1
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Blatt MR. A charged existence: A century of transmembrane ion transport in plants. PLANT PHYSIOLOGY 2024; 195:79-110. [PMID: 38163639 PMCID: PMC11060664 DOI: 10.1093/plphys/kiad630] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Accepted: 11/01/2023] [Indexed: 01/03/2024]
Abstract
If the past century marked the birth of membrane transport as a focus for research in plants, the past 50 years has seen the field mature from arcane interest to a central pillar of plant physiology. Ion transport across plant membranes accounts for roughly 30% of the metabolic energy consumed by a plant cell, and it underpins virtually every aspect of plant biology, from mineral nutrition, cell expansion, and development to auxin polarity, fertilization, plant pathogen defense, and senescence. The means to quantify ion flux through individual transporters, even single channel proteins, became widely available as voltage clamp methods expanded from giant algal cells to the fungus Neurospora crassa in the 1970s and the cells of angiosperms in the 1980s. Here, I touch briefly on some key aspects of the development of modern electrophysiology with a focus on the guard cells of stomata, now without dispute the premier plant cell model for ion transport and its regulation. Guard cells have proven to be a crucible for many technical and conceptual developments that have since emerged into the mainstream of plant science. Their study continues to provide fundamental insights and carries much importance for the global challenges that face us today.
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Affiliation(s)
- Michael R Blatt
- Laboratory of Plant Physiology and Biophysics, University of Glasgow, Bower Building, Glasgow G12 8QQ, UK
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2
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Silva‐Alvim FAL, Alvim JC, Harvey A, Blatt MR. Speedy stomata of a C 4 plant correlate with enhanced K + channel gating. PLANT, CELL & ENVIRONMENT 2024; 47:817-831. [PMID: 38013592 PMCID: PMC10953386 DOI: 10.1111/pce.14775] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2023] [Revised: 11/08/2023] [Accepted: 11/15/2023] [Indexed: 11/29/2023]
Abstract
Stomata are microscopic pores at the surface of plant leaves that facilitate gaseous diffusion to support photosynthesis. The guard cells around each stoma regulate the pore aperture. Plants that carry out C4 photosynthesis are usually more resilient than C3 plants to stress, and their stomata operate over a lower dynamic range of CO2 within the leaf. What makes guard cells of C4 plants more responsive than those of C3 plants? We used gas exchange and electrophysiology, comparing stomatal kinetics of the C4 plant Gynandropsis gynandra and the phylogenetically related C3 plant Arabidopsis thaliana. We found, with varying CO2 and light, that Gynandropsis showed faster changes in stomata conductance and greater water use efficiency when compared with Arabidopsis. Electrophysiological analysis of the dominant K+ channels showed that the outward-rectifying channels, responsible for K+ loss during stomatal closing, were characterised by a greater maximum conductance and substantial negative shift in the voltage dependence of gating, indicating a reduced inhibition by extracellular K+ and enhanced capacity for K+ flux. These differences correlated with the accelerated stomata kinetics of Gynandropsis, suggesting that subtle changes in the biophysical properties of a key transporter may prove a target for future efforts to engineer C4 stomatal kinetics.
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Affiliation(s)
| | - Jonas Chaves Alvim
- Laboratory of Plant Physiology and Biophysics, Bower BuildingUniversity of GlasgowGlasgowUK
| | - Andy Harvey
- Physics & AstronomyUniversity of GlasgowGlasgowUK
| | - Michael R. Blatt
- Laboratory of Plant Physiology and Biophysics, Bower BuildingUniversity of GlasgowGlasgowUK
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3
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Li K, Grauschopf C, Hedrich R, Dreyer I, Konrad KR. K + and pH homeostasis in plant cells is controlled by a synchronized K + /H + antiport at the plasma and vacuolar membrane. THE NEW PHYTOLOGIST 2024; 241:1525-1542. [PMID: 38017688 DOI: 10.1111/nph.19436] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Accepted: 11/06/2023] [Indexed: 11/30/2023]
Abstract
Stomatal movement involves ion transport across the plasma membrane (PM) and vacuolar membrane (VM) of guard cells. However, the coupling mechanisms of ion transporters in both membranes and their interplay with Ca2+ and pH changes are largely unclear. Here, we investigated transporter networks in tobacco guard cells and mesophyll cells using multiparametric live-cell ion imaging and computational simulations. K+ and anion fluxes at both, PM and VM, affected H+ and Ca2+ , as changes in extracellular KCl or KNO3 concentrations were accompanied by cytosolic and vacuolar pH shifts and changes in [Ca2+ ]cyt and the membrane potential. At both membranes, the K+ transporter networks mediated an antiport of K+ and H+ . By contrast, net transport of anions was accompanied by parallel H+ transport, with differences in transport capacity for chloride and nitrate. Guard and mesophyll cells exhibited similarities in K+ /H+ transport but cell type-specific differences in [H+ ]cyt and pH-dependent [Ca2+ ]cyt signals. Computational cell biology models explained mechanistically the properties of transporter networks and the coupling of transport across the PM and VM. Our integrated approach indicates fundamental principles of coupled ion transport at membrane sandwiches to control H+ /K+ homeostasis and points to transceptor-like Ca2+ /H+ -based ion signaling in plant cells.
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Affiliation(s)
- Kunkun Li
- Department of Botany I, Julius-Von-Sachs Institute for Biosciences, University of Wuerzburg, 97082, Wuerzburg, Germany
| | - Christina Grauschopf
- Department of Botany I, Julius-Von-Sachs Institute for Biosciences, University of Wuerzburg, 97082, Wuerzburg, Germany
| | - Rainer Hedrich
- Department of Botany I, Julius-Von-Sachs Institute for Biosciences, University of Wuerzburg, 97082, Wuerzburg, Germany
| | - Ingo Dreyer
- Faculty of Engineering, Center of Bioinformatics, Simulation and Modeling (CBSM), University of Talca, 3460000, Talca, Chile
| | - Kai R Konrad
- Department of Botany I, Julius-Von-Sachs Institute for Biosciences, University of Wuerzburg, 97082, Wuerzburg, Germany
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4
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Horaruang W, Klejchová M, Carroll W, Silva-Alvim FAL, Waghmare S, Papanatsiou M, Amtmann A, Hills A, Alvim JC, Blatt MR, Zhang B. Engineering a K + channel 'sensory antenna' enhances stomatal kinetics, water use efficiency and photosynthesis. NATURE PLANTS 2022; 8:1262-1274. [PMID: 36266492 DOI: 10.1038/s41477-022-01255-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Accepted: 09/12/2022] [Indexed: 06/16/2023]
Abstract
Stomata of plant leaves open to enable CO2 entry for photosynthesis and close to reduce water loss via transpiration. Compared with photosynthesis, stomata respond slowly to fluctuating light, reducing assimilation and water use efficiency. Efficiency gains are possible without a cost to photosynthesis if stomatal kinetics can be accelerated. Here we show that clustering of the GORK channel, which mediates K+ efflux for stomatal closure in the model plant Arabidopsis, arises from binding between the channel voltage sensors, creating an extended 'sensory antenna' for channel gating. Mutants altered in clustering affect channel gating to facilitate K+ flux, accelerate stomatal movements and reduce water use without a loss in biomass. Our findings identify the mechanism coupling channel clustering with gating, and they demonstrate the potential for engineering of ion channels native to the guard cell to enhance stomatal kinetics and improve water use efficiency without a cost in carbon fixation.
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Affiliation(s)
- Wijitra Horaruang
- Laboratory of Plant Physiology and Biophysics, University of Glasgow, Glasgow, UK
- Faculty of Science and Arts, Burapha University, Chanthaburi Campus, Chanthaburi, Thailand
| | - Martina Klejchová
- Laboratory of Plant Physiology and Biophysics, University of Glasgow, Glasgow, UK
| | - William Carroll
- Laboratory of Plant Physiology and Biophysics, University of Glasgow, Glasgow, UK
| | | | - Sakharam Waghmare
- Laboratory of Plant Physiology and Biophysics, University of Glasgow, Glasgow, UK
| | - Maria Papanatsiou
- Laboratory of Plant Physiology and Biophysics, University of Glasgow, Glasgow, UK
| | - Anna Amtmann
- Laboratory of Plant Physiology and Biophysics, University of Glasgow, Glasgow, UK
| | - Adrian Hills
- Laboratory of Plant Physiology and Biophysics, University of Glasgow, Glasgow, UK
| | - Jonas Chaves Alvim
- Laboratory of Plant Physiology and Biophysics, University of Glasgow, Glasgow, UK
| | - Michael R Blatt
- Laboratory of Plant Physiology and Biophysics, University of Glasgow, Glasgow, UK.
| | - Ben Zhang
- School of Life Sciences, Shanxi University, Taiyuan City, China
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5
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Pei D, Hua D, Deng J, Wang Z, Song C, Wang Y, Wang Y, Qi J, Kollist H, Yang S, Guo Y, Gong Z. Phosphorylation of the plasma membrane H+-ATPase AHA2 by BAK1 is required for ABA-induced stomatal closure in Arabidopsis. THE PLANT CELL 2022; 34:2708-2729. [PMID: 35404404 PMCID: PMC9252505 DOI: 10.1093/plcell/koac106] [Citation(s) in RCA: 37] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Accepted: 04/04/2022] [Indexed: 05/13/2023]
Abstract
Stomatal opening is largely promoted by light-activated plasma membrane-localized proton ATPases (PM H+-ATPases), while their closure is mainly modulated by abscisic acid (ABA) signaling during drought stress. It is unknown whether PM H+-ATPases participate in ABA-induced stomatal closure. We established that BRI1-ASSOCIATED RECEPTOR KINASE 1 (BAK1) interacts with, phosphorylates and activates the major PM Arabidopsis H+-ATPase isoform 2 (AHA2). Detached leaves from aha2-6 single mutant Arabidopsis thaliana plants lost as much water as bak1-4 single and aha2-6 bak1-4 double mutants, with all three mutants losing more water than the wild-type (Columbia-0 [Col-0]). In agreement with these observations, aha2-6, bak1-4, and aha2-6 bak1-4 mutants were less sensitive to ABA-induced stomatal closure than Col-0, whereas the aha2-6 mutation did not affect ABA-inhibited stomatal opening under light conditions. ABA-activated BAK1 phosphorylated AHA2 at Ser-944 in its C-terminus and activated AHA2, leading to rapid H+ efflux, cytoplasmic alkalinization, and reactive oxygen species (ROS) accumulation, to initiate ABA signal transduction and stomatal closure. The phosphorylation-mimicking mutation AHA2S944D driven by its own promoter could largely compensate for the defective phenotypes of water loss, cytoplasmic alkalinization, and ROS accumulation in both aha2-6 and bak1-4 mutants. Our results uncover a crucial role of AHA2 in cytoplasmic alkalinization and ABA-induced stomatal closure during the plant's response to drought stress.
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Affiliation(s)
- Dan Pei
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Deping Hua
- School of Life Sciences, Tianjin University, Tianjin 300072, China
| | - Jinping Deng
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Zhifang Wang
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Chunpeng Song
- Collaborative Innovation Center of Crop Stress Biology, Institute of Plant Stress Biology, Henan University, Kaifeng 475001, China
| | - Yi Wang
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Yu Wang
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Junsheng Qi
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Hannes Kollist
- Plant Signal Research Group, Institute of Technology, University of Tartu, Tartu 50411, Estonia
| | - Shuhua Yang
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Yan Guo
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China
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6
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Lefoulon C. The bare necessities of plant K+ channel regulation. PLANT PHYSIOLOGY 2021; 187:2092-2109. [PMID: 34618033 PMCID: PMC8644596 DOI: 10.1093/plphys/kiab266] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Accepted: 05/11/2021] [Indexed: 05/29/2023]
Abstract
Potassium (K+) channels serve a wide range of functions in plants from mineral nutrition and osmotic balance to turgor generation for cell expansion and guard cell aperture control. Plant K+ channels are members of the superfamily of voltage-dependent K+ channels, or Kv channels, that include the Shaker channels first identified in fruit flies (Drosophila melanogaster). Kv channels have been studied in depth over the past half century and are the best-known of the voltage-dependent channels in plants. Like the Kv channels of animals, the plant Kv channels are regulated over timescales of milliseconds by conformational mechanisms that are commonly referred to as gating. Many aspects of gating are now well established, but these channels still hold some secrets, especially when it comes to the control of gating. How this control is achieved is especially important, as it holds substantial prospects for solutions to plant breeding with improved growth and water use efficiencies. Resolution of the structure for the KAT1 K+ channel, the first channel from plants to be crystallized, shows that many previous assumptions about how the channels function need now to be revisited. Here, I strip the plant Kv channels bare to understand how they work, how they are gated by voltage and, in some cases, by K+ itself, and how the gating of these channels can be regulated by the binding with other protein partners. Each of these features of plant Kv channels has important implications for plant physiology.
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Affiliation(s)
- Cécile Lefoulon
- Laboratory of Plant Physiology and Biophysics, Bower Building, University of Glasgow, Glasgow G12 8QQ, Scotland
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7
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Klejchova M, Silva-Alvim FAL, Blatt MR, Alvim JC. Membrane voltage as a dynamic platform for spatiotemporal signaling, physiological, and developmental regulation. PLANT PHYSIOLOGY 2021; 185:1523-1541. [PMID: 33598675 PMCID: PMC8133626 DOI: 10.1093/plphys/kiab032] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Accepted: 01/11/2021] [Indexed: 05/10/2023]
Abstract
Membrane voltage arises from the transport of ions through ion-translocating ATPases, ion-coupled transport of solutes, and ion channels, and is an integral part of the bioenergetic "currency" of the membrane. The dynamics of membrane voltage-so-called action, systemic, and variation potentials-have also led to a recognition of their contributions to signal transduction, both within cells and across tissues. Here, we review the origins of our understanding of membrane voltage and its place as a central element in regulating transport and signal transmission. We stress the importance of understanding voltage as a common intermediate that acts both as a driving force for transport-an electrical "substrate"-and as a product of charge flux across the membrane, thereby interconnecting all charge-carrying transport across the membrane. The voltage interconnection is vital to signaling via second messengers that rely on ion flux, including cytosolic free Ca2+, H+, and the synthesis of reactive oxygen species generated by integral membrane, respiratory burst oxidases. These characteristics inform on the ways in which long-distance voltage signals and voltage oscillations give rise to unique gene expression patterns and influence physiological, developmental, and adaptive responses such as systemic acquired resistance to pathogens and to insect herbivory.
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Affiliation(s)
- Martina Klejchova
- Laboratory of Plant Physiology and Biophysics, Bower Building, University of Glasgow, Glasgow G12 8QQ, UK
| | - Fernanda A L Silva-Alvim
- Laboratory of Plant Physiology and Biophysics, Bower Building, University of Glasgow, Glasgow G12 8QQ, UK
| | - Michael R Blatt
- Laboratory of Plant Physiology and Biophysics, Bower Building, University of Glasgow, Glasgow G12 8QQ, UK
- Author for communication:
| | - Jonas Chaves Alvim
- Laboratory of Plant Physiology and Biophysics, Bower Building, University of Glasgow, Glasgow G12 8QQ, UK
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8
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Zhou Y, Assmann SM, Jegla T. External Cd2+ and protons activate the hyperpolarization-gated K+ channel KAT1 at the voltage sensor. J Gen Physiol 2021; 153:211573. [PMID: 33275659 PMCID: PMC7721907 DOI: 10.1085/jgp.202012647] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2020] [Revised: 10/21/2020] [Accepted: 11/10/2020] [Indexed: 11/20/2022] Open
Abstract
The functionally diverse cyclic nucleotide binding domain (CNBD) superfamily of cation channels contains both depolarization-gated (e.g., metazoan EAG family K+ channels) and hyperpolarization-gated channels (e.g., metazoan HCN pacemaker cation channels and the plant K+ channel KAT1). In both types of CNBD channels, the S4 transmembrane helix of the voltage sensor domain (VSD) moves outward in response to depolarization. This movement opens depolarization-gated channels and closes hyperpolarization-gated channels. External divalent cations and protons prevent or slow movement of S4 by binding to a cluster of acidic charges on the S2 and S3 transmembrane domains of the VSD and therefore inhibit activation of EAG family channels. However, a similar divalent ion/proton binding pocket has not been described for hyperpolarization-gated CNBD family channels. We examined the effects of external Cd2+ and protons on Arabidopsisthaliana KAT1 expressed in Xenopus oocytes and found that these ions strongly potentiate voltage activation. Cd2+ at 300 µM depolarizes the V50 of KAT1 by 150 mV, while acidification from pH 7.0 to 4.0 depolarizes the V50 by 49 mV. Regulation of KAT1 by Cd2+ is state dependent and consistent with Cd2+ binding to an S4-down state of the VSD. Neutralization of a conserved acidic charge in the S2 helix in KAT1 (D95N) eliminates Cd2+ and pH sensitivity. Conversely, introduction of acidic residues into KAT1 at additional S2 and S3 cluster positions that are charged in EAG family channels (N99D and Q149E in KAT1) decreases Cd2+ sensitivity and increases proton potentiation. These results suggest that KAT1, and presumably other hyperpolarization-gated plant CNBD channels, can open from an S4-down VSD conformation homologous to the divalent/proton-inhibited conformation of EAG family K+ channels.
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Affiliation(s)
- Yunqing Zhou
- Department of Biology, Penn State University, University Park, PA.,Huck Institutes of the Life Sciences, Penn State University, University Park, PA
| | - Sarah M Assmann
- Department of Biology, Penn State University, University Park, PA
| | - Timothy Jegla
- Department of Biology, Penn State University, University Park, PA.,Huck Institutes of the Life Sciences, Penn State University, University Park, PA
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9
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Klejchová M, Hills A, Blatt MR. Predicting the unexpected in stomatal gas exchange: not just an open-and-shut case. Biochem Soc Trans 2020; 48:881-889. [PMID: 32453378 PMCID: PMC7329339 DOI: 10.1042/bst20190632] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2020] [Revised: 05/01/2020] [Accepted: 05/04/2020] [Indexed: 12/22/2022]
Abstract
Plant membrane transport, like transport across all eukaryotic membranes, is highly non-linear and leads to interactions with characteristics so complex that they defy intuitive understanding. The physiological behaviour of stomatal guard cells is a case in point in which, for example, mutations expected to influence stomatal closing have profound effects on stomatal opening and manipulating transport across the vacuolar membrane affects the plasma membrane. Quantitative mathematical modelling is an essential tool in these circumstances, both to integrate the knowledge of each transport process and to understand the consequences of their manipulation in vivo. Here, we outline the OnGuard modelling environment and its use as a guide to predicting the emergent properties arising from the interactions between non-linear transport processes. We summarise some of the recent insights arising from OnGuard, demonstrate its utility in interpreting stomatal behaviour, and suggest ways in which the OnGuard environment may facilitate 'reverse-engineering' of stomata to improve water use efficiency and carbon assimilation.
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Affiliation(s)
- Martina Klejchová
- Laboratory of Plant Physiology and Biophysics, University of Glasgow, Bower Building, Glasgow G12 8QQ, U.K
| | - Adrian Hills
- Laboratory of Plant Physiology and Biophysics, University of Glasgow, Bower Building, Glasgow G12 8QQ, U.K
| | - Michael R. Blatt
- Laboratory of Plant Physiology and Biophysics, University of Glasgow, Bower Building, Glasgow G12 8QQ, U.K
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10
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Lemtiri-Chlieh F, Arold ST, Gehring C. Mg 2+ Is a Missing Link in Plant Cell Ca 2+ Signalling and Homeostasis-A Study on Vicia faba Guard Cells. Int J Mol Sci 2020; 21:ijms21113771. [PMID: 32471040 PMCID: PMC7312177 DOI: 10.3390/ijms21113771] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2020] [Revised: 05/13/2020] [Accepted: 05/15/2020] [Indexed: 01/04/2023] Open
Abstract
Hyperpolarization-activated calcium channels (HACCs) are found in the plasma membrane and tonoplast of many plant cell types, where they have an important role in Ca2+-dependent signalling. The unusual gating properties of HACCs in plants, i.e., activation by membrane hyperpolarization rather than depolarization, dictates that HACCs are normally open in the physiological hyperpolarized resting membrane potential state (the so-called pump or P-state); thus, if not regulated, they would continuously leak Ca2+ into cells. HACCs are permeable to Ca2+, Ba2+, and Mg2+; activated by H2O2 and the plant hormone abscisic acid (ABA); and their activity in guard cells is greatly reduced by increasing amounts of free cytosolic Ca2+ ([Ca2+]Cyt), and hence closes during [Ca2+]Cyt surges. Here, we demonstrate that the presence of the commonly used Mg-ATP inside the guard cell greatly reduces HACC activity, especially at voltages ≤ −200 mV, and that Mg2+ causes this block. Therefore, we firstly conclude that physiological cytosolic Mg2+ levels affect HACC gating and that channel opening requires either high negative voltages (≥−200 mV) or displacement of Mg2+ away from the immediate vicinity of the channel. Secondly, based on structural comparisons with a Mg2+-sensitive animal inward-rectifying K+ channel, we propose that the likely candidate HACCs described here are cyclic nucleotide gated channels (CNGCs), many of which also contain a conserved diacidic Mg2+ binding motif within their pores. This conclusion is consistent with the electrophysiological data. Finally, we propose that Mg2+, much like in animal cells, is an important component in Ca2+ signalling and homeostasis in plants.
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Affiliation(s)
- Fouad Lemtiri-Chlieh
- King Abdullah University of Science and Technology (KAUST), Biological and Environmental Science and Engineering (BESE), Thuwal 23955-6900, Saudi Arabia;
- Department of Neuroscience, University of Connecticut School of Medicine, Farmington, CT 06030, USA
- Correspondence: (F.L.-C); (C.G.)
| | - Stefan T. Arold
- King Abdullah University of Science and Technology (KAUST), Biological and Environmental Science and Engineering (BESE), Thuwal 23955-6900, Saudi Arabia;
- King Abdullah University of Science and Technology (KAUST), Computational Bioscience Research Center (CBRC), Thuwal 23955-6900, Saudi Arabia
- Centre de Biochimie Structurale, CNRS, INSERM, Université de Montpellier, 34090 Montpellier, France
| | - Chris Gehring
- King Abdullah University of Science and Technology (KAUST), Biological and Environmental Science and Engineering (BESE), Thuwal 23955-6900, Saudi Arabia;
- Department of Chemistry, Biology & Biotechnology, University of Perugia, 06121 Perugia, Italy
- Correspondence: (F.L.-C); (C.G.)
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11
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Gao YQ, Wu WH, Wang Y. Electrophysiological Identification and Activity Analyses of Plasma Membrane K+ Channels in Maize Guard Cells. PLANT & CELL PHYSIOLOGY 2019; 60:765-777. [PMID: 30590755 DOI: 10.1093/pcp/pcy242] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2017] [Accepted: 12/19/2018] [Indexed: 05/11/2023]
Abstract
Stomatal movement, which plays an essential role in plant transpiration and photosynthesis, is controlled by ion channels that mediate K+ and anion fluxes across the plasma membrane (PM) of guard cells. These channels in dicots are accurately regulated by various physiological factors, such as pH, abscisic acid (ABA) and Ca2+; however, the data in monocots are limited. Here the whole-cell patch-clamping technique was applied to analyze the properties and regulations of PM K+ channels in maize guard cells. The results indicated that the hyperpolarization-activated inward-rectifying channels were highly K+-selective. These inward K+ (Kin) channels were sensitive to extracellular K+. Their slope factor (S) decreased when the apoplastic K+ concentration decline, causing a positive shift of the half-activation potential (V1/2). Their activities were promoted by apoplastic acidification but inhibited by apoplastic and cytosolic alkalization. Nevertheless, the outward K+ (Kout) channel activities were uniquely promoted by cytosolic alkalization. Both apoplastic and cytosolic ABA inhibited Kin channels independent of cytosolic Ca2+ ([Ca2+]cyt). And two Ca2+-dependent mechanisms with different Ca2+ affinities may mediate resting- and high-[Ca2+]cyt-induced inhibition on Kin channels, respectively. However, resting [Ca2+]cyt impaired the inhibition of Kin channels induced by apoplastic ABA, not cytosolic ABA. Furthermore, the result that high [Ca2+]cyt attenuated ABA-induced inhibition highlighted the importance of [Ca2+]cyt for Kin channel regulation. There may exist a Ca2+-dependent regulation of the Ca2+-independent ABA signaling pathways for Kin channel inhibition. These results provided an electrophysiological view of the multiple level regulations of PM K+ channel activities and kinetics in maize guard cells.
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Affiliation(s)
- Yong-Qiang Gao
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing, China
- Center for Crop Functional Genomics and Molecular Breeding, China Agricultural University, Beijing, China
| | - Wei-Hua Wu
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing, China
- Center for Crop Functional Genomics and Molecular Breeding, China Agricultural University, Beijing, China
| | - Yi Wang
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing, China
- Center for Crop Functional Genomics and Molecular Breeding, China Agricultural University, Beijing, China
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12
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Gao YQ, Wu WH, Wang Y. The K + channel KZM2 is involved in stomatal movement by modulating inward K + currents in maize guard cells. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2017; 92:662-675. [PMID: 28891257 DOI: 10.1111/tpj.13712] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Revised: 08/28/2017] [Accepted: 09/01/2017] [Indexed: 06/07/2023]
Abstract
Stomata are the major gates in plant leaf that allow water and gas exchange, which is essential for plant transpiration and photosynthesis. Stomatal movement is mainly controlled by the ion channels and transporters in guard cells. In Arabidopsis, the inward Shaker K+ channels, such as KAT1 and KAT2, are responsible for stomatal opening. However, the characterization of inward K+ channels in maize guard cells is limited. In the present study, we identified two KAT1-like Shaker K+ channels, KZM2 and KZM3, which were highly expressed in maize guard cells. Subcellular analysis indicated that KZM2 and KZM3 can localize at the plasma membrane. Electrophysiological characterization in HEK293 cells revealed that both KZM2 and KZM3 were inward K+ (Kin ) channels, but showing distinct channel kinetics. When expressed in Xenopus oocytes, only KZM3, but not KZM2, can mediate inward K+ currents. However, KZM2 can interact with KZM3 forming heteromeric Kin channel. In oocytes, KZM2 inhibited KZM3 channel conductance and negatively shifted the voltage dependence of KZM3. The activation of KZM2-KZM3 heteromeric channel became slower than the KZM3 channel. Patch-clamping results showed that the inward K+ currents of maize guard cells were significantly increased in the KZM2 RNAi lines. In addition, the RNAi lines exhibited faster stomatal opening after light exposure. In conclusion, the presented results demonstrate that KZM2 functions as a negative regulator to modulate the Kin channels in maize guard cells. KZM2 and KZM3 may form heteromeric Kin channel and control stomatal opening in maize.
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Affiliation(s)
- Yong-Qiang Gao
- State Key Laboratory of Plant Physiology and Biochemistry (SKLPPB), College of Biological Sciences, China Agricultural University, Beijing, 100193, China
| | - Wei-Hua Wu
- State Key Laboratory of Plant Physiology and Biochemistry (SKLPPB), College of Biological Sciences, China Agricultural University, Beijing, 100193, China
| | - Yi Wang
- State Key Laboratory of Plant Physiology and Biochemistry (SKLPPB), College of Biological Sciences, China Agricultural University, Beijing, 100193, China
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13
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Geilfus CM, Tenhaken R, Carpentier SC. Transient alkalinization of the leaf apoplast stiffens the cell wall during onset of chloride salinity in corn leaves. J Biol Chem 2017; 292:18800-18813. [PMID: 28972176 DOI: 10.1074/jbc.m117.799866] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Revised: 09/11/2017] [Indexed: 12/13/2022] Open
Abstract
During chloride salinity, the pH of the leaf apoplast (pHapo) transiently alkalizes. There is an ongoing debate about the physiological relevance of these stress-induced pHapo changes. Using proteomic analyses of expanding leaves of corn (Zea mays L.), we show that this transition in pHapo conveys functionality by (i) adjusting protein abundances and (ii) affecting the rheological properties of the cell wall. pHapo was monitored in planta via microscopy-based ratio imaging, and the leaf-proteomic response to the transient leaf apoplastic alkalinization was analyzed via ultra-high performance liquid chromatography-MS. This analysis identified 1459 proteins, of which 44 exhibited increased abundance specifically through the chloride-induced transient rise in pHapo These elevated protein abundances did not directly arise from high tissue concentrations of Cl- or Na+ but were due to changes in the pHapo Most of these proteins functioned in growth-relevant processes and in the synthesis of cell wall-building components such as arabinose. Measurements with a linear-variable differential transducer revealed that the transient alkalinization rigidified (i.e. stiffened) the cell wall during the onset of chloride salinity. A decrease in t-coumaric and t-ferulic acids indicates that the wall stiffening arises from cross-linkage to cell wall polymers. We conclude that the pH of the apoplast represents a dynamic factor that is mechanistically coupled to cellular responses to chloride stress. By hardening the wall, the increased pH abrogates wall loosening required for cell expansion and growth. We conclude that the transient alkalinization of the leaf apoplast is related to salinity-induced growth reduction.
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Affiliation(s)
- Christoph-Martin Geilfus
- From SYBIOMA, Proteomics Core Facility, KU Leuven, O&N II Herestraat 49, bus 901, B-3000 Leuven, Belgium, .,the Albrecht Daniel Thaer-Institute of Agricultural and Horticultural Sciences, Humboldt-University of Berlin, Albrecht-Thaer-Weg 1, 14195 Berlin, Germany
| | - Raimund Tenhaken
- the Department of Cell Biology, Division of Plant Physiology, University of Salzburg, Salzburg, Austria, and
| | - Sebastien Christian Carpentier
- From SYBIOMA, Proteomics Core Facility, KU Leuven, O&N II Herestraat 49, bus 901, B-3000 Leuven, Belgium.,the Department of Biosystems, Division of Crop Biotechnics, KU Leuven, Willem de Croylaan 42, Box 2455, B-3001 Leuven, Belgium
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14
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Jezek M, Blatt MR. The Membrane Transport System of the Guard Cell and Its Integration for Stomatal Dynamics. PLANT PHYSIOLOGY 2017; 174:487-519. [PMID: 28408539 PMCID: PMC5462021 DOI: 10.1104/pp.16.01949] [Citation(s) in RCA: 180] [Impact Index Per Article: 25.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Accepted: 04/11/2017] [Indexed: 05/17/2023]
Abstract
Stomatal guard cells are widely recognized as the premier plant cell model for membrane transport, signaling, and homeostasis. This recognition is rooted in half a century of research into ion transport across the plasma and vacuolar membranes of guard cells that drive stomatal movements and the signaling mechanisms that regulate them. Stomatal guard cells surround pores in the epidermis of plant leaves, controlling the aperture of the pore to balance CO2 entry into the leaf for photosynthesis with water loss via transpiration. The position of guard cells in the epidermis is ideally suited for cellular and subcellular research, and their sensitivity to endogenous signals and environmental stimuli makes them a primary target for physiological studies. Stomata underpin the challenges of water availability and crop production that are expected to unfold over the next 20 to 30 years. A quantitative understanding of how ion transport is integrated and controlled is key to meeting these challenges and to engineering guard cells for improved water use efficiency and agricultural yields.
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Affiliation(s)
- Mareike Jezek
- Laboratory of Plant Physiology and Biophysics, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - Michael R Blatt
- Laboratory of Plant Physiology and Biophysics, University of Glasgow, Glasgow G12 8QQ, United Kingdom
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15
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Santelia D, Lawson T. Rethinking Guard Cell Metabolism. PLANT PHYSIOLOGY 2016; 172:1371-1392. [PMID: 27609861 PMCID: PMC5100799 DOI: 10.1104/pp.16.00767] [Citation(s) in RCA: 76] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Accepted: 08/27/2016] [Indexed: 05/18/2023]
Abstract
Stomata control gaseous fluxes between the internal leaf air spaces and the external atmosphere and, therefore, play a pivotal role in regulating CO2 uptake for photosynthesis as well as water loss through transpiration. Guard cells, which flank the stomata, undergo adjustments in volume, resulting in changes in pore aperture. Stomatal opening is mediated by the complex regulation of ion transport and solute biosynthesis. Ion transport is exceptionally well understood, whereas our knowledge of guard cell metabolism remains limited, despite several decades of research. In this review, we evaluate the current literature on metabolism in guard cells, particularly the roles of starch, sucrose, and malate. We explore the possible origins of sucrose, including guard cell photosynthesis, and discuss new evidence that points to multiple processes and plasticity in guard cell metabolism that enable these cells to function effectively to maintain optimal stomatal aperture. We also discuss the new tools, techniques, and approaches available for further exploring and potentially manipulating guard cell metabolism to improve plant water use and productivity.
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Affiliation(s)
- Diana Santelia
- Department of Plant and Microbial Biology, University of Zürich, 8008 Zurich, Switzerland (D.S.); and
- School of Biological Science, University of Essex, Colchester CO4 3SQ, United Kingdom (T.L.)
| | - Tracy Lawson
- Department of Plant and Microbial Biology, University of Zürich, 8008 Zurich, Switzerland (D.S.); and
- School of Biological Science, University of Essex, Colchester CO4 3SQ, United Kingdom (T.L.)
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16
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Papanatsiou M, Amtmann A, Blatt MR. Stomatal Spacing Safeguards Stomatal Dynamics by Facilitating Guard Cell Ion Transport Independent of the Epidermal Solute Reservoir. PLANT PHYSIOLOGY 2016; 172:254-63. [PMID: 27406168 PMCID: PMC5074606 DOI: 10.1104/pp.16.00850] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Accepted: 07/09/2016] [Indexed: 05/06/2023]
Abstract
Stomata enable gaseous exchange between the interior of the leaf and the atmosphere through the stomatal pore. Control of the pore aperture depends on osmotic solute accumulation by, and its loss from the guard cells surrounding the pore. Stomata in most plants are separated by at least one epidermal cell, and this spacing is thought to enhance stomatal function, although there are several genera that exhibit stomata in clusters. We made use of Arabidopsis (Arabidopsis thaliana) stomatal patterning mutants to explore the impact of clustering on guard cell dynamics, gas exchange, and ion transport of guard cells. These studies showed that stomatal clustering in the Arabidopsis too many mouths (tmm1) mutant suppressed stomatal movements and affected CO2 assimilation and transpiration differentially between dark and light conditions and were associated with alterations in K(+) channel gating. These changes were consistent with the impaired dynamics of tmm1 stomata and were accompanied by a reduced accumulation of K(+) ions in the guard cells. Our findings underline the significance of spacing for stomatal dynamics. While stomatal spacing may be important as a reservoir for K(+) and other ions to facilitate stomatal movements, the effects on channel gating, and by inference on K(+) accumulation, cannot be explained on the basis of a reduced number of epidermal cells facilitating ion supply to the guard cells.
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Affiliation(s)
- Maria Papanatsiou
- Institute of Molecular Plant Science, School of Biology, University of Edinburgh, Edinburgh EH9 3JR, United Kingdom (M.P.); andLaboratory of Plant Physiology and Biophysics, Institute of Molecular, Cell, and Systems Biology, University of Glasgow, Glasgow G12 8QQ, United Kingdom (M.P., A.A., M.R.B.)
| | - Anna Amtmann
- Institute of Molecular Plant Science, School of Biology, University of Edinburgh, Edinburgh EH9 3JR, United Kingdom (M.P.); andLaboratory of Plant Physiology and Biophysics, Institute of Molecular, Cell, and Systems Biology, University of Glasgow, Glasgow G12 8QQ, United Kingdom (M.P., A.A., M.R.B.)
| | - Michael R Blatt
- Institute of Molecular Plant Science, School of Biology, University of Edinburgh, Edinburgh EH9 3JR, United Kingdom (M.P.); andLaboratory of Plant Physiology and Biophysics, Institute of Molecular, Cell, and Systems Biology, University of Glasgow, Glasgow G12 8QQ, United Kingdom (M.P., A.A., M.R.B.)
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17
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Li J, Zhang H, Lei H, Jin M, Yue G, Su Y. Functional identification of a GORK potassium channel from the ancient desert shrub Ammopiptanthus mongolicus (Maxim.) Cheng f. PLANT CELL REPORTS 2016; 35:803-15. [PMID: 26804987 DOI: 10.1007/s00299-015-1922-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2015] [Accepted: 12/09/2015] [Indexed: 05/15/2023]
Abstract
A GORK homologue K(+) channel from the ancient desert shrub Ammopiptanthus mongolicus (Maxim.) Cheng f. shows the functional conservation of the GORK channels among plant species. Guard cell K(+) release through the outward potassium channels eventually enables the closure of stomata which consequently prevents plant water loss from severe transpiration. Early patch-clamp studies with the guard cells have revealed many details of such outward potassium currents. However, genes coding for these potassium-release channels have not been sufficiently characterized from species other than the model plant Arabidopsis thaliana. We report here the functional identification of a GORK (for Gated or Guard cell Outward Rectifying K(+) channels) homologue from the ancient desert shrub Ammopiptanthus mongolicus (Maxim.) Cheng f. AmGORK was primary expressed in shoots, where the transcripts were regulated by stress factors simulated by PEG, NaCl or ABA treatments. Patch-clamp measurements on isolated guard cell protoplasts revealed typical depolarization voltage gated outward K(+) currents sensitive to the extracelluar K(+) concentration and pH, resembling the fundamental properties previously described in other species. Two-electrode voltage-clamp analysis in Xenopus lavies oocytes with AmGORK reconstituted highly similar characteristics as assessed in the guard cells, supporting that the function of AmGORK is consistent with a crucial role in mediating stomatal closure in Ammopiptanthus mongolicus. Furthermore, a single amino acid mutation D297N of AmGORK eventually abolishes both the voltage-gating and its outward rectification and converts the channel into a leak-like channel, indicating strong involvement of this residue in the gating and voltage dependence of AmGORK. Our results obtained from this anciently originated plant support a strong functional conservation of the GORK channels among plant species and maybe also along the progress of revolution.
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Affiliation(s)
- Junlin Li
- College of Forestry, Nanjing Forestry University, Nanjing, 210037, China
- Co-Innovation Center for the Sustainable Forestry in Southern China, Nanjing Forest University, Nanjing, 210037, China
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, China
| | - Huanchao Zhang
- College of Forestry, Nanjing Forestry University, Nanjing, 210037, China
- Co-Innovation Center for the Sustainable Forestry in Southern China, Nanjing Forest University, Nanjing, 210037, China
| | - Han Lei
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, China
| | - Man Jin
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, China
| | - Guangzhen Yue
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, China
| | - Yanhua Su
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, China.
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18
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Chen ZH, Wang Y, Wang JW, Babla M, Zhao C, García-Mata C, Sani E, Differ C, Mak M, Hills A, Amtmann A, Blatt MR. Nitrate reductase mutation alters potassium nutrition as well as nitric oxide-mediated control of guard cell ion channels in Arabidopsis. THE NEW PHYTOLOGIST 2016; 209:1456-69. [PMID: 26508536 DOI: 10.1111/nph.13714] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2015] [Accepted: 09/17/2015] [Indexed: 05/04/2023]
Abstract
Maintaining potassium (K(+) ) nutrition and a robust guard cell K(+) inward channel activity is considered critical for plants' adaptation to fluctuating and challenging growth environment. ABA induces stomatal closure through hydrogen peroxide and nitric oxide (NO) along with subsequent ion channel-mediated loss of K(+) and anions. However, the interactions of NO synthesis and signalling with K(+) nutrition and guard cell K(+) channel activities have not been fully explored in Arabidopsis. Physiological and molecular techniques were employed to dissect the interaction of nitrogen and potassium nutrition in regulating stomatal opening, CO2 assimilation and ion channel activity. These data, gene expression and ABA signalling transduction were compared in wild-type Columbia-0 (Col-0) and the nitrate reductase mutant nia1nia2. Growth and K(+) nutrition were impaired along with stomatal behaviour, membrane transport, and expression of genes associated with ABA signalling in the nia1nia2 mutant. ABA-inhibited K(+) in current and ABA-enhanced slow anion current were absent in nia1nia2. Exogenous NO restored regulation of these channels for complete stomatal closure in nia1nia2. While NO is an important signalling component in ABA-induced stomatal closure in Arabidopsis, our findings demonstrate a more complex interaction associating potassium nutrition and nitrogen metabolism in the nia1nia2 mutant that affects stomatal function.
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Affiliation(s)
- Zhong-Hua Chen
- College of Agriculture and Biotechnology, Zhejiang University, Hangzhou, 310058, China
- School of Science and Health, Western Sydney University, Penrith, NSW, 2751, Australia
| | - Yizhou Wang
- Laboratory of Plant Physiology and Biophysics, University of Glasgow, Bower Building, Glasgow, G12 8QQ, UK
| | - Jian-Wen Wang
- College of Pharmaceutical Sciences, Soochow University, Suzhou, 215123, China
| | - Mohammad Babla
- School of Science and Health, Western Sydney University, Penrith, NSW, 2751, Australia
| | - Chenchen Zhao
- School of Science and Health, Western Sydney University, Penrith, NSW, 2751, Australia
| | - Carlos García-Mata
- Instituto de Investigaciones Biológicas, CONCIET-Universidad Nacional de Mar del Plata, CC 1245, 7600, Mar del Plata, Argentina
| | - Emanuela Sani
- Laboratory of Plant Physiology and Biophysics, University of Glasgow, Bower Building, Glasgow, G12 8QQ, UK
| | - Christopher Differ
- Laboratory of Plant Physiology and Biophysics, University of Glasgow, Bower Building, Glasgow, G12 8QQ, UK
| | - Michelle Mak
- School of Science and Health, Western Sydney University, Penrith, NSW, 2751, Australia
| | - Adrian Hills
- Laboratory of Plant Physiology and Biophysics, University of Glasgow, Bower Building, Glasgow, G12 8QQ, UK
| | - Anna Amtmann
- Laboratory of Plant Physiology and Biophysics, University of Glasgow, Bower Building, Glasgow, G12 8QQ, UK
| | - Michael R Blatt
- Laboratory of Plant Physiology and Biophysics, University of Glasgow, Bower Building, Glasgow, G12 8QQ, UK
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19
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Nieves-Cordones M, Martínez V, Benito B, Rubio F. Comparison between Arabidopsis and Rice for Main Pathways of K(+) and Na(+) Uptake by Roots. FRONTIERS IN PLANT SCIENCE 2016; 7:992. [PMID: 27458473 PMCID: PMC4932104 DOI: 10.3389/fpls.2016.00992] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Accepted: 06/22/2016] [Indexed: 05/22/2023]
Abstract
K(+) is an essential macronutrient for plants. It is acquired by specific uptake systems located in roots. Although the concentrations of K(+) in the soil solution are widely variable, K(+) nutrition is secured by uptake systems that exhibit different affinities for K(+). Two main systems have been described for root K(+) uptake in several species: the high-affinity HAK5-like transporter and the inward-rectifier AKT1-like channel. Other unidentified systems may be also involved in root K(+) uptake, although they only seem to operate when K(+) is not limiting. The use of knock-out lines has allowed demonstrating their role in root K(+) uptake in Arabidopsis and rice. Plant adaptation to the different K(+) supplies relies on the finely tuned regulation of these systems. Low K(+)-induced transcriptional up-regulation of the genes encoding HAK5-like transporters occurs through a signal cascade that includes changes in the membrane potential of root cells and increases in ethylene and reactive oxygen species concentrations. Activation of AKT1 channels occurs through phosphorylation by the CIPK23/CBL1 complex. Recently, activation of the Arabidopsis HAK5 by the same complex has been reported, pointing to CIPK23/CBL as a central regulator of the plant's adaptation to low K(+). Na(+) is not an essential plant nutrient but it may be beneficial for some plants. At low concentrations, Na(+) improves growth, especially under K(+) deficiency. Thus, high-affinity Na(+) uptake systems have been described that belong to the HKT and HAK families of transporters. At high concentrations, typical of saline environments, Na(+) accumulates in plant tissues at high concentrations, producing alterations that include toxicity, water deficit and K(+) deficiency. Data concerning pathways for Na(+) uptake into roots under saline conditions are still scarce, although several possibilities have been proposed. The apoplast is a significant pathway for Na(+) uptake in rice grown under salinity conditions, but in other plant species different mechanisms involving non-selective cation channels or transporters are under discussion.
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Affiliation(s)
- Manuel Nieves-Cordones
- Biochimie et Physiologie Moléculaire des Plantes, Institut de Biologie Intégrative des Plantes, UMR 5004 CNRS/UMR 0386 INRA/Montpellier SupAgro/Université Montpellier 2Montpellier, France
| | - Vicente Martínez
- Departamento de Nutrición Vegetal, Centro de Edafología y Biología Aplicada del Segura – Consejo Superior de Investigaciones CientíficasMurcia, Spain
| | - Begoña Benito
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de MadridMadrid, Spain
| | - Francisco Rubio
- Departamento de Nutrición Vegetal, Centro de Edafología y Biología Aplicada del Segura – Consejo Superior de Investigaciones CientíficasMurcia, Spain
- *Correspondence: Francisco Rubio,
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20
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Muralidhar A, Shabala L, Broady P, Shabala S, Garrill A. Mechanisms underlying turgor regulation in the estuarine alga Vaucheria erythrospora (Xanthophyceae) exposed to hyperosmotic shock. PLANT, CELL & ENVIRONMENT 2015; 38:1514-1527. [PMID: 25546818 DOI: 10.1111/pce.12503] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2014] [Revised: 12/07/2014] [Accepted: 12/11/2014] [Indexed: 06/04/2023]
Abstract
Aquatic organisms are often exposed to dramatic changes in salinity in the environment. Despite decades of research, many questions related to molecular and physiological mechanisms mediating sensing and adaptation to salinity stress remain unanswered. Here, responses of Vaucheria erythrospora, a turgor-regulating xanthophycean alga from an estuarine habitat, have been investigated. The role of ion uptake in turgor regulation was studied using a single cell pressure probe, microelectrode ion flux estimation (MIFE) technique and membrane potential (Em ) measurements. Turgor recovery was inhibited by Gd(3+) , tetraethylammonium chloride (TEA), verapamil and orthovanadate. A NaCl-induced shock rapidly depolarized the plasma membrane while an isotonic sorbitol treatment hyperpolarized it. Turgor recovery was critically dependent on the presence of Na(+) but not K(+) and Cl(-) in the incubation media. Na(+) uptake was strongly decreased by amiloride and changes in net Na(+) and H(+) fluxes were oppositely directed. This suggests active uptake of Na(+) in V. erythrospora mediated by an antiport Na(+) /H(+) system, functioning in the direction opposite to that of the SOS1 exchanger in higher plants. The alga also retains K(+) efficiently when exposed to high NaCl concentrations. Overall, this study provides insights into mechanisms enabling V. erythrospora to regulate turgor via ion movements during hyperosmotic stress.
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Affiliation(s)
- Abishek Muralidhar
- School of Biological Sciences, University of Canterbury, Christchurch, 8011, New Zealand
| | - Lana Shabala
- School of Land and Food and Tasmanian Institute for Agriculture, University of Tasmania, Hobart, Tasmania, 7001, Australia
| | - Paul Broady
- School of Biological Sciences, University of Canterbury, Christchurch, 8011, New Zealand
| | - Sergey Shabala
- School of Land and Food and Tasmanian Institute for Agriculture, University of Tasmania, Hobart, Tasmania, 7001, Australia
| | - Ashley Garrill
- School of Biological Sciences, University of Canterbury, Christchurch, 8011, New Zealand
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21
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Papanatsiou M, Scuffi D, Blatt MR, García-Mata C. Hydrogen sulfide regulates inward-rectifying K+ channels in conjunction with stomatal closure. PLANT PHYSIOLOGY 2015; 168:29-35. [PMID: 25770153 PMCID: PMC4424018 DOI: 10.1104/pp.114.256057] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Accepted: 03/11/2015] [Indexed: 05/20/2023]
Abstract
Hydrogen sulfide (H2S) is the third biological gasotransmitter, and in animals, it affects many physiological processes by modulating ion channels. H2S has been reported to protect plants from oxidative stress in diverse physiological responses. H2S closes stomata, but the underlying mechanism remains elusive. Here, we report the selective inactivation of current carried by inward-rectifying K(+) channels of tobacco (Nicotiana tabacum) guard cells and show its close parallel with stomatal closure evoked by submicromolar concentrations of H2S. Experiments to scavenge H2S suggested an effect that is separable from that of abscisic acid, which is associated with water stress. Thus, H2S seems to define a unique and unresolved signaling pathway that selectively targets inward-rectifying K(+) channels.
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Affiliation(s)
- Maria Papanatsiou
- Laboratory of Plant Physiology and Biophysics, Institute of Molecular, Cell and Systems Biology, University of Glasgow, Glasgow G12 8QQ, United Kingdom (M.P., M.R.B.); andInstituto de Investigaciones Biológicas, Universidad Nacional de Mar del Plata, Consejo Nacional de Investigaciones Científicas y Técnicas, 7600 Mar del Plata, Argentina (D.S., C.G.-M.)
| | - Denisse Scuffi
- Laboratory of Plant Physiology and Biophysics, Institute of Molecular, Cell and Systems Biology, University of Glasgow, Glasgow G12 8QQ, United Kingdom (M.P., M.R.B.); andInstituto de Investigaciones Biológicas, Universidad Nacional de Mar del Plata, Consejo Nacional de Investigaciones Científicas y Técnicas, 7600 Mar del Plata, Argentina (D.S., C.G.-M.)
| | - Michael R Blatt
- Laboratory of Plant Physiology and Biophysics, Institute of Molecular, Cell and Systems Biology, University of Glasgow, Glasgow G12 8QQ, United Kingdom (M.P., M.R.B.); andInstituto de Investigaciones Biológicas, Universidad Nacional de Mar del Plata, Consejo Nacional de Investigaciones Científicas y Técnicas, 7600 Mar del Plata, Argentina (D.S., C.G.-M.)
| | - Carlos García-Mata
- Laboratory of Plant Physiology and Biophysics, Institute of Molecular, Cell and Systems Biology, University of Glasgow, Glasgow G12 8QQ, United Kingdom (M.P., M.R.B.); andInstituto de Investigaciones Biológicas, Universidad Nacional de Mar del Plata, Consejo Nacional de Investigaciones Científicas y Técnicas, 7600 Mar del Plata, Argentina (D.S., C.G.-M.)
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22
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Cotelle V, Leonhardt N. 14-3-3 Proteins in Guard Cell Signaling. FRONTIERS IN PLANT SCIENCE 2015; 6:1210. [PMID: 26858725 PMCID: PMC4729941 DOI: 10.3389/fpls.2015.01210] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Accepted: 12/15/2015] [Indexed: 05/19/2023]
Abstract
Guard cells are specialized cells located at the leaf surface delimiting pores which control gas exchanges between the plant and the atmosphere. To optimize the CO2 uptake necessary for photosynthesis while minimizing water loss, guard cells integrate environmental signals to adjust stomatal aperture. The size of the stomatal pore is regulated by movements of the guard cells driven by variations in their volume and turgor. As guard cells perceive and transduce a wide array of environmental cues, they provide an ideal system to elucidate early events of plant signaling. Reversible protein phosphorylation events are known to play a crucial role in the regulation of stomatal movements. However, in some cases, phosphorylation alone is not sufficient to achieve complete protein regulation, but is necessary to mediate the binding of interactors that modulate protein function. Among the phosphopeptide-binding proteins, the 14-3-3 proteins are the best characterized in plants. The 14-3-3s are found as multiple isoforms in eukaryotes and have been shown to be involved in the regulation of stomatal movements. In this review, we describe the current knowledge about 14-3-3 roles in the regulation of their binding partners in guard cells: receptors, ion pumps, channels, protein kinases, and some of their substrates. Regulation of these targets by 14-3-3 proteins is discussed and related to their function in guard cells during stomatal movements in response to abiotic or biotic stresses.
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Affiliation(s)
- Valérie Cotelle
- Laboratoire de Recherche en Sciences Végétales, Université de Toulouse, CNRS, UPSCastanet-Tolosan, France
- *Correspondence: Valérie Cotelle,
| | - Nathalie Leonhardt
- UMR7265, Laboratoire de Biologie du Développement des Plantes, Service de Biologie Végétale et de Microbiologie Environnementales, Institut de Biologie Environnementale et Biotechnologie, CNRS–CEA–Université Aix-MarseilleSaint-Paul-lez-Durance, France
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23
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Cotelle V, Leonhardt N. 14-3-3 Proteins in Guard Cell Signaling. FRONTIERS IN PLANT SCIENCE 2015. [PMID: 26858725 DOI: 10.3389/fpis.2015.01210] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Guard cells are specialized cells located at the leaf surface delimiting pores which control gas exchanges between the plant and the atmosphere. To optimize the CO2 uptake necessary for photosynthesis while minimizing water loss, guard cells integrate environmental signals to adjust stomatal aperture. The size of the stomatal pore is regulated by movements of the guard cells driven by variations in their volume and turgor. As guard cells perceive and transduce a wide array of environmental cues, they provide an ideal system to elucidate early events of plant signaling. Reversible protein phosphorylation events are known to play a crucial role in the regulation of stomatal movements. However, in some cases, phosphorylation alone is not sufficient to achieve complete protein regulation, but is necessary to mediate the binding of interactors that modulate protein function. Among the phosphopeptide-binding proteins, the 14-3-3 proteins are the best characterized in plants. The 14-3-3s are found as multiple isoforms in eukaryotes and have been shown to be involved in the regulation of stomatal movements. In this review, we describe the current knowledge about 14-3-3 roles in the regulation of their binding partners in guard cells: receptors, ion pumps, channels, protein kinases, and some of their substrates. Regulation of these targets by 14-3-3 proteins is discussed and related to their function in guard cells during stomatal movements in response to abiotic or biotic stresses.
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Affiliation(s)
- Valérie Cotelle
- Laboratoire de Recherche en Sciences Végétales, Université de Toulouse, CNRS, UPS Castanet-Tolosan, France
| | - Nathalie Leonhardt
- UMR7265, Laboratoire de Biologie du Développement des Plantes, Service de Biologie Végétale et de Microbiologie Environnementales, Institut de Biologie Environnementale et Biotechnologie, CNRS-CEA-Université Aix-Marseille Saint-Paul-lez-Durance, France
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Sun Z, Jin X, Albert R, Assmann SM. Multi-level modeling of light-induced stomatal opening offers new insights into its regulation by drought. PLoS Comput Biol 2014; 10:e1003930. [PMID: 25393147 PMCID: PMC4230748 DOI: 10.1371/journal.pcbi.1003930] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2014] [Accepted: 09/19/2014] [Indexed: 12/17/2022] Open
Abstract
Plant guard cells gate CO2 uptake and transpirational water loss through stomatal pores. As a result of decades of experimental investigation, there is an abundance of information on the involvement of specific proteins and secondary messengers in the regulation of stomatal movements and on the pairwise relationships between guard cell components. We constructed a multi-level dynamic model of guard cell signal transduction during light-induced stomatal opening and of the effect of the plant hormone abscisic acid (ABA) on this process. The model integrates into a coherent network the direct and indirect biological evidence regarding the regulation of seventy components implicated in stomatal opening. Analysis of this signal transduction network identified robust cross-talk between blue light and ABA, in which [Ca2+]c plays a key role, and indicated an absence of cross-talk between red light and ABA. The dynamic model captured more than 10(31) distinct states for the system and yielded outcomes that were in qualitative agreement with a wide variety of previous experimental results. We obtained novel model predictions by simulating single component knockout phenotypes. We found that under white light or blue light, over 60%, and under red light, over 90% of all simulated knockouts had similar opening responses as wild type, showing that the system is robust against single node loss. The model revealed an open question concerning the effect of ABA on red light-induced stomatal opening. We experimentally showed that ABA is able to inhibit red light-induced stomatal opening, and our model offers possible hypotheses for the underlying mechanism, which point to potential future experiments. Our modelling methodology combines simplicity and flexibility with dynamic richness, making it well suited for a wide class of biological regulatory systems.
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Affiliation(s)
- Zhongyao Sun
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Xiaofen Jin
- Department of Biology, The Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Réka Albert
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania, United States of America
- Department of Biology, The Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Sarah M. Assmann
- Department of Biology, The Pennsylvania State University, University Park, Pennsylvania, United States of America
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Li CL, Wang M, Ma XY, Zhang W. NRGA1, a putative mitochondrial pyruvate carrier, mediates ABA regulation of guard cell ion channels and drought stress responses in Arabidopsis. MOLECULAR PLANT 2014; 7:1508-21. [PMID: 24842572 DOI: 10.1093/mp/ssu061] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Abscisic acid (ABA) regulates ion channel activity and stomatal movements in response to drought and other stresses. Here, we show that the Arabidopsis thaliana gene NRGA1 is a putative mitochondrial pyruvate carrier which negatively regulates ABA-induced guard cell signaling. NRGA1 transcript was abundant in the A. thaliana leaf and particularly in the guard cells, and its product was directed to the mitochondria. The heterologous co-expression of NRGA1 and AtMPC1 in yeast complemented a loss-of-function mitochondrial pyruvate carrier (MPC) mutant. The nrga1 loss-of-function mutant was very sensitive to the presence of ABA in the context of stomatal movements, and exhibited a heightened tolerance to drought stress. Disruption of NRGA1 gene resulted in increased ABA inhibition of inward K(+) currents and ABA activation of slow anion currents in guard cells. The nrga1/NRGA1 functional complementation lines restored the mutant's phenotypes. Furthermore, transgenic lines of constitutively overexpressing NRGA1 showed opposite stomatal responses, reduced drought tolerance, and ABA sensitivity of guard cell inward K(+) channel inhibition and anion channel activation. Our findings highlight a putative role for the mitochondrial pyruvate carrier in guard cell ABA signaling in response to drought.
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Affiliation(s)
- Chun-Long Li
- Key Laboratory of Plant Cell Engineering and Germplasm Innovation, Ministry of Education, School of Life Science, Shandong University, Jinan, 250100, China
| | - Mei Wang
- Key Laboratory of Plant Cell Engineering and Germplasm Innovation, Ministry of Education, School of Life Science, Shandong University, Jinan, 250100, China
| | - Xiao-Yan Ma
- Key Laboratory of Plant Cell Engineering and Germplasm Innovation, Ministry of Education, School of Life Science, Shandong University, Jinan, 250100, China
| | - Wei Zhang
- Key Laboratory of Plant Cell Engineering and Germplasm Innovation, Ministry of Education, School of Life Science, Shandong University, Jinan, 250100, China
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Ronzier E, Corratgé-Faillie C, Sanchez F, Prado K, Brière C, Leonhardt N, Thibaud JB, Xiong TC. CPK13, a noncanonical Ca2+-dependent protein kinase, specifically inhibits KAT2 and KAT1 shaker K+ channels and reduces stomatal opening. PLANT PHYSIOLOGY 2014; 166:314-26. [PMID: 25037208 PMCID: PMC4149717 DOI: 10.1104/pp.114.240226] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2014] [Accepted: 07/15/2014] [Indexed: 05/18/2023]
Abstract
Ca(2) (+)-dependent protein kinases (CPKs) form a large family of 34 genes in Arabidopsis (Arabidopsis thaliana). Based on their dependence on Ca(2+), CPKs can be sorted into three types: strictly Ca(2+)-dependent CPKs, Ca(2+)-stimulated CPKs (with a significant basal activity in the absence of Ca(2+)), and essentially calcium-insensitive CPKs. Here, we report on the third type of CPK, CPK13, which is expressed in guard cells but whose role is still unknown. We confirm the expression of CPK13 in Arabidopsis guard cells, and we show that its overexpression inhibits light-induced stomatal opening. We combine several approaches to identify a guard cell-expressed target. We provide evidence that CPK13 (1) specifically phosphorylates peptide arrays featuring Arabidopsis K(+) Channel KAT2 and KAT1 polypeptides, (2) inhibits KAT2 and/or KAT1 when expressed in Xenopus laevis oocytes, and (3) closely interacts in plant cells with KAT2 channels (Förster resonance energy transfer-fluorescence lifetime imaging microscopy). We propose that CPK13 reduces stomatal aperture through its inhibition of the guard cell-expressed KAT2 and KAT1 channels.
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Affiliation(s)
- Elsa Ronzier
- Institut National de la Recherche Agronomique, Unité Mixte de Recherche 386, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 5004, SupAgro, and Université Montpellier 2, Laboratoire de Biochimie & Physiologie Moléculaire des Plantes, F-34060 Montpellier cedex 2, France (E.R., C.C.-F., F.S., K.P., J.-B.T., T.C.X.);Centre National de la Recherche Scientifique, Unité Mixte de Recherche 5546, Laboratoire de Recherche en Sciences Végétales, 31326 Castanet-Tolosan, France (C.B.);Université Paul Sabatier, Pôle de Biotechnologies Végétales 24, Chemin de Borde Rouge, Boite Postale 42617 Auzeville, 31326 Castanet-Tolosan, France (C.B.); andLaboratoire de Biologie du Développement des Plantes, Unité Mixte de Recherche 7265 Centre National de la Recherche Scientifique-Commissariat à l'Energie Atomique-Université Aix-Marseille II, Commissariat à l'Energie Atomique Cadarache Bat 156, 13108 St. Paul Lez Durance, France (N.L.)
| | - Claire Corratgé-Faillie
- Institut National de la Recherche Agronomique, Unité Mixte de Recherche 386, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 5004, SupAgro, and Université Montpellier 2, Laboratoire de Biochimie & Physiologie Moléculaire des Plantes, F-34060 Montpellier cedex 2, France (E.R., C.C.-F., F.S., K.P., J.-B.T., T.C.X.);Centre National de la Recherche Scientifique, Unité Mixte de Recherche 5546, Laboratoire de Recherche en Sciences Végétales, 31326 Castanet-Tolosan, France (C.B.);Université Paul Sabatier, Pôle de Biotechnologies Végétales 24, Chemin de Borde Rouge, Boite Postale 42617 Auzeville, 31326 Castanet-Tolosan, France (C.B.); andLaboratoire de Biologie du Développement des Plantes, Unité Mixte de Recherche 7265 Centre National de la Recherche Scientifique-Commissariat à l'Energie Atomique-Université Aix-Marseille II, Commissariat à l'Energie Atomique Cadarache Bat 156, 13108 St. Paul Lez Durance, France (N.L.)
| | - Frédéric Sanchez
- Institut National de la Recherche Agronomique, Unité Mixte de Recherche 386, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 5004, SupAgro, and Université Montpellier 2, Laboratoire de Biochimie & Physiologie Moléculaire des Plantes, F-34060 Montpellier cedex 2, France (E.R., C.C.-F., F.S., K.P., J.-B.T., T.C.X.);Centre National de la Recherche Scientifique, Unité Mixte de Recherche 5546, Laboratoire de Recherche en Sciences Végétales, 31326 Castanet-Tolosan, France (C.B.);Université Paul Sabatier, Pôle de Biotechnologies Végétales 24, Chemin de Borde Rouge, Boite Postale 42617 Auzeville, 31326 Castanet-Tolosan, France (C.B.); andLaboratoire de Biologie du Développement des Plantes, Unité Mixte de Recherche 7265 Centre National de la Recherche Scientifique-Commissariat à l'Energie Atomique-Université Aix-Marseille II, Commissariat à l'Energie Atomique Cadarache Bat 156, 13108 St. Paul Lez Durance, France (N.L.)
| | - Karine Prado
- Institut National de la Recherche Agronomique, Unité Mixte de Recherche 386, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 5004, SupAgro, and Université Montpellier 2, Laboratoire de Biochimie & Physiologie Moléculaire des Plantes, F-34060 Montpellier cedex 2, France (E.R., C.C.-F., F.S., K.P., J.-B.T., T.C.X.);Centre National de la Recherche Scientifique, Unité Mixte de Recherche 5546, Laboratoire de Recherche en Sciences Végétales, 31326 Castanet-Tolosan, France (C.B.);Université Paul Sabatier, Pôle de Biotechnologies Végétales 24, Chemin de Borde Rouge, Boite Postale 42617 Auzeville, 31326 Castanet-Tolosan, France (C.B.); andLaboratoire de Biologie du Développement des Plantes, Unité Mixte de Recherche 7265 Centre National de la Recherche Scientifique-Commissariat à l'Energie Atomique-Université Aix-Marseille II, Commissariat à l'Energie Atomique Cadarache Bat 156, 13108 St. Paul Lez Durance, France (N.L.)
| | - Christian Brière
- Institut National de la Recherche Agronomique, Unité Mixte de Recherche 386, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 5004, SupAgro, and Université Montpellier 2, Laboratoire de Biochimie & Physiologie Moléculaire des Plantes, F-34060 Montpellier cedex 2, France (E.R., C.C.-F., F.S., K.P., J.-B.T., T.C.X.);Centre National de la Recherche Scientifique, Unité Mixte de Recherche 5546, Laboratoire de Recherche en Sciences Végétales, 31326 Castanet-Tolosan, France (C.B.);Université Paul Sabatier, Pôle de Biotechnologies Végétales 24, Chemin de Borde Rouge, Boite Postale 42617 Auzeville, 31326 Castanet-Tolosan, France (C.B.); andLaboratoire de Biologie du Développement des Plantes, Unité Mixte de Recherche 7265 Centre National de la Recherche Scientifique-Commissariat à l'Energie Atomique-Université Aix-Marseille II, Commissariat à l'Energie Atomique Cadarache Bat 156, 13108 St. Paul Lez Durance, France (N.L.)
| | - Nathalie Leonhardt
- Institut National de la Recherche Agronomique, Unité Mixte de Recherche 386, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 5004, SupAgro, and Université Montpellier 2, Laboratoire de Biochimie & Physiologie Moléculaire des Plantes, F-34060 Montpellier cedex 2, France (E.R., C.C.-F., F.S., K.P., J.-B.T., T.C.X.);Centre National de la Recherche Scientifique, Unité Mixte de Recherche 5546, Laboratoire de Recherche en Sciences Végétales, 31326 Castanet-Tolosan, France (C.B.);Université Paul Sabatier, Pôle de Biotechnologies Végétales 24, Chemin de Borde Rouge, Boite Postale 42617 Auzeville, 31326 Castanet-Tolosan, France (C.B.); andLaboratoire de Biologie du Développement des Plantes, Unité Mixte de Recherche 7265 Centre National de la Recherche Scientifique-Commissariat à l'Energie Atomique-Université Aix-Marseille II, Commissariat à l'Energie Atomique Cadarache Bat 156, 13108 St. Paul Lez Durance, France (N.L.)
| | - Jean-Baptiste Thibaud
- Institut National de la Recherche Agronomique, Unité Mixte de Recherche 386, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 5004, SupAgro, and Université Montpellier 2, Laboratoire de Biochimie & Physiologie Moléculaire des Plantes, F-34060 Montpellier cedex 2, France (E.R., C.C.-F., F.S., K.P., J.-B.T., T.C.X.);Centre National de la Recherche Scientifique, Unité Mixte de Recherche 5546, Laboratoire de Recherche en Sciences Végétales, 31326 Castanet-Tolosan, France (C.B.);Université Paul Sabatier, Pôle de Biotechnologies Végétales 24, Chemin de Borde Rouge, Boite Postale 42617 Auzeville, 31326 Castanet-Tolosan, France (C.B.); andLaboratoire de Biologie du Développement des Plantes, Unité Mixte de Recherche 7265 Centre National de la Recherche Scientifique-Commissariat à l'Energie Atomique-Université Aix-Marseille II, Commissariat à l'Energie Atomique Cadarache Bat 156, 13108 St. Paul Lez Durance, France (N.L.)
| | - Tou Cheu Xiong
- Institut National de la Recherche Agronomique, Unité Mixte de Recherche 386, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 5004, SupAgro, and Université Montpellier 2, Laboratoire de Biochimie & Physiologie Moléculaire des Plantes, F-34060 Montpellier cedex 2, France (E.R., C.C.-F., F.S., K.P., J.-B.T., T.C.X.);Centre National de la Recherche Scientifique, Unité Mixte de Recherche 5546, Laboratoire de Recherche en Sciences Végétales, 31326 Castanet-Tolosan, France (C.B.);Université Paul Sabatier, Pôle de Biotechnologies Végétales 24, Chemin de Borde Rouge, Boite Postale 42617 Auzeville, 31326 Castanet-Tolosan, France (C.B.); andLaboratoire de Biologie du Développement des Plantes, Unité Mixte de Recherche 7265 Centre National de la Recherche Scientifique-Commissariat à l'Energie Atomique-Université Aix-Marseille II, Commissariat à l'Energie Atomique Cadarache Bat 156, 13108 St. Paul Lez Durance, France (N.L.)
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Véry AA, Nieves-Cordones M, Daly M, Khan I, Fizames C, Sentenac H. Molecular biology of K+ transport across the plant cell membrane: what do we learn from comparison between plant species? JOURNAL OF PLANT PHYSIOLOGY 2014; 171:748-69. [PMID: 24666983 DOI: 10.1016/j.jplph.2014.01.011] [Citation(s) in RCA: 167] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2014] [Accepted: 01/30/2014] [Indexed: 05/20/2023]
Abstract
Cloning and characterizations of plant K(+) transport systems aside from Arabidopsis have been increasing over the past decade, favored by the availability of more and more plant genome sequences. Information now available enables the comparison of some of these systems between species. In this review, we focus on three families of plant K(+) transport systems that are active at the plasma membrane: the Shaker K(+) channel family, comprised of voltage-gated channels that dominate the plasma membrane conductance to K(+) in most environmental conditions, and two families of transporters, the HAK/KUP/KT K(+) transporter family, which includes some high-affinity transporters, and the HKT K(+) and/or Na(+) transporter family, in which K(+)-permeable members seem to be present in monocots only. The three families are briefly described, giving insights into the structure of their members and on functional properties and their roles in Arabidopsis or rice. The structure of the three families is then compared between plant species through phylogenic analyses. Within clusters of ortologues/paralogues, similarities and differences in terms of expression pattern, functional properties and, when known, regulatory interacting partners, are highlighted. The question of the physiological significance of highlighted differences is also addressed.
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Affiliation(s)
- Anne-Aliénor Véry
- Biochimie & Physiologie Moléculaire des Plantes, UMR 5004 CNRS/386 INRA/SupAgro Montpellier/Université Montpellier 2, Campus SupAgro-INRA, 34060 Montpellier Cedex 2, France.
| | - Manuel Nieves-Cordones
- Biochimie & Physiologie Moléculaire des Plantes, UMR 5004 CNRS/386 INRA/SupAgro Montpellier/Université Montpellier 2, Campus SupAgro-INRA, 34060 Montpellier Cedex 2, France
| | - Meriem Daly
- Biochimie & Physiologie Moléculaire des Plantes, UMR 5004 CNRS/386 INRA/SupAgro Montpellier/Université Montpellier 2, Campus SupAgro-INRA, 34060 Montpellier Cedex 2, France; Laboratoire d'Ecologie et d'Environnement, Faculté des Sciences Ben M'sik, Université Hassan II-Mohammedia, Avenue Cdt Driss El Harti, BP 7955, Sidi Othmane, Casablanca, Morocco
| | - Imran Khan
- Biochimie & Physiologie Moléculaire des Plantes, UMR 5004 CNRS/386 INRA/SupAgro Montpellier/Université Montpellier 2, Campus SupAgro-INRA, 34060 Montpellier Cedex 2, France; Department of Agronomy, University of Agriculture, Faisalabad, Pakistan
| | - Cécile Fizames
- Biochimie & Physiologie Moléculaire des Plantes, UMR 5004 CNRS/386 INRA/SupAgro Montpellier/Université Montpellier 2, Campus SupAgro-INRA, 34060 Montpellier Cedex 2, France
| | - Hervé Sentenac
- Biochimie & Physiologie Moléculaire des Plantes, UMR 5004 CNRS/386 INRA/SupAgro Montpellier/Université Montpellier 2, Campus SupAgro-INRA, 34060 Montpellier Cedex 2, France
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Eisenach C, Papanatsiou M, Hillert EK, Blatt MR. Clustering of the K+ channel GORK of Arabidopsis parallels its gating by extracellular K+. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2014; 78:203-14. [PMID: 24517091 PMCID: PMC4309415 DOI: 10.1111/tpj.12471] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2013] [Revised: 01/18/2014] [Accepted: 01/22/2014] [Indexed: 05/04/2023]
Abstract
GORK is the only outward-rectifying Kv-like K(+) channel expressed in guard cells. Its activity is tightly regulated to facilitate K(+) efflux for stomatal closure and is elevated in ABA in parallel with suppression of the activity of the inward-rectifying K(+) channel KAT1. Whereas the population of KAT1 is subject to regulated traffic to and from the plasma membrane, nothing is known about GORK, its distribution and traffic in vivo. We have used transformations with fluorescently-tagged GORK to explore its characteristics in tobacco epidermis and Arabidopsis guard cells. These studies showed that GORK assembles in puncta that reversibly dissociated as a function of the external K(+) concentration. Puncta dissociation parallelled the gating dependence of GORK, the speed of response consistent with the rapidity of channel gating response to changes in the external ionic conditions. Dissociation was also suppressed by the K(+) channel blocker Ba(2+) . By contrast, confocal and protein biochemical analysis failed to uncover substantial exo- and endocytotic traffic of the channel. Gating of GORK is displaced to more positive voltages with external K(+) , a characteristic that ensures the channel facilitates only K(+) efflux regardless of the external cation concentration. GORK conductance is also enhanced by external K(+) above 1 mm. We suggest that GORK clustering in puncta is related to its gating and conductance, and reflects associated conformational changes and (de)stabilisation of the channel protein, possibly as a platform for transmission and coordination of channel gating in response to external K(+) .
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Affiliation(s)
| | - Maria Papanatsiou
- Laboratory of Plant Physiology and Biophysics, Institute of Molecular, Cell and Systems Biology, University of GlasgowBower Building, Glasgow, G12 8QQ, UK
| | - Ellin-Kristina Hillert
- Laboratory of Plant Physiology and Biophysics, Institute of Molecular, Cell and Systems Biology, University of GlasgowBower Building, Glasgow, G12 8QQ, UK
| | - Michael R Blatt
- Laboratory of Plant Physiology and Biophysics, Institute of Molecular, Cell and Systems Biology, University of GlasgowBower Building, Glasgow, G12 8QQ, UK
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29
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Felle HH. Ion-selective Microelectrodes: Their Use and Importance in Modern Plant Cell Biology. ACTA ACUST UNITED AC 2014. [DOI: 10.1111/j.1438-8677.1993.tb00331.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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31
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Beffagna N, Romani G, Gatti L. Changes in Chloride Fluxes and Cytosolic pH Induced by Abscisic Acid inElodea densaLeaves. ACTA ACUST UNITED AC 2014. [DOI: 10.1111/j.1438-8677.1995.tb00834.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Venegoni A, Moroni A, Gazzarrini S, Marrè MT. Ammonium and Methylammonium Transport inEgeria densaLeaves in Conditions of Different H+Pump Activity. ACTA ACUST UNITED AC 2014. [DOI: 10.1111/j.1438-8677.1997.tb00652.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Wang Y, Chen ZH, Zhang B, Hills A, Blatt MR. PYR/PYL/RCAR abscisic acid receptors regulate K+ and Cl- channels through reactive oxygen species-mediated activation of Ca2+ channels at the plasma membrane of intact Arabidopsis guard cells. PLANT PHYSIOLOGY 2013; 163:566-77. [PMID: 23899646 PMCID: PMC3793038 DOI: 10.1104/pp.113.219758] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2013] [Accepted: 07/25/2013] [Indexed: 05/17/2023]
Abstract
The discovery of the START family of abscisic acid (ABA) receptors places these proteins at the front of a protein kinase/phosphatase signal cascade that promotes stomatal closure. The connection of these receptors to Ca(2+) signals evoked by ABA has proven more difficult to resolve, although it has been implicated by studies of the pyrbactin-insensitive pyr1/pyl1/pyl2/pyl4 quadruple mutant. One difficulty is that flux through plasma membrane Ca(2+) channels and Ca(2+) release from endomembrane stores coordinately elevate cytosolic free Ca(2+) concentration ([Ca(2+)]i) in guard cells, and both processes are facilitated by ABA. Here, we describe a method for recording Ca(2+) channels at the plasma membrane of intact guard cells of Arabidopsis (Arabidopsis thaliana). We have used this method to resolve the loss of ABA-evoked Ca(2+) channel activity at the plasma membrane in the pyr1/pyl1/pyl2/pyl4 mutant and show the consequent suppression of [Ca(2+)]i increases in vivo. The basal activity of Ca(2+) channels was not affected in the mutant; raising the concentration of Ca(2+) outside was sufficient to promote Ca(2+) entry, to inactivate current carried by inward-rectifying K(+) channels and to activate current carried by the anion channels, both of which are sensitive to [Ca(2+)]i elevations. However, the ABA-dependent increase in reactive oxygen species (ROS) was impaired. Adding the ROS hydrogen peroxide was sufficient to activate the Ca(2+) channels and trigger stomatal closure in the mutant. These results offer direct evidence of PYR/PYL/RCAR receptor coupling to the activation by ABA of plasma membrane Ca(2+) channels through ROS, thus affecting [Ca(2+)]i and its regulation of stomatal closure.
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Affiliation(s)
| | | | - Ben Zhang
- Laboratory of Plant Physiology and Biophysics, University of Glasgow, Glasgow G12 8QQ, United Kingdom (Y.W., Z.-H.C., B.Z., A.H., M.R.B.); and
- School of Natural Sciences, University of Western Sydney, Hawkesbury Campus, Richmond, New South Wales 2753, Australia (Z.-H.C.)
| | - Adrian Hills
- Laboratory of Plant Physiology and Biophysics, University of Glasgow, Glasgow G12 8QQ, United Kingdom (Y.W., Z.-H.C., B.Z., A.H., M.R.B.); and
- School of Natural Sciences, University of Western Sydney, Hawkesbury Campus, Richmond, New South Wales 2753, Australia (Z.-H.C.)
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Yin Y, Adachi Y, Ye W, Hayashi M, Nakamura Y, Kinoshita T, Mori IC, Murata Y. Difference in abscisic acid perception mechanisms between closure induction and opening inhibition of stomata. PLANT PHYSIOLOGY 2013; 163:600-10. [PMID: 23946352 PMCID: PMC3793041 DOI: 10.1104/pp.113.223826] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2013] [Accepted: 08/12/2013] [Indexed: 05/19/2023]
Abstract
Abscisic acid (ABA) induces stomatal closure and inhibits light-induced stomatal opening. The mechanisms in these two processes are not necessarily the same. It has been postulated that the ABA receptors involved in opening inhibition are different from those involved in closure induction. Here, we provide evidence that four recently identified ABA receptors (PYRABACTIN RESISTANCE1 [PYR1], PYRABACTIN RESISTANCE-LIKE1 [PYL1], PYL2, and PYL4) are not sufficient for opening inhibition in Arabidopsis (Arabidopsis thaliana). ABA-induced stomatal closure was impaired in the pyr1/pyl1/pyl2/pyl4 quadruple ABA receptor mutant. ABA inhibition of the opening of the mutant's stomata remained intact. ABA did not induce either the production of reactive oxygen species and nitric oxide or the alkalization of the cytosol in the quadruple mutant, in accordance with the closure phenotype. Whole cell patch-clamp analysis of inward-rectifying K(+) current in guard cells showed a partial inhibition by ABA, indicating that the ABA sensitivity of the mutant was not fully impaired. ABA substantially inhibited blue light-induced phosphorylation of H(+)-ATPase in guard cells in both the mutant and the wild type. On the other hand, in a knockout mutant of the SNF1-related protein kinase, srk2e, stomatal opening and closure, reactive oxygen species and nitric oxide production, cytosolic alkalization, inward-rectifying K(+) current inactivation, and H(+)-ATPase phosphorylation were not sensitive to ABA.
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35
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Ye W, Hossain MA, Munemasa S, Nakamura Y, Mori IC, Murata Y. Endogenous abscisic acid is involved in methyl jasmonate-induced reactive oxygen species and nitric oxide production but not in cytosolic alkalization in Arabidopsis guard cells. JOURNAL OF PLANT PHYSIOLOGY 2013; 170:1212-5. [PMID: 23608742 DOI: 10.1016/j.jplph.2013.03.011] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2013] [Revised: 03/20/2013] [Accepted: 03/21/2013] [Indexed: 05/19/2023]
Abstract
We recently demonstrated that endogenous abscisic acid (ABA) is involved in methyl jasmonate (MeJA)-induced stomatal closure in Arabidopsis thaliana. In this study, we investigated whether endogenous ABA is involved in MeJA-induced reactive oxygen species (ROS) and nitric oxide (NO) production and cytosolic alkalization in guard cells using an ABA-deficient Arabidopsis mutant, aba2-2, and an inhibitor of ABA biosynthesis, fluridon (FLU). The aba2-2 mutation impaired MeJA-induced ROS and NO production. FLU inhibited MeJA-induced ROS production in wild-type guard cells. Pretreatment with 0.1 μM ABA, which does not induce stomatal closure in the wild type, complemented the insensitivity to MeJA of the aba2-2 mutant. However, MeJA induced cytosolic alkalization in both wild-type and aba2-2 guard cells. These results suggest that endogenous ABA is involved in MeJA-induced ROS and NO production but not in MeJA-induced cytosolic alkalization in Arabidopsis guard cells.
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Affiliation(s)
- Wenxiu Ye
- Graduate School of Natural Science and Technology, Okayama University, 1-1-1 Tsushima-Naka, Okayama 700-8530, Japan
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Sharma T, Dreyer I, Riedelsberger J. The role of K(+) channels in uptake and redistribution of potassium in the model plant Arabidopsis thaliana. FRONTIERS IN PLANT SCIENCE 2013; 4:224. [PMID: 23818893 PMCID: PMC3694395 DOI: 10.3389/fpls.2013.00224] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2013] [Accepted: 06/09/2013] [Indexed: 05/17/2023]
Abstract
Potassium (K(+)) is inevitable for plant growth and development. It plays a crucial role in the regulation of enzyme activities, in adjusting the electrical membrane potential and the cellular turgor, in regulating cellular homeostasis and in the stabilization of protein synthesis. Uptake of K(+) from the soil and its transport to growing organs is essential for a healthy plant development. Uptake and allocation of K(+) are performed by K(+) channels and transporters belonging to different protein families. In this review we summarize the knowledge on the versatile physiological roles of plant K(+) channels and their behavior under stress conditions in the model plant Arabidopsis thaliana.
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Affiliation(s)
- Tripti Sharma
- Molecular Biology, Institute for Biochemistry and Biology, University of PotsdamPotsdam, Germany
- IMPRS-PMPG, Max-Planck Institute of Molecular Plant PhysiologyPotsdam, Germany
| | - Ingo Dreyer
- Centro de Biotecnologia y Genomica de Plantas, Universidad Politécnica de MadridMadrid, Spain
- *Correspondence: Ingo Dreyer, Plant Biophysics, Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid, Campus de Montegancedo, Carretera M-40, km 37.7, Pozuelo de Alarcón, Madrid E-28223, Spain e-mail:
| | - Janin Riedelsberger
- Molecular Biology, Institute for Biochemistry and Biology, University of PotsdamPotsdam, Germany
- IMPRS-PMPG, Max-Planck Institute of Molecular Plant PhysiologyPotsdam, Germany
- Janin Riedelsberger, Molecular Biology, Institute for Biochemistry and Biology, University of Potsdam, Karl-Liebknecht-Str. 24/25, House 20, D-14476 Potsdam, Germany e-mail:
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Wang Y, Papanatsiou M, Eisenach C, Karnik R, Williams M, Hills A, Lew VL, Blatt MR. Systems dynamic modeling of a guard cell Cl- channel mutant uncovers an emergent homeostatic network regulating stomatal transpiration. PLANT PHYSIOLOGY 2012; 160:1956-67. [PMID: 23090586 PMCID: PMC3510123 DOI: 10.1104/pp.112.207704] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2012] [Accepted: 10/20/2012] [Indexed: 05/18/2023]
Abstract
Stomata account for much of the 70% of global water usage associated with agriculture and have a profound impact on the water and carbon cycles of the world. Stomata have long been modeled mathematically, but until now, no systems analysis of a plant cell has yielded detail sufficient to guide phenotypic and mutational analysis. Here, we demonstrate the predictive power of a systems dynamic model in Arabidopsis (Arabidopsis thaliana) to explain the paradoxical suppression of channels that facilitate K(+) uptake, slowing stomatal opening, by mutation of the SLAC1 anion channel, which mediates solute loss for closure. The model showed how anion accumulation in the mutant suppressed the H(+) load on the cytosol and promoted Ca(2+) influx to elevate cytosolic pH (pH(i)) and free cytosolic Ca(2+) concentration ([Ca(2+)](i)), in turn regulating the K(+) channels. We have confirmed these predictions, measuring pH(i) and [Ca(2+)](i) in vivo, and report that experimental manipulation of pH(i) and [Ca(2+)](i) is sufficient to recover K(+) channel activities and accelerate stomatal opening in the slac1 mutant. Thus, we uncover a previously unrecognized signaling network that ameliorates the effects of the slac1 mutant on transpiration by regulating the K(+) channels. Additionally, these findings underscore the importance of H(+)-coupled anion transport for pH(i) homeostasis.
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Hills A, Chen ZH, Amtmann A, Blatt MR, Lew VL. OnGuard, a computational platform for quantitative kinetic modeling of guard cell physiology. PLANT PHYSIOLOGY 2012; 159:1026-42. [PMID: 22635116 PMCID: PMC3387691 DOI: 10.1104/pp.112.197244] [Citation(s) in RCA: 127] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2012] [Accepted: 05/20/2012] [Indexed: 05/17/2023]
Abstract
Stomatal guard cells play a key role in gas exchange for photosynthesis while minimizing transpirational water loss from plants by opening and closing the stomatal pore. Foliar gas exchange has long been incorporated into mathematical models, several of which are robust enough to recapitulate transpirational characteristics at the whole-plant and community levels. Few models of stomata have been developed from the bottom up, however, and none are sufficiently generalized to be widely applicable in predicting stomatal behavior at a cellular level. We describe here the construction of computational models for the guard cell, building on the wealth of biophysical and kinetic knowledge available for guard cell transport, signaling, and homeostasis. The OnGuard software was constructed with the HoTSig library to incorporate explicitly all of the fundamental properties for transporters at the plasma membrane and tonoplast, the salient features of osmolite metabolism, and the major controls of cytosolic-free Ca²⁺ concentration and pH. The library engenders a structured approach to tier and interrelate computational elements, and the OnGuard software allows ready access to parameters and equations 'on the fly' while enabling the network of components within each model to interact computationally. We show that an OnGuard model readily achieves stability in a set of physiologically sensible baseline or Reference States; we also show the robustness of these Reference States in adjusting to changes in environmental parameters and the activities of major groups of transporters both at the tonoplast and plasma membrane. The following article addresses the predictive power of the OnGuard model to generate unexpected and counterintuitive outputs.
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Affiliation(s)
| | | | - Anna Amtmann
- Laboratory of Plant Physiology and Biophysics, University of Glasgow, Glasgow G12 8QQ, United Kingdom (A.H., Z.-H.C., A.A., M.R.B.); and Physiological Laboratory, University of Cambridge, Cambridge CB2 3EG, United Kingdom (V.L.L.)
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The pH sensor of the plant K+-uptake channel KAT1 is built from a sensory cloud rather than from single key amino acids. Biochem J 2012; 442:57-63. [DOI: 10.1042/bj20111498] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The uptake of potassium ions (K+) accompanied by an acidification of the apoplasm is a prerequisite for stomatal opening. The acidification (approximately 2–2.5 pH units) is perceived by voltage-gated inward potassium channels (Kin) that then can open their pores with lower energy cost. The sensory units for extracellular pH in stomatal Kin channels are proposed to be histidines exposed to the apoplasm. However, in the Arabidopsis thaliana stomatal Kin channel KAT1, mutations in the unique histidine exposed to the solvent (His267) do not affect the pH dependency. We demonstrate in the present study that His267 of the KAT1 channel cannot sense pH changes since the neighbouring residue Phe266 shifts its pKa to undetectable values through a cation–π interaction. Instead, we show that Glu240 placed in the extracellular loop between transmembrane segments S5 and S6 is involved in the extracellular acid activation mechanism. Based on structural models we propose that this region may serve as a molecular link between the pH- and the voltage-sensor. Like Glu240, several other titratable residues could contribute to the pH-sensor of KAT1, interact with each other and even connect such residues far away from the voltage-sensor with the gating machinery of the channel.
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Rienmüller F, Dreyer I, Schönknecht G, Schulz A, Schumacher K, Nagy R, Martinoia E, Marten I, Hedrich R. Luminal and cytosolic pH feedback on proton pump activity and ATP affinity of V-type ATPase from Arabidopsis. J Biol Chem 2012; 287:8986-93. [PMID: 22215665 DOI: 10.1074/jbc.m111.310367] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Proton pumping of the vacuolar-type H(+)-ATPase into the lumen of the central plant organelle generates a proton gradient of often 1-2 pH units or more. Although structural aspects of the V-type ATPase have been studied in great detail, the question of whether and how the proton pump action is controlled by the proton concentration on both sides of the membrane is not understood. Applying the patch clamp technique to isolated vacuoles from Arabidopsis mesophyll cells in the whole-vacuole mode, we studied the response of the V-ATPase to protons, voltage, and ATP. Current-voltage relationships at different luminal pH values indicated decreasing coupling ratios with acidification. A detailed study of ATP-dependent H(+)-pump currents at a variety of different pH conditions showed a complex regulation of V-ATPase activity by both cytosolic and vacuolar pH. At cytosolic pH 7.5, vacuolar pH changes had relative little effects. Yet, at cytosolic pH 5.5, a 100-fold increase in vacuolar proton concentration resulted in a 70-fold increase of the affinity for ATP binding on the cytosolic side. Changes in pH on either side of the membrane seem to be transferred by the V-ATPase to the other side. A mathematical model was developed that indicates a feedback of proton concentration on peak H(+) current amplitude (v(max)) and ATP consumption (K(m)) of the V-ATPase. It proposes that for efficient V-ATPase function dissociation of transported protons from the pump protein might become higher with increasing pH. This feature results in an optimization of H(+) pumping by the V-ATPase according to existing H(+) concentrations.
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Affiliation(s)
- Florian Rienmüller
- University of Würzburg, Institute for Molecular Plant Physiology and Biophysics, Würzburg, Germany
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Wang Y, Blatt M. Anion channel sensitivity to cytosolic organic acids implicates a central role for oxaloacetate in integrating ion flux with metabolism in stomatal guard cells. Biochem J 2011; 439:161-70. [PMID: 21745184 PMCID: PMC3181827 DOI: 10.1042/bj20110845] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2011] [Revised: 07/01/2011] [Accepted: 07/11/2011] [Indexed: 11/23/2022]
Abstract
Stomatal guard cells play a key role in gas exchange for photosynthesis and in minimizing transpirational water loss from plants by opening and closing the stomatal pore. The bulk of the osmotic content driving stomatal movements depends on ionic fluxes across both the plasma membrane and tonoplast, the metabolism of organic acids, primarily Mal (malate), and its accumulation and loss. Anion channels at the plasma membrane are thought to comprise a major pathway for Mal efflux during stomatal closure, implicating their key role in linking solute flux with metabolism. Nonetheless, little is known of the regulation of anion channel current (I(Cl)) by cytosolic Mal or its immediate metabolite OAA (oxaloacetate). In the present study, we have examined the impact of Mal, OAA and of the monocarboxylic acid anion acetate in guard cells of Vicia faba L. and report that all three organic acids affect I(Cl), but with markedly different characteristics and sidedness to their activities. Most prominent was a suppression of ICl by OAA within the physiological range of concentrations found in vivo. These findings indicate a capacity for OAA to co-ordinate organic acid metabolism with I(Cl) through the direct effect of organic acid pool size. The findings of the present study also add perspective to in vivo recordings using acetate-based electrolytes.
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Affiliation(s)
- Yizhou Wang
- Laboratory of Plant Physiology and Biophysics, Institute of Molecular Cell and Systems Biology, Bower Building, University of Glasgow, Glasgow G12 8QQ, U.K
| | - Michael R. Blatt
- Laboratory of Plant Physiology and Biophysics, Institute of Molecular Cell and Systems Biology, Bower Building, University of Glasgow, Glasgow G12 8QQ, U.K
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Lager I, Andréasson O, Dunbar T, Andreasson E, Escobar MA, Rasmusson AG. Changes in external pH rapidly alter plant gene expression and modulate auxin and elicitor responses. PLANT, CELL & ENVIRONMENT 2010; 33:1513-28. [PMID: 20444216 PMCID: PMC2920358 DOI: 10.1111/j.1365-3040.2010.02161.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
pH is a highly variable environmental factor for the root, and plant cells can modify apoplastic pH for nutrient acquisition and in response to extracellular signals. Nevertheless, surprisingly few effects of external pH on plant gene expression have been reported. We have used microarrays to investigate whether external pH affects global gene expression. In Arabidopsis thaliana roots, 881 genes displayed at least twofold changes in transcript abundance 8 h after shifting medium pH from 6.0 to 4.5, identifying pH as a major affector of global gene expression. Several genes responded within 20 min, and gene responses were also observed in leaves of seedling cultures. The pH 4.5 treatment was not associated with abiotic stress, as evaluated from growth and transcriptional response. However, the observed patterns of global gene expression indicated redundancies and interactions between the responses to pH, auxin and pathogen elicitors. In addition, major shifts in gene expression were associated with cell wall modifications and Ca(2+) signalling. Correspondingly, a marked overrepresentation of Ca(2+)/calmodulin-associated motifs was observed in the promoters of pH-responsive genes. This strongly suggests that plant pH recognition involves intracellular Ca(2+). Overall, the results emphasize the previously underappreciated role of pH in plant responses to the environment.
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Affiliation(s)
- Ida Lager
- Department of Biology, Lund University, SE-22362, Lund, Sweden (I.L., O.A., E.A., A.G.R.); Department of Biological Sciences, California State University San Marcos, San Marcos, CA 92096, USA (T.B., M.A.E.)
| | - Ola Andréasson
- Department of Biology, Lund University, SE-22362, Lund, Sweden (I.L., O.A., E.A., A.G.R.); Department of Biological Sciences, California State University San Marcos, San Marcos, CA 92096, USA (T.B., M.A.E.)
| | - Tiffany Dunbar
- Department of Biology, Lund University, SE-22362, Lund, Sweden (I.L., O.A., E.A., A.G.R.); Department of Biological Sciences, California State University San Marcos, San Marcos, CA 92096, USA (T.B., M.A.E.)
| | - Erik Andreasson
- Department of Biology, Lund University, SE-22362, Lund, Sweden (I.L., O.A., E.A., A.G.R.); Department of Biological Sciences, California State University San Marcos, San Marcos, CA 92096, USA (T.B., M.A.E.)
| | - Matthew A. Escobar
- Department of Biology, Lund University, SE-22362, Lund, Sweden (I.L., O.A., E.A., A.G.R.); Department of Biological Sciences, California State University San Marcos, San Marcos, CA 92096, USA (T.B., M.A.E.)
| | - Allan G. Rasmusson
- Department of Biology, Lund University, SE-22362, Lund, Sweden (I.L., O.A., E.A., A.G.R.); Department of Biological Sciences, California State University San Marcos, San Marcos, CA 92096, USA (T.B., M.A.E.)
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Wippel K, Wittek A, Hedrich R, Sauer N. Inverse pH regulation of plant and fungal sucrose transporters: a mechanism to regulate competition for sucrose at the host/pathogen interface? PLoS One 2010; 5:e12429. [PMID: 20865151 PMCID: PMC2928750 DOI: 10.1371/journal.pone.0012429] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2010] [Accepted: 08/04/2010] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Plant sucrose transporter activities were shown to respond to changes in the extracellular pH and redox status, and oxidizing compounds like glutathione (GSSG) or H(2)O(2) were reported to effect the subcellular targeting of these proteins. We hypothesized that changes in both parameters might be used to modulate the activities of competing sucrose transporters at a plant/pathogen interface. We, therefore, compared the effects of redox-active compounds and of extracellular pH on the sucrose transporters UmSRT1 and ZmSUT1 known to compete for extracellular sucrose in the Ustilago maydis (corn smut)/Zea mays (maize) pathosystem. METHODOLOGY/PRINCIPAL FINDINGS We present functional analyses of the U. maydis sucrose transporter UmSRT1 and of the plant sucrose transporters ZmSUT1 and StSUT1 in Saccharomyces cerevisiae or in Xenopus laevis oocytes in the presence of different extracellular pH-values and redox systems, and study the possible effects of these treatments on the subcellular targeting. We observed an inverse regulation of host and pathogen sucrose transporters by changes in the apoplastic pH. Under none of the conditions analyzed, we could confirm the reported effects of redox-active compounds. CONCLUSIONS/SIGNIFICANCE Our data suggest that changes in the extracellular pH but not of the extracellular redox status might be used to oppositely adjust the transport activities of plant and fungal sucrose transporters at the host/pathogen interface.
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Affiliation(s)
- Kathrin Wippel
- Molekulare Pflanzenphysiologie, Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Anke Wittek
- Molekulare Pflanzenphysiologie und Biophysik, Julius-von-Sachs-Institut, Biozentrum, Universität Würzburg, Würzburg, Germany
| | - Rainer Hedrich
- Molekulare Pflanzenphysiologie und Biophysik, Julius-von-Sachs-Institut, Biozentrum, Universität Würzburg, Würzburg, Germany
| | - Norbert Sauer
- Molekulare Pflanzenphysiologie, Universität Erlangen-Nürnberg, Erlangen, Germany
- * E-mail:
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Chen ZH, Hills A, Lim CK, Blatt MR. Dynamic regulation of guard cell anion channels by cytosolic free Ca2+ concentration and protein phosphorylation. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2010; 61:816-25. [PMID: 20015065 DOI: 10.1111/j.1365-313x.2009.04108.x] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
In guard cells, activation of anion channels (I(anion)) is an early event leading to stomatal closure. Activation of I(anion) has been associated with abscisic acid (ABA) and its elevation of the cytosolic free Ca(2+) concentration ([Ca(2+)](i)). However, the dynamics of the action of [Ca(2+)](i) on I(anion) has never been established, despite its importance for understanding the mechanics of stomatal adaptation to stress. We have quantified the [Ca(2+)](i) dynamics of I(anion) in Vicia faba guard cells, measuring channel current under a voltage clamp while manipulating and recording [Ca(2+)](i) using Fura-2 fluorescence imaging. We found that I(anion) rises with [Ca(2+)](i) only at concentrations substantially above the mean resting value of 125 +/- 13 nm, yielding an apparent K(d) of 720 +/- 65 nm and a Hill coefficient consistent with the binding of three to four Ca(2+) ions to activate the channels. Approximately 30% of guard cells exhibited a baseline of I(anion) activity, but without a dependence of the current on [Ca(2+)](i). The protein phosphatase antagonist okadaic acid increased this current baseline over twofold. Additionally, okadaic acid altered the [Ca(2+)](i) sensitivity of I(anion), displacing the apparent K(d) for [Ca(2+)](i) to 573 +/- 38 nm. These findings support previous evidence for different modes of regulation for I(anion), only one of which depends on [Ca(2+)](i), and they underscore an independence of [Ca(2+)](i) from protein (de-)phosphorylation in controlling I(anion). Most importantly, our results demonstrate a significant displacement of I(anion) sensitivity to higher [Ca(2+)](i) compared with that of the guard cell K(+) channels, implying a capacity for variable dynamics between net osmotic solute uptake and loss.
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Affiliation(s)
- Zhong-Hua Chen
- Laboratory of Plant Physiology and Biophysics, Plant Sciences Research Group, Faculty of Biomedical and Life Sciences, Bower Building, Glasgow G12 8QQ, UK
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Sukhov V, Vodeneev V. A mathematical model of action potential in cells of vascular plants. J Membr Biol 2009; 232:59-67. [PMID: 19921324 DOI: 10.1007/s00232-009-9218-9] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2009] [Accepted: 10/23/2009] [Indexed: 11/30/2022]
Abstract
A mathematical model of action potential (AP) in vascular plants cells has been worked out. The model takes into account actions of plasmalemma ion transport systems (K(+), Cl(-) and Ca(2+) channels; H(+)- and Ca(2+)-ATPases; 2H(+)/Cl(-) symporter; and H(+)/K(+) antiporter), changes of ion concentrations in the cell and in the extracellular space, cytoplasmic and apoplastic buffer capacities and the temperature dependence of active transport systems. The model of AP simulates a stationary level of the membrane potential and ion concentrations, generation of AP induced by electrical stimulation and gradual cooling and the impact of external Ca(2+) for AP development. The model supports a hypothesis about participation of H(+)-ATPase in AP generation.
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Affiliation(s)
- Vladimir Sukhov
- Department of Biophysics, N.I. Lobachevsky State University of Nizhny Novgorod, Gagarin Avenue, 23, Nizhny Novgorod 603950, Russia.
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Monshausen GB, Bibikova TN, Weisenseel MH, Gilroy S. Ca2+ regulates reactive oxygen species production and pH during mechanosensing in Arabidopsis roots. THE PLANT CELL 2009; 21:2341-56. [PMID: 19654264 PMCID: PMC2751959 DOI: 10.1105/tpc.109.068395] [Citation(s) in RCA: 265] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2009] [Revised: 06/25/2009] [Accepted: 07/14/2009] [Indexed: 05/17/2023]
Abstract
Mechanical stimulation of plants triggers a cytoplasmic Ca(2+) increase that is thought to link the touch stimulus to appropriate growth responses. We found that in roots of Arabidopsis thaliana, external and endogenously generated mechanical forces consistently trigger rapid and transient increases in cytosolic Ca(2+) and that the signatures of these Ca(2+) transients are stimulus specific. Mechanical stimulation likewise elicited an apoplastic alkalinization and cytoplasmic acidification as well as apoplastic reactive oxygen species (ROS) production. These responses showed the same kinetics as mechanically induced Ca(2+) transients and could be elicited in the absence of a mechanical stimulus by artificially increasing Ca(2+) concentrations. Both pH changes and ROS production were inhibited by pretreatment with a Ca(2+) channel blocker, which also inhibited mechanically induced elevations in cytosolic Ca(2+). In trichoblasts of the Arabidopsis root hair defective2 mutant, which lacks a functional NADPH oxidase RBOH C, touch stimulation still triggered pH changes but not the local increase in ROS production seen in wild-type plants. Thus, mechanical stimulation likely elicits Ca(2+)-dependent activation of RBOH C, resulting in ROS production to the cell wall. This ROS production appears to be coordinated with intra- and extracellular pH changes through the same mechanically induced cytosolic Ca(2+) transient.
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Szczerba MW, Britto DT, Kronzucker HJ. K+ transport in plants: physiology and molecular biology. JOURNAL OF PLANT PHYSIOLOGY 2009; 166:447-66. [PMID: 19217185 DOI: 10.1016/j.jplph.2008.12.009] [Citation(s) in RCA: 111] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2008] [Revised: 11/10/2008] [Accepted: 12/10/2008] [Indexed: 05/06/2023]
Abstract
Potassium (K(+)) is an essential nutrient and the most abundant cation in plant cells. Plants have a wide variety of transport systems for K(+) acquisition, catalyzing K(+) uptake across a wide spectrum of external concentrations, and mediating K(+) movement within the plant as well as its efflux into the environment. K(+) transport responds to variations in external K(+) supply, to the presence of other ions in the root environment, and to a range of plant stresses, via Ca(2+) signaling cascades and regulatory proteins. This review will summarize the molecular identities of known K(+) transporters, and examine how this information supports physiological investigations of K(+) transport and studies of plant stress responses in a changing environment.
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Affiliation(s)
- Mark W Szczerba
- Department of Plant Sciences, University of California, Davis, 1 Shields Ave., Davis, CA 95616, USA.
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Harada A, Shimazaki KI. Measurement of changes in cytosolic Ca2+ in Arabidopsis guard cells and mesophyll cells in response to blue light. PLANT & CELL PHYSIOLOGY 2009; 50:360-73. [PMID: 19106118 DOI: 10.1093/pcp/pcn203] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Phototropins (phot1 and phot2) are blue light (BL) receptors that mediate responses including phototropism, chloroplast movement and stomatal opening, and increased cytosolic Ca(2+). BL absorbed by phototropins activates plasma membrane H(+)-ATPase in guard cells, resulting in membrane hyperpolarization, and drives K(+) uptake and stomatal opening. However, it is unclear whether the phototropin-mediated Ca(2+) increase activates the H(+)-ATPase. Here, we determined cytosolic Ca(2+) concentrations in guard cell protoplasts (GCPs) from Arabidopsis transformed with aequorin. Cytosolic Ca(2+) increased rapidly in response to BL in GCPs from both the wild type and phot1 phot2 double mutants, but was mostly suppressed by an inhibitor of photosynthetic electron flow (DCMU). With depleted external K(+), we observed another slower Ca(2+) increase, which was phototropin- dependent. Fusicoccin, a H(+)-ATPase activator, mimicked the effect of BL. The slow Ca(2+) increase thus appears to result from membrane hyperpolarization. The slow Ca(2+) increase was suppressed by external K(+) and was restored by blockers of inward-rectifying K(+) channels, CsCl and tetraethylammonium, suggesting the preferential uptake of K(+) over Ca(2+). Such efficient K(+) uptake in response to BL was not found in mesophyll cells. Both the fast and the slow Ca(2+) increases were inhibited by Ca(2+) channel blockers (CoCl(2) and LaCl(3)) and a chelating agent (EGTA). These results indicate that the phototropin-mediated Ca(2+) increase was not observed prior to H(+)-ATPase activation in guard cells and that Ca(2+) entered guard cells via Ca(2+) channels through photosynthesis and phototropin-mediated membrane hyperpolarization.
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Affiliation(s)
- Akiko Harada
- Department of Biology, Kyushu University, Fukuoka, Japan.
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Sirichandra C, Wasilewska A, Vlad F, Valon C, Leung J. The guard cell as a single-cell model towards understanding drought tolerance and abscisic acid action. JOURNAL OF EXPERIMENTAL BOTANY 2009; 60:1439-63. [PMID: 19181866 DOI: 10.1093/jxb/ern340] [Citation(s) in RCA: 121] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Stomatal guard cells are functionally specialized epidermal cells usually arranged in pairs surrounding a pore. Changes in ion fluxes, and more specifically osmolytes, within the guard cells drive opening/closing of the pore, allowing gas exchange while limiting water loss through evapo-transpiration. Adjustments of the pore aperture to optimize these conflicting needs are thus centrally important for land plants to survive, especially with the rise in CO(2) associated with global warming and increasing water scarcity this century. The basic biophysical events in modulating membrane transport have been gradually delineated over two decades. Genetics and molecular approaches in recent years have complemented and extended these earlier studies to identify major regulatory nodes. In Arabidopsis, the reference for guard cell genetics, stomatal opening driven by K(+) entry is mainly through KAT1 and KAT2, two voltage-gated K(+) inward-rectifying channels that are activated on hyperpolarization of the plasma membrane principally by the OST2 H(+)-ATPase (proton pump coupled to ATP hydrolysis). By contrast, stomatal closing is caused by K(+) efflux mainly through GORK, the outward-rectifying channel activated by membrane depolarization. The depolarization is most likely initiated by SLAC1, an anion channel distantly related to the dicarboxylate/malic acid transport protein found in fungi and bacteria. Beyond this established framework, there is also burgeoning evidence for the involvement of additional transporters, such as homologues to the multi-drug resistance proteins (or ABC transporters) as intimated by several pharmacological and reverse genetics studies. General inhibitors of protein kinases and protein phosphatases have been shown to profoundly affect guard cell membrane transport properties. Indeed, the first regulatory enzymes underpinning these transport processes revealed genetically were several protein phosphatases of the 2C class and the OST1 kinase, a member of the SnRK2 family. Taken together, these results are providing the first glimpses of an emerging signalling complex critical for modulating the stomatal aperture in response to environmental stimuli.
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Affiliation(s)
- Caroline Sirichandra
- Institut des Sciences du Végetal, Centre National de la Recherche Scientifique, Gif-sur-Yvette, France
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