Pathogenicity structure of the Xanthomonas oryzae pv. oryzae population causing rice bacterial blight in Vietnam

Abstract The rice bacterial blight caused by Xanthomonas oryzae pv. oryzae (Xoo) bacteria is rice’s most destructive disease. Due to the potential biomagnification caused by bactericides, deploying host resistance is the most effective method to protect the rice harvest. Studying the pathogenicity structure of the Xoo population helps propose the best breeding strategies to use the resistance gene pool. Among 12 resistance genes validated, xa5 and Xa21 maintained their efficacy against the Xoo population in Vietnam. Other genes, including Xa7 and xa13, remained effective in certain regions. The most destructive Xoo races distribute in the South, where intensive rice production was practiced. The same Xoo races found in different ecological regions illustrated the pathogen migration between adjacent areas. This manuscript proposed a designation system that converts the response of the differential set to each Xoo isolate into a binary, then into an octal system to name Xoo races appropriately.