TITLE	Effect of oxidative stress caused by hydrogen peroxide on senescence of rice leaves
AUTHOR	Jaw-Neng Lin Department of Agronomy, National Taiwan University, Taipei, Taiwan, Republic of China Ching Huei Kao Department of Agronomy, National Taiwan University, Taipei, Taiwan, Republic of China
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ABSTRACT	Lipid peroxidation is considered to be an important mechanism of leaf senescence. The peroxidation of lipids can be initiated by free radicals. H2O2 itself is active oxygen species and can react with superoxide radicals to form more reactive hydroxyl radicals in the presence of trace amounts of Fe or Cu. Thus, it is of interest to investigate the relationship between lipid peroxidation and H2O2-promoted senescence in detached rice leaves. H2O2 effectively promoted senescence and increased malondialdehyde levels in detached rice leaves under both light and dark conditions. However, the promotion of senescence by the exogenous level of H2O2 is not associated with an increase in its endogenous level. Thiourea (a scavenger of hydroxyl radical) almost completely prevented H2O2-promoted senescence and the H2O2-induced decrease in superoxide dismutase and ascorbate peroxidase activities in light and darkness. It seems that promoted senescence by H2O2 in detached rice leaves is associated free radical-induced lipid peroxidation.
KEYWORD	Free radical scavengers; H2O2; Leaf senescence; Lipid peroxidation; Oryza sativa; Oxidative stress;
ARTICLE INFO	Botanical Bulletin of Academia Sinica, Volume 39 Number 3 July 1998, page 161-165, 5 pages
PUBLISHER	Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan, Republic of China