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 soy bean genotypes were analyzed by gas chromatography. Relative percentag es of fatty acids were homogeneous within cotyledons but varied greatl y among structural parts. The axis had highest percentage of polyunsat urated fatty acids, whereas the coat had highest percentage of saturat ed fatty acids. Due to the cotyledons representing the largest proport ion, the fatty acid composition of cotyledons represented that of the whole seed, suggesting that slicing a portion of cotyledons for breedi ng screen of fatty acids is a reliable sampling technique. Furthermore , regardless of the great variation in fatty acid profile of the six g enotypes selected, the ratio in relative percentage of an individual f atty acid between the axis and cotyledons was highly conserved, implyi ng that (1) events of lipid metabolism in maturing seeds may be correl ated between axis and cotyledons, and (2) given a fatty acid compositi on of one tissue, one can predict that of the other.