Genetic control of chlorophyll biosynthesis by the plastome in some Oenothera species (subgenus Munzia)

Reciprocal differences in the rates of chlorophyll (Chl) formation during early stages of greening are observed in hybrid seedlings with identical genomes derived from reciprocal crosses between Oenothera berteriana (=villaricae) and Oe. odorata (=picensis), subgenus Munzia. In the presence of levulinic acid (LA), a competitive inhibitor of 5-aminolevulinic acid (ALA) dehydratase, ALA accumulated in the cotyledons and chlorophyll production was reduced in a stoichometric ratio. Accumulation of both Chl in untreated tissue and of ALA in seedlings incubated with LA is much more rapid in cotyledons with berteriana plastids than in those with odorata plastids. No difference was found between the inhibitor constants for LA of ALA dehydratase extracted from seedlings with either berteriana or odorata plastids. ALA formation is not limited by the availability of possible precursors. ALA dehydratase and the porphobilinogenase complex (PBGase) are present in abundance and in equal amounts in cotyledons with either berteriana or odorata plastids. It is concluded that the different capacities of the ALA synthesizing system fully account for the different rates of Chl formation in the seedlings with identical genomes and different plastid types.Abbreviations Chl chlorophyll - ALA 5-aminolevnlinic acid - ALAD 5-aminolevulinic acid dehydratase - LA levulinic acid - PBG porphobilinogen - PBGase porphobilinogenase - Oe Oenothera - bert berteriana - od odorata - Pl plastids     

Production of 5-aminolevulinic acid by photosynthetic bacteria

Extracellular formation of 5-aminolevulinic acid (ALA) by adding levulinic acid (LA), an inhibitor of ALA dehydratase, was examined in the anaerobic-light culture of Rhodobacter sphaeroides. The addition of LA (10–25 mmol/l) during the middle log phase retarded the growth and accelerated the extracellular formation of ALA, while over 50 mmol/l completely suppressed both growth and formation.The formation of ALA was closely related to intracellular ALA synthetase activity. Light intensity was also an important factor for enhancing ALA formation. The optimal condition, addition of 15 mmol/l of LA during the middle log phase with 3 klx illumination, resulted in ALA formation of 0.26 mol/l. In addition, supplementation with glycine (30 mmol/l) and succinate (30 mmol/l), precursors of ALA biosynthesis, enhanced ALA formation up to ca. 2 mmol/l.     

Chlorophyll formation and glycine metabolism in laevulinic acid treated barley leaves

Laevulinic acid (LA) inhibited chlorophyll formation and δ-aminolaevulinic acid (ALA) accumulation in dark-grown barley leaves. Mole ratios (ALA: chlorophyll × 8) indicate that LA decreased ALA production by about 30%. The turnover of glycine-[¹⁴C] in 7-day-old leaves treated with LA was 70% slower than in control tissue and this resulted in an increase in endogenous glycine. Total amino acid also increased in LA treated leaves. The data indicate that any contribution made by glycine to ALA synthesis in LA-treated barley leaves would be significantly restricted.     

Production of a herbicide, 5-aminolevulinic acid,by Rhodobacter sphaeroides using the effluent of swine waste from an anaerobic digestor

Summary For the production of a herbicide, 5-amino-levulinic acid (ALA), from anaerobic digestion liquor, the utilization of the photosynthetic bacterium, Rhodobacter sphaeroides was examined. This bacterium could produce ALA extracelularly from this liquor with the addition of levulinic acid (LA), an inhibitor of ALA dehydratase (ALAD), and glycine, a precursor of ALA biosynthesis in the Shemin pathway. Succinate (another precursor) addition was unnecessary for ALA production. When repeated additions of LA were made together with glycine ALA production was significantly enhanced. However, above three additions of LA, ALA production was not further enhanced. The maximum value of ALA production attained was 4.2 mM (0.63 g/ 1), which was over double that of other ALA producers such as Chlorella vulgaris. Propionic acid was predominantly utilized compared with other lower fatty acids, suggesting that this might be converted to ALA via succinyl-coenzyme A (CoA) in the methylmalonyl-CoA pathway.Offprint requests to: Y. Nishizawa     

Inhibition of 5-aminolevulinic acid (ALA) dehydratase by undissociated levulinic acid during ALA extracellular formation by Rhodobacter sphaeroides

The inhibition of ALA dehydratase by levulinic acid during ALA extracellular formation of Rhodobacter sphaeroides correlated with the concentration of undissociated form of levulinic acid irrespective of culture pH. The inhibition constant, Ki, of intracellular ALA dehydratase by Dixon plots was 2.95 μM. Undissociated levulinic acid therefore functions as an inhibitor of ALA dehydratase. This revised version was published online in November 2006 with corrections to the Cover Date.     

Utilization of volatile fatty acids from the anaerobic digestion liquor of sewage sludge for 5-aminolevulinic acid production by photosynthetic bacteria

Using volatile fatty acids (VFA) from the anaerobic digestion liquor of sewage sludge, up to 9.2 mm 5-aminolevulinic acid (ALA) could be produced by Rhodobacter sphaeroides under anaerobic-light (5 kLux) conditions with repeated addition of levulinic acid (LA) and glycine and using a large inoculum (approx. 2 g/l of cells, initially from glutamate/malate medium). As the VFA medium also contained organic nitrogen sources such as glutamic acid, the cells were later grown up to about 2 g/l in the VFA medium instead of the glutamate/malate medium. ALA production was then again promoted by adding LA and glycine. Using this improved method, up to 9.3 mm ALA was produced by feeding propionate and acetate together with LA and glycine, indicating that VFA medium formed from sewage sludge could be useful for ALA production.     

Catabolism of [1-C]levulinic Acid by etiolated and greening barley leaves

Levulinic acid (LA), a competitive inhibitor of δ-aminolevulinic acid (ALA) dehydratase (EC 4.2.1.24), has been used extensively in the study of ALA formation during greening. When [1-¹⁴C]LA is administered to etiolated barley (Hordeum vulgare L. var. Larker) shoots in darkness, ¹⁴CO₂ is evolved. This process is accelerated when such tissues are incubated with 2 millimolar ALA or placed under continuous illumination. Label from the C-1 of LA becomes incorporated into organic acids, amino acids, sugars, lipids, and proteins during a 4-hour incubation in darkness or in the light. This metabolism is discussed in relation to the use of LA as a tool in the study of chlorophyll synthesis in higher plants.     

Linoleic and α-linolenic acid as precursor and inhibitor for the synthesis of long-chain polyunsaturated fatty acids in liver and brain of growing pigs

Studies suggested that in human adults, linoleic acid (LA) inhibits the biosynthesis of n-3 long-chain polyunsaturated fatty acids (LC-PUFA), but their effects in growing subjects are largely unknown. We used growing pigs as a model to investigate whether high LA intake affects the conversion of n-3 LC-PUFA by determining fatty acid composition and mRNA levels of Δ5- and Δ6 desaturase and elongase 2 and -5 in liver and brain. In a 2 × 2 factorial arrangement, 32 gilts from eight litters were assigned to one of the four dietary treatments, varying in LA and α-linolenic acid (ALA) intakes. Low ALA and LA intakes were 0.15 and 1.31, and high ALA and LA intakes were 1.48 and 2.65 g/kg BW0.75 per day, respectively. LA intake increased arachidonic acid (ARA) in liver. ALA intake increased eicosapentaenoic acid (EPA) concentrations, but decreased docosahexaenoic acid (DHA) (all P < 0.01) in liver. Competition between the n-3 and n-6 LC-PUFA biosynthetic pathways was evidenced by reductions of ARA (>40%) at high ALA intakes. Concentration of EPA (>35%) and DHA (>20%) was decreased by high LA intake (all P < 0.001). Liver mRNA levels of Δ5- and Δ6 desaturase were increased by LA, and that of elongase 2 by both ALA and LA intakes. In contrast, brain DHA was virtually unaffected by dietary LA and ALA. Generally, dietary LA inhibited the biosynthesis of n-3 LC-PUFA in liver. ALA strongly affects the conversion of both hepatic n-3 and n-6 LC-PUFA. DHA levels in brain were irresponsive to these diets. Apart from Δ6 desaturase, elongase 2 may be a rate-limiting enzyme in the formation of DHA.     

Metabolism of linoleic and α-linolenic acids in cultured cardiomyocytes: Effect of different N-6 and N-3 fatty acid supplementation

The metabolites of linoleic (LA) and -linolenic (ALA) acids are involved in coronary heart disease. Both n-6 and n-3 essential fatty acids (EFAs) are likely to be important in prevention of atherosclerosis since the common risk factors are associated with their reduced 6-desaturation. We previously demonstrated the ability of heart tissue to desaturate LA. In this study we examined the ability of cultured cardiomyocytes to metabolize both LA and ALA in vivo, in the absence and in the presence of gamma linolenic acid (GLA), eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) alone or combined together. In control conditions, about 25% of LA and about 90% of ALA were converted in PUFAs. GLA supplementation had no influence on LA conversion to more unsaturated fatty acids, while the addition of n-3 fatty acids, alone or combined together, significantly decreased the formation of interconversion products from LA. Using the combination of n-6 and n-3 PUFAs, GLA seemed to counterbalance partially the inhibitory effect of EPA and DHA on LA desaturation/elongation. The conversion of ALA to more unsaturated metabolites was greatly affected by GLA supplementation. Each supplemented fatty acid was incorporated to a significant extent into cardiomyocyte lipids, as revealed by gas chromatographic analysis. The n-6/n-3 fatty acid ratio was greatly influenced by the different supplementations; the ratio in GLA+EPA+DHA supplemented cardiomyocytes was the most similar to that recorded in control cardiomyocytes. Since important risk factors for coronary disease may be associated with reduced 6-desaturation of the parent EFAs, administration of n-6 or n-3 EFA metabolites alone could cause undesirable effects. Since they appear to have different and synergistic roles, only combined treatment with both n-6 and n-3 metabolites is likely to achieve optimum results.     

Omega-6 and omega-3 fatty acids metabolism pathways in the body of pigs fed diets with different sources of fatty acids

This study was carried out on 24 gilts (♀ Polish Large White × ♂ Danish Landrace) grown with body weight (BW) of 60 to 105 kg. The pigs were fed diets designed on the basis of a standard diet (appropriate for age and BW of pigs) where a part of the energy content was replaced by different fat supplements: linseed oil in Diet L, rapeseed oil in Diet R and fish oil in Diet F (6 gilts per dietary treatment). The fat supplements were sources of specific fatty acids (FA): in Diet L α-linolenic acid (C18:3 n?3, ALA); in Diet R linoleic acid (C18:2 n?6, LA) and in Diet F eicosapentaenoic acid (C20:5 n?3, EPA), docosapentaenoic acid (C22:5 n?3, DPA) and docosahexaenoic acid (C22:6 n?3, DHA). The protein, fat and total FA contents in the body did not differ among groups of pigs. The enhanced total intake of LA and ALA by pigs caused an increased deposition of these FA in the body (p < 0.01) and an increased potential body pool of these acids for further metabolism/conversions. The conversion efficiency of LA and ALA from the feed to the pig’s body differed among groups (p < 0.01) and ranged from 64.4% to 67.2% and from 69.4% to 81.7%, respectively. In Groups L and R, the level of de novo synthesis of long-chain polyunsaturated FA was higher than in Group F. From the results, it can be concluded that the efficiency of deposition is greater for omega-3 FA than for omega-6 FA and depends on their dietary amount. The level of LA and ALA intake influences not only their deposition in the body but also the end products of the omega-3 and omega-6 pathways.     

Specific inhibition of tetrapyrrole biosynthesis by 3-amino 2,3-dihydrobenzoic acid (gabaculin) in the cyanobacteriumSynechococcus 6301

Gabaculin (3-amino 2,3-dihydrobenzoic acid) inhibited the growth of cyanobacteria but not of other prokaryotes. Exposure of growing cultures ofSynechococcus 6301 to 50 M gabaculin resulted in an immediate and complete inhibition of the synthesis of chlorophylla and phycocyanin. With 8 M gabaculin, tetrapyrrole synthesis was suppressed for approximately 10 h and then resumed at a lower rate than in untreated organisms. The effect of 50 M gabaculin was reversed by transferring organisms to inhibitor-free medium; chlorophylla synthesis began within 5 h and exponential growth was re-established after about 25 h. Compared with 4,6-dioxoheptanoic acid (DA) and laevulinic acid (LA), gabaculin was a much more potent inhibitor of tetrapyrrole synthesis inSynechococcus 6301. The catalytic activity of -aminolaevulinic acid (ALA) dehydratase in vitro was inhibited by DA and LA but not by 1 mM gabaculin. However, the specific activity of the dehydratase was much lower in organisms exposed to the inhibitor for 36 h. Growing cultures and cell suspensions ofSynechococcus 6301 exposed to DA excreted appreciable quantities of ALA. In contrast, relatively small amounts of ALA accumulated in the presence of gabaculin alone and this inhibitor blocked the excretion of ALA caused by DA. This suggests that the primary effect of gabaculin is the specific inhibition of the C₅ pathway for the biosynthesis of ALA.Abbreviations ALA -aminolaevulinic acid - DA 4,6-dioxoheptanoic acid - LA laevulinic acid - GABA -aminobutyric acid     

Heterologous expression of two <Emphasis Type="Italic">Glycine max</Emphasis> ω-3 fatty acid desaturases in <Emphasis Type="Italic">Saccharomyces cerevisiae</Emphasis>

α-Linolenic acid (ALA, C 18:3^Δ9,12,15) has many important biological functions. ω-3 Fatty acid desaturase (FAD3), existing in cytosolic and plastidic compartments of higher plants, catalyzes linoleic acid (LA) desaturation to produce ALA. GmFAD3A-2 and GmFAD3C genes encoding cytosolic FAD3 from Qihuang 29 soybean were cloned and inserted into p416 vector and expressed in K601 yeast strain. Gas chromatography showed that the transformed yeast strains could produce ALA. The ALA accumulation levels for the strains transformed with GmFAD3A-2 or GmFAD3C genes were 0.77 ± 0.1 and 4.13 ± 0.4% of total fatty acids, respectively, while, as compared with that of the control, the contents of LA decreased from 14.34 ± 0.8 to 10.93 ± 0.0 and 7.85 ± 0.1%, respectively, implying that the GmFAD3C enzyme is more vigorous or stable, than GmFAD3A-2. Published in Russian in Fiziologiya Rastenii, 2009, Vol. 56, No. 4, pp. 629–634. This text was submitted by the authors in English.     

Quantitative relationships between ingested and intestinal flows of linoleic and alpha-linolenic acids,body weight and milk performance in mid-lactation dairy cows

Linoleic acid (LA) and alpha-linolenic acid (ALA) are essential fatty acids found in variable quantities in ruminant feedstuffs. Revision of French feed unit systems in 2018 has proposed the reassessment of energy requirements through a between-experiment approach expressing metabolisable energy supply as a function of the energy expenditures for maintenance and production, with these expenditures that reflect homeorhetic regulations. Based on the same approach, LA and ALA intake can be related to animal characteristics (i.e., BW) reflecting maintenance expenditures and secretion characteristics (i.e., milk yield, milk fat content and contents of LA and ALA in milk fat). Therefore, the objective of this work was to analyse the between-experiment relationships between ingested, duodenal, or absorbed flows of LA and ALA, BW and milk LA and ALA secretion by meta-analysis in mid-lactation dairy cows. These relationships were analysed using LA and ALA subsets of 96 and 99 experiments, respectively. Between-experiment regressions of daily flows of ingested, duodenal or absorbed LA and ALA on BW and milk LA and ALA flows were studied, with statistical unit defined as the mean of within-experiment treatments. For LA, the BW-associated coefficient was 0.019 (±0.0034) g absorbed LA/d per kg BW and milk LA secretion-associated coefficient was 0.70 (±0.081) g absorbed LA/g of LA secreted into milk. For ALA, the BW-associated coefficient was 0.0058 (±0.00093) g absorbed ALA/d per kg BW and milk ALA secretion-associated coefficient was 0.57 (±0.097) g absorbed ALA/g of ALA secreted into milk. When coding the diets as either control or milk fat depression diets, the BW-associated coefficient for LA was 0.017 (±0.0032) g absorbed LA/d per kg BW for both diets. For milk fat depression diets, milk LA secretion-associated coefficient was 1.02 (±0.119) g absorbed LA/g of LA secreted into milk, whereas it was 0.70 (±0.075) g absorbed LA/g of LA secreted into milk for control diets. Significant BW and milk performance coefficients were obtained in all LA and ALA equations, allowing the calculation of ingested and intestinal flows of LA and ALA based on measured BW, milk fat yield and milk fat content of LA and ALA. The relationships between ingested and intestinal flows of LA and ALA, BW and milk performance obtained in the present work could be integrated into renewed feed unit systems for energy and protein in dairy cows.     

Effects of Light on Chlorophyll Formation in Cultured Tobacco Cells II. Blue Light Effect on 5-Aminolevulinic Acid Formation

5-Aminolevulinic acid (ALA) accumulation in dark-grown tobaccocallus cells in the presence of levulinic acid (LA) was followedunder blue or red light or in continuous darkness. Significantformation of ALA continued in the dark. The protochlorophyll-(ide) (Pchl) content of dark-incubated cells remained low becauseof its turnover. We inferred that the feedback inhibition ofALA synthesis by Pchl would not occur in darkincubated calluscells. ALA formation was enhanced by blue light, and this effectreached saturation at an intensity of about 800 mW.m^–2.Neither weak nor strong red light affected ALA formation. Fullenhancement of ALA formation by blue light was attained afterfairly long continuous illumination of the callus cells. Thisblue lightenhanced activity of ALA synthesis declined very slowlyduring the subsequent dark incubation. The blue light enhancement of ALA formation was observed incallus cells supplied with sucrose over a wide range of concentrations.Pchl regeneration in carbon-starved callus cells, supplied withglutamate at various concentrations, was also markedly enhancedby blue light. Respiration of the callus cells was not enhancedby blue light. A possible role of blue light in regulating ALAformation in callus cells is discussed. ¹Dedicated to the late Professor Joji Ashida. (Received September 3, 1982; Accepted April 5, 1983)     

Functional characterization of two microsomal fatty acid desaturases from Jatropha curcas L.

Linoleic acid (LA, C18:2) and α-linolenic acid (ALA, C18:3) are polyunsaturated fatty acids (PUFAs) and major storage compounds in plant seed oils. Microsomal ω-6 and ω-3 fatty acid (FA) desaturases catalyze the synthesis of seed oil LA and ALA, respectively. Jatropha curcas L. seed oils contain large proportions of LA, but very little ALA. In this study, two microsomal desaturase genes, named JcFAD2 and JcFAD3, were isolated from J. curcas. Both deduced amino acid sequences possessed eight histidines shown to be essential for desaturases activity, and contained motif in the C-terminal for endoplasmic reticulum localization. Heterologous expression in Saccharomyces cerevisiae and Arabidopsis thaliana confirmed that the isolated JcFAD2 and JcFAD3 proteins could catalyze LA and ALA synthesis, respectively. The results indicate that JcFAD2 and JcFAD3 are functional in controlling PUFA contents of seed oils and could be exploited in the genetic engineering of J. curcas, and potentially other plants.     

Dietary linoleic acid has no effect on arachidonic acid,but increases n-6 eicosadienoic acid,and lowers dihomo-γ-linolenic and eicosapentaenoic acid in plasma of adult men

High intakes of linoleic acid (LA,18:2n-6) have raised concern due to possible increase in arachidonic acid (ARA, 20:4n-6) synthesis, and inhibition of alpha linolenic acid (ALA, 18:3n-3) desaturation to eicosapentaenoic (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3). In healthy men, 10.5% energy compared to 3.8% energy LA with 1% energy ALA increased plasma phospholipid LA and 20:2n-6, the elongation product of LA, and decreased EPA, with no change in ARA. However, LA was inversely related to ARA at both 10.5% energy and 3.8% energy LA, (r=?0.761, r=?0.817, p<0.001, respectively). A two-fold variability in ARA among individuals was not explained by the dietary LA, ARA, ALA, or fish intake. Our results confirm LA requirements for ARA synthesis is low, <3.8% energy, and they suggest current LA intakes saturate Δ-6 desaturation and adversely affect n-3 fatty acid metabolism. Factors other than n-6 fatty acid intake are important modifiers of plasma ARA.     

Effects of artificial ultraviolet-B radiation on growth and fatty acid composition of duckweed (Lemna minor)

1. Duckweed (Lemna minor), collected either in summer or early fall was exposed under laboratory conditions to control (photosynthetically active and UV‐A radiation) or experimental (control plus UV‐B radiation) conditions. 2. Growth and survival were determined by counting the number of green, and brown/white fronds following 1–5 or 11 days of irradiation. Growth of duckweed was impaired by exposure to UV‐B radiation in the fall experiment but not in the summer. 3. Fatty acid compositions were analysed following 5 or 11 days of irradiation and a recovery period of 0, 5, 29 or 40 h. Concentrations of the major fatty acids, palmitic, linoleic (LA) and α‐linolenic (ALA) acids were similar in the summer and fall duckweed collections, but the summer samples had higher concentrations of the desaturation products of LA and ALA. 4. UV‐B exposure had small, but significant, and contrasting effects on duckweed fatty acid concentrations. In the summer experiment, duckweed exposed to UV‐B had slightly lower concentrations of major fatty acids than control duckweed, while the reverse was true in the fall experiments. 5. These minor effects of UV‐B on concentrations of LA and ALA would be unlikely to have a major impact on the supply of these essential fatty acids from duckweed to freshwater food webs.     

Isolation of a novel C18-Δ9 polyunsaturated fatty acid specific elongase gene from DHA-producing <Emphasis Type="Italic">Isochrysis galbana</Emphasis> H29 and its use for the reconstitution of the alternative Δ8 pathway in <Emphasis Type="Italic">Saccharomyces cerevisiae</Emphasis>

A novel gene (IgASE2) encoding a C18-Δ9 polyunsaturated fatty acids specific (C18-Δ9-PUFAs-specific) elongase was isolated and characterized from DHA-rich microalga, Isochrysis galbana H29. The IgASE2 gene was 1,653 bp in length, contained a 786 bp ORF encoding a protein of 261 amino acids that shared 87% identity with Δ9 elongase, IgASE1, and possessed a 44 bp 5′-untranslated region (5′-UTR) and a 823 bp 3′-untranslated region (3′-UTR). IgASE2, by its heterologous expression in Saccharomyces cerevisiae, elongated linoleic acid (LA, 18:2n−6) and α-linolenic (ALA, 18:3n−3) to eicosadienoic acid (EDA, 20:2n−6) and eicosatrienoic acid (ETrA, 20:3n−3), respectively. The conversions of LA to EDA and ALA to ETrA were 57.6 and 56.1%, respectively. Co-expression of this elongase with Δ8 desaturase required for the synthesis of C20-polyunsaturated fatty acids resulted in the accumulation of dihomo-γ-linolenic acid (20:3n−6) from LA and eicosatetraenoic acid (20:4n−6) from ALA. These results demonstrated that IgASE2 exhibited C18-Δ9-PUFAs-specific elongase activity and the alternative Δ8 pathway was reconstituted.     

光合细菌嗜酸柏拉红菌5-氨基乙酰丙酸合成酶基因的克隆与原核表达

5-氨基乙酰丙酸(ALA)可作为除草剂、杀虫剂和植物生长调节剂在农业上应用,但由于其成本较高而限制了它的大面积使用。利用常规基因工程操作方法结合载体介导PCR法(Vecterette PCR)克隆了嗜酸柏拉红菌(Rhodoblastus acidophilus)的5-氨基乙酰丙酸合成酶(ALAS)基因。并将编码ALAS的基因插入到原核表达载体pQE30中,在大肠杆菌不同菌株(E.coli JM109、M15及BL21(DE3))中进行诱导表达。对产物进行SDS-PAGE分析表明,ALAS基因已在细菌中成功表达。使用Ni-NTA亲和层析法对表达的ALAS进行分离、纯化,得到大小约为44kD的ALAS蛋白。通过优化工程菌株的培养条件,建立了发酵生产ALA的方法,其胞外分泌ALA产量达5.379g/L,ALAS酶活力高达333U/min.mg。这是目前国内外利用生物法生产ALA产量最高的报道,为ALA的产业化应用打下了良好的基础。     

Histone acetyltransferase general control non‐repressed protein 5 (GCN5) affects the fatty acid composition of Arabidopsis thaliana seeds by acetylating fatty acid desaturase3 (FAD3)

Seed oils are important natural resources used in the processing and preparation of food. Histone modifications represent key epigenetic mechanisms that regulate gene expression, plant growth and development. However, histone modification events during fatty acid (FA) biosynthesis are not well understood. Here, we demonstrate that a mutation of the histone acetyltransferase GCN5 can decrease the ratio of α‐linolenic acid (ALA) to linoleic acid (LA) in seed oil. Using RNA‐Seq and ChIP assays, we identified FAD3, LACS2, LPP3 and PLAIIIβ as the targets of GCN5. Notably, the GCN5‐dependent H3K9/14 acetylation of FAD3 determined the expression levels of FAD3 in Arabidopsis thaliana seeds, and the ratio of ALA/LA in the gcn5 mutant was rescued to the wild‐type levels through the overexpression of FAD3. The results of this study indicated that GCN5 modulated FA biosynthesis by affecting the acetylation levels of FAD3. We provide evidence that histone acetylation is involved in FA biosynthesis in Arabidopsis seeds and might contribute to the optimization of the nutritional structure of edible oils through epigenetic engineering.