This is an interesting article from New Scientist about some companies that are working on producing EPA, DHA, and STA in plants:
US FDA says omega-3 oils from GM soya are safe to eat
Excerpt:
“BASF has inserted five genes from algae that naturally make EPA and DHA into the canola genome. Its product is still in development.
“Monsanto has taken a different approach. It inserted two genes into the soybean genome, one from a plant related to primrose and one from a fungus. The modified soybean produces stearidonic acid, or SDA. Like ALA, SDA is converted into EPA in the body, but in much higher proportions….”