Complete Genome Sequences Of Ralstonia Solanacearum Phylotype Ⅰ Strain OE1-1 And Its Comparison With Other Strains Of Ralstonia Solanacearum Species Complex

Ralstonia solanacearum is a major phytopathogen that attacks many crops and other plants over a broad geographical range.The extensive genetic diversity of strains responsible for the various bacterial wilt diseases has in recent years led to the concept of an R.solanacearum species complex(RSSC),which is classified into five phylotypes:ph I,ph IIA,ph IIB,ph Ⅲ,and ph IV.Here,we presented the complete genome sequence of OE1-1 and performed genomic comparison with the other 68 RSSC strains,genome sequences of which have been available to date.The fact that phylotypes of the RSSC can be confirmed by their GC contents and general genomic similarity to one another,but either geographic origins or genome sizes,was underlined.With phylogenetic analysis,all these strains can be clustered into five groups that match with phylotypes,and a Korean strain KACC10722 is suggested to be ph IV based on its GC content,phylogenetic analysis and genomic similarity to others.In addition to offering new insights into the RSSC’s genomic history,the pan-genome and comparative genomic analyses offer helpful hints for identifying and characterizing the genetic components that contribute to bacterial virulence and host specificity.Although OE1-1 and EP1 exhibit the highest genomic similarity of 99.87%among the RSSC,OE1-1 is virulent in tobacco plants,but EP1 and GMI1000 cause hypersensitive response(HR)in tobacco leaves.Some type Ⅲ effectors(T3Es)are validated to be responsible for the hypersensitive response(HR)even though the type Ⅲ effectors(T3Es)are extremely abundant and greatly variable among the RSSC.We performed an inventory comparison on all T3 Es among OE1-1,EP1,and GMI1000.Eight T3 Es are identified to be differently present in three stains,including Rip AA,Rip AL,Rip C2,Rip F2,Rip P1,Rip T,Rip S7,and Rip U.We focused on 3 typical T3Es: Rip AA,Rip P1,and Rip T,while they are not virulence determinants of OE1-1 in tobacco plants.Further experiments are performing to elucidate the genetic basis of diversified virulence and host range in OE1-1,EP1 and GMI1000.