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>Genetic analysis of food-grade soybeans and identification of quantitative trait loci (QTL) for seed hardness and calcium content in soybean.
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Genetic analysis of food-grade soybeans and identification of quantitative trait loci (QTL) for seed hardness and calcium content in soybean.
The description of genotypes and evaluation of genetic diversity provide genetic information and strategies to utilize the diverse gene pools in current food-grade breeding programs. Nine seed-quality traits were assessed among 105 small- and large-seeded soybeans from the United States and Asia. U.S. small-seeded soybeans exhibited more phenotypic diversity than Asian small-seeded accessions, whereas U.S. large-seeded soybeans had less phenotypic diversity than Asian large-seeded soybeans. Protein content, stone seed ratio, and 100-seed weight were the major traits that distinguished food-grade soybeans. Genetic distance within U.S. and Asian food-grade soybean accessions was similar, indicating that U.S. food-grade soybeans had a relatively high level of genetic diversity when compared to U.S. yield-based genotypes. The high levels of genetic diversity in food-grade soybeans are probably due to exotic plant introductions, diverse parentage, and the multiple selection criteria for specialty soybeans. This diverse germplasm may serve as a valuable gene pool for the development of conventional and specialty soybeans.;Seed hardness and calcium content are very important for processing and quality of food-grade soybeans. The objective of the study was to use quantitative trait loci (QTL) analysis to identify genomic regions significantly associated with calcium content and seed hardness in segregating F2-derived populations from a high calcium/hard x low calcium/soft cross. A genetic linkage map covering 1421.8 cM for both calcium content and seed hardness was established using 148 single sequence repeat (SSR) markers, 15 of which were new for the current public soybean genetic linkage map. Three QTL (labeled as Ca1, Ca2, and Ca3) were identified and accounted for 16.4, 9.4, and 7.3% of calcium content variation, respectively. No significant epistatic effects were noticed among the three QTL. Two QTL (labeled as Ha1 and Ha2) for seed hardness were identified that explained 12.7% and 36.1% of phenotypic variation, respectively. A dominance-by-dominance interaction was detected between Ha1 and Ha2 and explained 7.9% of the phenotypic variance. These QTL can be used for marker-assistant selection (MAS) in developing elite specialty cultivars with optimum calcium content and seed hardness.
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