Quantitative trait loci for β‐conglycinin (7S) and glycinin (11S) fractions of soybean storage protein

Abstract

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 ...

Identification of new QTLs for seed mineral, cysteine, and methionine concentrations in soybean [Glycine max (L.) Merr.]

“…Co-localization of QTLs might highlight genes involved in uptake, transport, trafficking, and sequestration, which may function for multiple minerals (Clemens 2001;Vreugdenhil et al 2004). Two QTLs out of 40 identified in this study using individual analysis of each mapping population co-located with previously detected QTLs, both for N on chromosomes 14 and 15, respectively (Panthee et al 2004b). Seed weight QTL in previous studies (Csanádi et al 2001;Hyten et al 2004;Maughan et al 1996;Mian et al 1996;Orf et al 1999;Panthee et al 2005;Specht et al 2001) co-located with several mineral QTLs in this study, suggesting the possibility that seed mass could influence seed mineral concentration (Cakmak et al 2000 andImtiaz et al 2003).…”

Antioxidant Capacity of Alcalase Hydrolysates and Protein Profiles of Two Conventional and Seven Low Glycinin Soybean Cultivars

“…Characterization of soybean cultivars The major storage proteins present in soybean are trimer BC and hexamer GL which account for 50-70% of total seed proteins [29]. BC has a molecular mass of 150-200 kDa with three major subunits α, α' and β [30]; whereas the molecular mass of GL is between 320-375 kDa with five major subunits A1aB2, A2B1a, A1bB1b, A5A4B3 and A3B4 [31].…”

Assessing Glycinin (11S) and β‐Conglycinin (7S) Fractions of Soybean Storage Protein by Near‐Infrared Spectroscopy

“…Unlike 7S, it is not clear which of the glycinin polypeptides contains more sulfur-containing amino acids. Therefore, as suggested by Panthee et al [8], the glycinin fraction may be more desirable than b-conglycinin in improving the amino acid balance in soybeans. Considering that there is a typical inverse relationship between 7S and 11S concentrations, glycinin can be increased at the expense of b-conglycinin.…”

“…Glycerol and bromphenol blue were added to each sample to achieve a final concentration of 10 and 0.025%, respectively. Additional details are provided in Panthee et al [8].…”