Identification of a Δ12 fatty acid desaturase from oil palm (Elaeis guineensis Jacq.) involved in the biosynthesis of linoleic acid by heterologous expression in Saccharomyces cerevisiae

• A Δ12-desaturases associated with LC-PUFA biosynthesis were cloned from oil palm (Elaeis guineensis Jacq).
• The yield of egFAD2 was the highest in the mesocarp of oil palm fruits at 120-140 DAP.
• Heterologous expression of egFAD2 in Saccharomyces cerevisiae produced an appreciable amount of linoleic acids.
• These results indicated that the egFAD2 was able to converted oleic acid to linoleic acid but did not accept palmitoleic acid as a substrate.

Oil palm (Elaeis guineensis Jacq.) is one of the highest oil-yield crops in the world. A Δ12-desaturases associated with the primary steps of long-chain polyunsaturated fatty acid (LC-PUFA) biosynthesis were successfully cloned from oil palm and their functions identified. The open reading frames (ORFs) of egFAD2 (GenBank accession: KT023602) consisted of 1176 bp and code for 391 amino acids. Their deduced polypeptides showed 75–93% identity to microsomal Δ12-desaturases from other higher plants, and each contained the three histidine clusters typical of the catalytic domains of such enzymes. RT-PCR experiment indicated that the egFAD2 gene exhibited the highest accumulation in the mesocarp of fruits at 120–140 DAP (i.e. the fourth period of fruit development) and, despite having different expression levels, the other four stages were at significantly lower levels compared with the fourth stage. Plasmid pYES2-egFAD2 was transformed into Saccharomyces cerevisiae strain INVSc1 using lithium acetate method for expression under the induction of galactose. Yeast cells transformed with plasmid constructs containing egFAD12 produced an appreciable amount of linoleic acids (18:2Δ9,12), not normally present in wild-type yeast cells, indicating that the genes encoded functional Δ12-desaturase enzymes.