The biosynthesis of long-chain saturated and unsaturated fatty acids in isolated plant leaves

Abstract 1. 1. The incorporation of labelled acetic, octanoic, decanoic, dodecanoic, tetradecanoic, hexadecanoic, octadecanoic and 9-octadecenoic acids into the saturated and unsaturated fatty acids of lipids from isolated leaves (mainly Ricinus communis ) is described. 2. 2. With the exception of hexadecanoic and octadecanoic acids all these labelled compounds acr as precursors of oleic, linoleic and linolenic acids. 3. 3. Hexadecanoic and octadecanoic acids are incorporated into leaf lipids. 4. 4. In the absence of oxygen no oleic acid is synthesized. 5. 5. Two separate pools of the longer-chain fatty acids are suggested. In one myristic acid is converted to palmitic and stearic acids which are then esterified to give galactolipid and phosopholipid. In the second pool myristic acid is converted to palmatic acid, then to stearic acid and finally to oleic acid. Only the latter is freely available for esterification to combined lipids or for conversion to linoleic and linolenic acids.