Abstract:

Common bacterial blight of common bean is one of the most widespread common bean diseases inHeilongjiangProvincein recent years. In severe cases, it can lead to large-scale yield reduction of common bean and affect grain quality. In order to explore the biocontrol bacteria resources of common bacterial blight of common bean, an antagonistic strain B2 with significant inhibitory ability on common bacterial blight of common bean was isolated and screened from the rhizosphere soil of healthy common bean. Based on microscopic observation, physiological and biochemical characteristics determination combined with 16S rDNA and gyrB sequence analysis, the strain B2 was identified as Bacillus velezensis. The antibacterial ring diameter of the strain B2 against Xanthomonas axonopodis pv. phaseoli (Xap) and Xanthomonas fuscans subsp. fuscans (Xff) were19.3 mmand21.8 mm, respectively. In the pot experiment, the control efficacy of strain B2 against Xap and Xff were 55.42% and 67.77 %, respectively. The determination of defense enzyme activity and malondialdehyde content in bean leaves showed that strain B2 could significantly increase the activities of SOD, POD, CAT and PPO in bean leaves and reduce the content of malondialdehyde. Its indicating that strain B2 could induce plant defense response to resist pathogens. In conclusion, strain B2 has good development and application potential in the biological control of common bacterial blight of common bean which caused by Xap and Xff.

Key words:

 common bacterial blight of common bean, Bacillus velezensis; control efficacy