Multi-Environment QTL Mapping of Rust Resistance in Faba Bean (Vicia faba L.) to Uromyces viciae-fabae

Faba bean rust is one of the major threats to the cultivation of faba beans worldwide. Three genes for rust resistance (Uvf-1, Uvf-2 and Uvf-3) and fifteen marker-trait associations have been identified so far. This study examines the genetic basis of rust resistance derived from BPL-261, an accessions that exhibits low infection frequency and a long latency period. We constructed a genetic map based on a RIL6 population derived from the BPL-261/Vf-274 cross, which consists of 91 individuals. Subsequent generations were used to evaluate rust resistance in Lattakia (Syria), Kafr El-Sheikh (Egypt) and Córdoba (Spain). A total of six QTLs for resistance were detected on chromosomes II, III, IV and V. Comparative analyses suggest that the QTL located on chromosome V is likely to be associated with Uvf-3. The QTL on chromosome III is close to Uvf-2 but it seems to be a different QTL since the confidence intervals do not overlap. Finally, the other QTLs constitute additional sources of rust resistance in faba beans. Functional analysis of the candidate genes within the confidence intervals suggests the hypothetical involvement of various resistance mechanisms, with salicylic acid playing a significant role but it should be confirmed with further studies. Our results advance understanding of rust resistance in faba bean. Markers identified in this study should be used to develop kompetitive allele-specific PCR (KASP) assays, after their utility has been confirmed in different genetic backgrounds. This will contribute to the development of durable rust-resistant faba bean cultivars.