Stomatal behavior in oxidative stress

 

Changes in stomatal behavior and guard cell cytosolic free calcium in response to oxidative stress.

by McAinsh M. R., Clayton H., Mansfield T. A., Hetherington A. M. (1996)

martin_mcainsh
Martin R Mcainsh, Lancaster University

Clayton H.

Mansfield T. A.

AS-272722915754002@1442033618447_l
Alistair M. Hetherington, School of Biological Sciences, University of Bristol, UK

in Plant Physiology 111: 10311042.  – 

PubMedCASWeb of Science – PubMed Abstract | Google Scholar – 

https://www.ncbi.nlm.nih.gov/pubmed?Db=pubmed&Cmd=ShowDetailView&TermToSearch=12226345

Abstract

We have investigated the cellular basis for the effects of oxidative stress on stomatal behavior using stomatal bioassay and ratio photometric techniques.

Two oxidative treatments were employed in this study: (a) methyl viologen, which generates superoxide radicals, and (b) H2O2. Both methyl viologen and H2O2 inhibited stomatal opening and promoted stomatal closure. At concentrations [less than or equal to]10-5 M, the effects of methyl viologen and H2O2 on stomatal behavior were reversible and were abolished by 2 mM EGTA or 10 [mu]M verapamil. In addition, at 10-5 M, i.e. the maximum concentration at which the effects of the treatments were prevented by EGTA or verapamil, methyl viologen and H2O2 caused an increase in guard cell cytosolic free Ca2+ ([Ca2+]i), which was abolished in the presence of EGTA.

Therefore, at low concentrations of methyl viologen and H2O2, removal of extracellular Ca2+ prevented both the oxidative stress-induced changes in stomatal aperture and the associated increases in [Ca2+]i. This suggests that in this concentration range the effects of the treatments are Ca2+-dependent and are mediated by changes in [Ca2+]i.

In contrast, at concentrations of methyl viologen and H2O2 > 10-5 M, EGTA and verapamil had no effect. However, in this concentration range the effects of the treatments were irreversible and correlated with a marked reduction in membrane integrity and guard cell viability. This suggests that at high concentrations the effects of methyl viologen and H2O2 may be due to changes in membrane integrity.

The implications of oxidative stress-induced increases in [Ca2+]i and the possible disruption of guard-cell Ca2+ homeostasis are discussed in relation to the processes of Ca2+-based signal transduction in stomatal guard cells and the control of stomatal aperture.

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Published by

Willem Van Cotthem

Honorary Professor of Botany, University of Ghent (Belgium). Scientific Consultant for Desertification and Sustainable Development.

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