Desaturation of oleate-[14C] in leaves of barley

Etiolated barley leaves when exposed to light desaturate oleate-¹⁴C] to linoleate. The production of substantial amounts of radioactive linolenate was found only in very young, tightly rolled leaves. In oleate-¹⁴C] pulse experiments, radioactive linolenate first appeared in phosphatidylcholine (PC) and only after a lag period did it begin to accumulate in monogalactosyldiacylglycerol (MGDG). The results indicate that in young, immature barley leaves linolenate is synthesized from oleate on the parent lipid, PC, and is then transferred to MGDG.