Overexpression of a FAD3 Desaturase Increases Synthesis of a Polymethylene‐Interrupted Dienoic Fatty Acid in Seeds of Arabidopsis thaliana L.

A cDNA encoding the Arabidopsis extraplastidic linoleate desaturase (FAD3) was overexpressed in the seeds of wild‐type Arabidopsis and in a mutant line that accumulates high levels of oleic acid. In the transformed wild‐type plants, linolenic acid (18:3Δ9,12,15) increased from 19% to nearly 40% of total seed fatty acids, with a corresponding decrease in linoleate content (18:2Δ9,12). In the high oleate mutant, a large increase in the level of a fatty acid identified by gas‐chromatography/mass‐spectrometry as mangiferic acid (18:2Δ9,15) was observed. The results demonstrate that the polymethylene‐interrupted dienoic fatty acid, mangiferic acid, can be produced in seed oil through the overexpression of a fatty acid n‐3 desaturase.