Multigene engineering of medium-chain fatty acid biosynthesis in transgenicArabidopsis thalianaby aCre/LoxPmultigene expression system

Medium-chain fatty acids (MCFAs) are an ideal feedstock for biodiesel and a range of oleochemical products. In this study, different combinations ofCnFATB3,CnLPAAT-BandCnKASIfrom coconut (Cocos nuciferaL.) were coexpressed in transgenicArabidopsis thaliana bya Cre/LoxP multigene expression system. Transgenic lines expressing different combinations of these genes were designated FL (FatB3 + LPAAT-B), FK (FatB3 + KASI) and FLK (FatB3 + LPAAT-B + KASI). The homozygous seeds of transgenicArabidopsis thalianaexpressing high levels of these genes were screened, and their fatty acid composition and lipid contents were determined. Compared with its content in wild-typeA. thaliana, the lauric acid (C12:0) content was significantly increased by at least 395%, 134% and 124% in FLK, FL and FK seeds, respectively. Meanwhile, the myristic acid (C14:0) content was significantly increased by at least 383%, 106% and 102% in FL, FLK and FK seeds, respectively, compared to its level in wild-type seeds. Therefore, the FLK plants exhibited the best effects to increase the level of C12:0, and FL expressed the optimal combination of genes to increase the level of 14:0 MCFA.