Genetic diversity of Ralstonia solanacearum isolated from tobacco in Baise, Guangxi

ObjectiveGenetic diversity analysis for Ralstonia solanacearum isolated from tobacco in Baise, Guangxi was studied in order to explore occurrence and epidemic regulation in Baise tobacco planting region and pathogenic mecha-nism of R. solanacearum. MethodSixty-nine representative strains of R. solanacearum isolated from different places in Baise tobacco planting area of Guangxi were analyzed for genetic diversity by pathogenicity and biovar determination , and Box-PCR analysis. ResultAll the tested strains presented obvious pathogenicity differentiation. The proportions belong-ing to high , moderate and low pathogenicity were 17.39%, 62.32% and 20.29% respectively. Strains with moderate pathogenicity were dominant ones. Base on biovar test, the biovar of the tested strains were complex. Thirty-seven strains belonged to biotypeⅢor subtype biochemicalⅢ-1,Ⅲ-3 andⅢ-4;twenty-three were biotypeⅠ;one belonged to bio-type Ⅱ and eight belong to atypical biovar. BOX-PCR analysis indicated that there was rich genomic diversity among all the tested R. solanacearum strains. According to clustering analysis, genetic diversity was related to geographical origin, pathogenicity and biovar to some extents. But there were no strain clusters with the same geographical origin , pathogenicity and biovar. ConclusionR. solanacearum isolated from Baise, Guangxi has rich genetic diversity and complex biovar, and it may be one of the reasons why bacterial wilt causes more severe damages year by year in Baise tobacco planting area.