Co-expressing Eranthis hyemalis lysophosphatidic acid acyltransferase 2 and elongase improves two very long chain polyunsaturated fatty acid production in Brassica carinata

Analysis of Coix Seed Oil Biosynthesis Facilitates the Identification of Lysophosphatidic Acid Acyltransferase

Coix seed oil (CSO) is a natural substance with significant anticancer potential. However, the molecular mechanism and the gene regulatory network of lipid biosynthesis were not identified in Coix seed. Here, a comprehensive transcriptome analysis was conducted on two Coix varieties with different lipid contents. The results revealed that a total of 48,110 genes were generated by de novo assembly, of which 84.45% genes were successfully annotated by the database. Based on functional annotation and gene expression, the metabolic network of crucial genes for oil accumulation and fatty acid (FA) synthesis in Coix seed has been successfully established, and it has been confirmed that lysophosphatidic acid acyltransferase (LPAT) in triacylglycerol (TAG) biosynthesis contributed to the changes in the content of FAs and had a significant selective binding ability to unsaturated fatty acids (UFAs) by the heterologous expression of yeast. Our data provides valuable references for subsequent gene function characterization and biosynthesis pathway optimization.

Bioengineering of long-chain polyunsaturated fatty acids in oilseed crops

Long-chain polyunsaturated fatty acids (LC-PUFAs), especially very long-chain polyunsaturated fatty acids (VLC-PUFAs), are highly beneficial to human health including brain development, cardiovascular health and the immune system. Plant-derived edible oils serve as crucial dietary sources of PUFAs for humans. However, oilseed crops such as soybean, peanut, rapeseed, sesame and flax, generally contain insufficient content of LC-PUFAs and do not naturally produce VLC-PUFAs. This review discusses PUFA biosynthesis, current efforts on LC-PUFA bioengineering in oilseed crops, comparing the advantages of different genetic engineering strategies and highlights the bottlenecks encountered in this field. Combination of high-efficient enzymes from various species has enabled the improvement of LC-PUFAs and slight production of VLC-PUFAs, though under risk of generational instability. These and future intelligently designed enzymes with multidisciplinary approaches in molecular biology, biochemistry and plant physiology can be crucial in developing oilseed crops that meet the growing demand for LC-PUFAs.

Identifying early predictive and diagnostic biomarkers and exploring metabolic pathways for sepsis after trauma based on an untargeted metabolomics approach

Systemic inflammatory response syndrome (SIRS) and organ dysfunction make it challenging to predict which major trauma patients are at risk of developing sepsis. Additionally, the unclear pathogenesis of sepsis after trauma contributes to its high morbidity and mortality. Identifying early predictive and diagnostic biomarkers, as well as exploring related metabolic pathways, is crucial for improving early prevention, diagnosis, and treatment. This study prospectively analyzed plasma samples from patients with severe trauma collected between March 2022 and November 2023. Trauma patients were divided into two groups based on whether they developed sepsis within two weeks: the TDDS group (trauma patients who did not develop sepsis) and the TDS group (trauma patients who did develop sepsis). Plasma samples from the TDS group were collected at the time of sepsis diagnosis (Sepsis group). Metabolite concentrations were measured using ultrahigh-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) through untargeted metabolomics. From the differential metabolites between the TDS and TDDS groups, we identified five significant metabolites (all area under the curve (AUC) ≥ 0.94) as early predictive biomarkers for sepsis after trauma: (1) docosatrienoic acid, (2) 7-alpha-carboxy-17-alpha-carboxyethylandrostan lactone phenyl ester, (3) sphingomyelin (SM) 8:1;2O/26:1, (4) N1-[1-(3-isopropenylphenyl)-1-methylethyl]-3-oxobutanamide, and (5) SM 34:2;2O. Furthermore, five significant metabolites (all AUC ≥ 0.85) were identified as early diagnostic biomarkers from the comparison between the TDS and TDDS groups: (1) lysophosphatidylcholine (LPC) O-22:1, (2) LPC O-22:0, (3) uric acid, (4) LPC O-24:2, and (5) LPC 22:0-SN1. 26 metabolites shared between two comparisons (TDS vs. TDDS and sepsis vs. TDS) were identified. Of which, 19 metabolites belong to lipid metabolism. The top three metabolic pathways related to sepsis after trauma under the impact of severe trauma were: (1) glycerophospholipid metabolism, (2) porphyrin metabolism, and (3) sphingolipid metabolism. The top three metabolic pathways related to sepsis after trauma under the impact of infection were: (1) caffeine metabolism, (2) biosynthesis of unsaturated fatty acids, and (3) steroid hormone biosynthesis. Our study identified early predictive and diagnostic biomarkers and explored metabolic pathways related to sepsis after trauma. These findings provide a foundation for future research on the onset and development of sepsis, facilitating its early prevention, diagnosis, and treatment based on specific metabolites and metabolic pathways.

Engineering Yarrowia lipolytica for sustainable Cis-13, 16-docosadienoic acid production

Cis-13, 16-docosadienoic acid (DDA) is an omega-6 polyunsaturated fatty acid with great potential for application in medicine and health. Using microbial cell factories for DDA production is considered a viable alternative to extracting DDA from plant seeds. In this study, using Yarrowia lipolytica Po1f (Δku70) as a chassis, firstly, the adaptation of three elongases in Po1f (Δku70) were explored. Secondly, the DDA biosynthetic pathway was redesigned, resulting in a DDA content of 0.046 % of total fatty acids (TFAs). Thirdly, through the "push-pull" strategy, the DDA content increased to 0.078 % of TFAs. By enhancing the supply of acetyl-CoA, the DDA production in the engineered strain YL-7 reached 0.391 % of the TFAs (3.19 mg/L). Through optimizing the fermentation conditions, the DDA titer of YL-7 reached 29.34 mg/L. This research achieves the sustainable biological production of DDA in Y. lipolytica.

Progress in understanding and improving oil content and quality in seeds

The world's population is projected to increase by two billion by 2050, resulting in food and energy insecurity. Oilseed crops have been identified as key to address these challenges: they produce and store lipids in the seeds as triacylglycerols that can serve as a source of food/feed, renewable fuels, and other industrially-relevant chemicals. Therefore, improving seed oil content and composition has generated immense interest. Research efforts aiming to unravel the regulatory pathways involved in fatty acid synthesis and to identify targets for metabolic engineering have made tremendous progress. This review provides a summary of the current knowledge of oil metabolism and discusses how photochemical activity and unconventional pathways can contribute to high carbon conversion efficiency in seeds. It also highlights the importance of 13C-metabolic flux analysis as a tool to gain insights on the pathways that regulate oil biosynthesis in seeds. Finally, a list of key genes and regulators that have been recently targeted to enhance seed oil production are reviewed and additional possible targets in the metabolic pathways are proposed to achieve desirable oil content and quality.

The core triacylglycerol toolbox in woody oil plants reveals targets for oil production bioengineering

Woody oil plants are the most productive oil-bearing species that produce seeds with high levels of valuable triacylglycerols (TAGs). TAGs and their derivatives are the raw materials for many macromolecular bio-based products, such as nylon precursors, and biomass-based diesel. Here, we identified 280 genes encoding seven distinct classes of enzymes (i.e., G3PAT, LPAAT, PAP, DGAT, PDCT, PDAT, and CPT) involved in TAGs-biosynthesis. Several multigene families are expanded by large-scale duplication events, such as G3PATs, and PAPs. RNA-seq was used to survey the expression profiles of these TAG pathway-related genes in different tissues or development, indicating functional redundancy for some duplicated genes originated from the large-scale duplication events, and neo-functionalization or sub-functionalization for some of them. Sixty-two genes showed strong, preferential expression during the period of rapid seed lipid synthesis, suggesting that their might represented the core TAG-toolbox. We also revealed for the first time that there is no PDCT pathway in Vernicia fordii and Xanthoceras sorbifolium. The identification of key genes involved in lipid biosynthesis will be the foundation to plan strategies to develop woody oil plant varieties with enhanced processing properties and high oil content.

Class A lysophosphatidic acid acyltransferase 2 from Camelina sativa promotes very long-chain fatty acids accumulation in phospholipid and triacylglycerol

Very long-chain fatty acids (VLCFAs) are important industrial raw materials and can be produced by genetically modified oil plants. For a long time, class A lysophosphatidic acid acyltransferase (LPAT) was considered unable to promote the accumulation of VLCFA in oil crops. The bottlenecks that the transgenic high VLCFA lines have an oil content penalty and the low amount of VLCFA in phosphatidylcholine remains intractable. In the present study, a class A LPAT2 from Camelina sativa (CsaLPAT2) promoting VLCFAs accumulation in phospholipid was found. Overexpression of CsaLPAT2 alone in Arabidopsis seeds significantly increased the VLCFA content in triacylglycerol, including C20:0, C20:2, C20:3, C22:0, and C22:1. The proportion of phosphatidic acid molecules containing VLCFAs in transgenic seeds reached up to 45%, which was 2.8-fold greater than that in wild type. The proportion of phosphatidylcholine and diacylglycerol molecules containing VLCFAs also increased significantly. Seed size in CsaLPAT2 transgenic lines showed a slight increase without an oil content penalty. The total phospholipid content in the seed of the CsaLPAT2 transgenic line was significantly increased. Furthermore, the function of class A LPAT in promoting the accumulation of VLCFAs is conserved in the representative oil crops of Brassicaceae, such as C. sativa, Arabidopsis thaliana, Brassica napus, Brassica rapa, and Brassica oleracea. The findings of this study provide a promising gene resource for the production of VLCFAs.

Combined dynamic transcriptomics and metabolomics analyses revealed the effects of trans-vp28 gene Synechocystis sp. PCC6803 on the hepatopancreas of Litopenaeus vannamei

Litopenaeus vannamei is the most important shrimp species throughout the world. However, diseases are increasing with the development of the industry, so enhancing the immunity of shrimp is of great significance. In this study, 1800 shrimp were divided into two groups randomly: the control group (N, feed with brine shrimp flake) and the experimental group (M, feed with mutant of Synechocystis sp. cells) (300 shrimp/group/replication) and each trial was conducted in triplicates. After immunization, sixty shrimp (with three replicates of twenty) were collected at 0 h in group N and 24, 72, and 144 h in group M, respectively, and the hepatopancreas were isolated for transcriptomic and metabolomic analysis. Transcriptome data revealed that compared with group N, genes related to antimicrobial peptides, cytoskeleton remodeling, detoxification, apoptosis, blood coagulation, immune defense, and antioxidant systems were differentially expressed in group M. In addition, combined transcriptomic and metabolomic analysis revealed that some immune-related differential genes or differential metabolites were consistently expressed in both omics. All the above results indicated that trans-vp28 gene Synechocystis sp. PCC6803 could improve the immunity of L. vannamei. This is the first report of the integration of dynamic transcriptomics combined with metabolomics to study the effect of trans-vp28 gene Synechocystis sp. PCC6803 in the hepatopancreas of L. vannamei and provided important information about the defense and immune mechanisms used by invertebrates against pathogens.

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.