Quantitative Trait Loci for Yield under Multiple Stress and Drought Conditions in a Dry Bean Population

Terminal and intermittent drought limits dry bean (Phaseolus vulgaris L.) production worldwide. Tolerance to drought exists but is difficult to breed for because of inconsistent expression across environments. Our objective was to identify quantitative trait loci (QTL) conditioning yield in a recombinant inbred line (RIL) population with consistent expression across multiple drought-stress environments. We tested 140 RILs from 'Buster' pinto (susceptible)/'Roza' pink (tolerant) for yield under multiple stresses (intermittent drought, compaction, and low fertility) across 3 yr and terminal drought across four location-years. A genetic linkage map (953 cM) was generated using single nucleotide polymorphism (SNP) markers. Two major-effect QTL were detected on Pv01 and Pv02. The Pv01 QTL, defined by the closest marker SNP50809 (47.7 Mb), explained up to 37% of the phenotypic variance for seed yield under multiple stress (including intermittent drought) and was consistently expressed each year. The Pv02 QTL, nearest SNP40055 (11.8 Mb), was detected under drought stress (R-2 = 33%) in addition to multiple stress (R-2 = 17-23%). Phenological traits cosegregated with the yield QTL and affirmed the importance of phenological plasticity in adaptation to drought stress. Late maturity contributed to increased yield under multiple and nonstress and early maturity to increased yield under terminal drought. Given major and consistent effect, further investigation of the potential for the Pv01 and Pv02 QTL in breeding for multiple abiotic stress and drought tolerance in dry bean is warranted.