Association Mapping of Genomic Loci Controlling Salt Tolerance in a Diverse Panel of Soybean Germplasm Accessions.

Salinity is one of the major abiotic stresses that adversely affects productivity and quality in several crops including soybean [Glycine max (L.) Merr.]. Conventional genetic studies have commonly utilized bi-parental mapping populations to identify and characterize genomic region(s) associated with tolerance to salinity. Even though this strategy has successfully mapped major loci on different chromosomes (Chr.), it has limitations to capture allelic diversity and genomic resolution in parental lines. In this study, a genome-wide association study (GWAS) was performed to detect and map genomic regions for salt tolerance in a diverse panel of over 350 exotic soybean plant introductions (PIs), consisting of both cultivated (Glycine max) and wild soybean (Glycine soja). Over 37,000 single nucleotide polymorphism (SNP) markers with minor allele frequency (MAF) ≥ 0.5, generated by the SoySNP50K iSelect BeadChip were utilized for analysis. The GWAS identified a major locus on Chr. 3 (p-value = 8.08E-34), which was consistently mapped at the same genomic position as the known locus of previous studies. A second minor locus was identified and mapped on Chr. 5 (p-value = 5.39E-06). It was speculated that it could be a novel locus for salinity tolerance in this panel of exotic germplasm. Several candidate genes along with significantly associated SNPs will be helpful to reveal the molecular mechanism involved in salt tolerance and also useful for marker-assisted selection in soybean molecular breeding programs.