Abstract
The transgene‐directed accumulation of non‐native omega‐3 long chain polyunsaturated fatty acids in the seed oil of Camelina sativa (Camelina) was evaluated in the field, in distinct geographical and regulatory locations. A construct, DHA2015.1, containing an optimal combination of biosynthetic genes, was selected for experimental field release in the UK, USA and Canada, and the accumulation of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) determined. The occurrence of these fatty acids in different triacylglycerol species was monitored and found to follow a broad trend irrespective of the agricultural environment. This is a clear demonstration of the stability and robust nature of the transgenic trait for omega‐3 long chain polyunsaturated fatty acids in Camelina. Examination of non‐seed tissues for the unintended accumulation of EPA and DHA failed to identify their presence in leaf, stem, flower, anther or capsule shell material, confirming the seed‐specific accumulation of these novel fatty acids. Collectively, these data confirm the promise of GM plant‐based sources of so‐called omega‐3 fish oils as a sustainable replacement for oceanically derived oils.
Highlights
There is continued interest in the sustainable production of omega-3 long chain polyunsaturated fatty acids (LC-PUFAs), known as omega-3 fish oils, based on their central importance in marine aquaculture and human health and nutrition (Tocher et al, 2019)
In an effort to further improve our constructs through systematic iteration, efforts were undertaken to identify superior examples of the gene encoding the last step in the omega-3 LC-PUFA biosynthetic pathway (D4-desaturase; see Figure 1), since previous studies in Arabidopsis had indicated a role for this enzyme in determining flux through the heterologous pathway and onwards into TAG (Ruiz-Lopez et al, 2013)
We only made a single modification to our construct, this had a pronounced effect on the total seed fatty acid composition and to a lesser extent, the seed TAG profile (Usher et al, 2017)
Summary
There is continued interest in the sustainable production of omega-3 long chain polyunsaturated fatty acids (LC-PUFAs), known as omega-3 fish oils, based on their central importance in marine aquaculture and human health and nutrition (Tocher et al, 2019). One approach, which has successfully gone from theoretical concept to commercial prototyping, is the use of transgenic plants to accumulate these valuable fatty acids in their seed oil (Napier et al, 2018; 2019) In such a scenario, genetic modification (GM) is used to introduce the non-native biosynthetic pathway for omega-3 LC-PUFAs into the nuclear genome of a suitable oilseed host, enabling the plant to convert endogenous C18 fatty acids into the more desirable C20 + LCPUFAs such as eicosapentaenoic acid (EPA; 20:5D5,8,11,14,17) and docosahexaenoic acid (DHA; 22:6D4,7,10,13,16,19) (Napier et al, 2018). Some fundamental questions remain regarding the accumulation and compartmentation of EPA and DHA in seed storage lipid
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