Involved in triacylglycerol (TAG) synthesis. Catalyzes the acylation of the sn-3 hydroxy group of sn-1,2-diacylglycerol using acyl-CoA (PubMed:23770095, PubMed:24663078). Can use oleoyl-CoA, linoleoyl-CoA and linolenoyl-CoA as substrates. Has substrate preference for linolenoyl-CoA or oleoyl-CoA compared to linoleoyl-CoA (PubMed:23770095). a 1,2-diacyl-sn-glycerol + an acyl-CoA = a triacyl-sn-glycerol + CoA (9Z)-octadecenoyl-CoA + 1,2-dihexanoyl-sn-glycerol = 1,2-dihexanoyl-3-(9Z-octadecenoyl)-sn-glycerol + CoA Glycerolipid metabolism; triacylglycerol biosynthesis. Ubiquitous. Lower levels in seeds than in other tissues. Expressed in embryo and root meristematic cells (PubMed:23042274). No decrease in oil content. Belongs to the diacylglycerol acyltransferase family.