Expression of Δ6, Δ5 desaturase and GLELO elongase genes from Mortierella alpina for production of arachidonic acid in soybean [Glycine max (L.) Merrill] seeds

We report the production of arachidonic acid (ARA) in seeds of soybean [Glycine max (L.) Merrill] by seed-specific expression of the genes encoding Δ6 desaturase, fatty acid elongase, and Δ5 desaturase from a filamentous fungus, Mortierella alpina 1S-4, as well as the down-regulation of an endogenous gene of soybean, Δ15 desaturase. Several fatty acids, γ-linolenic acid (GLA), eicosa-8, 11-dienoic acid (EDA), dihomo-γ-linolenic acid (DGLA), and ARA, which the host plant does not produce, accumulated up to 11.0 and 8.4% of the total fatty acids in the transgenic histodifferentiated somatic embryos and the transgenic mature seeds, respectively. The ability to synthesize these novel fatty acids was inherited to their progenies. These results indicate that metabolic engineering of the fatty acid biosynthetic pathway to produce desired very long-chain polyunsaturated fatty acids in oilseed crops is feasible.