Evaluating novel plant oilseeds enriched in omega-3 long-chain polyunsaturated fatty acids to support sustainable development of aquaculture

The widely recognised, highly beneficial effects of fish as components of a healthy diet are almost exclusively derived from their high content of long-chain omega-3 polyunsaturated fatty acids, EPA and DHA, which are known to be essential for proper neural development, and protective against several inflammatory conditions including cardiovascular diseases and some neurological disorders. However, over-exploitation of wild fisheries has meant that an ever-increasing proportion of fish in the human food basket is now farmed. Atlantic salmon, a so-called 'oily fish' and arguably the best source of essential omega-3 fatty acids, are the major farmed fish species in the UK. Paradoxically, diets for farmed carnivorous fish, including salmon, have traditionally been based on fishmeal and fish oil, themselves derived from marine fisheries. Continued development of aquaculture requires feeds to move from these finite, limited and dwindling marine resources to environmentally friendly and ecologically sustainable ingredients, specifically plant meals and vegetable oils, derived from terrestrial agriculture. However, the oil components of plant-based feeds differ substantially from those of marine-based feeds, completely lacking the long-chain omega-3 fatty acids, which has important consequences not only for health of fish, but also the health of human consumers. Therefore, the challenge for aquaculture is how to farm fish in a sustainable and environmentally friendly manner and yet maintain the high levels of long-chain omega-3 fatty acids that confer their nutritional quality and status as beneficial and healthy components of the human diet. The aim of this project is to produce novel vegetable oils specifically enhanced to fit the needs of the aquafeed industry by containing high levels of long-chain omega-3 fatty acids, EPA and DHA, and that can be used to replace our finite reserves of marine fish oil and prevent the over-exploitation of this natural resource. The first goal of the research will be to develop varieties of oilseed plants that can manufacture and accumulate EPA and DHA in their seeds. The oilseed crop of choice, Camelina sativa, also known as false flax or gold-of-pleasure and a relative of rapeseed traditionally grown for oil in Europe, will be modified using a synthetic biology approach that will result in plants metabolically engineered by the inclusion of algal genes to manufacture the long-chain omega-3 fatty acids, EPA and DHA, usually produced only in marine microalgae. The second specific goal will be to formulate plant-based feeds containing the novel, long-chain omega-3 Camelina oils and to test them in feeding trials with Atlantic salmon, which will determine the efficiency, nutritional quality, and safety of the feeds. A third goal will be to study the metabolism of EPA and DHA in fish cells where we can manipulate the fatty acids supplied very precisely and elucidate the biochemical pathways and molecular mechanisms involved in determining the fatty acid composition of cells and, in particular, the conversion of EPA to DHA. These cell studies will inform the metabolic engineering experiments by providing data on the levels and ratios of EPA and DHA required in the novel oils for optimal performance in aquafeed formulations. Since farmed salmon are a major source of long-chain omega-3 in the UK diet, with more than 1.2 million salmon meals eaten per day, this project can make a significant contribution to the health and well-being of the human population in the UK. In addition, by improving the sustainability of the UK fish farming industry, this project will help to protect more than 6000 directly employed and industry-associated jobs in largely rural areas.

The aim of this proposal is to generate a transgenic oilseed (Camelina sativa) possessing the novel trait for the biosynthesis of omega-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFA), eicosapentaenoate (EPA) and docosahexaenoate (DHA), and to evaluate the oils in feeds for Atlantic salmon. Levels of essential n-3 LC-PUFA are critically low in Western diets contributing to high prevalence of many diseases. Fish, particularly farmed fish like salmon, are the major source of n-3 LC-PUFA for humans, but the levels are dependent upon the use of marine fish oil in feeds and so aquaculture represents a non-sustainable production system. The pressure for more sustainable feeds based on plant meals and oils will reduce n-3 LC-PUFA levels in farmed fish. This project proposes to use transgenesis to deliver a designer oilseed that is focussed on the requirements of the aquaculture industry. Transgenic Camelina will be transformed with algal genes encoding the n-3 biosynthetic pathway and expression restricted to the seeds via seed-specific promoters. Transgenic oils will be used in plant-based feeds fed to salmon to evaluate their nutritional quality and safety. Growth performance, feed efficiency and fish health will be determined along with nutrient and fatty acid composition and metabolic/molecular consequences including expression of key target genes. Biochemical and molecular studies in cell cultures will provide data to inform the genetic engineering studies of levels of EPA and DHA required for optimal performance in aquafeeds. Major outcomes will be the development of a GM crop with a high value trait, data to facilitate uptake of this product by the aquaculture industry, an expanded understanding of the basic science underpinning fatty acid nutrition critical to modern fish farming, and key information relevant to feed formulation to maintain nutritional quality of farmed fish and improve competitiveness and sustainability of UK aquaculture.

The outcomes of this project have immense potential to have a major social, economic and health impacts. The project is specifically developed to solve a major problem, fish oil replacement, currently experienced by the fish farming industry globally and is thus essential to the viability, sustainability and competitiveness of UK feed and aquaculture industries. Thus, the overarching goal is the development of a transgenic oilseed (Camelina sativa) specifically focussed on the end-user requirements of the aquafeed industry, which would be provided with a sustainable source of n-3 LC-PUFA, EPA and DHA, allowing for a more integrated approach to the supply chain underpinning this industry. The project is focussed on salmon but, due to the similarity with rainbow trout, it will benefit both the main UK finfish farming sectors. The UK is the world's second largest salmon producer with ex-farm value of £400 million, worldwide retail value of over £1 billion, and contributes over £500 million to the UK economy. Salmon comprises 40% of Scottish food exports, a 500% increase in the last 20 years, and was exported to 59 countries in 2008. Most importantly, fish farming supports employment for over 6,000 people in rural areas in which jobs otherwise are few, and injects £5m every week into these communities as wages and local expenditure. Thus, the primary economic beneficiary will be the UK aquaculture industry through the replacement of marine fish oil with a sustainable home-grown alternative. However, the project could also directly benefit the competitiveness of UK arable agriculture. Although this project is dependent on GM plant technology, which has a limited (but hopefully increasing), role in European agriculture, the opportunities and markets described for aquaculture are global. Aquaculture as a global industry already widely uses GM plant protein in feed formulations for farmed fish. Given this fact, and the imminent industrialisation of fish-farming in China (the world's number one aquaculture producer), the potential for global uptake of n-3 LC-PUFA-rich oils from GM oilseed crops is immense (currently around 2 million tonnes and increasing at 9 % per annum). The project will also contribute to UK policies for sustainability and security of food production, whilst ensuring health and well-being of the UK population. Currently, feed for the aquaculture industry is dependent on the supply of marine oils derived from wild stocks of feed-grade pelagic fisheries. Increasing these fisheries is environmentally unsustainable, and global competition is driving prices to economically non-viable levels. The vast majority of fish oil is produced abroad and the proposed solution, to substitute fish oils with oils from sustainable, home-grown GM oilseeds in aquaculture feeds, addresses sustainability, food security and health issues. Our diet in the UK is recognized as one of the worst in the world. A major factor in this is the very high n-6:n-3 PUFA ratio in our diet, currently averaging around 15:1, which contrasts starkly with the recommended values of 8:1 (EU and US Food Agencies) and 2.5:1 (ISSFAL, International Society for the Study of Fatty Acids and Lipids). N-3 LC-PUFA are particularly effective in redressing this imbalance. The Joint Health Claims Initiative (JHCI) approved generic claim is that 'Eating 3g weekly, 0.45g daily, long chain omega-3 polyunsaturated fatty acids as part of a healthy lifestyle, helps maintain a healthy heart'. The public now know that fish is a prime source of omega-3. It is therefore essential that this situation is not compromised and that, irrespective of the essential changes that must be made in aquaculture feeds, the n-3 LC-PUFA content of farmed fish is maintained. In the present project, consumer health and well-being is paramount, and so maintaining n-3 LC-PUFA content and the nutritional quality of farmed fish is the central and key aim.