Seed Protein Genetics Linked with Nitrogen and Phosphorus Translocation Efficiency in Soybean

Abstract

Soybean (Glycine max (L.) Merr.) is an important nutritional crop with high seed protein content. Production of high protein concentrations relies on sufficient nutrient supplies, especially of nitrogen (N) and phosphorus (P). Although the genetic basis for seed quality traits has been well studied, little information exists on any genetic connections between seed quality and nutrient supplies in soybean. Here, a recombinant inbred line (RIL) population of 179 progeny was generated using HC6 and JD17 as parents contrasting in seed quality and N and P translocation efficiencies. Seed protein and N and P translocation efficiencies were higher in HC6 than in JD17. Meanwhile, positive correlations were observed between seed protein content and translocation efficiency of N and P in RILs, implying that high N and P translocation efficiencies might facilitate seed protein accumulation. A genetic map was constructed using 5250 SNP markers covering a genetic distance of 3154.83 cM. A total of 6 loci for quality and 13 loci for N and P translocation efficiency were detected. Among them, two fragments on chromosome 6 and chromosome 20 contained multiple significant markers for both quality and N and P translocation efficiencies, with the respective observed LOD values ranging from 2.98 to 5.61, and 3.01 to 11.91, while the respective PVE values ranged from 8.2% to 13.9%, and 8.3% to 28.0%. Interestingly, one significant locus on chromosome 20 appears to be the product of a transposable element (TE) InDel in Glyma.20G085100, with progeny lacking the TE also exhibiting higher N and P translocation efficiencies, along with higher seed protein contents. Taken together, these results provide genetic evidence that increasing N and P translocation efficiencies may lead to increasing protein contents in soybean seeds. Furthermore, a TE InDel may be used as a genetic marker for breeding elite soybean cultivars with high protein content and N and P translocation efficiencies.