Fatty Acid Compositions in Newly Differentiated Tissues of Soybean Seedlings

Six soybean genotypes with various fatty acid compositions were allowed to germinate in sand under a greenhouse. Seedlings were picked up after 5, 6, 7, 8, 10, and 12 days and dried under sun. During germination, the fatty acid composition of cotyledons changed slightly, but those of all newly differentiated tissues, including root, hypocotyl, epicotyl, unifoliate, and trifoliate, changed dramatically, especially within the first 5 days. Although lipids from these tissues contained the five major fatty acids found in original seeds, their fatty acid compositions were totally different from that of the seed: higher in palmitic, linolenic, and stearic acid and lower in oleic and linoleic acid. There existed a distinct difference in fatty acid compositions between the young tissues below and those above cotyledons in the seedling. Furthermore, all new tissues conserved their fatty acid compositions regardless of genotypes, which may be explained by conservation of membrane lipids predominating in these tissues.