贝莱斯芽孢杆菌Bv-303对水稻白叶枯病菌的拮抗活性及其应用

Antagonistic activity and application of Bacillus velezensis strain Bv-303 against rice bacterial-blight disease caused by Xanthomonas oryzae pv. oryzae

摘要:

本研究明确了一株新型贝莱斯芽孢杆菌（Bacillus velezensis） Bv-303菌株对黄单胞杆菌水稻致病变种（Xanthomonas oryzae pv. oryzae，Xoo）的拮抗活性及其对水稻白叶枯病（bacterial-blight，BB）的生物防治效果。采用牛津杯法测定了菌株Bv-303发酵上清液（cell-free supernatant，CFS）对白叶枯病菌体外拮抗的活性及其稳定性；通过对接种白叶枯病菌的水稻叶片进行喷雾处理，在水稻体内测试了该菌株发酵液（cell-culture broth，CCB）、发酵上清液及菌悬液（cell-suspension water，CSW）对白叶枯病菌的抑制效果；并统计了该菌株对水稻种子发芽率与幼苗生长的影响。结果表明，在体外，菌株Bv-303发酵上清液对白叶枯病菌的生长抑制率可达85.7%–88.0%，对热、酸、碱、紫外线等具有较好的稳定性；在水稻叶片上，喷施该菌株的发酵液、发酵上清液及菌悬液均能提高植株对白叶枯病的抗性，其中发酵液的效果最佳，抗病性提高率高达62.7%；且发酵液对水稻种子萌发和幼苗生长均没有副作用。因此，菌株Bv-303对水稻白叶枯病害的生物防治具有较好的应用潜力。

Abstract:

In this study, a new Bacillus velezensis strain Bv-303 was identified and its biocontrol effect against rice bacterial-blight (BB) disease caused by Xanthomonas oryzae pv. oryzae (Xoo) was investigated. Cell-free supernatant (CFS) of strain Bv-303 under different growth conditions were prepared to test the antagonistic activity and stability against Xoo by the Oxford-cup method in vitro. The antibacterial effect of strain Bv-303 to BB disease in rice were further analyzed in vivo by spraying the cell-culture broth (CCB), CFS and cell-suspension water (CSW), respectively, on the rice leaves inoculated with Xoo. Additionally, rice seeds germination rate and seedling growth under the strain Bv-303 CCB treatment were tested. The results showed that the strain Bv-303 CFS significantly inhibited Xoo growth by 85.7%‒88.0% in vitro, which was also stable under extreme environment conditions such as heat, acid, alkali and ultraviolet light. As tested in vivo, spraying the CCB, CFS or CSW of strain Bv-303 on the Xoo-infected leaves enhanced rice plant resistance to BB disease, with CCB showing the highest increase (62.7%) in disease-resistance. Notably, CCB does not have negative effects on rice seed germination and seedling growth. Therefore, strain Bv-303 has great potential for biocontrol of the rice BB disease.