Studies on the lipid composition of developing soybeans

Abstract

Studies are reported on changes in fatty acid and lipid class composition in developing soybeans picked at intervals from ca. nine days after flowering to maturity. In the early stages of development of the bean, the lipid was virtually devoid of triglyceride and the major constituents consisted of glycolipids and phospholipids. As the bean developed, there was a rapid synthesis of triglyceride that paralleled the deposition of lipid. Simultaneously, unknown substances which occurred in relatively large amounts in the neutral, as well as the glycolipid and phospholipid, fractions of the immature bean diminished to less than 2% of the total lipid in the mature bean. The glycolipids and phospholipids also increased as the bean developed but at a much slower rate than the triglycerides and became minor components in the mature bean. The major component of the phospholipids in the immature bean was phosphatidic acid. It decreased as the phosphatidyl choline, phosphatidyl ethanolamine, and phosphatidyl inositol, as well as triglyceride, increased. The major component of the glycolipid fraction in the early stages of the development of the bean had the same migration pattern on two-dimensional thin layer chromatography as phosphatidic acid and gave a positive test for phosphorus; it also gave a positive test for glycolipids and was separated completely from phosphatidic acid and other phospholipids by column chromatography. It also decreased as the bean developed. Changes also occurred in the fatty acid composition of the developing bean. The percentage of saturated fatty acids decreased rapidly in the early stages of the development of the bean; oleic and linoleic increased rapidly as the bean developed. Linolenic acid increased rapidly to a maximum concentration in the early stages of the development of the bean and then gradually decreased as the bean matured.