITIVE 5 expression by BRASSINAZOLE RESISTANT 1.

    PubMed

    Yang, Xiaorui; Bai, Yang; Shang, Jianxiu; Xin, Ruijiao; Tang, Wenqiang

    2016-09-01

    Brassinosteroids (BRs) and abscisic acid (ABA) are plant hormones that antagonistically regulate many aspects of plant growth and development; however, the mechanisms that regulate the crosstalk of these two hormones are still not well understood. BRs regulate plant growth and development by activating BRASSINAZOLE RESISTANT 1 (BZR1) family transcription factors. Here we show that the crosstalk between BRs and ABA signalling is partially mediated by BZR1 regulated gene expression. bzr1-1D is a dominant mutant with enhanced BR signalling; our results showed that bzr1-1D mutant is less sensitive to ABA-inhibited primary root growth. By RNA sequencing, a subset of BZR1 regulated ABA-responsive root genes were identified. Of these genes, the expression of a major ABA signalling component ABA INSENSITIVE 5 (ABI5) was found to be suppressed by BR and by BZR1. Additional evidences showed that BZR1 could bind strongly with several G-box cis-elements in the promoter of ABI5, suppress the expression of ABI5 and make plants less sensitive to ABA. Our study demonstrated that ABI5 is a direct target gene of BZR1, and modulating the expression of ABI5 by BZR1 plays important roles in regulating the crosstalk between the BR and ABA signalling pathways. PMID:27149247

  12. Functional annotation of the transcriptome of Sorghum bicolor in response to osmotic stress and abscisic acid

    PubMed Central

    2011-01-01

    Background Higher plants exhibit remarkable phenotypic plasticity allowing them to adapt to an extensive range of environmental conditions. Sorghum is a cereal crop that exhibits exceptional tolerance to adverse conditions, in particular, water-limiting environments. This study utilized next generation sequencing (NGS) technology to examine the transcriptome of sorghum plants challenged with osmotic stress and exogenous abscisic acid (ABA) in order to elucidate genes and gene networks that contribute to sorghum's tolerance to water-limiting environments with a long-term aim of developing strategies to improve plant productivity under drought. Results RNA-Seq results revealed transcriptional activity of 28,335 unique genes from sorghum root and shoot tissues subjected to polyethylene glycol (PEG)-induced osmotic stress or exogenous ABA. Differential gene expression analyses in response to osmotic stress and ABA revealed a strong interplay among various metabolic pathways including abscisic acid and 13-lipoxygenase, salicylic acid, jasmonic acid, and plant defense pathways. Transcription factor analysis indicated that groups of genes may be co-regulated by similar regulatory sequences to which the expressed transcription factors bind. We successfully exploited the data presented here in conjunction with published transcriptome analyses for rice, maize, and Arabidopsis to discover more than 50 differentially expressed, drought-responsive gene orthologs for which no function had been previously ascribed. Conclusions The present study provides an initial assemblage of sorghum genes and gene networks regulated by osmotic stress and hormonal treatment. We are providing an RNA-Seq data set and an initial collection of transcription factors, which offer a preliminary look into the cascade of global gene expression patterns that arise in a drought tolerant crop subjected to abiotic stress. These resources will allow scientists to query gene expression and functional

  13. Genetic Association Mapping Identifies Single Nucleotide Polymorphisms in Genes that Affect Abscisic Acid Levels in Maize Floral Tissues During Drought

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In maize, development of the female inflorescence and its floral parts is vulnerable to water stress at flowering, which causes loss of kernel set and productivity. While changes in the levels of sugars and abscisic acid (ABA) are thought to play a role in this stress response, the mechanistic basi...

  14. Multiple interactions of NaHER1 protein with abscisic acid signaling in Nicotiana attenuata plants

    PubMed Central

    Dinh, Son Truong; Baldwin, Ian T; Gális, Ivan

    2013-01-01

    Previously, we identified a novel herbivore elicitor-regulated protein in Nicotiana attenuata (NaHER1) that is required to suppress abscisic acid (ABA) catabolism during herbivore attack and activate a full defense response against herbivores. ABA, in addition to its newly defined role in defense activation, mainly controls seed germination and stomatal function of land plants. Here we show that N. attenuata seeds silenced in the expression of NaHER1 by RNA interference (irHER1) accumulated less ABA during germination, and germinated faster on ABA-containing media compared to WT. Curiously, epidermal cells of irHER1 plants were wrinkled, possibly due to the previously demonstrated increase in transpiration of irHER1 plants that may affect turgor and cause wrinkling of the cells. We conclude that NaHER1 is a highly pleiotropic regulator of ABA responses in N. attenuata plants. PMID:24022276

  15. Biological and Chemical Properties of the Epidioxide Isomer of Abscisic Acid and its Rearrangement Products

    PubMed Central

    Sondheimer, Ernest; Michniewicz, Barbara M.; Powell, Loyd E.

    1969-01-01

    The growth inhibitory activity of the epidioxide (II), a precursor in the synthesis of abscisic acid (ABA), has been confirmed with additional assay systems. Under physiological conditions the epidioxide is rearranged to give ABA and an isomer of ABA which has probably the structure V. This major product has very low, if any, biological activity. The biological activity of the epidioxide is explained by its partial conversion (about 20%) to ABA. The reaction rate was enhanced by heavy metal ions and decreased by EDTA. At pH 12.5, the decomposition of the epidioxide is slower than it is near neutrality and ABA is the predominant product. In the biological systems studied the activity of the epidioxide can be accounted for by nonenzymatic conversion to ABA. PMID:16657047

  16. Emerging roles of protein kinase CK2 in abscisic acid signaling

    PubMed Central

    Vilela, Belmiro; Pagès, Montserrat; Riera, Marta

    2015-01-01

    The phytohormone abscisic acid (ABA) regulates many aspects of plant growth and development as well as responses to multiple stresses. Post-translational modifications such as phosphorylation or ubiquitination have pivotal roles in the regulation of ABA signaling. In addition to the positive regulator sucrose non-fermenting-1 related protein kinase 2 (SnRK2), the relevance of the role of other protein kinases, such as CK2, has been recently highlighted. We have recently established that CK2 phosphorylates the maize ortholog of open stomata 1 OST1, ZmOST1, suggesting a role of CK2 phosphorylation in the control of ZmOST1 protein degradation (Vilela et al., 2015). CK2 is a pleiotropic enzyme involved in multiple developmental and stress-responsive pathways. This review summarizes recent advances that taken together suggest a prominent role of protein kinase CK2 in ABA signaling and related processes. PMID:26579189

  17. Abscisic Acid Elicits the Water-Stress Response in Root Hairs of Arabidopsis thaliana1

    PubMed Central

    Schnall, Jennifer A.; Quatrano, Ralph S.

    1992-01-01

    Water stress has been shown to cause root hairs to become short and bulbous. Because abscisic acid (ABA) mediates a variety of water-stress responses, we investigated the response of Arabidopsis thaliana root hairs to ABA. When wild-type root hairs were treated with ABA, they exhibited the water-stress response. The Arabidopsis mutants abi1 and abi2, which are insensitive to ABA at the seedling stage, did not display the root hair response. These data suggest that ABA may mediate the response of root hairs to water stress. The drought response of root hairs resulting in an inhibition of tip growth will provide an easy screen to select mutations that are insensitive to ABA and/or involved in tip growth. Images Figure 1 PMID:16652949

  18. A new look at stress: abscisic acid patterns and dynamics at high-resolution.

    PubMed

    Jones, Alexander M

    2016-04-01

    Abscisic acid (ABA) is a key phytohormone promoting abiotic stress tolerance as well as developmental processes such as seed dormancy. A spatiotemporal map of ABA concentrations would greatly advance our understanding of the cell type and timing of ABA action. Organ and tissue-level ABA measurements, as well as indirect in vivo measurements such as cell-specific transcriptional analysis of ABA metabolic enzymes and ABA-responsive promoters, have all contributed to current views of the localization and timing of ABA accumulations. Recently developed Förster resonance energy transfer (FRET) biosensors for ABA that sense ABA levels directly promise to add unprecedented resolution to in vivo ABA spatiotemporal mapping and expand our knowledge of the mechanisms controlling ABA levels in space and time. PMID:26201893

  19. G-protein coupling and nuclear translocation of the human abscisic acid receptor LANCL2

    PubMed Central

    Fresia, Chiara; Vigliarolo, Tiziana; Guida, Lucrezia; Booz, Valeria; Bruzzone, Santina; Sturla, Laura; Di Bona, Melody; Pesce, Mattia; Usai, Cesare; De Flora, Antonio; Zocchi, Elena

    2016-01-01

    Abscisic acid (ABA), a long known phytohormone, has been recently demonstrated to be present also in humans, where it targets cells of the innate immune response, mesenchymal and hemopoietic stem cells and cells involved in the regulation of systemic glucose homeostasis. LANCL2, a peripheral membrane protein, is the mammalian ABA receptor. We show that N-terminal glycine myristoylation causes LANCL2 localization to the plasmamembrane and to cytoplasmic membrane vesicles, where it interacts with the α subunit of a Gi protein and starts the ABA signaling pathway via activation of adenylate cyclase. Demyristoylation of LANCL2 by chemical or genetic means triggers its nuclear translocation. Nuclear enrichment of native LANCL2 is also induced by ABA treatment. Therefore human LANCL2 is a non-transmembrane G protein-coupled receptor susceptible to hormone-induced nuclear translocation. PMID:27222287

  20. G-protein coupling and nuclear translocation of the human abscisic acid receptor LANCL2.

    PubMed

    Fresia, Chiara; Vigliarolo, Tiziana; Guida, Lucrezia; Booz, Valeria; Bruzzone, Santina; Sturla, Laura; Di Bona, Melody; Pesce, Mattia; Usai, Cesare; De Flora, Antonio; Zocchi, Elena

    2016-01-01

    Abscisic acid (ABA), a long known phytohormone, has been recently demonstrated to be present also in humans, where it targets cells of the innate immune response, mesenchymal and hemopoietic stem cells and cells involved in the regulation of systemic glucose homeostasis. LANCL2, a peripheral membrane protein, is the mammalian ABA receptor. We show that N-terminal glycine myristoylation causes LANCL2 localization to the plasmamembrane and to cytoplasmic membrane vesicles, where it interacts with the α subunit of a Gi protein and starts the ABA signaling pathway via activation of adenylate cyclase. Demyristoylation of LANCL2 by chemical or genetic means triggers its nuclear translocation. Nuclear enrichment of native LANCL2 is also induced by ABA treatment. Therefore human LANCL2 is a non-transmembrane G protein-coupled receptor susceptible to hormone-induced nuclear translocation. PMID:27222287

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

    PubMed

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

    2009-01-23

    The plant hormone abscisic acid (ABA) plays a role in root gravitropism and has led to an intense debate over whether ABA acts similar to auxin by translating the gravitational signal into directional root growth. While tremendous advances have been made in the past two decades in establishing the role of auxin in root gravitropism, little progress has been made in characterizing the role of ABA in this response. In fact, roots of plants that have undetectable levels of ABA and that display a normal gravitropic response have raised some serious doubts about whether ABA plays any role in root gravitropism. Here, we show strong evidence that ABA plays a role opposite to that of auxin and that it is a negative regulator of the gravitropic response of Arabidopsis roots. PMID:19056344

  2. Negative regulation of abscisic acid signaling by the Brassica oleracea ABI1 ortholog.

    PubMed

    Yuan, Feifei; Wang, Mengyao; Hao, Hongmei; Zhang, Yanfeng; Zhao, Huixian; Guo, Aiguang; Xu, Hong; Zhou, Xiaona; Xie, Chang Gen

    2013-12-13

    ABI1 (ABA Insensitive 1) is an important component of the core regulatory network in early ABA (Abscisic acid) signaling. Here, we investigated the functions of an ABI1 ortholog in Brassica oleracea (BolABI1). The expression of BolABI1 was dramatically induced by drought, and constitutive expression of BolABI1 confers ABA insensitivity upon the wild-type. Subcellular localization and phosphatase assays reveal that BolABI1 is predominantly localized in the nucleus and harbors phosphatase activity. Furthermore, BolABI1 interacts with a homolog of OST1 (OPEN STOMATA 1) in B. oleracea (BolOST1) and can dephosphorylate ABI5 (ABA Insensitive 5) in vitro. Overall, these results suggest that BolABI1 is a functional PP2C-type protein phosphatase that is involved in the negative modulation of the ABA signaling pathway. PMID:24269821

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

    PubMed Central

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

    2016-01-01

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

  4. OsNAP connects abscisic acid and leaf senescence by fine-tuning abscisic acid biosynthesis and directly targeting senescence-associated genes in rice

    PubMed Central

    Liang, Chengzhen; Wang, Yiqin; Zhu, Yana; Tang, Jiuyou; Hu, Bin; Liu, Linchuan; Ou, Shujun; Wu, Hongkai; Sun, Xiaohong; Chu, Jinfang; Chu, Chengcai

    2014-01-01

    It has long been established that premature leaf senescence negatively impacts the yield stability of rice, but the underlying molecular mechanism driving this relationship remains largely unknown. Here, we identified a dominant premature leaf senescence mutant, prematurely senile 1 (ps1-D). PS1 encodes a plant-specific NAC (no apical meristem, Arabidopsis ATAF1/2, and cup-shaped cotyledon2) transcriptional activator, Oryza sativa NAC-like, activated by apetala3/pistillata (OsNAP). Overexpression of OsNAP significantly promoted senescence, whereas knockdown of OsNAP produced a marked delay of senescence, confirming the role of this gene in the development of rice senescence. OsNAP expression was tightly linked with the onset of leaf senescence in an age-dependent manner. Similarly, ChIP-PCR and yeast one-hybrid assays demonstrated that OsNAP positively regulates leaf senescence by directly targeting genes related to chlorophyll degradation and nutrient transport and other genes associated with senescence, suggesting that OsNAP is an ideal marker of senescence onset in rice. Further analysis determined that OsNAP is induced specifically by abscisic acid (ABA), whereas its expression is repressed in both aba1 and aba2, two ABA biosynthetic mutants. Moreover, ABA content is reduced significantly in ps1-D mutants, indicating a feedback repression of OsNAP on ABA biosynthesis. Our data suggest that OsNAP serves as an important link between ABA and leaf senescence. Additionally, reduced OsNAP expression leads to delayed leaf senescence and an extended grain-filling period, resulting in a 6.3% and 10.3% increase in the grain yield of two independent representative RNAi lines, respectively. Thus, fine-tuning OsNAP expression should be a useful strategy for improving rice yield in the future. PMID:24951508

  5. Abscisic Acid Flux Alterations Result in Differential Abscisic Acid Signaling Responses and Impact Assimilation Efficiency in Barley under Terminal Drought Stress1[C][W][OPEN

    PubMed Central

    Seiler, Christiane; Harshavardhan, Vokkaliga T.; Reddy, Palakolanu S.; Hensel, Götz; Kumlehn, Jochen; Eschen-Lippold, Lennart; Rajesh, Kalladan; Korzun, Viktor; Wobus, Ulrich; Lee, Justin; Selvaraj, Gopalan; Sreenivasulu, Nese

    2014-01-01

    Abscisic acid (ABA) is a central player in plant responses to drought stress. How variable levels of ABA under short-term versus long-term drought stress impact assimilation and growth in crops is unclear. We addressed this through comparative analysis, using two elite breeding lines of barley (Hordeum vulgare) that show senescence or stay-green phenotype under terminal drought stress and by making use of transgenic barley lines that express Arabidopsis (Arabidopsis thaliana) 9-cis-epoxycarotenoid dioxygenase (AtNCED6) coding sequence or an RNA interference (RNAi) sequence of ABA 8′-hydroxylase under the control of a drought-inducible barley promoter. The high levels of ABA and its catabolites in the senescing breeding line under long-term stress were detrimental for assimilate productivity, whereas these levels were not perturbed in the stay-green type that performed better. In transgenic barley, drought-inducible AtNCED expression afforded temporal control in ABA levels such that the ABA levels rose sooner than in wild-type plants but also subsided, unlike as in the wild type , to near-basal levels upon prolonged stress treatment due to down-regulation of endogenous HvNCED genes. Suppressing of ABA catabolism with the RNA interference approach of ABA 8′-hydroxylase caused ABA flux during the entire period of stress. These transgenic plants performed better than the wild type under stress to maintain a favorable instantaneous water use efficiency and better assimilation. Gene expression analysis, protein structural modeling, and protein-protein interaction analyses of the members of the PYRABACTIN RESISTANCE1/PYRABACTIN RESISTANCE1-LIKE/REGULATORY COMPONENT OF ABA RECEPTORS, TYPE 2C PROTEIN PHOSPHATASE Sucrose non-fermenting1-related protein kinase2, and ABA-INSENSITIVE5/ABA-responsive element binding factor family identified specific members that could potentially impact ABA metabolism and stress adaptation in barley. PMID:24610749

  6. Molecular Mechanisms in the Activation of Abscisic Acid Receptor PYR1

    PubMed Central

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

    2013-01-01

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

  7. Low irradiances affect abscisic acid, indole-3-acidic acid, and cytokinin levels of wheat (Triticum aestivum L.) tissues

    NASA Technical Reports Server (NTRS)

    Nan, R.; Carman, J. G.; Salisbury, F. B.

    1999-01-01

    Wheat (Triticum aestivum L.) plants were grown under four irradiance levels: 1,400, 400, 200, and 100 micromol m-2 s-1. Leaves and roots were sampled before, during, and after the boot stage, and levels of abscisic acid (ABA), indole-3-acetic acid (IAA), zeatin, zeatin riboside, dihydrozeatin, dihydrozeatin riboside, isopentenyl adenine, and isopentenyl adenosine were quantified using noncompetitive indirect ELISA systems. Levels of IAA in leaves and roots of plants exposed to 100 micromol m-2 s-1 of irradiance were 0.7 and 2.9 micromol kg-1 dry mass (DM), respectively. These levels were 0.2 and 1.0 micromol kg-1 DM, respectively, when plants were exposed to 1,400 micromol m-2 s-1. Levels of ABA in leaves and roots of plants exposed to 100 micromol m-2 s-1 were 0.65 and 0.55 micromol kg-1 DM, respectively. They were 0.24 micromol kg-1 DM (both leaves and roots) when plants were exposed to 1,400 micromol m-2 s-1. Levels of isopentenyl adenosine in leaves (24.3 nmol kg-1 DM) and roots (29.9 nmol kg-1 DM) were not affected by differences in the irradiance regime. Similar values were obtained in a second experiment. Other cytokinins could not be detected (<10 nmol kg 1 DM) in either experiment with the sample sizes used (150-600 mg DM for roots and shoots, respectively).

  8. An Abscisic Acid-Independent Oxylipin Pathway Controls Stomatal Closure and Immune Defense in Arabidopsis

    PubMed Central

    Mondy, Samuel; Tranchimand, Sylvain; Rumeau, Dominique; Boudsocq, Marie; Garcia, Ana Victoria; Douki, Thierry; Bigeard, Jean; Laurière, Christiane; Chevalier, Anne; Castresana, Carmen; Hirt, Heribert

    2013-01-01

    Plant stomata function in innate immunity against bacterial invasion and abscisic acid (ABA) has been suggested to regulate this process. Using genetic, biochemical, and pharmacological approaches, we demonstrate that (i) the Arabidopsis thaliana nine-specific-lipoxygenase encoding gene, LOX1, which is expressed in guard cells, is required to trigger stomatal closure in response to both bacteria and the pathogen-associated molecular pattern flagellin peptide flg22; (ii) LOX1 participates in stomatal defense; (iii) polyunsaturated fatty acids, the LOX substrates, trigger stomatal closure; (iv) the LOX products, fatty acid hydroperoxides, or reactive electrophile oxylipins induce stomatal closure; and (v) the flg22-mediated stomatal closure is conveyed by both LOX1 and the mitogen-activated protein kinases MPK3 and MPK6 and involves salicylic acid whereas the ABA-induced process depends on the protein kinases OST1, MPK9, or MPK12. Finally, we show that the oxylipin and the ABA pathways converge at the level of the anion channel SLAC1 to regulate stomatal closure. Collectively, our results demonstrate that early biotic signaling in guard cells is an ABA-independent process revealing a novel function of LOX1-dependent stomatal pathway in plant immunity. PMID:23526882

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

    PubMed

    Sulochana, Sujitha Balakrishnan; Arumugam, Muthu

    2016-08-01

    Scenedesmus quadricauda, accumulated more lipid but with a drastic reduction in biomass yield during nitrogen starvation. Abscisic acid (ABA) being a stress responsible hormone, its effect on growth and biomass with sustainable lipid yield during nitrogen depletion was studied. The result revealed that the ABA level shoots up at 24h (27.21pmol/L) during the onset of nitrogen starvation followed by a sharp decline. The external supplemented ABA showed a positive effect on growth pattern (38×10(6)cells/ml) at a lower concentration. The dry biomass yield is also increasing up to 2.1 fold compared to nitrogen deficient S. quadricauda. The lipid content sustains in 1 and 2μM concentration of ABA under nitrogen-deficient condition. The fatty acid composition of ABA treated S. quadricauda cultures with respect to nitrogen-starved cells showed 11.17% increment in saturated fatty acid content, the desired lipid composition for biofuel application. PMID:26949054

  10. Metabolism of Abscisic Acid in Guard Cells of Vicia faba L. and Commelina communis L. 1

    PubMed Central

    Grantz, David A.; Ho, Tuan-Hua David; Uknes, Scott J.; Cheeseman, John M.; Boyer, John S.

    1985-01-01

    Metabolism of abscisic acid (ABA) was investigated in isolated guard cells and in mesophyll tissue of Vicia faba L. and Commelina communis L. After incubation in buffer containing [G-3H]±ABA, the tissue was extracted by grinding and the metabolites separated by thin layer chromatography. Guard cells of Commelina metabolized ABA to phaseic acid (PA), dihydrophaseic acid (DPA), and alkali labile conjugates. Guard cells of Vicia formed only the conjugates. Mesophyll cells of Commelina accumulated DPA while mesophyll cells of Vicia accumulated PA. Controls showed that the observed metabolism was not due to extracellular enzyme contaminants nor to bacterial action. Metabolism of ABA in guard cells suggests a mechanism for removal of ABA, which causes stomatal closure of both species, from the stomatal complex. Conversion to metabolites which are inactive in stomatal regulation, within the cells controlling stomatal opening, might precede detectable changes in levels of ABA in bulk leaf tissue. The differences observed between Commelina and Vicia in metabolism of ABA in guard cells, and in the accumulation product in the mesophyll, may be related to differences in stomatal sensitivity to PA which have been reported for these species. Images Fig. 1 PMID:16664207

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

    PubMed

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

    2015-09-01

    The hormonal mechanisms involved in palm seed germination are not fully understood. To better understand how germination is regulated in Arecaceae, we used macaw palm (Acrocomia aculeata (Jacq.) Lodd. Ex Mart.) seed as a model. Endogenous hormone concentrations, tocopherol and tocotrienol and lipid peroxidation during germination were studied separately in the embryo and endosperm. Evaluations were performed in dry (D), imbibed (I), germinated (G) and non-germinated (NG) seeds treated (+GA3 ) or not treated (control) with gibberellins (GA). With GA3 treatment, seeds germinated faster and to a higher percentage than control seeds. The +GA3 treatment increased total bioactive GA in the embryo during germination relative to the control. Abscisic acid (ABA) concentrations decreased gradually from D to G in both tissues. Embryos of G seeds had a lower ABA content than NG seeds in both treatments. The GA/ABA ratio in the embryo was significantly higher in G than NG seeds. The +GA3 treatment did not significantly affect the GA/ABA ratio in either treatment. Cytokinin content increased from dry to germinated seeds. Jasmonic acid (JA) increased and 1-aminocyclopropane-1-carboylic acid (ACC) decreased after imbibition. In addition, α-tocopherol and α-tocotrienol decreased, while lipid peroxidation increased in the embryo during germination. We conclude that germination in macaw palm seed involves reductions in ABA content and, consequently, increased GA/ABA in the embryo. Furthermore, the imbibition process generates oxidative stress (as observed by changes in vitamin E and MDA). PMID:25818098

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

    PubMed

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

    2015-01-01

    The effect of abscisic acid (ABA) and fluridone on the content of endogenous phytohormones and free polyamines and the intensity of oxidative stress was studied in plants of Mesembryanthemum crystallinum L. under salinity. It was shown that the pretreatment of plant roots with 1 μM ABA, followed by the action of 300 mM NaCl, caused a protective effect and improved the physiological state of the plants, which was manifested in increased biomass and content of available cytokinins and reduced values of the indicators of oxidative stress. It was noted that the inhibitor fluridone reduced the effect of ABA and acted as a pro-oxidant. PMID:26021155

  13. General roles of abscisic and jasmonic acids in gene activation as a result of mechanical wounding.

    PubMed Central

    Hildmann, T; Ebneth, M; Peña-Cortés, H; Sánchez-Serrano, J J; Willmitzer, L; Prat, S

    1992-01-01

    Exogenous application of abscisic acid (ABA) has been shown to induce a systemic pattern of proteinase inhibitor II (pin2) mRNA accumulation identical to that induced by mechanical wounding. Evidence is presented that the ABA-specific response is not restricted to pin2 genes but appears to be part of a general reaction to wound stress. Four other wound-induced, ABA-responsive genes that encode two additional proteinase inhibitors, the proteolytic enzyme leucine aminopeptidase, and the biosynthetic enzyme threonine deaminase were isolated from potato plants. Wounding or treatment with ABA resulted in a pattern of accumulation of these mRNAs very similar to that of pin2. ABA-deficient plants did not accumulate any of the mRNAs upon wounding, although they showed normal levels of expression upon ABA treatment. Also, application of methyl jasmonate (MeJA) induced a strong accumulation of these transcripts, both in wild-type and in ABA-deficient plants, thus supporting a role for jasmonic acid as an intermediate in the signaling pathway that leads from ABA accumulation in response to wounding to the transcriptional activation of the genes. PMID:1392612

  14. Abscisic acid deficiency increases defence responses against Myzus persicae in Arabidopsis.

    PubMed

    Hillwig, Melissa S; Chiozza, Mariana; Casteel, Clare L; Lau, Siau Ting; Hohenstein, Jessica; Hernández, Enrique; Jander, Georg; MacIntosh, Gustavo C

    2016-02-01

    Comparison of Arabidopsis thaliana (Arabidopsis) gene expression induced by Myzus persicae (green peach aphid) feeding, aphid saliva infiltration and abscisic acid (ABA) treatment showed a significant positive correlation. In particular, ABA-regulated genes are over-represented among genes that are induced by M. persicae saliva infiltration into Arabidopsis leaves. This suggests that the induction of ABA-related gene expression could be an important component of the Arabidopsis-aphid interaction. Consistent with this hypothesis, M. persicae populations induced ABA production in wild-type plants. Furthermore, aphid populations were smaller on Arabidopsis aba1-1 mutants, which cannot synthesize ABA, and showed a significant preference for wild-type plants compared with the mutant. Total free amino acids, which play an important role in aphid nutrition, were not altered in the aba1-1 mutant line, but the levels of isoleucine (Ile) and tryptophan (Trp) were differentially affected by aphids in wild-type and mutant plants. Recently, indole glucosinolates have been shown to promote aphid resistance in Arabidopsis. In this study, 4-methoxyindol-3-ylmethylglucosinolate was more abundant in the aba1-1 mutant than in wild-type Arabidopsis, suggesting that the induction of ABA signals that decrease the accumulation of defence compounds may be beneficial for aphids. PMID:25943308

  15. Relative quantification of phosphoproteomic changes in grapevine (Vitis vinifera L.) leaves in response to abscisic acid.

    PubMed

    Rattanakan, Supakan; George, Iniga; Haynes, Paul A; Cramer, Grant R

    2016-01-01

    In a previous transcriptomic analysis, abscisic acid (ABA) was found to affect the abundance of a number of transcripts in leaves of Cabernet Sauvignon grapevines with roots that had been exposed to 10 μm ABA for 2 h. Other work has indicated that ABA affects protein abundance and protein phosphorylation as well. In this study we investigated changes in protein abundance and phosphorylation of Cabernet Sauvignon grapevine leaves. Protein abundance was assessed by both label-free and isobaric-label quantitive proteomic methods. Each identified common proteins, but also additional proteins not found with the other method. Overall, several thousand proteins were identified and several hundred were quantified. In addition, hundreds of phosphoproteins were identified. Tens of proteins were found to be affected in the leaf after the roots had been exposed to ABA for 2 h, more than half of them were phosphorylated proteins. Many phosphosites were confirmed and several new ones were identified. ABA increased the abundance of some proteins, but the majority of the proteins had their protein abundance decreased. Many of these proteins were involved in growth and plant organ development, including proteins involved in protein synthesis, photosynthesis, sugar and amino-acid metabolism. This study provides new insights into how ABA regulates plant responses and acclimation to water deficits. PMID:27366326

  16. Regulation of acyltransferase activity in immature maize embryos by abscisic acid and the osmotic environment.

    PubMed Central

    Pacheco-Moisés, F; Valencia-Turcotte, L; Altuzar-Martínez, M; Rodríguez-Sotres, R

    1997-01-01

    Maize (Zes mays L.) embryos, isolated from the developing seed and incubated in dilute buffer, show reduced triacylglycerol (TAG) synthesis, and accumulation stops after 24 h. Synthesis and accumulation can be maintained at high levels if the incubation medium contains abscisic acid (ABA) and/or a high osmotic concentration. Radiolabeled free fatty acids accumulate at higher levels in embryos that contain less TAG, and acetyl coenzyme A carboxylase activity remains essentially unchanged under all of the conditions tested. In contrast, the activities of the acyltransferases required for TAG synthesis remain high only in embryos incubated with ABA and/or a high osmotic concentration. Dose-response curves showed that 4 microM of ABA or mannitol at -1.0 MPa elicits a full response; both values are within the range considered to be physiological. The TAG synthesis capacity and discylglycerol acyltransferase activity lost by pretreatment of the embryos can be restored by re-exposure to ABA or high osmoticum. Germination is not involved because isolated scutellum halves showed the same changes in enzyme activity found in the whole embryo but did not germinate. Our results provide direct evidence for the regulation of TAG-synthesizing activities in maize embryos by ABA and the osmotic potential of the environment. PMID:9232885

  17. Relative quantification of phosphoproteomic changes in grapevine (Vitis vinifera L.) leaves in response to abscisic acid

    PubMed Central

    Rattanakan, Supakan; George, Iniga; Haynes, Paul A; Cramer, Grant R

    2016-01-01

    In a previous transcriptomic analysis, abscisic acid (ABA) was found to affect the abundance of a number of transcripts in leaves of Cabernet Sauvignon grapevines with roots that had been exposed to 10 μm ABA for 2 h. Other work has indicated that ABA affects protein abundance and protein phosphorylation as well. In this study we investigated changes in protein abundance and phosphorylation of Cabernet Sauvignon grapevine leaves. Protein abundance was assessed by both label-free and isobaric-label quantitive proteomic methods. Each identified common proteins, but also additional proteins not found with the other method. Overall, several thousand proteins were identified and several hundred were quantified. In addition, hundreds of phosphoproteins were identified. Tens of proteins were found to be affected in the leaf after the roots had been exposed to ABA for 2 h, more than half of them were phosphorylated proteins. Many phosphosites were confirmed and several new ones were identified. ABA increased the abundance of some proteins, but the majority of the proteins had their protein abundance decreased. Many of these proteins were involved in growth and plant organ development, including proteins involved in protein synthesis, photosynthesis, sugar and amino-acid metabolism. This study provides new insights into how ABA regulates plant responses and acclimation to water deficits. PMID:27366326

  18. 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. PMID:23037505

  19. Possible involvement of abscisic acid in the induction of secondary somatic embryogenesis on seed-coat-derived carrot somatic embryos.

    PubMed

    Ogata, Yumiko; Iizuka, Misato; Nakayama, Daisuke; Ikeda, Miho; Kamada, Hiroshi; Koshiba, Tomokazu

    2005-06-01

    When seed coats (pericarps) were picked from 14-day-old carrot (Daucus carota) seedlings and cultured on agar plates, embryogenic cell clusters were produced very rapidly at a high frequency on the open side edge. Embryo induction progressed without auxin treatment; indeed treatment caused the formation of non-embryogenic callus. The embryogenic tissues (primary embryos) developed normally until the torpedo stage; however, after this a number of secondary somatic embryos were produced in the hypocotyl and root regions. "Tertiary" embryos were formed on some of the secondary embryos, but many developed into normal plantlets. The primary embryos contained significantly higher levels of abscisic acid (ABA) than the hypocotyl-derived normal and seed-coat-derived secondary embryos. Fluridone inhibited the induction of secondary embryogenesis, while exogenously supplied ABA induced not only "tertiary" embryogenesis on the seed-coat-derived secondary embryos, but also secondary embryos on the hypocotyl-derived normal somatic embryos. These results indicate that ABA is one of the important endogenous factors for the induction of secondary embryogenesis on carrot somatic embryos. Higher levels of indole-3-acetic acid (IAA) in primary embryos also suggest the presence of some concerted effect of ABA and IAA on the induction of secondary embryogenesis in primary embryos. PMID:15770487

  20. Designed abscisic acid analogs as antagonists of PYL-PP2C receptor interactions.

    PubMed

    Takeuchi, Jun; Okamoto, Masanori; Akiyama, Tomonori; Muto, Takuya; Yajima, Shunsuke; Sue, Masayuki; Seo, Mitsunori; Kanno, Yuri; Kamo, Tsunashi; Endo, Akira; Nambara, Eiji; Hirai, Nobuhiro; Ohnishi, Toshiyuki; Cutler, Sean R; Todoroki, Yasushi

    2014-06-01

    The plant stress hormone abscisic acid (ABA) is critical for several abiotic stress responses. ABA signaling is normally repressed by group-A protein phosphatases 2C (PP2Cs), but stress-induced ABA binds Arabidopsis PYR/PYL/RCAR (PYL) receptors, which then bind and inhibit PP2Cs. X-ray structures of several receptor-ABA complexes revealed a tunnel above ABA's 3' ring CH that opens at the PP2C binding interface. Here, ABA analogs with sufficiently long 3' alkyl chains were predicted to traverse this tunnel and block PYL-PP2C interactions. To test this, a series of 3'-alkylsulfanyl ABAs were synthesized with different alkyl chain lengths. Physiological, biochemical and structural analyses revealed that a six-carbon alkyl substitution produced a potent ABA antagonist that was sufficiently active to block multiple stress-induced ABA responses in vivo. This study provides a new approach for the design of ABA analogs, and the results validated structure-based design for this target class. PMID:24792952

  1. Tetraploid Rangpur lime rootstock increases drought tolerance via enhanced constitutive root abscisic acid production.

    PubMed

    Allario, Thierry; Brumos, Javier; Colmenero-Flores, Jose M; Iglesias, Domingo J; Pina, Jose A; Navarro, Luis; Talon, Manuel; Ollitrault, Patrick; Morillon, Raphaël

    2013-04-01

    Whole-genome duplication, or polyploidy, is common in many plant species and often leads to better adaptation to adverse environmental condition. However, little is known about the physiological and molecular determinants underlying adaptation. We examined the drought tolerance in diploid (2x) and autotetraploid (4x) clones of Rangpur lime (Citrus limonia) rootstocks grafted with 2x Valencia Delta sweet orange (Citrus sinensis) scions, named V/2xRL and V/4xRL, respectively. Physiological experiments to study root-shoot communication associated with gene expression studies in roots and leaves were performed. V/4xRL was much more tolerant to water deficit than V/2xRL. Gene expression analysis in leaves and roots showed that more genes related to the response to water stress were differentially expressed in V/2xRL than in V/4xRL. Prior to the stress, when comparing V/4xRL to V/2xRL, V/4xRL leaves had lower stomatal conductance and greater abscisic acid (ABA) content. In roots, ABA content was higher in V/4xRL and was associated to a greater expression of drought responsive genes, including CsNCED1, a pivotal regulatory gene of ABA biosynthesis. We conclude that tetraploidy modifies the expression of genes in Rangpur lime citrus roots to regulate long-distance ABA signalling and adaptation to stress. PMID:23050986

  2. Activation of glucosidase via stress-induced polymerization rapidly increases active pools of abscisic acid.

    PubMed

    Lee, Kwang Hee; Piao, Hai Lan; Kim, Ho-Youn; Choi, Sang Mi; Jiang, Fan; Hartung, Wolfram; Hwang, Ildoo; Kwak, June M; Lee, In-Jung; Hwang, Inhwan

    2006-09-22

    Abscisic acid (ABA) is a phytohormone critical for plant growth, development, and adaptation to various stress conditions. Plants have to adjust ABA levels constantly to respond to changing physiological and environmental conditions. To date, the mechanisms for fine-tuning ABA levels remain elusive. Here we report that AtBG1, a beta-glucosidase, hydrolyzes glucose-conjugated, biologically inactive ABA to produce active ABA. Loss of AtBG1 causes defective stomatal movement, early germination, abiotic stress-sensitive phenotypes, and lower ABA levels, whereas plants with ectopic AtBG1 accumulate higher ABA levels and display enhanced tolerance to abiotic stress. Dehydration rapidly induces polymerization of AtBG1, resulting in a 4-fold increase in enzymatic activity. Furthermore, diurnal increases in ABA levels are attributable to polymerization-mediated AtBG1 activation. We propose that the activation of inactive ABA pools by polymerized AtBG1 is a mechanism by which plants rapidly adjust ABA levels and respond to changing environmental cues. PMID:16990135

  3. Agrochemical control of plant water use using engineered abscisic acid receptors.

    PubMed

    Park, Sang-Youl; Peterson, Francis C; Mosquna, Assaf; Yao, Jin; Volkman, Brian F; Cutler, Sean R

    2015-04-23

    Rising temperatures and lessening fresh water supplies are threatening agricultural productivity and have motivated efforts to improve plant water use and drought tolerance. During water deficit, plants produce elevated levels of abscisic acid (ABA), which improves water consumption and stress tolerance by controlling guard cell aperture and other protective responses. One attractive strategy for controlling water use is to develop compounds that activate ABA receptors, but agonists approved for use have yet to be developed. In principle, an engineered ABA receptor that can be activated by an existing agrochemical could achieve this goal. Here we describe a variant of the ABA receptor PYRABACTIN RESISTANCE 1 (PYR1) that possesses nanomolar sensitivity to the agrochemical mandipropamid and demonstrate its efficacy for controlling ABA responses and drought tolerance in transgenic plants. Furthermore, crystallographic studies provide a mechanistic basis for its activity and demonstrate the relative ease with which the PYR1 ligand-binding pocket can be altered to accommodate new ligands. Thus, we have successfully repurposed an agrochemical for a new application using receptor engineering. We anticipate that this strategy will be applied to other plant receptors and represents a new avenue for crop improvement. PMID:25652827

  4. Arabidopsis abscisic acid receptors play an important role in disease resistance.

    PubMed

    Lim, Chae Woo; Lee, Sung Chul

    2015-06-01

    Stomata are natural pores of plants and constitute the entry points for water during transpiration. However, they also facilitate the ingress of potentially harmful bacterial pathogens. The phytohormone abscisic acid (ABA) plays a pivotal role in protecting plants against biotic stress, by regulating stomatal closure. In the present study, we investigated the mechanism whereby ABA influences plant defense responses to Pseudomonas syringae pv. tomato (Pst) DC3000, which is a virulent bacterial pathogen of Arabidopsis, at the pre-invasive stage. We found that overexpression of two ABA receptors, namely, RCAR4/PYL10-OX and RCAR5/PYL11-OX (hereafter referred to as RCARs), resulted in ABA-hypersensitive phenotypes being exhibited during the seed germination and seedling growth stages. Sensitivity to ABA enhanced the resistance of RCAR4-OX and RCAR5-OX plants to Pst DC3000, through promoting stomatal closure leading to the development of resistance to this bacterial pathogen. Protein phosphatase HAB1 is an important component that is responsible for ABA signaling and which interacts with ABA receptors. We found that hab1 mutants exhibited enhanced resistance to Pst DC3000; moreover, similar to RCAR4-OX and RCAR5-OX plants, this enhanced resistance was correlated with stomatal closure. Taken together, our findings demonstrate that alteration of RCAR4- or RCAR5-HAB1 mediated ABA signaling influences resistance to bacterial pathogens via stomatal regulation. PMID:25969135

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

    PubMed Central

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

    2015-01-01

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

  6. A Nuclear Factor Regulates Abscisic Acid Responses in Arabidopsis1[W][OA

    PubMed Central

    Kim, Min Jung; Shin, Ryoung; Schachtman, Daniel P.

    2009-01-01

    Abscisic acid (ABA) is a plant hormone that regulates plant growth as well as stress responses. In this study, we identified and characterized a new Arabidopsis (Arabidopsis thaliana) protein, Nuclear Protein X1 (NPX1), which was up-regulated by stress and treatment with exogenous ABA. Stomatal closure, seed germination, and primary root growth are well-known ABA responses that were less sensitive to ABA in NPX1-overexpressing plants. NPX1-overexpressing plants were more drought sensitive, and the changes in response to drought were due to the altered guard cell sensitivity to ABA in transgenic plants and not to a lack of ABA production. The nuclear localization of NPX1 correlated with changes in the expression of genes involved in ABA biosynthesis and ABA signal transduction. To understand the function of NPX1, we searched for interacting proteins and found that an ABA-inducible NAC transcription factor, TIP, interacted with NPX1. Based on the whole plant phenotypes, we hypothesized that NPX1 acts as a transcriptional repressor, and this was demonstrated in yeast, where we showed that TIP was repressed by NPX1. Our results indicate that the previously unknown protein NPX1 acts as a negative regulator in plant response to changes in environmental conditions through the control of ABA-regulated gene expression. The characterization of this factor enhances our understanding of guard cell function and the mechanisms that plants use to modulate water loss from leaves under drought conditions. PMID:19759343

  7. Seed Dormancy and Responses of Caryopses, Embryos, and Calli to Abscisic Acid in Wheat 1

    PubMed Central

    Morris, C. F.; Moffatt, J. M.; Sears, R. G.; Paulsen, G. M.

    1989-01-01

    Preharvest sprouting of wheat (Triticum aestivum L.) is associated with inadequate seed dormancy. Although abscisic acid (ABA) has often been suggested to play a central role in developing seed, its involvement in dormancy of mature seed lacks firm experimental evidence and endogenous ABA levels are not well correlated with germinability. We examined genotypic and temporal variation in wheat seed and embryo germination responses to ABA and determined whether differential sensitivity of embryos to ABA extended to growth of embryo-derived calli. Germination of Parker 76 caryopses, which have little dormancy at maturity, was only slightly inhibited by ABA, whereas germination of Clark's Cream, a highly dormant genotype, was greatly inhibited. Responsiveness of caryopses to ABA and dormancy of seeds decreased concurrently during afterripening. Germination of embryos excised from dormant and nondormant seeds was more responsive to ABA but otherwise was similar to that of caryopses, indicating that differential response to ABA occurs in the embryo. Growth of calli derived from immature embryos of two sprouting-susceptible wheat genotypes exceeded growth of calli from Clark's Cream, but no distinct differences in response to ABA among the genotypes were apparent. We concluded that the action of ABA is similar in developing and mature seeds, that genotypic and temporal variation in embryo responsiveness to endogenous ABA may be involved in dormancy, and that ABA probably acts in concert with other endogenous constituents. PMID:16666821

  8. Putting the brakes on: abscisic acid as a central environmental regulator of stomatal development.

    PubMed

    Chater, Caspar C C; Oliver, James; Casson, Stuart; Gray, Julie E

    2014-04-01

    Stomata are produced by a controlled series of epidermal cell divisions. The molecular underpinnings of this process are becoming well understood, but mechanisms that determine plasticity of stomatal patterning to many exogenous and environmental cues remain less clear. Light quantity and quality, vapour pressure deficit, soil water content, and CO2 concentration are detected by the plant, and new leaves adapt their stomatal densities accordingly. Mature leaves detect these environmental signals and relay messages to immature leaves to tell them how to adapt and grow. Stomata on mature leaves may act as stress signal-sensing and transduction centres, locally by aperture adjustment, and at long distance by optimizing stomatal density to maximize future carbon gain while minimizing water loss. Although mechanisms of stomatal aperture responses are well characterized, the pathways by which mature stomata integrate environmental signals to control immature epidermal cell fate, and ultimately stomatal density, are not. Here we evaluate current understanding of the latter through the influence of the former. We argue that mature stomata, as key portals by which plants coordinate their carbon and water relations, are controlled by abscisic acid (ABA), both metabolically and hydraulically, and that ABA is also a core regulator of environmentally determined stomatal development. PMID:24611444

  9. A screen for genes that function in abscisic acid signaling in Arabidopsis thaliana.

    PubMed Central

    Nambara, Eiji; Suzuki, Masaharu; Abrams, Suzanne; McCarty, Donald R; Kamiya, Yuji; McCourt, Peter

    2002-01-01

    The plant hormone abscisic acid (ABA) controls many aspects of plant growth and development under a diverse range of environmental conditions. To identify genes functioning in ABA signaling, we have carried out a screen for mutants that takes advantage of the ability of wild-type Arabidopsis seeds to respond to (-)-(R)-ABA, an enantiomer of the natural (+)-(S)-ABA. The premise of the screen was to identify mutations that preferentially alter their germination response in the presence of one stereoisomer vs. the other. Twenty-six mutants were identified and genetic analysis on 23 lines defines two new loci, designated CHOTTO1 and CHOTTO2, and a collection of new mutant alleles of the ABA-insensitive genes, ABI3, ABI4, and ABI5. The abi5 alleles are less sensitive to (+)-ABA than to (-)-ABA. In contrast, the abi3 alleles exhibit a variety of differences in response to the ABA isomers. Genetic and molecular analysis of these alleles suggests that the ABI3 transcription factor may perceive multiple ABA signals. PMID:12136027

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

    PubMed

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

    2015-01-01

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

  11. Thiol-based Redox Proteins in Brassica napus Guard Cell Abscisic Acid and Methyl Jasmonate Signaling

    PubMed Central

    Zhu, Mengmeng; Zhu, Ning; Song, Wen-yuan; Harmon, Alice C.; Assmann, Sarah M.; Chen, Sixue

    2014-01-01

    SUMMARY Reversibly oxidized cysteine sulfhydryl groups serve as redox sensors or targets of redox sensing that are important in different physiological processes. Little is known, however, about redox sensitive proteins in guard cells and how they function in stomatal signaling. In this study, Brassica napus guard cell proteins altered by redox in response to abscisic acid (ABA) or methyl jasmonate (MeJA) were identified by complementary proteomics approaches, saturation differential in-gel electrophoresis (DIGE) and isotope-coded affinity tag (ICAT). In total, 65 and 118 potential redox responsive proteins were identified in ABA and MeJA treated guard cells, respectively. All the proteins contain at least one cysteine, and over half of them are predicted to form intra-molecular disulfide bonds. Most of the proteins fall into the functional groups of energy, stress and defense, and metabolism. Based on the peptide sequences identified by mass spectrometry, 30 proteins were common to ABA and MeJA treated samples. A total of 44 cysteines was mapped in all the identified proteins, and their levels of redox sensitivity were quantified. Two of the proteins, a SNRK2 kinase and an isopropylmalate dehydrogenase were confirmed to be redox regulated and involved in stomatal movement. This study creates an inventory of potential redox switches, and highlights a protein redox regulatory mechanism in guard cell ABA and MeJA signal transduction. PMID:24580573

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

    PubMed

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

    2012-03-01

    Inhalation of quartz induces silicosis, a lung disease where alveolar macrophages release inflammatory mediators, including prostaglandin-E(2) (PGE(2)) and tumor necrosis factor α (TNF-α). Here we report the pivotal role of abscisic acid (ABA), a recently discovered human inflammatory hormone, in silica-induced activation of murine RAW264.7 macrophages and of rat alveolar macrophages (AMs). Stimulation of both RAW264.7 cells and AMs with quartz induced a significant increase of ABA release (5- and 10-fold, respectively), compared to untreated cells. In RAW264.7 cells, autocrine ABA released after quartz stimulation sequentially activates the plasma membrane receptor LANCL2 and NADPH oxidase, generating a Ca(2+) influx resulting in NFκ B nuclear translocation and PGE(2) and TNF-α release (3-, 2-, and 3.5-fold increase, respectively, compared to control, unstimulated cells). Quartz-stimulated RAW264.7 cells silenced for LANCL2 or preincubated with a monoclonal antibody against ABA show an almost complete inhibition of NFκ B nuclear translocation and PGE(2) and TNF-α release compared to controls electroporated with a scramble oligonucleotide or preincubated with an unrelated antibody. AMs showed similar early and late ABA-induced responses as RAW264.7 cells. These findings identify ABA and LANCL2 as key mediators in quartz-induced inflammation, providing possible new targets for antisilicotic therapy. PMID:22042223

  13. Abscisic acid, xanthoxin and violaxanthin in the caps of gravistimulated maize roots

    NASA Technical Reports Server (NTRS)

    Feldman, L. J.; Arroyave, N. J.; Sun, P. S.

    1985-01-01

    The occurrence and distribution of abscisic acid (ABA), xanthoxin (Xa) and the carotenoid violaxanthin (Va) were investigated in root tips of maize (Zea mays L. cv. Merit). In roots grown in the dark, Va and ABA were present in relatively high amounts in the root cap and in low amounts in the adjacent terminal 1.5 mm of the root. Xanthoxin was present in equal concentrations in both regions. In roots exposed to light, the ABA distribution was reversed, with relatively low levels in the root cap and high levels in the adjacent 1.5-mm segment. Light also caused a decrease in Va in both regions of the root and an increase in Xa, especially in the cap. In the maize cultivar used for this work, light is necessary for gravitropic curving. This response occurs within the same time frame as the light-induced ABA redistribution as well as the changes in the levels of Va and Xa. These data are consistent with a role for ABA in root gravitropism and support the proposal that Xa may arise from the turnover of Va.

  14. Stress-induced accumulation of wheat germ agglutinin and abscisic acid in roots of wheat seedlings

    SciTech Connect

    Cammue, B.P.A.; Broekaert, W.F.; Kellens, J.T.C.; Peumans, W.J. ); Raikhel, N.V. )

    1989-12-01

    Wheat germ agglutinin (WGA) levels in roots of 2-day-old wheat seedlings increased up to three-fold when stressed by air-drying. Similar results were obtained when seedling roots were incubated either in 0.5 molar mannitol or 180 grams per liter polyethylene glycol 6,000, with a peak level of WGA after 5 hours of stress. Longer periods of osmotic treatment resulted in a gradual decline of WGA in the roots. Since excised wheat roots incorporate more ({sup 35}S)cysteine into WGA under stress conditions, the observed increase of lectin levels is due to de novo synthesis. Measurement of abscisic acid (ABA) levels in roots of control and stressed seedlings indicated a 10-fold increase upon air-drying. Similarly, a five- and seven-fold increase of ABA content of seedling roots was found after 2 hours of osmotic stress by polyethylene glycol 6,000 and mannitol, respectively. Finally, the stress-induced increase of WGA in wheat roots could be inhibited by growing seedlings in the presence of fluridone, an inhibitor of ABA synthesis. These results indicate that roots of water-stressed wheat seedlings (a) contain more WGA as a result of an increased de novo synthesis of this lectin, and (b) exhibit higher ABA levels. The stress-induced increase of lectin accumulation seems to be under control of ABA.

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

    SciTech Connect

    Melcher, Karsten; Ng, Ley-Moy; Zhou, X Edward; Soon, Fen-Fen; Xu, Yong; Suino-Powell, Kelly M; Park, Sang-Youl; Weiner, Joshua J; Fujii, Hiroaki; Chinnusamy, Viswanathan; Kovach, Amanda; Li, Jun; Wang, Yonghong; Li, Jiayang; Peterson, Francis C; Jensen, Davin R; Yong, Eu-Leong; Volkman, Brian F; Cutler, Sean R; Zhu, Jian-Kang; Xu, H Eric

    2010-01-12

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

  16. Quantitative Proteomics Reveals the Flooding-Tolerance Mechanism in Mutant and Abscisic Acid-Treated Soybean.

    PubMed

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

    2016-06-01

    Flooding negatively affects the growth of soybean, and several flooding-specific stress responses have been identified; however, the mechanisms underlying flooding tolerance in soybean remain unclear. To explore the initial flooding tolerance mechanisms in soybean, flooding-tolerant mutant and abscisic acid (ABA)-treated plants were analyzed. In the mutant and ABA-treated soybeans, 146 proteins were commonly changed at the initial flooding stress. Among the identified proteins, protein synthesis-related proteins, including nascent polypeptide-associated complex and chaperonin 20, and RNA regulation-related proteins were increased in abundance both at protein and mRNA expression. However, these proteins identified at the initial flooding stress were not significantly changed during survival stages under continuous flooding. Cluster analysis indicated that glycolysis- and cell wall-related proteins, such as enolase and polygalacturonase inhibiting protein, were increased in abundance during survival stages. Furthermore, lignification of root tissue was improved even under flooding stress. Taken together, these results suggest that protein synthesis- and RNA regulation-related proteins play a key role in triggering tolerance to the initial flooding stress in soybean. Furthermore, the integrity of cell wall and balance of glycolysis might be important factors for promoting tolerance of soybean root to flooding stress during survival stages. PMID:27132649

  17. Temperature Regulation of Growth and Endogenous Abscisic Acid-like Content of Tulipa gesneriana L

    PubMed Central

    Aung, Louis H.; De Hertogh, August A.

    1979-01-01

    The ontogenetic changes of dry matter and abscisic acid (ABA)-like content in the component organs of Tulipa gesneriana L. `Paul Richter' and `Golden Melody' under two temperature storage regimes were determined. The organ dry matter and ABA showed marked differences during 13 and 5 C dry storage and during subsequent growth at 13 C. Scale dry matter of both cultivars declined sharply when grown at 13 C. The basalplate of the cultivars showed an initial gain in dry matter, but declined subsequently. The shoot of both cultivars stored at 13 C exhibited greater dry matter gain than at 5 C. In contrast, the bulblets of the cultivars at 5 C showed a much higher rate of dry matter accumulation than at 13 C. An inhibitory substance extracted from tulip bulb organs co-chromatographed with authentic ABA and had identical thin layer chromatographic RF values of ABA in five solvent systems. The total ABA content per bulb increased 3-fold in `Golden Melody' and 2- to 4-fold in `Paul Richter' during the course of the temperature treatments. ABA was low in the scales and shoot, but it was high in the basalplate, bulblets, and roots. It is suggested that the probable ABA biosynthetic sites of tulip bulb are the developing bulblets, basalplate, and roots. PMID:16660867

  18. Ubiquitin-specific protease 24 negatively regulates abscisic acid signalling in Arabidopsis thaliana.

    PubMed

    Zhao, Jinfeng; Zhou, Huapeng; Zhang, Ming; Gao, Yanan; Li, Long; Gao, Ying; Li, Ming; Yang, Yuhong; Guo, Yan; Li, Xueyong

    2016-02-01

    Abscisic acid (ABA) is an important plant hormone integrating environmental stress and plant growth. Protein ubiquitination and deubiquitination are reversible processes catalysed by E3 ubiquitin ligase and deubiquitinating enzyme, respectively. Lots of E3 ubiquitin ligase and transcriptional factors modified by ubiquitination were reported to modulate ABA signalling. However, no deubiquitinating enzyme has been identified that functions in ABA signalling until now. Here, we isolated an ABA overly sensitive mutant, ubp24, in which the gene encoding ubiquitin-specific protease 24 (UBP24, At4g30890) was disrupted by a T-DNA insertion. The ubp24 mutant was hypersensitive to ABA and salt stress in both post-germinative growth and seedling growth. However, stomata closure in the ubp24 mutant was less sensitive to ABA, and the ubp24 mutant showed drought sensitivity. UBP24 possessed deubiquitinating enzyme activity, and the activity was essential for UBP24 function. Additionally, UBP24 formed homodimer in vivo. UBP24 was genetically upstream of ABI2, and the phosphatase activity of protein phosphatase 2C was decreased in the ubp24 mutant compared with the wild type in the presence of ABA. These results uncover an important regulatory role for the ubiquitin-specific protease in response to ABA and salt stress in plant. PMID:26290265

  19. Open Stomata 1 (OST1) is limiting in abscisic acid responses of Arabidopsis guard cells.

    PubMed

    Acharya, Biswa R; Jeon, Byeong Wook; Zhang, Wei; Assmann, Sarah M

    2013-12-01

    Open Stomata 1 (OST1) (SnRK2.6 or SRK2E), a serine/threonine protein kinase, is a positive regulator in abscisic acid (ABA)-mediated stomatal response, but OST1-regulation of K(+) and Ca(2+) currents has not been studied directly in guard cells and it is unknown whether OST1 activity is limiting in ABA-mediated stomatal responses. We employed loss-of-function and gain-of-function approaches to study native ABA responses of Arabidopsis guard cells. We performed stomatal aperture bioassays, patch clamp analyses and reactive oxygen species (ROS) measurements. ABA inhibition of inward K(+) channels and light-induced stomatal opening are reduced in ost1 mutants while transgenic plants overexpressing OST1 show ABA hypersensitivity in these responses. ost1 mutants are insensitive to ABA-induced stomatal closure, regulation of slow anion currents, Ca(2+) -permeable channel activation and ROS production while OST1 overexpressing lines are hypersensitive for these responses, resulting in accelerated stomatal closure in response to ABA. Overexpression of OST1 in planta in the absence of ABA application does not affect basal apertures or ion currents. Moreover, we demonstrate the physical interaction of OST1 with the inward K(+) channel KAT1, the anion channel SLAC1, and the NADPH oxidases AtrbohD and AtrbohF. Our findings support OST1 as a critical limiting component in ABA regulation of stomatal apertures, ion channels and NADPH oxidases in Arabidopsis guard cells. PMID:24033256

  20. The Arabidopsis LYST INTERACTING PROTEIN 5 Acts in Regulating Abscisic Acid Signaling and Drought Response

    PubMed Central

    Xia, Zongliang; Huo, Yongjin; Wei, Yangyang; Chen, Qiansi; Xu, Ziwei; Zhang, Wei

    2016-01-01

    Multivesicular bodies (MVBs) are unique endosomes containing vesicles in the lumens and play essential roles in many eukaryotic cellular processes. The Arabidopsis LYST INTERACTING PROTEIN 5 (LIP5), a positive regulator of MVB biogenesis, has critical roles in biotic and abiotic stress responses. However, whether the abscisic acid (ABA) signaling is involved in LIP5-mediated stress response is largely unknown. Here, we report that LIP5 functions in regulating ABA signaling and drought response in Arabidopsis. Analyses of a LIP5 promoter-β-glucuronidase (GUS) construct revealed substantial GUS activity in whole seedlings. The expression of LIP5 was induced by ABA and drought, and overexpression of LIP5 led to ABA hypersensitivity, enhanced stomatal closure, reduced water loss, and, therefore, increased drought tolerance. On the contrary, LIP5 knockdown mutants showed ABA-insensitive phenotypes and reduced drought tolerance; suggesting that LIP5 acts in regulating ABA response. Further analysis using a fluorescent dye revealed that ABA and water stress induced cell endocytosis or vesicle trafficking in a largely LIP5-dependent manner. Furthermore, expression of several drought- or ABA-inducible marker genes was significantly down-regulated in the lip5 mutant seedlings. Collectively, our data suggest that LIP5 positively regulates drought tolerance through ABA-mediated cell signaling. PMID:27313589

  1. Acetylated 1,3-diaminopropane antagonizes abscisic acid-mediated stomatal closing in Arabidopsis.

    PubMed

    Jammes, Fabien; Leonhardt, Nathalie; Tran, Daniel; Bousserouel, Hadjira; Véry, Anne-Aliénor; Renou, Jean-Pierre; Vavasseur, Alain; Kwak, June M; Sentenac, Hervé; Bouteau, François; Leung, Jeffrey

    2014-07-01

    Faced with declining soil-water potential, plants synthesize abscisic acid (ABA), which then triggers stomatal closure to conserve tissue moisture. Closed stomates, however, also create several physiological dilemmas. Among these, the large CO2 influx required for net photosynthesis will be disrupted. Depleting CO2 in the plant will in turn bias stomatal opening by suppressing ABA sensitivity, which then aggravates transpiration further. We have investigated the molecular basis of how C3 plants resolve this H2 O-CO2 conflicting priority created by stomatal closure. Here, we have identified in Arabidopsis thaliana an early drought-induced spermidine spermine-N(1) -acetyltransferase homolog, which can slow ABA-mediated stomatal closure. Evidence from genetic, biochemical and physiological analyses has revealed that this protein does so by acetylating the metabolite 1,3-diaminopropane (DAP), thereby turning on the latter's intrinsic activity. Acetylated DAP triggers plasma membrane electrical and ion transport properties in an opposite way to those by ABA. Thus in adapting to low soil-water availability, acetyl-DAP could refrain stomates from complete closure to sustain CO2 diffusion to photosynthetic tissues. PMID:24891222

  2. Difference in abscisic acid perception mechanisms between closure induction and opening inhibition of stomata.

    PubMed

    Yin, Ye; Adachi, Yuji; Ye, Wenxiu; Hayashi, Maki; Nakamura, Yoshimasa; Kinoshita, Toshinori; Mori, Izumi C; Murata, Yoshiyuki

    2013-10-01

    Abscisic acid (ABA) induces stomatal closure and inhibits light-induced stomatal opening. The mechanisms in these two processes are not necessarily the same. It has been postulated that the ABA receptors involved in opening inhibition are different from those involved in closure induction. Here, we provide evidence that four recently identified ABA receptors (PYRABACTIN RESISTANCE1 [PYR1], PYRABACTIN RESISTANCE-LIKE1 [PYL1], PYL2, and PYL4) are not sufficient for opening inhibition in Arabidopsis (Arabidopsis thaliana). ABA-induced stomatal closure was impaired in the pyr1/pyl1/pyl2/pyl4 quadruple ABA receptor mutant. ABA inhibition of the opening of the mutant's stomata remained intact. ABA did not induce either the production of reactive oxygen species and nitric oxide or the alkalization of the cytosol in the quadruple mutant, in accordance with the closure phenotype. Whole cell patch-clamp analysis of inward-rectifying K(+) current in guard cells showed a partial inhibition by ABA, indicating that the ABA sensitivity of the mutant was not fully impaired. ABA substantially inhibited blue light-induced phosphorylation of H(+)-ATPase in guard cells in both the mutant and the wild type. On the other hand, in a knockout mutant of the SNF1-related protein kinase, srk2e, stomatal opening and closure, reactive oxygen species and nitric oxide production, cytosolic alkalization, inward-rectifying K(+) current inactivation, and H(+)-ATPase phosphorylation were not sensitive to ABA. PMID:23946352

  3. Karrikins delay soybean seed germination by mediating abscisic acid and gibberellin biogenesis under shaded conditions

    PubMed Central

    Meng, Yongjie; Chen, Feng; Shuai, Haiwei; Luo, Xiaofeng; Ding, Jun; Tang, Shengwen; Xu, Shuanshuan; Liu, Jianwei; Liu, Weiguo; Du, Junbo; Liu, Jiang; Yang, Feng; Sun, Xin; Yong, Taiwen; Wang, Xiaochun; Feng, Yuqi; Shu, Kai; Yang, Wenyu

    2016-01-01

    Karrikins (KAR) are a class of signal compounds, discovered in wildfire smoke, which affect seed germination. Currently, numerous studies have focused on the model plant Arabidopsis in the KAR research field, rather than on crops. Thus the regulatory mechanisms underlying KAR regulation of crop seed germination are largely unknown. Here, we report that KAR delayed soybean seed germination through enhancing abscisic acid (ABA) biosynthesis, while impairing gibberellin (GA) biogenesis. Interestingly, KAR only retarded soybean seed germination under shaded conditions, rather than under dark and white light conditions, which differs from in Arabidopsis. Phytohormone quantification showed that KAR enhanced ABA biogenesis while impairing GA biosynthesis during the seed imbibition process, and subsequently, the ratio of active GA4 to ABA was significantly reduced. Further qRT-PCR analysis showed that the transcription pattern of genes involved in ABA and GA metabolic pathways are consistent with the hormonal measurements. Finally, fluridone, an ABA biogenesis inhibitor, remarkably rescued the delayed-germination phenotype of KAR-treatment; and paclobutrazol, a GA biosynthesis inhibitor, inhibited soybean seed germination. Taken together, these evidences suggest that KAR inhibit soybean seed germination by mediating the ratio between GA and ABA biogenesis. PMID:26902640

  4. Osmotic stress, endogenous abscisic acid and the control of leaf morphology in Hippuris vulgaris L

    NASA Technical Reports Server (NTRS)

    Goliber, T. E.; Feldman, L. J.

    1989-01-01

    Previous reports indicate that heterophyllous aquatic plants can be induced to form aerial-type leaves on submerged shoots when they are grown in exogenous abscisic acid (ABA). This study reports on the relationship between osmotic stress (e.g. the situation encountered by a shoot tip when it grows above the water surface), endogenous ABA (as measured by gas chromatography-electron capture detector) and leaf morphology in the heterophyllous aquatic plant, Hippuris vulgaris. Free ABA could not be detected in submerged shoots of H. vulgaris but in aerial shoots ABA occurred at ca. 40 ng (g fr wt)-1. When submerged shoots were osmotically stressed ABA appeared at levels of 26 to 40 ng (g fr wt)-1. These and other data support two main conclusions: (1) Osmotically stressing a submerged shoot causes the appearance of detectable levels of ABA. (2) The rise of ABA in osmotically stressed submerged shoots in turn induces a change in leaf morphology from the submerged to the aerial form. This corroborates the hypothesis that, in the natural environment, ABA levels rise in response to the osmotic stress encountered when a submerged shoot grows up through the water/air interface and that the increased ABA leads to the production of aerial-type leaves.

  5. Supplementation with Abscisic Acid Reduces Malaria Disease Severity and Parasite Transmission.

    PubMed

    Glennon, Elizabeth K K; Adams, L Garry; Hicks, Derrick R; Dehesh, Katayoon; Luckhart, Shirley

    2016-06-01

    Nearly half of the world's population is at risk for malaria. Increasing drug resistance has intensified the need for novel therapeutics, including treatments with intrinsic transmission-blocking properties. In this study, we demonstrate that the isoprenoid abscisic acid (ABA) modulates signaling in the mammalian host to reduce parasitemia and the formation of transmissible gametocytes and in the mosquito host to reduce parasite infection. Oral ABA supplementation in a mouse model of malaria was well tolerated and led to reduced pathology and enhanced gene expression in the liver and spleen consistent with infection recovery. Oral ABA supplementation also increased mouse plasma ABA to levels that can signal in the mosquito midgut upon blood ingestion. Accordingly, we showed that supplementation of a Plasmodium falciparum-infected blood meal with ABA increased expression of mosquito nitric oxide synthase and reduced infection prevalence in a nitric oxide-dependent manner. Identification of the mechanisms whereby ABA reduces parasite growth in mammals and mosquitoes could shed light on the balance of immunity and metabolism across eukaryotes and provide a strong foundation for clinical translation. PMID:27001761

  6. ABC transporter AtABCG25 is involved in abscisic acid transport and responses

    PubMed Central

    Kuromori, Takashi; Miyaji, Takaaki; Yabuuchi, Hikaru; Shimizu, Hidetada; Sugimoto, Eriko; Kamiya, Asako; Moriyama, Yoshinori; Shinozaki, Kazuo

    2010-01-01

    Abscisic acid (ABA) is one of the most important phytohormones involved in abiotic stress responses, seed maturation, germination, and senescence. ABA is predominantly produced in vascular tissues and exerts hormonal responses in various cells, including guard cells. Although ABA responses require extrusion of ABA from ABA-producing cells in an intercellular ABA signaling pathway, the transport mechanisms of ABA through the plasma membrane remain unknown. Here we isolated an ATP-binding cassette (ABC) transporter gene, AtABCG25, from Arabidopsis by genetically screening for ABA sensitivity. AtABCG25 was expressed mainly in vascular tissues. The fluorescent protein-fused AtABCG25 was localized at the plasma membrane in plant cells. In membrane vesicles derived from AtABCG25-expressing insect cells, AtABCG25 exhibited ATP-dependent ABA transport. The AtABCG25-overexpressing plants showed higher leaf temperatures, implying an influence on stomatal regulation. These results strongly suggest that AtABCG25 is an exporter of ABA and is involved in the intercellular ABA signaling pathway. The presence of the ABA transport mechanism sheds light on the active control of multicellular ABA responses to environmental stresses among plant cells. PMID:20133881

  7. Identification of an abscisic acid transporter by functional screening using the receptor complex as a sensor

    PubMed Central

    Kanno, Yuri; Hanada, Atsushi; Chiba, Yasutaka; Ichikawa, Takanari; Nakazawa, Miki; Matsui, Minami; Koshiba, Tomokazu; Kamiya, Yuji; Seo, Mitsunori

    2012-01-01

    Movement of the plant hormone abscisic acid (ABA) within plants has been documented; however, the molecular mechanisms that regulate ABA transport are not fully understood. By using a modified yeast two-hybrid system, we screened Arabidopsis cDNAs capable of inducing interactions between the ABA receptor PYR/PYL/RCAR and PP2C protein phosphatase under low ABA concentrations. By using this approach, we identified four members of the NRT1/PTR family as candidates for ABA importers. Transport assays in yeast and insect cells demonstrated that at least one of the candidates ABA-IMPORTING TRANSPORTER (AIT) 1, which had been characterized as the low-affinity nitrate transporter NRT1.2, mediates cellular ABA uptake. Compared with WT, the ait1/nrt1.2 mutants were less sensitive to exogenously applied ABA during seed germination and/or postgermination growth, whereas overexpression of AIT1/NRT1.2 resulted in ABA hypersensitivity in the same conditions. Interestingly, the inflorescence stems of ait1/nrt1.2 had a lower surface temperature than those of the WT because of excess water loss from open stomata. We detected promoter activities of AIT1/NRT1.2 around vascular tissues in inflorescence stems, leaves, and roots. These data suggest that the function of AIT1/NRT1.2 as an ABA importer at the site of ABA biosynthesis is important for the regulation of stomatal aperture in inflorescence stems. PMID:22645333

  8. PDR-type ABC transporter mediates cellular uptake of the phytohormone abscisic acid

    PubMed Central

    Kang, Joohyun; Hwang, Jae-Ung; Kim, Yu-Young; Assmann, Sarah M.; Martinoia, Enrico; Lee, Youngsook

    2010-01-01

    Abscisic acid (ABA) is a ubiquitous phytohormone involved in many developmental processes and stress responses of plants. ABA moves within the plant, and intracellular receptors for ABA have been recently identified; however, no ABA transporter has been described to date. Here, we report the identification of the ATP-binding cassette (ABC) transporter Arabidopsis thaliana Pleiotropic drug resistance transporter PDR12 (AtPDR12)/ABCG40 as a plasma membrane ABA uptake transporter. Uptake of ABA into yeast and BY2 cells expressing AtABCG40 was increased, whereas ABA uptake into protoplasts of atabcg40 plants was decreased compared with control cells. In response to exogenous ABA, the up-regulation of ABA responsive genes was strongly delayed in atabcg40 plants, indicating that ABCG40 is necessary for timely responses to ABA. Stomata of loss-of-function atabcg40 mutants closed more slowly in response to ABA, resulting in reduced drought tolerance. Our results integrate ABA-dependent signaling and transport processes and open another avenue for the engineering of drought-tolerant plants. PMID:20133880

  9. The Arabidopsis LYST INTERACTING PROTEIN 5 Acts in Regulating Abscisic Acid Signaling and Drought Response.

    PubMed

    Xia, Zongliang; Huo, Yongjin; Wei, Yangyang; Chen, Qiansi; Xu, Ziwei; Zhang, Wei

    2016-01-01

    Multivesicular bodies (MVBs) are unique endosomes containing vesicles in the lumens and play essential roles in many eukaryotic cellular processes. The Arabidopsis LYST INTERACTING PROTEIN 5 (LIP5), a positive regulator of MVB biogenesis, has critical roles in biotic and abiotic stress responses. However, whether the abscisic acid (ABA) signaling is involved in LIP5-mediated stress response is largely unknown. Here, we report that LIP5 functions in regulating ABA signaling and drought response in Arabidopsis. Analyses of a LIP5 promoter-β-glucuronidase (GUS) construct revealed substantial GUS activity in whole seedlings. The expression of LIP5 was induced by ABA and drought, and overexpression of LIP5 led to ABA hypersensitivity, enhanced stomatal closure, reduced water loss, and, therefore, increased drought tolerance. On the contrary, LIP5 knockdown mutants showed ABA-insensitive phenotypes and reduced drought tolerance; suggesting that LIP5 acts in regulating ABA response. Further analysis using a fluorescent dye revealed that ABA and water stress induced cell endocytosis or vesicle trafficking in a largely LIP5-dependent manner. Furthermore, expression of several drought- or ABA-inducible marker genes was significantly down-regulated in the lip5 mutant seedlings. Collectively, our data suggest that LIP5 positively regulates drought tolerance through ABA-mediated cell signaling. PMID:27313589

  10. Abscisic Acid Determines Basal Susceptibility of Tomato to Botrytis cinerea and Suppresses Salicylic Acid-Dependent Signaling Mechanisms1

    PubMed Central

    Audenaert, Kris; De Meyer, Geert B.; Höfte, Monica M.

    2002-01-01

    Abscisic acid (ABA) is one of the plant hormones involved in the interaction between plants and pathogens. In this work, we show that tomato (Lycopersicon esculentum Mill. cv Moneymaker) mutants with reduced ABA levels (sitiens plants) are much more resistant to the necrotrophic fungus Botrytis cinerea than wild-type (WT) plants. Exogenous application of ABA restored susceptibility to B. cinerea in sitiens plants and increased susceptibility in WT plants. These results indicate that ABA plays a major role in the susceptibility of tomato to B. cinerea. ABA appeared to interact with a functional plant defense response against B. cinerea. Experiments with transgenic NahG tomato plants and benzo(1,2,3)thiadiazole-7-carbothioic acid demonstrated the importance of salicylic acid in the tomato-B. cinerea interaction. In addition, upon infection with B. cinerea, sitiens plants showed a clear increase in phenylalanine ammonia lyase activity, which was not observed in infected WT plants, indicating that the ABA levels in healthy WT tomato plants partly repress phenylalanine ammonia lyase activity. In addition, sitiens plants became more sensitive to benzo(1,2,3)thiadiazole-7-carbothioic acid root treatment. The threshold values for PR1a gene expression declined with a factor 10 to 100 in sitiens compared with WT plants. Thus, ABA appears to negatively modulate the salicylic acid-dependent defense pathway in tomato, which may be one of the mechanisms by which ABA levels determine susceptibility to B. cinerea. PMID:11842153

  11. Abscisic acid regulates root growth under osmotic stress conditions via an interacting hormonal network with cytokinin, ethylene and auxin.

    PubMed

    Rowe, James H; Topping, Jennifer F; Liu, Junli; Lindsey, Keith

    2016-07-01

    Understanding the mechanisms regulating root development under drought conditions is an important question for plant biology and world agriculture. We examine the effect of osmotic stress on abscisic acid (ABA), cytokinin and ethylene responses and how they mediate auxin transport, distribution and root growth through effects on PIN proteins. We integrate experimental data to construct hormonal crosstalk networks to formulate a systems view of root growth regulation by multiple hormones. Experimental analysis shows: that ABA-dependent and ABA-independent stress responses increase under osmotic stress, but cytokinin responses are only slightly reduced; inhibition of root growth under osmotic stress does not require ethylene signalling, but auxin can rescue root growth and meristem size; osmotic stress modulates auxin transporter levels and localization, reducing root auxin concentrations; PIN1 levels are reduced under stress in an ABA-dependent manner, overriding ethylene effects; and the interplay among ABA, ethylene, cytokinin and auxin is tissue-specific, as evidenced by differential responses of PIN1 and PIN2 to osmotic stress. Combining experimental analysis with network construction reveals that ABA regulates root growth under osmotic stress conditions via an interacting hormonal network with cytokinin, ethylene and auxin. PMID:26889752

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

    PubMed Central

    Ding, Zhong-Tao; Zhang, Zhi; Luo, Di; Zhou, Jin-Yan; Zhong, Juan; Yang, Jie; Xiao, Liang; Shu, Dan; Tan, Hong

    2015-01-01

    The phytopathogenic ascomycete Botrytis cinerea produces several secondary metabolites that have biotechnical significance and has been particularly used for S-(+)-abscisic acid production at the industrial scale. To manipulate the expression levels of specific secondary metabolite biosynthetic genes of B. cinerea with Agrobacterium tumefaciens-mediated transformation system, two expression vectors (pCBh1 and pCBg1 with different selection markers) and one RNA silencing vector, pCBSilent1, were developed with the In-Fusion assembly method. Both expression vectors were highly effective in constitutively expressing eGFP, and pCBSilent1 effectively silenced the eGFP gene in B. cinerea. Bcaba4, a gene suggested to participate in ABA biosynthesis in B. cinerea, was then targeted for gene overexpression and RNA silencing with these reverse genetic tools. The overexpression of bcaba4 dramatically induced ABA formation in the B. cinerea wild type strain Bc-6, and the gene silencing of bcaba4 significantly reduced ABA-production in an ABA-producing B. cinerea strain. PMID:25955649

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

    PubMed

    Ding, Zhong-Tao; Zhang, Zhi; Luo, Di; Zhou, Jin-Yan; Zhong, Juan; Yang, Jie; Xiao, Liang; Shu, Dan; Tan, Hong

    2015-01-01

    The phytopathogenic ascomycete Botrytis cinerea produces several secondary metabolites that have biotechnical significance and has been particularly used for S-(+)-abscisic acid production at the industrial scale. To manipulate the expression levels of specific secondary metabolite biosynthetic genes of B. cinerea with Agrobacterium tumefaciens-mediated transformation system, two expression vectors (pCBh1 and pCBg1 with different selection markers) and one RNA silencing vector, pCBSilent1, were developed with the In-Fusion assembly method. Both expression vectors were highly effective in constitutively expressing eGFP, and pCBSilent1 effectively silenced the eGFP gene in B. cinerea. Bcaba4, a gene suggested to participate in ABA biosynthesis in B. cinerea, was then targeted for gene overexpression and RNA silencing with these reverse genetic tools. The overexpression of bcaba4 dramatically induced ABA formation in the B. cinerea wild type strain Bc-6, and the gene silencing of bcaba4 significantly reduced ABA-production in an ABA-producing B. cinerea strain. PMID:25955649

  14. Abscisic Acid: A Phytohormone and Mammalian Cytokine as Novel Pharmacon with Potential for Future Development into Clinical Applications.

    PubMed

    Sakthivel, Priya; Sharma, Niharika; Klahn, Philipp; Gereke, Marcus; Bruder, Dunja

    2016-01-01

    The isoprenoid stress-associated phytohormone abscisic acid (ABA) has recently been recognized to possess multifaceted biological functions in mammals and to exert potent curative effects in a number of clinically relevant human diseases. Studies with human specimens have unequivocally shown that ABA retains its stress-related functional attributes, previously identified in plants, which contribute to enhanced inflammatory defense mechanisms in mammals. Besides, studies performed in animal models revealed prominent anti-inflammatory properties of ABA as indicated by a marked reduction of immune cell infiltrates at the sites of inflammation. Thus, ABA treatment ultimately leads to the profound improvement of both non-communicable and communicable diseases which are associated with an overall alleviated course of inflammation. In addition to its action on the mammalian immune system, ABA was also shown to exert diverse physiological functions on non-immune components. One of the most remarkable features of ABA is to stimulate and expand mesenchymal stem cells, which may open a new avenue for its potential use in the field of regenerative medicine. Furthermore, ABA has been reported to play an important role in the maintenance of glycemic control. In this review, we summarize current understanding of the significance of ABA in the mammalian system, its prophylactic and therapeutic effects in various disease settings and the future directions for the development of ABA as novel drug candidate for the improved treatment of inflammatory and infectious human diseases. PMID:27048335

  15. LTP3 contributes to disease susceptibility in Arabidopsis by enhancing abscisic acid (ABA) biosynthesis.

    PubMed

    Gao, Shan; Guo, Wenya; Feng, Wen; Liu, Liang; Song, Xiaorui; Chen, Jian; Hou, Wei; Zhu, Hongxia; Tang, Saijun; Hu, Jian

    2016-04-01

    Several plant lipid transfer proteins (LTPs) act positively in plant disease resistance. Here, we show that LTP3 (At5g59320), a pathogen and abscisic acid (ABA)-induced gene, negatively regulates plant immunity in Arabidopsis. The overexpression of LTP3 (LTP3-OX) led to an enhanced susceptibility to virulent bacteria and compromised resistance to avirulent bacteria. On infection of LTP3-OX plants with Pseudomonas syringae pv. tomato, genes involved in ABA biosynthesis, NCED3 and AAO3, were highly induced, whereas salicylic acid (SA)-related genes, ICS1 and PR1, were down-regulated. Accordingly, in LTP3-OX plants, we observed increased ABA levels and decreased SA levels relative to the wild-type. We also showed that the LTP3 overexpression-mediated enhanced susceptibility was partially dependent on AAO3. Interestingly, loss of function of LTP3 (ltp3-1) did not affect ABA pathways, but resulted in PR1 gene induction and elevated SA levels, suggesting that LTP3 can negatively regulate SA in an ABA-independent manner. However, a double mutant consisting of ltp3-1 and silent LTP4 (ltp3/ltp4) showed reduced susceptibility to Pseudomonas and down-regulation of ABA biosynthesis genes, suggesting that LTP3 acts in a redundant manner with its closest homologue LTP4 by modulating the ABA pathway. Taken together, our data show that LTP3 is a novel negative regulator of plant immunity which acts through the manipulation of the ABA-SA balance. PMID:26123657

  16. Abscisic Acid Is a General Negative Regulator of Arabidopsis Axillary Bud Growth1[OPEN

    PubMed Central

    Yao, Chi; Finlayson, Scott A.

    2015-01-01

    Branching is an important process controlled by intrinsic programs and by environmental signals transduced by a variety of plant hormones. Abscisic acid (ABA) was previously shown to mediate Arabidopsis (Arabidopsis thaliana) branching responses to the ratio of red light (R) to far-red light (FR; an indicator of competition) by suppressing bud outgrowth from lower rosette positions under low R:FR. However, the role of ABA in regulating branching more generally was not investigated. This study shows that ABA restricts lower bud outgrowth and promotes correlative inhibition under both high and low R:FR. ABA was elevated in buds exhibiting delayed outgrowth resulting from bud position and low R:FR and decreased in elongating buds. ABA was reduced in lower buds of hyperbranching mutants deficient in auxin signaling (AUXIN RESISTANT1), MORE AXILLARY BRANCHING (MAX) signaling (MAX2), and BRANCHED1 (BRC1) function, and partial suppression of branch elongation in these mutants by exogenous ABA suggested that ABA may act downstream of these components. Bud BRC1 expression was not altered by exogenous ABA, consistent with a downstream function for ABA. However, the expression of genes encoding the indole-3-acetic acid (IAA) biosynthesis enzyme TRYPTOPHAN AMINOTRANSFERASE OF ARABIDOPSIS1, the auxin transporter PIN-FORMED1, and the cell cycle genes CYCLIN A2;1 and PROLIFERATING CELL NUCLEAR ANTIGEN1 in buds was suppressed by ABA, suggesting that it may inhibit bud growth in part by suppressing elements of the cell cycle machinery and bud-autonomous IAA biosynthesis and transport. ABA was found to suppress bud IAA accumulation, thus confirming this aspect of its action. PMID:26149576

  17. Regulation of auxin, abscisic acid and salicylic acid levels by ascorbate application under heat stress in sensitive and tolerant maize leaves.

    PubMed

    Dinler, Burcu Seckin; Demir, Emel; Kompe, Yasemin Ozdener

    2014-12-01

    In the present study, the effect of ascorbic acid (5 mM) on some physiological parameters and three hormones (auxin, abscisic acid, salicylic acid) was determined under heat stress (40 °C) in maize tolerant cv. (MAY 69) and sensitive cv. SHEMAL (SH) at 0 h, 4 h and 8 h. Heat stress reduced total chlorophyll content (CHL), relative water content (RWC) and stomatal conductance (gs) in SH but did not lead to changes in MAY 69 at 4 h and 8 h. However, pretreatment with ascorbic acid increased (CHL), (RWC) and (gs) in SH under heat stress while it reduced MDA content significantly in both cv. We also observed that heat stress led to a reduction in SA level but increased ABA and IAA levels in SH, whereas it increased SA and IAA levels but did not change ABA level in MAY 69 at 4 h. Furthermore, in SH, ASC application under heat stress increased SA level and decreased IAA and ABA levels at 4 h, but it had no effect on SA and ABA at 8 h. PMID:25475985

  18. The Receptor Kinase IMPAIRED OOMYCETE SUSCEPTIBILITY1 Attenuates Abscisic Acid Responses in Arabidopsis1[C][W

    PubMed Central

    Hok, Sophie; Allasia, Valérie; Andrio, Emilie; Naessens, Elodie; Ribes, Elsa; Panabières, Franck; Attard, Agnès; Ris, Nicolas; Clément, Mathilde; Barlet, Xavier; Marco, Yves; Grill, Erwin; Eichmann, Ruth; Weis, Corina; Hückelhoven, Ralph; Ammon, Alexandra; Ludwig-Müller, Jutta; Voll, Lars M.; Keller, Harald

    2014-01-01

    In plants, membrane-bound receptor kinases are essential for developmental processes, immune responses to pathogens and the establishment of symbiosis. We previously identified the Arabidopsis (Arabidopsis thaliana) receptor kinase IMPAIRED OOMYCETE SUSCEPTIBILITY1 (IOS1) as required for successful infection with the downy mildew pathogen Hyaloperonospora arabidopsidis. We report here that IOS1 is also required for full susceptibility of Arabidopsis to unrelated (hemi)biotrophic filamentous oomycete and fungal pathogens. Impaired susceptibility in the absence of IOS1 appeared to be independent of plant defense mechanism. Instead, we found that ios1-1 plants were hypersensitive to the plant hormone abscisic acid (ABA), displaying enhanced ABA-mediated inhibition of seed germination, root elongation, and stomatal opening. These findings suggest that IOS1 negatively regulates ABA signaling in Arabidopsis. The expression of ABA-sensitive COLD REGULATED and RESISTANCE TO DESICCATION genes was diminished in Arabidopsis during infection. This effect on ABA signaling was alleviated in the ios1-1 mutant background. Accordingly, ABA-insensitive and ABA-hypersensitive mutants were more susceptible and resistant to oomycete infection, respectively, showing that the intensity of ABA signaling affects the outcome of downy mildew disease. Taken together, our findings suggest that filamentous (hemi)biotrophs attenuate ABA signaling in Arabidopsis during the infection process and that IOS1 participates in this pathogen-mediated reprogramming of the host. PMID:25274985

  19. Nitric oxide negatively regulates abscisic acid signaling in guard cells by S-nitrosylation of OST1

    PubMed Central

    Wang, Pengcheng; Du, Yanyan; Hou, Yueh-Ju; Zhao, Yang; Hsu, Chuan-Chih; Yuan, Feijuan; Zhu, Xiaohong; Tao, W. Andy; Song, Chun-Peng; Zhu, Jian-Kang

    2015-01-01

    The phytohormone abscisic acid (ABA) plays important roles in plant development and adaptation to environmental stress. ABA induces the production of nitric oxide (NO) in guard cells, but how NO regulates ABA signaling is not understood. Here, we show that NO negatively regulates ABA signaling in guard cells by inhibiting open stomata 1 (OST1)/sucrose nonfermenting 1 (SNF1)-related protein kinase 2.6 (SnRK2.6) through S-nitrosylation. We found that SnRK2.6 is S-nitrosylated at cysteine 137, a residue adjacent to the kinase catalytic site. Dysfunction in the S-nitrosoglutathione (GSNO) reductase (GSNOR) gene in the gsnor1-3 mutant causes NO overaccumulation in guard cells, constitutive S-nitrosylation of SnRK2.6, and impairment of ABA-induced stomatal closure. Introduction of the Cys137 to Ser mutated SnRK2.6 into the gsnor1-3/ost1-3 double-mutant partially suppressed the effect of gsnor1-3 on ABA-induced stomatal closure. A cysteine residue corresponding to Cys137 of SnRK2.6 is present in several yeast and human protein kinases and can be S-nitrosylated, suggesting that the S-nitrosylation may be an evolutionarily conserved mechanism for protein kinase regulation. PMID:25550508

  20. Abscisic acid and stress treatment are essential for the acquisition of embryogenic competence by carrot somatic cells.

    PubMed

    Kikuchi, Akira; Sanuki, Nobuya; Higashi, Katsumi; Koshiba, Tomokazu; Kamada, Hiroshi

    2006-03-01

    Studies of carrot embryogenesis have suggested that abscisic acid (ABA) is involved in somatic embryogenesis. A relationship between endogenous ABA and the induction of somatic embryogenesis was demonstrated using stress-induced system of somatic embryos. The embryonic-specific genes C-ABI3 and embryogenic cell proteins (ECPs) were expressed during stress treatment prior to the formation of somatic embryos. The stress-induction system for embryogenesis was clearly distinguished by two phases: the acquisition of embryogenic competence and the formation of a somatic embryo. Somatic embryo formation was inhibited by the application of fluridone (especially at 10(-4) M), a potent inhibitor of ABA biosynthesis, during stress treatment. The inhibitory effect of fluridone was nullified by the simultaneous application of fluridone and ABA. The level of endogenous ABA increased transiently during stress. However, somatic embryogenesis was not significantly induced by the application of only ABA to the endogenous level, in the absence of stress. These results suggest that the induction of somatic embryogenesis, in particular the acquisition of embryogenic competence, is caused not only by the presence of ABA but also by physiological responses that are directly controlled by stresses. PMID:16160844

  1. Drying rate and dehydrin synthesis associated with abscisic acid-induced dehydration tolerance in Spathoglottis plicata orchidaceae protocorms.

    PubMed

    Wang, Xing-Jun; Loh, Chiang-Shiong; Yeoh, Hock-Hin; Sun, Wendell Q

    2002-03-01

    Dehydration tolerance of in vitro orchid protocorms was investigated under controlled drying conditions and after abscisic acid (ABA) pretreatment. Protocorms were obtained by germinating seeds on Murashige and Skoog (MS) medium containing 10% (v/v) coconut water, 2% (w/v) sucrose and 0.8% (w/v) agar, and were dehydrated in relative humidities (RH) ranging from 7% to 93% at 25 degrees C. The critical water content of dehydration tolerance was determined, using the electrolyte leakage method. Drying rate affected the critical water content. Slow drying under high RH conditions achieved the greatest tolerance to dehydration. ABA pretreatment decreased the drying rate of protocorms, and increased dehydration tolerance. Improved tolerance to dehydration after ABA treatment was correlated with the effect of ABA on drying rate of protocorms. When critical water content of protocorms dried under different RH was plotted as a function of actual drying rate, no significant difference in tolerance to dehydration was observed between ABA-treated and control protocorms. ABA pretreatment and dehydration of orchid protocorms induced the synthesis of dehydrin, especially under the slow drying conditions. ABA pretreatment also promoted dry matter accumulation such as carbohydrates and soluble proteins and increased the concentration of K(+) and Na(+) ions in protocorms. The ABA-induced decrease in drying rate was correlated with lower osmotic potential, the enhanced maturity of protocorms and the accumulation of dehydrin in protocorms during pretreatment. PMID:11847254

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

    PubMed Central

    Galka, Marek M.; Rajagopalan, Nandhakishore; Buhrow, Leann M.; Nelson, Ken M.; Switala, Jacek; Cutler, Adrian J.; Palmer, David R. J.; Loewen, Peter C.; Abrams, Suzanne R.; Loewen, Michele C.

    2015-01-01

    Abscisic acid ((+)-ABA) is a phytohormone involved in the modulation of developmental processes and stress responses in plants. A chemical proteomics approach using an ABA mimetic probe was combined with in vitro assays, isothermal titration calorimetry (ITC), x-ray crystallography and in silico modelling to identify putative (+)-ABA binding-proteins in crude extracts of Arabidopsis thaliana. Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) was identified as a putative ABA-binding protein. Radiolabelled-binding assays yielded a Kd of 47 nM for (+)-ABA binding to spinach Rubisco, which was validated by ITC, and found to be similar to reported and experimentally derived values for the native ribulose-1,5-bisphosphate (RuBP) substrate. Functionally, (+)-ABA caused only weak inhibition of Rubisco catalytic activity (Ki of 2.1 mM), but more potent inhibition of Rubisco activation (Ki of ~ 130 μM). Comparative structural analysis of Rubisco in the presence of (+)-ABA with RuBP in the active site revealed only a putative low occupancy (+)-ABA binding site on the surface of the large subunit at a location distal from the active site. However, subtle distortions in electron density in the binding pocket and in silico docking support the possibility of a higher affinity (+)-ABA binding site in the RuBP binding pocket. Overall we conclude that (+)-ABA interacts with Rubisco. While the low occupancy (+)-ABA binding site and weak non-competitive inhibition of catalysis may not be relevant, the high affinity site may allow ABA to act as a negative effector of Rubisco activation. PMID:26197050

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

    PubMed Central

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

    1993-01-01

    The responses to low temperature were determined for two species of cacti sensitive to freezing, Ferocactus viridescens and Opuntia ficus-indica, and a cold hardy species, Opuntia fragilis. Fourteen days after shifting the plants from day/night air temperatures of 30/20[deg]C to 10/0[deg]C, the chlorenchyma water content decreased only for O. fragilis. This temperature shift caused the freezing tolerance (measured by vital stain uptake) of chlorenchyma cells to be enhanced only by about 2.0[deg]C for F. viridescens and O. ficus-indica but by 14.6[deg]C for O. fragilis. Also, maintenance of high water content by injection of water into plants at 10/0[deg]C reversed the acclimation. The endogenous abscisic acid (ABA) concentration was below 0.4 pmol g-1 fresh weight at 30/20[deg]C, but after 14 d at 10/0[deg]C it increased to 84 pmol g-1 fresh weight for O. ficus-indica and to 49 pmol g-1 fresh weight for O. fragilis. Four days after plants were sprayed with 7.5 x 10-5 M ABA at 30/20[deg]C, freezing tolerance was enhanced by 0.5[deg]C for F. viridescens, 4.1[deg]C for O. ficus-indica, and 23.4[deg]C for O. fragilis. Moreover, the time course for the change in freezing tolerance over 14 d was similar for plants shifted to low temperatures as for plants treated with exogenous ABA at moderate temperatures. Decreases in plant water content and increases in ABA concentration may be important for low-temperature acclimation by cacti, especially O. fragilis, which is widely distributed in Canada and the United States. PMID:12231985

  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. PMID:27446121

  6. NFX1-LIKE2 (NFXL2) Suppresses Abscisic Acid Accumulation and Stomatal Closure in Arabidopsis thaliana

    PubMed Central

    Lisso, Janina; Schröder, Florian; Fisahn, Joachim; Müssig, Carsten

    2011-01-01

    The NFX1-LIKE1 (NFXL1) and NFXL2 genes were identified as regulators of salt stress responses. The NFXL1 protein is a nuclear factor that positively affects adaptation to salt stress. The nfxl1-1 loss-of-function mutant displayed reduced survival rates under salt and high light stress. In contrast, the nfxl2-1 mutant, defective in the NFXL2 gene, and NFXL2-antisense plants exhibited enhanced survival under these conditions. We show here that the loss of NFXL2 function results in abscisic acid (ABA) overaccumulation, reduced stomatal conductance, and enhanced survival under drought stress. The nfxl2-1 mutant displayed reduced stomatal aperture under all conditions tested. Fusicoccin treatment, exposition to increasing light intensities, and supply of decreasing CO2 concentrations demonstrated full opening capacity of nfxl2-1 stomata. Reduced stomatal opening presumably is a consequence of elevated ABA levels. Furthermore, seedling growth, root growth, and stomatal closure were hypersensitive to exogenous ABA. The enhanced ABA responses may contribute to the improved drought stress resistance of the mutant. Three NFXL2 splice variants were cloned and named NFXL2-78, NFXL2-97, and NFXL2-100 according to the molecular weight of the putative proteins. Translational fusions to the green fluorescent protein suggest nuclear localisation of the NFXL2 proteins. Stable expression of the NFXL2-78 splice variant in nfxl2-1 plants largely complemented the mutant phenotype. Our data show that NFXL2 controls ABA levels and suppresses ABA responses. NFXL2 may prevent unnecessary and costly stress adaptation under favourable conditions. PMID:22073231

  7. An Ancestral Role for CONSTITUTIVE TRIPLE RESPONSE1 Proteins in Both Ethylene and Abscisic Acid Signaling.

    PubMed

    Yasumura, Yuki; Pierik, Ronald; Kelly, Steven; Sakuta, Masaaki; Voesenek, Laurentius A C J; Harberd, Nicholas P

    2015-09-01

    Land plants have evolved adaptive regulatory mechanisms enabling the survival of environmental stresses associated with terrestrial life. Here, we focus on the evolution of the regulatory CONSTITUTIVE TRIPLE RESPONSE1 (CTR1) component of the ethylene signaling pathway that modulates stress-related changes in plant growth and development. First, we compare CTR1-like proteins from a bryophyte, Physcomitrella patens (representative of early divergent land plants), with those of more recently diverged lycophyte and angiosperm species (including Arabidopsis [Arabidopsis thaliana]) and identify a monophyletic CTR1 family. The fully sequenced P. patens genome encodes only a single member of this family (PpCTR1L). Next, we compare the functions of PpCTR1L with that of related angiosperm proteins. We show that, like angiosperm CTR1 proteins (e.g. AtCTR1 of Arabidopsis), PpCTR1L modulates downstream ethylene signaling via direct interaction with ethylene receptors. These functions, therefore, likely predate the divergence of the bryophytes from the land-plant lineage. However, we also show that PpCTR1L unexpectedly has dual functions and additionally modulates abscisic acid (ABA) signaling. In contrast, while AtCTR1 lacks detectable ABA signaling functions, Arabidopsis has during evolution acquired another homolog that is functionally distinct from AtCTR1. In conclusion, the roles of CTR1-related proteins appear to have functionally diversified during land-plant evolution, and angiosperm CTR1-related proteins appear to have lost an ancestral ABA signaling function. Our study provides new insights into how molecular events such as gene duplication and functional differentiation may have contributed to the adaptive evolution of regulatory mechanisms in plants. PMID:26243614

  8. Abscisic acid and stress signals induce Viviparous1 expression in seed and vegetative tissues of maize.

    PubMed

    Cao, Xueyuan; Costa, Liliana M; Biderre-Petit, Corinne; Kbhaya, Bouchab; Dey, Nrisingha; Perez, Pascual; McCarty, Donald R; Gutierrez-Marcos, Jose F; Becraft, Philip W

    2007-02-01

    Viviparous1 (Vp1) encodes a B3 domain-containing transcription factor that is a key regulator of seed maturation in maize (Zea mays). However, the mechanisms of Vp1 regulation are not well understood. To examine physiological factors that may regulate Vp1 expression, transcript levels were monitored in maturing embryos placed in culture under different conditions. Expression of Vp1 decreased after culture in hormone-free medium, but was induced by salinity or osmotic stress. Application of exogenous abscisic acid (ABA) also induced transcript levels within 1 h in a dose-dependent manner. The Vp1 promoter fused to beta-glucuronidase or green fluorescent protein reproduced the endogenous Vp1 expression patterns in transgenic maize plants and also revealed previously unknown expression domains of Vp1. The Vp1 promoter is active in the embryo and aleurone cells of developing seeds and, upon drought stress, was also found in phloem cells of vegetative tissues, including cobs, leaves, and stems. Sequence analysis of the Vp1 promoter identified a potential ABA-responsive complex, consisting of an ACGT-containing ABA response element (ABRE) and a coupling element 1-like motif. Electrophoretic mobility shift assay confirmed that the ABRE and putative coupling element 1 components specifically bound proteins in embryo nuclear protein extracts. Treatment of embryos in hormone-free Murashige and Skoog medium blocked the ABRE-protein interaction, whereas exogenous ABA or mannitol treatment restored this interaction. Our data support a model for a VP1-dependent positive feedback mechanism regulating Vp1 expression during seed maturation. PMID:17208960

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

    PubMed

    Young, L M; Evans, M L

    1996-01-01

    Because both abscisic acid (ABA) and auxin (IAA) have been suggested as possible chemical mediators of differential growth during root gravitropism, we compared with redistribution of label from applied 3H-IAA and 3H-ABA during maize root gravitropism and examined the relative basipetal movement of 3H-IAA and 3H-ABA applied to the caps of vertical roots. Lateral movement of 3H-ABA across the tips of vertical roots was non-polar and about 2-fold greater than lateral movement of 3H-IAA (also non-polar). The greater movement of ABA was not due to enhanced uptake since the uptake of 3H-IAA was greater than that of 3H-ABA. Basipetal movement of label from 3H-IAA or 3H-ABA applied to the root cap was determined by measuring radioactivity in successive 1 mm sections behind the tip 90 minutes after application. ABA remained largely in the first mm (point of application) whereas IAA was concentrated in the region 2-4 mm from the tip with substantial levels found 7-8 mm from the tip. Pretreatment with inhibitors of polar auxin transport decreased both gravicurvature and the basipetal movement of IAA. When roots were placed horizontally, the movement of 3H-IAA from top to bottom across the cap was enhanced relative to movement from bottom to top whereas the pattern of movement of label from 3H-ABA was unaffected. These results are consistent with the hypothesis that IAA plays a role in root gravitropism but contrary to the idea that gravi-induced asymmetric distribution of ABA contributes to the response. PMID:11540494

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

    NASA Technical Reports Server (NTRS)

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

    1996-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Moore, R.; Dickey, K.

    1985-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

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

  13. Reciprocity between abscisic acid and ethylene at the onset of berry ripening and after harvest

    PubMed Central

    2010-01-01

    Background The ripening of grape berry is generally regulated by abscisic acid (ABA), and has no relationship with ethylene function. However, functional interaction and synergism between ABA and ethylene during the beginning of grape berry ripening (véraison) has been found recently. Results The expressions of VvNCED1 encoding 9-cis-epoxycarotenoid dioxygenase (NCED) and VvGT encoding ABA glucosyltransferase were all increased rapidly at the stage of véraison and reached the highest level at 9th week after full bloom. However, VvCYP1 encoding ABA 8'-hydroxylase and VvβG1 encoding berry β-glucosidase are different, whose expression peak appeared at the 10th week after full bloom and in especial VvβG1 remained at a high level till harvest. The VvACO1 encoding 1-aminocyclopropane-1-carboxylic acid (ACC) oxidase, the VvETR2 (ethylene response 2) and VvCTR1 (constitutive triple response 1) had a transient expression peak at pre-véraison, while the VvEIN4 (ethylene insensitive 4) expression gradually increased from the véraison to one week before harvest stage. The above mentioned changes happened again in the berry after harvest. At one week before véraison, double block treatment with NiCl2 plus 1-methylcyclopropene (1-MCP) not only inhibited the release of ethylene and the expression of related genes but also suppressed the transcription of VvNCED1 and the synthesis of ABA which all might result in inhibiting the fruit ripening onset. Treatment with ABA could relieve the double block and restore fruit ripening course. However, after harvest, double block treatment with NiCl2 plus 1-MCP could not suppress the transcription of VvNCED1 and the accumulation of ABA, and also could not inhibit the start of fruit senescence. Conclusion The trace endogenous ethylene induces the transcription of VvNCED1 and then the generation of ABA followed. Both ethylene and ABA are likely to be important and their interplaying may be required to start the process of berry ripening

  14. Abscisic acid-induced gene expression in the liverwort Marchantia polymorpha is mediated by evolutionarily conserved promoter elements.

    PubMed

    Ghosh, Totan K; Kaneko, Midori; Akter, Khaleda; Murai, Shuhei; Komatsu, Kenji; Ishizaki, Kimitsune; Yamato, Katsuyuki T; Kohchi, Takayuki; Takezawa, Daisuke

    2016-04-01

    Abscisic acid (ABA) is a phytohormone widely distributed among members of the land plant lineage (Embryophyta), regulating dormancy, stomata closure and tolerance to environmental stresses. In angiosperms (Magnoliophyta), ABA-induced gene expression is mediated by promoter elements such as the G-box-like ACGT-core motifs recognized by bZIP transcription factors. In contrast, the mode of regulation by ABA of gene expression in liverworts (Marchantiophyta), representing one of the earliest diverging land plant groups, has not been elucidated. In this study, we used promoters of the liverwort Marchantia polymorpha dehydrin and the wheat Em genes fused to the β-glucuronidase (GUS) reporter gene to investigate ABA-induced gene expression in liverworts. Transient assays of cultured cells of Marchantia indicated that ACGT-core motifs proximal to the transcription initiation site play a role in the ABA-induced gene expression. The RY sequence recognized by B3 transcriptional regulators was also shown to be responsible for the ABA-induced gene expression. In transgenic Marchantia plants, ABA treatment elicited an increase in GUS expression in young gemmalings, which was abolished by simultaneous disruption of the ACGT-core and RY elements. ABA-induced GUS expression was less obvious in mature thalli than in young gemmalings, associated with reductions in sensitivity to exogenous ABA during gametophyte growth. In contrast, lunularic acid, which had been suggested to function as an ABA-like substance, had no effect on GUS expression. The results demonstrate the presence of ABA-specific response mechanisms mediated by conserved cis-regulatory elements in liverworts, implying that the mechanisms had been acquired in the common ancestors of embryophytes. PMID:26456006

  15. Phytochrome A and B Function Antagonistically to Regulate Cold Tolerance via Abscisic Acid-Dependent Jasmonate Signaling1[OPEN

    PubMed Central

    Guo, Zhixin; Li, Huizi; Wang, Mengmeng; Zhou, Jie; Xia, Xiaojian; Shi, Kai; Yu, Jingquan

    2016-01-01

    Light signaling and phytohormones both influence plant growth, development, and stress responses; however, cross talk between these two signaling pathways in response to cold remains underexplored. Here, we report that far-red light (FR) and red light (R) perceived by phytochrome A (phyA) and phyB positively and negatively regulated cold tolerance, respectively, in tomato (Solanum lycopersicum), which were associated with the regulation of levels of phytohormones such as abscisic acid (ABA) and jasmonic acid (JA) and transcript levels of ABA- and JA-related genes and the C-REPEAT BINDING FACTOR (CBF) stress signaling pathway genes. A reduction in the R/FR ratio did not alter cold tolerance, ABA and JA accumulation, and transcript levels of ABA- and JA-related genes and the CBF pathway genes in phyA mutant plants; however, those were significantly increased in wild-type and phyB plants with the reduction in the R/FR ratio. Even though low R/FR treatments did not confer cold tolerance in ABA-deficient (notabilis [not]) and JA-deficient (prosystemin-mediated responses2 [spr2]) mutants, it up-regulated ABA accumulation and signaling in the spr2 mutant, with no effect on JA levels and signaling in the not mutant. Foliar application of ABA and JA further confirmed that JA functioned downstream of ABA to activate the CBF pathway in light quality-mediated cold tolerance. It is concluded that phyA and phyB function antagonistically to regulate cold tolerance that essentially involves FR light-induced activation of phyA to induce ABA signaling and, subsequently, JA signaling, leading to an activation of the CBF pathway and a cold response in tomato plants. PMID:26527654

  16. Spatio-temporal changes in endogenous abscisic acid contents during etiolated growth and photomorphogenesis in tomato seedlings

    PubMed Central

    Humplík, Jan F; Turečková, Veronika; Fellner, Martin; Bergougnoux, Véronique

    2015-01-01

    The role of abscisic acid (ABA) during early development was investigated in tomato seedlings. The endogenous content of ABA in particular organs was analyzed in seedlings grown in the dark and under blue light. Our results showed that in dark-grown seedlings, the ABA accumulation was maximal in the cotyledons and elongation zone of hypocotyl, whereas under blue-light, the ABA content was distinctly reduced. Our data are consistent with the conclusion that ABA promotes the growth of etiolated seedlings and the results suggest that ABA plays an inhibitory role in de-etiolation and photomorphogenesis in tomato. PMID:26322576

  17. The Basic Leucine Zipper Transcription Factor ABSCISIC ACID RESPONSE ELEMENT-BINDING FACTOR2 Is an Important Transcriptional Regulator of Abscisic Acid-Dependent Grape Berry Ripening Processes1[W][OPEN

    PubMed Central

    Nicolas, Philippe; Lecourieux, David; Kappel, Christian; Cluzet, Stéphanie; Cramer, Grant; Delrot, Serge; Lecourieux, Fatma

    2014-01-01

    In grape (Vitis vinifera), abscisic acid (ABA) accumulates during fruit ripening and is thought to play a pivotal role in this process, but the molecular basis of this control is poorly understood. This work characterizes ABSCISIC ACID RESPONSE ELEMENT-BINDING FACTOR2 (VvABF2), a grape basic leucine zipper transcription factor belonging to a phylogenetic subgroup previously shown to be involved in ABA and abiotic stress signaling in other plant species. VvABF2 transcripts mainly accumulated in the berry, from the onset of ripening to the harvesting stage, and were up-regulated by ABA. Microarray analysis of transgenic grape cells overexpressing VvABF2 showed that this transcription factor up-regulates and/or modifies existing networks related to ABA responses. In addition, grape cells overexpressing VvABF2 exhibited enhanced responses to ABA treatment compared with control cells. Among the VvABF2-mediated responses highlighted in this study, the synthesis of phenolic compounds and cell wall softening were the most strongly affected. VvABF2 overexpression strongly increased the accumulation of stilbenes that play a role in plant defense and human health (resveratrol and piceid). In addition, the firmness of fruits from tomato (Solanum lycopersicum) plants overexpressing VvABF2 was strongly reduced. These data indicate that VvABF2 is an important transcriptional regulator of ABA-dependent grape berry ripening. PMID:24276949

  18. Abscisic Acid Suppression of Phenylalanine Ammonia-Lyase Activity and mRNA, and Resistance of Soybeans to Phytophthora megasperma f.sp. glycinea1

    PubMed Central

    Ward, Edmund W. B.; Cahill, David M.; Bhattacharyya, Madan K.

    1989-01-01

    Etiolated hypocotyls of the resistant soybean (Glycine max [L.] Merr.) cultivar Harosoy 63 became susceptible to Phytophthora megasperma (Drechs.) f.sp. glycinea (Hildeb.) Kuan and Erwin race 1 after treatment with abscisic acid. Susceptibility was expressed by increases in lesion size and a major decrease in accumulation of the isoflavonoid phytoalexin, glyceollin. In untreated hypocotyls, activity of phenylalanine ammonia-lyase and accumulation of mRNA for this enzyme increased rapidly after infection, but these increases were suppressed in abscisic acid-treated hypocotyls. The results suggest the possibility that biosynthesis of glyceollin in the resistance response of soybeans may be controlled at the transcriptional level by changes in abscisic acid concentrations caused by infection. Images Figure 2 PMID:16667002

  19. Role of arabidopsis MYC and MYB homologs in drought- and abscisic acid-regulated gene expression.

    PubMed Central

    Abe, H; Yamaguchi-Shinozaki, K; Urao, T; Iwasaki, T; Hosokawa, D; Shinozaki, K

    1997-01-01

    In Arabidopsis, the induction of a dehydration-responsive gene, rd22, is mediated by abscisic acid (ABA) and requires protein biosynthesis for ABA-dependent gene expression. Previous experiments established that a 67-bp DNA fragment of the rd22 promoter is sufficient for dehydration- and ABA-induced gene expression and that this DNA fragment contains two closely located putative recognition sites for the basic helix-loop-helix protein MYC and one putative recognition site for MYB. We have carefully analyzed the 67-bp region of the rd22 promoter in transgenic tobacco plants and found that both the first MYC site and the MYB recognition site function as cis-acting elements in the dehydration-induced expression of the rd22 gene. A cDNA encoding a MYC-related DNA binding protein was isolated by DNA-ligand binding screening, using the 67-bp region as a probe, and designated rd22BP1. The rd22BP1 cDNA encodes a 68-kD protein that has a typical DNA binding domain of a basic region helix-loop-helix leucine zipper motif in MYC-related transcription factors. The rd22BP1 protein binds specifically to the first MYC recognition site in the 67-bp fragment. RNA gel blot analysis revealed that transcription of the rd22BP1 gene is induced by dehydration stress and ABA treatment, and its induction precedes that of rd22. We have reported a drought- and ABA-inducible gene that encodes the MYB-related protein ATMYB2. In a transient transactivation experiment using Arabidopsis leaf protoplasts, we demonstrated that both the rd22BP1 and ATMYB2 proteins activate transcription of the rd22 promoter fused to the beta-glucuronidase reporter gene. These results indicate that both the rd22BP1 (MYC) and ATMYB2 (MYB) proteins function as transcriptional activators in the dehydration- and ABA-inducible expression of the rd22 gene. PMID:9368419

  20. Root Growth Maintenance at Low Water Potentials (Increased Activity of Xyloglucan Endotransglycosylase and Its Possible Regulation by Abscisic Acid).

    PubMed Central

    Wu, Y.; Spollen, W. G.; Sharp, R. E.; Hetherington, P. R.; Fry, S. C.

    1994-01-01

    Previous work suggested that an increase in cell wall-loosening contributes to the maintenance of maize (Zea mays L.) primary root elongation at low water potentials ([psi]w). It was also shown that root elongation at low [psi]w requires increased levels of abscisic acid (ABA). In this study we investigated the effects of low [psi]w and ABA status on xyloglucan endotransglycosylase (XET) activity in the root elongation zone. XET is believed to contribute to wall-loosening by reversibly cleaving xyloglucan molecules that tether cellulose microfibrils. The activity of XET per unit fresh weight in the apical 10 mm (encompassing the elongation zone) was constant at high [psi]w but increased by more than 2-fold at a [psi]w of -1.6 MPa. Treatment with fluridone to decrease ABA accumulation greatly delayed the increase in activity at low [psi]w. This effect was largely overcome when internal ABA levels were restored by exogenous application. Spatial distribution studies showed that XET activity was increased in the apical 6 mm at low [psi]w whether expressed per unit fresh weight, total soluble protein, or cell wall dry weight, corresponding to the region of continued elongation. Treatment with fluridone progressively inhibited the increase in activity with distance from the apex, correlating with the pattern of inhibition of elongation. Added ABA partly restored activity at all positions. The increase in XET activity at low [psi]w was due to maintenance of the rate of deposition of activity despite decreased deposition of wall material. The loss of activity associated with decreased ABA was due to inhibition of the deposition of activity. The results demonstrate that increased XET activity is associated with maintenance of root elongation at low [psi]w and that this response requires increased ABA. PMID:12232354

  1. 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

  2. ASCORBATE PEROXIDASE6 protects Arabidopsis desiccating and germinating seeds from stress and mediates cross talk between reactive oxygen species, abscisic acid, and auxin.

    PubMed

    Chen, Changming; Letnik, Ilya; Hacham, Yael; Dobrev, Petre; Ben-Daniel, Bat-Hen; Vanková, Radomíra; Amir, Rachel; Miller, Gad

    2014-09-01

    A seed's ability to properly germinate largely depends on its oxidative poise. The level of reactive oxygen species (ROS) in Arabidopsis (Arabidopsis thaliana) is controlled by a large gene network, which includes the gene coding for the hydrogen peroxide-scavenging enzyme, cytosolic ASCORBATE PEROXIDASE6 (APX6), yet its specific function has remained unknown. In this study, we show that seeds lacking APX6 accumulate higher levels of ROS, exhibit increased oxidative damage, and display reduced germination on soil under control conditions and that these effects are further exacerbated under osmotic, salt, or heat stress. In addition, ripening APX6-deficient seeds exposed to heat stress displayed reduced germination vigor. This, together with the increased abundance of APX6 during late stages of maturation, indicates that APX6 activity is critical for the maturation-drying phase. Metabolic profiling revealed an altered activity of the tricarboxylic acid cycle, changes in amino acid levels, and elevated metabolism of abscisic acid (ABA) and auxin in drying apx6 mutant seeds. Further germination assays showed an impaired response of the apx6 mutants to ABA and to indole-3-acetic acid. Relative suppression of abscisic acid insensitive3 (ABI3) and ABI5 expression, two of the major ABA signaling downstream components controlling dormancy, suggested that an alternative signaling route inhibiting germination was activated. Thus, our study uncovered a new role for APX6, in protecting mature desiccating and germinating seeds from excessive oxidative damage, and suggested that APX6 modulate the ROS signal cross talk with hormone signals to properly execute the germination program in Arabidopsis. PMID:25049361

  3. ASCORBATE PEROXIDASE6 Protects Arabidopsis Desiccating and Germinating Seeds from Stress and Mediates Cross Talk between Reactive Oxygen Species, Abscisic Acid, and Auxin1[C][W][OPEN

    PubMed Central

    Chen, Changming; Letnik, Ilya; Hacham, Yael; Dobrev, Petre; Ben-Daniel, Bat-Hen; Vanková, Radomíra; Amir, Rachel; Miller, Gad

    2014-01-01

    A seed’s ability to properly germinate largely depends on its oxidative poise. The level of reactive oxygen species (ROS) in Arabidopsis (Arabidopsis thaliana) is controlled by a large gene network, which includes the gene coding for the hydrogen peroxide-scavenging enzyme, cytosolic ASCORBATE PEROXIDASE6 (APX6), yet its specific function has remained unknown. In this study, we show that seeds lacking APX6 accumulate higher levels of ROS, exhibit increased oxidative damage, and display reduced germination on soil under control conditions and that these effects are further exacerbated under osmotic, salt, or heat stress. In addition, ripening APX6-deficient seeds exposed to heat stress displayed reduced germination vigor. This, together with the increased abundance of APX6 during late stages of maturation, indicates that APX6 activity is critical for the maturation-drying phase. Metabolic profiling revealed an altered activity of the tricarboxylic acid cycle, changes in amino acid levels, and elevated metabolism of abscisic acid (ABA) and auxin in drying apx6 mutant seeds. Further germination assays showed an impaired response of the apx6 mutants to ABA and to indole-3-acetic acid. Relative suppression of abscisic acid insensitive3 (ABI3) and ABI5 expression, two of the major ABA signaling downstream components controlling dormancy, suggested that an alternative signaling route inhibiting germination was activated. Thus, our study uncovered a new role for APX6, in protecting mature desiccating and germinating seeds from excessive oxidative damage, and suggested that APX6 modulate the ROS signal cross talk with hormone signals to properly execute the germination program in Arabidopsis. PMID:25049361

  4. Arabidopsis seed-specific vacuolar aquaporins are involved in maintaining seed longevity under the control of ABSCISIC ACID INSENSITIVE 3.

    PubMed

    Mao, Zhilei; Sun, Weining

    2015-08-01

    The tonoplast intrinsic proteins TIP3;1 and TIP3;2 are specifically expressed during seed maturation and localized to the seed protein storage vacuole membrane. However, the function and physiological roles of TIP3s are still largely unknown. The seed performance of TIP3 knockdown mutants was analysed using the controlled deterioration test. The tip3;1/tip3;2 double mutant was affected in seed longevity and accumulated high levels of hydrogen peroxide compared with the wild type, suggesting that TIP3s function in seed longevity. The transcription factor ABSCISIC ACID INSENSITIVE 3 (ABI3) is known to be involved in seed desiccation tolerance and seed longevity. TIP3 transcript and protein levels were significantly reduced in abi3-6 mutant seeds. TIP3;1 and TIP3;2 promoters could be activated by ABI3 in the presence of abscisic acid (ABA) in Arabidopsis protoplasts. TIP3 proteins were detected in the protoplasts transiently expressing ABI3 and in ABI3-overexpressing seedlings when treated with ABA. Furthermore, ABI3 directly binds to the RY motif of the TIP3 promoters. Therefore, seed-specific TIP3s may help maintain seed longevity under the expressional control of ABI3 during seed maturation and are members of the ABI3-mediated seed longevity pathway together with small heat shock proteins and late embryo abundant proteins. PMID:26019256

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

    PubMed

    Nolan, Kim E; Song, Youhong; Liao, Siyang; Saeed, Nasir A; Zhang, Xiyi; Rose, Ray J

    2014-01-01

    Somatic embryogenesis (SE) can be readily induced in leaf explants of the Jemalong 2HA genotype of the model legume Medicago truncatula by auxin and cytokinin, but rarely in wild-type Jemalong. Gibberellic acid (GA), a hormone not included in the medium, appears to act in Arabidopsis as a repressor of the embryonic state such that low ABA (abscisic acid): GA ratios will inhibit SE. It was important to evaluate the GA effect in M. truncatula in order to formulate generic SE mechanisms, given the Arabidopsis information. It was surprising to find that low ABA:GA ratios in M. truncatula acted synergistically to stimulate SE. The unusual synergism between GA and ABA in inducing SE has utility in improving SE for regeneration and transformation in M. truncatula. Expression of genes previously shown to be important in M. truncatula SE was not increased. In investigating genes previously studied in GA investigations of Arabidopsis SE, there was increased expression of GA2ox and decreased expression of PICKLE, a negative regulator of SE in Arabidopsis. We suggest that in M. truncatula there are different ABA:GA ratios required for down-regulating the PICKLE gene, a repressor of the embryonic state. In M. truncatula it is a low ABA:GA ratio while in Arabidopsis it is a high ABA:GA ratio. In different species the expression of key genes is probably related to differences in how the hormone networks optimise their expression. PMID:24937316

  6. Abscisic Acid- and Stress-Induced Highly Proline-Rich Glycoproteins Regulate Root Growth in Rice1[W][OPEN

    PubMed Central

    Tseng, I-Chieh; Hong, Chwan-Yang; Yu, Su-May; Ho, Tuan-Hua David

    2013-01-01

    In the root of rice (Oryza sativa), abscisic acid (ABA) treatment, salinity, or water deficit stress induces the expression of a family of four genes, REPETITIVE PROLINE-RICH PROTEIN (RePRP). These genes encode two subclasses of novel proline-rich glycoproteins with highly repetitive PX1PX2 motifs, RePRP1 and RePRP2. RePRP orthologs exist only in monocotyledonous plants, and their functions are virtually unknown. Rice RePRPs are heavily glycosylated with arabinose and glucose on multiple hydroxyproline residues. They are significantly different from arabinogalactan proteins that have glycan chains composed of arabinose and galactose. Transient and stable expressions of RePRP-green fluorescent protein reveal that a fraction of this protein is localized to the plasma membrane. In rice roots, ABA treatment increases RePRP expression preferentially in the elongation zone. Overexpression of RePRP in transgenic rice reduces root cell elongation in the absence of ABA, similar to the effect of ABA on wild-type roots. Conversely, simultaneous knockdown of the expression of RePRP1 and RePRP2 reduces the root sensitivity to ABA, indicating that RePRP proteins play an essential role in ABA/stress regulation of root growth and development. Moreover, rice RePRPs specifically interact with a polysaccharide, arabinogalactan, in a dosage-dependent manner. It is suggested that RePRP1 and RePRP2 are functionally redundant suppressors of root cell expansion and probably act through interactions with cell wall components near the plasma membrane. PMID:23886623

  7. Ectopic expression of ABSCISIC ACID 2/GLUCOSE INSENSITIVE 1 in Arabidopsis promotes seed dormancy and stress tolerance.

    PubMed

    Lin, Pei-Chi; Hwang, San-Gwang; Endo, Akira; Okamoto, Masanori; Koshiba, Tomokazu; Cheng, Wan-Hsing

    2007-02-01

    Abscisic acid (ABA) is an important phytohormone that plays a critical role in seed development, dormancy, and stress tolerance. 9-cis-Epoxycarotenoid dioxygenase is the key enzyme controlling ABA biosynthesis and stress tolerance. In this study, we investigated the effect of ectopic expression of another ABA biosynthesis gene, ABA2 (or GLUCOSE INSENSITIVE 1 [GIN1]) encoding a short-chain dehydrogenase/reductase in Arabidopsis (Arabidopsis thaliana). We show that ABA2-overexpressing transgenic plants with elevated ABA levels exhibited seed germination delay and more tolerance to salinity than wild type when grown on agar plates and/or in soil. However, the germination delay was abolished in transgenic plants showing ABA levels over 2-fold higher than that of wild type grown on 250 mm NaCl. The data suggest that there are distinct mechanisms underlying ABA-mediated inhibition of seed germination under diverse stress. The ABA-deficient mutant aba2, with a shorter primary root, can be restored to normal root growth by exogenous application of ABA, whereas transgenic plants overexpressing ABA2 showed normal root growth. The data reflect that the basal levels of ABA are essential for maintaining normal primary root elongation. Furthermore, analysis of ABA2 promoter activity with ABA2::beta-glucuronidase transgenic plants revealed that the promoter activity was enhanced by multiple prolonged stresses, such as drought, salinity, cold, and flooding, but not by short-term stress treatments. Coincidently, prolonged drought stress treatment led to the up-regulation of ABA biosynthetic and sugar-related genes. Thus, the data support ABA2 as a late expression gene that might have a fine-tuning function in mediating ABA biosynthesis through primary metabolic changes in response to stress. PMID:17189333

  8. Gibberellin-to-abscisic acid balances govern development and differentiation of the nucellar projection of barley grains

    PubMed Central

    Weier, Diana; Thiel, Johannes; Kohl, Stefan; Tarkowská, Danuše; Strnad, Miroslav; Schaarschmidt, Sara; Weschke, Winfriede; Weber, Hans; Hause, Bettina

    2014-01-01

    In cereal grains, the maternal nucellar projection (NP) constitutes the link to the filial organs, forming a transfer path for assimilates and signals towards the endosperm. At transition to the storage phase, the NP of barley (Hordeum vulgare) undergoes dynamic and regulated differentiation forming a characteristic pattern of proliferating, elongating, and disintegrating cells. Immunolocalization revealed that abscisic acid (ABA) is abundant in early non-elongated but not in differentiated NP cells. In the maternally affected shrunken-endosperm mutant seg8, NP cells did not elongate and ABA remained abundant. The amounts of the bioactive forms of gibberellins (GAs) as well as their biosynthetic precursors were strongly and transiently increased in wild-type caryopses during the transition and early storage phases. In seg8, this increase was delayed and less pronounced together with deregulated gene expression of specific ABA and GA biosynthetic genes. We concluded that differentiation of the barley NP is driven by a distinct and specific shift from lower to higher GA:ABA ratios and that the spatial–temporal change of GA:ABA balances is required to form the differentiation gradient, which is a prerequisite for ordered transfer processes through the NP. Deregulated ABA:GA balances in seg8 impair the differentiation of the NP and potentially compromise transfer of signals and assimilates, resulting in aberrant endosperm growth. These results highlight the impact of hormonal balances on the proper release of assimilates from maternal to filial organs and provide new insights into maternal effects on endosperm differentiation and growth of barley grains. PMID:25024168

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

    PubMed

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

    2015-09-23

    Fusarium fujikuroi, the causal agent of bakanae disease, is the main seedborne pathogen on rice. To understand the basis of rice resistance, a quantitative method to simultaneously detect phytohormones and phytoalexins was developed by using HPLC-MS/MS. With this method dynamic profiles and possible interactions of defense-related phytohormones and phytoalexins were investigated on two rice cultivars, inoculated or not with F. fujikuroi. In the resistant cultivar Selenio, the presence of pathogen induced high production of phytoalexins, mainly sakuranetin, and symptoms of bakanae were not observed. On the contrary, in the susceptible genotype Dorella, the pathogen induced the production of gibberellin and abscisic acid and inhibited jasmonic acid production, phytoalexins were very low, and bakanae symptoms were observed. The results suggested that a wide range of secondary metabolites are involved in plant defense against pathogens and phytoalexin synthesis could be an important factor for rice resistance against bakanae disease. PMID:26323788

  10. Arabidopsis INCURVATA2 Regulates Salicylic Acid and Abscisic Acid Signaling, and Oxidative Stress Responses.

    PubMed

    Micol-Ponce, Rosa; Sánchez-García, Ana Belén; Xu, Qian; Barrero, José María; Micol, José Luis; Ponce, María Rosa

    2015-11-01

    Epigenetic regulatory states can persist through mitosis and meiosis, but the connection between chromatin structure and DNA replication remains unclear. Arabidopsis INCURVATA2 (ICU2) encodes the catalytic subunit of DNA polymerase α, and null alleles of ICU2 have an embryo-lethal phenotype. Analysis of icu2-1, a hypomorphic allele of ICU2, demonstrated that ICU2 functions in chromatin-mediated cellular memory; icu2-1 strongly impairs ICU2 function in the maintenance of repressive epigenetic marks but does not seem to affect ICU2 polymerase activity. To better understand the global function of ICU2 in epigenetic regulation, here we performed a microarray analysis of icu2-1 mutant plants. We found that the genes up-regulated in the icu2-1 mutant included genes encoding transcription factors and targets of the Polycomb Repressive Complexes. The down-regulated genes included many known players in salicylic acid (SA) biosynthesis and accumulation, ABA signaling and ABA-mediated responses. In addition, we found that icu2-1 plants had reduced SA levels in normal conditions; infection by Fusarium oxysporum induced SA accumulation in the En-2 wild type but not in the icu2-1 mutant. The icu2-1 plants were also hypersensitive to salt stress and exogenous ABA in seedling establishment, post-germination growth and stomatal closure, and accumulated more ABA than the wild type in response to salt stress. The icu2-1 mutant also showed high tolerance to the oxidative stress produced by 3-amino-1,2,4-triazole (3-AT). Our results uncover a role for ICU2 in the regulation of genes involved in ABA signaling as well as in SA biosynthesis and accumulation. PMID:26423959

  11. Solanum lycopersicum IAA15 functions in the 2,4-dichlorophenoxyacetic acid herbicide mechanism of action by mediating abscisic acid signalling.

    PubMed

    Xu, Tao; Wang, Yanling; Liu, Xin; Gao, Song; Qi, Mingfang; Li, Tianlai

    2015-07-01

    2,4-Dichlorophenoxyacetic acid (2,4-D), an important plant growth regulator, is the herbicide most commonly used worldwide to control weeds. However, broad-leaf fruits and vegetables are extremely sensitive to herbicides, which can cause damage and result in lost crops when applied in a manner inconsistent with the directions. Despite detailed knowledge of the mechanism of 2,4-D, the regulation of auxin signalling is still unclear. For example, although the major mediators of auxin signalling, including auxin/indole acetic acid (AUX/IAA) proteins and auxin response factors (ARFs), are known to mediate auxinic herbicides, the underlying mechanisms are still unclear. In this study, the effects of 2,4-D on AUX/IAA gene expression in tomato were investigated, and the two most notably up-regulated genes, SlIAA15 and SlIAA29, were selected for further study. Western blotting revealed the substantial accumulation of both SlIAA15 and SlIAA29, and the expression levels of the corresponding genes were increased following abscisic acid (ABA) and ethylene treatment. Overexpressing SlIAA15, but not SlIAA29, induced a 2,4-D herbicide damage phenotype. The 35S::SlIAA15 line exhibited a strong reduction in leaf stomatal density and altered expression of some R2R3 MYB genes that are putatively involved in the regulation of stomatal differentiation. Further study revealed that root elongation in 35S::SlIAA15 was sensitive to ABA treatment, and was most probably due to the altered expression of an ABA signal transduction gene. In addition, the altered auxin sensitivities of SlIAA15 transformants were also explored. These results suggested that SlIAA15 plays an important role in determining the effects of the herbicide 2,4-D. PMID:25948703

  12. The qSD12 Underlying Gene Promotes Abscisic Acid Accumulation in Early Developing Seeds to Induce Primary Dormancy in Rice

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Seeds acquire primary dormancy during their development and the phytohormone abscisic acid (ABA) is considered to play a role in inducing the dormancy. qSD12 is a major seed dormancy QTL identified from weedy rice. This research was conducted to identify qSD12 candidate genes, isolate the candidat...

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

    PubMed Central

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

    2016-01-01

    Along with sugar accumulation and colour development, softening is an important physiological change during the onset of ripening in fruits. In this work, we investigated the relationships among major events during softening in grape (Vitis vinifera L.) by quantifying elasticity in individual berries. In addition, we delayed softening and inhibited sugar accumulation using a mechanical growth-preventing treatment in order to identify processes that are sugar and/or growth dependent. Ripening processes commenced on various days after anthesis, but always at similarly low elasticity and turgor. Much of the softening occurred in the absence of other changes in berry physiology investigated here. Several genes encoding key cell wall-modifying enzymes were not up-regulated until softening was largely completed, suggesting softening may result primarily from decreases in turgor. Similarly, there was no decrease in solute potential, increase in sugar concentration, or colour development until elasticity and turgor were near minimum values, and these processes were inhibited when berry growth was prevented. Increases in abscisic acid occurred early during softening and in the absence of significant expression of the V. vinifera 9-cis-epoxycarotenoid dioxygenases. However, these increases were coincident with decreases in the abscisic acid catabolite diphasic acid, indicating that initial increases in abscisic acid may result from decreases in catabolism and/or exogenous import. These data suggest that softening, decreases in turgor, and increases in abscisic acid represent some of the earliest events during the onset of ripening. Later, physical growth, further increases in abscisic acid, and the accumulation of sugar are integral for colour development. PMID:26590311

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

    PubMed

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

    2016-02-01

    Along with sugar accumulation and colour development, softening is an important physiological change during the onset of ripening in fruits. In this work, we investigated the relationships among major events during softening in grape (Vitis vinifera L.) by quantifying elasticity in individual berries. In addition, we delayed softening and inhibited sugar accumulation using a mechanical growth-preventing treatment in order to identify processes that are sugar and/or growth dependent. Ripening processes commenced on various days after anthesis, but always at similarly low elasticity and turgor. Much of the softening occurred in the absence of other changes in berry physiology investigated here. Several genes encoding key cell wall-modifying enzymes were not up-regulated until softening was largely completed, suggesting softening may result primarily from decreases in turgor. Similarly, there was no decrease in solute potential, increase in sugar concentration, or colour development until elasticity and turgor were near minimum values, and these processes were inhibited when berry growth was prevented. Increases in abscisic acid occurred early during softening and in the absence of significant expression of the V. vinifera 9-cis-epoxycarotenoid dioxygenases. However, these increases were coincident with decreases in the abscisic acid catabolite diphasic acid, indicating that initial increases in abscisic acid may result from decreases in catabolism and/or exogenous import. These data suggest that softening, decreases in turgor, and increases in abscisic acid represent some of the earliest events during the onset of ripening. Later, physical growth, further increases in abscisic acid, and the accumulation of sugar are integral for colour development. PMID:26590311

  15. Gibberellic Acid-Stimulated Arabidopsis6 Serves as an Integrator of Gibberellin, Abscisic Acid, and Glucose Signaling during Seed Germination in Arabidopsis1[OPEN

    PubMed Central

    Zhong, Chunmei; Xu, Hao; Ye, Siting; Wang, Shiyi; Li, Lingfei; Zhang, Shengchun; Wang, Xiaojing

    2015-01-01

    The DELLA protein REPRESSOR OF ga1-3-LIKE2 (RGL2) plays an important role in seed germination under different conditions through a number of transcription factors. However, the functions of the structural genes associated with RGL2-regulated germination are less defined. Here, we report the role of an Arabidopsis (Arabidopsis thaliana) cell wall-localized protein, Gibberellic Acid-Stimulated Arabidopsis6 (AtGASA6), in functionally linking RGL2 and a cell wall loosening expansin protein (Arabidopsis expansin A1 [AtEXPA1]), resulting in the control of embryonic axis elongation and seed germination. AtGASA6-overexpressing seeds showed precocious germination, whereas transfer DNA and RNA interference mutant seeds displayed delayed seed germination under abscisic acid, paclobutrazol, and glucose (Glc) stress conditions. The differences in germination rates resulted from corresponding variation in cell elongation in the hypocotyl-radicle transition region of the embryonic axis. AtGASA6 was down-regulated by RGL2, GLUCOSE INSENSITIVE2, and ABSCISIC ACID-INSENSITIVE5 genes, and loss of AtGASA6 expression in the gasa6 mutant reversed the insensitivity shown by the rgl2 mutant to paclobutrazol and the gin2 mutant to Glc-induced stress, suggesting that it is involved in regulating both the gibberellin and Glc signaling pathways. Furthermore, it was found that the promotion of seed germination and length of embryonic axis by AtGASA6 resulted from a promotion of cell elongation at the embryonic axis mediated by AtEXPA1. Taken together, the data indicate that AtGASA6 links RGL2 and AtEXPA1 functions and plays a role as an integrator of gibberellin, abscisic acid, and Glc signaling, resulting in the regulation of seed germination through a promotion of cell elongation. PMID:26400990

  16. An Abscisic Acid-Activated and Calcium-Independent Protein Kinase from Guard Cells of Fava Bean.

    PubMed Central

    Li, J.; Assmann, S. M.

    1996-01-01

    Abscisic acid (ABA) regulation of stomatal aperture is known to involve both Ca2+-dependent and Ca2+-independent signal transduction pathways. Electrophysiological studies suggest that protein phosphorylation is involved in ABA action in guard cells. Using biochemical approaches, we identified an ABA-activated and Ca2+- independent protein kinase (AAPK) from guard cell protoplasts of fava bean. Autophosphorylation of AAPK was rapidly (~1 min) activated by ABA in a Ca2+- independent manner. ABA-activated autophosphorylation of AAPK occurred on serine but not on tyrosine residues and appeared to be guard cell specific. AAPK phosphorylated histone type III-S on serine and threonine residues, and its activity toward histone type III-S was markedly stimulated in ABA-treated guard cell protoplasts. Our results suggest that AAPK may play an important role in the Ca2+-independent ABA signaling pathways of guard cells. PMID:12239380

  17. Transcriptional Regulation of Tetrapyrrole Biosynthetic Genes Explains Abscisic Acid-Induced Heme Accumulation in the Unicellular Red Alga Cyanidioschyzon merolae

    PubMed Central

    Kobayashi, Yuki; Tanaka, Kan

    2016-01-01

    Abscisic acid (ABA), a pivotal phytohormone that is synthesized in response to abiotic stresses and other environmental changes, induces various physiological responses. Heme, in its unbound form, has a positive signaling role in cell-cycle initiation in Cyanidioschyzon merolae. ABA induces heme accumulation, but also prevents cell-cycle initiation through the titration of the unbound heme by inducing the heme scavenging protein tryptophan-rich sensory protein-related protein O. In this study, we analyzed the accumulation of tetrapyrrole biosynthetic gene transcripts after the addition of ABA to the medium and found that transcripts of a ferrochelatase and a magnesium-chelatase subunit increased, while other examined transcripts decreased. Under the same conditions, the heme and magnesium-protoporphyrin IX contents increased, while the protoporphyrin IX content decreased. Thus, ABA may regulate the intracellular heme and other tetrapyrrole contents through the transcriptional regulation of biosynthetic genes. PMID:27621743

  18. 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. PMID:22131163

  19. An Abscisic Acid-Activated and Calcium-Independent Protein Kinase from Guard Cells of Fava Bean.

    PubMed

    Li, J.; Assmann, S. M.

    1996-12-01

    Abscisic acid (ABA) regulation of stomatal aperture is known to involve both Ca2+-dependent and Ca2+-independent signal transduction pathways. Electrophysiological studies suggest that protein phosphorylation is involved in ABA action in guard cells. Using biochemical approaches, we identified an ABA-activated and Ca2+- independent protein kinase (AAPK) from guard cell protoplasts of fava bean. Autophosphorylation of AAPK was rapidly (~1 min) activated by ABA in a Ca2+- independent manner. ABA-activated autophosphorylation of AAPK occurred on serine but not on tyrosine residues and appeared to be guard cell specific. AAPK phosphorylated histone type III-S on serine and threonine residues, and its activity toward histone type III-S was markedly stimulated in ABA-treated guard cell protoplasts. Our results suggest that AAPK may play an important role in the Ca2+-independent ABA signaling pathways of guard cells. PMID:12239380

  20. Transcriptional Regulation of Tetrapyrrole Biosynthetic Genes Explains Abscisic Acid-Induced Heme Accumulation in the Unicellular Red Alga Cyanidioschyzon merolae.

    PubMed

    Kobayashi, Yuki; Tanaka, Kan

    2016-01-01

    Abscisic acid (ABA), a pivotal phytohormone that is synthesized in response to abiotic stresses and other environmental changes, induces various physiological responses. Heme, in its unbound form, has a positive signaling role in cell-cycle initiation in Cyanidioschyzon merolae. ABA induces heme accumulation, but also prevents cell-cycle initiation through the titration of the unbound heme by inducing the heme scavenging protein tryptophan-rich sensory protein-related protein O. In this study, we analyzed the accumulation of tetrapyrrole biosynthetic gene transcripts after the addition of ABA to the medium and found that transcripts of a ferrochelatase and a magnesium-chelatase subunit increased, while other examined transcripts decreased. Under the same conditions, the heme and magnesium-protoporphyrin IX contents increased, while the protoporphyrin IX content decreased. Thus, ABA may regulate the intracellular heme and other tetrapyrrole contents through the transcriptional regulation of biosynthetic genes. PMID:27621743

  1. Ultrastructural and cytochemical aspects of induced apogamy following abscisic acid pre-treatment of secondary moss protonema.

    PubMed

    Menon, M K; Bell, P R

    1981-05-01

    Abscisic acid (ABA) treatment of secondary protonema of Physcomitrium pyriforme Brid in the presence of sucrose does not prevent cell division but results in shorter cells with vesicular cytoplasm and an accumulation of lipid. When transferred to sucrose medium without ABA and with low irradiance isodiametric intercalary cells are cut off which give rise to apogamous sporophytes either directly or after the formation of a small amount of callus. The organization of the cells leading up to the apogamous sporophyte is described. The cells initiating the sporophyte develop dense cytoplasm and the walls become labyrinthine and callosed, but they do not form any recognizable placenta. It is proposed that labyrinthine walls are a consequence of a perturbation of cell wall metabolism as growth changes from gametophytic to sporophytic. The use of the term "transfer cell" for this kind of cell is questioned and the need for a causal approach to the investigation of labyrinthine walls is stressed. PMID:24302107

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

    SciTech Connect

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

    2011-09-06

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

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

    SciTech Connect

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

    2010-01-01

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

  4. Regulation of Phosphoenolpyruvate Carboxylase Phosphorylation by Metabolites and Abscisic Acid during the Development and Germination of Barley Seeds1[C][W

    PubMed Central

    Feria, Ana-Belén; Alvarez, Rosario; Cochereau, Ludivine; Vidal, Jean; García-Mauriño, Sofía; Echevarría, Cristina

    2008-01-01

    During barley (Hordeum vulgare) seed development, phosphoenolpyruvate carboxylase (PEPC) activity increased and PEPC-specific antibodies revealed housekeeping (103-kD) and inducible (108-kD) subunits. Bacterial-type PEPC fragments were immunologically detected in denatured protein extracts from dry and imbibed conditions; however, on nondenaturing gels, the activity of the recently reported octameric PEPC (in castor [Ricinus communis] oil seeds) was not detected. The phosphorylation state of the PEPC, as judged by l-malate 50% inhibition of initial activity values, phosphoprotein chromatography, and immunodetection of the phosphorylated N terminus, was found to be high between 8 and 18 d postanthesis (DPA) and during imbibition. In contrast, the enzyme appeared to be in a low phosphorylation state from 20 DPA up to dry seed. The time course of 32/36-kD, Ca2+-independent PEPC kinase activity exhibited a substantial increase after 30 DPA that did not coincide with the PEPC phosphorylation profile. This kinase was found to be inhibited by l-malate and not by putative protein inhibitors, and the PEPC phosphorylation status correlated with high glucose-6-phosphate to malate ratios, thereby suggesting an in vivo metabolic control of the kinase. PEPC phosphorylation was also regulated by photosynthate supply at 11 DPA. In addition, when fed exogenously to imbibing seeds, abscisic acid significantly increased PEPC kinase activity. This was further enhanced by the cytosolic protein synthesis inhibitor cycloheximide but blocked by protease inhibitors, thereby suggesting that the phytohormone acts on the stability of the kinase. We propose that a similar abscisic acid-dependent effect may contribute to produce the increase in PEPC kinase activity during desiccation stages. PMID:18753284

  5. Cell-Wall Changes and Cell Tension in Response to Cold Acclimation and Exogenous Abscisic Acid in Leaves and Cell Cultures.

    PubMed Central

    Rajashekar, C. B.; Lafta, A.

    1996-01-01

    Freeze-induced cell tensions were determined by cell water relations in leaves of broadleaf evergreen species and cell cultures of grapes (Vitis spp.) and apple (Malus domestica). Cell tensions increased in response to cold acclimation in leaves of broadleaf evergreen species during extracellular freezing, indicating a higher resistance to cell volume changes during freezing in cold-hardened leaves than in unhardened leaves. Unhardened leaves, typically, did not develop tension greater than 3.67 MPa, whereas cold-hardened leaves attained tensions up to 12 MPa. With further freezing there was a rapid decline and a loss of tension in unhardened leaves of all the broadleaf evergreen species studied. Also, similar results were observed in cold-hardened leaves of all of the species except in those of inkberry (Ilex glabra) and Euonymus fortunei, in which negative pressures persisted below -40[deg]C. Abscisic acid treatment of inkberry and Euonymus kiautschovica resulted in increases in freeze-induced tensions in leaves, suggesting that both cold acclimation and abscisic acid have similar effects on freezing behavior[mdash] specifically on the ability of cell walls to undergo deformation. Decreases in peak tensions were generally associated with lethal freezing injury and may suggest cavitation of cellular water. However, in suspension-cultured cells of grapes and apple, no cell tension was observed during freezing. Cold acclimation of these cells resulted in an increase in the cell-wall strength and a decrease in the limiting cell-wall pore size from 35 to 22 A in grape cells and from 29 to 22 A in apple cells. PMID:12226314

  6. Modular nature of abscisic acid (ABA) response complexes: composite promoter units that are necessary and sufficient for ABA induction of gene expression in barley.

    PubMed Central

    Shen, Q; Zhang, P; Ho, T H

    1996-01-01

    The modular nature of the abscisic acid response complex (ABRC), the promoter unit necessary and sufficient for abscisic acid (ABA) induction of gene expression in barley, is defined in this study. We investigated ABA induction of a barley late embrogenesis abundant (Lea) gene, HVA1, and found that the ABRC of this gene consists of a 10-bp box with an ACGT core (ACGT-box) and the 11 bp directly upstream, named coupling element 3 (CE3). Only one copy of this ABRC is sufficient to confer ABA induction when linked to a minimal promoter. Because we previously reported another ABRC in the barley HVA22 gene, which consists of an ACGT-box with a distal coupling element (CE1), exchange experiments were conducted to study the interaction among modular elements in these ABRCs. We show that ACGT-boxes in these ABRCs are interchangeable, indicating that an ACGT-box can interact with either a distal or a proximal coupling element to confer ABA response. However, the two coupling elements are not fully exchangeable. Although CE3 can function either proximal or distal to the ACGT-box, CE1 is only functional at the distal position. The presence of both the distal and the proximal coupling elements has a synergistic effect on the absolute level of expression as well as on ABA induction. These ABRCs function in both seed and vegetative tissues. In seeds, ABA induction of the ABRC containing the proximal CE3, but not the ABRC with the distal CE1, is enhanced in the presence of the transcription regulator Viviparous1, indicating that these two ABRCs are mediated by different ABA signal transduction pathways. PMID:8768371

  7. Abscisic Acid Promotes Susceptibility to the Rice Leaf Blight Pathogen Xanthomonas oryzae pv oryzae by Suppressing Salicylic Acid-Mediated Defenses

    PubMed Central

    Xu, Jing; Audenaert, Kris

    2013-01-01

    The plant hormone abscisic acid (ABA) is involved in a wide variety of plant processes, including the initiation of stress-adaptive responses to various environmental cues. Recently, ABA also emerged as a central factor in the regulation and integration of plant immune responses, although little is known about the underlying mechanisms. Aiming to advance our understanding of ABA-modulated disease resistance, we have analyzed the impact, dynamics and interrelationship of ABA and the classic defense hormone salicylic acid (SA) during progression of rice infection by the leaf blight pathogen Xanthomonas oryzae pv. oryzae (Xoo). Consistent with ABA negatively regulating resistance to Xoo, we found that exogenously administered ABA renders rice hypersusceptible to infection, whereas chemical and genetic disruption of ABA biosynthesis and signaling, respectively, led to enhanced Xoo resistance. In addition, we found successful Xoo infection to be associated with extensive reprogramming of ABA biosynthesis and response genes, suggesting that ABA functions as a virulence factor for Xoo. Interestingly, several lines of evidence indicate that this immune-suppressive effect of ABA is due at least in part to suppression of SA-mediated defenses that normally serve to limit pathogen growth. Resistance induced by the ABA biosynthesis inhibitor fluridone, however, appears to operate in a SA-independent manner and is likely due to induction of non-specific physiological stress. Collectively, our findings favor a scenario whereby virulent Xoo hijacks the rice ABA machinery to cause disease and highlight the importance of ABA and its crosstalk with SA in shaping the outcome of rice-Xoo interactions. PMID:23826294

  8. Kinetic Characterisation of a Single Chain Antibody against the Hormone Abscisic Acid: Comparison with Its Parental Monoclonal

    PubMed Central

    Badescu, George O.; Marsh, Andrew; Smith, Timothy R.; Thompson, Andrew J.; Napier, Richard M.

    2016-01-01

    A single-chain Fv fragment antibody (scFv) specific for the plant hormone abscisic acid (ABA) has been expressed in the bacterium Escherichia coli as a fusion protein. The kinetics of ABA binding have been measured using surface plasmon resonance spectrometry (BIAcore 2000) using surface and solution assays. Care was taken to calculate the concentration of active protein in each sample using initial rate measurements under conditions of partial mass transport limitation. The fusion product, parental monoclonal antibody and the free scFv all have low nanomolar affinity constants, but there is a lower dissociation rate constant for the parental monoclonal resulting in a three-fold greater affinity. Analogue specificity was tested and structure-activity binding preferences measured. The biologically-active (+)-ABA enantiomer is recognised with an affinity three orders of magnitude higher than the inactive (-)-ABA. Metabolites of ABA including phaseic acid, dihydrophaseic acid and deoxy-ABA have affinities over 100-fold lower than that for (+)-ABA. These properties of the scFv make it suitable as a sensor domain in bioreporters specific for the naturally occurring form of ABA. PMID:27023768

  9. The Wheat Abscisic Acid-Responsive Protein Kinase mRNA, PKABA1, Is Up-Regulated by Dehydration, Cold Temperature, and Osmotic Stress.

    PubMed Central

    Holappa, L. D.; Walker-Simmons, M. K.

    1995-01-01

    The effects of dehydration, cold-temperature treatment, and osmotic and salt stress on the expression of an abscisic acid-responsive protein kinase mRNA (PKABA1) were determined in wheat (Triticum aestivum L.) seedlings. The PKABA1 transcript was detectable at basal levels in tissues of nonstressed plants and accumulated to higher levels in shoot, scutellar, and root tissues of stressed plants. PKABA1 transcript accumulated rapidly within 2 h following dehydration and within 24 h following other treatments (cold, osmotic stress, and high salt). The accumulation of PKABA1 mRNA could not be separated temporally from that of a wheat group 3 late embryogenesis abundant mRNA during dehydration and cold treatment. High PKABA1 mRNA levels were observed in field-grown plants growing under cold winter conditions but not under warmer summer conditions. A recent GenBank data base search indicated that other plant protein kinases with similar acidic amino acid stretches as in PKABA1 have been identified, and some of these kinases are responsive to environmental signals. These results suggest that PKABA1 may be part of general environmental stress responses in wheat. PMID:12228537

  10. Exogenous abscisic acid alleviates zinc uptake and accumulation in Populus × canescens exposed to excess zinc.

    PubMed

    Shi, Wen-Guang; Li, Hong; Liu, Tong-Xian; Polle, Andrea; Peng, Chang-Hui; Luo, Zhi-Bin

    2015-01-01

    A greenhouse experiment was conducted to study whether exogenous abscisic acid (ABA) mediates the responses of poplars to excess zinc (Zn). Populus × canescens seedlings were treated with either basal or excess Zn levels and either 0 or 10 μm ABA. Excess Zn led to reduced photosynthetic rates, increased Zn accumulation, induced foliar ABA and salicylic acid (SA), decreased foliar gibberellin (GA3 ) and auxin (IAA), elevated root H2 O2 levels, and increased root ratios of glutathione (GSH) to GSSG and foliar ratios of ascorbate (ASC) to dehydroascorbate (DHA) in poplars. While exogenous ABA decreased foliar Zn concentrations with 7 d treatments, it increased levels of endogenous ABA, GA3 and SA in roots, and resulted in highly increased foliar ASC accumulation and ratios of ASC to DHA. The transcript levels of several genes involved in Zn uptake and detoxification, such as yellow stripe-like family protein 2 (YSL2) and plant cadmium resistance protein 2 (PCR2), were enhanced in poplar roots by excess Zn but repressed by exogenous ABA application. These results suggest that exogenous ABA can decrease Zn concentrations in P. × canescens under excess Zn for 7 d, likely by modulating the transcript levels of key genes involved in Zn uptake and detoxification. PMID:25158610