Making fish oils in plants: from alpha to omega.

The transgenic accumulation of omega-3 long-chain polyunsaturated fatty acids represents one of the most complex assemblies of heterologous sequences in a plant host. Through the combined efforts of multiple research teams from public and private sectors, GM crops synthesising these important fatty acids have progressed from the initial proof-of-principle stage to fully regulated and approved products. That this has taken over 25 years should not be surprising, but equally, there are several aspects of the sophisticated metabolic engineering which remain unresolved. The aim of this short review is to shine a light on some of the less familiar aspects of these efforts and to maybe prompt renewed consideration of the associated issues. In particular, the oft-ignored topic of transgene silencing in plant biotechnology is considered, as is the potential of multicistronic polyprotein fusions to reduce construct complexity and sequence repetition. Collectively, it is hoped that focussing on these important but neglected topics will inspire a new wave of research activity, underpinning a further shift to a fully sustainable bioeconomy.