Sources of Resistance to Common Bacterial Blight, Halo Blight and Bacterial Wilt in Phaseolus vulgaris L. Elite Lines

Abstract

Field inoculation tests were performed in 2009-2013 with 32 snap bean lines (Phaseolus vulgaris L.) from six crosses for their leaf and pod reaction towards two isolates of Xanthomonas axanopodis pv. phaseoli [Xap] – the causal agent of common bacterial blight, and two races of Pseudomonas savastanoi pv. phaseolicola [Psp] - the causal agent of halo blight. The disease response of the lines to an isolate of Curtobacterium flaccumfaciens pv. flaccumfaciens [Cff] – the causal agent of bacterial wilt was also studied. A differential reaction of lines to Psp races was observed for each of the reactions on leaves and pods. Responses of the lines to bacterial wilt differed by each of the symptoms – necrotic lesions, stunting and wilting. A positive correlation (r= 0.89) between the genotype disease reaction and the virulence of the Xap isolates included in the study was obtained. Among the studied genotypes, three lines of hybrid combination #952 demonstrated high_ to moderate_ resistance on both leaves and pods to Psp and Xap. They possessed green flat snap pods, determinated growth habit Ia and good agricultural characteristics. Three lines resulting from crosses #1074 and #1056 were highly to moderately resistant to halo blight and bacterial wilt. Above outlined genotypes were suitable sources of resistance to bean bacterioses in Bulgaria and their incorporation in the snap bean breeding program would allow selecting of cultivars with resistance to a considerable part of the pathogens’ populations