Molecular cloning and characterization of long-chain acyl-CoA synthetase 9 from the mesocarp of African oil palm (Elaeis guineensis Jacq.)

The oil palm (Elaeis guineensis Jacq.) is the prime source of vegetable oil for many tropical countries for its extremely high oil content in fruit. In previous researches, LACS9 has been proved that it plays an important role in plant cells by regulating lipid metabolic pathways. However, its function in oil palm has not yet been fully elucidated. In this paper, a full-length cDNA encoding EgLACS9 was cloned from the mesocarp of oil palm, and subcellular localization confirmed that it was located in the endoplasmic reticulum (ER). Meanwhile, overexpression of EgLACS9 in the LACS-deficient S. cerevisiae strain YB525 indicated that EgLACS9 can rescue the deficiency of LACS gene and take up activating exogenous fatty acids. Especially, three kinds of fatty acid, including C16:0, C18:0 and C18:1, displayed a significant decrease in EgLACS9-overexpressing cells. Moreover, EgLACS9 was also overexpressed in embryoids induced from oil palm. In three obtained transgenic embryoid lines, the content of long-chain fatty acids (including C20:1, C20:2 and C24:0) was increased substantially. Meanwhile, the levels of C18:1 and C18:2 were significantly reduced. Together, these results fully elucidated the function of EgLACS9 in regulation of fatty acids accumulation in oil palm.