Activity of enzymatic antioxidant defense systems in submerged rice seedlings.

摘要

The influence of complete submergence on the antioxidant capacities in three Indica rice cultivars namely Kalaputia and Khadara (tolerant type) and Sarala (susceptible type) was examined under 8 days of complete submergence and subsequent re-aeration for 24 h. The activities of all the antioxidant enzymes decreased under submergence especially after four days of the treatment. The activities of catalase, ascorbate acid peroxidase, dehydroascorbate acid reductase and glutathione reductase were more in tolerant cultivars during submergence compared to the susceptible cultivar. The activities of superoxide dismutase and guaiacol peroxidase on the other hand were more or less similar during submergence between tolerant and susceptible cultivars. The activities of the enzymes increased during re-aeration with greater degrees in tolerant cultivars after 24 h of re-aeration. Tolerant cultivars maintained higher levels of hydrogen peroxide during submergence and subsequent period of re-aeration. The reduced ascorbate levels were significantly greater in tolerant cultivars especially after re-aeration. These results indicate that during re-aeration the anti-oxidant systems involving both superoxide dismutase and ascorbate regeneration pathway takes part in protecting the rice plants from injury triggered by reactive oxygen species.