Journal Article

Modulation of Reactive Oxygen Species Production During Osmotic Stress in <i>Arabidopsis thaliana</i> Cultured Cells: Involvement of the Plasma Membrane Ca<sup>2+</sup>-ATPase and H<sup>+</sup>-ATPase

Nicoletta Beffagna, Barbara Buffoli and Chiara Busi

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 46, issue 8, pages 1326-1339
Published in print August 2005 | ISSN: 0032-0781
Published online August 2005 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/pcp/pci142
Modulation of Reactive Oxygen Species Production During Osmotic Stress in Arabidopsis thaliana Cultured Cells: Involvement of the Plasma Membrane Ca2+-ATPase and H+-ATPase

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In Arabidopsis thaliana cells, hypoosmotic treatment initially stimulates Ca2+ influx and inhibits its efflux and, concurrently, promotes a large H2O2 accumulation in the external medium, representative of reactive oxygen species (ROS) production. After the first 10–15 min, Ca2+ influx rate is, however, lowered, and a large rise in Ca2+ efflux, concomitant with a rapid decline in H2O2 level, takes place. The drop of the H2O2 peak, as well as the efflux of Ca2+, are prevented by treatment with submicromolar concentrations of eosin yellow (EY), selectively inhibiting the Ca2+-ATPase of the plasma membrane (PM). Comparable changes of Ca2+ fluxes are also induced by hyperosmotic treatment. However, in this case, the H2O2 level does not rise, but declines below control levels when Ca2+ efflux is activated. Also K+ and H+ net fluxes across the PM and cytoplasmic pH (pHcyt) are very differently influenced by the two opposite stresses: strongly decreased by hypoosmotic stress and increased under hyperosmotic treatment. The H2O2 accumulation kinetics, followed as a function of the pHcyt changes imposed by modulation of the PM H+-ATPase activity or weak acid treatment, show a close correlation between pHcyt and H2O2 formed, a larger amount being produced for changes towards acidic pH values. Overall, these results confirm a relevant role for the PM Ca2+-ATPase in switching off the signal triggering ROS production, and propose a role for the PM H+-ATPase in modulating the development of the oxidative wave through the pHcyt changes following the changes of its activity induced by stress conditions.

Keywords: Arabidopsis thaliana cells; Ca2+ fluxes; Cytoplasmic pH; Osmotic stress; Plasma membrane ATPases; Reactive oxygen species; BTP, BIS–TRIS propane; [Ca2+]cyt, cytoplasmic free calcium concentration; DMO, 5,5-dimethyloxazolidine-2,4-dione; DPI, diphenylene iodonium; EY, eosin yellow; IBA, isobutyric acid; OG, oligogalacturonides; pHcyt, cytoplasmic pH; PM, plasma membrane; PPP, pentose phosphate pathway; ROS, reactive oxygen species; SAC, stretch-activated anion channels

Journal Article.  11474 words.  Illustrated.

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

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