Fatty Acid Composition within Each Structural Part and Section of a Soybean Seed

Seed coat, axis, sections of cotyledons, and the whole seed of six soybean genotypes were analyzed by gas chromatography. Relative percentages of fatty acids were homogeneous within cotyledons but varied greatly among structural parts. The axis had highest percentage of polyunsaturated fatty acids, whereas the coat had highest percentage of saturated fatty acids. Due to the cotyledons representing the largest proportion, the fatty acid composition of cotyledons represented that of the whole seed, suggesting that slicing a portion of cotyledons for breeding screen of fatty acids is a reliable sampling technique. Furthermore, regardless of the great variation in fatty acid profile of the six genotypes selected, the ratio in relative percentage of an individual fatty acid between the axis and cotyledons was highly conserved, implying that (1) events of lipid metabolism in maturing seeds may be correlated between axis and cotyledons, and (2) given a fatty acid composition of one tissue, one can predict that of the other.