桑树中拮抗内生细菌的分离筛选及其抑菌机制

以小麦赤霉病菌为指示菌，进行桑树拮抗内生细菌的分离筛选，开展拮抗内生细菌的对峙培养和盆栽控病试验，并采用分光光度法检测SSY26拮抗菌引入小麦穗部，小麦穗组织中的多酚氧化酶(PPO) 、过氧化物酶(POD) 和苯丙氨酸解氨酶(PAL) 的酶活性。结果显示，SSY26菌株对小麦赤霉病菌具有较好的抑制作用，抑菌率达到58.65%,显微观察显示SSY26菌株可引起小麦赤霉病菌菌丝膨大、畸形，影响其正常生长；分子鉴定SSY26菌株为芽孢杆菌属微生物。小麦盆栽试验结果表明，第18 天时SSY26菌悬液对小麦赤霉病的防治效果为27.30% ,与化学药剂处理组没有显著差异，且桑树内生细菌SSY26引入到小麦穗部，可提高穗部组织中PPO、PAL及POD等防御酶活性。

Isolation, screening and antibacterial mechanism of antagonistic endophytic bacterium from Morus alba L.

The antimicrobial activity of endophytic bacterium from Morus alba L. was examined against wheat head blight using dual culture test and disease-control pot experiment, and the related enzymes activities (PPO, PAL and POD) in wheat spike treated with antagonistic endophytic bacteria SSY26 were detected by spectrophotometric method. The results showed that the SSY26 strain had strong inhibit effect against wheat head blight, with inhibitory rate of 58.65%, and the SSY26 strain, which was identified as Bacillus by molecular identification, could cause the expansion and deformity of phytopathogen mycelia of wheat head blight. The pot experimental results showed that the inhibit effect was 27.30% in the eighteenth day after treated with suspensions of SSY26 strain, without significant difference between SSY26 strain suspensions and chemical treatment, and the enzymes activities of PPO, PAL and POD in wheat spike increased treated with the suspensions of SSY26 strain.