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cGMP-dependent ABA-induced stomatal closure in the ABA-insensitive Arabidopsis mutant abi1-1

Research output: Contribution to journalJournal article

Published

Journal publication date07/2011
JournalNew Phytologist
Journal number1
Volume191
Number of pages13
Pages57-69
Original languageEnglish

Abstract

The drought hormone abscisic acid (ABA) is widely known to produce reductions in stomatal aperture in guard cells. The second messenger cyclic guanosine 3', 5'-monophosphate (cGMP) is thought to form part of the signalling pathway by which ABA induces stomatal closure.

We have examined the signalling events during cGMP-dependent ABA-induced stomatal closure in wild-type Arabidopsis plants and plants of the ABA-insensitive Arabidopsis mutant abi1-1.

We show that cGMP acts downstream of hydrogen peroxide (H2O2) and nitric oxide (NO) in the signalling pathway by which ABA induces stomatal closure. H2O2- and NO-induced increases in the cytosolic free calcium concentration ([Ca2+](cyt)) were cGMP-dependent, positioning cGMP upstream of [Ca2+](cyt), and involved the action of the type 2C protein phosphatase ABI1. Increases in cGMP were mediated through the stimulation of guanylyl cyclase by H2O2 and NO. We identify nucleoside diphosphate kinase as a new cGMP target protein in Arabidopsis.

This study positions cGMP downstream of ABA-induced changes in H2O2 and NO, and upstream of increases in [Ca2+](cyt) in the signalling pathway leading to stomatal closure.