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Abstract

A major environmental signal influencing day-time stomatal aperture is the vapour pressure deficit between the leaf and atmosphere (VPD). In angiosperms, increased VPD triggers biosynthesis of abscisic acid (ABA), prompting rapid stomatal closure. Altered cell turgor has been proposed as the trigger for ABA biosynthesis, but the timing and nature of the genetic signals linking these processes have remained uncertain. We investigated this in Arabidopsis by examining changes induced by a decrease in leaf turgor, simulating a natural increase in VPD. We found that the rate-limiting gene within the de novo ABA biosynthesis pathway, 9-cis-epoxycarotenoid dioxygenase 3 (NCED3), was induced and ABA levels increased within just 5 min of decreased leaf turgor. This rapid induction matches the time-frame for initiation of stomatal closure in response to a doubling in VPD. We further examined Arabidopsis histidine kinase1 (AHK1) as the most likely candidate for the turgor-sensing receptor involved, but found no significant difference between wild-type and an ahk1 null mutant in the induction of ABA-biosynthetic genes, ABA production, or stomatal behaviour. We show that decreased leaf turgor triggers de novo ABA biosynthesis within the time-frame of the stomatal response to VPD, but that AHK1 does not fulfil a critical role as a turgor-sensing receptor within this pathway.

Item Type:	Article
Authors/Creators:	Sussmilch, FC and Brodribb, TJ and McAdam, SAM
Keywords:	ABA, AHK1, leaf turgor, NCED, stomata, turgor sensor, VPD
Journal or Publication Title:	Journal of Experimental Botany
Publisher:	Oxford Univ Press
ISSN:	0022-0957
DOI / ID Number:	10.1093/jxb/erx124
Copyright Information:	Copyright 2017 The Author. Licensed under Creative Commons Attribution 4.0 International (CC BY 4.0) https://creativecommons.org/licenses/by/4.0/
Related URLs:	Google Scholar: Sussmilch, FC UTAS Profile: Sussmilch, FC Google Scholar: Brodribb, TJ UTAS Profile: Brodribb, TJ UTAS Profile: McAdam, SAM
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