Identification of quantitative trait loci associated with salt tolerance during seedling growth in soybean (Glycine max L.)

Salt stress is an important factor affecting the growth and development of soybean. The inheritance and expression of traits associated with salt tolerance during the seedling stage are complex. The present study was conducted to identify quantitative trait loci (QTLs) associated with salt tolerance during seedling growth in soybean. Field and greenhouse experiments were conducted to evaluate 184 recombinant inbred lines (RILs) derived from a cross between Kefeng No. 1 and Nannong 1138-2 for salt tolerance and QTLs that are associated with salt tolerance. The molecular map of this RIL population, covering 2625.9 cM of the genome, converged into 24 linkage groups and consisted of 221 SSR markers and 1 disease-resistant gene (Rsc-7). QTL mapping was conducted using WinQTLCart. Eight putative QTLs significantly associated with salt tolerance were identified. One QTL was identified both in field and greenhouse experiments. In the field, salt tolerance was assessed (tolerance rating, TR) visually on a 0 (death) to 5 (unaffected by salt stress) scale. Three QTLs were detected on two linkage groups explaining 7.1-19.7% of the total phenotypic variance for salt tolerance. In the greenhouse, plant survival days (PSD) and percentage of plant survival (PPS) under salt stress were measured. Six QTLs were detected on six linkage groups, and explained 7.8-19.2% of total phenotypic variation for salt tolerance. A major QTL was identified between markers Sat_164 and Sat_358 on linkage group G in both the field and greenhouse. This QTL qppsN.1 was identified in the same location as a salt tolerance QTL previously reported in soybean. The detection of new QTLs will provide important information for marker-assisted selection (MAS) and further genetic studies on salt tolerance in soybean.