Transgenic Oilseed Crop Camelina sativa as an Alternative to Fish Oils
Olga Sayanova, Noemi Ruiz- Lopez, Richard P. Haslam, Sarah L. Usher, 
Johnathan A. Napier
Rothamsted Research, Harpenden, U.K

It is now well established that omega-3 long chain polyunsaturated fatty acids (LC-PUFAs), especially  eicosapentaenoic acid (EPA; 20:5∆5,8,11,14,17) and docosahexaenoic acid (DHA; 22:6∆4,7,10,13,16,19) are essential constituents of human nutrition and have key roles in growth  and development  of infants and children and in maintaining health through their effects on immune system. There is growing evidence from clinical studies that the presence of omega-3 LC-PUFAs in the human diet has therapeutic effect in conditions such as cardiovascular diseases, obesity, metabolic syndrome and eczema. Although marine fish is the current main dietary source of EPA and DHA, the depletion of wild fish stocks and pollution of the marine environment indicate an urgent need for an alternative and sustainable source of omega-3 LC-PUFAs. The engineering of  plants  to synthesize high levels of  EPA and DHA would be the  most promising and cost-effective solution for large-scale production of LC-PUFAs.  
A variety of strategies have been used to express the LC-PUFAs metabolic pathways in oil crops, utilizing desaturases and elongases genes involved in different biosynthetic routes for EPA and DHA accumulation. We used a stepwise metabolic engineering approach to optimize levels of LC-PUFAs in transgenic oilseeds. In order to investigate the impact of different genes and promoters on accumulation of LC-PUFAs a series of transformation with variable numbers of transgenes have been performed. The efficient reconstitution of LC-PUFA biosynthesis in transgenic plants has been demonstrated. Our studies have identified an optimal set of genes with which to successfully direct the transgenic synthesis of EPA or DHA in the seed oil of the crop Camelina sativa.