Genetic study of the resistance of faba bean (Vicia faba) against the fungus Ascochyta fabae through a genome-wide association analysis

Ascochyta fabae is a fungal pathogen responsible for marked yield losses in spring and winter faba beans worldwide. The aim of this genome-wide association study (GWAS) using 188 diverse winter faba bean inbred lines was to exploit earlier Ascochyta blight resistance studies and to identify new resistance loci. Phenotyping after artificial inoculation under controlled conditions revealed significant variation for all eight scored disease traits. This GWAS was based on 1829 AFLP marker and 229 SNP marker, including 17 so-called ‘guide’ SNP markers. The latter were identified by map fragment alignments between the consensus smap of Webb et al., (2016, Plant Biotechnology Journal, 14, 177–185) and three earlier published Ascochyta blight resistance studies. A total of 12 markers were found significantly associated with six traits, explaining 5.6% to 21.7% of the phenotypic variance. One ‘guide’ SNP on chromosome III co-localizes with the known resistance QTL Af1 on chromosome III. Probably nine new resistance trait-associated marker loci were identified which will improve resistance breeding on winter faba beans and support a broader inclusion of the crop into rotations.