Bioinformatics Analysis and Functional Verification of PlDGAT2 Gene Associated with Triacylglycerol Biosynthesis in Paeonia lactiflora Pall.

Seeds of Paeonia lactiflora Pall. ‘Hangshao’ contain over 20% oil, of which more than 90% are unsaturated fatty acids, showing its high potential as an oil crop. Triacylglycerol (TAG) is the main storage form of fatty acids, and diacylglycerol acyltransferase 2 (DGAT2) is a key enzyme in TAG biosynthesis. In this study, the full-length cDNA of PlDGAT2 (326 amino acids) was cloned. Subcellular localization assays further indicated that it localized in the endoplasmic reticulum. Functional verification showed that silencing PlDGAT2 in herbaceous peony decreased the level of total fatty acids, palmitic acid (C16:0, PA) and α-linolenic acid (C18:3, ALA), but increased linoleic acid (C18:2, LA) in leaves. Overexpressing PlDGAT2 in tobacco elevated the content of total fatty acids, PA, and ALA in seeds, while also enlarging the seed sizes, but it reduced the LA content in tobacco seeds. This study suggests that PlDGAT2 contributes to the accumulation of ALA and total fatty acids, offering a potential gene target for improving the oil quality of herbaceous peony seeds.