Alterations in the Activities of Active Oxygen Scavenging Enzymes of Wheat Leaves Subjected to Water Stress : ENVIRONMENTAL AND STRESS RESPONSES : PROTEINS, ENZYMES AND METABOLISM

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The effects of water stress on the alterations in the activities of active oxygen scavenging enzymes of primary wheat leaves were studied by incubating the leaf segments with different concentrations of polyethylene glycol solutions. Water stress caused a faster decline in the chlorophyll and protein contents and an increase in the level of proline relative to the controls. Catalase activity initially increased with time and then declined in the control leaf segments and imposition of water stress prevented the increase to different degrees depending upon the degree of stress. Water stress also caused a rapid increase in the activity of superoxide dismutase (SOD). Ascorbate peroxidase (APOX) activitiy increased in the leaves subjected to mild water~stress but declined during severe water stress while glutathione reductase (GR) activity increased under all water stress conditions studied here as compared to the control. Lipid peroxidation was enhanced under severe water stress conditions but not under mild water stress. The changes in the different parameters followed in this study, thus, are dependent upon the degree of water stress. The increases in the activities of SOD and GR in response to water stress are probably due to the de novo synthesis of enzymatic proteins. Decline in the efficacy of the H_2O_2 decomposing system is probably responsible for the oxidative damage occurring in water stressed leaves.
日本植物生理学会の論文