The present disclosure relates to the isolation, purification, and characterization of a diacylglycerol acyltransferase 2 (DGAT2), and genes encoding DGAT2, from algae. DGAT2 can incorporate very long chain polyunsaturated fatty acids in to triacylglycerol more efficiently than DGAT1. The disclosure concerns methods of regulating seed oil content, fatty acid synthesis and fatty acid composition using the DGAT2 gene and to tissues and plants transformed with the gene. The disclosure also relates to transgenic plants, plant tissues and plant seeds having a genome containing an introduced DNA sequence of the disclosure, and a method of producing such plants and plant seeds.
