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      High level accumulation of EPA and DHA in field‐grown transgenic Camelina – a multi‐territory evaluation of TAG accumulation and heterogeneity

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          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.

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          Most cited references 44

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          Successful high-level accumulation of fish oil omega-3 long-chain polyunsaturated fatty acids in a transgenic oilseed crop

          Omega-3 (also called n-3) long-chain polyunsaturated fatty acids (≥C20; LC-PUFAs) are of considerable interest, based on clear evidence of dietary health benefits and the concurrent decline of global sources (fish oils). Generating alternative transgenic plant sources of omega-3 LC-PUFAs, i.e. eicosapentaenoic acid (20:5 n-3, EPA) and docosahexaenoic acid (22:6 n-3, DHA) has previously proved problematic. Here we describe a set of heterologous genes capable of efficiently directing synthesis of these fatty acids in the seed oil of the crop Camelina sativa, while simultaneously avoiding accumulation of undesirable intermediate fatty acids. We describe two iterations: RRes_EPA in which seeds contain EPA levels of up to 31% (mean 24%), and RRes_DHA, in which seeds accumulate up to 12% EPA and 14% DHA (mean 11% EPA and 8% DHA). These omega-3 LC-PUFA levels are equivalent to those in fish oils, and represent a sustainable, terrestrial source of these fatty acids. We also describe the distribution of these non-native fatty acids within C. sativa seed lipids, and consider these data in the context of our current understanding of acyl exchange during seed oil synthesis.
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            Omega-3 Long-Chain Polyunsaturated Fatty Acids, EPA and DHA: Bridging the Gap between Supply and Demand

            The omega-3 (n-3) long-chain polyunsaturated fatty acids (LC-PUFA), eicosapentaenoic (EPA, 20:5n-3) and docosahexaenoic (DHA, 22:6n-3) acids, are well accepted as being essential components of a healthy, balanced diet, having beneficial effects on development and in mitigating a range of pathological conditions. However, their global supply from all the traditional sources of these nutrients is insufficient to satisfy human nutritional requirements. For two decades there has been considerable research carried out into all possible alternatives to the main sources of n-3 LC-PUFA, marine fish oil and fishmeal, driven largely by the aquaculture sector, as both the major user and provider of EPA and DHA. In the last few years these efforts have focused increasingly on the development of entirely new supplies of n-3 LC-PUFA produced de novo. Recently, this has resulted in various new sources of EPA and/or DHA that are already available or likely to available in the near future. In this short review, we briefly summaries the current gap between supply and demand of EPA and DHA for human requirements, the role of aquaculture in providing n-3 LC-PUFA to human consumers, the range of potential novel sources, and suggest how these new products could be used effectively. We conclude that all the new sources have potentially important roles to play in increasing the supply of n-3 LC-PUFA so that they are available more widely and in higher concentrations providing more options and opportunities for human consumers to obtain sufficient EPA and DHA to support more healthy, balanced diets.
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              Metabolic Engineering Plant Seeds with Fish Oil-Like Levels of DHA

              Background Omega-3 long-chain (≥C20) polyunsaturated fatty acids (ω3 LC-PUFA) have critical roles in human health and development with studies indicating that deficiencies in these fatty acids can increase the risk or severity of cardiovascular and inflammatory diseases in particular. These fatty acids are predominantly sourced from fish and algal oils, but it is widely recognised that there is an urgent need for an alternative and sustainable source of EPA and DHA. Since the earliest demonstrations of ω3 LC-PUFA engineering there has been good progress in engineering the C20 EPA with seed fatty acid levels similar to that observed in bulk fish oil (∼18%), although undesirable ω6 PUFA levels have also remained high. Methodology/Principal Findings The transgenic seed production of the particularly important C22 DHA has been problematic with many attempts resulting in the accumulation of EPA/DPA, but only a few percent of DHA. This study describes the production of up to 15% of the C22 fatty acid DHA in Arabidopsis thaliana seed oil with a high ω3/ω6 ratio. This was achieved using a transgenic pathway to increase the C18 ALA which was then converted to DHA by a microalgal Δ6-desaturase pathway. Conclusions/Significance The amount of DHA described in this study exceeds the 12% level at which DHA is generally found in bulk fish oil. This is a breakthrough in the development of sustainable alternative sources of DHA as this technology should be applicable in oilseed crops. One hectare of a Brassica napus crop containing 12% DHA in seed oil would produce as much DHA as approximately 10,000 fish.
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                Author and article information

                Contributors
                johnathan.napier@rothamsted.ac.uk
                Journal
                Plant Biotechnol J
                Plant Biotechnol J
                10.1111/(ISSN)1467-7652
                PBI
                Plant Biotechnology Journal
                John Wiley and Sons Inc. (Hoboken )
                1467-7644
                1467-7652
                08 May 2020
                November 2020
                : 18
                : 11 ( doiID: 10.1111/pbi.v18.11 )
                : 2280-2291
                Affiliations
                [ 1 ] Department of Plant Sciences Rothamsted Research Harpenden Herts UK
                [ 2 ]Present address: Department of Plant Breeding Swedish University of Agricultural Sciences Alnarp Sweden
                Author notes
                [* ] Correspondence (Tel +44 1582 938136; e‐mail: johnathan.napier@ 123456rothamsted.ac.uk )

                Article
                PBI13385
                10.1111/pbi.13385
                7589388
                32304615
                © 2020 The Authors. Plant Biotechnology Journal published by Society for Experimental Biology and The Association of Applied Biologists and John Wiley & Sons Ltd

                This is an open access article under the terms of the http://creativecommons.org/licenses/by/4.0/ License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

                Page count
                Figures: 6, Tables: 0, Pages: 12, Words: 10028
                Product
                Funding
                Funded by: Biotechnology and Biological Sciences Research Council , open-funder-registry 10.13039/501100000268;
                Award ID: BBS/E/C/00005207
                Award ID: BBS/E/C/000I0420
                Categories
                Research Article
                Research Articles
                Custom metadata
                2.0
                November 2020
                Converter:WILEY_ML3GV2_TO_JATSPMC version:5.9.3 mode:remove_FC converted:27.10.2020

                Biotechnology

                omega‐3, camelina, metabolic engineering, gm field trials

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