CHANGES IN STEROLS AND FATTY-ACIDS OF BUCKWHEAT ENDOSPERM AND EMBRYO DURING SEED DEVELOPMENT

Buckwheat (Fagopyrum esculentum Moench) plants produce a low grain yield because of a low incidence of seed set. As part of a study of seed set and abortion, sterols and fatty acids were extracted from developing embryo and endosperm tissues 6-20 days after pollination (DAP) and analyzed by gas chromatography. The most abundant sterol was beta-sitosterol, which made up 70% of the total sterols. Other sterols were campesterol, an unknown, and traces of stigmasterol. Total sterols in embryos were 2.1 +/- 0.05 g/kg of dry weight and in endosperm tissues were 0.55 +/- 0.02 g/kg at 20 DAP; total fatty acids in embryo and endosperm lipids were 123 +/- 8 and 22 +/- 3 g/kg, respectively. Linoleic, oleic, and palmitic accounted for 88% of the total fatty acids at 20 DAP. At 6-10 DAP, 60-80% of the total fatty acids were saturated, mostly palmitic acid, but at 12-20 DAP, 65-80% were unsaturated, mostly linoleic and oleic. The rapid transition at 10-12 DAP was associated with rapid embryo growth and a 10-fold increase in storage lipids. Palmitic was 3-5 times more abundant than any other fatty acid at 6 DAP when myristic acid concentration was highest. Long-chain fatty acids (C20:0, C22:0, and C20:1) accumulated late in development to less than 7% of the total fatty acids.