Transfer of common blight (Xanthomonas campestris pv phaseoli) resistance from Phaseolus coccineus Lam. to P. vulgaris L. through interspecific hybridization

Four interspecific backcross populations derived from hybridizations between Phaseolus vulgaris × (P. vulgaris × P. coccineus) were produced to transfer common blight (Xanthomonas campestris pv phaseoli) resistance from a blight–resistant accession of P. coccineus to P. vulgaris white bean cultivars and to determine the association between blight resistance and some agronomic characteristics. Frequency distribution of leaf blight resistance ratings in the BCF 2 and BCF 3 generations and of percent pod blight infection in the BCF 3 generation appeared to be continuous, ranging between the respective parental resistance reactions. This indicated that the transfer of common blight resistance from P. coccineus to P. vulgaris was feasible. Scores for leaf and pod blight were not associated indicating differential blight resistance reactions of the two plant organs. Leaf blight was negatively correlated with days to blossom but was not correlated with growth habit and pod set except for one cross in which leaf blight and pod set were associated. Percent pod blight was negatively correlated with days to blossom in two crosses. Pod blight was not associated with growth habit and pod set except for one cross in which it was associated with pod set. Days to blossom and pod set were associated. Implications of these findings in the breeding of blight resistant white bean cultivars are discussed.Key words: Interspecific crosses, Phaseolus coccineus, Phaseolus vulgaris, Xanthomonas campestris pv phaseoli, common blight, correlation