Screening of Antagonistic Bacteria from Endophytes against Walnut Blight Pathogen Xanthomonas arboricola pv. juglandis

Walnut blight caused by Xanthomonas arboricola pv. juglandis (Xaj) is the most important bacterial disease in walnut production worldwide. To seek biocontrol agents against Xaj, we screened 152 endophytic bacteria isolated from 87 plants. Through dual-culture method screening, obtained four antagonistic bacteria, ATE17, BME17, CIE17, and OFE17 which were Amaranthus tricolor, Bambusa multiplex, Canna indica, Osmanthus fragrans plants respectively. The inhibition ratios of ATE18, CIE18, Xaj on plates 1.5, 1.6, 1.3, These indicated they have good potential for blight. Subsequently, identified morphology, Gram staining, Microbial Identification System (fatty acid methyl ester analysis), as well 16S rDNA gyrB sequencing. It turns out that all strains Bacillus sp. Furthermore, two BME17 can suppress multiple plant fungal pathogens plates.