Caracteriza？？o de popula？？es de Ralstonia solanacearum Smith em tabaco (Nicotiana tabacum L.) no Brasil

ralstonia solanacearum, causal agent of bacterial wilt on different hosts, including members of solanaceae, causes severe losses in tobacco crop, if not managed. it is a complex species and classified in several ways. lately, the species was divided into three taxonomic levels: phylotype, sequevar and clone. due to the lack of studies on populations of r. solanacearum in tobacco, this research aimed to characterize 120 isolates from soil and wilted tobacco plants, from 13 counties from paraná, 24 from santa catarina, 13 from rio grande do sul, one from paraíba and two from pernambuco, by biovar, phylotype, and by using repetitive polymerase chain reaction (rep-pcr) element (box, eric and rep) primers. the results indicated that all isolates belong to the biovar 1 and phylotype ii. although there was homogeneity regarding biovar and phylotype, the results of rep-pcr allowed the formation of six groups (a, b, c, d, e and f) from 61% of similarity, regardless of sample type, geographical origin, collecting date or cultivar. groups a and b were those that had the greatest number of isolates, 47 and 20 clonal lines, respectively. knowledge regarding r. solanacearum population variability as well as the virulence of different isolates may help in the success of breeding programs and integrated disease management.