Production of Very Long Chain Polyunsaturated Fatty Acids in Cotton

We have isolated four genes encoding a Δ9 elongase, a Δ8 desaturase, a Δ5 desaturase, and a Δ15 desaturase from Isochrysis galbana, Euglena gracilis, Mortierella alpina, and Arabidopsis thaliana respectively.Using a multigene transfer technology that we developed, these genes were stacked together in the plant expression vector pCambia2300.Each gene contained its own CaMV35S promoter and Tnos terminator.This plant expression vector was then transferred into cotton by Agrobacterium-mediated transformation method.Transgenic cotton seedlings were first identified by screening them based on kanamycin-containing media and followed by PCR with gene-specific primers of the four transgenes.Finally, these transgenic plants were subjected to gas liquid chromatography analysis for their fatty acid composition and the results showed that the contents of arachidonic acid (ARA, 20:4Δ 5,8,11,14 ) and eicosapentaenoic acid (EPA, 20:5Δ 5,8,11,14,17 ) were 1.0% and 5.0% respectively in the leaves of the transgenic plants, indicating that the four genes were expressed in cotton.Therefore, our data clearly demonstrated the feasibility for the heterologous production of EPA in cotton and this will lay a foundation for the production of VLCPUFAs, including EPA and DHA in cotton seed through transgenic technology in the future.