[Antagonistic activity and application of strain Bv-303 against rice bacterial-blight disease caused by pv. ].

In this study, a new strain Bv-303 was identified and its biocontrol effect against rice bacterial-blight (BB) disease caused by pv. () was investigated. Cell-free supernatant (CFS) of strain Bv-303 under different growth conditions were prepared to test the antagonistic activity and stability against by the Oxford-cup method . The antibacterial effect of strain Bv-303 to BB disease in rice were further analyzed by spraying the cell-culture broth (CCB), CFS and cell-suspension water (CSW), respectively, on the rice leaves inoculated with . 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 growth by 85.7%‒88.0% , which was also stable under extreme environment conditions such as heat, acid, alkali and ultraviolet light. As tested , spraying the CCB, CFS or CSW of strain Bv-303 on the -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.