Desaturase Genes Expression and Fatty Acid Composition of Pleurotus ostreatus in Response to Zinc and Iron

The influence of ZnSO4, FeSO4, ZnO, and Fe2O3 at 80 µM on the expression of desaturase genes and fatty acid composition of Pleurotus ostreatus was investigated. Fatty acid was extracted by lipid extraction and methylation procedure using acidic methanol: normal saline: hexane solution followed by gas chromatography-mass spectrometry (GC-MS). The most prominent fatty acids in P. ostreatus were linoleic acid (44.7%), palmitic acid (8.6%), oleic acid (8.5%), stearic acid (2.9%), pentadecanoic acid (2.6%) and heptadecanoic acid (2.3%). ZnO strongly and Fe2O3 slightly lead a decrease in unsaturated fatty acid (UFA), polyunsaturated fatty acid (PUFA) and omega-6 and an increase in the monounsaturated fatty acid (MUFA), omega-7 and omega-9 content. Accordingly, our results considerably confirmed the different effects of ZnSO4 and ZnO on fatty acid content. These differential effects for FeSO4 and Fe2O3 were not significant. Δ9-desaturase and Δ12-desaturase expression but not Δ15-desaturase were upregulated in the seeds cultured in media containing ZnO and Fe2O3.