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Nguyen TBA, Lefoulon C, Nguyen TH, Blatt MR, Carroll W. Engineering stomata for enhanced carbon capture and water-use efficiency. TRENDS IN PLANT SCIENCE 2023; 28:1290-1309. [PMID: 37423785 DOI: 10.1016/j.tplants.2023.06.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Revised: 05/29/2023] [Accepted: 06/02/2023] [Indexed: 07/11/2023]
Abstract
Stomatal pores facilitate gaseous exchange between the inner air spaces of the leaf and the atmosphere. As gatekeepers that balance CO2 entry for photosynthesis against transpirational water loss, they are a focal point for efforts to improve crop performance, especially in the efficiency of water use, within the changing global environment. Until recently, engineering strategies had focused on stomatal conductance in the steady state. These strategies are limited by the physical constraints of CO2 and water exchange such that gains in water-use efficiency (WUE) commonly come at a cost in carbon assimilation. Attention to stomatal speed and responsiveness circumvents these constraints and offers alternatives to enhancing WUE that also promise increases in carbon assimilation in the field.
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Affiliation(s)
- Thu Binh-Anh Nguyen
- Laboratory of Plant Physiology and Biophysics, Bower Building, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Cecile Lefoulon
- Laboratory of Plant Physiology and Biophysics, Bower Building, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Thanh-Hao Nguyen
- 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.
| | - William Carroll
- Laboratory of Plant Physiology and Biophysics, Bower Building, University of Glasgow, Glasgow, G12 8QQ, UK
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2
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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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3
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Rawat N, Wungrampha S, Singla-Pareek SL, Yu M, Shabala S, Pareek A. Rewilding staple crops for the lost halophytism: Toward sustainability and profitability of agricultural production systems. MOLECULAR PLANT 2022; 15:45-64. [PMID: 34915209 DOI: 10.1016/j.molp.2021.12.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 12/10/2021] [Accepted: 12/12/2021] [Indexed: 06/14/2023]
Abstract
Abiotic stress tolerance has been weakened during the domestication of all major staple crops. Soil salinity is a major environmental constraint that impacts over half of the world population; however, given the increasing reliance on irrigation and the lack of available freshwater, agriculture in the 21st century will increasingly become saline. Therefore, global food security is critically dependent on the ability of plant breeders to create high-yielding staple crop varieties that will incorporate salinity tolerance traits and account for future climate scenarios. Previously, we have argued that the current agricultural practices and reliance on crops that exclude salt from uptake is counterproductive and environmentally unsustainable, and thus called for a need for a major shift in a breeding paradigm to incorporate some halophytic traits that were present in wild relatives but were lost in modern crops during domestication. In this review, we provide a comprehensive physiological and molecular analysis of the key traits conferring crop halophytism, such as vacuolar Na+ sequestration, ROS desensitization, succulence, metabolic photosynthetic switch, and salt deposition in trichomes, and discuss the strategies for incorporating them into elite germplasm, to address a pressing issue of boosting plant salinity tolerance.
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Affiliation(s)
- Nishtha Rawat
- Stress Physiology and Molecular Biology Lab, School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Silas Wungrampha
- Stress Physiology and Molecular Biology Lab, School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Sneh L Singla-Pareek
- Plant Stress Biology, International Centre for Genetic Engineering and Biotechnology, New Delhi 110067, India
| | - Min Yu
- International Research Centre for Environmental Membrane Biology, Foshan University, Foshan 528000, China
| | - Sergey Shabala
- International Research Centre for Environmental Membrane Biology, Foshan University, Foshan 528000, China; Tasmanian Institute for Agriculture, University of Tasmania, Hobart Tas 7001, Australia.
| | - Ashwani Pareek
- Stress Physiology and Molecular Biology Lab, School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India; National Agri-Food Biotechnology Institute, Mohali 140306, India.
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4
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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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5
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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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6
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Waghmare S, Lefoulon C, Zhang B, Liliekyte E, Donald N, Blatt MR. K + Channel-SEC11 Binding Exchange Regulates SNARE Assembly for Secretory Traffic. PLANT PHYSIOLOGY 2019; 181:1096-1113. [PMID: 31548266 PMCID: PMC6836825 DOI: 10.1104/pp.19.00919] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Accepted: 09/04/2019] [Indexed: 05/04/2023]
Abstract
Cell expansion requires that ion transport and secretory membrane traffic operate in concert. Evidence from Arabidopsis (Arabidopsis thaliana) indicates that such coordination is mediated by physical interactions between subsets of so-called SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) proteins, which drive the final stages of vesicle fusion, and K+ channels, which facilitate uptake of the cation to maintain cell turgor pressure as the cell expands. However, the sequence of SNARE binding with the K+ channels and its interweaving within the events of SNARE complex assembly for exocytosis remains unclear. We have combined protein-protein interaction and electrophysiological analyses to resolve the binding interactions of the hetero-oligomeric associations. We find that the RYxxWE motif, located within the voltage sensor of the K+ channels, is a nexus for multiple SNARE interactions. Of these, K+ channel binding and its displacement of the regulatory protein SEC11 is critical to prime the Qa-SNARE SYP121. Our results indicate a stabilizing role for the Qbc-SNARE SNAP33 in the Qa-SNARE transition to SNARE complex assembly with the R-SNARE VAMP721. They also suggest that, on its own, the R-SNARE enters an anomalous binding mode with the channels, possibly as a fail-safe measure to ensure a correct binding sequence. Thus, we suggest that SYP121 binding to the K+ channels serves the role of a primary trigger to initiate assembly of the secretory machinery for exocytosis.
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Affiliation(s)
- Sakharam Waghmare
- Laboratory of Plant Physiology and Biophysics, Bower Building, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - Cecile Lefoulon
- Laboratory of Plant Physiology and Biophysics, Bower Building, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - Ben Zhang
- Laboratory of Plant Physiology and Biophysics, Bower Building, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - Edita Liliekyte
- Laboratory of Plant Physiology and Biophysics, Bower Building, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - Naomi Donald
- Laboratory of Plant Physiology and Biophysics, Bower Building, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - Michael R Blatt
- Laboratory of Plant Physiology and Biophysics, Bower Building, University of Glasgow, Glasgow G12 8QQ, United Kingdom
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7
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Kodirov SA. Tale of tail current. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2019; 150:78-97. [PMID: 31238048 DOI: 10.1016/j.pbiomolbio.2019.06.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Revised: 05/22/2019] [Accepted: 06/20/2019] [Indexed: 02/07/2023]
Abstract
The largest biomass of channel proteins is located in unicellular organisms and bacteria that have no organs. However, orchestrated bidirectional ionic currents across the cell membrane via the channels are important for the functioning of organs of organisms, and equally concern both fauna or flora. Several ion channels are activated in the course of action potentials. One of the hallmarks of voltage-dependent channels is a 'tail current' - deactivation as observed after prior and sufficient activation predominantly at more depolarized potentials e.g. for Kv while upon hyperpolarization for HCN α subunits. Tail current also reflects the timing of channel closure that is initiated upon termination of stimuli. Finally, deactivation of currents during repolarization could be a selective estimate for given channel as in case of HERG, if dedicated long and more depolarized 'tail pulse' is used. Since from a holding potential of e.g. -70 mV are often a family of outward K+ currents comprising IA and IK are simultaneously activated in native cells.
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Affiliation(s)
- Sodikdjon A Kodirov
- Pavlov Institute of Physiology, Russian Academy of Sciences, Saint Petersburg, Russia; Cardiovascular Division, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, 02115, USA; Almazov Federal Heart, Blood and Endocrinology Centre, Saint Petersburg, 197341, Russia; Institute of Experimental Medicine, I. P. Pavlov Department of Physiology, Russian Academy of Medical Sciences, Saint Petersburg, Russia; Laboratory of Emotions' Neurobiology, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, 02-093, Poland.
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8
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Lefoulon C, Waghmare S, Karnik R, Blatt MR. Gating control and K + uptake by the KAT1 K + channel leaveraged through membrane anchoring of the trafficking protein SYP121. PLANT, CELL & ENVIRONMENT 2018; 41:2668-2677. [PMID: 29940699 PMCID: PMC6220998 DOI: 10.1111/pce.13392] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Revised: 06/19/2018] [Accepted: 06/19/2018] [Indexed: 05/20/2023]
Abstract
Vesicle traffic is tightly coordinated with ion transport for plant cell expansion through physical interactions between subsets of vesicle-trafficking (so-called SNARE) proteins and plasma membrane Kv channels, including the archetypal inward-rectifying K+ channel, KAT1 of Arabidopsis. Ion channels open and close rapidly over milliseconds, whereas vesicle fusion events require many seconds. Binding has been mapped to conserved motifs of both the Kv channels and the SNAREs, but knowledge of the temporal kinetics of their interactions, especially as it might relate to channel gating and its coordination with vesicle fusion remains unclear. Here, we report that the SNARE SYP121 promotes KAT1 gating through a persistent interaction that alters the stability of the channel, both in its open and closed states. We show, too, that SYP121 action on the channel open state requires SNARE anchoring in the plasma membrane. Our findings indicate that SNARE binding confers a conformational bias that encompasses the microscopic kinetics of channel gating, with leverage applied through the SNARE anchor in favour of the open channel.
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Affiliation(s)
- Cécile Lefoulon
- Laboratory of Plant Physiology and Biophysics, Bower BuildingUniversity of GlasgowGlasgowUK
| | - Sakharam Waghmare
- Laboratory of Plant Physiology and Biophysics, Bower BuildingUniversity of GlasgowGlasgowUK
| | - Rucha Karnik
- Laboratory of Plant Physiology and Biophysics, Bower BuildingUniversity of GlasgowGlasgowUK
| | - Michael R. Blatt
- Laboratory of Plant Physiology and Biophysics, Bower BuildingUniversity of GlasgowGlasgowUK
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9
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Böhm J, Messerer M, Müller HM, Scholz-Starke J, Gradogna A, Scherzer S, Maierhofer T, Bazihizina N, Zhang H, Stigloher C, Ache P, Al-Rasheid KAS, Mayer KFX, Shabala S, Carpaneto A, Haberer G, Zhu JK, Hedrich R. Understanding the Molecular Basis of Salt Sequestration in Epidermal Bladder Cells of Chenopodium quinoa. Curr Biol 2018; 28:3075-3085.e7. [PMID: 30245105 DOI: 10.1016/j.cub.2018.08.004] [Citation(s) in RCA: 69] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Revised: 06/20/2018] [Accepted: 08/01/2018] [Indexed: 02/03/2023]
Abstract
Soil salinity is destroying arable land and is considered to be one of the major threats to global food security in the 21st century. Therefore, the ability of naturally salt-tolerant halophyte plants to sequester large quantities of salt in external structures, such as epidermal bladder cells (EBCs), is of great interest. Using Chenopodium quinoa, a pseudo-cereal halophyte of great economic potential, we have shown previously that, upon removal of salt bladders, quinoa becomes salt sensitive. In this work, we analyzed the molecular mechanism underlying the unique salt dumping capabilities of bladder cells in quinoa. The transporters differentially expressed in the EBC transcriptome and functional electrophysiological testing of key EBC transporters in Xenopus oocytes revealed that loading of Na+ and Cl- into EBCs is mediated by a set of tailored plasma and vacuole membrane-based sodium-selective channel and chloride-permeable transporter.
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Affiliation(s)
- Jennifer Böhm
- Tasmanian Institute for Agriculture, College of Science and Engineering, University of Tasmania, Private Bag 54, Hobart, TAS 7001, Australia
| | - Maxim Messerer
- Plant Genome and Systems Biology, Helmholtz Center Munich, Ingolstädter Landstraße 1, 85764 Neuherberg, Germany
| | - Heike M Müller
- Institute for Molecular Plant Physiology and Biophysics, University of Wuerzburg, Julius-von-Sachs Platz 2, 97082 Wuerzburg, Germany
| | - Joachim Scholz-Starke
- Institute of Biophysics, National Research Council (CNR), Via De Marini 6, 16149 Genova, Italy
| | - Antonella Gradogna
- Institute of Biophysics, National Research Council (CNR), Via De Marini 6, 16149 Genova, Italy
| | - Sönke Scherzer
- Institute for Molecular Plant Physiology and Biophysics, University of Wuerzburg, Julius-von-Sachs Platz 2, 97082 Wuerzburg, Germany
| | - Tobias Maierhofer
- Institute for Molecular Plant Physiology and Biophysics, University of Wuerzburg, Julius-von-Sachs Platz 2, 97082 Wuerzburg, Germany
| | - Nadia Bazihizina
- Tasmanian Institute for Agriculture, College of Science and Engineering, University of Tasmania, Private Bag 54, Hobart, TAS 7001, Australia; Department of Agrifood Production and Environmental Sciences, Università degli Studi di Firenze, Viale delle Idee 30, 50019 Sesto Fiorentino, Florence, Italy
| | - Heng Zhang
- Shanghai Center for Plant Stress Biology, and CAS Center for Excellence in Molecular Plant Sciences, 3888 Chenhua Road, Shanghai 201602, China
| | - Christian Stigloher
- Imaging Core Facility, Biocenter, University of Wuerzburg, Am Hubland, 97074 Wuerzburg, Germany
| | - Peter Ache
- Institute for Molecular Plant Physiology and Biophysics, University of Wuerzburg, Julius-von-Sachs Platz 2, 97082 Wuerzburg, Germany
| | - Khaled A S Al-Rasheid
- Zoology Department, College of Science, King Saud University, PO Box 2455, Riyadh 11451, Saudi Arabia
| | - Klaus F X Mayer
- Plant Genome and Systems Biology, Helmholtz Center Munich, Ingolstädter Landstraße 1, 85764 Neuherberg, Germany
| | - Sergey Shabala
- Tasmanian Institute for Agriculture, College of Science and Engineering, University of Tasmania, Private Bag 54, Hobart, TAS 7001, Australia; Department of Horticulture, Foshan University, Foshan 528000, PRC
| | - Armando Carpaneto
- Institute of Biophysics, National Research Council (CNR), Via De Marini 6, 16149 Genova, Italy; Department of Earth, Environment and Life Sciences (DISTAV), University of Genoa, Viale Benedetto XV 5, 16132 Genova, Italy
| | - Georg Haberer
- Plant Genome and Systems Biology, Helmholtz Center Munich, Ingolstädter Landstraße 1, 85764 Neuherberg, Germany.
| | - Jian-Kang Zhu
- Shanghai Center for Plant Stress Biology, and CAS Center for Excellence in Molecular Plant Sciences, 3888 Chenhua Road, Shanghai 201602, China; Department of Horticulture and Landscape Architecture, Purdue University, 625 Agriculture Mall Drive, West Lafayette, IN 47907, USA.
| | - Rainer Hedrich
- Institute for Molecular Plant Physiology and Biophysics, University of Wuerzburg, Julius-von-Sachs Platz 2, 97082 Wuerzburg, Germany.
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10
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Saito S, Hoshi N, Zulkifli L, Widyastuti S, Goshima S, Dreyer I, Uozumi N. Identification of regions responsible for the function of the plant K + channels KAT1 and AKT2 in Saccharomyces cerevisiae and Xenopus laevis oocytes. Channels (Austin) 2017; 11:510-516. [PMID: 28933647 DOI: 10.1080/19336950.2017.1372066] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The Arabidopsis K+ channel KAT1 complements in K+-limited medium the growth of the K+ uptake defective Saccharomyces cerevisiae mutant strain CY162, while another K+ channel, AKT2, does not. To gain insight into the structural basis for this difference, we constructed 12 recombinant chimeric channels from these two genes. When expressed in CY162, only three of these chimeras fully rescued the growth of CY162 under K+-limited conditions. We conclude that the transmembrane core region of KAT1 is important for its activity in S. cerevisiae. This involves not only the pore region but also parts of its voltage-sensor domain.
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Affiliation(s)
- Shunya Saito
- a Department of Biomolecular Engineering , Graduate School of Engineering, Tohoku University , Sendai , Japan
| | - Naomi Hoshi
- a Department of Biomolecular Engineering , Graduate School of Engineering, Tohoku University , Sendai , Japan
| | - Lalu Zulkifli
- a Department of Biomolecular Engineering , Graduate School of Engineering, Tohoku University , Sendai , Japan
| | - Sri Widyastuti
- b Bioscience and Biotechnology Center , Nagoya University , Nagoya , Japan
| | - Shinobu Goshima
- b Bioscience and Biotechnology Center , Nagoya University , Nagoya , Japan
| | - Ingo Dreyer
- c Centro de Bioinformática y Simulación Molecular , Facultad de Ingeniería, Universidad de Talca , Talca , Chile
| | - Nobuyuki Uozumi
- a Department of Biomolecular Engineering , Graduate School of Engineering, Tohoku University , Sendai , Japan
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11
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Abdelaziz ME, Kim D, Ali S, Fedoroff NV, Al-Babili S. The endophytic fungus Piriformospora indica enhances Arabidopsis thaliana growth and modulates Na +/K + homeostasis under salt stress conditions. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2017; 263:107-115. [PMID: 28818365 DOI: 10.1016/j.plantsci.2017.07.006] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Revised: 07/05/2017] [Accepted: 07/08/2017] [Indexed: 05/08/2023]
Abstract
The mutualistic, endophytic fungus Piriformospora indica has been shown to confer biotic and abiotic stress tolerance to host plants. In this study, we investigated the impact of P. indica on the growth of Arabidopsis plants under normal and salt stress conditions. Our results demonstrate that P. indica colonization increases plant biomass, lateral roots density, and chlorophyll content under both conditions. Colonization with P. indica under salt stress was accompanied by a lower Na+/K+ ratio and less pronounced accumulation of anthocyanin, compared to control plants. Moreover, P. indica colonized roots under salt stress showed enhanced transcript levels of the genes encoding the high Affinity Potassium Transporter 1 (HKT1) and the inward-rectifying K+ channels KAT1 and KAT2, which play key roles in regulating Na+ and K+ homeostasis. The effect of P. indica colonization on AtHKT1;1 expression was also confirmed in the Arabidopsis line gl1-HKT:AtHKT1;1 that expresses an additional AtHKT1;1 copy driven by the native promoter. Colonization of the gl1-HKT:AtHKT1;1 by P. indica also increased lateral roots density and led to a better Na+/K+ ratio, which may be attributed to the observed increase in KAT1 and KAT2 transcript levels. Our findings demonstrate that P. indica colonization promotes Arabidopsis growth under salt stress conditions and that this effect is likely caused by modulation of the expression levels of the major Na+ and K+ ion channels, which allows establishing a balanced ion homeostasis of Na+/K+ under salt stress conditions.
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Affiliation(s)
- Mohamed E Abdelaziz
- King Abdullah University of Science and Technology (KAUST), BESE Division, 23955-6900 Thuwal, Saudi Arabia; Faculty of Agriculture, Cairo University, 12613, Giza, Egypt
| | - Dongjin Kim
- King Abdullah University of Science and Technology (KAUST), BESE Division, 23955-6900 Thuwal, Saudi Arabia; Department of Plant Sciences and Plant Pathology, Montana State University, Bozeman, MT 59717, USA
| | - Shawkat Ali
- King Abdullah University of Science and Technology (KAUST), BESE Division, 23955-6900 Thuwal, Saudi Arabia
| | - Nina V Fedoroff
- King Abdullah University of Science and Technology (KAUST), BESE Division, 23955-6900 Thuwal, Saudi Arabia
| | - Salim Al-Babili
- King Abdullah University of Science and Technology (KAUST), BESE Division, 23955-6900 Thuwal, Saudi Arabia.
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12
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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: 177] [Impact Index Per Article: 25.3] [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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Zhang B, Karnik R, Waghmare S, Donald N, Blatt MR. VAMP721 Conformations Unmask an Extended Motif for K+ Channel Binding and Gating Control. PLANT PHYSIOLOGY 2017; 173:536-551. [PMID: 27821719 PMCID: PMC5210753 DOI: 10.1104/pp.16.01549] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Accepted: 11/04/2016] [Indexed: 05/20/2023]
Abstract
Soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins play a major role in membrane fusion and contribute to cell expansion, signaling, and polar growth in plants. The SNARE SYP121 of Arabidopsis thaliana that facilitates vesicle fusion at the plasma membrane also binds with, and regulates, K+ channels already present at the plasma membrane to affect K+ uptake and K+-dependent growth. Here, we report that its cognate partner VAMP721, which assembles with SYP121 to drive membrane fusion, binds to the KAT1 K+ channel via two sites on the protein, only one of which contributes to channel-gating control. Binding to the VAMP721 SNARE domain suppressed channel gating. By contrast, interaction with the amino-terminal longin domain conferred specificity on VAMP721 binding without influencing gating. Channel binding was defined by a linear motif within the longin domain. The SNARE domain is thought to wrap around this structure when not assembled with SYP121 in the SNARE complex. Fluorescence lifetime analysis showed that mutations within this motif, which suppressed channel binding and its effects on gating, also altered the conformational displacement between the VAMP721 SNARE and longin domains. The presence of these two channel-binding sites on VAMP721, one also required for SNARE complex assembly, implies a well-defined sequence of events coordinating K+ uptake and the final stages of vesicle traffic. It suggests that binding begins with VAMP721, and subsequently with SYP121, thereby coordinating K+ channel gating during SNARE assembly and vesicle fusion. Thus, our findings also are consistent with the idea that the K+ channels are nucleation points for SNARE complex assembly.
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Affiliation(s)
- Ben Zhang
- Laboratory of Plant Physiology and Biophysics, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - Rucha Karnik
- Laboratory of Plant Physiology and Biophysics, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - Sakharam Waghmare
- Laboratory of Plant Physiology and Biophysics, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - Naomi Donald
- 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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14
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15
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Karnik R, Waghmare S, Zhang B, Larson E, Lefoulon C, Gonzalez W, Blatt MR. Commandeering Channel Voltage Sensors for Secretion, Cell Turgor, and Volume Control. TRENDS IN PLANT SCIENCE 2017; 22:81-95. [PMID: 27818003 PMCID: PMC5224186 DOI: 10.1016/j.tplants.2016.10.006] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2016] [Revised: 10/06/2016] [Accepted: 10/07/2016] [Indexed: 05/20/2023]
Abstract
Control of cell volume and osmolarity is central to cellular homeostasis in all eukaryotes. It lies at the heart of the century-old problem of how plants regulate turgor, mineral and water transport. Plants use strongly electrogenic H+-ATPases, and the substantial membrane voltages they foster, to drive solute accumulation and generate turgor pressure for cell expansion. Vesicle traffic adds membrane surface and contributes to wall remodelling as the cell grows. Although a balance between vesicle traffic and ion transport is essential for cell turgor and volume control, the mechanisms coordinating these processes have remained obscure. Recent discoveries have now uncovered interactions between conserved subsets of soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins that drive the final steps in secretory vesicle traffic and ion channels that mediate in inorganic solute uptake. These findings establish the core of molecular links, previously unanticipated, that coordinate cellular homeostasis and cell expansion.
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Affiliation(s)
- Rucha Karnik
- Laboratory of Plant Physiology and Biophysics, Bower Building, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Sakharam Waghmare
- Laboratory of Plant Physiology and Biophysics, Bower Building, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Ben Zhang
- Laboratory of Plant Physiology and Biophysics, Bower Building, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Emily Larson
- Laboratory of Plant Physiology and Biophysics, Bower Building, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Cécile Lefoulon
- Laboratory of Plant Physiology and Biophysics, Bower Building, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Wendy Gonzalez
- Centro de Bioinformatica y Simulacion Molecular, Universidad de Talca, Casilla 721, Talca, Chile
| | - Michael R Blatt
- Laboratory of Plant Physiology and Biophysics, Bower Building, University of Glasgow, Glasgow, G12 8QQ, UK.
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16
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Baumeister D, Hertel B, Schroeder I, Gazzarrini S, Kast SM, Van Etten JL, Moroni A, Thiel G. Conversion of an instantaneous activating K + channel into a slow activating inward rectifier. FEBS Lett 2016; 591:295-303. [PMID: 27995608 DOI: 10.1002/1873-3468.12536] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Revised: 12/14/2016] [Accepted: 12/15/2016] [Indexed: 12/27/2022]
Abstract
The miniature channel, Kcv, is a structural equivalent of the pore of all K+ channels. Here, we follow up on a previous observation that a largely voltage-insensitive channel can be converted into a slow activating inward rectifier after extending the outer transmembrane domain by one Ala. This gain of rectification can be rationalized by dynamic salt bridges at the cytosolic entrance to the channel; opening is favored by voltage-sensitive formation of salt bridges and counteracted by their disruption. Such latent voltage sensitivity in the pore could be relevant for the understanding of voltage gating in complex Kv channels.
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Affiliation(s)
- Dirk Baumeister
- Plant Membrane Biophysics, Technical University Darmstadt, Germany
| | - Brigitte Hertel
- Plant Membrane Biophysics, Technical University Darmstadt, Germany
| | - Indra Schroeder
- Plant Membrane Biophysics, Technical University Darmstadt, Germany
| | - Sabrina Gazzarrini
- Department of Biosciences and CNR IBF-Mi, Università degli Studi di Milano, Italy
| | - Stefan M Kast
- Physikalische Chemie III, Technische Universität Dortmund, Germany
| | - James L Van Etten
- Department of Plant Pathology, Nebraska Center for Virology, University of Nebraska Lincoln, NE, USA
| | - Anna Moroni
- Department of Biosciences and CNR IBF-Mi, Università degli Studi di Milano, Italy
| | - Gerhard Thiel
- Plant Membrane Biophysics, Technical University Darmstadt, Germany
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17
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Grefen C, Karnik R, Larson E, Lefoulon C, Wang Y, Waghmare S, Zhang B, Hills A, Blatt MR. A vesicle-trafficking protein commandeers Kv channel voltage sensors for voltage-dependent secretion. NATURE PLANTS 2015; 1:15108. [PMID: 27250541 DOI: 10.1038/nplants.2015.108] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Accepted: 06/29/2015] [Indexed: 06/05/2023]
Abstract
Growth in plants depends on ion transport for osmotic solute uptake and secretory membrane trafficking to deliver material for wall remodelling and cell expansion. The coordination of these processes lies at the heart of the question, unresolved for more than a century, of how plants regulate cell volume and turgor. Here we report that the SNARE protein SYP121 (SYR1/PEN1), which mediates vesicle fusion at the Arabidopsis plasma membrane, binds the voltage sensor domains (VSDs) of K(+) channels to confer a voltage dependence on secretory traffic in parallel with K(+) uptake. VSD binding enhances secretion in vivo subject to voltage, and mutations affecting VSD conformation alter binding and secretion in parallel with channel gating, net K(+) concentration, osmotic content and growth. These results demonstrate a new and unexpected mechanism for secretory control, in which a subset of plant SNAREs commandeer K(+) channel VSDs to coordinate membrane trafficking with K(+) uptake for growth.
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Affiliation(s)
- Christopher Grefen
- Laboratory of Plant Physiology and Biophysics, Bower Building, University of Glasgow, Glasgow G12 8QQ, UK
| | - Rucha Karnik
- Laboratory of Plant Physiology and Biophysics, Bower Building, University of Glasgow, Glasgow G12 8QQ, UK
| | - Emily Larson
- Laboratory of Plant Physiology and Biophysics, Bower Building, University of Glasgow, Glasgow G12 8QQ, UK
| | - Cécile Lefoulon
- Laboratory of Plant Physiology and Biophysics, Bower Building, University of Glasgow, Glasgow G12 8QQ, UK
| | - Yizhou Wang
- Laboratory of Plant Physiology and Biophysics, Bower Building, University of Glasgow, Glasgow G12 8QQ, UK
| | - Sakharam Waghmare
- Laboratory of Plant Physiology and Biophysics, Bower Building, University of Glasgow, Glasgow G12 8QQ, UK
| | - Ben Zhang
- Laboratory of Plant Physiology and Biophysics, Bower Building, University of Glasgow, Glasgow G12 8QQ, UK
| | - Adrian Hills
- 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
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18
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Zhang B, Karnik R, Wang Y, Wallmeroth N, Blatt MR, Grefen C. The Arabidopsis R-SNARE VAMP721 Interacts with KAT1 and KC1 K+ Channels to Moderate K+ Current at the Plasma Membrane. THE PLANT CELL 2015; 27:1697-717. [PMID: 26002867 PMCID: PMC4498211 DOI: 10.1105/tpc.15.00305] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Revised: 04/08/2015] [Accepted: 05/06/2015] [Indexed: 05/04/2023]
Abstract
SNARE (soluble N-ethylmaleimide-sensitive factor protein attachment protein receptor) proteins drive vesicle traffic, delivering membrane and cargo to target sites within the cell and at its surface. They contribute to cell homeostasis, morphogenesis, and pathogen defense. A subset of SNAREs, including the Arabidopsis thaliana SNARE SYP121, are known also to coordinate solute uptake via physical interactions with K(+) channels and to moderate their gating at the plasma membrane. Here, we identify a second subset of SNAREs that interact to control these K(+) channels, but with opposing actions on gating. We show that VAMPs (vesicle-associated membrane proteins), which target vesicles to the plasma membrane, also interact with and suppress the activities of the inward-rectifying K(+) channels KAT1 and KC1. Interactions were evident in yeast split-ubiquitin assays, they were recovered in vivo by ratiometric bimolecular fluorescence complementation, and they were sensitive to mutation of a single residue, Tyr-57, within the longin domain of VAMP721. Interaction was also recovered on exchange of the residue at this site in the homolog VAMP723, which normally localizes to the endoplasmic reticulum and otherwise did not interact. Functional analysis showed reduced channel activity and alterations in voltage sensitivity that are best explained by a physical interaction with the channel gates. These actions complement those of SYP121, a cognate SNARE partner of VAMP721, and lead us to propose that the channel interactions reflect a "hand-off" in channel control between the two SNARE proteins that is woven together with vesicle fusion.
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Affiliation(s)
- Ben Zhang
- Laboratory of Plant Physiology and Biophysics, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - Rucha Karnik
- Laboratory of Plant Physiology and Biophysics, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - Yizhou Wang
- 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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