Molecular insights into the EgFAD gene family driving unsaturated fatty acid formation in oil palm

The enhancement of unsaturated fatty acid (UFA) content in palm oil is essential for improving its nutritional profile and broadening its market appeal. Fatty acid desaturases (FADs), which catalyze the desaturation of saturated fatty acids (SFAs) to UFAs, play a pivotal role in plant lipid metabolism. In this study, a comprehensive genome-wide analysis was conducted to identify and characterize members of the FAD gene family in oil palm (Elaeis guineensis Jacq.). A total of eleven EgFAD genes were identified and categorized into five distinct subfamilies: EgDES, EgSLD, EgFAD2, EgFAD6, and EgFAD7. Genes within each subfamily displayed conserved structural features, motif compositions, subcellular localization profiles, and predicted protein architectures. To elucidate the regulatory roles of EgFAD genes in UFA biosynthesis, transcriptomic and metabolomic datasets were integrated from two oil palm varieties with contrasting UFA levels—high-UFA (MS) and low-UFA (MT) across three fruit developmental stages (95, 125, and 185 days after pollination). Correlation analyses revealed that the FAD2/6/7 gene cluster is closely associated with the modulation of C18 UFA composition via dynamic gene expression patterns. Among them, EgFAD2.1 expression showed the strongest positive correlation with oleic acid content and plays a central role in catalyzing the desaturation of oleic acid into linoleic acid. Furthermore, through the prediction of transcription factors and their binding sites, transcriptional regulatory and hormone signaling networks were constructed. These networks suggest that phytohormonal signals may influence fatty acid desaturation by regulating the expression of EgFAD genes.These findings provide novel insights into the molecular mechanisms governing fatty acid metabolism in oil palm and establish a foundational framework for future genetic improvement efforts aimed at enhancing UFA content through targeted manipulation of FAD genes.