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Tak H, Negi S, Ganapathi TR. The 5'-upstream region of WRKY18 transcription factor from banana is a stress-inducible promoter with strong expression in guard cells. PHYSIOLOGIA PLANTARUM 2021; 173:1335-1350. [PMID: 33421142 DOI: 10.1111/ppl.13326] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Revised: 12/07/2020] [Accepted: 12/24/2020] [Indexed: 06/12/2023]
Abstract
Increasing crop productivity in an ever-changing environmental scenario is a major challenge for maintaining the food supply worldwide. Generation of crops having broad-spectrum pathogen resistance with the ability to cope with water scarcity is the only solution to feed the expanding world population. Stomatal closure has implications on pathogen colonization and drought tolerance. Recent studies have provided novel insights into networks involved in stomatal closure which is being used in biotechnological applications for improving crop endurance. Despite that genetic engineering of stomata requires guard cell preferred or specific regulatory regions to avoid undesirable side effects. In the present study, we describe the 5'-upstream regulatory region of the WRKY18 transcription factor of banana and functionally analyzed its stress meditated activation and strong guard cell preferred activity. Expression of MusaWRKY18 is augmented in leaves of banana cultivars Karibale Monthan, Rasthali and Grand Nain under multiple stress conditions suggesting its role in stress responses of banana plants. Transgenic tobacco lines harboring PMusaWRKY18 -β-D-glucuronidase (GUS) were regenerated and GUS staining demonstrated substantial GUS expression in guard cells which corroborates with multiple Dof1 binding cis-elements in PMusaWRKY18 . Fluorescent β-galactosidase assay demonstrated the stress-mediated strong induction profiles of PMusaWRKY18 at different time points in transgenic tobacco lines exposed to drought, high-salinity, cold, and applications of abscisic acid, salicylic acid, methyl jasmonate, and ethephon. This study sheds novel insights into guard cell preferred expression of WRKY genes under stress and confirm the utility of PMusaWRKY18 for exploring guard cell functions and guard cell engineering.
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Affiliation(s)
- Himanshu Tak
- Plant Cell Culture Technology Section, Nuclear Agriculture and Biotechnology Division, Bhabha Atomic Research Centre, Mumbai, India
- Homi Bhabha National Institute, Mumbai, India
| | - Sanjana Negi
- Department of Biotechnology, University of Mumbai, Mumbai, India
| | - Thumballi R Ganapathi
- Plant Cell Culture Technology Section, Nuclear Agriculture and Biotechnology Division, Bhabha Atomic Research Centre, Mumbai, India
- Homi Bhabha National Institute, Mumbai, India
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2
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Spatial and Temporal Calcium Signaling and Its Physiological Effects in Moso Bamboo under Drought Stress. FORESTS 2019. [DOI: 10.3390/f10030224] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Elevations in cytosolic free calcium concentration constitute a fundamental signal transduction mechanism in plants; however, the particular characteristics of calcium ion (Ca2+) signal occurrence in plants is still under debate. Little is known about how stimulus-specific Ca2+ signal fluctuations are generated. Therefore, we investigated the identity of the Ca2+ signal generation pathways, influencing factors, and the effects of the signaling network under drought stress on Phyllostachys edulis (Carrière) J. Houz. Non-invasive micro testing and laser confocal microscopy technology were used as platforms to detect and record Ca2+ signaling in live root tip and leaf cells of P. edulis under drought stress. We found that Ca2+ signal intensity (absorption capacity) positively correlated with degree of drought stress in the P. edulis shoots, and that Ca2+ signals in different parts of the root tip of P. edulis were different when emitted in response to drought stress. This difference was reflected in the Ca2+ flux and in regional distribution of Ca2+. Extracellular Ca2+ transport requires the involvement of the plasma membrane Ca2+ channels, while abscisic acid (ABA) can activate the plasma membrane Ca2+ channels. Additionally, Ca2+ acted as the upstream signal of H2O2 in the signaling network of P. edulis under drought stress. Ca2+ was also involved in the signal transduction process of ABA, and ABA can promote the production of Ca2+ signals in P. edulis leaves. Our findings revealed the physiological role of Ca2+ in drought resistance of P. edulis. This study establishes a theoretical foundation for research on the response to Ca2+ signaling in P. edulis.
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3
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Liu Y, Zhang A, Yin H, Meng Q, Yu X, Huang S, Wang J, Ahmad R, Liu B, Xu ZY. Trithorax-group proteins ARABIDOPSIS TRITHORAX4 (ATX4) and ATX5 function in abscisic acid and dehydration stress responses. THE NEW PHYTOLOGIST 2018; 217:1582-1597. [PMID: 29250818 DOI: 10.1111/nph.14933] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Accepted: 11/02/2017] [Indexed: 05/10/2023]
Abstract
Trithorax-group proteins (TrxGs) play essential regulatory roles in chromatin modification to activate transcription. Although TrxGs have been shown to be extensively involved in the activation of developmental genes, how the specific TrxGs function in the dehydration and abscisic acid (ABA)-mediated modulation of downstream gene expression remains unknown. Here, we report that two evolutionarily conserved Arabidopsis thaliana TrxGs, ARABIDOPSIS TRITHORAX4 (ATX4) and ATX5, play essential roles in the drought stress response. atx4 and atx5 single loss-of-function mutants showed drought stress-tolerant and ABA-hypersensitive phenotypes during seed germination and seedling development, while the atx4 atx5 double mutant displayed further exacerbation of the phenotypes. Genome-wide RNA-sequencing analyses showed that ATX4 and ATX5 regulate the expression of genes functioning in dehydration stress. Intriguingly, ABA-HYPERSENSITIVE GERMINATION 3 (AHG3), an essential negative regulator of ABA signaling, acts genetically downstream of ATX4 and ATX5 in response to ABA. ATX4 and ATX5 directly bind to the AHG3 locus and trimethylate histone H3 of Lys 4 (H3K4). Moreover, ATX4 and ATX5 occupancies at AHG3 are dramatically increased under ABA treatment, and are also essential for RNA polymerase II (RNAPII) occupancies. Our findings reveal novel molecular functions of A. thaliana TrxGs in dehydration stress and ABA responses.
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Affiliation(s)
- Yutong Liu
- Key Laboratory of Molecular Epigenetics of the Ministry of Education (MOE), Northeast Normal University, Changchun, 130024, China
| | - Ai Zhang
- Key Laboratory of Molecular Epigenetics of the Ministry of Education (MOE), Northeast Normal University, Changchun, 130024, China
| | - Hao Yin
- Key Laboratory of Molecular Epigenetics of the Ministry of Education (MOE), Northeast Normal University, Changchun, 130024, China
| | - Qingxiang Meng
- Key Laboratory of Molecular Epigenetics of the Ministry of Education (MOE), Northeast Normal University, Changchun, 130024, China
| | - Xiaoming Yu
- Key Laboratory of Molecular Epigenetics of the Ministry of Education (MOE), Northeast Normal University, Changchun, 130024, China
| | - Shuangzhan Huang
- Key Laboratory of Molecular Epigenetics of the Ministry of Education (MOE), Northeast Normal University, Changchun, 130024, China
| | - Jie Wang
- Key Laboratory of Molecular Epigenetics of the Ministry of Education (MOE), Northeast Normal University, Changchun, 130024, China
| | - Rafiq Ahmad
- Key Laboratory of Molecular Epigenetics of the Ministry of Education (MOE), Northeast Normal University, Changchun, 130024, China
| | - Bao Liu
- Key Laboratory of Molecular Epigenetics of the Ministry of Education (MOE), Northeast Normal University, Changchun, 130024, China
| | - Zheng-Yi Xu
- Key Laboratory of Molecular Epigenetics of the Ministry of Education (MOE), Northeast Normal University, Changchun, 130024, China
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4
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Dubovskaya LV, Bakakina YS, Kolesneva EV, Sodel DL, McAinsh MR, Hetherington AM, Volotovski ID. cGMP-dependent ABA-induced stomatal closure in the ABA-insensitive Arabidopsis mutant abi1-1. THE NEW PHYTOLOGIST 2011; 191:57-69. [PMID: 21371039 DOI: 10.1111/j.1469-8137.2011.03661.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
• The drought hormone abscisic acid (ABA) is widely known to produce reductions in stomatal aperture in guard cells. The second messenger cyclic guanosine 3', 5'-monophosphate (cGMP) is thought to form part of the signalling pathway by which ABA induces stomatal closure. • We have examined the signalling events during cGMP-dependent ABA-induced stomatal closure in wild-type Arabidopsis plants and plants of the ABA-insensitive Arabidopsis mutant abi1-1. • We show that cGMP acts downstream of hydrogen peroxide (H(2) O(2) ) and nitric oxide (NO) in the signalling pathway by which ABA induces stomatal closure. H(2) O(2) - and NO-induced increases in the cytosolic free calcium concentration ([Ca(2+) ](cyt) ) were cGMP-dependent, positioning cGMP upstream of [Ca(2+) ](cyt) , and involved the action of the type 2C protein phosphatase ABI1. Increases in cGMP were mediated through the stimulation of guanylyl cyclase by H(2) O(2) and NO. We identify nucleoside diphosphate kinase as a new cGMP target protein in Arabidopsis. • This study positions cGMP downstream of ABA-induced changes in H(2) O(2) and NO, and upstream of increases in [Ca(2+) ](cyt) in the signalling pathway leading to stomatal closure.
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Affiliation(s)
- Lyudmila V Dubovskaya
- National Academy of Sciences of Belarus, Institute of Biophysics and Cell Engineering, Minsk 220072, Academicheskaya 27, Belarus
| | - Yulia S Bakakina
- National Academy of Sciences of Belarus, Institute of Biophysics and Cell Engineering, Minsk 220072, Academicheskaya 27, Belarus
| | - Ekaterina V Kolesneva
- National Academy of Sciences of Belarus, Institute of Biophysics and Cell Engineering, Minsk 220072, Academicheskaya 27, Belarus
| | - Dmitry L Sodel
- National Academy of Sciences of Belarus, Institute of Biophysics and Cell Engineering, Minsk 220072, Academicheskaya 27, Belarus
| | - Martin R McAinsh
- Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, UK
| | | | - Igor D Volotovski
- National Academy of Sciences of Belarus, Institute of Biophysics and Cell Engineering, Minsk 220072, Academicheskaya 27, Belarus
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5
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Abstract
Recent work shows that transcription factors are necessary for stomatal movements in plants. Different members of the plant-specific R2R3-MYB transcription factor family are required for mediating stomatal opening in response to light and stomatal closure in response to darkness.
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Affiliation(s)
- Julie Gray
- Department of Molecular Biology and Biotechnology, University of Sheffield Firth Court, Western Bank, Sheffield S10 2TN, UK.
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6
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Li J, Gong X, Lin H, Song Q, Chen J, Wang X. DGP1, a drought-induced guard cell-specific promoter and its function analysis in tobacco plants. SCIENCE IN CHINA. SERIES C, LIFE SCIENCES 2005; 48:181-6. [PMID: 15986891 DOI: 10.1007/bf02879671] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
The genetic regulation of stomatal movement mainly depends on an efficient control system of gene expression, and guard cell-specific promoter is becoming the best choice. Here we combined the dehydration responsive element (DRE) with guard cell specific element (GCSE) to construct a novel promoter, DGP1. Histochemical assays in transgenic tobacco carrying beta, -glucuronidase (gus) gene fused to DGP1 demonstrated that GUS activity was found to be highly inducible by drought treatment and specifically restricted to guard cells. No GUS activity was detected in roots, stems or flowers after treatment. Further quantitative analysis showed that GUS activity in the epidermal strips was apparently induced by dehydration and dramatically increased with the elongation of treatment. The GUS activity after 8 h treatment was 179 times that of those without treatment. Although GUS activity in roots, stems or mesophyll increased after treatment, no great changes were observed. These results suggested that DGP1 could drive target gene expressed in guard cells when plant is subjected to drought stress. And this gets us prepared to control opening and closing of stomata through plant gene engineering.
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Affiliation(s)
- Jun Li
- State Key Laboratory of Plant Physiology and Biochemistry, China Agricultural University, Beijing 100094, China
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7
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Abstract
In this review we concentrate on guard cell metabolism and CO2 sensing. Although a matter of some controversy, it is generally accepted that the Calvin cycle plays a minor role in stomatal movements. Recent data emphasise the importance of guard cell starch degradation and of carbon import from the guard cell apoplast in promoting and maintaining stomatal opening. Chloroplast maltose and glucose transporters appear to be crucial to the export of carbon from both guard and mesophyll cells. The way guard cells sense CO2 remains an unresolved question. However, a better understanding of the cellular events downstream from CO2 sensing is emerging. We now recognise that there are common as well as unique steps in abscisic acid (ABA) and CO2 signalling pathways. For example, while ABA and CO2 both trigger increases in cytoplasmic free calcium, unlike ABA, CO2 does not promote a cytoplasmic pH change. Future advances in this area are likely to result from the increased use of techniques and resources, such as, reverse genetics, novel mutants, confocal imaging, and microarray analyses of the guard cell transcriptome.
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Affiliation(s)
- Alain Vavasseur
- CEA/Cadarache-DSV-DEVM, Laboratoire des Echanges Membranaires et Signalisation, UMR 6191 CNRS-CEA-Aix-Marseille II. 13108 St Paul Lez-Durance Cedex, France.
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8
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Yang SH, Berberich T, Sano H, Kusano T. Specific association of transcripts of tbzF and tbz17, tobacco genes encoding basic region leucine zipper-type transcriptional activators, with guard cells of senescing leaves and/or flowers. PLANT PHYSIOLOGY 2001; 127:23-32. [PMID: 11553731 PMCID: PMC117959 DOI: 10.1104/pp.127.1.23] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2000] [Revised: 03/19/2001] [Accepted: 05/18/2001] [Indexed: 05/20/2023]
Abstract
Induction by low temperature is a common feature of the lip19 subfamily members of the basic region leucine zipper gene family in plants. Here, we characterize two tobacco (Nicotiana tabacum) genes, tbzF and tbz17, belonging to the lip19 subfamily, whose gene products, TBZF and TBZ17, show 73% identity and are located in nuclei. They preferentially bind to DNA fragments spanning A-box/G-box and C-box/G-box hybrid motifs and show transactivation activity in cobombarded tobacco BY-2 cells, indicating they function as transcriptional activators. Transcripts of tbzF were detected at a high level in senescing leaves and flowers. In contrast, tbz17 transcripts could be shown to accumulate in aged leaves but not in flowers. In situ hybridization analysis revealed transcripts of tbzF and tbz17 to be predominantly located in guard cells and vascular tissues of senescing leaves. These results suggest that TBZF and TBZ17 are both involved in controlling gene transcription related to functions of guard cells in senescing leaves and that TBZF bifunctionally acts in floral development.
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Affiliation(s)
- S H Yang
- Research and Education Center for Genetic Information, Nara Institute of Science and Technology, Ikoma, Nara 630-0101, Japan
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9
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Webb AA, Larman MG, Montgomery LT, Taylor JE, Hetherington AM. The role of calcium in ABA-induced gene expression and stomatal movements. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2001; 26:351-62. [PMID: 11439123 DOI: 10.1046/j.1365-313x.2001.01032.x] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
There is much interest in the transduction pathways by which abscisic acid (ABA) regulates stomatal movements (ABA-turgor signalling) and by which this phytohormone regulates the pattern of gene expression in plant cells (ABA-nuclear signalling). A number of second messengers have been identified in both the ABA-turgor and ABA-nuclear signalling pathways. A major challenge is to understand the architecture of ABA-signalling pathways and to determine how the ABA signal is coupled to the appropriate response. We have investigated whether separate Ca2+-dependent and -independent ABA-signalling pathways are present in guard cells. Our data suggest that increases in [Ca2+]i are a common component of the guard cell ABA-turgor and ABA-nuclear signalling pathways. The effects of Ca2+ antagonists on ABA-induced stomatal closure and the ABA-responsive CDeT6-19 gene promoter suggest that Ca2+ is involved in both ABA-turgor signalling and ABA-nuclear signalling in guard cells. However, the sensitivity of these pathways to alterations in the external calcium concentration differ, suggesting that the ABA-nuclear and ABA-turgor signalling pathways are not completely convergent. Our data suggest that whilst Ca2+-independent signalling elements are present in the guard cell, they do not form a completely separate Ca2+-independent ABA-signalling pathway.
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Affiliation(s)
- A A Webb
- Department of Biological Sciences, Institute of Environmental and Natural Sciences, Lancaster University, Bailrigg, Lancaster LA1 4YQ, UK.
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10
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Wood NT, Haley A, Viry-Moussaïd M, Johnson CH, van der Luit AH, Trewavas AJ. The calcium rhythms of different cell types oscillate with different circadian phases. PLANT PHYSIOLOGY 2001; 125:787-96. [PMID: 11161036 PMCID: PMC64880 DOI: 10.1104/pp.125.2.787] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2000] [Revised: 08/22/2000] [Accepted: 10/02/2000] [Indexed: 05/17/2023]
Abstract
Transgenic tobacco (Nicotiana plumbaginifolia) seedlings containing the Ca(2+)-sensitive luminescent protein aequorin have been shown to exhibit circadian variations in cytosolic calcium. Concomitant measurements of cytosolic and nuclear calcium show that circadian variations in the cytoplasm are not expressed in the nucleus. To investigate whether all cells of transgenic seedlings contribute equally to circadian variations in cytosolic calcium, different promoters eliciting different expression patterns have been placed upstream of aequorin and used for transformation. The circadian peak occurred at different times in the three transgenic lines constructed. Luminescence imaging of these transgenic lines indicated that aequorin was differentially accumulated among the main tissues and cells of the seedlings and overcoat technology with applied epidermal strips indicated that the surface cell layers contribute the vast majority of luminescent light. We conclude that the Ca(2+) rhythmicities of cells and tissues oscillate with distinct differences in phase, that this might represent different underlying cellular control mechanisms and that these observations have significant implications for our understanding and study of Ca(2+) mediated signal transduction in plant cells.
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Affiliation(s)
- N T Wood
- Institute of Cell and Molecular Biology, Kings Buildings, Mayfield Road, University of Edinburgh, Edinburgh EH9 3JH, United Kingdom.
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11
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Menke U, Renault N, Mueller-Roeber B. StGCPRP, a potato gene strongly expressed in stomatal guard cells, defines a novel type of repetitive proline-rich proteins. PLANT PHYSIOLOGY 2000; 122:677-86. [PMID: 10712530 PMCID: PMC58902 DOI: 10.1104/pp.122.3.677] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/1999] [Accepted: 11/05/1999] [Indexed: 05/20/2023]
Abstract
Guard cells represent a highly differentiated cell type within the epidermis of plant leaves and stems. They respond to many endogenous and environmental signals and thereby modify the size of the stomatal pore they surround. We identified a novel gene that is highly expressed in guard cells of potato (Solanum tuberosum). It encodes a repetitive proline (Pro)-rich protein of 54 kD (491 amino acids) and was named StGCPRP (S. tuberosum guard cell Pro-rich protein). StGCPRP has a bipartite structure. The C-terminal part of StGCPRP contains a high percentage (46%) of Pro residues organized in distinct repetitive sequence motifs, whereas its extended N terminus is essentially free of Pros. StGCPRP represents the first member of a novel class of hybrid Pro-rich proteins that we designated NHyPRPs. In young but not in mature leaves, StGCPRP transcripts were also present at high levels in mesophyll cells (in addition to guard cells), indicating developmental regulation of StGCPRP gene expression. In addition, StGCPRP expression is regulated by environmental factors, as shown by a decrease in StGCPRP transcript levels under drought stress. Two proteins similar to StGCPRP were found to be encoded by the Arabidopsis genome, indicating that NHyPRPs are more widely distributed in higher plants.
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MESH Headings
- Amino Acid Sequence
- Cloning, Molecular
- DNA, Complementary/genetics
- DNA, Plant/genetics
- Gene Expression Regulation, Developmental
- Gene Expression Regulation, Plant
- Genes, Plant
- In Situ Hybridization
- Molecular Sequence Data
- Plant Proteins/chemistry
- Plant Proteins/genetics
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- RNA, Plant/genetics
- RNA, Plant/metabolism
- Repetitive Sequences, Amino Acid
- Solanum tuberosum/cytology
- Solanum tuberosum/genetics
- Solanum tuberosum/growth & development
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Affiliation(s)
- U Menke
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, D-14424 Potsdam/Golm, Germany
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12
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Busk PK, Borrell A, Kizis D, Pagès M. Abscisic acid perception and transduction. ACTA ACUST UNITED AC 1999. [DOI: 10.1016/s0167-7306(08)60502-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/09/2023]
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13
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Abstract
The plant hormone abscisic acid (ABA) plays a major role in seed maturation and germination, as well as in adaptation to abiotic environmental stresses. ABA promotes stomatal closure by rapidly altering ion fluxes in guard cells. Other ABA actions involve modifications of gene expression, and the analysis of ABA-responsive promoters has revealed a diversity of potential cis-acting regulatory elements. The nature of the ABA receptor(s) remains unknown. In contrast, combined biophysical, genetic, and molecular approaches have led to considerable progress in the characterization of more downstream signaling elements. In particular, substantial evidence points to the importance of reversible protein phosphorylation and modifications of cytosolic calcium levels and pH as intermediates in ABA signal transduction. Exciting advances are being made in reassembling individual components into minimal ABA signaling cascades at the single-cell level.
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Affiliation(s)
- Jeffrey Leung
- Institut des Sciences Vegetales, Unite Propre de Recherche 40, Centre National de la Recherche Scientifique, 1 Avenue de la Terrasse, 91190 Gif-sur-Yvette, France; e-mail:
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14
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Parra MM, del Pozo O, Luna R, Godoy JA, Pintor-Toro JA. Structure of the dehydrin tas14 gene of tomato and its developmental and environmental regulation in transgenic tobacco. PLANT MOLECULAR BIOLOGY 1996; 32:453-60. [PMID: 8980494 DOI: 10.1007/bf00019097] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
We have isolated a genomic clone encoding tomato TAS14, a dehydrin that accumulates in response to mannitol, NaCl or abscisic acid (ABA) treatment. A fragment of tas14 gene containing the region from -2591 to +162 fused to beta-glucuronidase gene drives ABA- and osmotic stress-induced GUS expression in transgenic tobacco. Histochemical analysis of salt-, mannitol- and ABA-treated plants showed GUS activity mainly localized to vascular tissues, outer cortex and adventitious root meristems, coinciding with the previously observed distribution of TAS14 protein in salt-stressed tomato plants. In addition, GUS activity was also observed in guard cells, trichomes and leaf axils. Developmentally regulated gus expression was studied in unstressed plants and found to occur not only in embryos, but also in flowers and pollen. Tas14 expression in floral organs was confirmed by northern blots of tomato flowers.
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MESH Headings
- Abscisic Acid/pharmacology
- Cloning, Molecular
- Gene Expression Regulation, Plant/drug effects
- Gene Expression Regulation, Plant/physiology
- Genes, Reporter/genetics
- Glucuronidase/genetics
- Solanum lycopersicum/genetics
- Solanum lycopersicum/growth & development
- Mannitol/pharmacology
- Molecular Sequence Data
- Osmotic Pressure
- Plant Proteins/genetics
- Plants, Genetically Modified
- Plants, Toxic
- Promoter Regions, Genetic/genetics
- RNA, Messenger/analysis
- RNA, Plant/analysis
- Sequence Analysis, DNA
- Sodium Chloride/pharmacology
- Nicotiana/genetics
- Nicotiana/growth & development
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Affiliation(s)
- M M Parra
- Instituto de Recursos Naturales y Agrobiología, C.S.I.C., Sevilla, Spain
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15
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Abstract
Molecular studies of drought stress in plants use a variety of strategies and include different species subjected to a wide range of water deficits. Initial research has by necessity been largely descriptive, and relevant genes have been identified either by reference to physiological evidence or by differential screening. A large number of genes with a potential role in drought tolerance have been described, and major themes in the molecular response have been established. Particular areas of importance are sugar metabolism and late-embryogenesis-abundant (LEA) proteins. Studies have begun to examine mechanisms that control the gene expression, and putative regulatory pathways have been established. Recent attempts to understand gene function have utilized transgenic plants. These efforts are of clear agronomic importance.
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Affiliation(s)
- J. Ingram
- Max-Planck-Institut fur Zuchtungsforschung, Carl-von-Linne-Weg 10 Koln, 50829 Germany
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16
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Abstract
The plant hormone abscisic acid (ABA) regulates the development and germination of seeds, as well as the adaptation of vegetative tissues to conditions of environmental stress. During the past year, considerable insights have been gained into the molecular nature of the complex signaling network that mediates the actions of ABA. Biophysical studies indicate that at least some of the effects of ABA in stomatal guard cells involve intracellular receptors. Also, increasing evidence supports the view that guard cells contain redundant ABA transduction pathways, and that cytoplasmic Ca2+ acts as a second messenger in at least one of these pathways. Finally, mutational analysis in Arabidopsis indicates that the multiple effects of ABA at the whole plant level are mediated by overlapping branches of a highly ramified signaling network. Two Arabidopsis loci that determine ABA sensitivity have already been cloned and found to encode a protein phosphatase and a transcriptional activator.
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Affiliation(s)
- J Giraudat
- Institut des Sciences Végétales, Centre National de la Recherche Scientifique, Gif-sur-Yvette, France
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