Adaptabilidade comparativa de Ralstonia pseudosolanacearum e R. solanacearum em solanáceas no estado de Pernambuco

Abstract

In the state of Pernambuco, Northeastern Brazil, bacterial wilt caused by Ralstonia pseudosolanacearum (Rpsol) (phylotype I) and R. solanacearum (Rsol) (phylotype II) can hinders the solanaceae cultivation in municipalities in all the mesoregions of the state, presenting emerging prevalence of Rpsol in the production fields of some mesoregions. To elucidate the adaptive conditions of the two species, the aim of this study was to compare representative strains of Rpsol and Rsol of the population present in Pernambuco, under different physiological, biochemical, ecological and pathogenic conditions, in order to determine possible adaptive advantages of these species. The Rpsol strains used a greater variety of carbon sources and had a greater spectrum of resistance to inhibitory substances, in addition to being more competent to infect different solanaceous hosts, presenting a faster invasion and colonization process in tomato (Solanum lycopersicum L.) roots and stems than strains from Rsol. On the other hand, Rsol strains were considered more apt to adapt to a wider range of temperature, pH and salinity, in addition to showing greater ability for biofilm formation and bacteriocin production. Based on our results, we conclude that the studied population of Rpsol had greater pathogenic and biochemical adaptability while Rsol population had greater physiological and ecological adaptability, and that because of their distinctive adaptive advantages, at the moment there is no evidence that one species may decline or extinguish the population of another one in Pernambuco state.