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从麦田和蔬菜地土样中筛选到2株具有较高抗菌活性的生防菌株YD4-6和NV11-4,测定了其抑菌活性和诱导水稻防御性相关酶活性的变化。抑菌活性测定结果表明YD4-6和NV11-4对水稻纹枯病菌、水稻稻瘟病菌、油菜菌核病菌和白菜黑斑病菌均具有较强的抑菌活性。两菌株均不产生几丁质酶活性,但NV11-4能产生纤维素酶活性。针对其对水稻病原菌的抑菌活性和纤维素酶活性的差异及其特性,研究了2个菌株诱导水稻防御性酶活性的变化。结果表明,YD4-6和NV11-4菌株均可有效诱导水稻PPO、POD、PAL、SOD活性增强,MDA含量升高。接种水稻纹枯病菌和使用YD4-6和NV11-4菌株,在使用48 h后,水稻防御酶的活性增加并达到最高,其中NV11-4菌株诱导活性比较持久;YD4-6使用后,诱导水稻的MDA含量增幅较大。结果显示,2个菌株均可有效的诱导水稻防御性酶活性增强和MDA含量增加。经16S rRNA鉴定后,菌株Y4-6确定为蜡质芽孢杆菌,NV11-4确定为枯草芽孢杆菌。
Two biocontrol strains YD4-6 and NV11-4 with high antibacterial activities were screened from soil samples of wheat field and vegetable field. Their antibacterial activity and enzyme activities related to defensive rice defense were determined. The results of antibacterial activity test showed that YD4-6 and NV11-4 had strong antibacterial activity against R. solanacearum, M. grisea, B. rapa and S. auricula. Both strains did not produce chitinase activity, but NV11-4 produced cellulase activity. According to their differences in antibacterial activity and cellulase activity of rice pathogens and their characteristics, the changes of defensive enzyme activities induced by two strains were studied. The results showed that both YD4-6 and NV11-4 strains could effectively induce the increase of PPO, POD, PAL and SOD activities and the increase of MDA content in rice. Inoculation of Rhizoctonia solani and the use of YD4-6 and NV11-4 strains resulted in the increase and maximum of rice defensive enzyme activity after 48 hours of use, of which strain NV11-4 showed longer lasting activity. After YD4-6 was inoculated, MDA content of rice increased significantly. The results showed that both of the two strains could effectively induce the increase of rice defensive enzyme activity and MDA content. After identified by 16S rRNA, strain Y4-6 was identified as Bacillus cereus, NV11-4 was identified as Bacillus subtilis.