Genetic architecture of biofortification traits in soybean (Glycine max L. Merr.) revealed through association analysis and linkage mapping

Seed mineral elements are essential not only for seed germination and seedling morphological formation but also for human health. The genetic dissection of seed mineral accumulation is important for mineral biofortification in soybean. However, the molecular mechanisms controlling mineral element accumulation are genetically complex because a number of genetic loci are involved in the metabolic pathways of mineral accumulation in seeds. The objective of this study was to detect the genetic loci for mineral concentrations in soybean seeds, including calcium (Ca), magnesium (Mg), iron (Fe), zinc (Zn) and phosphorus (P). Quantitative trait loci (QTL) mapping for the corresponding traits was performed in 184 recombinant inbred lines (RILs) and 219 cultivated soybean accessions. The data for each year and the average across 2 years were used for identification and mapping of QTL controlling seed mineral concentrations. Linkage mapping in the RILs identified totally 35 significant QTL for the five seed mineral concentrations in three cases, some of which were co-localized. Association mapping in the 219 accessions detected 28 single-nucleotide polymorphisms associated with the seed mineral concentrations. Among these, BARC-018099-02516, which was associated with seed Zn concentration, was located close to qZn-11-2. There were 20 putative mineral-related genes in interesting regions of mineral QTL. Three QTL for seed weight were mapped in the RILs, two QTL for seed weight were co-localized with seed Ca, Zn and P concentration QTL which anchored to the same region on chromosome 11. These results will provide a profound understanding of the genetic basis for seed mineral accumulation in soybean seeds and the foundation for mineral biofortification through marker-assisted selection breeding.