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Ng LM, Melcher K, Teh BT, Xu HE. Abscisic acid perception and signaling: structural mechanisms and applications. Acta Pharmacol Sin 2014; 35:567-84. [PMID: 24786231 DOI: 10.1038/aps.2014.5] [Citation(s) in RCA: 85] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2013] [Accepted: 01/16/2013] [Indexed: 01/13/2023] Open
Abstract
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.
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Hayashi Y, Takahashi K, Inoue SI, Kinoshita T. Abscisic acid suppresses hypocotyl elongation by dephosphorylating plasma membrane H(+)-ATPase in Arabidopsis thaliana. PLANT & CELL PHYSIOLOGY 2014; 55:845-53. [PMID: 24492258 DOI: 10.1093/pcp/pcu028] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Plasma membrane H(+)-ATPase is thought to mediate hypocotyl elongation, which is induced by the phytohormone auxin through the phosphorylation of the penultimate threonine of H(+)-ATPase. However, regulation of the H(+)-ATPase during hypocotyl elongation by other signals has not been elucidated. Hypocotyl elongation in etiolated seedlings of Arabidopsis thaliana was suppressed by the H(+)-ATPase inhibitors vanadate and erythrosine B, and was significantly reduced in aha2-5, which is a knockout mutant of the major H(+)-ATPase isoform in etiolated seedlings. Application of the phytohormone ABA to etiolated seedlings suppressed hypocotyl elongation within 30 min at the half-inhibitory concentration (4.2 µM), and induced dephosphorylation of the penultimate threonine of H(+)-ATPase without affecting the amount of H(+)-ATPase. Interestingly, an ABA-insensitive mutant, abi1-1, did not show ABA inhibition of hypocotyl elongation or ABA-induced dephosphorylation of H(+)-ATPase. This indicates that ABI1, which is an early ABA signaling component through the ABA receptor PYR/PYL/RCARs (pyrabactin resistance/pyrabactin resistance 1-like/regulatory component of ABA receptor), is involved in these responses. In addition, we found that the fungal toxin fusiccocin (FC), an H(+)-ATPase activator, induced hypocotyl elongation and phosphorylation of the penultimate threonine of H(+)-ATPase, and that FC-induced hypocotyl elongation and phosphorylation of H(+)-ATPase were significantly suppressed by ABA. Taken together, these results indicate that ABA has an antagonistic effect on hypocotyl elongation through, at least in part, dephosphorylation of H(+)-ATPase in etiolated seedlings.
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Affiliation(s)
- Yuki Hayashi
- Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa, Nagoya, 464-8602 Japan
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Guan C, Wang X, Feng J, Hong S, Liang Y, Ren B, Zuo J. Cytokinin antagonizes abscisic acid-mediated inhibition of cotyledon greening by promoting the degradation of abscisic acid insensitive5 protein in Arabidopsis. PLANT PHYSIOLOGY 2014; 164:1515-26. [PMID: 24443524 PMCID: PMC3938637 DOI: 10.1104/pp.113.234740] [Citation(s) in RCA: 81] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2013] [Accepted: 01/16/2014] [Indexed: 05/18/2023]
Abstract
In higher plants, seed germination is followed by postgerminative growth. One of the key developmental events during postgerminative growth is cotyledon greening, which enables a seedling to establish photosynthetic capacity. The plant phytohormone abscisic acid (ABA) plays a vital role by inhibiting seed germination and postgerminative growth in response to dynamically changing internal and environmental cues. It has been shown that abscisic acid insensitive5 (ABI5), a basic leucine zipper transcription factor, is an important factor in the regulation of the ABA-mediated inhibitory effect on seed germination and postgerminative growth. Conversely, the phytohormone cytokinin has been proposed to promote seed germination by antagonizing the ABA-mediated inhibitory effect. However, the underpinning molecular mechanism of cytokinin-repressed ABA signaling is largely unknown. Here, we show that cytokinin specifically antagonizes ABA-mediated inhibition of cotyledon greening with minimal effects on seed germination in Arabidopsis (Arabidopsis thaliana). We found that the cytokinin-antagonized ABA effect is dependent on a functional cytokinin signaling pathway, mainly involved in the cytokinin receptor gene cytokinin response1/Arabidopsis histidine kinase4, downstream histidine phosphotransfer protein genes AHP2, AHP3, and AHP5, and a type B response regulator gene, ARR12, which genetically acts upstream of ABI5 to regulate cotyledon greening. Cytokinin has no apparent effect on the transcription of ABI5. However, cytokinin efficiently promotes the proteasomal degradation of ABI5 in a cytokinin signaling-dependent manner. These results define a genetic pathway through which cytokinin specifically induces the degradation of ABI5 protein, thereby antagonizing ABA-mediated inhibition of postgerminative growth.
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105
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Group A PP2Cs evolved in land plants as key regulators of intrinsic desiccation tolerance. Nat Commun 2014; 4:2219. [PMID: 23900426 PMCID: PMC3731658 DOI: 10.1038/ncomms3219] [Citation(s) in RCA: 96] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2012] [Accepted: 06/28/2013] [Indexed: 01/26/2023] Open
Abstract
Vegetative desiccation tolerance is common in bryophytes, although this character has been lost in most vascular plants. The moss Physcomitrella patens survives complete desiccation if treated with abscisic acid (ABA). Group A protein phosphatases type 2C (PP2C) are negative regulators of abscisic acid signalling. Here we show that the elimination of Group A PP2C is sufficient to ensure P. patens survival to full desiccation, without ABA treatment, although its growth is severely hindered. Microarray analysis shows that the Group A PP2C-regulated genes exclusively overlap with genes exhibiting a high level of ABA induction. Group A PP2C disruption weakly affects ABA-activated kinase activity, indicating Group A PP2C action downstream of these kinases in the moss. We propose that Group A PP2C emerged in land plants to repress desiccation tolerance mechanisms, possibly facilitating plants propagation on land, whereas ABA releases the intrinsic desiccation tolerance from Group A PP2C regulation.
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Hu R, Zhu Y, Shen G, Zhang H. TAP46 plays a positive role in the ABSCISIC ACID INSENSITIVE5-regulated gene expression in Arabidopsis. PLANT PHYSIOLOGY 2014; 164:721-34. [PMID: 24357600 PMCID: PMC3912101 DOI: 10.1104/pp.113.233684] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2013] [Accepted: 12/17/2013] [Indexed: 05/19/2023]
Abstract
TAP46 is a protein phosphatase2A (PP2A)-associated protein that regulates PP2A activity in Arabidopsis (Arabidopsis thaliana). To study how PP2A is involved in abscisic acid (ABA) signaling in plants, we studied the function of TAP46 in ABA-regulated seed maturation and seedling development. Expression of TAP46 coincides with the action of ABA in developing seeds and during seed germination, and the TAP46 transcript reaches to the highest level in mature seeds. Real-time polymerase chain reaction analysis indicates that external ABA can increase TAP46 transcript level transiently during seed germination. Overexpression of TAP46 increases plant sensitivity to ABA, while tap46 knockdown mutants are less sensitive to ABA during seed germination, suggesting that TAP46 functions positively in ABA signaling. Overexpression of TAP46 also leads to lower PP2A activity, while tap46-1 knockdown mutant displays higher PP2A activity, suggesting that TAP46 negatively regulates PP2A activity in Arabidopsis. Both TAP46 and PP2A interact with the ABA-regulated transcription factor ABA INSENSITIVE5 (ABI5) in vivo, and TAP46's binding to ABI5 can stabilize ABI5. Furthermore, TAP46's binding to the phosphorylated ABI5 may prevent PP2A or PP2A-like protein phosphatases from removing the phosphate from ABI5, thereby maintaining ABI5 in its active form. Overexpression of TAP46 and inhibition of activities of PP2A or PP2A-like protein phosphatases can increase transcript levels of several ABI5-regulated genes, suggesting that TAP46 is a positive factor in the ABA-regulated gene expression in Arabidopsis.
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Abstract
Abscisic acid (ABA) is one of the major phytohormones and regulates various processes in the plant life cycle, for example, seed development and abiotic/biotic stress responses. Recent studies have made significant progress in elucidating ABA signaling and established a simple ABA signaling model consisting of three core components: PYR/PYL/RCAR receptors, 2C-type protein phosphatases, and SnRK2 protein kinases. This model highlights the importance of protein phosphorylation mediated by SnRK2, but the downstream substrates of SnRK2 remain to be determined to complete the model. Previous studies have identified several SnRK2 substrates involving transcription factors and ion channels. Recently, SnRK2 substrates have been further surveyed by a phosphoproteomic approach, giving new insights on the SnRK2 downstream pathway. Other protein kinases, e.g., Ca(2+)-dependent protein kinase (CDPK) and mitogen-activated protein kinase (MAPK), have been identified as ABA signaling factors. Some evidence suggests that the SnRK2 pathway partially interacts with CDPK or MAPK pathways. In this chapter, recent advances in ABA signaling study are summarized, primarily focusing on two major protein kinases, SnRK2 and MAPK. Challenges for further study of the ABA-dependent protein phosphorylation network are also discussed.
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Affiliation(s)
- Taishi Umezawa
- Faculty of Agriculture, Tokyo University of Agriculture and Technology, Tokyo, Japan
| | | | - Kazuo Shinozaki
- RIKEN Center for Sustainable Resource Science, Tsukuba, Japan.
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Bai G, Yang DH, Zhao Y, Ha S, Yang F, Ma J, Gao XS, Wang ZM, Zhu JK. Interactions between soybean ABA receptors and type 2C protein phosphatases. PLANT MOLECULAR BIOLOGY 2013; 83:651-64. [PMID: 23934343 PMCID: PMC3834219 DOI: 10.1007/s11103-013-0114-4] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2013] [Accepted: 07/11/2013] [Indexed: 05/18/2023]
Abstract
The plant hormone abscisic acid (ABA) plays important roles in regulating plant growth, development, and responses to environmental stresses. Proteins in the PYR/PYL/RCAR family (hereafter referred to as PYLs) are known as ABA receptors. Since most studies thus far have focused on Arabidopsis PYLs, little is known about PYL homologs in crop plants. We report here the characterization of 21 PYL homologs (GmPYLs) in soybean. Twenty-three putative GmPYLs can be found from soybean genome sequence and categorized into three subgroups. GmPYLs interact with AtABI1 and two GmPP2Cs in diverse manners. A lot of the subgroup I GmPYLs interact with PP2Cs in an ABA-dependent manner, whereas most of the subgroup II and III GmPYLs bind to PP2Cs in an ABA-independent manner. The subgroup III GmPYL23, which cannot interact with any of the tested PP2Cs, differs from other GmPYLs. The CL2/gate domain is crucial for GmPYLs-PP2Cs interaction, and a mutation in the conserved proline (P109S) abolishes the interaction between GmPYL1 and AtABI1. Furthermore, the ABA dependence of GmPYLs-PP2Cs interactions are partially correlated with two amino acid residues preceding the CL2/gate domain of GmPYLs. We also show that GmPYL1 interacts with AtABI1 in an ABA-dependent manner in plant cells. Three GmPYLs differentially inhibit AtABI1 and GmPP2C1 in an ABA-dependent or -enhanced manner in vitro. In addition, ectopically expressing GmPYL1 partially restores ABA sensitivity of the Arabidopsis triple mutant pyr1/pyl1/pyl4. Taken together, our results suggest that soybean GmPYLs are ABA receptors that function by interacting and inhibiting PP2Cs.
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Affiliation(s)
- Ge Bai
- School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, P. R. China, 200240
- Shanghai Center for Plant Stress Biology, Shanghai Institute of Biological Sciences, Chinese Academy of Sciences, Shanghai, P. R. China, 201602
| | - Da-Hai Yang
- Shanghai Center for Plant Stress Biology, Shanghai Institute of Biological Sciences, Chinese Academy of Sciences, Shanghai, P. R. China, 201602
- Institute of Plant Physiology and Ecology, Shanghai Institute of Biological Sciences, Chinese Academy of Sciences, Shanghai, P. R. China, 200032
| | - Yang Zhao
- Shanghai Center for Plant Stress Biology, Shanghai Institute of Biological Sciences, Chinese Academy of Sciences, Shanghai, P. R. China, 201602
- Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, IN 47907, USA
| | - Si Ha
- Shanghai Center for Plant Stress Biology, Shanghai Institute of Biological Sciences, Chinese Academy of Sciences, Shanghai, P. R. China, 201602
- Institute of Plant Physiology and Ecology, Shanghai Institute of Biological Sciences, Chinese Academy of Sciences, Shanghai, P. R. China, 200032
| | - Fen Yang
- Shanghai Center for Plant Stress Biology, Shanghai Institute of Biological Sciences, Chinese Academy of Sciences, Shanghai, P. R. China, 201602
| | - Jun Ma
- Shanghai Center for Plant Stress Biology, Shanghai Institute of Biological Sciences, Chinese Academy of Sciences, Shanghai, P. R. China, 201602
| | - Xiao-Su Gao
- Institute of Plant Physiology and Ecology, Shanghai Institute of Biological Sciences, Chinese Academy of Sciences, Shanghai, P. R. China, 200032
| | - Zhi-Min Wang
- School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, P. R. China, 200240
| | - Jian-Kang Zhu
- Shanghai Center for Plant Stress Biology, Shanghai Institute of Biological Sciences, Chinese Academy of Sciences, Shanghai, P. R. China, 201602
- Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, IN 47907, USA
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109
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110
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Li J, Besseau S, Törönen P, Sipari N, Kollist H, Holm L, Palva ET. Defense-related transcription factors WRKY70 and WRKY54 modulate osmotic stress tolerance by regulating stomatal aperture in Arabidopsis. THE NEW PHYTOLOGIST 2013; 200:457-472. [PMID: 23815736 PMCID: PMC4284015 DOI: 10.1111/nph.12378] [Citation(s) in RCA: 163] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2013] [Accepted: 05/21/2013] [Indexed: 05/20/2023]
Abstract
WRKY transcription factors (TFs) have been mainly associated with plant defense, but recent studies have suggested additional roles in the regulation of other physiological processes. Here, we explored the possible contribution of two related group III WRKY TFs, WRKY70 and WRKY54, to osmotic stress tolerance. These TFs are positive regulators of plant defense, and co-operate as negative regulators of salicylic acid (SA) biosynthesis and senescence. We employed single and double mutants of wrky54 and wrky70, as well as a WRKY70 overexpressor line, to explore the role of these TFs in osmotic stress (polyethylene glycol) responses. Their effect on gene expression was characterized by microarrays and verified by quantitative PCR. Stomatal phenotypes were assessed by water retention and stomatal conductance measurements. The wrky54wrky70 double mutants exhibited clearly enhanced tolerance to osmotic stress. However, gene expression analysis showed reduced induction of osmotic stress-responsive genes in addition to reduced accumulation of the osmoprotectant proline. By contrast, the enhanced tolerance was correlated with improved water retention and enhanced stomatal closure. These findings demonstrate that WRKY70 and WRKY54 co-operate as negative regulators of stomatal closure and, consequently, osmotic stress tolerance in Arabidopsis, suggesting that they have an important role, not only in plant defense, but also in abiotic stress signaling.
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Affiliation(s)
- Jing Li
- Viikki Biocenter, Division of Genetics, Department of Biosciences, University of Helsinki, FI-00014, Helsinki, Finland
| | - Sebastien Besseau
- Université François Rabelais de Tours, EA2106 Biomolécules et Biotechnologies Végétales, 37200, Tours, France
| | - Petri Törönen
- Viikki Biocenter, Division of Genetics, Department of Biosciences, University of Helsinki, FI-00014, Helsinki, Finland
- Institute of Biotechnology, University of Helsinki, FI-00014, Helsinki, Finland
| | - Nina Sipari
- Viikki Biocenter, Division of Genetics, Department of Biosciences, University of Helsinki, FI-00014, Helsinki, Finland
| | - Hannes Kollist
- Institute of Technology, University of Tartu, Nooruse 1, Tartu, 50411, Estonia
| | - Liisa Holm
- Viikki Biocenter, Division of Genetics, Department of Biosciences, University of Helsinki, FI-00014, Helsinki, Finland
- Institute of Biotechnology, University of Helsinki, FI-00014, Helsinki, Finland
| | - E Tapio Palva
- Viikki Biocenter, Division of Genetics, Department of Biosciences, University of Helsinki, FI-00014, Helsinki, Finland
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111
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Iakimova ET, Michaeli R, Woltering EJ. Involvement of phospholipase D-related signal transduction in chemical-induced programmed cell death in tomato cell cultures. PROTOPLASMA 2013; 250:1169-1183. [PMID: 23604388 DOI: 10.1007/s00709-013-0497-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2012] [Accepted: 02/27/2013] [Indexed: 06/02/2023]
Abstract
Phospholipase D (PLD) and its product phosphatidic acid (PA) are incorporated in a complex metabolic network in which the individual PLD isoforms are suggested to regulate specific developmental and stress responses, including plant programmed cell death (PCD). Despite the accumulating knowledge, the mechanisms through which PLD/PA operate during PCD are still poorly understood. In this work, the role of PLDα1 in PCD and the associated caspase-like proteolysis, ethylene and hydrogen peroxide (H(2)O(2)) synthesis in tomato suspension cells was studied. Wild-type (WT) and PLDα1-silenced cell lines were exposed to the cell death-inducing chemicals camptothecin (CPT), fumonisin B1 (FB1) and CdSO(4). A range of caspase inhibitors effectively suppressed CPT-induced PCD in WT cells, but failed to alleviate cell death in PLDα1-deficient cells. Compared to WT, in CPT-treated PLDα1 mutant cells, reduced cell death and decreased production of H(2)O(2) were observed. Application of ethylene significantly enhanced CPT-induced cell death both in WT and PLDα1 mutants. Treatments with the PA derivative lyso-phosphatidic acid and mastoparan (agonist of PLD/PLC signalling downstream of G proteins) caused severe cell death. Inhibitors, specific to PLD and PLC, remarkably decreased the chemical-induced cell death. Taken together with our previous findings, the results suggest that PLDα1 contributes to caspase-like-dependent cell death possibly communicated through PA, reactive oxygen species and ethylene. The dead cells expressed morphological features of PCD such as protoplast shrinkage and nucleus compaction. The presented findings reveal novel elements of PLD/PA-mediated cell death response and suggest that PLDα1 is an important factor in chemical-induced PCD signal transduction.
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Affiliation(s)
- Elena T Iakimova
- Plant Sciences Group, Horticultural Supply Chains, Wageningen University, P.O. Box 630, 6700 AP, Wageningen, The Netherlands
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112
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Danquah A, de Zelicourt A, Colcombet J, Hirt H. The role of ABA and MAPK signaling pathways in plant abiotic stress responses. Biotechnol Adv 2013; 32:40-52. [PMID: 24091291 DOI: 10.1016/j.biotechadv.2013.09.006] [Citation(s) in RCA: 325] [Impact Index Per Article: 29.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Revised: 09/14/2013] [Accepted: 09/20/2013] [Indexed: 01/12/2023]
Abstract
As sessile organisms, plants have developed specific mechanisms that allow them to rapidly perceive and respond to stresses in the environment. Among the evolutionarily conserved pathways, the ABA (abscisic acid) signaling pathway has been identified as a central regulator of abiotic stress response in plants, triggering major changes in gene expression and adaptive physiological responses. ABA induces protein kinases of the SnRK family to mediate a number of its responses. Recently, MAPK (mitogen activated protein kinase) cascades have also been shown to be implicated in ABA signaling. Therefore, besides discussing the role of ABA in abiotic stress signaling, we will also summarize the evidence for a role of MAPKs in the context of abiotic stress and ABA signaling.
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Affiliation(s)
- Agyemang Danquah
- URGV Plant Genomics, INRA-CNRS-UEVE, Saclay Plant Sciences, 2 rue Gaston Cremieux, 91000 Evry, France
| | - Axel de Zelicourt
- URGV Plant Genomics, INRA-CNRS-UEVE, Saclay Plant Sciences, 2 rue Gaston Cremieux, 91000 Evry, France
| | - Jean Colcombet
- URGV Plant Genomics, INRA-CNRS-UEVE, Saclay Plant Sciences, 2 rue Gaston Cremieux, 91000 Evry, France
| | - Heribert Hirt
- URGV Plant Genomics, INRA-CNRS-UEVE, Saclay Plant Sciences, 2 rue Gaston Cremieux, 91000 Evry, France
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113
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Zbierzak AM, Porfirova S, Griebel T, Melzer M, Parker JE, Dörmann P. A TIR-NBS protein encoded by Arabidopsis Chilling Sensitive 1 (CHS1) limits chloroplast damage and cell death at low temperature. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2013; 75:539-52. [PMID: 23617639 DOI: 10.1111/tpj.12219] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2013] [Revised: 04/18/2013] [Accepted: 04/22/2013] [Indexed: 05/26/2023]
Abstract
Survival of plants at low temperature depends on mechanisms for limiting physiological damage and maintaining growth. We mapped the chs1-1 (chilling sensitive1-1) mutation in Arabidopsis accession Columbia to the TIR-NBS gene At1g17610. In chs1-1, a single amino acid exchange at the CHS1 N-terminus close to the conserved TIR domain creates a stable mutant protein that fails to protect leaves against chilling stress. The sequence of another TIR-NBS gene (At5g40090) named CHL1 (CHS1-like 1) is related to that of CHS1. Over-expression of CHS1 or CHL1 alleviates chilling damage and enhances plant growth at moderate (24°C) and chilling (13°C) temperatures, suggesting a role for both proteins in growth homeostasis. chs1-1 mutants show induced salicylic acid production and defense gene expression at 13°C, indicative of autoimmunity. Genetic analysis of chs1-1 in combination with defense pathway mutants shows that chs1-1 chilling sensitivity requires the TIR-NBS-LRR and basal resistance regulators encoded by EDS1 and PAD4 but not salicylic acid. By following the timing of metabolic, physiological and chloroplast ultrastructural changes in chs1-1 leaves during chilling, we have established that alterations in photosynthetic complexes and thylakoid membrane integrity precede leaf cell death measured by ion leakage. At 24°C, the chs1-1 mutant appears normal but produces a massive necrotic response to virulent Pseudomonas syringae pv. tomato infection, although this does not affect bacterial proliferation. Our results suggest that CHS1 acts at an intersection between temperature sensing and biotic stress pathway activation to maintain plant performance over a range of conditions.
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Affiliation(s)
- Anna Maria Zbierzak
- Institute of Molecular Physiology and Biotechnology of Plants, University of Bonn, 53115, Bonn, Germany
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114
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Shi Y, Wang Z, Meng P, Tian S, Zhang X, Yang S. The glutamate carboxypeptidase AMP1 mediates abscisic acid and abiotic stress responses in Arabidopsis. THE NEW PHYTOLOGIST 2013; 199:135-150. [PMID: 23621575 DOI: 10.1111/nph.12275] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2013] [Accepted: 02/15/2013] [Indexed: 05/03/2023]
Abstract
ALTERED MERISTEM PROGRAM1 (AMP1) encodes a glutamate carboxypeptidase that plays an important role in shoot apical meristem development and phytohormone homeostasis. We isolated a new mutant allele of AMP1, amp1-20, from a screen for abscisic acid (ABA) hypersensitive mutants and characterized the function of AMP1 in plant stress responses. amp1 mutants displayed ABA hypersensitivity, while overexpression of AMP1 caused ABA insensitivity. Moreover, endogenous ABA concentration was increased in amp1-20- and decreased in AMP1-overexpressing plants under stress conditions. Application of ABA reduced the AMP1 protein level in plants. Interestingly, amp1 mutants accumulated excess superoxide and displayed hypersensitivity to oxidative stress. The hypersensitivity of amp1 to ABA and oxidative stress was partially rescued by reactive oxygen species (ROS) scavenging agent. Furthermore, amp1 was tolerant to freezing and drought stress. The ABA hypersensitivity and freezing tolerance of amp1 was dependent on ABA signaling. Moreover, amp1 had elevated soluble sugar content and showed hypersensitivity to high concentrations of sugar. By contrast, the contents of amino acids were changed in amp1 mutant compared to the wild-type. This study suggests that AMP1 modulates ABA, oxidative and abotic stress responses, and is involved in carbon and amino acid metabolism in Arabidopsis.
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Affiliation(s)
- Yiting Shi
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
| | - Zheng Wang
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
| | - Pei Meng
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
| | - Siqi Tian
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
| | - Xiaoyan Zhang
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
| | - Shuhua Yang
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
- Coordinated Research Center for Crop Biology, China Agricultural University, Beijing, 100193, China
- National Plant Gene Research Center, Beijing, 100193, China
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115
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Towards the identification of new genes involved in ABA-dependent abiotic stresses using Arabidopsis suppressor mutants of abh1 hypersensitivity to ABA during seed germination. Int J Mol Sci 2013; 14:13403-32. [PMID: 23807502 PMCID: PMC3742194 DOI: 10.3390/ijms140713403] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2013] [Revised: 05/20/2013] [Accepted: 06/06/2013] [Indexed: 01/23/2023] Open
Abstract
Abscisic acid plays a pivotal role in the abiotic stress response in plants. Although great progress has been achieved explaining the complexity of the stress and ABA signaling cascade, there are still many questions to answer. Mutants are a valuable tool in the identification of new genes or new alleles of already known genes and in elucidating their role in signaling pathways. We applied a suppressor mutation approach in order to find new components of ABA and abiotic stress signaling in Arabidopsis. Using the abh1 (ABA hypersensitive 1) insertional mutant as a parental line for EMS mutagenesis, we selected several mutants with suppressed hypersensitivity to ABA during seed germination. Here, we present the response to ABA and a wide range of abiotic stresses during the seed germination and young seedling development of two suppressor mutants—soa2 (suppressor of abh1 hypersensitivity to ABA 2) and soa3 (suppressor of abh1 hypersensitivity to ABA 3). Generally, both mutants displayed a suppression of the hypersensitivity of abh1 to ABA, NaCl and mannitol during germination. Both mutants showed a higher level of tolerance than Columbia-0 (Col-0—the parental line of abh1) in high concentrations of glucose. Additionally, soa2 exhibited better root growth than Col-0 in the presence of high ABA concentrations. soa2 and soa3 were drought tolerant and both had about 50% fewer stomata per mm2 than the wild-type but the same number as their parental line—abh1. Taking into account that suppressor mutants had the same genetic background as their parental line—abh1, it was necessary to backcross abh1 with Landsberg erecta four times for the map-based cloning approach. Mapping populations, derived from the cross of abh1 in the Landsberg erecta background with each suppressor mutant, were created. Map based cloning in order to identify the suppressor genes is in progress.
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116
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Kobayashi Y, Kobayashi Y, Sugimoto M, Lakshmanan V, Iuchi S, Kobayashi M, Bais HP, Koyama H. Characterization of the complex regulation of AtALMT1 expression in response to phytohormones and other inducers. PLANT PHYSIOLOGY 2013; 162:732-40. [PMID: 23624855 PMCID: PMC3668066 DOI: 10.1104/pp.113.218065] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
In Arabidopsis (Arabidopsis thaliana), malate released into the rhizosphere has various roles, such as detoxifying rhizotoxic aluminum (Al) and recruiting beneficial rhizobacteria that induce plant immunity. ALUMINUM-ACTIVATED MALATE TRANSPORTER1 (AtALMT1) is a critical gene in these responses, but its regulatory mechanisms remain unclear. To explore the mechanism of the multiple responses of AtALMT1, we profiled its expression patterns in wild-type plants, in transgenic plants harboring various deleted promoter constructs, and in mutant plants with defects in signal transduction in response to various inducers. AtALMT1 transcription was clearly induced by indole-3-acetic acid (IAA), abscisic acid (ABA), low pH, and hydrogen peroxide, indicating that it was able to respond to multiple signals, while it was not induced by methyl jasmonate and salicylic acid. The IAA-signaling double mutant nonphototropic hypocotyls4-1; auxin-responsive factor19-1 and the ABA-signaling mutant aba insensitive1-1 did not respond to auxin and ABA, respectively, but both showed an Al response comparable to that of the wild type. A synthetic microbe-associated molecular pattern peptide, flagellin22 (flg22), induced AtALMT1 transcription but did not induce the transcription of IAA- and ABA-responsive biomarker genes, indicating that both Al and flg22 responses of AtALMT1 were independent of IAA and ABA signaling. An in planta β-glucuronidase reporter assay identified that the ABA response was regulated by a region upstream (-317 bp) from the first ATG codon, but other stress responses may share critical regulatory element(s) located between -292 and -317 bp. These results illustrate the complex regulation of AtALMT1 expression during the adaptation to abiotic and biotic stresses.
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Miyakawa T, Fujita Y, Yamaguchi-Shinozaki K, Tanokura M. Structure and function of abscisic acid receptors. TRENDS IN PLANT SCIENCE 2013; 18:259-66. [PMID: 23265948 DOI: 10.1016/j.tplants.2012.11.002] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2012] [Revised: 10/26/2012] [Accepted: 11/01/2012] [Indexed: 05/18/2023]
Abstract
The phytohormone abscisic acid (ABA) plays a crucial role in adaptive responses to environmental stresses, such as drought and high salinity, as well as in plant development, such as seed maturation and dormancy. PYR/PYL/RCAR has been identified as a bona fide ABA receptor (ABAR) that constitutes the core regulatory component of ABA signaling networks in plants. Here, we review recent structural and functional studies of the ABAR that have elucidated its activation mechanism, early signaling components, and physiological responses. A crucial event in the receptor's activation was found to be an open-to-closed conformational change in the gate loop of the receptor protein. More recent progress has provided strategies for controlling the gate's closure using chemical agonists or protein engineering approaches.
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Affiliation(s)
- Takuya Miyakawa
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
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118
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Imes D, Mumm P, Böhm J, Al-Rasheid KAS, Marten I, Geiger D, Hedrich R. Open stomata 1 (OST1) kinase controls R-type anion channel QUAC1 in Arabidopsis guard cells. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2013; 74:372-82. [PMID: 23452338 DOI: 10.1111/tpj.12133] [Citation(s) in RCA: 126] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2012] [Revised: 01/21/2013] [Accepted: 01/23/2013] [Indexed: 05/08/2023]
Abstract
Under drought stress, the stress hormone ABA addresses the SnR kinase OST1 via its cytosolic receptor and the protein phosphatase ABI1. Upon activation, OST1 phosphorylates the guard cell S-type anion channel SLAC1. Arabidopsis ABI1 and OST1 loss-of-function mutants are characterized by an extreme wilting 'open stomata' phenotype. Given the fact that guard cells express both SLAC- and R-/QUAC-type anion channels, we questioned whether OST1, besides SLAC1, also controls the QUAC1 channel. In other words, are ABI1/OST1 defects preventing both of the guard cell anion channel types from operating properly in terms of stomatal closure? The activation of the R-/QUAC-type anion channel by ABA signaling kinase OST1 and phosphatase ABI1 was analyzed in two experimental systems: Arabidopsis guard cells and the plant cell-free background of Xenopus oocytes. Patch-clamp studies on guard cells show that ABA activates R-/QUAC-type currents of wild-type plants, but to a much lesser extent in those of abi1-1 and ost1-2 mutants. In the oocyte system the co-expression of QUAC1 and OST1 resulted in a pronounced activation of the R-type anion channel. These studies indicate that OST1 is addressing both S-/SLAC- and R-/QUAC-type guard cell anion channels, and explain why the ost1-2 mutant is much more sensitive to drought than single slac1 or quac1 mutants.
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Affiliation(s)
- Dennis Imes
- Molecular Plant Physiology and Biophysics, Julius-von-Sachs-Institute, University of Würzburg, Julius-von-Sachs Platz 2, D-97082, Würzburg, Germany
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119
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Jia HF, Lu D, Sun JH, Li CL, Xing Y, Qin L, Shen YY. Type 2C protein phosphatase ABI1 is a negative regulator of strawberry fruit ripening. JOURNAL OF EXPERIMENTAL BOTANY 2013; 64:1677-87. [PMID: 23404898 PMCID: PMC3617833 DOI: 10.1093/jxb/ert028] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Although a great deal of progress has been made toward understanding the role of abscisic acid (ABA) in fruit ripening, many components in the ABA signalling pathway remain to be elucidated. Here, a strawberry gene homologous to the Arabidopsis gene ABI1, named FaABI1, was isolated and characterized. The 1641bp cDNA includes an intact open reading frame that encodes a deduced protein of 546 amino acids, in which putative conserved domains were determined by homology analysis. Transcriptional analysis showed that the levels of FaABI1 mRNA expression declined rapidly during strawberry fruit development as evidenced by real-time PCR, semi-quantitative reverse transcription-PCR, and northern blotting analyses, suggesting that the Ser/Thr protein phosphatase PP2C1 encoded by FaABI1 may be involved in fruit ripening as a negative regulator. The results of Tobacco rattle virus-induced gene silencing and PBI121 vector-mediated overexpression suggested that the down- and up-regulation of FaABI1 mRNA expression levels in degreening strawberry fruit could promote and inhibit ripening, respectively. Furthermore, alteration of FaABI1 expression could differentially regulate the transcripts of a set of both ABA-responsive and ripening-related genes, including ABI3, ABI4, ABI5, SnRK2, ABRE1, CHS, PG1, PL, CHI, F3H, DFR, ANS, and UFGT. Taken together, the data provide new evidence for an important role for ABA in regulating strawberry fruit ripening in the processes of which the type 2C protein phosphatase ABI1 serves as a negative regulator. Finally, a possible core mechanism underlying ABA perception and signalling transduction in strawberry fruit ripening is discussed.
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MESH Headings
- Abscisic Acid
- Agrobacterium/metabolism
- Base Sequence
- DNA, Complementary/genetics
- DNA, Complementary/metabolism
- Fragaria/enzymology
- Fragaria/genetics
- Fragaria/growth & development
- Fruit/enzymology
- Fruit/genetics
- Fruit/growth & development
- Gene Expression Profiling
- Gene Expression Regulation, Enzymologic
- Gene Expression Regulation, Plant
- Gene Silencing
- Genes, Plant
- Molecular Sequence Data
- Open Reading Frames
- Phosphoprotein Phosphatases/genetics
- Phosphoprotein Phosphatases/metabolism
- Plant Proteins/genetics
- Plant Proteins/metabolism
- Protein Phosphatase 2C
- RNA, Messenger/analysis
- RNA, Messenger/genetics
- RNA, Plant/analysis
- RNA, Plant/genetics
- Recombinant Proteins/genetics
- Recombinant Proteins/metabolism
- Signal Transduction
- Transcription, Genetic
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Affiliation(s)
- Hai-Feng Jia
- Beijing Key Laboratory of New Technology in Agricultural Application, College of Plant Science and Technology, Beijing University of Agriculture, No. 7 Beinong Road, Changping District, Beijing 102206, PR China
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120
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Tezuka K, Taji T, Hayashi T, Sakata Y. A novel abi5 allele reveals the importance of the conserved Ala in the C3 domain for regulation of downstream genes and salt tolerance during germination in Arabidopsis. PLANT SIGNALING & BEHAVIOR 2013; 8:e23455. [PMID: 23299338 PMCID: PMC3676515 DOI: 10.4161/psb.23455] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Revised: 12/29/2012] [Accepted: 12/31/2012] [Indexed: 05/23/2023]
Abstract
Abscisic acid (ABA) signal transduction during Arabidopsis seed development and germination requires a Group A bZIP transcription factor encoded by ABA INSENSITIVE5 (ABI5). In addition to the basic leucine zipper DNA binding domain, Group A bZIPs are characterized by three N-terminal conserved regions (C1, C2 and C3) and one C-terminal conserved region (C4). These conserved regions are considered to play roles in ABI5 functions; however, except for the phosphorylation site, the importance of the highly conserved amino acids is unclear. Here, we report a novel abi5 recessive allele (abi5-9) that encodes an intact ABI5 protein with one amino acid substitution (A214G) in the C3 domain. The abi5-9 plants showed ABA insensitivity during germination and could germinate on medium containing 175 mM NaCl or 500 mM mannitol. Em1 and Em6--both encoding late embryogenesis abundant (LEA) proteins and directly targeted by ABI5 regulation--were expressed at very low levels in abi5-9 plants compared with the wild type. In yeast, the abi5-9 protein exhibited greatly reduced interaction with ABI3 compared with ABI5. These data suggest that Ala214 in ABI5 contributes to the function of ABI5 via its interaction with ABI3.
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Affiliation(s)
- Kenji Tezuka
- Department of BioScience; Tokyo University of Agriculture; Tokyo, Japan
- Department of Applied Biology and Chemistry; Faculty of Applied Biosciences; Tokyo University of Agriculture; Tokyo, Japan
| | - Teruaki Taji
- Department of BioScience; Tokyo University of Agriculture; Tokyo, Japan
- Department of Applied Biology and Chemistry; Faculty of Applied Biosciences; Tokyo University of Agriculture; Tokyo, Japan
| | - Takahisa Hayashi
- Department of BioScience; Tokyo University of Agriculture; Tokyo, Japan
- Department of Applied Biology and Chemistry; Faculty of Applied Biosciences; Tokyo University of Agriculture; Tokyo, Japan
| | - Yoichi Sakata
- Department of BioScience; Tokyo University of Agriculture; Tokyo, Japan
- Department of Applied Biology and Chemistry; Faculty of Applied Biosciences; Tokyo University of Agriculture; Tokyo, Japan
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121
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Leung J, Valon C, Moreau B, Boeglin M, Lefoulon C, Joshi-Saha A, Chérel I. [The ABC of abscisic acid action in plant drought stress responses]. Biol Aujourdhui 2013; 206:301-12. [PMID: 23419257 DOI: 10.1051/jbio/2012029] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Indexed: 11/14/2022]
Abstract
The combined daily consumption of fresh water ranges from 200 to 700 liters per capita per day in most developed countries, with about 70% being used for agricultural needs. Unlike other resources such as the different forms of energy, water has no other alternatives. With the looming prospect of global water crisis, the recent laudable success in deciphering the early steps in the signal transduction of the "stress hormone" abscisic acid (ABA) has ignited hopes that crops can be engineered with the capacity to maintain productivity while requiring less water input. Although ABA was first discovered in plants, it has resurfaced in the human brain (and many other non-plant organisms : sea sponge, some parasites, hydra to name a few), suggesting that its existence may be widespread. In humans, more amazingly, ABA has shown anti-inflammatory and antiviral properties. Even its receptors and key signaling intermediates have homologs in the human genome suggesting that evolution has re-fashioned these same proteins into new functional contexts. Thus, learning about the molecular mechanisms of ABA in action using the more flexible plant model will be likely beneficial to other organisms, and especially in human diseases, which is topical in the medical circle. ABA can accumulate up to 10 to 30-fold in plants under drought stress relative to unstressed conditions. The built up of the hormone then triggers diverse adaptive pathways permitting plants to withstand temporary bouts of water shortage. One favorite experimental model to unravel ABA signaling mechanisms in all of its intimate detail is based on the hormone's ability to elicit stomatal closure - a rapid cellular response of land plants to limit water loss through transpiration. Each microscopic stoma, or pore, is contoured by two specialized kidney-shaped cells called the guard cells. Because land plants are protected by a waxy cuticle impermeable to gas exchange, the stomatal pores are thus the primary portals for photosynthetic CO(2) uptake. Drought, by biasing pathways that lead to rapid closure of these pores, has therefore a negative impact on photosynthesis, and consequently, biomass as well. The stomatal aperture widens and narrows by expansion and contraction, respectively, of these flanking guard cells caused by changes in the intracellular concentrations of ion fluxes. These transport mechanisms most likely share fundamental principles with any excitable cell. These events require coordination of channels, vacuolar and membrane transporters that generate a specific pattern of electrical signals that relay the ABA stimulus. Research on ABA begun in the 1960's has now been crowned by the achievement of having identified the soluble ABA receptor that turns on and off the activities of a kinase/phosphatase pair, as the heart of the signaling complex. Results distilled from the latest structural studies on these ABA receptors, characterized by the so-called START domain, are beginning to tender the most exciting promise for rational design of agonists and antagonists towards modulating stress adaptive ability in plants. This review will chart the recent extraordinary progress that has enlightened us on how ABA controls membrane transport mechanisms that evoke the fast stomatal closing pathway.
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Affiliation(s)
- Jeffrey Leung
- Institut des Sciences du Végétal, Centre National de la Recherche Scientifique, Unité Propre de Recherche 2355, 1 Avenue de la Terrasse Bât. 23, 91198 Gif-sur-Yvette Cedex, France.
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122
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Dai M, Xue Q, Mccray T, Margavage K, Chen F, Lee JH, Nezames CD, Guo L, Terzaghi W, Wan J, Deng XW, Wang H. The PP6 phosphatase regulates ABI5 phosphorylation and abscisic acid signaling in Arabidopsis. THE PLANT CELL 2013; 25:517-34. [PMID: 23404889 PMCID: PMC3608775 DOI: 10.1105/tpc.112.105767] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2012] [Revised: 12/18/2012] [Accepted: 01/24/2013] [Indexed: 05/19/2023]
Abstract
The basic Leucine zipper transcription factor ABSCISIC ACID INSENSITIVE5 (ABI5) is a key regulator of abscisic acid (ABA)-mediated seed germination and postgermination seedling growth. While a family of SUCROSE NONFERMENTING1-related protein kinase2s (SnRK2s) is responsible for ABA-induced phosphorylation and stabilization of ABI5, the phosphatase(s) responsible for dephosphorylating ABI5 is still unknown. Here, we demonstrate that mutations in FyPP1 (for Phytochrome-associated serine/threonine protein phosphatase1) and FyPP3, two homologous genes encoding the catalytic subunits of Ser/Thr PROTEIN PHOSPHATASE6 (PP6), cause an ABA hypersensitive phenotype in Arabidopsis thaliana, including ABA-mediated inhibition of seed germination and seedling growth. Conversely, overexpression of FyPP causes reduced sensitivity to ABA. The ABA hypersensitive phenotype of FyPP loss-of-function mutants is ABI5 dependent, and the amount of phosphorylated and total ABI5 proteins inversely correlates with the levels of FyPP proteins. Moreover, FyPP proteins physically interact with ABI5 in vitro and in vivo, and the strength of the interaction depends on the ABI5 phosphorylation status. In vitro phosphorylation assays show that FyPP proteins directly dephosphorylate ABI5. Furthermore, genetic and biochemical assays show that FyPP proteins act antagonistically with SnRK2 kinases to regulate ABI5 phosphorylation and ABA responses. Thus, Arabidopsis PP6 phosphatase regulates ABA signaling through dephosphorylation and destabilization of ABI5.
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Affiliation(s)
- Mingqiu Dai
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, Connecticut 06520-8104
| | - Qin Xue
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, Connecticut 06520-8104
| | - Tyra Mccray
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, Connecticut 06520-8104
| | - Kathryn Margavage
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, Connecticut 06520-8104
- Department of Biology, Wilkes University, Wilkes-Barre, Pennsylvania 18766
| | - Fang Chen
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, Connecticut 06520-8104
| | - Jae-Hoon Lee
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, Connecticut 06520-8104
- Department of Biology Education, Pusan National University, Busan 609-735, Korea
| | - Cynthia D. Nezames
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, Connecticut 06520-8104
| | - Liquan Guo
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, Connecticut 06520-8104
- State Environmental Protection Key Laboratory of Wetland Ecology and Vegetation Restoration, Northeast Normal University, Changchun 130062, China
| | - William Terzaghi
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, Connecticut 06520-8104
- Department of Biology, Wilkes University, Wilkes-Barre, Pennsylvania 18766
| | - Jianmin Wan
- Institute of Crop Sciences, Chinese Academy of Agriculture Sciences, Beijing 100081, China
| | - Xing Wang Deng
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, Connecticut 06520-8104
- National Engineering Research Center for Crop Molecular Design, Beijing 100085, China
| | - Haiyang Wang
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, Connecticut 06520-8104
- Institute of Crop Sciences, Chinese Academy of Agriculture Sciences, Beijing 100081, China
- National Engineering Research Center for Crop Molecular Design, Beijing 100085, China
- College of Life Science, Capital Normal University, Beijing, 100048, China
- Address correspondence to
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123
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Duan L, Dietrich D, Ng CH, Chan PMY, Bhalerao R, Bennett MJ, Dinneny JR. Endodermal ABA signaling promotes lateral root quiescence during salt stress in Arabidopsis seedlings. THE PLANT CELL 2013; 25:324-41. [PMID: 23341337 PMCID: PMC3584545 DOI: 10.1105/tpc.112.107227] [Citation(s) in RCA: 252] [Impact Index Per Article: 22.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2012] [Revised: 12/19/2012] [Accepted: 12/30/2012] [Indexed: 05/18/2023]
Abstract
The endodermal tissue layer is found in the roots of vascular plants and functions as a semipermeable barrier, regulating the transport of solutes from the soil into the vascular stream. As a gateway for solutes, the endodermis may also serve as an important site for sensing and responding to useful or toxic substances in the environment. Here, we show that high salinity, an environmental stress widely impacting agricultural land, regulates growth of the seedling root system through a signaling network operating primarily in the endodermis. We report that salt stress induces an extended quiescent phase in postemergence lateral roots (LRs) whereby the rate of growth is suppressed for several days before recovery begins. Quiescence is correlated with sustained abscisic acid (ABA) response in LRs and is dependent upon genes necessary for ABA biosynthesis, signaling, and transcriptional regulation. We use a tissue-specific strategy to identify the key cell layers where ABA signaling acts to regulate growth. In the endodermis, misexpression of the ABA insensitive1-1 mutant protein, which dominantly inhibits ABA signaling, leads to a substantial recovery in LR growth under salt stress conditions. Gibberellic acid signaling, which antagonizes the ABA pathway, also acts primarily in the endodermis, and we define the crosstalk between these two hormones. Our results identify the endodermis as a gateway with an ABA-dependent guard, which prevents root growth into saline environments.
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Affiliation(s)
- Lina Duan
- Carnegie Institution for Science, Department of Plant Biology, Stanford, California 94305
- Temasek Lifesciences Laboratory, National University of Singapore, 117604, Singapore
- Department of Biological Sciences, National University of Singapore, 117604, Singapore
| | - Daniela Dietrich
- Plant Sciences Division, School of Biosciences, University of Nottingham, Loughborough LE12 5RD, United Kingdom
| | - Chong Han Ng
- Temasek Lifesciences Laboratory, National University of Singapore, 117604, Singapore
| | - Penny Mei Yeen Chan
- Temasek Lifesciences Laboratory, National University of Singapore, 117604, Singapore
- Department of Biological Sciences, National University of Singapore, 117604, Singapore
| | - Rishikesh Bhalerao
- Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, S-901 83 Umea, Sweden
| | - Malcolm J. Bennett
- Plant Sciences Division, School of Biosciences, University of Nottingham, Loughborough LE12 5RD, United Kingdom
| | - José R. Dinneny
- Carnegie Institution for Science, Department of Plant Biology, Stanford, California 94305
- Temasek Lifesciences Laboratory, National University of Singapore, 117604, Singapore
- Department of Biological Sciences, National University of Singapore, 117604, Singapore
- Address correspondence to
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124
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Abstract
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.
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Affiliation(s)
- Ruth Finkelstein
- Department of Molecular, Cellular and Developmental Biology, University of California at Santa Barbara, Santa Barbara, CA 93106 Address
- correspondence to e-mail:
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125
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Liese A, Romeis T. Biochemical regulation of in vivo function of plant calcium-dependent protein kinases (CDPK). BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2012; 1833:1582-9. [PMID: 23123193 DOI: 10.1016/j.bbamcr.2012.10.024] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2012] [Revised: 10/20/2012] [Accepted: 10/22/2012] [Indexed: 11/29/2022]
Abstract
Calcium (Ca(2+)) is a major second messenger in plant signal transduction mediating stress- and developmental processes. Plant Ca(2+)-dependent protein kinases (CDPKs) are mono-molecular Ca(2+)-sensor/protein kinase effector proteins, which perceive Ca(2+) signals and translate them into protein phosphorylation and thus represent an ideal tool for signal transduction. This review focuses on recent developments in CDPK structural analysis and CDPK in vivo phosphorylation substrate identification. We discuss mechanisms implicated in the in vivo regulation of CDPK activity including Ca(2+) binding to the CDPK EF-hands, Ca(2+)-triggered intra-molecular conformation changes, and CDPK (auto)-phosphorylation. Moreover, we address regulation and integration into signaling cascades of selected members of the plant CDPK family, for which in vivo function and phosphorylation in abiotic and biotic stress signaling have been demonstrated. This article is part of a Special Issue entitled: 12th European Symposium on Calcium.
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Affiliation(s)
- Anja Liese
- Dahlem Centre of Plant Sciences, FU Berlin, Plant Biochemistry, Berlin, Germany
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126
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Graeber K, Nakabayashi K, Miatton E, Leubner-Metzger G, Soppe WJJ. Molecular mechanisms of seed dormancy. PLANT, CELL & ENVIRONMENT 2012; 35:1769-86. [PMID: 22620982 DOI: 10.1111/j.1365-3040.2012.02542.x] [Citation(s) in RCA: 269] [Impact Index Per Article: 22.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Seed dormancy is an important component of plant fitness that causes a delay of germination until the arrival of a favourable growth season. Dormancy is a complex trait that is determined by genetic factors with a substantial environmental influence. Several of the tissues comprising a seed contribute to its final dormancy level. The roles of the plant hormones abscisic acid and gibberellin in the regulation of dormancy and germination have long been recognized. The last decade saw the identification of several additional factors that influence dormancy including dormancy-specific genes, chromatin factors and non-enzymatic processes. This review gives an overview of our present understanding of the mechanisms that control seed dormancy at the molecular level, with an emphasis on new insights. The various regulators that are involved in the induction and release of dormancy, the influence of environmental factors and the conservation of seed dormancy mechanisms between plant species are discussed. Finally, expected future directions in seed dormancy research are considered.
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Affiliation(s)
- Kai Graeber
- University of Freiburg, Faculty of Biology, Institute for Biology II, Botany/Plant Physiology, Freiburg, Germany
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127
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Kusakina J, Dodd AN. Phosphorylation in the plant circadian system. TRENDS IN PLANT SCIENCE 2012; 17:575-83. [PMID: 22784827 DOI: 10.1016/j.tplants.2012.06.008] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2012] [Revised: 06/13/2012] [Accepted: 06/14/2012] [Indexed: 05/17/2023]
Abstract
Circadian regulation is essential for optimum plant performance. In addition to loops and cascades of transcription and translation, the plant circadian clock and its associated signal transduction networks incorporate many post-translational mechanisms. Phosphorylation is a common feature of signal transduction and gene regulation. In this opinion article, we illustrate how phosphorylation events are positioned within the entrainment, functioning, and regulation of the circadian timing system. Phosphorylation regulates protein stability, protein-protein interactions and protein-DNA interactions within the core oscillator. We suggest that phosphorylation provides a potential mechanism for the distribution of circadian timing information within the cell and for the integration of circadian timing information with other signaling pathways.
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Affiliation(s)
- Jelena Kusakina
- Department of Biology, University of York, York YO10 5DD, UK
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128
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Abstract
Since the first recordings of single potassium channel activities in the plasma membrane of guard cells more than 25 years ago, patch-clamp studies discovered a variety of ion channels in all cell types and plant species under inspection. Their properties differed in a cell type- and cell membrane-dependent manner. Guard cells, for which the existence of plant potassium channels was initially documented, advanced to a versatile model system for studying plant ion channel structure, function, and physiology. Interestingly, one of the first identified potassium-channel genes encoding the Shaker-type channel KAT1 was shown to be highly expressed in guard cells. KAT1-type channels from Arabidopsis thaliana and its homologs from other species were found to encode the K+-selective inward rectifiers that had already been recorded in early patch-clamp studies with guard cells. Within the genome era, additional Arabidopsis Shaker-type channels appeared. All nine members of the Arabidopsis Shaker family are localized at the plasma membrane, where they either operate as inward rectifiers, outward rectifiers, weak voltage-dependent channels, or electrically silent, but modulatory subunits. The vacuole membrane, in contrast, harbors a set of two-pore K+ channels. Just very recently, two plant anion channel families of the SLAC/SLAH and ALMT/QUAC type were identified. SLAC1/SLAH3 and QUAC1 are expressed in guard cells and mediate Slow- and Rapid-type anion currents, respectively, that are involved in volume and turgor regulation. Anion channels in guard cells and other plant cells are key targets within often complex signaling networks. Here, the present knowledge is reviewed for the plant ion channel biology. Special emphasis is drawn to the molecular mechanisms of channel regulation, in the context of model systems and in the light of evolution.
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Affiliation(s)
- Rainer Hedrich
- University of Wuerzburg, Institute for Molecular Plant Physiology and Biophysics, Wuerzburg, Germany; and King Saud University, Riyadh, Saudi Arabia
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129
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Bhaskara GB, Nguyen TT, Verslues PE. Unique drought resistance functions of the highly ABA-induced clade A protein phosphatase 2Cs. PLANT PHYSIOLOGY 2012; 160:379-95. [PMID: 22829320 PMCID: PMC3440212 DOI: 10.1104/pp.112.202408] [Citation(s) in RCA: 197] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2012] [Accepted: 07/20/2012] [Indexed: 05/18/2023]
Abstract
Six Arabidopsis (Arabidopsis thaliana) clade A protein phosphatase 2Cs (PP2Cs) have established abscisic acid (ABA) signaling roles; however, phenotypic roles of the remaining three "HAI" PP2Cs, Highly ABA-Induced1 (HAI1), AKT1-Interacting PP2C1/HAI2, and HAI3, have remained unclear. HAI PP2C mutants had enhanced proline and osmoregulatory solute accumulation at low water potential, while mutants of other clade A PP2Cs had no or lesser effect on these drought resistance traits. hai1-2 also had increased expression of abiotic stress-associated genes, including dehydrins and late embryogenesis abundant proteins, but decreased expression of several defense-related genes. Conversely, the HAI PP2Cs had relatively less impact on several ABA sensitivity phenotypes. HAI PP2C single mutants were unaffected in ABA sensitivity, while double and triple mutants were moderately hypersensitive in postgermination ABA response but ABA insensitive in germination. The HAI PP2Cs interacted most strongly with PYL5 and PYL7 to -10 of the PYL/RCAR ABA receptor family, with PYL7 to -10 interactions being relatively little affected by ABA in yeast two-hybrid assays. HAI1 had especially limited PYL interaction. Reduced expression of the main HAI1-interacting PYLs at low water potential when HAI1 expression was strongly induced also suggests limited PYL regulation and a role of HAI1 activity in negatively regulating specific drought resistance phenotypes. Overall, the HAI PP2Cs had greatest effect on ABA-independent low water potential phenotypes and lesser effect on classical ABA sensitivity phenotypes. Both this and their distinct PYL interaction demonstrate a new level of functional differentiation among the clade A PP2Cs and a point of cross talk between ABA-dependent and ABA-independent drought-associated signaling.
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Wang WM, Ma XF, Zhang Y, Luo MC, Wang GL, Bellizzi M, Xiong XY, Xiao SY. PAPP2C interacts with the atypical disease resistance protein RPW8.2 and negatively regulates salicylic acid-dependent defense responses in Arabidopsis. MOLECULAR PLANT 2012; 5:1125-37. [PMID: 22334594 DOI: 10.1093/mp/sss008] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Many fungal and oomycete pathogens differentiate a feeding structure named the haustorium to extract nutrition from the plant epidermal cell. The atypical resistance (R) protein RPW8.2 activates salicylic acid (SA)-dependent, haustorium-targeted defenses against Golovinomyces spp., the causal agents of powdery mildew diseases on multiple plant species. How RPW8.2 activates defense remains uncharacterized. Here, we report that RPW8.2 interacts with the phytochrome-associated protein phosphatase type 2C (PAPP2C) in yeast and in planta as evidenced by co-immunoprecipitation and bimolecular fluorescence complementation assays. Down-regulation of PAPP2C by RNA interference (RNAi) in Col-0 plants lacking RPW8.2 leads to leaf spontaneous cell death and enhanced disease resistance to powdery mildew via the SA-dependent signaling pathway. Moreover, down-regulation of PAPP2C by RNAi in the RPW8.2 background results in strong HR-like cell death, which correlates with elevated RPW8.2 expression. We further demonstrate that hemagglutinin (HA)-tagged PAPP2C prepared from tobacco leaf cells transiently transformed with HA-PAPP2C possesses phosphatase activity. In addition, silencing a rice gene (Os04g0452000) homologous to PAPP2C also results in spontaneous cell death in rice. Combined, our results suggest that RPW8.2 is functionally connected with PAPP2C and that PAPP2C negatively regulates SA-dependent basal defense against powdery mildew in Arabidopsis.
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Affiliation(s)
- Wen-Ming Wang
- Institute for Bioscience and Biotechnology Research and Department of Plant Sciences and Landscape Architecture, University of Maryland, Rockville, MD 20850, USA
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Reconstitution of abscisic acid activation of SLAC1 anion channel by CPK6 and OST1 kinases and branched ABI1 PP2C phosphatase action. Proc Natl Acad Sci U S A 2012; 109:10593-8. [PMID: 22689970 DOI: 10.1073/pnas.1116590109] [Citation(s) in RCA: 318] [Impact Index Per Article: 26.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The plant hormone abscisic acid (ABA) is produced in response to abiotic stresses and mediates stomatal closure in response to drought via recently identified ABA receptors (pyrabactin resistance/regulatory component of ABA receptor; PYR/RCAR). SLAC1 encodes a central guard cell S-type anion channel that mediates ABA-induced stomatal closure. Coexpression of the calcium-dependent protein kinase 21 (CPK21), CPK23, or the Open Stomata 1 kinase (OST1) activates SLAC1 anion currents. However, reconstitution of ABA activation of any plant ion channel has not yet been attained. Whether the known core ABA signaling components are sufficient for ABA activation of SLAC1 anion channels or whether additional components are required remains unknown. The Ca(2+)-dependent protein kinase CPK6 is known to function in vivo in ABA-induced stomatal closure. Here we show that CPK6 robustly activates SLAC1-mediated currents and phosphorylates the SLAC1 N terminus. A phosphorylation site (S59) in SLAC1, crucial for CPK6 activation, was identified. The group A PP2Cs ABI1, ABI2, and PP2CA down-regulated CPK6-mediated SLAC1 activity in oocytes. Unexpectedly, ABI1 directly dephosphorylated the N terminus of SLAC1, indicating an alternate branched early ABA signaling core in which ABI1 targets SLAC1 directly (down-regulation). Furthermore, here we have successfully reconstituted ABA-induced activation of SLAC1 channels in oocytes using the ABA receptor pyrabactin resistant 1 (PYR1) and PP2C phosphatases with two alternate signaling cores including either CPK6 or OST1. Point mutations in ABI1 disrupting PYR1-ABI1 interaction abolished ABA signal transduction. Moreover, by addition of CPK6, a functional ABA signal transduction core from ABA receptors to ion channel activation was reconstituted without a SnRK2 kinase.
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Marguerit E, Brendel O, Lebon E, Van Leeuwen C, Ollat N. Rootstock control of scion transpiration and its acclimation to water deficit are controlled by different genes. THE NEW PHYTOLOGIST 2012; 194:416-429. [PMID: 22335501 DOI: 10.1111/j.1469-8137.2012.04059.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
The stomatal control of transpiration is one of the major strategies by which plants cope with water stress. Here, we investigated the genetic architecture of the rootstock control of scion transpiration-related traits over a period of 3 yr. The rootstocks studied were full sibs from a controlled interspecific cross (Vitis vinifera cv. Cabernet Sauvignon × Vitis riparia cv. Gloire de Montpellier), onto which we grafted a single scion genotype. After 10 d without stress, the water supply was progressively limited over a period of 10 d, and a stable water deficit was then applied for 15 d. Transpiration rate was estimated daily and a mathematical curve was fitted to its response to water deficit intensity. We also determined δ(13) C values in leaves, transpiration efficiency and water extraction capacity. These traits were then analysed in a multienvironment (year and water status) quantitative trait locus (QTL) analysis. Quantitative trait loci, independent of year and water status, were detected for each trait. One genomic region was specifically implicated in the acclimation of scion transpiration induced by the rootstock. The QTLs identified colocalized with genes involved in water deficit responses, such as those relating to ABA and hydraulic regulation. Scion transpiration rate and its acclimation to water deficit are thus controlled genetically by the rootstock, through different genetic architectures.
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Affiliation(s)
- Elisa Marguerit
- Bordeaux Sciences Agro, ISVV, EGFV, UMR 1287, F-33175 Gradignan, France
- Univ. Bordeaux, ISVV, EGFV, UMR 1287, F-33140 Villenave d'Ornon, France
- INRA, ISVV, EGFV, UMR 1287, F-33140 Villenave d'Ornon, France
| | - Oliver Brendel
- INRA, UMR 1137 Ecologie et Ecophysiologie Forestières, 54280 Champenoux, France
- Université de Lorraine, UMR 1137 Ecologie et Ecophysiologie Forestières, 54506 Vandoeuvre-les-Nancy, France
| | - Eric Lebon
- INRA, UMR 759 Laboratoire d'Ecophysiologie des Plantes sous Stress Environnementaux, 34060 Montpellier, France
| | - Cornelis Van Leeuwen
- Bordeaux Sciences Agro, ISVV, EGFV, UMR 1287, F-33175 Gradignan, France
- Univ. Bordeaux, ISVV, EGFV, UMR 1287, F-33140 Villenave d'Ornon, France
- INRA, ISVV, EGFV, UMR 1287, F-33140 Villenave d'Ornon, France
| | - Nathalie Ollat
- Bordeaux Sciences Agro, ISVV, EGFV, UMR 1287, F-33175 Gradignan, France
- Univ. Bordeaux, ISVV, EGFV, UMR 1287, F-33140 Villenave d'Ornon, France
- INRA, ISVV, EGFV, UMR 1287, F-33140 Villenave d'Ornon, France
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134
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The stomata frontline of plant interaction with the environment-perspectives from hormone regulation. ACTA ACUST UNITED AC 2012. [DOI: 10.1007/s11515-012-1193-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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135
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Desclos-Theveniau M, Arnaud D, Huang TY, Lin GJC, Chen WY, Lin YC, Zimmerli L. The Arabidopsis lectin receptor kinase LecRK-V.5 represses stomatal immunity induced by Pseudomonas syringae pv. tomato DC3000. PLoS Pathog 2012; 8:e1002513. [PMID: 22346749 PMCID: PMC3276567 DOI: 10.1371/journal.ppat.1002513] [Citation(s) in RCA: 116] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2011] [Accepted: 12/15/2011] [Indexed: 01/03/2023] Open
Abstract
Stomata play an important role in plant innate immunity by limiting pathogen entry into leaves but molecular mechanisms regulating stomatal closure upon pathogen perception are not well understood. Here we show that the Arabidopsis thaliana L-type lectin receptor kinase-V.5 (LecRK-V.5) negatively regulates stomatal immunity. Loss of LecRK-V.5 function increased resistance to surface inoculation with virulent bacteria Pseudomonas syringae pv tomato DC3000. Levels of resistance were not affected after infiltration-inoculation, suggesting that LecRK-V.5 functions at an early defense stage. By contrast, lines overexpressing LecRK-V.5 were more susceptible to Pst DC3000. Enhanced resistance in lecrk-V.5 mutants was correlated with constitutive stomatal closure, while increased susceptibility phenotypes in overexpression lines were associated with early stomatal reopening. Lines overexpressing LecRK-V.5 also demonstrated a defective stomatal closure after pathogen-associated molecular pattern (PAMP) treatments. LecRK-V.5 is rapidly expressed in stomatal guard cells after bacterial inoculation or treatment with the bacterial PAMP flagellin. In addition, lecrk-V.5 mutants guard cells exhibited constitutive accumulation of reactive oxygen species (ROS) and inhibition of ROS production opened stomata of lecrk-V.5. LecRK-V.5 is also shown to interfere with abscisic acid-mediated stomatal closure signaling upstream of ROS production. These results provide genetic evidences that LecRK-V.5 negatively regulates stomatal immunity upstream of ROS biosynthesis. Our data reveal that plants have evolved mechanisms to reverse bacteria-mediated stomatal closure to prevent long-term effect on CO2 uptake and photosynthesis. During their lifetime, plants face numerous pathogenic microbes. Plants recognize microbial pathogens via plant receptors and recognition leads to the activation of a general defense response. Some foliar pathogens such as bacteria enter plant leaves through natural surface openings such as stomata. To restrict bacterial entry, plants close stomata upon contact with bacteria. A better understanding of stomatal immunity may lead to development of crops with improved disease resistance. Here, we used the model plant Arabidopsis thaliana to study activation of defense responses after infection by Pseudomonas syringae pv. tomato (Pst) DC3000 bacteria. We found that a gene not previously known to function in the defense response, LecRK-V.5, is modulating Arabidopsis resistance. By studying plants with mutations in or overexpressing this gene, we show that LecRK-V.5 negatively regulates plant stomatal immunity to Pst DC3000. In addition, LecRK-V.5 is rapidly expressed at stomata upon activation of the general defense response. Plants with mutations in LecRK-V.5 also demonstrated constitutive accumulation of reactive oxygen species in stomatal guard cells. We conclude that LecRK-V.5 is a protein that negatively regulates closure of stomata upon bacterial infection.
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Affiliation(s)
- Marie Desclos-Theveniau
- Department of Life Science and Institute of Plant Biology, National Taiwan University, Taipei, Taiwan
| | - Dominique Arnaud
- Department of Life Science and Institute of Plant Biology, National Taiwan University, Taipei, Taiwan
| | - Ting-Yu Huang
- Department of Life Science and Institute of Plant Biology, National Taiwan University, Taipei, Taiwan
| | - Grace Jui-Chih Lin
- Department of Life Science and Institute of Plant Biology, National Taiwan University, Taipei, Taiwan
| | - Wei-Yen Chen
- Department of Life Science and Institute of Plant Biology, National Taiwan University, Taipei, Taiwan
| | - Yi-Chia Lin
- Department of Life Science and Institute of Plant Biology, National Taiwan University, Taipei, Taiwan
| | - Laurent Zimmerli
- Department of Life Science and Institute of Plant Biology, National Taiwan University, Taipei, Taiwan
- * E-mail:
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136
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Xu YH, Liu R, Yan L, Liu ZQ, Jiang SC, Shen YY, Wang XF, Zhang DP. Light-harvesting chlorophyll a/b-binding proteins are required for stomatal response to abscisic acid in Arabidopsis. JOURNAL OF EXPERIMENTAL BOTANY 2012; 63:1095-106. [PMID: 22143917 PMCID: PMC3276081 DOI: 10.1093/jxb/err315] [Citation(s) in RCA: 178] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2011] [Revised: 08/29/2011] [Accepted: 09/01/2011] [Indexed: 05/18/2023]
Abstract
The light-harvesting chlorophyll a/b binding proteins (LHCB) are perhaps the most abundant membrane proteins in nature. It is reported here that the down-regulation or disruption of any member of the LHCB family, LHCB1, LHCB2, LHCB3, LHCB4, LHCB5, or LHCB6, reduces responsiveness of stomatal movement to ABA, and therefore results in a decrease in plant tolerance to drought stress in Arabidopsis thaliana. By contrast, over-expression of a LHCB member, LHCB6, enhances stomatal sensitivity to ABA. In addition, the reactive oxygen species (ROS) homeostasis and a set of ABA-responsive genes are altered in the lhcb mutants. These data demonstrate that LHCBs play a positive role in guard cell signalling in response to ABA and suggest that they may be involved in ABA signalling partly by modulating ROS homeostasis.
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Affiliation(s)
- Yan-Hong Xu
- College of Biological Sciences, China Agricultural University, Beijing 100094, China
- Bioinformatics and Systems Biology Laboratory of the Ministry of Education, Scholl of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Rui Liu
- College of Biological Sciences, China Agricultural University, Beijing 100094, China
- Bioinformatics and Systems Biology Laboratory of the Ministry of Education, Scholl of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Lu Yan
- College of Biological Sciences, China Agricultural University, Beijing 100094, China
- Bioinformatics and Systems Biology Laboratory of the Ministry of Education, Scholl of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Zhi-Qiang Liu
- College of Biological Sciences, China Agricultural University, Beijing 100094, China
- Bioinformatics and Systems Biology Laboratory of the Ministry of Education, Scholl of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Shang-Chuan Jiang
- Bioinformatics and Systems Biology Laboratory of the Ministry of Education, Scholl of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Yuan-Yue Shen
- College of Biological Sciences, China Agricultural University, Beijing 100094, China
- Bioinformatics and Systems Biology Laboratory of the Ministry of Education, Scholl of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Xiao-Fang Wang
- Bioinformatics and Systems Biology Laboratory of the Ministry of Education, Scholl of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Da-Peng Zhang
- Bioinformatics and Systems Biology Laboratory of the Ministry of Education, Scholl of Life Sciences, Tsinghua University, Beijing 100084, China
- To whom correspondence should be addressed. E-mail:
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Santiago J, Dupeux F, Betz K, Antoni R, Gonzalez-Guzman M, Rodriguez L, Márquez JA, Rodriguez PL. Structural insights into PYR/PYL/RCAR ABA receptors and PP2Cs. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2012; 182:3-11. [PMID: 22118610 DOI: 10.1016/j.plantsci.2010.11.014] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2010] [Accepted: 11/30/2010] [Indexed: 05/08/2023]
Abstract
Abscisic acid (ABA) plays an essential function in plant physiology since it is required for biotic and abiotic stress responses as well as control of plant growth and development. A new family of soluble ABA receptors, named PYR/PYL/RCAR, has emerged as ABA sensors able to inhibit the activity of specific protein phosphatases type-2C (PP2Cs) in an ABA-dependent manner. The structural and functional mechanism by which ABA is perceived by these receptors and consequently leads to inhibition of the PP2Cs has been recently elucidated. The module PYR/PYL/RCAR-ABA-PP2C offers an elegant and unprecedented mechanism to control phosphorylation signaling cascades in a ligand-dependent manner. The knowledge of their three-dimensional structures paves the way to the design of ABA agonists able to modulate the plant stress response.
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Affiliation(s)
- Julia Santiago
- Instituto de Biología Molecular y Celular de Plantas, Consejo Superior de Investigaciones Científicas-Universidad Politécnica de Valencia. Avd de los Naranjos, Edificio CPI 8E, ES-46022 Valencia, Spain
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138
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Freschi L, Mercier H. Connecting Environmental Stimuli and Crassulacean Acid Metabolism Expression: Phytohormones and Other Signaling Molecules. PROGRESS IN BOTANY 2012. [DOI: 10.1007/978-3-642-22746-2_9] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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139
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Miyakawa T, Tanokura M. Regulatory mechanism of abscisic acid signaling. Biophysics (Nagoya-shi) 2011; 7:123-128. [PMID: 27857600 PMCID: PMC5036775 DOI: 10.2142/biophysics.7.123] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2011] [Accepted: 10/28/2011] [Indexed: 12/13/2022] Open
Abstract
Abscisic acid (ABA) is a major phytohormone that mediates the adaptation of plants to environmental stresses such as drought and regulates developmental signals such as seed maturation. Studies on ABA signaling have progressed rapidly since the recent discovery of PYR/PYL receptor proteins as soluble ABA receptors. In plant cells, the receptor receives ABA to inhibit the phosphatase activity of type 2C protein phosphatase (PP2C), which is the major negative regulator in ABA signaling. SNF1-related protein kinase 2 (SnRK2) is then released from negative regulation by PP2C, turning on ABA signals by the phosphorylation of downstream factors. Insights into the regulation of PYR/PYL receptor proteins is therefore required in order to control drought-stress tolerance in plants. This article reviews the regulatory mechanism of the ABA receptor by ABA and its selective agonist. Structural analyses of PYR/PYL receptors have clearly elucidated the mechanism of ABA perception of the receptor or the mechanism of interaction with PP2C that leads to inhibition of its phosphatase activity. Moreover, the structures of PYR/PYL receptors complexed with pyrabactin, a selective ABA agonist, have provided the structural basis of ABA agonism and antagonism.
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Affiliation(s)
- Takuya Miyakawa
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Masaru Tanokura
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
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140
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Joshi-Saha A, Valon C, Leung J. A Brand New START: Abscisic Acid Perception and Transduction in the Guard Cell. Sci Signal 2011; 4:re4. [DOI: 10.1126/scisignal.2002164] [Citation(s) in RCA: 124] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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141
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Liu CC, Liu CF, Wang HX, Shen ZY, Yang CP, Wei ZG. Identification and analysis of phosphorylation status of proteins in dormant terminal buds of poplar. BMC PLANT BIOLOGY 2011; 11:158. [PMID: 22074553 PMCID: PMC3234192 DOI: 10.1186/1471-2229-11-158] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2011] [Accepted: 11/11/2011] [Indexed: 05/20/2023]
Abstract
BACKGROUND Although there has been considerable progress made towards understanding the molecular mechanisms of bud dormancy, the roles of protein phosphorylation in the process of dormancy regulation in woody plants remain unclear. RESULTS We used mass spectrometry combined with TiO₂ phosphopeptide-enrichment strategies to investigate the phosphoproteome of dormant terminal buds (DTBs) in poplar (Populus simonii × P. nigra). There were 161 unique phosphorylated sites in 161 phosphopeptides from 151 proteins; 141 proteins have orthologs in Arabidopsis, and 10 proteins are unique to poplar. Only 34 sites in proteins in poplar did not match well with the equivalent phosphorylation sites of their orthologs in Arabidopsis, indicating that regulatory mechanisms are well conserved between poplar and Arabidopsis. Further functional classifications showed that most of these phosphoproteins were involved in binding and catalytic activity. Extraction of the phosphorylation motif using Motif-X indicated that proline-directed kinases are a major kinase group involved in protein phosphorylation in dormant poplar tissues. CONCLUSIONS This study provides evidence about the significance of protein phosphorylation during dormancy, and will be useful for similar studies on other woody plants.
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Affiliation(s)
- Chang-Cai Liu
- State Key Laboratory of Forest Genetics and Tree Breeding (Northeast Forestry University), 26 Hexing Road, Harbin 150040, China
- Laboratory for Chemical Defence and Microscale Analysis, P.O. Box 3, Zhijiang 443200, China
| | - Chang-Fu Liu
- Shenyang Agricultural University, Dongling Road 120, Shenyang, Liaoning 110866, China
| | - Hong-Xia Wang
- Institute of Basic Medical Sciences, National Center for Biomedical Analysis, 27 Taiping Road, Beijing 100850, China
| | - Zhi-Ying Shen
- Daqing Branch, Harbin Medical University, Daqing 163319, China
| | - Chuan-Ping Yang
- State Key Laboratory of Forest Genetics and Tree Breeding (Northeast Forestry University), 26 Hexing Road, Harbin 150040, China
| | - Zhi-Gang Wei
- State Key Laboratory of Forest Genetics and Tree Breeding (Northeast Forestry University), 26 Hexing Road, Harbin 150040, China
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Lisso J, Schröder F, Fisahn J, Müssig C. NFX1-LIKE2 (NFXL2) suppresses abscisic acid accumulation and stomatal closure in Arabidopsis thaliana. PLoS One 2011; 6:e26982. [PMID: 22073231 PMCID: PMC3207813 DOI: 10.1371/journal.pone.0026982] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2011] [Accepted: 10/05/2011] [Indexed: 01/06/2023] Open
Abstract
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 CO(2) 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.
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Affiliation(s)
- Janina Lisso
- University of Potsdam, Max Planck Institute of Molecular Plant Physiology, Potsdam-Golm, Germany
| | - Florian Schröder
- University of Potsdam, Max Planck Institute of Molecular Plant Physiology, Potsdam-Golm, Germany
| | - Joachim Fisahn
- Max Planck Institute of Molecular Plant Physiology, Potsdam-Golm, Germany
| | - Carsten Müssig
- University of Potsdam, Max Planck Institute of Molecular Plant Physiology, Potsdam-Golm, Germany
- * E-mail:
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143
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Hayashi M, Kinoshita T. Crosstalk between blue-light- and ABA-signaling pathways in stomatal guard cells. PLANT SIGNALING & BEHAVIOR 2011; 6:1662-4. [PMID: 22067996 PMCID: PMC3329330 DOI: 10.4161/psb.6.11.17800] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
We recently established an immunohistochemical method for the detection of blue light (BL)-induced and phototropin-mediated phosphorylation of plasma-membrane H+-ATPase in stomatal guard cells of Arabidopsis thaliana. This technique makes it possible to detect the phosphorylation/activation status of guard-cell H+-ATPase in the epidermis of a single rosette leaf, without the need to prepare guard-cell protoplasts (GCPs) from a large number of plants. Moreover, it can detect guard-cell responses under more natural and stress-free conditions compared to using GCPs. Taking advantage of these properties, we examined the effect of abscisic acid (ABA) on BL-induced phosphorylation of guard-cell H+-ATPase by using ABA-insensitive mutants. This revealed inhibition of BL-induced phosphorylation of guard-cell H+-ATPase via the early ABA-signaling components PYR/PYL/RCAR-PP2Cs-SnRK2s, which are known to be early ABA-signaling components for a wide range of ABA responses in plants.
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144
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Sun HL, Wang XJ, Ding WH, Zhu SY, Zhao R, Zhang YX, Xin Q, Wang XF, Zhang DP. Identification of an important site for function of the type 2C protein phosphatase ABI2 in abscisic acid signalling in Arabidopsis. JOURNAL OF EXPERIMENTAL BOTANY 2011; 62:5713-25. [PMID: 21885535 PMCID: PMC3223061 DOI: 10.1093/jxb/err274] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2011] [Revised: 08/02/2011] [Accepted: 08/05/2011] [Indexed: 05/20/2023]
Abstract
It is known that the clade A protein phosphatase 2Cs (PP2Cs), including ABI1 and ABI2 and other PP2C members, are key players that function directly downstream of the PYR/PYL/RCAR abscisic acid (ABA) receptors. Here, identification of a crucial site for function of ABI2 protein phosphatase in ABA signalling is reported. It was observed that a calcium-dependent protein kinase (CDPK) phosphorylation site-like motif (CPL) in the ABI2 molecule is required for the interactions of ABI2 with the two members of the ABA receptors PYL5 and PYL9 and with a downstream protein kinase SnRK2.6, and for the catalytic activity of ABI2 in vitro, as well as for the response of ABI2 to the ABA receptors PYL5/PYL9 in relation to the ABA receptor-induced inhibition of the ABI2 phosphatase activity. Further, genetic evidence was provided to demonstrate that this CPL is required for the function of ABI2 to mediate ABA signalling. These data reveal that this CPL is an important site necessary for both the phosphatase activity of ABI2 and the functional interaction between ABI2 and PYL5/9 ABA receptors, providing new information to understand primary events of ABA signal transduction.
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Affiliation(s)
- Hai-Li Sun
- College of Biological Sciences, China Agricultural University, Beijing 100094, China
- Protein Science Laboratory of the Ministry of Education, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Xiao-Jing Wang
- College of Biological Sciences, China Agricultural University, Beijing 100094, China
- Protein Science Laboratory of the Ministry of Education, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Wei-Hua Ding
- College of Biological Sciences, China Agricultural University, Beijing 100094, China
- Protein Science Laboratory of the Ministry of Education, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Sai-Yong Zhu
- College of Biological Sciences, China Agricultural University, Beijing 100094, China
- Protein Science Laboratory of the Ministry of Education, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Rui Zhao
- College of Biological Sciences, China Agricultural University, Beijing 100094, China
- Protein Science Laboratory of the Ministry of Education, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Yi-Xie Zhang
- College of Biological Sciences, China Agricultural University, Beijing 100094, China
- Protein Science Laboratory of the Ministry of Education, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Qi Xin
- College of Biological Sciences, China Agricultural University, Beijing 100094, China
- Protein Science Laboratory of the Ministry of Education, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Xiao-Fang Wang
- College of Biological Sciences, China Agricultural University, Beijing 100094, China
- Protein Science Laboratory of the Ministry of Education, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Da-Peng Zhang
- Protein Science Laboratory of the Ministry of Education, School of Life Sciences, Tsinghua University, Beijing 100084, China
- To whom correspondence should be addressed. E-mail:
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145
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Hossain MA, Munemasa S, Nakamura Y, Mori IC, Murata Y. K252a-sensitive protein kinases but not okadaic acid-sensitive protein phosphatases regulate methyl jasmonate-induced cytosolic Ca2+ oscillation in guard cells of Arabidopsis thaliana. JOURNAL OF PLANT PHYSIOLOGY 2011; 168:1901-1908. [PMID: 21665326 DOI: 10.1016/j.jplph.2011.05.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2010] [Revised: 05/11/2011] [Accepted: 05/12/2011] [Indexed: 05/30/2023]
Abstract
Methyl jasmonate (MeJA) induces stomatal closure similar to abscisic acid (ABA), and MeJA signaling in guard cells shares some signal components with ABA signaling. As part of this process, MeJA as well as ABA induce the elevation and oscillation of cytosolic free-calcium concentrations ([Ca(2+)](cyt)) in guard cells. While abscisic acid-induced [Ca(2+)](cyt) oscillation has been extensively studied, MeJA-induced [Ca(2+)](cyt) oscillation is less well understood. In this study, we investigated the effects of K252a (a broad-range protein kinase inhibitor) and okadaic acid (OA, a protein phosphatase 1 and 2A inhibitor) on MeJA-induced [Ca(2+)](cyt) oscillation in guard cells of Arabidopsis thaliana ecotype Columbia expressing the Ca(2+) reporter yellow cameleon 3.6. The protein kinase inhibitor K252a abolished MeJA-induced stomatal closure and reduced MeJA-elicited [Ca(2+)](cyt) oscillation. The protein phosphatase inhibitor OA, on the other hand, did not inhibit these processes. These results suggest that MeJA signaling involves activation of K252a-sensitive protein kinases upstream of [Ca(2+)](cyt) oscillation but not activation of an OA-sensitive protein phosphatase in guard cells of A. thaliana ecotype Columbia.
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Affiliation(s)
- Mohammad Anowar Hossain
- Graduate School of Natural Science and Technology, Okayama University, 1-1-1 Tsushima-Naka, Okayama 700-8530, Japan
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146
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Zhao R, Sun HL, Mei C, Wang XJ, Yan L, Liu R, Zhang XF, Wang XF, Zhang DP. The Arabidopsis Ca(2+) -dependent protein kinase CPK12 negatively regulates abscisic acid signaling in seed germination and post-germination growth. THE NEW PHYTOLOGIST 2011; 192:61-73. [PMID: 21692804 DOI: 10.1111/j.1469-8137.2011.03793.x] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
• Ca(2+) -dependent protein kinase (CDPK) is believed to be involved in abscisic acid (ABA) signaling, and several members of the Arabidopsis CDPK superfamily have been identified as positive ABA signaling regulators, but it remains unknown if CDPK negatively regulates ABA signaling. • Here, we investigated the function of an Arabidopsis (Arabidopsis thaliana) CDPK, CPK12, in ABA signaling pathway. • We generated Arabidopsis CPK12-RNAi lines, and observed that downregulation of CPK12 resulted in ABA hypersensitivity in seed germination and post-germination growth, and altered expression of a set of ABA-responsive genes. Expression assay showed that CPK12 was ubiquitously expressed and localized to both cytosol and nucleus. Biochemical assays showed that CPK12 interacted with, phosphorylated and stimulated a type 2C protein phosphatase ABI2, and phosphorylated two ABA-responsive transcription factors (ABF1 and ABF4) in vitro. • Our findings show that the Arabidopsis CPK12 is a negative ABA-signaling regulator in seed germination and post-germination growth, suggesting that different members of the CDPK family may constitute a regulation loop by functioning positively and negatively in ABA signal transduction.
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Affiliation(s)
- Rui Zhao
- College of Biological Sciences, China Agricultural University, 100094 Beijing, China
- Protein Science Laboratory of the Ministry of Education, School of Life Sciences, Tsinghua University, 100084 Beijing, China
| | - Hai-Li Sun
- College of Biological Sciences, China Agricultural University, 100094 Beijing, China
- Protein Science Laboratory of the Ministry of Education, School of Life Sciences, Tsinghua University, 100084 Beijing, China
| | - Chao Mei
- Protein Science Laboratory of the Ministry of Education, School of Life Sciences, Tsinghua University, 100084 Beijing, China
| | - Xiao-Jing Wang
- College of Biological Sciences, China Agricultural University, 100094 Beijing, China
- Protein Science Laboratory of the Ministry of Education, School of Life Sciences, Tsinghua University, 100084 Beijing, China
| | - Lu Yan
- College of Biological Sciences, China Agricultural University, 100094 Beijing, China
- Protein Science Laboratory of the Ministry of Education, School of Life Sciences, Tsinghua University, 100084 Beijing, China
| | - Rui Liu
- College of Biological Sciences, China Agricultural University, 100094 Beijing, China
- Protein Science Laboratory of the Ministry of Education, School of Life Sciences, Tsinghua University, 100084 Beijing, China
| | - Xiao-Feng Zhang
- Protein Science Laboratory of the Ministry of Education, School of Life Sciences, Tsinghua University, 100084 Beijing, China
| | - Xiao-Fang Wang
- College of Biological Sciences, China Agricultural University, 100094 Beijing, China
- Protein Science Laboratory of the Ministry of Education, School of Life Sciences, Tsinghua University, 100084 Beijing, China
| | - Da-Peng Zhang
- Protein Science Laboratory of the Ministry of Education, School of Life Sciences, Tsinghua University, 100084 Beijing, China
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147
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Du QS, Fan XW, Wang CH, Huang RB. A possible CO2 conducting and concentrating mechanism in plant stomata SLAC1 channel. PLoS One 2011; 6:e24264. [PMID: 21931667 PMCID: PMC3172217 DOI: 10.1371/journal.pone.0024264] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2011] [Accepted: 08/07/2011] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND The plant SLAC1 is a slow anion channel in the membrane of stomatal guard cells, which controls the turgor pressure in the aperture-defining guard cells, thereby regulating the exchange of water vapour and photosynthetic gases in response to environmental signals such as drought, high levels of carbon dioxide, and bacterial invasion. Recent study demonstrated that bicarbonate is a small-molecule activator of SLAC1. Higher CO(2) and HCO(3)(-) concentration activates S-type anion channel currents in wild-type Arabidopsis guard cells. Based on the SLAC1 structure a theoretical model is derived to illustrate the activation of bicarbonate to SLAC1 channel. Meanwhile a possible CO(2) conducting and concentrating mechanism of the SLAC1 is proposed. METHODOLOGY The homology structure of Arabidopsis thaliana SLAC1 (AtSLAC1) provides the structural basis for study of the conducting and concentrating mechanism of carbon dioxide in SLAC1 channels. The pK(a) values of ionizable amino acid side chains in AtSLAC1 are calculated using software PROPKA3.0, and the concentration of CO(2) and anion HCO(3)(-) are computed based on the chemical equilibrium theory. CONCLUSIONS The AtSLAC1 is modeled as a five-region channel with different pH values. The top and bottom layers of channel are the alkaline residue-dominated regions, and in the middle of channel there is the acidic region surrounding acidic residues His332. The CO(2) concentration is enhanced around 10(4) times by the pH difference between these regions, and CO(2) is stored in the hydrophobic region, which is a CO(2) pool. The pH driven CO(2) conduction from outside to inside balances the back electromotive force and maintain the influx of anions (e.g. Cl(-) and NO(3)(-)) from inside to outside. SLAC1 may be a pathway providing CO(2) for photosynthesis in the guard cells.
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Affiliation(s)
- Qi-Shi Du
- National Engineering Research Center for Non-Food Biorefinery, Guangxi Academy of Sciences, Nanning, China.
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148
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Ying S, Zhang DF, Li HY, Liu YH, Shi YS, Song YC, Wang TY, Li Y. Cloning and characterization of a maize SnRK2 protein kinase gene confers enhanced salt tolerance in transgenic Arabidopsis. PLANT CELL REPORTS 2011; 30:1683-99. [PMID: 21638061 DOI: 10.1007/s00299-011-1077-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2011] [Revised: 03/22/2011] [Accepted: 04/19/2011] [Indexed: 05/11/2023]
Abstract
SnRK2 (sucrose non-fermenting 1-related protein kinases 2) represents a unique family of protein kinase in regulating signaling transduction in plants. Although the regulatory mechanisms of SnRK2 have been well demonstrated in Arabidopsis thaliana, their functions in maize are still unknown. In our study, we cloned an SnRK2 gene from maize, ZmSAPK8, which encoded a putative homolog of the rice SAPK8 protein. ZmSAPK8 had two copies in the maize genome and harbored eight introns in its coding region. We demonstrated that ZmSAPK8 expressed differentially in various organs of maize plants and was up-regulated by high-salinity and drought treatment. A green fluorescent protein (GFP)-tagged ZmSAPK8 showed subcellular localization in the cell membrane, cytoplasm and nucleus. In vitro kinase assays indicated that ZmSAPK8 preferred Mn(2+) to Mg(2+) as cofactor for phosphorylation, and Ser-182 and Thr-183 in activation loop was important for its activity. Heterologous overexpression of ZmSAPK8 in Arabidopsis could significantly strengthen tolerance to salt stress. Under salt treatment, ZmSAPK8-overexpressed transgenic plants exhibited higher germination rate and proline content, low electrolyte leakage and higher survival rate than wild type. Further analysis indicated that transgenic plants showed increased transcription of the stress-related genes, RD29A, RD29B, RAB18, ABI1, DREB2A and P5CS1, under high-salinity conditions. The results demonstrated that ZmSAPK8 was involved in diverse stress signal transduction. Moreover, no obvious adverse effects on growth and development in the ZmSAPK8-overexpressed transgenic plants implied that ZmSAPK8 was potentially useful in transgenic breeding to improve salt tolerance in crops.
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MESH Headings
- Amino Acid Sequence
- Arabidopsis/drug effects
- Arabidopsis/genetics
- Arabidopsis/metabolism
- Arabidopsis/physiology
- Cloning, Molecular
- DNA, Complementary/genetics
- Electrolytes/metabolism
- Enzyme Activation
- Gene Expression Regulation, Plant
- Genes, Plant
- Germination
- Manganese/metabolism
- Molecular Sequence Data
- Mutagenesis, Site-Directed
- Phosphorylation
- Phylogeny
- Plants, Genetically Modified/drug effects
- Plants, Genetically Modified/genetics
- Plants, Genetically Modified/metabolism
- Plants, Genetically Modified/physiology
- Protein Serine-Threonine Kinases/genetics
- Protein Serine-Threonine Kinases/metabolism
- Recombinant Fusion Proteins/metabolism
- Salt Tolerance
- Signal Transduction
- Sodium Chloride/pharmacology
- Stress, Physiological
- Transcription, Genetic
- Up-Regulation
- Zea mays/drug effects
- Zea mays/genetics
- Zea mays/metabolism
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Affiliation(s)
- Sheng Ying
- College of Biological Sciences, China Agricultural University, Beijing 100193, China
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149
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Dupeux F, Santiago J, Betz K, Twycross J, Park SY, Rodriguez L, Gonzalez-Guzman M, Jensen MR, Krasnogor N, Blackledge M, Holdsworth M, Cutler SR, Rodriguez PL, Márquez JA. A thermodynamic switch modulates abscisic acid receptor sensitivity. EMBO J 2011; 30:4171-84. [PMID: 21847091 DOI: 10.1038/emboj.2011.294] [Citation(s) in RCA: 126] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2011] [Accepted: 07/21/2011] [Indexed: 02/05/2023] Open
Abstract
Abscisic acid (ABA) is a key hormone regulating plant growth, development and the response to biotic and abiotic stress. ABA binding to pyrabactin resistance (PYR)/PYR1-like (PYL)/Regulatory Component of Abscisic acid Receptor (RCAR) intracellular receptors promotes the formation of stable complexes with certain protein phosphatases type 2C (PP2Cs), leading to the activation of ABA signalling. The PYR/PYL/RCAR family contains 14 genes in Arabidopsis and is currently the largest plant hormone receptor family known; however, it is unclear what functional differentiation exists among receptors. Here, we identify two distinct classes of receptors, dimeric and monomeric, with different intrinsic affinities for ABA and whose differential properties are determined by the oligomeric state of their apo forms. Moreover, we find a residue in PYR1, H60, that is variable between family members and plays a key role in determining oligomeric state. In silico modelling of the ABA activation pathway reveals that monomeric receptors have a competitive advantage for binding to ABA and PP2Cs. This work illustrates how receptor oligomerization can modulate hormonal responses and more generally, the sensitivity of a ligand-dependent signalling system.
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Affiliation(s)
- Florine Dupeux
- European Molecular Biology Laboratory, Grenoble Outstation and Unit of Virus Host-Cell Interactions, UJF-EMBL-CNRS, Grenoble Cedex 9, France
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150
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Coudert Y, Bès M, Le TVA, Pré M, Guiderdoni E, Gantet P. Transcript profiling of crown rootless1 mutant stem base reveals new elements associated with crown root development in rice. BMC Genomics 2011; 12:387. [PMID: 21806801 PMCID: PMC3163228 DOI: 10.1186/1471-2164-12-387] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2010] [Accepted: 08/01/2011] [Indexed: 12/17/2022] Open
Abstract
Background In rice, the major part of the post-embryonic root system is made of stem-derived roots named crown roots (CR). Among the few characterized rice mutants affected in root development, crown rootless1 mutant is unable to initiate crown root primordia. CROWN ROOTLESS1 (CRL1) is induced by auxin and encodes an AS2/LOB-domain transcription factor that acts upstream of the gene regulatory network controlling CR development. Results To identify genes involved in CR development, we compared global gene expression profile in stem bases of crl1 mutant and wild-type (WT) plants. Our analysis revealed that 250 and 236 genes are down- and up-regulated respectively in the crl1 mutant. Auxin induces CRL1 expression and consequently it is expected that auxin also alters the expression of genes that are early regulated by CRL1. To identify genes under the early control of CRL1, we monitored the expression kinetics of a selected subset of genes, mainly chosen among those exhibiting differential expression, in crl1 and WT following exogenous auxin treatment. This analysis revealed that most of these genes, mainly related to hormone, water and nutrient, development and homeostasis, were likely not regulated directly by CRL1. We hypothesized that the differential expression for these genes observed in the crl1 mutant is likely a consequence of the absence of CR formation. Otherwise, three CRL1-dependent auxin-responsive genes: FSM (FLATENNED SHOOT MERISTEM)/FAS1 (FASCIATA1), GTE4 (GENERAL TRANSCRIPTION FACTOR GROUP E4) and MAP (MICROTUBULE-ASSOCIATED PROTEIN) were identified. FSM/FAS1 and GTE4 are known in rice and Arabidopsis to be involved in the maintenance of root meristem through chromatin remodelling and cell cycle regulation respectively. Conclusion Our data showed that the differential regulation of most genes in crl1 versus WT may be an indirect consequence of CRL1 inactivation resulting from the absence of CR in the crl1 mutant. Nevertheless some genes, FAS1/FSM, GTE4 and MAP, require CRL1 to be induced by auxin suggesting that they are likely directly regulated by CRL1. These genes have a function related to polarized cell growth, cell cycle regulation or chromatin remodelling. This suggests that these genes are controlled by CRL1 and involved in CR initiation in rice.
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Affiliation(s)
- Yoan Coudert
- Université Montpellier 2, UMR DAP, Place Eugène Bataillon, 34095 Montpellier Cedex 5, France
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