Biosynthesis of Polyunsaturated Short Chain Aldehydes in the Diatom Thalassiosira rotula

The diatom Thalassiosira rotula releases polyunsaturated short chain aldehydes (PUA) such as 2E,4Z,7-octatrienal (7a) and 2E,4Z,7Z-decatrienal (3a) upon wounding. Using labeling experiments and synthetic standards, we demonstrate that the mechanism of fatty acid transformation does not follow established lipoxygenase/hydroperoxide lyase pathways known from higher plants or mammals but rather relies on a unique transformation of polyunsaturated hydroperoxy fatty acids. These intermediates are transformed to PUA and short chain hydroxylated fatty acids, which are novel oxylipins.