Redirection of metabolic flux for high levels of omega‐7 monounsaturated fatty acid accumulation in camelina seeds

Seed oils enriched in omega‐7 monounsaturated fatty acids, including palmitoleic acid (16:1?9) and cis‐vaccenic acid (18:1?11), have nutraceutical and industrial value for polyethylene production and biofuels. Existing oilseed crops accumulate only small amounts (<2%) of these novel fatty acids in their seed oils. We demonstrate a strategy for enhanced production of omega‐7 monounsaturated fatty acids in camelina (Camelina sativa) and soybean (Glycine max) that is dependent on redirection of metabolic flux from the typical ?9 desaturation of stearoyl (18:0)‐acyl carrier protein (ACP) to ?9 desaturation of palmitoyl (16:0)‐acyl carrier protein (ACP) and coenzyme A (CoA). This was achieved by seed‐specific co‐expression of a mutant ?9‐acyl‐ACP and an acyl‐CoA desaturase with high specificity for 16:0‐ACP and CoA substrates, respectively. This strategy was most effective in camelina where seed oils with ~17% omega‐7 monounsaturated fatty acids were obtained. Further increases in omega‐7 fatty acid accumulation to 60–65% of the total fatty acids in camelina seeds were achieved by inclusion of seed‐specific suppression of 3‐keto‐acyl‐ACP synthase II and the FatB 16:0‐ACP thioesterase genes to increase substrate pool sizes of 16:0‐ACP for the ?9‐acyl‐ACP desaturase and by blocking C18 fatty acid elongation. Seeds from these lines also had total saturated fatty acids reduced to ~5% of the seed oil versus ~12% in seeds of nontransformed plants. Consistent with accumulation of triacylglycerol species with shorter fatty acid chain lengths and increased monounsaturation, seed oils from engineered lines had marked shifts in thermotropic properties that may be of value for biofuel applications.     

A novel <Emphasis Type="Italic">FAD2</Emphasis>-<Emphasis Type="Italic">1 A</Emphasis> allele in a soybean plant introduction offers an alternate means to produce soybean seed oil with 85% oleic acid content

The alteration of fatty acid profiles in soybean to improve soybean oil quality has been a long-time goal of soybean researchers. Soybean oil with elevated oleic acid is desirable because this monounsaturated fatty acid improves the nutrition and oxidative stability of soybean oil compared to other oils. In the lipid biosynthetic pathway, the enzyme fatty acid desaturase 2 (FAD2) is responsible for the conversion of oleic acid precursors to linoleic acid precursors in developing soybean seeds. Two genes encoding FAD2-1A and FAD2-1B were identified to be expressed specifically in seeds during embryogenesis and have been considered to hold an important role in controlling the seed oleic acid content. A total of 22 soybean plant introduction (PI) lines identified to have an elevated oleic acid content were characterized for sequence mutations in the FAD 2-1A and FAD2-1B genes. PI 603452 was found to contain a deletion of a nucleotide in the second exon of FAD2-1A. These important SNPs were used in developing molecular marker genotyping assays. The assays appear to be a reliable and accurate tool to identify the FAD 2-1A and FAD2-1B genotype of wild-type and mutant plants. PI 603452 was subsequently crossed with PI 283327, a soybean line that has a mutation in FAD2-1B. Interestingly, soybean lines carrying both homozygous insertion/deletion mutation (indel) FAD2-1A alleles and mutant FAD2-1B alleles have an average of 82–86% oleic acid content, compared to 20% in conventional soybean, and low levels of linoleic and linolenic acids. The newly identified indel mutation in the FAD2-1A gene offers a simple method for the development of high oleic acid commercial soybean varieties.     

Fatty Acid Diversity is Not Associated with Neutral Genetic Diversity in Native Populations of the Biodiesel Plant Jatropha curcas L.

Jatropha curcas L. (Euphorbiaceae) is a shrub native to Mexico and Central America, which produces seeds with a high oil content that can be converted to biodiesel. The genetic diversity of this plant has been widely studied, but it is not known whether the diversity of the seed oil chemical composition correlates with neutral genetic diversity. The total seed oil content, the diversity of profiles of fatty acids and phorbol esters were quantified, also, the genetic diversity obtained from simple sequence repeats was analyzed in native populations of J. curcas in Mexico. Using the fatty acids profiles, a discriminant analysis recognized three groups of individuals according to geographical origin. Bayesian assignment analysis revealed two genetic groups, while the genetic structure of the populations could not be explained by isolation‐by‐distance. Genetic and fatty acid profile data were not correlated based on Mantel test. Also, phorbol ester content and genetic diversity were not associated. Multiple linear regression analysis showed that total oil content was associated with altitude and seasonality of temperature. The content of unsaturated fatty acids was associated with altitude. Therefore, the cultivation planning of J. curcas should take into account chemical variation related to environmental factors.     

Reduced expression of FatA thioesterases in Arabidopsis affects the oil content and fatty acid composition of the seeds

Acyl–acyl carrier protein (ACP) thioesterases are enzymes that control the termination of intraplastidial fatty acid synthesis by hydrolyzing the acyl–ACP complexes. Among the different thioesterase gene families found in plants, the FatA-type fulfills a fundamental role in the export of the C18 fatty acid moieties that will be used to synthesize most plant glycerolipids. A reverse genomic approach has been used to study the FatA thioesterase in seed oil accumulation by screening different mutant collections of Arabidopsis thaliana for FatA knockouts. Two mutants were identified with T-DNA insertions in the promoter region of each of the two copies of FatA present in the Arabidopsis genome, from which a double FatA Arabidopsis mutant was made. The expression of both forms of FatA thioesterases was reduced in this double mutant (fata1 fata2), as was FatA activity. This decrease did not cause any evident morphological changes in the mutant plants, although the partial reduction of this activity affected the oil content and fatty acid composition of the Arabidopsis seeds. Thus, dry mutant seeds had less triacylglycerol content, while other neutral lipids like diacylglycerols were not affected. Furthermore, the metabolic flow of the different glycerolipid species into seed oil in the developing seeds was reduced at different stages of seed formation in the fata1 fata2 line. This diminished metabolic flow induced increases in the proportion of linolenic and erucic fatty acids in the seed oil, in a similar way as previously reported for the wri1 Arabidopsis mutant that accumulates oil poorly. The similarities between these two mutants and the origin of their phenotype are discussed in function of the results.     

Three‐dimensional genetic networks among seed oil‐related traits,metabolites and genes reveal the genetic foundations of oil synthesis in soybean

Although the biochemical and genetic basis of lipid metabolism is clear in Arabidopsis, there is limited information concerning the relevant genes in Glycine max (soybean). To address this issue, we constructed three‐dimensional genetic networks using six seed oil‐related traits, 52 lipid metabolism‐related metabolites and 54 294 SNPs in 286 soybean accessions in total. As a result, 284 and 279 candidate genes were found to be significantly associated with seed oil‐related traits and metabolites by phenotypic and metabolic genome‐wide association studies and multi‐omics analyses, respectively. Using minimax concave penalty (MCP) and smoothly clipped absolute deviation (SCAD) analyses, six seed oil‐related traits were found to be significantly related to 31 metabolites. Among the above candidate genes, 36 genes were found to be associated with oil synthesis (27 genes), amino acid synthesis (four genes) and the tricarboxylic acid (TCA) cycle (five genes), and four genes (GmFATB1a, GmPDAT, GmPLDα1 and GmDAGAT1) are already known to be related to oil synthesis. Using this information, 133 three‐dimensional genetic networks were constructed, 24 of which are known, e.g. pyruvate–GmPDAT–GmFATA2–oil content. Using these networks, GmPDAT, GmAGT and GmACP4 reveal the genetic relationships between pyruvate and the three major nutrients, and GmPDAT, GmZF351 and GmPgs1 reveal the genetic relationships between amino acids and seed oil content. In addition, GmCds1, along with average temperature in July and the rainfall from June to September, influence seed oil content across years. This study provides a new approach for the construction of three‐dimensional genetic networks and reveals new information for soybean seed oil improvement and the identification of gene function.     

Mapping QTL controlling fatty acid composition in a doubled haploid rapeseed population segregating for oil content

Increasing oil content and improving the fatty acid composition in the seed oil are important breeding goals for rapeseed (Brassica napus L.). The objective of the study was to investigate a possible relationship between fatty acid composition and oil content in an oilseed rape doubled haploid (DH) population. The DH population was derived from a cross between the German cultivar Sollux and the Chinese cultivar Gaoyou, both having a high erucic acid and a very high oil content. In total, 282 DH lines were evaluated in replicated field experiments in four environments, two each in Germany and in China. Fatty acid composition of the seed oil was analyzed by gas liquid chromatography and oil content was determined by NIRS. Quantitative trait loci (QTL) for fatty acid contents were mapped and their additive main effects were determined by a mixed model approach using the program QTLMapper. For all fatty acids large and highly significant genetic variations among the genotypes were observed. High heritabilities were determined for oil content and for all fatty acids (h ² = 0.82 to 0.94), except for stearic acid content (h ²= 0.38). Significant correlations were found between the contents of all individual fatty acids and oil content. Closest genetic correlations were found between oil content and the sum of polyunsaturated fatty acids (18:2 + 18:3; r _G = −0.46), the sum of monounsaturated fatty acids (18:1 + 20:1 + 22:1; r _G = 0.46) and palmitic acid (16:0; r _G = −0.34), respectively. Between one and eight QTL for the contents of the different fatty acids were detected. Together, their additive main effects explained between 28% and 65% of the genetic variance for the individual fatty acids. Ten QTL for fatty acid contents mapped within a distance of 0 to 10 cM to QTL for oil content, which were previously identified in this DH population. QTL mapped within this distance to each other are likely to be identical. The results indicate a close interrelationship between fatty acid composition and oil content, which should be considered when breeding for increased oil content or improved oil composition in rapeseed.     

Fatty acids of lipids from cultured soybean and rape cells

Lipids from cultured cells, leaves and seeds of two varieties each of soybean (Glycine max) and oil seed rape (Brassica napus) were separated into neutral lipids, glycolipids and phospholipids and their fatty acids were analysed. Usually, the fatty acid composition differed between corresponding fractions from cultured cells, leaves and seeds. Differences were least marked in (i) the phospholipids from cultured cells and leaves of soybean and (ii) the neutral lipids from cultured cells and seeds of rape. In the cultured cells, the fatty acid composition of the phospholipids differed from that of the glycolipids and neutral lipids, and fatty acids of chain length greater than C₁₈ comprised a large proportion of the fatty acids of the glycolipids.     

Vernonia DGATs increase accumulation of epoxy fatty acids in oil

Vernolic acid (cis‐12‐epoxy‐octadeca‐cis‐9‐enoic acid) is valuable as a renewable chemical feedstock. This fatty acid can accumulate to high levels in the seed oil of some plant species such as Vernonia galamensis and Stokesia laevis which are unsuitable for large‐scale production. A cost‐effective alternative for production of epoxy fatty acids is to genetically engineer its biosynthesis in commercial oilseeds. An epoxygenase cDNA (SlEPX) responsible for vernolic acid synthesis and two acyl‐CoA : diacylglycerol acyltransferase cDNAs (VgDGAT1 and VgDGAT2) catalysing triacylglycerol (TAG) formation were cloned from developing seeds of S. laevis and V. galamensis. Co‐expression of SlEPX and VgDGAT1 or VgDGAT2 greatly increases accumulation of vernolic acid both in petunia leaves and soybean somatic embryos. Seed‐specific expression of VgDGAT1 and VgDGAT2 in SlEPX mature soybean seeds results in vernolic acid levels of ～15% and 26%. Both DGAT1 and DGAT2 increase epoxy fatty acid accumulation with DGAT2 having much greater impact.     

An Arabinogalactan-protein from the Leaves of Nicotiana tabacum

The signals of fatty acids in the form of triglycerides were observed in the ¹³C NMR spectrum of an intact soybean seed. The major fatty acid component composition of triglycerides in a soybean seed, which includes linoleic acid, oleic acid and palmitic acid, was estimated by subtracting the spectra of authentic fatty acids from the spectrum of the intact soybean seeds. The fatty acid compositions of seeds of 11 Japanese soybean cultivars and 5 lines bred at the Asian Vegetable Research and Development Center (AVRDC) were estimated by this rapid (within lhr for one seed) and nondestructive analytical method.     

Reducing saturated fatty acids in Arabidopsis seeds by expression of a Caenorhabditis elegans 16:0–specific desaturase

Plant oilseeds are a major source of nutritional oils. Their fatty acid composition, especially the proportion of saturated and unsaturated fatty acids, has important effects on human health. Because intake of saturated fats is correlated with the incidence of cardiovascular disease and diabetes, a goal of metabolic engineering is to develop oils low in saturated fatty acids. Palmitic acid (16:0) is the most abundant saturated fatty acid in the seeds of many oilseed crops and in Arabidopsis thaliana. We expressed FAT–5, a membrane‐bound desaturase cloned from Caenorhabditis elegans, in Arabidopsis using a strong seed‐specific promoter. The FAT‐5 enzyme is highly specific to 16:0 as substrate, converting it to 16:1?9; expression of fat‐5 reduced the 16:0 content of the seed by two‐thirds. Decreased 16:0 and elevated 16:1 levels were evident both in the storage and membrane lipids of seeds. Regiochemical analysis of phosphatidylcholine showed that 16:1 was distributed at both positions on the glycerolipid backbone, unlike 16:0, which is predominately found at the sn‐1 position. Seeds from a plant line homozygous for FAT–5 expression were comparable to wild type with respect to seed set and germination, while oil content and weight were somewhat reduced. These experiments demonstrate that targeted heterologous expression of a desaturase in oilseeds can reduce the level of saturated fatty acids in the oil, significantly improving its nutritional value.     

Triacylglycerols in the seeds of northern Scots pine,Pinus sylvestris L., and Norway spruce,Picea abies (L.) Karst.

The geographical variation in the composition of triacylglycerols in seeds of Scots pine (Pinus sylvestris L.) and Norway spruce [Picea abies (L.) Karst.], grown in Finland, was analyzed. The total lipid content of pine seeds was slightly higher in the northernmost provenance (68 °50N), whereas the lipid content of spruce seeds was not affected systematically by the geographical origin of the seeds. The species studied differed in the proportions of fatty acids in their triacylglycerols, though the three most abundant components were the same, i.e. oleic acid (181 n9), linoleic acid (182n-6) and 5,9,12-octadecatrienoic acid (183 5c9c12c). These fatty acids corresponded to more than 80 mol% of the total fatty acids. According to mass spectrometric analyses, the triacylglycerols of both spruce and pine seeds consisted of the same molecular species with 52–56 acyl carbons, but in different proportions. Molecules with 54 acyl carbons represented approximately 75% of the pine and 85% of the spruce triacylglycerols, with the most abundant molecular species being 545, 546 and 547. Some minor differences in the fatty acid composition of triacylglycerols of pine seeds from different seed collecting areas were found: the proportion of linoleic acid slightly increased whereas that of 5,11,14-eicosatrienoic acid decreased towards the northern origins. Similar differences were not found in the proportions of fatty acids in spruce seed lots. Furthermore, the proportions of triacylglycerols in both pine and spruce seeds from northern and southern collecting areas were not significantly different. The higher content of total lipids in spruce seeds compared with pine seeds may be due to the structure of the seed coat, and the lipophilic layers inside it, acting as a barrier to imbibition.     

Changes in Oil Accumulation and Fatty Acid Composition of Soybean Seeds under Salt Stress in Response to Salicylic Acid and Jasmonic Acid

greenhouse experiment with factorial arrangement based on randomized complete block design with four replications was conducted in 2015 to evaluate the effects of salicylic acid (SA) (1 mM) and jasmonic acid (JA) (0.5 mM) on oil accumulation and fatty acid composition of soybean oil (Glycine max L.) under salt stress (Non-saline, 4, 7, and 10 dS/m NaCl). Oil percentage of soybean seeds declined, while oil content per seed enhanced with increasing seed filling duration. Foliar application of SA improved oil content per soybean seed at different stages of development under all salinity levels. Although JA treatment enhanced seed oil percentage, oil yield of these plants decreased as a result of reduction in seed yield per plant. In contrast, the highest oil yield was recorded for SA treated plants, due to higher seed yield. Salinity had no significant effects on percentage of palmitic acid and stearic acid, but treatment with JA significantly reduced stearic acid percentage. Oleic acid content of seeds increased, but percentages of linoleic acid, linolenic acid and unsaturation index (UI) of soybean oil decreased with increasing salinity. Foliar application of SA and JA improved oil quality of soybean seeds by reducing oleic acid and enhancing linoleic acid, linolenic acid contents and UI. Exogenous application of SA had the most beneficial effects on soybean seeds due to enhancing oil yield and quality under saline and non-saline conditions.     

Manipulation of amino acid composition in soybean seeds by the combination of deregulated tryptophan biosynthesis and storage protein deficiency

The ability of genetic manipulation to yield greatly increased concentrations of free amino acids (FAAs) in seeds of soybean was evaluated by introduction of a feedback-insensitive mutant enzyme of tryptophan (Trp) biosynthesis into two transformation-competent breeding lines deficient in major seed storage proteins. The storage protein-deficient lines exhibited increased accumulation of certain other seed proteins as well as of FAAs including arginine (Arg) and asparagine in mature seeds. Introduction of the gene for a feedback-insensitive mutant of an α subunit of rice anthranilate synthase (OASA1D) into the two high-FAA breeding lines by particle bombardment resulted in a >10-fold increase in the level of free Trp in mature seeds compared with that in nontransgenic seeds. The amount of free Trp in these transgenic seeds was similar to that in OASA1D transgenic seeds of the wild-type cultivar Jack. The composition of total amino acids in seeds of the high-FAA breeding lines remained largely unaffected by the expression of OASA1D with the exception of an increase in the total Trp content. Our results therefore indicate that the extra nitrogen resource originating from storage protein deficiency was used exclusively for the synthesis of inherent alternative nitrogen reservoirs such as free Arg and not for deregulated Trp biosynthesis conferred by OASA1D. The intrinsic null mutations responsible for storage protein deficiency and the OASA1D transgene affecting Trp content were thus successfully combined and showed additive effects on the amino acid composition of soybean seeds.     

Molecular basis of the high-palmitic acid trait in sunflower seed oil

Sunflower (Helianthus annuus L.) seed oil with high palmitic acid content has enhanced thermo-oxidative stability, which makes it well suited to high-temperature uses. CAS-5 is a sunflower mutant line that accumulates over 25 % palmitic acid in its seed oil, compared to 5–8 % in conventional cultivars. The objective of this study was to investigate the molecular basis of the high-palmitic acid trait in CAS-5 through both candidate gene and QTL mapping approaches. An F₂ population derived from the cross between CAS-5 and the conventional line HA-89 was developed. A 3-ketoacyl-ACP synthase II (KASII) locus on a telomeric region of linkage group (LG) 9 of the sunflower genetic map was found to co-segregate with palmitic acid content in this population. The KASII locus explained the vast majority of the phenotypic variation (98 %) of the trait. Two minor QTL affecting palmitic acid content were also found on the lower half of LG 9 and on LG 17. Additionally, QTL associated with other major fatty acids (stearic, oleic, and linoleic acid) were identified on LG 1, 6, and 10. This result may reflect untapped genetic variation that could exist among sunflower cultivars for genes determining fatty acid composition. In addition to demonstrating the major role of a KASII locus in the accumulation of high levels of palmitic acid in CAS-5 seeds, this study stressed the importance of characterizing genes with minor effects on fatty acid profile in order to establish optimal breeding strategies for modifying fatty acid composition in sunflower seed oil.     

Modification of seed oil content and acyl composition in the brassicaceae by expression of a yeast sn-2 acyltransferase gene.

A putative yeast sn-2 acyltransferase gene (SLC1-1), reportedly a variant acyltransferase that suppresses a genetic defect in sphingolipid long-chain base biosynthesis, has been expressed in a yeast SLC deletion strain. The SLC1-1 gene product was shown in vitro to encode an sn-2 acyltransferase capable of acylating sn-1 oleoyl-lysophosphatidic acid, using a range of acyl-CoA thioesters, including 18:1-, 22:1-, and 24:0-CoAs. The SLC1-1 gene was introduced into Arabidopsis and a high erucic acid-containing Brassica napus cv Hero under the control of a constitutive (tandem cauliflower mosaic virus 35S) promoter. The resulting transgenic plants showed substantial increases of 8 to 48% in seed oil content (expressed on the basis of seed dry weight) and increases in both overall proportions and amounts of very-long-chain fatty acids in seed triacylglycerols (TAGs). Furthermore, the proportion of very-long-chain fatty acids found at the sn-2 position of TAGs was increased, and homogenates prepared from developing seeds of transformed plants exhibited elevated lysophosphatidic acid acyltransferase (EC 2.3.1.51) activity. Thus, the yeast sn-2 acyltransferase has been shown to encode a protein that can exhibit lysophosphatidic acid acyltransferase activity and that can be used to change total fatty acid content and composition as well as to alter the stereospecific acyl distribution of fatty acids in seed TAGs.     

Changes in the composition of winter rape oil during seed maturation

The course of biosynthesis of fatty acids in the seeds of winter rape (Brassica napus L. ssp.oleifera, f.biennis cv. T?ebí?ská) was investigated. After the termination of flowering seed samples were taken at five intervals, the seeds were divided into 4 fractions according to size, and their weight, water content, oil content and fatty acid composition were determined. The oil content was found to increase in all size categories with time, with the exception of a minute drop when complete maturity is reached. Larger seeds contained more oil. The fatty acid composition changes with time in the individual size fractions almost continuously. The same holds for differences between seed sizes of the same sample. The main change in oil composition consists in the decrease of C₁₈ acids in favour of C₂₂ acids. Greatest decrements during maturation were found with oleic acid, less with linoleic acid. In absolute amounts the quantity of all synthesized acids rises, the greatest rise being observed with C₂₂ acids (i.e. predominantly erucic acid). It follows from the mean rates of synthesis of the individual groups (C₁₆, C₁₈, C₂₀, C₂₂) of fatty acids that the fraction of C₂₂ rate of synthesis increases, while that of the C₁₈ acids decreases with the same speed. The results indicate that the fatty acid synthesis is most intense during the second half of seed maturation, the main role being played by accelerating the synthesis of higher acids, especially of erucic acid.     

KAS IV: a 3-ketoacyl-ACP synthase from Cuphea sp . is a medium chain specific condensing enzyme

cDNA clones encoding a novel 3-ketoacyl-ACP synthase (KAS) have been isolated from Cuphea . The amino acid sequence of this enzyme is different from the previously characterized classes of KASs, designated KAS I and III, and similar to those designated as KAS II. To define the acyl chain specificity of this enzyme, we generated transgenic Brassica plants over-expressing the cDNA encoded protein in a seed specific manner. Expression of this enzyme in transgenic Brassica seeds which normally do not produce medium chain fatty acids does not result in any detectable modification of the fatty acid profile. However, co-expression of the Cuphea KAS with medium chain specific thioesterases, capable of production of either 12:0 or 8:0/10:0 fatty acids in seed oil, strongly enhances the levels of these medium chain fatty acids as compared with seed oil of plants expressing the thioesterases alone. By contrast, co-expression of the Cuphea KAS along with an 18:0/18:1-ACP thioesterase does not result in any detectable modification of the fatty acids. These data indicate that the Cuphea KAS reported here has a different acyl-chain specificity to the previously characterized KAS I, II and III. Therefore, we designate this enzyme KAS IV, a medium chain specific condensing enzyme.     

Bioinformatics and Functional Analysis of High Oleic Acid-Related Gene Gm<i>SAM22</i> in Soybean [<i>Glycine max</i> (L.) Merr.]

High yield, high quality, stable yield, adaptability to growth period, and modern mechanization are the basic requirements for crops in the 21st century. Soybean oleic acid is a natural unsaturated fatty acid with strong antioxidant properties and stability. Known as a safe fatty acid, it has the ability to successfully prevent cardiovascular and cerebrovascular disorders. Improving the fatty acid composition of soybean seeds, can not only speed up the breeding process of high-quality high-oil and high-oleic soybeans, but also have important significance in human health, and provide the possibility for the development of soybean oil as a new energy source. Hence, the aim of this study was to analyze the high oleic acid elated gene GmSAM22 in soybean. In this research the soybean oleic acid-related gene GmSAM22 was screened out by Genome-wide association analysis, a 662 bp fragment was acquired by specific PCR amplification, and the pMD18T cloning vector was linked by the use of a seamless cloning technique. Bioinformatics analysis of the signal peptide prediction, subcellular localization, protein hydrophobicity, transmembrane region analysis, a phosphorylation site, protein secondary and tertiary structure and protein interaction analysis of the protein encoded by the SAM22 gene was carried out. The plasmid of the gene editing vector is pBK041. The overexpression vector was transformed from pCAMBIA3301 as the base vector, and overexpression vector were designed. Positive plants were obtained by genetic transformation by the pollen tube channel method. Fluorescence quantitative PCR was performed on the T₂ generation plants to detect the relative expression levels in different tissues. Southern Blot was used to detect the presence of hybridization signal. Screening genes BAR, 35S, and NOS in plants were identified by conventional PCR. 10 seeds with high and low oleic acid content were chosen for quantitative PCR identification, and finally, the concentration and morphology of soybean fatty acids were identified by near-far infrared spectroscopy. On 10 seeds with an upper and lower oleic acid content, a quantitative fluorescence analysis was done. In Southern blot hybridization, the SAM22 gene was integrated into the recipient soybean plant in hands of a sole copy. Fluorescence quantitative PCR appeared that the average relative expression of the SAM22 gene in roots, stems, leaves, and seeds was 1.70, 1.67, 3.83, and 4.41, respectively. Positive expression seeds had a 4.77% increase in oleic acid content. The level of oleic acid in the altered seeds was reduced by 4.13% when compared to CK, and it was discovered that the GmSAM22 gene could be a regulatory and secondary gene that promotes the conversion of stearic acid to oleic acid in soybean. There has not been a discussion of gene cloning or functional verification. The cloning and genetic transformation of the soybean SAM22 gene can effectively increase the content of oleic acid, which lays a foundation for the study of soybean with high oleic acid.     

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

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