Wang, Y., Chen, Z., Zhang, B. , Hills, A. and Blatt, M. R. (2013) 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, 163(2), pp. 566-577. (doi: 10.1104/pp.113.219758) (PMID:23899646)
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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<sup>2+</sup> signals evoked by ABA has proven more difficult to resolve, although it has been implicated by studies of the pyrbactin-insensitive <i>pyr1/pyl1/pyl2/pyl4</i> quadruple mutant. One difficulty is that flux through plasma membrane Ca<sup>2+</sup> channels and Ca<sup>2+</sup> release from endomembrane stores coordinately elevate cytosolic free Ca<sup>2+</sup> concentration ([Ca<sup>2+</sup>]<sub>i</sub>) in guard cells, and both processes are facilitated by ABA. Here, we describe a method for recording Ca<sup>2+</sup> 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<sup>2+</sup> channel activity at the plasma membrane in the <i>pyr1/pyl1/pyl2/pyl4</i> mutant and show the consequent suppression of [Ca<sup>2+</sup>]<sub>i</sub> increases in vivo. The basal activity of Ca<sup>2+</sup> channels was not affected in the mutant; raising the concentration of Ca<sup>2+</sup> outside was sufficient to promote Ca<sup>2+</sup> entry, to inactivate current carried by inward-rectifying K<sup>+</sup> channels and to activate current carried by the anion channels, both of which are sensitive to [Ca<sup>2+</sup>]<sub>i</sub> elevations. However, the ABA-dependent increase in reactive oxygen species (ROS) was impaired. Adding the ROS hydrogen peroxide was sufficient to activate the Ca<sup>2+</sup> 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<sup>2+</sup> channels through ROS, thus affecting [Ca<sup>2+</sup>]<sub>i</sub> and its regulation of stomatal closure.
Item Type: | Articles |
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Status: | Published |
Refereed: | Yes |
Glasgow Author(s) Enlighten ID: | Hills, Mr Adrian and Blatt, Professor Michael and Zhang, Dr Ben and Chen, Dr Zhonghua and Wang, Dr Yizhou |
Authors: | Wang, Y., Chen, Z., Zhang, B., Hills, A., and Blatt, M. R. |
College/School: | College of Medical Veterinary and Life Sciences > School of Molecular Biosciences |
Journal Name: | Plant Physiology |
Publisher: | American Society of Plant Biologists |
ISSN: | 0032-0889 |
ISSN (Online): | 1532-2548 |
Copyright Holders: | Copyright © 2013 The Authors |
First Published: | First published in Plant Physiology 163(2):566-577 |
Publisher Policy: | Reproduced under a Creative Commons License |
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