Monitoring changes of lipid composition in durum wheat during grain development

The lipid fraction of durum wheat (Triticum turgidum ssp. durum (Desf.) Husn.), cultivar Svevo, was characterized during grain maturation. Growing grain kernels were harvested at five key stages of development between 5 and 30 days post anthesis (dpa). Lipid evolution was assessed during kernel filling by gas chromatography-mass spectrometry (GC-MS) analysis of triacylglycerols and methylated free fatty acids (FFA) as well as by ultra-high performance liquid chromatography coupled to high resolution electrospray ionization tandem mass spectrometry (UHPLC-HRESI-MS/MS) lipid analysis. Major triacylglycerols (TAG) were detected already at early developmental stages, albeit at low abundance. The decrease of FFA during kernel filling corresponded to accumulation of predominantly linoleate (C18:2n6)-containing C52 and C54 TAG. Fatty acid composition of polar lipids including phospholipids and galactolipids also showed the progressive dominance of linoleate, typically since two weeks after anthesis. Conversely, minor sphingolipids (ceramides and glycosylceramides) were constituted mainly by saturated long chain FA, also oxygenated, combined with a restricted set of sphingoid bases, and might play a signaling role during grain development.