Genetic Diversity of Zingiberaceae Plant Isolates of Ralstonia solanacearum in the Asia-Pacific Region

The genetic diversity of Ralstonia solanacearum strains isolated from Zingiberaceae plants in the Asia-Pacific region was assessed by examining their biochemical properties, discriminating the phylogeny by polymerase chain reaction (PCR), and analyzing the egl and mutS gene sequences. These data were compared with those of reference strains covering the known diversity within the R. solanacearum species complex. Fifty-two of the Zingiberaceae plant isolates belong to either biovar 3 or biovar 4. Multiplex PCR analyses indicated that these strains belong to phylotype I. Phylogenetic analyses revealed that the investigated strains could be further divided into five or more groups and three major groups, based on the egl and mutS gene sequences, respectively. These groups were closely correlated with the host species and/or geographical origin. Our findings suggest that R. solanacearum strains affecting Zingiberaceae plants have multiple origins from within the Asia-Pacific region, and may have been disseminated with seed rhizomes.