Heterologous Reconstitution of Omega-3 Polyunsaturated Fatty Acids inArabidopsis

Reconstitution of nonnative, very-long-chain polyunsaturated fatty acid (VLC-PUFA) biosynthetic pathways inArabidopsis thalianawas undertaken. The introduction of three primary biosynthetic activities to cells requires the stable coexpression of multiple proteins within the same cell. Herein, we report that C₂₂VLC-PUFAs were synthesized from C₁₈precursors by reactions catalyzed byΔ6-desaturase, an ELOVL5-like enzyme involved in VLC-PUFA elongation, andΔ5-desaturase. Coexpression of the corresponding genes (McD6DES, AsELOVL5, andPtD5DES) under the control of the seed-specific vicilin promoter resulted in production of docosapentaenoic acid (22:5 n-3) and docosatetraenoic acid (22:4 n-6) as well as eicosapentaenoic acid (20:5 n-3) and arachidonic acid (20:4 n-6) inArabidopsisseeds. The contributions of the transgenic enzymes and endogenous fatty acid metabolism were determined. Specifically, the reasonable synthesis of omega-3 stearidonic acid (18:4 n-3) could be a useful tool to obtain a sustainable system for the production of omega-3 fatty acids in seeds of a transgenic T3 line 63-1. The results indicated that coexpression of the three proteins was stable. Therefore, this study suggests that metabolic engineering of oilseed crops to produce VLC-PUFAs is feasible.