Abstract

Common bacterial blight (CBB) disease of the common bean (Phaseolus vulgaris) caused by Xanthomonas campestris pv. phaseoli and X. campestris pv. phaseoli var. fuscans, is one of the most damaging foliar diseases of common bean production in Ethiopia. CBB causes economic losses due to reduction in seed quality and yield in common bean producing regions of Ethiopia. Currently, information on the genetic diversity of CBB strains in Ethiopia has been lacking. Here, for this specific study common bean bacterial blight strains were obtained from infected leaves collected from diverse bean growing areas. The collected strains of CBB were characterized to study the genetic diversity and relatedness of the CBB strains using repetitive extragenic elements polymerase chain reaction (rep-PCR) genomic fingerprinting technique. Analysis of Molecular Variance (AMOVA) revealed the existence of genetic diversity among bacterial strains and confirmed the presence of genetically distinct strains in Ethiopia. CBB pathogens are seed-borne so the lack of geographic differentiation among the six-different common bean growing localities could be the result of the distribution of one or some limited bacterial genotypes. Common bean improvement programs that develop CBB-resistant bean varieties for higher production should consider this information to determine the relevance and extent of resistance of improved bean cultivars.

Keywords: Rep-PCR fingerprinting; Genetic diversity; Common bacterial blight, Disease resistance