Diversidade genotípica e virulência de Xanthomonas spp. patogênicas ao feijoeiro

Abstract

The common bean (Phaseolus vulgaris L.) is cultivated in several regions of Brazil under different edaphoclimatic conditions. Diseases are the main causes of reduced productivity of this crop. Xanthomonas phaseoli pv. phaseoli (Xpp) and X. citri pv. fuscans (Xcf) are the etiological agents of common bacterial blight (CBC), the main bacteriosis that affects this crop. Among the strategies of integrated disease management, genetic resistance stands out, in the search for resistant materials it is necessary to know the genetic diversity of these pathogens. In this perspective, the present work had as objectives: to obtain isolated of Xanthomonas spp. from plants with symptoms of CBC from bean; identify the isolates using specific primers; characterize the isolates for pigment production; evaluate the genetic diversity of Xanthomonas spp. by rep-PCR and to evaluate the virulence of Xanthomonas spp. to the bean plant. Twelve Xpp isolates and two bean cultivars, Rudá and BRS Esplendor, susceptible and resistant respectively, were used. Primers X4c and X4e were sufficient to identify Xpp species. Nine isolates produced brown pigmentation in the evaluated medium and the other three did not produce pigment. There are at least three genetic lines within X. phaseoli pv. phaseoli. There was a difference in the virulence of the isolates, with M 354 being the most virulent isolate. These results evidence the existence of virulence variability in the studied isolates.