枯草芽孢杆菌TR21对香蕉抗病相关酶活的诱导作用

为筛选能显著诱导香蕉抗病相关酶活变化的枯草芽孢杆菌TR21（Bacillus subtilis）发酵液组分，并探讨其诱导香蕉抗病性机理，选择多酚氧化酶（PPO）、过氧化物酶（POD）和苯丙氨酸解氨酶（PAL）作为植物抗病性反应指标，采用灌根接种法，研究1株在大田对香蕉枯萎病具有良好防效的枯草芽孢杆菌TR21发酵液不同组分对香蕉根系内3种酶活性的影响。结果表明，接种TR21发酵液、菌体、上清和NB培养基后，香蕉根系内PPO、POD和PAL活性均比无菌水对照高，且都出现2次高峰，PPO、POD活性峰在接种后第3天和第7天出现，PAL活性峰则在接种后1天和5天时出现。比较不同组分接种处理诱导产生的酶活性强弱发现，接种TR21发酵液、菌体的3种酶活性均明显高于接种上清和NB的处理。可以判断TR21发酵液中主要有效诱导组分为菌体。灌根法接种TR21菌体后测定香蕉叶片中3种抗病酶的活性表明，菌体处理后叶片中PPO、POD和PAL活性均显著高于接种无菌水的对照，推测诱导系统抗性可能是TR21菌株防治香蕉枯萎病的机制之一。

The Induction of Bacillus subtilis Strain TR21 on related Enzymes of disease resistance of Banana Seedling

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.