Objective FAD enzymes introduce double bonds at specific positions in fatty acids, converting saturated fatty acids into unsaturated fatty acids, playing crucial roles in plant growth, development, and stress responses. This study aimed to systematically identify the FAD gene family in Panax ginseng and verify the function of PgFAD2-56, so as to elucidate the functions and stress response mechanisms of ginseng FAD genes. Methods Using bioinformatics approaches, 98 PgFAD genes were identified from the P. ginseng T2T genome, and their physicochemical properties, phylogenetic relationships, chromosomal localization, gene structures, conserved motifs, cis-acting regulatory elements, collinearity, and expression patterns under stress conditions were analyzed. Molecular docking was performed to predict the binding affinity of highly expressed FAD2 proteins with oleic acid, and the function of PgFAD2-56 was verified using a yeast heterologous expression system. Results The results showed that the 98 PgFAD genes could be classified into six subfamilies (ADS, SLD, FAD3/FAD7/FAD8, FAD6, FAD2, and FAB) based on amino acid sequence similarity, which was consistently supported by their gene structures and conserved motifs. Numerous hormone- and stress-responsive cis-acting elements and transcription factor binding sites (TFBSs) were identified in the promoters of PgFAD genes. Collinearity analysis revealed significant expansion of the FAD2 subfamily in P. ginseng. Gene expression analysis demonstrated that some PgFADs displayed significant differential expression under stress conditions. Molecular docking indicated that FAD2-56 exhibited the lowest binding energy with oleic acid (−6.5 kcal/mol) among the highly expressed FAD2 proteins. Heterologous expression in yeast confirmed that PgFAD2-56 altered fatty acid composition by producing linoleic acid and enhanced cold stress resistance. Conclusion This study demonstrates that the ginseng FAD gene family exhibits strong subfamily specificity and plays a vital role in stress resistance, with the expansion of the FAD2 subfamily and functional characterization of PgFAD2-56 providing potential targets for stress-resistant molecular breeding in P. ginseng.

Panax ginseng C. A. Mey.  /  whole genome identification  /  FAD gene family  /  unsaturated fatty acids  /  bioinformatics analysis