Genomic regions associated with chocolate spot (Botrytis fabaeSard.) resistance in faba bean (Vicia fabaL.)

Chocolate spot (CS), caused by Botrytis fabae Sard., is an important threat to global faba bean production. Growing resistant faba bean cultivars is, therefore, paramount to preventing yield loss. To date, there have been no reported quantitative trait loci (QTLs) associated with CS resistance in faba bean. The objective of this study was to identify genomic regions associated with CS resistance using a recombinant inbred line (RIL) population derived from resistant accession ILB 938. A total of 165 RILs from the cross Mélodie/2 × ILB 938/2 were genotyped and evaluated for CS reactions under replicated controlled climate conditions. QTL analysis identified five loci contributing to CS resistance on faba bean chromosomes 1 and 6, accounting for 5.0–23.4% of the total phenotypic variance. The sequences of SNP markers linked to resistance QTLs on chromosome 1 that have the largest effects encode multiple classes of putative disease and/or defense-related genes. The results of this study not only provide insight into disease-resistance QTLs, but also can be used as potential targets for marker-assisted breeding in faba bean genetic improvement for CS resistance. Key message QTL mapping identified key genomic regions associated with chocolate spot resistance on faba bean chromosomes 1 and 6, which may serve as novel genetic tools to develop disease-resistant faba bean cultivars.