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Partial inhibition of ABA-induced stomatal closure by calcium-channel blockers.

McAinsh, Martin R. and Brownlee, C. and Hetherington, Alistair M. (1991) Partial inhibition of ABA-induced stomatal closure by calcium-channel blockers. Proceedings of the Royal Society B: Biological Sciences, 243 (1308). pp. 195-201. ISSN 0962-8452

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Abstract

ABA-induced increases in [Ca2+]cyt (cytosolic free Ca2+) may result from Ca2+ influx from the apoplast and/or release from intracellular stores. In this paper, Ca2+-channel blockers have been used to investigate this question in the detached epidermis of Commelina communis. Examples from the benzothiazepine, dihydropyridine and phenylalkylamine series all inhibited ABA-induced stomatal closure: (+/-) verapamil > nifedipine > diltiazem. Inhibition was partial, the magnitude of the effect being dependent on both the concentration of ABA and that of the channel blocker. The maximum inhibition observed in the presence of 100 nM ABA was approximately 66% at high (100 nM) concentrations of (+/-) verapamil or nifedipine. In the near absence of extracellular Ca2+ (2 mM EGTA) ABA-induced stomatal closure was reduced by approximately 22% and the inhibition by Ca2+-channel blockers abolished. Inhibition by (+/-) verapamil was totally reversible and exhibited signs of stereospecificity, the s(-) enantiomer being a more potent inhibitor of ABA-induced stomatal closure than the R(+) enantiomer. Bay K 8644 (a fluorinated analogue of nifedipine) exhibited biphasic action on 500 uM Ca2+-induced stomatal closure, i.e. agonistic at low concentrations (10 nM), antagonistic at high concentrations (> 10 nM to 100 uM), but did not affect ABA-induced stomatal closure. These results suggest that Ca2+ release from intracellular stores may be important in the ABA-induced increase in [Ca2+]cyt associated with stomatal closure. They do not, however, exclude a contribution of Ca2+ influx from the apoplast.

Item Type: Article
Journal or Publication Title: Proceedings of the Royal Society B: Biological Sciences
Uncontrolled Keywords: Ca2+ ; cytosolic calcium ; stomata ; guard cells ; channel blocker ; ABA ; abscisic acid
Subjects: Q Science > QH Natural history > QH301 Biology
Departments: Faculty of Science and Technology > Lancaster Environment Centre
Faculty of Science and Technology > Engineering
ID Code: 26857
Deposited By: Dr Martin R McAinsh
Deposited On: 31 Jul 2009 11:01
Refereed?: Yes
Published?: Published
Last Modified: 31 Oct 2014 14:21
Identification Number:
URI: http://eprints.lancs.ac.uk/id/eprint/26857

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