Lipoxygenase Pathways in Diatoms: Occurrence and Correlation with Grazer Toxicity in Four Benthic Species.

Oxygenated derivatives of fatty acids, collectively called oxylipins, are a highly diverse family of lipoxygenase (LOX) products well described in planktonic diatoms. Here we report the first investigation of these molecules in four benthic diatoms, , , , and sp. isolated from the leaves of the seagrass from the Gulf of Naples. Analysis by hyphenated MS techniques revealed that , , and produce several polyunsaturated aldehydes (PUAs) and linear oxygenated fatty acids (LOFAs) related to the products of LOX pathways in planktonic species. sp. also produced other unidentified fatty acid derivatives that are not related to LOX metabolism. The levels and composition of oxylipins in the benthic species match their negative effects on the reproductive success in the sea urchin . In agreement with this correlation, the most toxic species revealed the same LOX pathways of and , two bloom-forming planktonic diatoms that affect copepod reproduction. Overall, our data highlight for the first time a major role of oxylipins, namely LOFAs, as info-chemicals for benthic diatoms, and open new perspectives in the study of the structuring of benthic communities.