Functional heterologous expression of a lysophosphatidic acid acyltransferase from coconut (Cocos nucifera L.) endosperm in Saccharomyces cerevisiae and Nicotiana tabacum

Abstract

The unique properties of oils from the coconut (Cocos nucifera L.) endosperm, which contains a remarkable amount of saturated medium-chain fatty acids (MCFAs), has garnered significant attention because of the increasing daily demand for these fatty acids. In this paper, lyso-phosphatidic acid acyltransferase (LPAAT), which can esterify acyl-CoA into the sn-2 position of the glycerol backbone during the triacylglycerol (TAG) biosynthesis, has been isolated from coconut endosperm, designated CnLPAAT. Quantitative real-time PCR showed that the CnLPAAT transcript was present in both leaves and endosperms, with the higher level in mature leaves, and the transcript level was constant during coconut endosperm development. Heterologous expression in yeast was used to confirm the in vivo function of CnLPAAT. The fatty acid analysis showed that the levels of C12:0 and C14:0 in a CnLPAAT-pYES2 transformant increased significantly compared with a pYES2 transformant. Additionally, to detect the effect of CnLPAAT expression in plants, it was heterologously overexpressed in transgenic tobacco (Nicotiana tabacum L.) under the control of the seed-specific napin promoter. The transcript level of CnLPAAT varied 28-fold among different transgenic lines, with 11 lines displaying detectable levels of CnLPAAT expression. However, an analysis of the fatty acid composition of transgenic tobacco seeds showed that the levels of C12:0 and C14:0 decreased diversely in comparison with untransformed tobacco plants. These findings provide new insights into the activities of CnLPAAT and assist in genetically applying this functional mechanism in other plants to accumulate high levels of MCFAs.