AUTHOR=Munemasa Shintaro , Muroyama Daichi , Nagahashi Hiroki , Nakamura Yoshimasa , Mori Izumi C., Murata Yoshiyuki 

TITLE=Regulation of reactive oxygen species-mediated abscisic acid signaling in guard cells and drought tolerance by glutathione

JOURNAL=Frontiers in Plant Science

VOLUME=4

YEAR=2013

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2013.00472

DOI=10.3389/fpls.2013.00472

ISSN=1664-462X

ABSTRACT=<p>The phytohormone abscisic acid (ABA) induces stomatal closure in response to drought stress, leading to reduction of transpirational water loss. A thiol tripeptide glutathione (GSH) is an important regulator of cellular redox homeostasis in plants. Although it has been shown that cellular redox state of guard cells controls ABA-mediated stomatal closure, roles of GSH in guard cell ABA signaling were largely unknown. Recently we demonstrated that GSH functions as a negative regulator of ABA signaling in guard cells. In this study we performed more detailed analyses to reveal how GSH regulates guard cell ABA signaling using the GSH-deficient Arabidopsis mutant <italic>cad2-1</italic>. The <italic>cad2-1</italic> mutant exhibited reduced water loss from rosette leaves. Whole-cell current recording using patch clamp technique revealed that the <italic>cad2-1</italic> mutation did not affect ABA regulation of S-type anion channels. We found enhanced activation of Ca<sup>2+</sup> permeable channels by hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>) in <italic>cad2-1</italic> guard cells. The <italic>cad2-1</italic> mutant showed enhanced H<sub>2</sub>O<sub>2</sub>-induced stomatal closure and significant increase of ROS accumulation in whole leaves in response to ABA. Our findings provide a new understanding of guard cell ABA signaling and a new strategy to improve plant drought tolerance.</p>