The lipids of germinating wheat

Abstract

The evolution of the fatty acids present in the lipíd classes of different structural parts of the wheat kernel during germination in the dark has been investigated. Lipid was extracted with chloroform: methanol (2: 1), washed according to Folch et al., and fractionated by preparative TLC. Free fatty acids (FFA), as well as those present in triglycerides (TGFA), diglycerides (DGFA), monoglycerides (MGFA), polar lipids (PLFA), and the total lipid extract (TFA) have been determinated by GLC. In all parts studied, the PLFA pattern is rather constant and, the rootlets excepted, so is their content in the tissues (% of dry matter). Observed changes in lipid content and composition are mainly due to the glyceride fractions. In the degermed seed, lipid is lost at a faster relative rate than non-fat dry matter. The TGFA pattern shows a constant proportion of palmitic (C,6.0), stearic (C18:0), and linolenic (C81¡3), but that of linoleic (C18:2), increases at the expense of oleic (C18;1), as germination proceeds. A net loss of lipid followed by a net synthesis is observed in the germ during germination. A drastic change in TGFA pattern takes place during the first half of the process. The data suggests that the original triglycerides present in the germ are catabolized very rapidly while new triglycerides with a different fatty acid pattern are synthesized in the growing tissues.