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

Inclusion of oil from transgenic Camelina sativa in feed effectively supplies EPA and DHA to Atlantic salmon (Salmo salar) grown to market size in seawater pens

Atlantic salmon were fed either a diet reflecting current commercial feeds with added oil supplied by a blend of fish oil and rapeseed oil (COM), or a diet formulated with oil from transgenic Camelina sativa containing 20% EPA + DHA (TCO). Salmon were grown from smolt to market size (>3 kg) in sea pens under semi-commercial conditions. There were no differences in growth, feed efficiency or survival between fish fed the TCO or COM diets at the end of the trial. Levels of EPA + DHA in flesh of salmon fed TCO were significantly higher than in fish fed COM. A 140 g fillet from TCO-fed salmon delivered 2.3 g of EPA + DHA, 67% of the weekly requirement level recommended by many health agencies, and 1.5-fold more than the 1.5 g of EPA + DHA for COM-fed fish. Oil from transgenic Camelina supported growth and improved the nutritional quality of farmed salmon in terms of increased "omega-3" supply for human consumers.

Comparative study for metabolomics, antioxidant activity, and molecular docking simulation of the newly bred Korean red rice accessions

This study analyzed the metabolite profiles and antioxidant capacities of two waxy and non-waxy Korean red rice accessions newly bred. Fifteen phenolic compounds were detected in the rice samples. Accession1 had high fatty acids, phytosterols, and vitamin E; accession3 had high vitamin E and phytosterol; and accession4 had a high total flavonoid. The correlation analysis findings from this study validated the positive association between all the metabolites and antioxidant activity. in silico results revealed that protocatechuic acid had a docking score of -9.541, followed by luteolin, quercetin, and caffeic acid, all of which had significant docking scores and a significant number of contacts. Similarly, molecular dynamics simulations showed that phytochemicals had root mean square deviation values of <2.8 Å with Keap 1, indicating better stability. This study provides valuable insights into potential directions for future investigations and improvements in the functional qualities of other colored rice varieties.

Metabolic engineering of omega-3 long chain polyunsaturated fatty acids in plants using different ∆6- and ∆5-desaturases co-expressed with LPCAT from the marine diatom Phaeodactylum tricornutum

Continuous research on obtaining an even more efficient production of very long-chain polyunsaturated fatty acids (VLC-PUFAs) in plants remains one of the main challenges of scientists working on plant lipids. Since crops are not able to produce these fatty acids due to the lack of necessary enzymes, genes encoding them must be introduced exogenously from native organisms producing VLC-PUFAs. In this study we reported, in tobacco leaves, the characterization of three distinct ∆6-desaturases from diatom Phaeodactylum tricornutum, fungi Rhizopus stolonifer and microalge Osterococcus tauri and two different ∆5-desaturases from P. tricornutum and single-celled saprotrophic eukaryotes Thraustochytrium sp. The in planta agroinfiltration of essential ∆6-desaturases, ∆6-elongases and ∆5-desaturases allowed for successful introduction of eicosapentaenoic acid (20:5∆5,8,11,14,17) biosynthesis pathway. However, despite the desired, targeted production of ω3-fatty acids we detected the presence of ω6-fatty acids, indicating and confirming previous results that all tested desaturases are not specifically restricted to neither ω3- nor ω6-pathway. Nevertheless, the additional co-expression of acyl-CoA:lysophosphatidylcholine acyltransferase (LPCAT) from Phaeodactylum tricornutum boosted the proportion of ω3-fatty acids in newly synthesized fatty acid pools. For the most promising genes combinations the EPA content reached at maximum 1.4% of total lipid content and 4.5% of all fatty acids accumulated in the TAG pool. Our results for the first time describe the role of LPCAT enzyme and its effectiveness in alleviating a bottleneck called 'substrate dichotomy' for improving the transgenic production of VLC-PUFAs in plants.

Biochemical characterization of acyl-CoA:diacylglycerol acyltransferase2 from the diatom Phaeodactylum tricornutum and its potential effect on LC-PUFAs biosynthesis in planta

BACKGROUND

Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), belonging to ω-3 long-chain polyunsaturated fatty acids (ω3-LC-PUFAs), are essential components of human diet. They are mainly supplemented by marine fish consumption, although their native producers are oleaginous microalgae. Currently, increasing demand for fish oils is insufficient to meet the entire global needs, which puts pressure on searching for the alternative solutions. One possibility may be metabolic engineering of plants with an introduced enzymatic pathway producing ω3-LC-PUFAs.

RESULT

In this study we focused on the acyl-CoA:diacylglycerol acyltransferase2b (PtDGAT2b) from the diatom Phaeodactylum tricornutum, an enzyme responsible for triacylglycerol (TAG) biosynthesis via acyl-CoA-dependent pathway. Gene encoding PtDGAT2b, incorporated into TAG-deficient yeast strain H1246, was used to confirm its activity and conduct biochemical characterization. PtDGAT2b exhibited a broad acyl-CoA preference with both di-16:0-DAG and di-18:1-DAG, whereas di-18:1-DAG was favored. The highest preference for acyl donors was observed for 16:1-, 10:0- and 12:0-CoA. PtDGAT2b also very efficiently utilized CoA-conjugated ω-3 LC-PUFAs (stearidonic acid, eicosatetraenoic acid and EPA). Additionally, verification of the potential role of PtDGAT2b in planta, through its transient expression in tobacco leaves, indicated increased TAG production with its relative amount increasing to 8%. Its co-expression with the gene combinations aimed at EPA biosynthesis led to, beside elevated TAG accumulation, efficient accumulation of EPA which constituted even 25.1% of synthesized non-native fatty acids (9.2% of all fatty acids in TAG pool).

CONCLUSIONS

This set of experiments provides a comprehensive biochemical characterization of DGAT enzyme from marine microalgae. Additionally, this study elucidates that PtDGAT2b can be used successfully in metabolic engineering of plants designed to obtain a boosted TAG level, enriched not only in ω-3 LC-PUFAs but also in medium-chain and ω-7 fatty acids.

Conjugated Microporous Polymers for Catalytic CO2 Conversion

Rising carbon dioxide (CO2) levels in the atmosphere are recognized as a threat to atmospheric stability and life. Although this greenhouse gas is being produced on a large scale, there are solutions to reduction and indeed utilization of the gas. Many of these solutions involve costly or unstable technologies, such as air-sensitive metal-organic frameworks (MOFs) for CO2 capture or "non-green" systems such as amine scrubbing. Conjugated microporous polymers (CMPs) represent a simpler, cheaper, and greener solution to CO2 capture and utilization. They are often easy to synthesize at scale (a one pot reaction in many cases), chemically and thermally stable (especially in comparison with their MOF and covalent organic framework (COF) counterparts, owing to their amorphous nature), and, as a result, cheap to manufacture. Furthermore, their large surface areas, tunable porous frameworks and chemical structures mean they are reported as highly efficient CO2 capture motifs. In addition, they provide a dual pathway to utilize captured CO2 via chemical conversion or electrochemical reduction into industrially valuable products. Recent studies show that all these attractive properties can be realized in metal-free CMPs, presenting a truly green option. The promising results in these two fields of CMP applications are reviewed and explored here.

Alternative sources of bioactive omega-3 fatty acids: what are the options?

PURPOSE OF REVIEW

The very-long chain (VLC) omega-3 polyunsaturated fatty acids (PUFAs) eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) promote optimal development, physiological function and healthy ageing and help to manage disease. EPA and DHA are sourced mainly from fish, which is not sustainable. This review explores alternative sustainable sources.

RECENT FINDINGS

Recent research confirms that higher intake and status of EPA and DHA are associated with health benefits including lower risk of incident type-2 diabetes and cardiovascular disease mortality. Meta-analyses confirm benefits of intravenous EPA and DHA in hospitalized adults. Algal oils and seed oils from some genetically modified (GM) plants are sources of EPA and DHA. An oil from GM camelina showed equivalence with fish oil in human trials. Ahiflower oil, a source of stearidonic acid, had biological effects in experimental studies that might translate into health benefits. An intravenous lipid emulsion based on Ahiflower oil has been tested in experimental research. Pine nut oil (PNO) is a source of pinolenic acid, which is not an omega-3 PUFA but has similar actions.

SUMMARY

Algal oils, oils from GM seed crops, Ahiflower oil and other sources of stearidonic acid, and nonomega-3 oils including PNO, are plant-sourced sustainable alternatives to fish-sourced VLC omega-3 PUFAs.

Biotechnological production of omega-3 fatty acids: current status and future perspectives

Omega-3 fatty acids, including alpha-linolenic acids (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA), have shown major health benefits, but the human body's inability to synthesize them has led to the necessity of dietary intake of the products. The omega-3 fatty acid market has grown significantly, with a global market from an estimated USD 2.10 billion in 2020 to a predicted nearly USD 3.61 billion in 2028. However, obtaining a sufficient supply of high-quality and stable omega-3 fatty acids can be challenging. Currently, fish oil serves as the primary source of omega-3 fatty acids in the market, but it has several drawbacks, including high cost, inconsistent product quality, and major uncertainties in its sustainability and ecological impact. Other significant sources of omega-3 fatty acids include plants and microalgae fermentation, but they face similar challenges in reducing manufacturing costs and improving product quality and sustainability. With the advances in synthetic biology, biotechnological production of omega-3 fatty acids via engineered microbial cell factories still offers the best solution to provide a more stable, sustainable, and affordable source of omega-3 fatty acids by overcoming the major issues associated with conventional sources. This review summarizes the current status, key challenges, and future perspectives for the biotechnological production of major omega-3 fatty acids.

Adapting enzymes to improve their functionality in plants: why and how

Synthetic biology creates new metabolic processes and improves existing ones using engineered or natural enzymes. These enzymes are often sourced from cells that differ from those in the target plant organ with respect to, e.g. redox potential, effector levels, or proteostasis machinery. Non-native enzymes may thus need to be adapted to work well in their new plant context ('plantized') even if their specificity and kinetics in vitro are adequate. Hence there are two distinct ways in which an enzyme destined for use in plants can require improvement: In catalytic properties such as substrate and product specificity, kcat, and KM; and in general compatibility with the milieu of cells that express the enzyme. Continuous directed evolution systems can deliver both types of improvement and are so far the most broadly effective way to deliver the second type. Accordingly, in this review we provide a short account of continuous evolution methods, emphasizing the yeast OrthoRep system because of its suitability for plant applications. We then cover the down-to-earth and increasingly urgent issues of which enzymes and enzyme properties can - or cannot - be improved in theory, and which in practice are the best to target for crop improvement, i.e. those that are realistically improvable and important enough to warrant deploying continuous directed evolution. We take horticultural crops as examples because of the opportunities they present and to sharpen the focus.

A review on the identification of transgenic oilseeds and oils

Transgenic technology can increase the quantity and quality of vegetable oils worldwide. However, people are skeptical about the safety of transgenic oil-bearing crops and the oils they produce. In order to protect consumers' rights and avoid transgenic oils being adulterated or labeled as nontransgenic oils, the transgenic detection technology of oilseeds and oils needs careful consideration. This paper first summarized the current research status of transgenic technologies implemented at oil-bearing crops. Then, an inspection process was proposed to detect a large number of samples to be the subject rapidly, and various inspection strategies for transgenic oilseeds and oils were summarized according to the process sequence. The detection indicators included oil content, fatty acid, triglyceride, tocopherol, and nucleic acid. The detection technologies involved chromatography, spectroscopy, nuclear magnetic resonance, and polymerase chain reaction. It is hoped that this article can provide crucial technical reference and support for staff engaging in the supervision of transgenic food and for researchers developing fast and efficient monitoring methods in the future.

Polyunsaturated Fatty Acids: Conversion to Lipid Mediators, Roles in Inflammatory Diseases and Dietary Sources

Polyunsaturated fatty acids (PUFAs) are important components of the diet of mammals. Their role was first established when the essential fatty acids (EFAs) linoleic acid and α-linolenic acid were discovered nearly a century ago. However, most of the biochemical and physiological actions of PUFAs rely on their conversion to 20C or 22C acids and subsequent metabolism to lipid mediators. As a generalisation, lipid mediators formed from n-6 PUFAs are pro-inflammatory while those from n-3 PUFAs are anti-inflammatory or neutral. Apart from the actions of the classic eicosanoids or docosanoids, many newly discovered compounds are described as Specialised Pro-resolving Mediators (SPMs) which have been proposed to have a role in resolving inflammatory conditions such as infections and preventing them from becoming chronic. In addition, a large group of molecules, termed isoprostanes, can be generated by free radical reactions and these too have powerful properties towards inflammation. The ultimate source of n-3 and n-6 PUFAs are photosynthetic organisms which contain Δ-12 and Δ-15 desaturases, which are almost exclusively absent from animals. Moreover, the EFAs consumed from plant food are in competition with each other for conversion to lipid mediators. Thus, the relative amounts of n-3 and n-6 PUFAs in the diet are important. Furthermore, the conversion of the EFAs to 20C and 22C PUFAs in mammals is rather poor. Thus, there has been much interest recently in the use of algae, many of which make substantial quantities of long-chain PUFAs or in manipulating oil crops to make such acids. This is especially important because fish oils, which are their main source in human diets, are becoming limited. In this review, the metabolic conversion of PUFAs into different lipid mediators is described. Then, the biological roles and molecular mechanisms of such mediators in inflammatory diseases are outlined. Finally, natural sources of PUFAs (including 20 or 22 carbon compounds) are detailed, as well as recent efforts to increase their production.

Physaria fendleri FAD3-1 overexpression increases ɑ-linolenic acid content in Camelina sativa seeds

Camelina (Camelina sativa) is an oil crop with a short growing period, resistance to drought and cold, low fertilizer requirements, and can be transformed using floral dipping. Seeds have a high content of polyunsaturated fatty acids, especially ɑ-linolenic acid (ALA), at 32-38%. ALA is an omega-3 fatty acid that is a substrate for eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in the human body. In this study, ALA content was further enhanced by the seed-specific expression of Physaria fendleri FAD3-1 (PfFAD3-1) in camelina. The ALA content increased up to 48% in T2 seeds and 50% in T3 seeds. Additionally, size of the seeds increased. The expression of fatty acid metabolism-related genes in PfFAD3-1 OE transgenic lines was different from that in the wild type, where the expression of CsFAD2 decreased and CsFAD3 increased. In summary, we developed a high omega-3 fatty acid-containing camelina with up to 50% ALA content by introducing PfFAD3-1. This line can be used for genetic engineering to obtain EPA and DHA from seeds.

Phosphate deficiency modifies lipid composition and seed oil production in camelina

Camelina (Camelina sativa) is an emerging industrial oilseed crop because of its potential for double cropping, fallow year production, growth on marginal lands, and multiple uses of seed oils and meals. To realize the potential for sustainable production of camelina, a better understanding of how camelina seed oil production and composition respond to low input environments is desired. Phosphorus (P) is one of the least available essential macronutrients to plants with finite worldwide supply. This study investigated seed oil production and lipid composition of camelina in field settings and under greenhouse conditions in response to P deficiency. Lipidomic profiling reveals that P deficiency in field settings triggered extensive leaf lipid remodeling that decreased the ratio of phospholipids to non-P-containing galactolipids from 30% to 5% under P sufficient to deficient conditions. P deficiency increased seed oil content per seed weight by approximately 25% and 20% in field and greenhouse settings, respectively. In addition, P deficiency altered seed fatty acid composition, with increases in monounsaturated 18:1 and 20:1 and decreases in polyunsaturated 18:3. Total seed production was decreased by 10- to 15-fold under P deficiency and the decrease resulted from reduced seed numbers without affecting seed weight. The results from field and greenhouse conditions indicate that P deficiency increases seed oil content, alters fatty acid composition, and decreases greatly seed production, suggesting that achieving a high yield and quality of camelina seed oil is positively linked to P status of soil.

Engineering Nutritionally Improved Edible Plant Oils

In contrast to traditional breeding, which relies on the identification of mutants, metabolic engineering provides a new platform to modify the oil composition in oil crops for improved nutrition. By altering endogenous genes involved in the biosynthesis pathways, it is possible to modify edible plant oils to increase the content of desired components or reduce the content of undesirable components. However, introduction of novel nutritional components such as omega-3 long-chain polyunsaturated fatty acids needs transgenic expression of novel genes in crops. Despite formidable challenges, significant progress in engineering nutritionally improved edible plant oils has recently been achieved, with some commercial products now on the market.

Microorganisms in Fish Feeds, Technological Innovations, and Key Strategies for Sustainable Aquaculture

Aquaculture, the world's fastest growing food sector, produces over half of all fish for human consumption. Aquaculture feeds include fishmeal and fish oil, extracted from wild-caught fish such as sardines, and poses ecological, food security, and economic drawbacks. Microalgae, yeasts, fungi, bacteria, and other alternative ingredients show promise as potential ingredients in aquafeeds that provide protein/amino acids, lipids, or omega-3 sources and sources of bioactive molecules. This review article discusses the issues that the literature often lacks data on, such as the recent development of using microorganisms, technological innovation, challenges, and opportunities to develop a low environmental footprint of aquaculture diet. The ingredients often require novel processing technology to improve digestibility and fish growth and reduce antinutritional factors. This is an important gap to fill because microalgae are the most frequently used organism in fish feed, particularly as a dietary supplement or mixed with other ingredients. The production, processing, and formulating steps can affect the nutritional qualities. Stepwise strategies are required to evaluate these ingredients for feed application, and in this article, I articulated the stepwise key approaches of evaluating nutritional and environmental response metrics to develop highly sustainable aquaculture feed using these microorganisms, which would guide a more judicious inclusion of these novel ingredients.

Engineered Cleistogamy in Camelina sativa for bioconfinement

Camelina sativa is a self-pollinating and facultative outcrossing oilseed crop. Genetic engineering has been used to improve camelina yield potential for altered fatty acid composition, modified protein profiles, improved seed and oil yield, and enhanced drought resistance. The deployment of transgenic camelina in the field posits high risks related to the introgression of transgenes into non-transgenic camelina and wild relatives. Thus, effective bioconfinement strategies need to be developed to prevent pollen-mediated gene flow (PMGF) from transgenic camelina. In the present study, we overexpressed the cleistogamy (i.e. floral petal non-openness)-inducing PpJAZ1 gene from peach in transgenic camelina. Transgenic camelina overexpressing PpJAZ1 showed three levels of cleistogamy, affected pollen germination rates after anthesis but not during anthesis, and caused a minor silicle abortion only on the main branches. We also conducted field trials to examine the effects of the overexpressed PpJAZ1 on PMGF in the field, and found that the overexpressed PpJAZ1 dramatically inhibited PMGF from transgenic camelina to non-transgenic camelina under the field conditions. Thus, the engineered cleistogamy using the overexpressed PpJAZ1 is a highly effective bioconfinement strategy to limit PMGF from transgenic camelina, and could be used for bioconfinement in other dicot species.

Engineering plant-based feedstocks for sustainable aquaculture

There is a growing recognition of the challenges associated with ensuring good nutrition for all without compromising the environment. This is particularly true for aquaculture, given the reliance on marine extraction for key feed ingredients, yet at the same time it delivers key nutrients such as omega-3 long chain polyunsaturated fatty acids. This review will consider progress in transitioning away from oceanic-derived fish oils as feed ingredients, focusing on the emerging transgenic plant sources of these fatty acids. Specific consideration is given to the "validation" phase of this process, in which oils from GM plants are used as substitutes for bona fide fish oils in aquafeed diets. Equally, consideration is given to the demonstration of "real-world" potential by GM field trials. Collectively, the status of these new plant-based sources of omega-3 fish oils confirm the arrival of a new wave of plant biotech products, 25 years after the introduction of herbicide-tolerant input traits and demonstrate the power of GM agriculture to contribute to food security and operating within planetary boundaries.

Genetic Improvement of Camelina sativa (L.) Crantz: Opportunities and Challenges

In recent years, a renewed interest in novel crops has been developing due to the environmental issues associated with the sustainability of agricultural practices. In particular, a cover crop, Camelina sativa (L.) Crantz, belonging to the Brassicaceae family, is attracting the scientific community's interest for several desirable features. It is related to the model species Arabidopsis thaliana, and its oil extracted from the seeds can be used either for food and feed, or for industrial uses such as biofuel production. From an agronomic point of view, it can grow in marginal lands with little or no inputs, and is practically resistant to the most important pathogens of Brassicaceae. Although cultivated in the past, particularly in northern Europe and Italy, in the last century, it was abandoned. For this reason, little breeding work has been conducted to improve this plant, also because of the low genetic variability present in this hexaploid species. In this review, we summarize the main works on this crop, focused on genetic improvement with three main objectives: yield, seed oil content and quality, and reduction in glucosinolates content in the seed, which are the main anti-nutritional substances present in camelina. We also report the latest advances in utilising classical plant breeding, transgenic approaches, and CRISPR-Cas9 genome-editing.

Promising Sources of Plant-Derived Polyunsaturated Fatty Acids: A Narrative Review

(1) Background: Polyunsaturated fatty acids (PUFAs) are known for their ability to protect against numerous metabolic disorders. The consumption of oily fish is the main source of PUFAs in human nutrition and is commonly used for supplement production. However, seafood is an overexploited source that cannot be guaranteed to cover the global demands. Furthermore, it is not consumed by everyone for ecological, economic, ethical, geographical and taste reasons. The growing demand for natural dietary sources of PUFAs suggests that current nutritional sources are insufficient to meet global needs, and less and less will be. Therefore, it is crucial to find sustainable sources that are acceptable to all, meeting the world population's needs. (2) Scope: This review aims to evaluate the recent evidence about alternative plant sources of essential fatty acids, focusing on long-chain omega-3 (n-3) PUFAs. (3) Method: A structured search was performed on the PubMed search engine to select available human data from interventional studies using omega-3 fatty acids of non-animal origin. (4) Results: Several promising sources have emerged from the literature, such as algae, microorganisms, plants rich in stearidonic acid and GM plants. However, the costs, acceptance and adequate formulation deserve further investigation.

New alternative sources of omega-3 fish oil

Long-chain omega-3 polyunsaturated fatty acids such as eicosapentaenoic and docosahexaenoic acids play an important role in brain growth and development, as well as in the health of the body. These fatty acids are traditionally found in seafood, such as fish, fish oils, and algae. They can also be added to food or consumed through dietary supplements. Due to a lack of supply to meet current demand and the potential for adverse effects from excessive consumption of fish and seafood, new alternatives are being sought to achieve the recommended levels in a safe and sustainable manner. New sources have been studied and new production mechanisms have been developed. These new proposals, as well as the importance of these fatty acids, are discussed in this paper.

Using field evaluation and systematic iteration to rationalize the accumulation of omega-3 long-chain polyunsaturated fatty acids in transgenic Camelina sativa

The Brassicaceae Camelina sativa (gold of pleasure) is now an established niche crop and being used as a transgenic host for a range of novel seed traits. Most notable of these is the accumulation of omega-3 long-chain polyunsaturates such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), fatty acids normally only found in marine organisms. As part of continued efforts to optimize the accumulation of these non-native fatty acids via seed-specific expression of algal genes, a new series of iterative constructs was built and introduced into Camelina. Seed fatty acid composition was determined, and the presence of EPA and DHA was confirmed. To provide an additional level of evaluation, full environmental release was carried out on selected events, providing a real-world gauntlet against which to assess the performance of these novel lines. Composition of the seed oil triacylglycerol was determined by mass spectrometry, allowing for conclusions as to the contribution of different activities to the final accumulation of EPA and DHA. Since these data were derived from field-grown material, they also represent a robust demonstration of the stability of the omega-3 LC-PUFA trait in Camelina. We propose that field trialling should be routinely incorporated in the plant synthetic biology 'design-build-test-learn' cycle.

Engineering an oilseed crop for hyper-accumulation of carotenoids in the seeds without using a traditional marker gene

Ketocarotenoids were synthesized successfully in Camelina sativa seeds by genetic modification without using a traditional selection marker genes. This method provided an interesting tool for metabolic engineering of seed crops. Camelina sativa (L.) Crantz is an important oil crop with many excellent agronomic traits. This model oil plant has been exploited to accumulate value-added bioproducts using genetic manipulation that depends on antibiotic- or herbicide-based selection marker genes (SMG), one of the major concerns for genetically modified foods. Here we reported metabolic engineering of C. sativa to synthesize red ketocarotenoids that could serve as a reporter to visualize transgenic events without using a traditional SMG. Overexpression of a non-native β-carotene ketolase gene coupled with three other carotenogenous genes (phytoene synthase, β-carotene hydroxylase, and Orange) in C. sativa resulted in production of red seeds that were visibly distinguishable from the normal yellow ones. Constitutive expression of the transgenes led to delayed plant development and seed germination. In contrast, seed-specific transformants demonstrated normal growth and seed germination despite the accumulation of up to 70-fold the level of carotenoids in the seeds compared to the controls, including significant amounts of astaxanthin and keto-lutein. As a result, the transgenic seed oils exhibited much higher antioxidant activity. No significant changes were found in the profiles of fatty acids between transgenic and control seeds. This study provided an interesting tool for metabolic engineering of seed crops without using a disputed SMG.

Synthesis of C20-38 Fatty Acids in Plant Tissues

Very-long-chain fatty acids (VLCFA) are involved in a number of important plant physiological functions. Disorders in the expression of genes involved in the synthesis of VLCFA lead to a number of phenotypic consequences, ranging from growth retardation to the death of embryos. The elongation of VLCFA in the endoplasmic reticulum (ER) is carried out by multiple elongase complexes with different substrate specificities and adapted to the synthesis of a number of products required for a number of metabolic pathways. The information about the enzymes involved in the synthesis of VLCFA with more than 26 atoms of Carbon is rather poor. Recently, genes encoding enzymes involved in the synthesis of both regular-length fatty acids and VLCFA have been discovered and investigated. Polyunsaturated VLCFA in plants are formed mainly by 20:1 elongation into new monounsaturated acids, which are then imported into chloroplasts, where they are further desaturated. The formation of saturated VLCFA and their further transformation into a number of aliphatic compounds included in cuticular waxes and suberin require the coordinated activity of a large number of different enzymes.

Realizing the Potential of Camelina sativa as a Bioenergy Crop for a Changing Global Climate

Camelina sativa (L.) Crantz. is an annual oilseed crop within the Brassicaceae family. C. sativa has been grown since as early as 4000 BCE. In recent years, C. sativa received increased attention as a climate-resilient oilseed, seed meal, and biofuel (biodiesel and renewable or green diesel) crop. This renewed interest is reflected in the rapid rise in the number of peer-reviewed publications (>2300) containing “camelina” from 1997 to 2021. An overview of the origins of this ancient crop and its genetic diversity and its yield potential under hot and dry growing conditions is provided. The major biotic barriers that limit C. sativa production are summarized, including weed control, insect pests, and fungal, bacterial, and viral pathogens. Ecosystem services provided by C. sativa are also discussed. The profiles of seed oil and fatty acid composition and the many uses of seed meal and oil are discussed, including food, fodder, fuel, industrial, and medical benefits. Lastly, we outline strategies for improving this important and versatile crop to enhance its production globally in the face of a rapidly changing climate using molecular breeding, rhizosphere microbiota, genetic engineering, and genome editing approaches.

Diverting phenylpropanoid pathway flux from sinapine to produce industrially useful 4-vinyl derivatives of hydroxycinnamic acids in Brassicaceous oilseeds

Sinapine (sinapoylcholine) is an antinutritive phenolic compound that can account for up to 2% of seed weight in brassicaceous oilseed crops and reduces the suitability of their protein-rich seed meal for use as animal feed. Sinapine biosynthesis draws on hydroxycinnamic acid precursors produced by the phenylpropanoid pathway. The 4-vinyl derivatives of several hydroxycinnamic acids have industrial applications. For example, 4-vinyl phenol (4-hydroxystyrene) is a building block for a range of synthetic polymers applied in resins, inks, elastomers, and coatings. Here we have expressed a modified bacterial phenolic acid decarboxylase (PAD) in developing seed of Camelina sativa to redirect phenylpropanoid pathway flux from sinapine biosynthesis to the production of 4-vinyl phenols. PAD expression led to a ∼95% reduction in sinapine content in seeds of both glasshouse and field grown C. sativa and to an accumulation of 4-vinyl derivatives of hydroxycinnamic acids, primarily as glycosides. The most prevalent aglycone was 4-vinyl phenol, but 4-vinyl guaiacol, 6-hydroxy-4-vinyl guaiacol and 4-vinylsyringol (Canolol) were also detected. The molar quantity of 4-vinyl phenol glycosides was more than twice that of sinapine in wild type seeds. PAD expression was not associated with an adverse effect on seed yield, harvest index, seed morphology, storage oil content or germination in either glasshouse or field experiments. Our data show that expression of PAD in brassicaceous oilseeds can supress sinapine accumulation, diverting phenylpropanoid pathway flux into 4-vinyl phenol derivatives, thereby also providing a non-petrochemical source of this class of industrial chemicals.

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A phenolic acid decarboxylase was expressed in developing Camelina sativa seeds.

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Production of the antinutritive phenolic compound sinapine was reduced by 95%.

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Hydroxycinnamic acids were converted to 4-vinyl phenols and accumulated as glycosides.

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The quantity of 4-vinyl phenols was more than twice that of sinapine in wild type.

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Seed yield appeared not to be affected in either glasshouse or field experiments.

Plant Molecular Farming, a Tool for Functional Food Production

The demand of functional food is increasing for improving human health. Plant molecular farming (PMF) employs plants as bioreactors for the production of pharmaceuticals. Now PMF has been used to produce antibodies, vaccines, and medicinal proteins, but it has not been well-studied for production of nutraceuticals and functional food. In this perspective, we extend the concept of PMF, present an updated overview of PMF for functional food development, including the progress, problem, and strategy, and then speculate how to use the PMF strategy to produce functional foods, especially with four major staple food crops (rice, wheat, maize, and soybean). Finally, we discuss the opportunities and challenges of PMF on functional food production in the future.

Copper-Promoted Conjugate Addition of Carboxylic Acids to Ethenesulfonyl Fluoride (ESF) for Constructing Aliphatic Sulfonyl Fluorides

A CuO-promoted direct hydrocarboxylation of ethenesulfonyl fluoride (ESF) was developed using carboxylic acid as a nucleophile under mild conditions. A variety of molecules containing both ester group and aliphatic sulfonyl fluoride moiety exhibit great potential in medicinal chemistry and chemical biology. Furthermore, the modification of the known drugs Ibuprofen and Aspirin was also demonstrated.

Dietary Supplementation with Transgenic Camelina sativa Oil Containing 20:5n-3 and 22:6n-3 or Fish Oil Induces Differential Changes in the Transcriptome of CD3+ T Lymphocytes

Eicosapentaenoic acid (20:5n-3) and docosahexaenoic acid (22:6n-3) are important for leukocyte function. This study investigated whether consuming transgenic Camelina sativa (tCSO) seed oil containing both 20:5n-3 and 22:6n-3 is as effective as fish oil (FO) for increasing the 20:5n-3 and 22:6n-3 content of leukocytes and altering mitogen-induced changes to the T cell transcriptome. Healthy adults (n = 31) consumed 450 mg/day of 20:5n-3 plus 22:6n-3 from either FO or tCSO for 8 weeks. Blood was collected before and after the intervention. 20:5n-3 and 22:6n-3 incorporation from tCSO into immune cell total lipids was comparable to FO. The relative expression of the transcriptomes of mitogen-stimulated versus unstimulated T lymphocytes in a subgroup of 16 women/test oil showed 4390 transcripts were differentially expressed at Baseline (59% up-regulated), 4769 (57% up-regulated) after FO and 3443 (38% up-regulated) after tCSO supplementation. The 20 most altered transcripts after supplementation differed between test oils. The most altered pathways were associated with cell proliferation and immune function. In conclusion, 20:5n-3 and 22:6n-3 incorporation into immune cells from tCSO was comparable to FO and can modify mitogen-induced changes in the T cell transcriptome, contingent on the lipid matrix of the oil.

Evolutionary trade-offs at the Arabidopsis WRR4A resistance locus underpin alternate Albugo candida race recognition specificities

The oomycete Albugo candida causes white rust of Brassicaceae, including vegetable and oilseed crops, and wild relatives such as Arabidopsis thaliana. Novel White Rust Resistance (WRR) genes from Arabidopsis enable new insights into plant/parasite co-evolution. WRR4A from Arabidopsis accession Columbia (Col-0) provides resistance to many but not all white rust races, and encodes a nucleotide-binding, leucine-rich repeat immune receptor. Col-0 WRR4A resistance is broken by AcEx1, an isolate of A. candida. We identified an allele of WRR4A in Arabidopsis accession Øystese-0 (Oy-0) and other accessions that confers full resistance to AcEx1. WRR4AOy-0 carries a C-terminal extension required for recognition of AcEx1, but reduces recognition of several effectors recognized by the WRR4ACol-0 allele. WRR4AOy-0 confers full resistance to AcEx1 when expressed in the oilseed crop Camelina sativa.

Plant and algal lysophosphatidic acid acyltransferases increase docosahexaenoic acid accumulation at the sn-2 position of triacylglycerol in transgenic Arabidopsis seed oil

Although docosahexaenoic acid (DHA), an important dietary omega-3 polyunsaturated fatty acid (PUFA), is at present primarily sourced from marine fish, bioengineered crops producing DHA may offer a more sustainable and cost-effective source. DHA has been produced in transgenic oilseed crops, however, DHA in seed oil primarily occupies the sn-1/3 positions of triacylglycerol (TAG) with relatively low amounts of DHA in the sn-2 position. To increase the amount of DHA in the sn-2 position of TAG and in seed oil, putative lysophosphatidic acid acyltransferases (LPAATs) were identified and characterized from the DHA-producing alga Schizochytrium sp. and from soybean (Glycine max). The affinity-purified proteins were confirmed to have LPAAT activity. Expression of the Schizochytrium or soybean LPAATs in DHA-producing Arabidopsis expressing the Schizochytrium PUFA synthase system significantly increased the total amount of DHA in seed oil. A novel sensitive band-selective heteronuclear single quantum coherence (HSQC) NMR method was developed to quantify DHA at the sn-2 position of glycerolipids. More than two-fold increases in sn-2 DHA were observed for Arabidopsis lines expressing Schizochytrium or soybean LPAATs, with one Schizochytrium LPAAT driving DHA accumulation in the sn-2 position to 61% of the total DHA. Furthermore, expression of a soybean LPAAT led to a redistribution of DHA-containing TAG species, with two new TAG species identified. Our results demonstrate that transgenic expression of Schizochytrium or soybean LPAATs can increase the proportion of DHA at the sn-2 position of TAG and the total amount of DHA in the seed oil of a DHA-accumulating oilseed plant. Additionally, the band-selective HSQC NMR method that we developed provides a sensitive and robust method for determining the regiochemistry of DHA in glycerolipids. These findings will benefit the advancement of sustainable sources of DHA via transgenic crops such as canola and soybean.

Synaptotagmins at the endoplasmic reticulum-plasma membrane contact sites maintain diacylglycerol homeostasis during abiotic stress

Endoplasmic reticulum-plasma membrane contact sites (ER-PM CS) play fundamental roles in all eukaryotic cells. Arabidopsis thaliana mutants lacking the ER-PM protein tether synaptotagmin1 (SYT1) exhibit decreased PM integrity under multiple abiotic stresses, such as freezing, high salt, osmotic stress, and mechanical damage. Here, we show that, together with SYT1, the stress-induced SYT3 is an ER-PM tether that also functions in maintaining PM integrity. The ER-PM CS localization of SYT1 and SYT3 is dependent on PM phosphatidylinositol-4-phosphate and is regulated by abiotic stress. Lipidomic analysis revealed that cold stress increased the accumulation of diacylglycerol at the PM in a syt1/3 double mutant relative to wild-type while the levels of most glycerolipid species remain unchanged. In addition, the SYT1-green fluorescent protein fusion preferentially binds diacylglycerol in vivo with little affinity for polar glycerolipids. Our work uncovers a SYT-dependent mechanism of stress adaptation counteracting the detrimental accumulation of diacylglycerol at the PM produced during episodes of abiotic stress.

Ectopic expression of cDNAs from larkspur (Consolida ajacis) for increased synthesis of gondoic acid (cis-11 eicosenoic acid) and its positional redistribution in seed triacylglycerol of Camelina sativa

A β-ketoacyl-ACP-synthase II (KAS2) like enzyme and a lysophosphatidic acid acyltransferase (LPAT2) from Consolida ajacis catalyze gondoic acid biosynthesis and incorporation into the sn-2 position of seed TAG in engineered Camelina sativa. Gondoic acid (cis-11 eicosenoic acid, 20:1∆11) is the predominant very-long-chain fatty acid (VLCFA) in camelina (Camelina sativa) seed oil accounting for 12-15% of total triacylglycerol fatty acids. To explore the feasibility of engineering increased levels of this fatty acid in camelina seed, oils from a range of plant species were analyzed to identify those producing 20-Carbon (C20) fatty acids as the only VLCFAs in their seed oil. Seeds of Consolida and Delphinium species (Ranunculaceae) were found to contain moderate levels (0.2% to 25.5%) of C20 fatty acids without accompanying longer chain fatty acids. The C20 fatty acids were abundant in both sn-2 and sn-1/3 positions of seed TAG in Consolida, but were largely absent from the sn-2 position in Delphinium seed TAG. Through generation of a developing seed transcriptome, sequences were identified and cDNAs amplified from Consolida ajacis encoding a β-ketoacyl-ACP-synthase II like protein (CaKAS2B) that lacked a predicted chloroplast transit peptide, and two homologues of Arabidopsis thaliana lysophosphatidic acid acyltransferase 2 (CaLPAT2a and CaLPAT2b). Expression of CaKAS2B in conventional (WT) camelina and a line previously engineered for high seed oleic acid content (HO) resulted in increased seed VLCFA content. Total VLCFA levels were raised from 24 to 35% and from 7 to 23% in T3 seed from representative transformants in the WT and HO backgrounds, respectively. Gondoic acid was the predominant VLCFA in transformed HO lines with low endogenous cytoplasmic fatty acid elongation activity, suggesting limited capacity of CaKAS2B to elongate beyond C20. Expression in camelina of CaLPAT2b resulted in significantly increased C20-VLCFA esterification at the sn-2 position of seed TAG with VLCFA levels of 33.8% in this position in one transformed line compared to 0.3% at sn-2 in the corresponding control line. Only small changes in total seed VLCFA content were observed in transformed lines implying that increased VLCFA esterification capacity in camelina results in positional redistribution of VLCFAs but does not significantly enhance flux through the fatty acid elongation pathway. The full potential of CaKAS2B and CaLPAT2a for the engineering of high gondoic acid levels in camelina remains to be determined. Seed fatty acid composition of Consolida and Delphinium also provides information that may be of value in the systematics of the Ranunculaceae.

Techniques for the Measurement of Molecular Species of Acyl-CoA in Plants and Microalgae

The acyl-CoA pool is pivotal in cellular metabolism. The ability to provide reliable estimates of acyl-CoA abundance and distribution between molecular species in plant tissues and microalgae is essential to our understanding of lipid metabolism and acyl exchange. Acyl-CoAs are typically found in low abundance and require specific methods for extraction, separation and detection. Here we describe methods for acyl-CoA extraction and measurement in plant tissues and microalgae, with a focus on liquid chromatography hyphenated to detection techniques including ultraviolet (UV), fluorescence and mass spectrometry (MS). We address the resolution of isobaric species and the selection of columns needed to achieve this, including the analysis of branched chain acyl-CoA thioesters. For MS analyses, we describe diagnostic ions for the identification of acyl-CoA species and how these can be used for both discovery of new species (data dependent acquisition) and routine quantitation (triple quadrupole MS with multiple reaction monitoring).

Characterization of ω3 fatty acid desaturases from oomycetes and their application toward eicosapentaenoic acid production in Mortierella alpina

ω3 Polyunsaturated fatty acids are currently obtained mainly from fisheries; thus, sustainable alternative sources such as oleaginous microorganisms are required. Here, we describe the isolation, characterization, and application of 3 novel ω3 desaturases with ω3 polyunsaturated fatty acid-producing activity at ordinary temperatures (28 °C). First, we selected Pythium sulcatum and Plectospira myriandra after screening for oomycetes with high eicosapentaenoic acid/arachidonic acid ratios and isolated the genes psulω3 and pmd17, respectively, which encode ω3 desaturases. Subsequent characterization showed that PSULω3 exhibited ω3 desaturase activity on both C18 and C20 ω6 polyunsaturated fatty acids while PMD17 exhibited ω3 desaturase activity exclusively on C20 ω6 polyunsaturated fatty acids. Expression of psulω3 and pmd17 in the arachidonic acid-producer Mortierella alpina resulted in transformants that produced eicosapentaenoic acid/total fatty acid values of 38% and 40%, respectively, at ordinary temperatures. These ω3 desaturases should facilitate the construction of sustainable ω3 polyunsaturated fatty acid sources.

Photoautotrophic production of eicosapentaenoic acid

Eicosapentaenoic acid (EPA) is an omega-3 fatty acid which is an essential nutrient for both humans and animals. This review examines the global need for EPA, both in human nutrition and aquaculture. The potential shortfall in supply of this important nutrient as well as sustainability issues with wild-caught fish have generated increased interest into alternative sources of EPA. Various approaches are summarized, including heterotrophic production and the use of genetically modified microorganisms and plants. Studies on photoautotrophic production of EPA are extensively reviewed. Widely used species for large-scale production of EPA includes Phaeodactylum tricornutum and Nannochloropsis due to their robustness and relatively high growth rates and EPA content (typically 5% of dry biomass). Approaches for large-scale production have also been reviewed. Closed reactors like flat panels, tubular reactors and bubble columns may be the most suitable due to their high productivity. However, there is no agreement in the literature as to which design generates the lowest cost of production. The economics of the process has also been examined. The best estimates for large-scale (100 hectare) plants give EPA prices of the order 39-90 USD per kilogram. This is approximately ten times higher than the price of EPA derived from fish oil. Potential avenues for lowering the cost are highlighted, along with the need to better understand the advantages and disadvantages of different EPA production methods from a more holistic perspective.

Genetically modified plants are an alternative to oily fish for providing n-3 polyunsaturated fatty acids in the human diet: A summary of the findings of a Biotechnology and Biological Sciences Research Council funded project

The n-3 polyunsaturated fatty acids (PUFA) present primarily in oily fish, namely eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), are important components of cell membranes and that are needed for normal development and cell function. Humans have very limited capacity for EPA and DHA synthesis from α-linolenic acid and so they must be obtained pre-formed from the diet. However, perceived unpalatability of oily fish and fish oil concerns about contamination with environmental pollutants, dietary choices that exclude fish and animal products, and price limit the effectiveness of recommendations for EPA and DHA intakes. Moreover, marine sources of EPA and DHA are diminishing in the face of increasing demands. Therefore, an alternative source of EPA and DHA is needed that is broadly acceptable, can be upscaled and is sustainable. This review discusses these challenges and, using findings from recent nutritional trials, explains how they may be overcome by seed oils from transgenic plants engineered to produce EPA and DHA. Trials in healthy men and women assessed the acute uptake and appearance in blood over 8 hours of EPA and DHA from transgenic Camelina sativa compared to fish oil, and the incorporation of these PUFA into blood lipids after dietary supplementation. The findings showed that postprandial EPA and DHA incorporation into blood lipids and accumulation in plasma lipids after dietary supplementation was as good as that achieved with fish oil. The oil derived from this transgenic plant was well tolerated. This review also discusses the implications for human nutrition, marine ecology and agriculture.

Increased expression of fatty acid and ABC transporters enhances seed oil production in camelina

BACKGROUND

Lipid transporters play an essential role in lipid delivery and distribution, but their influence on seed oil production in oilseed crops is not well studied.

RESULTS

Here, we examined the effect of two lipid transporters, FAX1 (fatty acid export1) and ABCA9 (ATP-binding cassette transporter subfamily A9) on oil production and lipid metabolism in the oilseed plant Camelina sativa. Overexpression (OE) of FAX1 and ABCA9 increased seed weight and size, with FAX1-OEs and ABCA9-OEs increasing seed length and width, respectively, whereas FAX1/ABCA9-OEs increasing both. FAX1-OE and ABCA9-OE displayed additive effects on seed oil content and seed yield. Also, OE of FAX1 and ABCA9 affected membrane lipid composition in developing pods, especially on phosphatidylcholine, phosphatidylethanolamine, and phosphatidylglycerol. The expression of some genes involved in seed oil synthesis, such as DGAT2, PDAT1, and LEC1, was increased in developing seeds of FAX1- and/or ABCA9-OEs.

CONCLUSION

These results indicate that increased expression of FAX1 and ABCA9 can potentially be applied to improving camelina oil production.

Microalgae n-3 PUFAs Production and Use in Food and Feed Industries

N-3 polyunsaturated fatty acids (n-3 PUFAs), and especially eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), are essential compounds for human health. They have been proven to act positively on a panel of diseases and have interesting anti-oxidative, anti-inflammatory or anti-cancer properties. For these reasons, they are receiving more and more attention in recent years, especially future food or feed development. EPA and DHA come mainly from marine sources like fish or seaweed. Unfortunately, due to global warming, these compounds are becoming scarce for humans because of overfishing and stock reduction. Although increasing in recent years, aquaculture appears insufficient to meet the increasing requirements of these healthy molecules for humans. One alternative resides in the cultivation of microalgae, the initial producers of EPA and DHA. They are also rich in biochemicals with interesting properties. After defining macro and microalgae, this review synthesizes the current knowledge on n-3 PUFAs regarding health benefits and the challenges surrounding their supply within the environmental context. Microalgae n-3 PUFA production is examined and its synthesis pathways are discussed. Finally, the use of EPA and DHA in food and feed is investigated. This work aims to define better the issues surrounding n-3 PUFA production and supply and the potential of microalgae as a sustainable source of compounds to enhance the food and feed of the future.

Oxidation of polyunsaturated fatty acids to produce lipid mediators

The chemistry, biochemistry, pharmacology and molecular biology of oxylipins (defined as a family of oxygenated natural products that are formed from unsaturated fatty acids by pathways involving at least one step of dioxygen-dependent oxidation) are complex and occasionally contradictory subjects that continue to develop at an extraordinarily rapid rate. The term includes docosanoids (e.g. protectins, resolvins and maresins, or specialized pro-resolving mediators), eicosanoids and octadecanoids and plant oxylipins, which are derived from either the omega-6 (n-6) or the omega-3 (n-3) families of polyunsaturated fatty acids. For example, the term eicosanoid is used to embrace those biologically active lipid mediators that are derived from C₂₀ fatty acids, and include prostaglandins, thromboxanes, leukotrienes, hydroxyeicosatetraenoic acids and related oxygenated derivatives. The key enzymes for the production of prostanoids are prostaglandin endoperoxide H synthases (cyclo-oxygenases), while lipoxygenases and oxidases of the cytochrome P450 family produce numerous other metabolites. In plants, the lipoxygenase pathway from C₁₈ polyunsaturated fatty acids yields a variety of important products, especially the jasmonates, which have some comparable structural features and functions. Related oxylipins are produced by non-enzymic means (isoprostanes), while fatty acid esters of hydroxy fatty acids (FAHFA) are now being considered together with the oxylipins from a functional perspective. In all kingdoms of life, oxylipins usually act as lipid mediators through specific receptors, have short half-lives and have functions in innumerable biological contexts.

Functional characterization of an novel acyl-CoA:diacylglycerol acyltransferase 3-3 (CsDGAT3-3) gene from Camelina sativa

Diacylglycerol acyltransferases (DGAT) catalyze the final committed step of de novo biosynthesis of triacylglycerol (TAG) in plant seeds. This study was to functionally characterize DGAT3 genes in Camelina sativa, an important oil crops accumulating high levels of unsaturated fatty acids (UFAs) in seeds. Three camelina DGAT3 genes (CsDGAT3-1, CsDGAT3-2 and CsDGAT3-3) were identified, and the encoded proteins were predicted to be cytosolic-soluble proteins present as a homodimer containing the 2Fe-2S domain. They had divergent expression patterns in various tissues, suggesting that they may function in tissue-specific manner with CsDGAT3-1 in roots, CsDGAT3-2 in flowers and young seedlings, and CsDGAT3-3 in developing seeds. Functional complementation assay in yeast demonstrated that CsDGAT3-3 restored TAG synthesis. TAG content and UFAs, particularly eicosenoic acid (EA, 20:1n-9) were largely increased by adding exogenous UFAs in the yeast medium. Further heterogeneously transient expression in N. benthamiana leaves and seed-specific expression in tobacco seeds indicated that CsDGAT3-3 significantly enhanced oil and UFA accumulation with much higher level of EA. Overall, CsDGAT3-3 exhibited a strong abilty catalyzing TAG synthesis and high substrate preference for UFAs, especially for 20:1n-9. The present data provide new insights for further understanding oil biosynthesis mechanism in camelina seeds, indicating that CsDGAT3-3 may have practical applications for increasing both oil yield and quality.

Oil from transgenic Camelina sativa as a source of EPA and DHA in feed for European sea bass (Dicentrarchus labrax L.)

Aquaculture, the fastest growing food production sector cannot continue to rely on finite stocks of marine fish as the primary source of the omega-3 (n-3) long-chain polyunsaturated fatty acids (LC-PUFA), eicosapentaenoic acid (EPA; 20:5n3) and docosahexaenoic acid (DHA; 22:6n-3), for feeds. A four-month feeding trial was conducted to investigate the impact of a de novo oil, with high levels of EPA and DHA, obtained from transgenic Camelina sativa on growth performance, tissue fatty acid profiles, and expression of lipid metabolism genes when used as a replacement for fish oil in feed for European seabass (Dicentrachus labrax). Triplicate groups of 50 juvenile fish (initial weight 16.7 ± 0.92 g) per tank were fed for 4 months with one of three isolipidic and isoproteic experimental diets consisting of a standard diet containing a commercial blend of fish oil and rapeseed oil (CFO), a diet containing transgenic Camelina oil (TCO), or a blend of fish oil and rapeseed oil with enhanced levels of EPA and DHA (EFO) formulated to match the n-3 LC-PUFA profile of the TCO feed. Final weight of fish fed the GM-derived oil was not different to fish fed either CFO or EFO. Slight lower growth performance of fish fed TCO at the beginning of the trial was related to transient reduced feed intake, possibly caused by glucosinolates in the raw Camelina sativa oil. The GM-derived oil improved the nutritional quality of the fish fillet by enhancing total n-3 PUFA levels compared to the fish fed the other two feeds, and maintained flesh EPA and DHA at the same levels as in fish fed the diets containing fish oil. The metabolic response in liver and intestine was generally relatively mild although diets TCO and EFO seemed to trigger a metabolic response consisting of an up-regulation of both β-oxidation (cpt1a) and fatty acid transport (fabp1), possibly reflecting higher levels of LC-PUFA. Overall, the present study indicated that an oil of terrestrial origin, Camelina sativa, when engineered to contain high levels of EPA and DHA can replace fish oil in feeds for European seabass with no detrimental impact on growth or feed efficiency, while also maintaining or increasing tissue n-3 LC-PUFA contents.

A direct synthesis of carboxylic acids via platinum-catalysed hydroxycarbonylation of olefins

A selective platinum-catalysed hydroxycarbonylation of aliphatic olefins has been achieved.

Effect of dietary oil from Camelina sativa on the growth performance, fillet fatty acid profile and gut microbiome of gilthead Sea bream (Sparus aurata)

BACKGROUND

In the last two decades, research has focused on testing cheaper and sustainable alternatives to fish oil (FO), such as vegetable oils (VO), in aquafeeds. However, FO cannot be entirely replaced by VOs due to their lack of omega-3 (n-3) long-chain polyunsaturated fatty acids (LC-PUFA), particularly eicosapentaenoic (EPA; 20:5n-3) and docosahexaenoic (DHA; 22:6n-3) acids. The oilseed plant, Camelina sativa, may have a higher potential to replace FO since it can contains up to 40% of the omega-3 precursors α-linolenic acid (ALA; 18:3n-3) and linoleic acid (LA; 18:2n-6).

METHODS

A 90-day feeding trial was conducted with 600 gilthead sea bream (Sparus aurata) of 32.92 ±  0.31 g mean initial weight fed three diets that replaced 20%, 40% and 60% of FO with CO and a control diet of FO. Fish were distributed into triplicate tanks per diet and with 50 fish each in a flow-through open marine system. Growth performance and fatty acid profiles of the fillet were analysed. The Illumina MiSeq platform for sequencing of 16S rRNA gene and Mothur pipeline were used to identify bacteria in the faeces, gut mucosa and diets in addition to metagenomic analysis by PICRUSt.

RESULTS AND CONCLUSIONS

The feed conversion rate and specific growth rate were not affected by diet, although final weight was significantly lower for fish fed the 60% CO diet. Reduced final weight was attributed to lower levels of EPA and DHA in the CO ingredient. The lipid profile of fillets were similar between the dietary groups in regards to total saturated, monounsaturated, PUFA (n-3 and n-6), and the ratio of n-3/n-6. Levels of EPA and DHA in the fillet reflected the progressive replacement of FO by CO in the diet and the EPA was significantly lower in fish fed the 60% CO diet, while ALA was increased. Alpha and beta-diversities of gut bacteria in both the faeces and mucosa were not affected by any dietary treatment, although a few indicator bacteria, such as Corynebacterium and Rhodospirillales, were associated with the 60% CO diet. However, lower abundance of lactic acid bacteria, specifically Lactobacillus, in the gut of fish fed the 60% CO diet may indicate a potential negative effect on gut microbiota. PICRUSt analysis revealed similar predictive functions of bacteria in the faeces and mucosa, although a higher abundance of Corynebacterium in the mucosa of fish fed 60% CO diet increased the KEGG pathway of fatty acid synthesis and may act to compensate for the lack of fatty acids in the diet. In summary, this study demonstrated that up to 40% of FO can be replaced with CO without negative effects on growth performance, fillet composition and gut microbiota of gilthead sea bream.

Enhancing the Nutritional Quality of Major Food Crops Through Conventional and Genomics-Assisted Breeding

Nutritional stress is making over two billion world population malnourished. Either our commercially cultivated varieties of cereals, pulses, and oilseed crops are deficient in essential nutrients or the soils in which these crops grow are becoming devoid of minerals. Unfortunately, our major food crops are poor sources of micronutrients required for normal human growth. To overcome the problem of nutritional deficiency, greater emphasis should be laid on the identification of genes/quantitative trait loci (QTLs) pertaining to essential nutrients and their successful deployment in elite breeding lines through marker-assisted breeding. The manuscript deals with information on identified QTLs for protein content, vitamins, macronutrients, micro-nutrients, minerals, oil content, and essential amino acids in major food crops. These QTLs can be utilized in the development of nutrient-rich crop varieties. Genome editing technologies that can rapidly modify genomes in a precise way and will directly enrich the nutritional status of elite varieties could hold a bright future to address the challenge of malnutrition.

Heterologous Production of Polyunsaturated Fatty Acids in E. coli Using Δ5-Desaturase Gene from Microalga Isochrysis Sp

Eicosapentaenoic acid (EPA) and arachidonic acid (ARA) are long-chain polyunsaturated fatty acids (PUFAs) that play a significant role in human growth and development, which deficiency can trigger several metabolic-related diseases. Since the availability of PUFA sources is limited, there arises a need to explore alternative sources. Therefore, the present study aimed to investigate whether an Escherichia coli which are engineered with Δ5Des-Iso gene isolated from Isochrysis sp. could be utilized to synthesize PUFAs. Full-length gene Δ5Des-Iso (1149 bp) was isolated from Isochrysis sp. that encodes 382 amino acids and identified as Δ5-desatruase gene using different bioinformatic analysis. Heterologous gene expression was carried out in E. coli having Δ5Des-Iso with precursor fatty acids. The Δ5Des-Iso produced novel fatty acids of EPA (ω-3) and ARA (ω-6) as respective products were identified by GC-MS. Gene expression and PUFA synthesis in E. coli were optimized by temperature, time, and concentrations of precursor fatty acid substrates. Δ5Des-Iso RNA transcript level was inversely proportional to the time and fatty acid synthesis. And, the significant production of EPA (4.1 mg/g) and ARA (8.3 mg/g) in total fatty acids was observed in E. coli grown at 37 °C for 24 h with 25 μM of external fatty acid substrate as an optimum growth conditions. E. coli could be used as alternative organism to synthesis PUFAs and widely applicable in many nutraceuticals and pharmaceuticals industry for human use.

Dietary supplementation with seed oil from transgenic Camelina sativa induces similar increments in plasma and erythrocyte DHA and EPA to fish oil in healthy humans

EPA and DHA are required for normal cell function and can also induce health benefits. Oily fish are the main source of EPA and DHA for human consumption. However, food choices and concerns about the sustainability of marine fish stocks limit the effectiveness of dietary recommendations for EPA + DHA intakes. Seed oils from transgenic plants that contain EPA + DHA are a potential alternative source of EPA and DHA. The present study investigated whether dietary supplementation with transgenic Camelina sativa seed oil (CSO) that contained EPA and DHA was as effective as fish oil (FO) in increasing EPA and DHA concentrations when consumed as a dietary supplement in a blinded crossover study. Healthy men and women (n 31; age 53 (range 20-74) years) were randomised to consume 450 mg/d EPA + DHA provided either as either CSO or FO for 8 weeks, followed by 6 weeks washout and then switched to consuming the other test oil. Fasting venous blood samples were collected at the start and end of each supplementation period. Consuming the test oils significantly (P < 0·05) increased EPA and DHA concentrations in plasma TAG, phosphatidylcholine and cholesteryl esters. There were no significant differences between test oils in the increments of EPA and DHA. There was no significant difference between test oils in the increase in the proportion of erythrocyte EPA + DHA (CSO, 12 %; P < 0·0001 and FO, 8 %; P = 0·02). Together, these findings show that consuming CSO is as effective as FO for increasing EPA and DHA concentrations in humans.

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

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.

Biotechnology tools and applications for development of oilseed crops with healthy vegetable oils

Vegetable oils, consisting principally of triacylglycerols (TAG), are major sources of calories and essential fatty acids in the human diet. The fatty acid composition of TAG is a primary determinant of the nutritional quality and health-promoting properties of vegetable oils. TAG fatty acid composition also affects the functionality and properties of vegetable oils in food applications and in food processing and preparation. Vegetable oils with improved nutritional and functional properties have been developed for oilseed crops by selection and breeding of fatty acid biosynthetic mutants. These efforts have been effective at generating vegetable oils with altered relative amounts of saturated and unsaturated fatty acids in seed TAG, but are constrained by insufficient genetic diversity for producing oils with "healthy" fatty acids that are not typically found in major oilseeds. The development and application of biotechnological tools have instead enabled the generation of oilseeds that produce novel fatty acid compositions with improved nutritional value by the introduction of genes from alternative sources, including plants, bacteria, and fungi. These tools have also allowed the generation of desired oil compositions that have proven difficult to obtain by breeding without compromised performance in selected oilseed crops. Here, we review biotechnological tools for increasing crop genetic diversity and their application for commercial or proof-of-principal development of oilseeds with expanded utility for food and feed applications and higher value nutritional and nutraceutical markets.