1
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Hõrak H, Fountain L, Dunn JA, Landymore J, Gray JE. Leaf temperature responses to ABA and dead bacteria in wheat and Arabidopsis. PLANT SIGNALING & BEHAVIOR 2021; 16:1899471. [PMID: 33704000 PMCID: PMC8078522 DOI: 10.1080/15592324.2021.1899471] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Revised: 02/26/2021] [Accepted: 03/02/2021] [Indexed: 06/12/2023]
Abstract
Stomatal densities, aperture openness and their responsiveness to environmental change determine plant water loss and regulate entry of pathogens. Stomatal responsiveness is usually assessed on restricted areas of leaves or isolated epidermal peels floated in solution. Analyzing these responses in the whole plant context could give valuable additional information, for example on the role of mesophyll in stomatal responses. We analyzed stomatal responses to the phytohormone abscisic acid (ABA) and pathogenic elicitors in intact plants by dynamic measurement of leaf temperature. We tested whether ABA-induced stomatal closure in wheat requires external nitrate and whether bacterial elicitor-induced stomatal closure can be detected by dynamic thermal imaging in intact Arabidopsis. We found that wheat was hypersensitive to all applied treatments, as even mock-treated leaves showed a strong increase in leaf temperature. Nevertheless, ABA activated stomatal closure in wheat independent of exogenous nitrate. Pathogenic elicitors triggered a fast and transient increase in leaf temperature in intact Arabidopsis, indicating short-term stomatal closure. The data suggest that the dynamics of pathogen-induced stomatal closure is different in whole plants compared to epidermal peels, where elicitor-induced stomatal closure persists longer. We propose that dynamic thermal imaging could be applied to address the effect of pathogenic elicitors on stomatal behavior in whole plants to complement detached sample assays and gain a better understanding of stomatal immunity.
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Affiliation(s)
- Hanna Hõrak
- Institute of Technology, University of Tartu, Tartu, Estonia
| | - Luke Fountain
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, UK
| | - Jessica A. Dunn
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, UK
| | - Joanna Landymore
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, UK
| | - Julie E. Gray
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, UK
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2
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Hõrak H, Fountain L, Dunn JA, Landymore J, Gray JE. Dynamic thermal imaging confirms local but not fast systemic ABA responses. PLANT, CELL & ENVIRONMENT 2021; 44:885-899. [PMID: 33295045 DOI: 10.1111/pce.13973] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2020] [Revised: 11/30/2020] [Accepted: 12/04/2020] [Indexed: 06/12/2023]
Abstract
Abscisic acid (ABA) signals regulating stomatal aperture and water loss are usually studied in detached leaves or isolated epidermal peels and at infrequent timepoints. Measuring stomatal ABA responses in attached leaves across a time course enables the study of stomatal behaviour in the physiological context of the plant. Infrared thermal imaging is often used to characterize steady-state stomatal conductance via comparisons of leaf surface temperature but is rarely used to capture stomatal responses over time or across different leaf surfaces. We used dynamic thermal imaging as a robust, but sensitive, tool to observe stomatal ABA responses in a whole plant context. We detected stomatal responses to low levels of ABA in both monocots and dicots and identified differences between the responses of different leaves. Using whole plant thermal imaging, stomata did not always behave as described previously for detached samples: in Arabidopsis, we found no evidence for fast systemic ABA-induced stomatal closure, and in barley, we observed no requirement for exogenous nitrate during ABA-induced stomatal closure. Thus, we recommend dynamic thermal imaging as a useful approach to complement detached sample assays for the study of local and systemic stomatal responses and molecular mechanisms underlying stomatal responses to ABA in the whole plant context.
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Affiliation(s)
- Hanna Hõrak
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield, S10 2TN, UK
- Institute of Technology, University of Tartu, Nooruse 1, Tartu, 50411, Estonia
| | - Luke Fountain
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield, S10 2TN, UK
| | - Jessica A Dunn
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield, S10 2TN, UK
| | - Joanna Landymore
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield, S10 2TN, UK
| | - Julie E Gray
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield, S10 2TN, UK
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3
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Vicente J, Mendiondo GM, Pauwels J, Pastor V, Izquierdo Y, Naumann C, Movahedi M, Rooney D, Gibbs DJ, Smart K, Bachmair A, Gray JE, Dissmeyer N, Castresana C, Ray RV, Gevaert K, Holdsworth MJ. Distinct branches of the N-end rule pathway modulate the plant immune response. THE NEW PHYTOLOGIST 2019; 221:988-1000. [PMID: 30117535 DOI: 10.1111/nph.15387] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Accepted: 07/11/2018] [Indexed: 05/24/2023]
Abstract
The N-end rule pathway is a highly conserved constituent of the ubiquitin proteasome system, yet little is known about its biological roles. Here we explored the role of the N-end rule pathway in the plant immune response. We investigated the genetic influences of components of the pathway and known protein substrates on physiological, biochemical and metabolic responses to pathogen infection. We show that the glutamine (Gln) deamidation and cysteine (Cys) oxidation branches are both components of the plant immune system, through the E3 ligase PROTEOLYSIS (PRT)6. In Arabidopsis thaliana Gln-specific amino-terminal (Nt)-amidase (NTAQ1) controls the expression of specific defence-response genes, activates the synthesis pathway for the phytoalexin camalexin and influences basal resistance to the hemibiotroph pathogen Pseudomonas syringae pv tomato (Pst). The Nt-Cys ETHYLENE RESPONSE FACTOR VII transcription factor substrates enhance pathogen-induced stomatal closure. Transgenic barley with reduced HvPRT6 expression showed enhanced resistance to Ps. japonica and Blumeria graminis f. sp. hordei, indicating a conserved role of the pathway. We propose that that separate branches of the N-end rule pathway act as distinct components of the plant immune response in flowering plants.
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Affiliation(s)
- Jorge Vicente
- School of Biosciences, University of Nottingham, Nottingham, LE12 5RD, UK
| | | | - Jarne Pauwels
- VIB-UGent Center for Medical Biotechnology, Albert Baertsoenkaai 3, B-9000, Ghent, Belgium
- Department of Biochemistry, Ghent University, Albert Baertsoenkaai 3, B-9000, Ghent, Belgium
| | - Victoria Pastor
- Área de Fisiología Vegetal, Departamento de Ciencias Agrarias y del Medio Natural, Universitat Jaume I, Castellón, E-12071, Spain
| | - Yovanny Izquierdo
- Centro National de Biotecnología CSIC, C/Darwin, 3, Campus of Cantoblanco, E-28049, Madrid, Spain
| | - Christin Naumann
- Leibniz Institute of Plant Biochemistry (IPB), Weinberg 3, D-06120, Halle (Saale), Germany
- Science Campus Halle - Plant-Based Bioeconomy, 06120 Halle (Saale), Germany
| | - Mahsa Movahedi
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, S10 2TN, UK
| | - Daniel Rooney
- School of Biosciences, University of Nottingham, Nottingham, LE12 5RD, UK
| | - Daniel J Gibbs
- School of Biosciences, University of Nottingham, Nottingham, LE12 5RD, UK
| | - Katherine Smart
- SABMiller Plc, SABMiller House, Church Street West, Woking, GU21 6HS, UK
| | - Andreas Bachmair
- Department of Biochemistry and Cell Biology, Max F. Perutz Laboratories, University of Vienna, Dr. Bohr Gasse 9, Vienna, A-1030, Austria
| | - Julie E Gray
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, S10 2TN, UK
| | - Nico Dissmeyer
- Leibniz Institute of Plant Biochemistry (IPB), Weinberg 3, D-06120, Halle (Saale), Germany
- Science Campus Halle - Plant-Based Bioeconomy, 06120 Halle (Saale), Germany
| | - Carmen Castresana
- Centro National de Biotecnología CSIC, C/Darwin, 3, Campus of Cantoblanco, E-28049, Madrid, Spain
| | - Rumiana V Ray
- School of Biosciences, University of Nottingham, Nottingham, LE12 5RD, UK
| | - Kris Gevaert
- VIB-UGent Center for Medical Biotechnology, Albert Baertsoenkaai 3, B-9000, Ghent, Belgium
- Department of Biochemistry, Ghent University, Albert Baertsoenkaai 3, B-9000, Ghent, Belgium
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4
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Geilfus CM, Ludwig-Müller J, Bárdos G, Zörb C. Early response to salt ions in maize (Zea mays L.). JOURNAL OF PLANT PHYSIOLOGY 2018; 220:173-180. [PMID: 29195231 DOI: 10.1016/j.jplph.2017.11.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2017] [Revised: 11/06/2017] [Accepted: 11/20/2017] [Indexed: 05/26/2023]
Abstract
Abscisic acid (ABA) regulates leaf growth and transpiration rate of plants exposed to salt stress. Despite the known fact that cell dehydration is instrumental for the modulation of ABA concentrations when NaCl is high in the external environment, it was never tested as to whether sodium (Na) or chlorine (Cl) also modulate ABA concentrations. To answer this question, a hydroponic study on maize (Zea mays) was established, by exposing plants to 50mM of sodium glucosamide or glucosamine chloride. The effect of both ions on ABA was investigated in an early stage before (i) the salt ions accumulated to toxic tissue concentrations and before (ii) cells dehydrated. This allowed studying early responses to Na and Cl separately, well before plants were stressed by these ions. Gas chromatography-mass spectrometry analysis was used to quantify ABA concentrations in roots and in leaves after a period of 2h after ion application. The transcript abundance of the key regulatory enzyme of the biosynthesis of ABA in maize, the 9-cis-epoxycarotenoid dioxygenase gene viviparous 14, was quantified via real-time quantitative-reverse-transcriptase-polymerase-chain-reaction. The results reveal that Cl and Na induce the increase of leaf tissue ABA concentrations at two hours after plants were exposed to 50mM of the ions. Surprisingly, this effect was more pronounced in response to the Cl component. The increase in the guard-cell regulating ABA concentration correlated with a reduced transpiration. Mainly because of this result we suggest that the early accumulation of ABA is useful in maintaining cell turgor.
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Affiliation(s)
- Christoph-Martin Geilfus
- Controlled Environment Horticulture, Faculty of Life Sciences, Albrecht Daniel Thaer-Institute of Agricultural and Horticultural Sciences, Humboldt-University of Berlin, Lentzeallee, 14195, Berlin, Germany
| | - Jutta Ludwig-Müller
- Institut für Botanik, Technische Universität Dresden, Zellescher Weg 20b, D-01062 Dresden, Germany
| | - Gyöngyi Bárdos
- Institute of Crop Science, Quality of Plant Products, University of Hohenheim, Emil-Wolff-Straße 25, 70599, Stuttgart, Germany
| | - Christian Zörb
- Institute of Crop Science, Quality of Plant Products, University of Hohenheim, Emil-Wolff-Straße 25, 70599, Stuttgart, Germany.
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5
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Shen L, Sun P, Bonnell VC, Edwards KJ, Hetherington AM, McAinsh MR, Roberts MR. Measuring stress signaling responses of stomata in isolated epidermis of graminaceous species. FRONTIERS IN PLANT SCIENCE 2015; 6:533. [PMID: 26217375 PMCID: PMC4499840 DOI: 10.3389/fpls.2015.00533] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Accepted: 06/29/2015] [Indexed: 05/07/2023]
Abstract
Our current understanding of guard cell signaling pathways is derived from studies in a small number of model species. The ability to study stomatal responses in isolated epidermis has been an important factor in elucidating the mechanisms by which the stomata of these species respond to environmental stresses. However, such approaches have rarely been applied to study guard cell signaling in the stomata of graminaceous species (including many of the world's major crops), in which the guard cells have a markedly different morphology to those in other plants. Our understanding of guard cell signaling in these important species is therefore much more limited. Here, we describe a procedure for the isolation of abaxial epidermal peels from barley, wheat and Brachypodium distachyon. We show that isolated epidermis from these species contains viable guard cells that exhibit typical responses to abscisic acid (ABA) and CO2, as determined by measurements of stomatal apertures. We use the epidermal peel assay technique to investigate in more detail interactions between different environmental factors in barley guard cells, and demonstrate that stomatal closure in response to external CO2 is inhibited at higher temperatures, whilst sensitivity to ABA is enhanced at 30°C compared to 20 and 40°C.
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Affiliation(s)
- Lei Shen
- Lancaster Environment Centre, Lancaster University, Lancaster, UK
| | - Peng Sun
- School of Biological Sciences, University of Bristol, Bristol, UK
| | | | - Keith J. Edwards
- School of Biological Sciences, University of Bristol, Bristol, UK
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6
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Gibbs DJ, Md Isa N, Movahedi M, Lozano-Juste J, Mendiondo GM, Berckhan S, Marín-de la Rosa N, Vicente Conde J, Sousa Correia C, Pearce SP, Bassel GW, Hamali B, Talloji P, Tomé DFA, Coego A, Beynon J, Alabadí D, Bachmair A, León J, Gray JE, Theodoulou FL, Holdsworth MJ. Nitric oxide sensing in plants is mediated by proteolytic control of group VII ERF transcription factors. Mol Cell 2014; 53:369-79. [PMID: 24462115 PMCID: PMC3969242 DOI: 10.1016/j.molcel.2013.12.020] [Citation(s) in RCA: 250] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2013] [Revised: 11/14/2013] [Accepted: 12/13/2013] [Indexed: 11/28/2022]
Abstract
Nitric oxide (NO) is an important signaling compound in prokaryotes and eukaryotes. In plants, NO regulates critical developmental transitions and stress responses. Here, we identify a mechanism for NO sensing that coordinates responses throughout development based on targeted degradation of plant-specific transcriptional regulators, the group VII ethylene response factors (ERFs). We show that the N-end rule pathway of targeted proteolysis targets these proteins for destruction in the presence of NO, and we establish them as critical regulators of diverse NO-regulated processes, including seed germination, stomatal closure, and hypocotyl elongation. Furthermore, we define the molecular mechanism for NO control of germination and crosstalk with abscisic acid (ABA) signaling through ERF-regulated expression of ABSCISIC ACID INSENSITIVE5 (ABI5). Our work demonstrates how NO sensing is integrated across multiple physiological processes by direct modulation of transcription factor stability and identifies group VII ERFs as central hubs for the perception of gaseous signals in plants.
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Affiliation(s)
- Daniel J Gibbs
- Division of Plant and Crop Sciences, School of Biosciences, University of Nottingham, Loughborough LE12 5RD, UK
| | - Nurulhikma Md Isa
- Division of Plant and Crop Sciences, School of Biosciences, University of Nottingham, Loughborough LE12 5RD, UK
| | - Mahsa Movahedi
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, UK
| | - Jorge Lozano-Juste
- Instituto de Biología Molecular y Celular de Plantas, Consejo Superior de Investigaciones Científicas-Universidad Politécnica de Valencia, Ciudad Politécnica de la Innovación, 46022 Valencia, Spain
| | - Guillermina M Mendiondo
- Division of Plant and Crop Sciences, School of Biosciences, University of Nottingham, Loughborough LE12 5RD, UK
| | - Sophie Berckhan
- Division of Plant and Crop Sciences, School of Biosciences, University of Nottingham, Loughborough LE12 5RD, UK
| | - Nora Marín-de la Rosa
- Instituto de Biología Molecular y Celular de Plantas, Consejo Superior de Investigaciones Científicas-Universidad Politécnica de Valencia, Ciudad Politécnica de la Innovación, 46022 Valencia, Spain
| | - Jorge Vicente Conde
- Division of Plant and Crop Sciences, School of Biosciences, University of Nottingham, Loughborough LE12 5RD, UK
| | - Cristina Sousa Correia
- Division of Plant and Crop Sciences, School of Biosciences, University of Nottingham, Loughborough LE12 5RD, UK
| | - Simon P Pearce
- Division of Plant and Crop Sciences, School of Biosciences, University of Nottingham, Loughborough LE12 5RD, UK
| | - George W Bassel
- Division of Plant and Crop Sciences, School of Biosciences, University of Nottingham, Loughborough LE12 5RD, UK
| | - Bulut Hamali
- Department of Biochemistry and Cell Biology, Max F. Perutz Laboratories, University of Vienna, Dr. Bohr Gasse 9, Vienna 1030, Austria
| | - Prabhavathi Talloji
- Department of Biochemistry and Cell Biology, Max F. Perutz Laboratories, University of Vienna, Dr. Bohr Gasse 9, Vienna 1030, Austria
| | - Daniel F A Tomé
- School of Life Sciences, University of Warwick, Coventry CV4 7AL, UK
| | - Alberto Coego
- Instituto de Biología Molecular y Celular de Plantas, Consejo Superior de Investigaciones Científicas-Universidad Politécnica de Valencia, Ciudad Politécnica de la Innovación, 46022 Valencia, Spain
| | - Jim Beynon
- School of Life Sciences, University of Warwick, Coventry CV4 7AL, UK
| | - David Alabadí
- Instituto de Biología Molecular y Celular de Plantas, Consejo Superior de Investigaciones Científicas-Universidad Politécnica de Valencia, Ciudad Politécnica de la Innovación, 46022 Valencia, Spain
| | - Andreas Bachmair
- Department of Biochemistry and Cell Biology, Max F. Perutz Laboratories, University of Vienna, Dr. Bohr Gasse 9, Vienna 1030, Austria
| | - José León
- Instituto de Biología Molecular y Celular de Plantas, Consejo Superior de Investigaciones Científicas-Universidad Politécnica de Valencia, Ciudad Politécnica de la Innovación, 46022 Valencia, Spain
| | - Julie E Gray
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, UK
| | - Frederica L Theodoulou
- Biological Chemistry and Crop Protection Department, Rothamsted Research, Harpenden AL5 2JQ, UK
| | - Michael J Holdsworth
- Division of Plant and Crop Sciences, School of Biosciences, University of Nottingham, Loughborough LE12 5RD, UK.
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7
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Brodribb TJ, McAdam SAM. Unique responsiveness of angiosperm stomata to elevated CO2 explained by calcium signalling. PLoS One 2013; 8:e82057. [PMID: 24278470 PMCID: PMC3835710 DOI: 10.1371/journal.pone.0082057] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2013] [Accepted: 10/29/2013] [Indexed: 11/24/2022] Open
Abstract
Angiosperm and conifer tree species respond differently when exposed to elevated CO2, with angiosperms found to dynamically reduce water loss while conifers appear insensitive. Such distinct responses are likely to affect competition between these tree groups as atmospheric CO2 concentration rises. Seeking the mechanism behind this globally important phenomenon we targeted the Ca(2+)-dependent signalling pathway, a mediator of stomatal closure in response to elevated CO2, as a possible explanation for the differentiation of stomatal behaviours. Sampling across the diversity of vascular plants including lycophytes, ferns, gymnosperms and angiosperms we show that only angiosperms possess the stomatal behaviour and prerequisite genetic coding, linked to Ca(2+)-dependent stomatal signalling. We conclude that the evolution of Ca(2+)-dependent stomatal signalling gives angiosperms adaptive benefits in terms of highly efficient water use, but that stomatal sensitivity to high CO2 may penalise angiosperm productivity relative to other plant groups in the current era of soaring atmospheric CO2.
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Affiliation(s)
- Timothy J. Brodribb
- School of Plant Science, University of Tasmania, Hobart, Tasmania, Australia
| | - Scott A. M. McAdam
- School of Plant Science, University of Tasmania, Hobart, Tasmania, Australia
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8
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Laanemets K, Brandt B, Li J, Merilo E, Wang YF, Keshwani MM, Taylor SS, Kollist H, Schroeder JI. Calcium-dependent and -independent stomatal signaling network and compensatory feedback control of stomatal opening via Ca2+ sensitivity priming. PLANT PHYSIOLOGY 2013; 163:504-13. [PMID: 23766366 PMCID: PMC3793032 DOI: 10.1104/pp.113.220343] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Guard cells use compensatory feedback controls to adapt to conditions that produce excessively open stomata.
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9
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Abstract
A range of techniques have been used to measure the concentration of cytosolic-free Ca(2+) ([Ca(2+)](cyt)) in plant cells. Fluorescent Ca(2+)-sensitive indicators have been used extensively to measure plant [Ca(2+)](cyt) and a number of techniques are available for loading these into plant cells. Here we describe a method for measuring [Ca(2+)](cyt) in the guard cells of the model plant species Commelina communis by ratio photometry and imaging techniques using the ratiometric fluorescent Ca(2+)-sensitive indicator fura-2.
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Affiliation(s)
- Martin R McAinsh
- Lancaster Environment Centre, Lancaster University, Lancaster, UK.
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10
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Chen ZH, Hills A, Bätz U, Amtmann A, Lew VL, Blatt MR. Systems dynamic modeling of the stomatal guard cell predicts emergent behaviors in transport, signaling, and volume control. PLANT PHYSIOLOGY 2012; 159:1235-51. [PMID: 22635112 PMCID: PMC3404696 DOI: 10.1104/pp.112.197350] [Citation(s) in RCA: 115] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2012] [Accepted: 05/23/2012] [Indexed: 05/17/2023]
Abstract
The dynamics of stomatal movements and their consequences for photosynthesis and transpirational water loss have long been incorporated into mathematical models, but none have been developed from the bottom up that are widely applicable in predicting stomatal behavior at a cellular level. We previously established a systems dynamic model incorporating explicitly the wealth of biophysical and kinetic knowledge available for guard cell transport, signaling, and homeostasis. Here we describe the behavior of the model in response to experimentally documented changes in primary pump activities and malate (Mal) synthesis imposed over a diurnal cycle. We show that the model successfully recapitulates the cyclic variations in H⁺, K⁺, Cl⁻, and Mal concentrations in the cytosol and vacuole known for guard cells. It also yields a number of unexpected and counterintuitive outputs. Among these, we report a diurnal elevation in cytosolic-free Ca²⁺ concentration and an exchange of vacuolar Cl⁻ with Mal, both of which find substantiation in the literature but had previously been suggested to require additional and complex levels of regulation. These findings highlight the true predictive power of the OnGuard model in providing a framework for systems analysis of stomatal guard cells, and they demonstrate the utility of the OnGuard software and HoTSig library in exploring fundamental problems in cellular physiology and homeostasis.
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Affiliation(s)
| | | | | | - Anna Amtmann
- Laboratory of Plant Physiology and Biophysics, University of Glasgow, Glasgow G12 8QQ, United Kingdom (Z.-H.C., A.H., U.B., A.A., M.R.B.); and Physiological Laboratory, University of Cambridge, Cambridge CB2 3EG, United Kingdom (V.L.L.)
| | - Virgilio L. Lew
- Laboratory of Plant Physiology and Biophysics, University of Glasgow, Glasgow G12 8QQ, United Kingdom (Z.-H.C., A.H., U.B., A.A., M.R.B.); and Physiological Laboratory, University of Cambridge, Cambridge CB2 3EG, United Kingdom (V.L.L.)
| | - Michael R. Blatt
- Laboratory of Plant Physiology and Biophysics, University of Glasgow, Glasgow G12 8QQ, United Kingdom (Z.-H.C., A.H., U.B., A.A., M.R.B.); and Physiological Laboratory, University of Cambridge, Cambridge CB2 3EG, United Kingdom (V.L.L.)
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11
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Bothwell JHF, Brownlee C, Hetherington AM, Ng CKY, Wheeler GL, McAinsh MR. Biolistic delivery of Ca2+ dyes into plant and algal cells. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2006; 46:327-35. [PMID: 16623894 DOI: 10.1111/j.1365-313x.2006.02687.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
In eukaryotes, changes in cytosolic Ca2+ concentrations ([Ca2+]cyt) are associated with a number of environmental and developmental stimuli. However, measuring [Ca2+]cyt changes in single plant or algal cells is often problematic. Although a wide range of Ca2+-sensitive fluorescent dyes is available, they are often difficult to introduce into plant cells. Micro-injection is the most robust method for dye loading, but is time-consuming, technically demanding, and unsuitable in many cell types. To overcome these problems, we have adapted biolistic techniques to load Ca2+-sensitive dyes into guard cells of the flowering plant, Commelina communis, cells of the green alga Chlamydomonas reinhardtii, and zygotes of the brown alga, Fucus serratus. Using this approach, we have been able to monitor [Ca2+]cyt changes in response to various stimuli, including a novel [Ca2+]cyt response in C. reinhardtii. The method allows the use of free acid and dextran-conjugated dyes. Biolistic loading of differentiated plant cells is easier, quicker, and more widely applicable than micro-injection, and should broaden the study of plant signal transduction.
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Affiliation(s)
- John H F Bothwell
- Marine Biological Association of the UK, The Laboratory, Citadel Hill, Plymouth PL1 2PB, UK
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12
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Delk NA, Johnson KA, Chowdhury NI, Braam J. CML24, regulated in expression by diverse stimuli, encodes a potential Ca2+ sensor that functions in responses to abscisic acid, daylength, and ion stress. PLANT PHYSIOLOGY 2005; 139:240-53. [PMID: 16113225 PMCID: PMC1203374 DOI: 10.1104/pp.105.062612] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2005] [Revised: 05/10/2005] [Accepted: 05/15/2005] [Indexed: 05/04/2023]
Abstract
Changes in intracellular calcium (Ca(2+)) levels serve to signal responses to diverse stimuli. Ca(2+) signals are likely perceived through proteins that bind Ca(2+), undergo conformation changes following Ca(2+) binding, and interact with target proteins. The 50-member calmodulin-like (CML) Arabidopsis (Arabidopsis thaliana) family encodes proteins containing the predicted Ca(2+)-binding EF-hand motif. The functions of virtually all these proteins are unknown. CML24, also known as TCH2, shares over 40% amino acid sequence identity with calmodulin, has four EF hands, and undergoes Ca(2+)-dependent changes in hydrophobic interaction chromatography and migration rate through denaturing gel electrophoresis, indicating that CML24 binds Ca(2+) and, as a consequence, undergoes conformational changes. CML24 expression occurs in all major organs, and transcript levels are increased from 2- to 15-fold in plants subjected to touch, darkness, heat, cold, hydrogen peroxide, abscisic acid (ABA), and indole-3-acetic acid. However, CML24 protein accumulation changes were not detectable. The putative CML24 regulatory region confers reporter expression at sites of predicted mechanical stress; in regions undergoing growth; in vascular tissues and various floral organs; and in stomata, trichomes, and hydathodes. CML24-underexpressing transgenics are resistant to ABA inhibition of germination and seedling growth, are defective in long-day induction of flowering, and have enhanced tolerance to CoCl(2), molybdic acid, ZnSO(4), and MgCl(2). MgCl(2) tolerance is not due to reduced uptake or to elevated Ca(2+) accumulation. Together, these data present evidence that CML24, a gene expressed in diverse organs and responsive to diverse stimuli, encodes a potential Ca(2+) sensor that may function to enable responses to ABA, daylength, and presence of various salts.
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Affiliation(s)
- Nikkí A Delk
- Department of Biochemistry and Cell Biology, Rice University, Houston, Texas 77005-1892, USA
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13
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Iwai S, Shimomura N, Nakashima A, Etoh T. New Fava Bean Guard Cell Signaling Mutant Impaired in ABA-Induced Stomatal Closure. ACTA ACUST UNITED AC 2003; 44:909-13. [PMID: 14519772 DOI: 10.1093/pcp/pcg116] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
We isolated a mutant from Vicia faba L. cv. House Ryousai. It wilts easily under strong light and high temperature conditions, suggesting that its stomatal movement may be disturbed. We determined responses of mutant guard cells to some environmental stimuli. Mutant guard cells demonstrated an impaired ability to respond to ABA in 0.1 mM CaCl(2) and stomata did not close in the presence of up to 1 mM ABA, whereas wild-type stomata closed when exposed to 10 micro M ABA. Elevating external Ca(2+) caused a similar degree of stomatal closure in the wild type and the mutant. A high concentration of CO(2) (700 micro l liter(-1)) induced stomatal closure in the wild type, but not in the mutant. On the basis of these results, we propose the working hypothesis that the mutation occurs in the region downstream of CO(2) and ABA sensing and in the region upstream of Ca(2+) elevation. The mutant is named fia (fava bean impaired in ABA-induced stomatal closure).
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Affiliation(s)
- Sumio Iwai
- Faculty of Agriculture, Kagoshima University, Kohrimoto, Kagoshima, 890-0065 Japan.
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Ng CKY, Mcainsh MR, Gray JE, Hunt L, Leckie CP, Mills L, Hetherington AM. Calcium-based signalling systems in guard cells. THE NEW PHYTOLOGIST 2001; 151:109-120. [PMID: 33873375 DOI: 10.1046/j.1469-8137.2001.00152.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Calcium is a ubiquitous intracellular signal responsible for controlling numerous cellular processes in both plants and animals. As an example, Ca2+ has been shown to be a second messenger in the signal transduction pathways by which stomatal guard cells respond to external stimuli. Regulated increases in the cytosolic concentration of free calcium ions ([Ca2+ ]cyt ) in guard cells have been observed to be a common intermediate in many of the pathways leading to either opening or closing of the stomatal pore. This observation has prompted investigations into how specificity is encoded in the Ca2+ signal. It has been suggested that the key to generating stimulus-specific calcium signatures lies in the ability to access differentially the cellular machinery controlling calcium influx and release from intracellular stores. Several important components of the calcium-based signalling pathways have been identified in guard cells including cADPR, phospholipase C-InsP3 , InsP6 and H2 O2 . These data suggest that the pathways for intracellular mobilization of Ca2+ are evolutionarily conserved between plants and animals. ABBREVIATIONS: ABA, abscisic acid; [Ca2+ ]cyt , cytosolic free calcium concentration; [Ca2+ ]ext , external calcium concentration; IK,in ; inward-rectifying K+ currents; InsP3 , inositol-1,4,5-trisphosphate; InsP6 , inositol hexakisphosphate; PLC, phospholipase C; PLD, phospholipase D; PA, phosphatidic acid; H2 O2 , hydrogen peroxide; AAPK, ABA-activated serine-threonine protein kinase; cADPR, cyclic adenosine 5'-diphosphoribose; U73122, 1-(6-{[17â-3-methoxyestra-1,3,5(10)-trien-17-yl]amino}hexyl)-1H-pyrrole-2, 5-dione; RyR; ryanodine receptor; CICR; calcium-induced calcium-release; ICa , inward calcium current.
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Affiliation(s)
- CarL K-Y Ng
- Department of Biological Sciences, Institute of Environmental and Natural Sciences, Lancaster University, Bailrigg, Lancaster, LA1 4YQ, UK
| | - Martin R Mcainsh
- Department of Biological Sciences, Institute of Environmental and Natural Sciences, Lancaster University, Bailrigg, Lancaster, LA1 4YQ, UK
| | - Julie E Gray
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, S10 2UH, UK
| | - LeE Hunt
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, S10 2UH, UK
| | - Calum P Leckie
- Department of Physiological Sciences, The Medical School, University of Newcastle upon Tyne, NE2 4HH, UK
| | - Lewis Mills
- Department of Biological Sciences, Institute of Environmental and Natural Sciences, Lancaster University, Bailrigg, Lancaster, LA1 4YQ, UK
| | - Alistair M Hetherington
- Department of Biological Sciences, Institute of Environmental and Natural Sciences, Lancaster University, Bailrigg, Lancaster, LA1 4YQ, UK
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15
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Wood NT, Allan AC, Haley A, Viry-Moussaïd M, Trewavas AJ. The characterization of differential calcium signalling in tobacco guard cells. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2000; 24:335-44. [PMID: 11069707 DOI: 10.1046/j.1365-313x.2000.00881.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Two novel approaches for the study of Ca2+-mediated signal transduction in stomatal guard cells are described. Stimulus-induced changes in guard-cell cytosolic Ca2+ ([Ca2+]cyt) were monitored using viable stomata in epidermal strips of a transgenic line of Nicotiana plumbaginifolia expressing aequorin (the proteinous luminescent reporter of Ca2+) and in a new transgenic line in which aequorin expression was targeted specifically to the guard cells. The results indicated that abscisic acid (ABA)-induced stomatal closure was accompanied by increases in [Ca2+]cyt in epidermal strips. In addition to ABA, mechanical and low-temperature signals directly affected stomatal behaviour, promoting rapid closure. Elevations of guard-cell [Ca2+]cyt play a key role in the transduction of all three stimuli. However, there were striking differences in the magnitude and kinetics of the three responses. Studies using Ca2+ channel blockers and the Ca2+ chelator EGTA further suggested that mechanical and ABA signals primarily mobilize Ca2+ from intracellular store(s), whereas the influx of extracellular Ca2+ is a key component in the transduction of low-temperature signals. These results illustrate an aspect of Ca2+ signalling whereby the specificity of the response is encoded by different spatial or kinetic Ca2+ elevations.
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Affiliation(s)
- N T Wood
- Institute of Cell and Molecular Biology, University of Edinburgh, Mayfield Road, Edinburgh EH9 3JH, UK
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16
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Pei ZM, Murata Y, Benning G, Thomine S, Klüsener B, Allen GJ, Grill E, Schroeder JI. Calcium channels activated by hydrogen peroxide mediate abscisic acid signalling in guard cells. Nature 2000; 406:731-4. [PMID: 10963598 DOI: 10.1038/35021067] [Citation(s) in RCA: 1262] [Impact Index Per Article: 52.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Drought is a major threat to agricultural production. Plants synthesize the hormone abscisic acid (ABA) in response to drought, triggering a signalling cascade in guard cells that results in stomatal closure, thus reducing water loss. ABA triggers an increase in cytosolic calcium in guard cells ([Ca2+]cyt) that has been proposed to include Ca2+ influx across the plasma membrane. However, direct recordings of Ca2+ currents have been limited and the upstream activation mechanisms of plasma membrane Ca2+ channels remain unknown. Here we report activation of Ca2+-permeable channels in the plasma membrane of Arabidopsis guard cells by hydrogen peroxide. The H2O2-activated Ca2+ channels mediate both influx of Ca2+ in protoplasts and increases in [Ca2+]cyt in intact guard cells. ABA induces the production of H2O2 in guard cells. If H2O2 production is blocked, ABA-induced closure of stomata is inhibited. Moreover, activation of Ca2+ channels by H2O2 and ABA- and H2O2-induced stomatal closing are disrupted in the recessive ABA-insensitive mutant gca2. These data indicate that ABA-induced H2O2 production and the H2O2-activated Ca2+ channels are important mechanisms for ABA-induced stomatal closing.
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Affiliation(s)
- Z M Pei
- Division of Biology, Cell and Developmental Biology, and Center for Molecular Genetics, University of California at San Diego, La Jolla 92093-0116, USA
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Hamilton DW, Hills A, Kohler B, Blatt MR. Ca2+ channels at the plasma membrane of stomatal guard cells are activated by hyperpolarization and abscisic acid. Proc Natl Acad Sci U S A 2000; 97:4967-72. [PMID: 10781106 PMCID: PMC18341 DOI: 10.1073/pnas.080068897] [Citation(s) in RCA: 257] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In stomatal guard cells of higher-plant leaves, abscisic acid (ABA) evokes increases in cytosolic free Ca(2+) concentration ([Ca(2+)](i)) by means of Ca(2+) entry from outside and release from intracellular stores. The mechanism(s) for Ca(2+) flux across the plasma membrane is poorly understood. Because [Ca(2+)](i) increases are voltage-sensitive, we suspected a Ca(2+) channel at the guard cell plasma membrane that activates on hyperpolarization and is regulated by ABA. We recorded single-channel currents across the Vicia guard cell plasma membrane using Ba(2+) as a charge-carrying ion. Both cell-attached and excised-patch measurements uncovered single-channel events with a maximum conductance of 12.8 +/- 0.4 pS and a high selectivity for Ba(2+) (and Ca(2+)) over K(+) and Cl(-). Unlike other Ca(2+) channels characterized to date, these channels rectified strongly toward negative voltages with an open probability (P(o)) that increased with [Ba(2+)] outside and decreased roughly 10-fold when [Ca(2+)](i) was raised from 200 nM to 2 microM. Adding 20 microM ABA increased P(o), initially by 63- to 260-fold; in both cell-attached and excised patches, it shifted the voltage sensitivity for channel activation, and evoked damped oscillations in P(o) with periods near 50 s. A similar, but delayed response was observed in 0.1 microM ABA. These results identify a Ca(2+)-selective channel that can account for Ca(2+) influx and increases in [Ca(2+)](i) triggered by voltage and ABA, and they imply a close physical coupling at the plasma membrane between ABA perception and Ca(2+) channel control.
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Affiliation(s)
- D W Hamilton
- Laboratory of Plant Physiology and Biophysics, Imperial College of Science, Technology, and Medicine, Wye, Kent TN25 5AH, England
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Giraudat J, Parcy F, Bertauche N, Gosti F, Leung J, Morris PC, Bouvier-Durand M, Vartanian N. Current advances in abscisic acid action and signalling. PLANT MOLECULAR BIOLOGY 1994; 26:1557-77. [PMID: 7858204 DOI: 10.1007/bf00016490] [Citation(s) in RCA: 130] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Abscisic acid (ABA) participates in the control of diverse physiological processes. The characterization of deficient mutants has clarified the ABA biosynthetic pathway in higher plants. Deficient mutants also lead to a revaluation of the extent of ABA action during seed development and in the response of vegetative tissues to environmental stress. Although ABA receptor(s) have not yet been identified, considerable progress has been recently made in the characterization of more downstream elements of the ABA regulatory network. ABA controls stomatal aperture by rapidly regulating identified ion transporters in guard cells, and the details of the underlying signalling pathways start to emerge. ABA actions in other cell types involve modifications of gene expression. The promoter analysis of ABA-responsive genes has revealed a diversity of cis-acting elements and a few associated trans-acting factors have been isolated. Finally, characterization of mutants defective in ABA responsiveness, and molecular cloning of the corresponding loci, has proven to be a powerful approach to dissect the molecular nature of ABA signalling cascades.
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Affiliation(s)
- J Giraudat
- Institut des Sciences Végétales, Centre National de la Recherche Scientifique UPR 40, Gif-sur-Yvette, France
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Hetherington AM, Quatrano RS. Mechanisms of action of abscisic acid at the cellular level. THE NEW PHYTOLOGIST 1991; 119:9-12. [PMID: 33874327 DOI: 10.1111/j.1469-8137.1991.tb01004.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Abscisic acid (ABA) has been implicated in the control of a diverse range of physiological processes in higher plants. In this review, we focus on the events which constitute the cellular responses to ABA. Current evidence suggests that it is possible to classify the responses to ABA on the basis of whether they are rapid, involving ion fluxes (typified by the stomatal response), or slower and requiring alterations to gene expression (for example the response of cereal embryos to ABA). In our consideration of ABA stimulus response coupling pathways, we have chosen to highlight the role of the calcium ion in the rapid responses, while we have concentrated on the contribution of as-acting elements and trans-acting factors in the regulation of ABA-responsive genes. We also draw attention to the possibility that interaction may exist between these pathways. Additionally, we discuss the controls of ABA concentrations during development and in response to environmental stimuli. Factors which contribute to the controls of ABA sensitivity are also reviewed. In our conclusions, we suggest that a general role for ABA may be to prepare tissue for entry into a new and different physiological state, perhaps by resetting the direction of cellular metabolism. CONTENTS Summary 9 I. Introduction 10 II. Stimulus response coupling 17 Synopsis 27 Acknowledgements 28 References 28.
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Affiliation(s)
| | - Ralph S Quatrano
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599-3280, USA
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