Abstract: In order to clarify new fungal activator protein induced resistance in rice and its physiological mechanism, changes of peroxidase (POD), polyphenol oxidase (POD), superoxide dismutase (SOD) and catalase (CAT) activities and hydrogen peroxide (H₂O₂) content in rice seedlings were determined at various time points after activator protein treatment. The results showed that activator protein could induce resistance in rice against blast fungus and bacterial blight. The resistance induced by activate protein at the concentration of 1-6 μg·mL^-1 against blast fungus and bacterial blight was 45.2%-71.4% and 47.6%-66.3%, respectively, and the best results were achieved at the concentration of 6 μg·mL^-1 activate protein. Compared with control group, the activities of POD, PPO and SOD and hydrogen peroxide content in rice seedlings were increased with different levels, but CAT activities inhibited 3-15 d after the rice seedlings treated with the concentration of 2 μg·mL^-1 activator protein. These findings showed that activator protein-induced resistance in rice was closely related to active oxygen metabolism.

Key words: activator protein, rice disease, induced resistance, active oxygen metabolism