解淀粉芽孢杆菌LJ1诱导黄瓜抗白粉病的研究

Characterization of powdery mildew resistance induced by Bacillus amyloliquefaciens LJ1 in cucumber

解淀粉芽孢杆菌LJ1是从土壤中分离得到的一株对黄瓜白粉病具有较好防效的生防细菌。田间试验发现,用LJ1发酵上清100倍稀释液喷施黄瓜幼苗,在施药后14 d时其对黄瓜白粉病的防效可达83.45%。为研究LJ1防治病害的作用机制,用LJ1发酵上清100倍稀释液喷施黄瓜幼苗,测定黄瓜叶片中的超氧化物歧化酶(SOD)、多酚氧化酶(PPO)、苯丙氨酸解氨酶(PAL)等与诱导抗病性相关的酶活性和信号分子水杨酸含量的变化,并检测了苗期根围土壤中真菌的动态。结果显示,经过LJ1发酵液处理后3种酶的活性和水杨酸的含量在不同时间点均有一个骤增的过程,其活性显著高于对照,并且7 d后土壤中的可培养真菌数量急剧减少。说明LJ1发酵液中有诱导黄瓜产生抗病性的物质,并且诱导后分泌的抗性物质对真菌具有广谱性。

Bacillus amyloliquefaciens LJ1 that was isolated from soil, possesses strongly biocontrol capacity against cucumber powdery mildew. The result of field trials showed that LJ1 is powerful in controlling cucumber powdery mildew. The 14-day control efficacy of LJ1 against powdery mildew in cucumber is 83.45%. In order to explore the biocontrol mechanism of LJ1, cucumber seedlings were sprayed with 100-fold supematant of LJ1 fermentation broth and then the activity trend of superoxide dismutase（ SOD）, polyphenol oxidase （ PPO ）, phenylalanine ammonia lyase （ PAL ） and salicylic acid （SA） in cucumber leaves were determined. Meanwhile, the quantity of fungi in cucumber rhizosphere was also detected. The results showed that all resistance index have a jump process at certain time point and the activity increased significantly comparing with that of the control group after being treated with supernatant of LJ1 ;Moreover, the quantity of fungi that could be cultured from the soil were drastically reduced and after 7d treatment. The results of present study suggested that some components in the supernatant of LJ1 fermentation broth could induce systemic resistance in cucumber seedlings and the induction-secreted active substances in cucumber rhizosphere is broad spectrum against fungi.