Genome-wide association study on soybean canopy wilting under drought stress conditions in a rainout-shelter greenhouse

Drought is one of the most important abiotic stresses affecting plant growth and productivity worldwide. Soybean [ Glycine max (L.) Merr.] is particularly sensitive to drought stress, which can cause yield losses of up to 40%. This study aimed to identify genomic regions associated with canopy wilting, a key indicator of drought response in soybean, using genome-wide association analysis. A total of 286 soybean accessions obtained from the National Agrobiodiversity Center, Republic of Korea, were evaluated for canopy wilting under drought conditions in a rainout-shelter greenhouse over three consecutive years. The accessions were genotyped using the Axiom ® 180K SoyaSNP array, and a total of 68,375 high-quality single-nucleotide polymorphisms (SNPs) were used for genome-wide association analysis with the Bayesian-information and Linkage-disequilibrium Iteratively Nested Keyway (BLINK) model. Six significant SNPs were identified on chromosomes 5, 9, 12, 13, and 14, suggesting a polygenic genetic architecture of canopy wilting. All significant SNPs were located within ±1 Mb of genomic regions previously reported to be associated with canopy wilting-related traits in soybean. Linkage disequilibrium (LD) analysis identified an LD block encompassing the significant SNPs, within which 36 candidate genes were detected. Several of these genes were related to receptor-like kinases, RNA-processing proteins, and stress-responsive metabolic pathways, suggesting that multiple regulatory mechanisms contribute to canopy wilting responses in soybean. These findings enhance our understanding of the genetic architecture underlying drought tolerance in soybean and provide valuable genetic resources to facilitate marker-assisted selection for the development of drought-tolerant cultivars.