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Changes in Stomatal Behavior and Guard Cell Cytosolic Free Calcium in Response to Oxidative Stress.

McAinsh, M. R. and Clayton, H. and Mansfield, T. A. and Hetherington, A. M. (1996) Changes in Stomatal Behavior and Guard Cell Cytosolic Free Calcium in Response to Oxidative Stress. Plant Physiology, 111 (4). pp. 1031-1042. ISSN 1532-2548

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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 viologan 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.

Item Type: Article
Journal or Publication Title: Plant Physiology
Subjects: G Geography. Anthropology. Recreation > GE Environmental Sciences
Departments: Faculty of Science and Technology > Lancaster Environment Centre
Faculty of Science and Technology > Engineering
ID Code: 22130
Deposited By: ep_ss_importer
Deposited On: 17 Feb 2009 11:25
Refereed?: No
Published?: Published
Last Modified: 26 Jul 2012 15:56
Identification Number:
URI: http://eprints.lancs.ac.uk/id/eprint/22130

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