Genetic diversity and association analysis of protein and oil content in food-grade soybeans from Asia and the United States

P>Food-grade soybean has generated tremendous public interests in various soyfoods including tofu, soymilk, natto and edamame because of their nutritional value and health benefits. In this study, genetic diversity and association analysis were performed among 105 food-grade soybean genotypes using 65 simple sequence repeat (SSR) markers distributed on 20 soybean chromosomes. Based on the SSR marker data, the 105 soybean genotypes were divided into four clusters with six sub-groups. A negative correlation was obtained between protein and oil content (r = -0.67). Thirteen SSR markers distributed on 11 chromosomes were identified to be significantly associated with oil content (P = 0.001 and R2% = 14.4-43.5) and 19 SSR markers distributed on 14 chromosomes with protein content (P = 0.001, R2% = 14.3-45.6). Twelve of the SSR markers were associated with both protein and oil QTL (quantitative trait loci). Results from this research will be facilitatory for breeders to select parents for crossing and use marker-assisted selection in food-grade soybean breeding and to map QTL for protein and oil content in soybean.