2，6-Dichloroisonicotianic acid repressed reactive oxygen species content and fruit ripening to induce disease tolerance in banana（ Musa AAA. cv. Dongguang）

The possible mechanism of INA on disease-tolerance in postharvested banana　（Musa AAA. cv. Dongguang） was investgated. Ther results showed that INA treatment effectively reduced the disease spot sizes on the peel of banana fruit when inoculated with spore suspension of Collectotrichum musae after INA treatment and cultured for 15 d. During storage，MDA content increased in both INA treatment and control；however，INA treatment markedly inhibited the MDA content，suggesting that INA retarded the fruit ripening. The content of H2O2 in INA treatment was obviously lower than that in control from the 8th d，while high activety of NADPH oxidase in INA treatment was found from the 10th d. An induced CAT activity was found in control during storage；however，high APX activity was detected in INA treatment. During the later storage，INA induced the APX gene expression，but repressed the expression of CAT and P450. The results suggested that enhancing APX activity/gene expression could reduce H2O2 level to improve banana disease tolerance during storage.