Regional distribution in the fatty acids of triacylglycerols and phospholipids within soybean seeds (Glycine max L.)

The fatty acid distribution of triacylglycerols (TAG) and major phospholipids (PL) within soybean seeds (Glycine max L.) was investigated in relation to their tocopherol contents. The lipids extracted from four cultivars were separated by thin-layer chromatography into seven fractions. Tocopherols were predominantly detected in the axis, followed by cotyledons and seed coat. The major lipid components were TAG and PL, while hydrocarbons, steryl esters, free fatty acids and diacylglycerols (sn.-1,3 and sn-1,2) were also present in minor proportions. With a few exceptions, the dominant PL components were phosphatidylcholine, followed by phosphatidylethanolamine or phosphatidylinositiol. Significant differences (p <0.05) in fatty acid distribution existed when different soybean cultivars were examined. However, the principal characteristics of the fatty acid distribution in the TAG were evident among four cultivars; unsaturated fatty acids were predominantly concentrated in the sn-2 position, and saturated fatty acids primarily occupied the sn-1 or sn-3 position in the oils of the soybeans.