Genome-Wide Association Study Identifies QTNs and Candidate Genes Conferring Resistance to Soybean Frogeye Leaf Spot Race 7.

Soybean (Glycine max) is a major economic and food crop whose yield is severely affected by frogeye leaf spot (FLS), caused by Cercospora sojina. Current knowledge of resistance genes remains insufficient for effective molecular breeding. In this study, a recombinant inbred line (RIL) population derived from a cross between the resistant parent, Henong 60 (H60), and the susceptible parent, Dongnong L13 (DN L13), was evaluated under field conditions in Acheng (AC) and Xiangyang (XY). Plants were artificially inoculated with physiological race 7 of C. sojina, and disease severity at the R3 growth stage was recorded. Genotyping using the SoySNP660K chip yielded 54,836 high-quality single-nucleotide polymorphism (SNP) markers. A genome-wide association study (GWAS) was performed using the 3VmrMLM model by integrating dual-environment phenotypic data, and four quantitative trait nucleotides (QTNs) significantly associated with resistance to FLS were identified on chromosomes 8 (1), 17 (1), and 20 (2). By the analysis of genomic annotation, functional enrichment, metabolic pathway analyses, haplotype-phenotype association and quantitative real-time PCR (qRT-PCR), Glyma.20G155700 and Glyma.17G070500 are intended to be candidate genes related to soybean resistance to race 7 of FLS. The findings of this study provide insights into the genetic mechanisms underlying resistance to FLS in soybean. The identified molecular markers and candidate genes may provide useful resources for marker-assisted breeding and the development of disease-resistant germplasm.