Prediction of gene clusters associated with host specificity of Ralstonia pseudosolanacearum race 4 based on comparative genomic analysis

Ralstonia pseudosolanacearum race 4 differs from race 1 in being pathogenic on ginger (Zingiber officinale). Here, we used a comparative genomic analysis to predict the genes associated with this specificity of race 4 on ginger. Forty-six orthologous gene groups were found to be specific to race 4, including pathogenicity-related genes encoding polygalacturonase, type III effector, and efflux pump. Additionally, most race-4-specific genes clustered on the genomic islands in megaplasmid, suggesting these genes were introduced to the ancestry strain through horizontal transfer. This study adds to our understanding of the coevolution of R. pseudosolanacearum with hosts and the mechanisms that underlie its host specificity.