Genome-wide Association Analysis for Drought Tolerance and Associated Traits in Common Bean

A genome-wide association study explored the genetic basis of variation for drought tolerance and related traits in a Middle American diversity panel comprising 96 common bean (Phaseolus vulgaris L.) genotypes. The panel was grown under irrigated and rainfed conditions and single nucleotide polymorphism (SNP) data were used to explore the genetic diversity and ancestry of the panel. Varying levels of admixtures and distinctly divergent individuals were observed. Estimations of genome-wide heterozygosity revealed that, on average, greater diversity is present in individuals with Mesoamerica (3.8%) ancestry, followed by admixed individuals (2.3%). The race Durango had the lowest level of heterozygosity (1.4%). We report 27 significant marker-trait associations based on best linear unbiased predictors. These associations include seven markers for shoot biomass at harvest under irrigation and five markers under rainfed conditions on P. vulgaris (Pv) chromosome Pv11, two markers for shoot biomass at flowering under irrigation on Pv02 and Pv08, two markers for seed size under irrigated and rainfed conditions on Pv09, seven markers for lodging score under irrigation on Pv02 and Pv07, one marker for leaf elongation rate on Pv03 and one for wilting score on Pv11. Positional candidate genes, including Phvul. 011G102700 on Pv11, associated with wilting, were identified. The SNP ss715639327 marker was located in the exon region of the PvSIP1;3 gene, which codes for an aquaporin associated with water movement in beans. Significant quantitative trait loci identified in this study could be used in marker-assisted breeding to accelerate genetic improvement of drought tolerance in common bean.