Selection and Characterization of Antagonistic Bacteria as a High Potential Control Agent for Xanthomonas oryzae pv. oryzae Causing Bacterial Leaf Blight Disease in Purple Rice

Abstract

Bacterial leaf blight disease is one of the most serious diseases in rice caused by Xanthomonas oryzae pv. oryzae. Purple rice is one of the rice varieties that has been infected by this pathogen. Thus, screening and selecting highly efficient antagonistic bacteria for controlling the pathogen is necessary for disease control to reduce epidemics and crop loss. Forty-eight isolates of antagonistic bacteria were isolated from rice rhizosphere soil. The highly effective antagonistic bacteria were selected by dual culture method. The results showed bacteria strains KY16 and KY17 were the most effective antagonists that were able to inhibit X. oryzae pv. oryzae. The inhibition growth zone of antagonists were approximately 12.70 mm and 11.95 mm, respectively. The morphological and some biochemical characteristics of antagonistic bacteria belong to Bacillus sp. Additionally, the antagonists KY16 and KY17 were identified as Bacillus siamensis based on 16S rRNA, gyrA, and rpoB gene sequences. Antimicrobial biosynthesis genes of the antagonistic bacteria were also examined. The results revealed that iturin A and surfactin biosynthesis genes were detectable. From this study, the selected antagonistic bacteria can be used to control the bacterial leaf blight disease of purple rice in rice paddy fields.