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Publication Details
AFRICAN RESEARCH NEXUS
SHINING A SPOTLIGHT ON AFRICAN RESEARCH
agricultural and biological sciences
AtALMT12 represents an R-type anion channel required for stomatal movement in Arabidopsis guard cells
Plant Journal, Volume 63, No. 6, Year 2010
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Description
Stomatal pores formed by a pair of guard cells in the leaf epidermis control gas exchange and transpirational water loss. Stomatal closure is mediated by the release of potassium and anions from guard cells. Anion efflux from guard cells involves slow (S-type) and rapid (R-type) anion channels. Recently the SLAC1 gene has been shown to encode the slow, voltage-independent anion channel component in guard cells. In contrast, the R-type channel still awaits identification. Here, we show that AtALMT12, a member of the aluminum activated malate transporter family in Arabidopsis, represents a guard cell R-type anion channel. AtALMT12 is highly expressed in guard cells and is targeted to the plasma membrane. Plants lacking AtALMT12 are impaired in dark- and CO2-induced stomatal closure, as well as in response to the drought-stress hormone abscisic acid. Patch-clamp studies on guard cell protoplasts isolated from atalmt12 mutants revealed reduced R-type currents compared with wild-type plants when malate is present in the bath media. Following expression of AtALMT12 in Xenopus oocytes, voltage-dependent anion currents reminiscent to R-type channels could be activated. In line with the features of the R-type channel, the activity of heterologously expressed AtALMT12 depends on extracellular malate. Thereby this key metabolite and osmolite of guard cells shifts the threshold for voltage activation of AtALMT12 towards more hyperpolarized potentials. R-Type channels, like voltage-dependent cation channels in nerve cells, are capable of transiently depolarizing guard cells, and thus could trigger membrane potential oscillations, action potentials and initiate long-term anion and K+ efflux via SLAC1 and GORK, respectively. © 2010 Blackwell Publishing Ltd.
Authors & Co-Authors
Meyer, Stefan
Switzerland, Zurich
Universität Zürich
Mumm, Patrick
Germany, Wurzburg
Julius-maximilians-universität Würzburg
Imes, Dennis
Germany, Wurzburg
Julius-maximilians-universität Würzburg
Endler, Anne
Switzerland, Zurich
Universität Zürich
Germany, Potsdam
Max Planck Institute of Molecular Plant Physiology
Weder, Barbara
Switzerland, Zurich
Universität Zürich
Al-Rasheid, Khaled A.S.
Saudi Arabia, Riyadh
College of Sciences
Geiger, Dietmar
Germany, Wurzburg
Julius-maximilians-universität Würzburg
Marten, Irene
Germany, Wurzburg
Julius-maximilians-universität Würzburg
Martinoia, Enrico
Switzerland, Zurich
Universität Zürich
Hedrich, Rainer
Germany, Wurzburg
Julius-maximilians-universität Würzburg
Statistics
Citations: 328
Authors: 10
Affiliations: 4
Identifiers
Doi:
10.1111/j.1365-313X.2010.04302.x
ISSN:
09607412
e-ISSN:
1365313X
Research Areas
Environmental
Genetics And Genomics