Production of Omega-3 Fatty Acids in Plants by Metabolic Engineering
Jong-Bum Kim1*, Kyung-Hee Roh1, Han-Cheol Kang1, Hyun Uk Kim1, Kyeong-Ryeol Lee1, Sun-Hee Kim1, Eun-Young Lee1, Jung-Bong Kim1, Kwang-Soo Kim2
1 National Academy of Agricultural Science, Rural Development Administration, 2National Institute of Crop Science, Rural Development Administration

Omega-3 fatty acids are very healthful in human body, which play roles in the prevention and treatment of cardiovascular disease, atherosclerosis, platelet aggregation and cardiac arrhythmias. α-Linolenic acid(C18:3, ω-3) alone is produced in some plant like perilla and flax seeds,  typical ω-3 fatty acids, such as STA, ETA, EPA, DHA, etc., are biosynthesized in fishes and microorganisms. This is more effective for human health than that. So we have tried to develop the transgenic plants producing ω-3 fatty acid like fish oil by metabolic engineering. First of all, the three genes related to the ω-3 fatty acids biosynthesis were isolated: delta-6 desaturase(McD6DES1) from Muraenesox cinereus, fatty acid elongase (AsELOV5) from Acanthopagrus schlegelii and delta-5 desaturase (PtD5DES) from Phaeodactylum tricornutum. Multiple gene cassette harboring each genes with methanol inducible promoter were constructed, and its leading the production of various polyunsaturated fatty acids in Saccharomyces cerevicea was confirmed. For plant, each gene cassettes were constructed using vicillin promoter and ocs terminator, then each cassettes were cloned into pCAMBIA3300, introduced into Agrobacterium EHA105, then applied to Arabidopsis and rapeseed transformation. The co-expression of the genes (McD6DES1, AsELOV5 and PtD5DES) under control of the seed-specific vicilin promoter resulted in production of stearidonic acid (C18:4, ω-3), docosatetraenoic acid(C22:4, ω-3), docosapentaenoic acid (C22:5, ω-3), eicosapentaenoic acid (C20:5, ω-3),  arachidonic acid (C20:4, ω-6), etc.. The results suggest that ω-3 fatty acids like fish oil should be produced in oilseed crops by metabolic engineering. In the future, we will try to increase ω-3 fatty acids in oil seeds.