Characterization of Ralstonia Pseudosolanacearum MSG ‐1 and Its Pathogenic Interaction With Mulberry

ABSTRACT Mulberry bacterial wilt disease is devastating to the sericulture industry, and understanding its causal agent and pathogenic mechanisms is essential for effective mulberry disease control. In this study, the strain MSG‐1, which was isolated from mulberry branches with typical bacterial wilt symptoms, was identified and designated as Ralstonia pseudosolanacearum MSG‐1 according to the pathogenic, morphological, physiological, biochemical, and molecular features. Furthermore, R. pseudosolanacearum MSG‐1 was classified as race 5, biovar I, phylotype I, and sequevar 12, and was capable of infecting mulberry but infected ginger, banana, and other Solanaceae weakly or not at all. The complete R. pseudosolanacearum MSG‐1 genome is 5.8 Mbp (66.85% GC), and a total of 1991 genes of R. pseudosolanacearum MSG‐1 were found to be significantly differentially expressed during the infection of mulberry seedlings, with 1324 genes significantly up‐regulated and 667 genes significantly down‐regulated. Seven pathogenicity‐associated candidate genes were identified, and R. pseudosolanacearum MSG‐1 pathogenicity on mulberry was significantly reduced after knocking out six of these genes. This study integrates genomic insights with the pathogenicity mechanisms of R. pseudosolanacearum MSG‐1, shedding light on the breeding of resistant mulberry varieties and precision‐based wilt control in sericulture.