Relationships between Soybean Seed Cell Wall Polysaccharides, Yield, and Seed Traits

Seed cell wall polysaccharides (CWPs) represent a significant portion of seed dry matter (DM) in soybean [Glycine max (L.) Merr.]. To further investigate the role of seed CWP in determining seed traits, relationships were examined among monosaccharide constituents of CWP and between CWP, yield, maturity, seed weight, and protein and oil content using principal component (PC) analysis in 13 Minnesota-adapted cultivars. Monosaccharide data were used to form PCs. Principal Component 1 mainly described pectin polysaccharides composed of rhamnose and galactose and was negatively correlated with the sum of protein and oil content (protein + oil) (r = −0.58). Cellulose, hemicellulose, and arabinose-containing polysaccharides as described by PC2 were negatively correlated with yield (r = −0.59), suggesting lower seed content in these CWP relates to an increase in yield. Seed arabinose:galactose (Ara:Gal) ratio was negatively correlated with yield and maturity and may be an indicator of the average stage of seed cell wall development for a cultivar at maturity. Principal Components 2, 3, and 4 combined to form a stepwise regression equation (R2 = 0.69) for seed weight with PC4 providing the most weight in the equation. This equation implicates linear and backbone polysaccharides as being most important in relation to seed weight. Thus, individual polysaccharide types were correlated with either yield, protein + oil, or seed weight. Lower seed content of CWP was correlated with beneficial changes in seed traits, suggesting that reducing CWP content may provide an additional seed trait improvement.