Ralstonia solanacearum

Ralstonia solanacearum is an aerobic non-sporing, Gram-negative plant pathogenic bacterium. R. solanacearum is soil-borne and motile with a polar flagellar tuft. It colonises the xylem, causing bacterial wilt in a very wide range of potential host plants. It is known as Granville wilt when it occurs in tobacco. Bacterial wilts of tomato, pepper, eggplant and Irish potato caused by Ralstonia solanacearum were among the first diseases that Erwin Frink Smith proved to be caused by a bacterial pathogen. Because of its devastating lethality, R. solanacearum is now of the more intensively studied phytopathogenic bacteria and bacterial wilt of tomato is a model system for investigating mechanisms of pathogenesis. Ralstonia was recently classified as Pseudomonas with similarity in most aspects, except that it does not produce fluorescent pigment like Pseudomonas. The genome of R. solanacearum Strain GMI1000 has been sequenced. Within the R. solanacearum species complex, there are four major monophyletic clusters of strains, termed phylotypes, that are geographically distinct: phylotypes I-IV are found in Asia, America, Africa, and Oceania, respectively.