Construction of an integrated genetic linkage map and detection of quantitative trait loci for ascochyta blight resistance in faba bean (Vicia faba L.)

Ascochyta blight (AB), caused by Ascochyta fabae Speg., is an economically important disease that has been reported in most of the faba bean growing regions worldwide. Breeding for resistance is the most environmentally acceptable and economically feasible method to address the disease, for which a detailed understanding of the genetic basis of AB resistance is required. In the current study, a genetic linkage map based on single nucleotide polymorphisms was developed from Nura × Farah recombinant inbred line (RIL) population and contained 705 loci across 1021.8 cM. The marker information from Nura × Farah map was combined with previously published maps to generate an integrated map consisting of 1850 markers distributed across six linkage groups, with a cumulative length of 1439 cM at an average density of one marker per 0.80 cM. Parents and RIL progeny were screened for AB with two strains of A. fabae and quantitative trait locus analysis identified two genomic regions explaining up to 49% of the phenotypic variation. Evaluation of linked markers in a diverse set of faba bean genotypes validated their utility for marker assisted selection. The availability of high density genetic linkage map along with the linked markers for AB resistance provides opportunities for genomics-assisted breeding, map based gene isolation and comparative genetics in faba bean.