Enhancement of senescence in excised rice leaves by hydrogen peroxide

Abstract

Changes in the catalase activity and the effect of hydrogen peroxide (H 2 O 2 ) were studied during the senescence of excised rice (Oryza sativa L. cv. Ratna) leaves. Catalase activity declined upon detachment of leaves. Regression analysis showed a strong positive correlation between the decline in the catalase activity with the decline in the soluble protein content (r = 0.9827; n = 13). Infiltration of H 2 O 2 into the leaves accelerated chlorophyll loss and α-amino nitrogen accumulation. Infiltration of glycolate or xanthine (serving as substrates for the formation of H 2 O 2 ) into the leaves had a similar effect. Application of aminotriazole, a strong inhibitor of catalase, also accelerated the senescence of excised rice leaves. These results indicate that leaf senescence can be accelerated by increasing the endogenous H 2 O 2 level in the leaf tissues.