Angular Leaf Spot Resistance Loci Associated With Different Plant Growth Stages in Common Bean

Abstract

Angular leaf spot (ALS) is a disease that causes major yield losses in the common bean crop. Studies based on different isolates and populations have already been carried out to elucidate the genetic mechanisms of resistance to ALS. However, understanding of the interaction of this resistance with the reproductive stages of common bean is lacking. The aim of the present study was to identify ALS resistancelociat different plant growth stages (PGS) by association and linkage mapping approaches. An BC2F3inter-gene pool cross population (AND 277 × IAC-Milênio – AM population) profiled with 1,091 SNPs from genotyping by sequencing (GBS) was used for linkage mapping, and a carioca diversity panel (CDP) genotyped by 5,398 SNPs from BeadChip assay technology was used for association mapping. Both populations were evaluated for ALS resistance at the V2 and V3 PGSs (controlled conditions) and R8 PGS (field conditions). Different QTL (quantitative traitloci) were detected for the three PGSs and both populations, showing a different quantitative profile of the disease at different plant growth stages. For the three PGS, multiple interval mapping (MIM) identified seven significant QTL, and the Genome-wide association study (GWAS) identified fourteen associate SNPs. Severallocivalidated regions of previous studies, andPhg-1,Phg-2, Phg-4, andPhg-5, among the 5lociof greatest effects reported in the literature, were detected in the CDP. The AND 277 cultivar contained both thePhg-1and thePhg-5QTL, which is reported for the first time in the descendant cultivar CAL143 as ALS10.1UC. The novel QTL named ALS11.1AMwas located at the beginning of chromosome Pv11. Gene annotation revealed several putative resistance genes involved in the ALS response at the three PGSs, and with the markers andlociidentified, new specific molecular markers can be developed, representing a powerful tool for common bean crop improvement and for gain in ALS resistance.