Observations on the biosynthesis of [alpha]-eleostearic and vernolic acids and the accumulation of petroselinic acid in somatic carrot embryos
Developing somatic embryos of carrots accumulated up to 24% petroselinate of total fatty acids, most of which was incorporated into triacylglycerols. Both triacylglycerol and petroselinate accumulation in the embryos were increased by addition of abscisic acid to the culture medium. The novel phenylethyl esters of the fatty acids were used to separate petroselinate from oleate both by gas chromatography and high performance liquid chromatography. This derivative offers the fastest and most efficient method for petroselinate analysis among the published procedures;The biosynthesis of vernolic acid in the developing seed of Vernonia galamensis was explored by using (1-14C) acetate in vivo labeling in time-course and pulse-chase experiments. The results suggested that vernolate was synthesized from linoleate on phosphatidylcholine;The biosynthesis of [alpha]-eleostearic acid in the developing seed of Momordica charantia was investigated by in vivo radioactive labeling using sodium (1-14C) acetate, ammonium (1-14C) oleate and ammonium (1-14C) linoleate. Time-course and pulse-chase experiments were conducted. The results indicated that [alpha]-eleostearate was synthesized from linoleate on phosphatidylcholine. The biosynthesis of [alpha]-eleostearate in vitro was achieved by incubation of a cell-free homogenate of the developing seed with ammonium (1-14C) linoleate. Among the cofactors investigated, NADH, ATP, CoA and NADPH stimulated and DTT inhibited the biosynthesis of [alpha]-eleostearic acid. The optimum pH for in vitro incubation was 5.5.