Alteration of the fatty acid composition of Brassica napus L. via overexpression of phospholipid: Diacylglycerol acyltransferase 1 from Sapium sebiferum (L.) Roxb

Sapium sebiferum (L.) Roxb. plays an important role in traditional Chinese medicine and is one of major woody oil tree in China. Phospholipid: diacylglycerol acyltransferase 1 (PDAT1), as an important catalytic enzyme for the formation of triacylglycerol (TAG), is mainly responsible for the transfer of an acyl group from the sn-2 position of phospholipids to the sn-3 position of sn-1, 2-diacylglycerol (DAG) to produce TAG and sn-1 lysophospholipids. The importance of PDAT1 in triacylglycerol biosynthesis has been illustrated in previous research, and at least 67 PDAT1 sequences have been identified from 31 organisms. However, little is known about the gene encoding PDAT1 in S. sebiferum (SsPDAT1), which is involved in seed oil biosynthesis. To explore the functional characteristics of SsPDAT1, we cloned and analyzed the full-length cDNA in the coding region of SsPDAT1, which consists of 2040 bp and encodes a putative protein of 680 amino acid (aa) residues. Thin-layer chromatography (TLC) analysis showed that recombinant SsPDAT1 could restore TAG accumulation in TAG-deficient mutant yeast (Saccharomyces cerevisiae) H1246, which revealed the enzyme activity of SsPDAT1. Moreover, transgenic Brassica napus L. W10 plants overexpressing SsPDAT1 showed significant increases of 19.6-28.9 % in linoleic acid levels but decreases of 27.3-37.1 % in linolenic acid. Furthermore, the total oil content increased by 8.1 %-10.8 % in SsPDAT1 transgenic seeds. These results confirmed the role of SsPDAT1 in stabilizing oil biosynthesis and suggested that SsPDAT1 could be exploitable to specifically regulate the oil composition of plants. These experimental results provide a new concept that may enable the industrial development of plants with high-linoleic-acid oil through overexpression of SsPDAT1 in S. sebiferum L.

Keywords: Brassica napus L.; Oil composition; Phospholipid: diacylglycerol acyltransferase 1; Sapium sebiferum (L.) Roxb..