Abstract:

In order to screen different fractions of Bacillus subtilis strain TR21 fermented liquor which induced related enzymes of disease resistance of banana seedling, and explore the mechanism which induced resistance. The strain TR21 can be used to control banana fusarium wilt in fields, polyphenoase (PPO), peroxidase (POD) and phenlalanine ammonia lyase (PAL) of banana Brazil (Musa spp.) seedlings were chosen as the indicators of disease resistance of banana after being inoculated with different fractions of TR21 fermented liquor by drenching root method to reveal the disease control mechanism. The results showed that: the PPO, POD and PAL activities of banana roots inoculated with TR21 fermented liquor, cells suspension, a cell-free fermented supernatant fluid and NB liquid medium were always higher than those just inoculated with sterile water control, and there were all two activity peaks. PPO or POD activity peak reached at 3 d and 7 d after inoculation, and PAL activity peak at 1 d and 5 d. There were no difference at activity levels of these three enzymes after inoculated with TR21 fermented liquor or cells suspension, but the roots inoculated with TR21 fermented liquor or cells suspension had higher activities of PPO, POD and PAL than those inoculated with a cell-free fermented supernatant fluid and NB liquid medium control. Therefore, the main bioactive fraction in the strain TR21 fermented liquor was cell. Banana seedlings were inoculated with TR21 cells suspension by drenching root method, and the related enzymes activities of disease resistance in leaves were determinated. The results showed that the leaves had higher activities of PPO, POD and PAL than those inoculated with sterile water control. It suggested that induced systemic resistance was one of antagonistic mechanism of the strain TR21 against banana fusarium wilt.