Glycinin (11S) and β-conglycinin (7S) are important seed storage proteins in soybean [Glycine max (L.) Merr.].A major limitation of soybean seed storage proteins is their low levels of the sulfur-containing amino acids, methionine and cysteine, which are important nutritional components of protein meal. Glycinin contains significantly more S-containing amino acids than does β-conglycinin. Thus, detection of quantitative trait loci (QTL) that govern 11S may provide marker-assisted selection (MAS) opportunities to improve soybean total S-containing amino acids. The objective of this study was to detect and map QTL governing 7S and 11S fractions of soybean seed storage proteins. To achieve this objective, 101 F 6 -derived recombinant inbred lines (RIL) developed from a cross of N87-984-16 × TN93-99 were used. Storage proteins were extracted from all RIL and separated in 10-20% linear gradient polyacrylamide gels. Dried gels were scanned for individual subunits of storage protein with a densitometer equipped with a He-Ne laser light source. Data were converted to concentration for each subunit component and analyzed using SAS software. A significant (P < 0.05) difference among genotypes was found for glycinin and β-conglycinin. A total of 94 polymorphic simple sequence repeat molecular genetic markers were used in screening all RIL. Three QTL for glycinin (Satt461, Satt292, and Satt156) were distributed on linkage group (LG) D2, I, and L, respectively, whereas two QTL for conglycinin (Satt461 and Satt249) were distributed on LG D2 and J. Phenotypic variation explained by individual QTL ranged from 9.5 to 22%. These QTL may provide useful MAS opportunities for improvement of nutritional quality in soybean.Soybean is a major source of protein and amino acids for human and animal feeds in the world (1). However, soy protein is not perfect because of its low levels of the sulfur-containing essential amino acids, methionine and cysteine. Enhancing the concentration of nutritionally essential amino acids in soybean would improve soy meal quality and boost its inclusion in diets for humans and animals.Soybean storage protein has two major fractions, β-conglycinin (7S) and glycinin (11S), accounting for more than 70% of the total proteins (2). β-Conglycinin is a trimer with subunits α, α′, and β, and a M.W. of about 180 kDa. Glycinin is a hexamer with a M.W. of 360 kDa, consisting of acidic and basic subunits. Glycinin constitutes about 35% of the total seed storage protein (3). Glycinin has three to four times more S-containing amino acids (particularly methionine) than does β-conglycinin (4). In addition, the β subunit of conglycinin is known to be void of methionine and cysteine. Hence, the glycinin fraction may be more desirable than the β-conglycinin fraction in developing improved amino acid balance in soy meal. Both 7S and 11S are components of total seed protein, and there is a typical inverse relationship between 7S and 11S concentrations (5). Thus, glycinin can be increased at the expense of β-conglycinin. Mutants ...