Genome-Wide Association Mapping of Canopy Wilting in Diverse Soybean Genotypes.

Drought stress is a major global constraint for crop production. Slow canopy wilting is a promising trait associated with transpiration for improving drought tolerance. This study’s objective was to identify SNP markers associated with canopy wilting. A population consisting of 373 MG IV soybean genotypes was grown in multiple environments to evaluate canopy wilting. Statistical analysis of phenotype indicated wide variation of the trait, with significant effects of genotype (G), environment (E) and G x E interaction. Over 42,000 SNP markers were obtained from the Illumina Infinium SoySNP50K iSelect SNP Beadchip. After quality control, 31,260 SNPs were used for association analysis. To control the false positives due to population stratification, FarmCPU model was used for association analysis, which not only reduce the false positives and but also reduce the false negatives. Several environment-specific and 9 common SNPs (present in more than one environment) were identified using the FarmCPU model. Most of these identified SNPs were located closely to previously reported QTLs for wilting. Several genes were identified using the significant SNPs that may have direct association with transpiration. Favorable alleles from significant SNPs may be an important resource for pyramiding genes to improve drought tolerance and for identifying the parental genotypes for a breeding program.