Fatty acid biosynthesis in the leaves of barley, wheat and pea.
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ABSTRACT:
SUBMITTER: Wharfe J
PROVIDER: S-EPMC1185896 | biostudies-other | 1978 Jul
REPOSITORIES: biostudies-other
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Project description:1. Fatty acid synthesis was studied in microsomal preparations from germinating pea (Pisum sativum). 2. The preparations synthesized a mixture of saturated fatty acids up to a chain length of C(24) from [(14)C]malonyl-CoA. 3. Whereas hexadecanoic acid was made de novo, octadecanoic acid and icosanoic acid were synthesized by elongation. 4. The products formed during [(14)C]malonyl-CoA incubation were analysed, and unesterified fatty acids and polar lipids were found to be major products. [(14)C]Palmitic acid represented a high percentage of the acyl-carrier protein esters, whereas (14)C-labelled very-long-chain fatty acids were mainly present as unesterified fatty acids. CoA esters were minor products. 5. The addition of exogenous lipids to the incubation system usually resulted in stimulation of [(14)C]malonyl-CoA incorporation into fatty acids. The greatest stimulation was obtained with dipalmitoyl phosphatidylcholine. Both exogenous palmitic acid and dipalmitoyl phosphatidylcholine increased the amount of [(14)C]-stearic acid synthesized, relative to [(14)C]palmitic acid. Addition of stearic acid increased the amount of [(14)C]icosanoic acid formed. 6. [(14)C]Stearic acid was elongated more effectively to icosanoic acid than [(14)C]stearoyl-CoA, and its conversion was not decreased by addition of unlabelled stearoyl-CoA. 7. Incorporation of [(14)C]malonyl-CoA into fatty acids was markedly decreased by iodoacetamide and 5,5'-dithiobis-(2-nitrobenzoic acid). Palmitate elongation was sensitive to arsenite addition, and stearate elongation to the presence of Triton X-100 or fluoride. The action of fluoride was not, apparently, due to chelation. 8. The microsomal preparations differed from soluble fractions from germinating pea in (a) synthesizing very-long-chain fatty acids, (b) not utilizing exogenous palmitate-acyl-carrier protein as a substrate for palmitate elongation and (c) having fatty acid synthesis stimulated by the addition of certain complex lipids.
| S-EPMC1183759 | biostudies-other
Project description:Concentrations of fluazifop-butyl sprayed on intact plants caused large decreases in the incorporation of radioactivity from [1-14C]acetate into lipids of barley (Hordeum vulgare) leaves and stems, but did not affect leaves or stems of pea (Pisum sativum). Labelling of all acyl lipids, but not pigments, was reduced. The effects of the active acid form, fluazifop, were also determined in leaf pieces and chloroplasts. Concentrations of (R,S)-fluazifop up to 100 microM had no affect upon quality or quantity of fatty acids produced from [1-14C]acetate in pea. In barley, however, 100 microM-(R,S)-fluazifop caused 89% (leaf) or 100% (chloroplasts) inhibition in labelling of fatty acids from [1-14C]acetate. Lower concentrations of fluazifop (less than 25 microM) caused incomplete inhibition and significant decreases in the proportion of C18 fatty acids synthesized, particularly by isolated chloroplasts. Synthesis of fatty acids from [2-14C]malonate was also inhibited (59%) in barley leaf tissue by 100 microM-(R,S)-fluazifop. The labelling pattern of products showed that elongation reactions were unaffected by the herbicide, but synthesis de novo was specifically diminished. By using resolved stereoisomers, it was found that the (R) isomer was the form which inhibited fatty acid synthesis, a finding that is in agreement with its herbicidal activity. These results suggest that inhibition of fatty acid synthesis de novo forms the basis for the selective mode of action of fluazifop.
| S-EPMC1135155 | biostudies-other
Project description:The wheat gene Lr34 (Yr18/Pm38/Sr57/Ltn1) encodes a putative ABCG-type of transporter and is a unique source of disease resistance providing durable and partial resistance against multiple fungal pathogens. Lr34 has been found to be functional as a transgene in barley. We used microarrays to decipher the changes in global gene expression goverened by Lr34 expression in barley.
2015-07-01 | GSE64228 | GEO
Project description:Fatty acids are essential components of biological membranes, important for the maintenance of cellular structures, especially in organisms with complex life cycles like protozoan parasites. Apicomplexans are obligate parasites responsible for various deadly diseases of humans and livestock. We analyzed the fatty acids produced by the closest phototrophic relatives of parasitic apicomplexans, the chromerids Chromera velia and Vitrella brassicaformis, and investigated the genes coding for enzymes involved in fatty acids biosynthesis in chromerids, in comparison to their parasitic relatives. Based on evidence from genomic and metabolomic data, we propose a model of fatty acid synthesis in chromerids: the plastid-localized FAS-II pathway is responsible for the de novo synthesis of fatty acids reaching the maximum length of 18 carbon units. Short saturated fatty acids (C14:0-C18:0) originate from the plastid are then elongated and desaturated in the cytosol and the endoplasmic reticulum. We identified giant FAS I-like multi-modular enzymes in both chromerids, which seem to be involved in polyketide synthesis and fatty acid elongation. This full-scale description of the biosynthesis of fatty acids and their derivatives provides important insights into the reductive evolutionary transition of a phototropic algal ancestor to obligate parasites.
| S-EPMC7464705 | biostudies-literature
Project description:The plant-specific WRINKLED1 (WRI1) is a member of the AP2/EREBP class of transcription factors that positively regulate oil biosynthesis in plant tissues. Limited information is available for the role of WRI1 in oil biosynthesis in castor bean (Ricinus connunis L.), an important industrial oil crop. Here, we report the identification of two alternatively spliced transcripts of RcWRI1, designated as RcWRI1-A and RcWRI1-B. The open reading frames of RcWRI1-A (1341 bp) and RcWRI1-B (1332 bp) differ by a stretch of 9 bp, such that the predicted RcWRI1-B lacks the three amino acid residues "VYL" that are present in RcWRI1-A. The RcWRI1-A transcript is present in flowers, leaves, pericarps and developing seeds, while the RcWRI1-B mRNA is only detectable in developing seeds. When the two isoforms were individually introduced into an Arabidopsiswri1-1 loss-of-function mutant, total fatty acid content was almost restored to the wild-type level, and the percentage of the wrinkled seeds was largely reduced in the transgenic lines relative to the wri1-1 mutant line. Transient expression of each RcWRI1 splice isoform in N. benthamiana leaves upregulated the expression of the WRI1 target genes, and consequently increased the oil content by 4.3-4.9 fold when compared with the controls, and RcWRI1-B appeared to be more active than RcWRI1-A. Both RcWRI1-A and RcWRI1-B can be used as a key transcriptional regulator to enhance fatty acid and oil biosynthesis in leafy biomass.
| S-EPMC5796095 | biostudies-literature
Project description:Wheat (Triticum aestivum L.) is one of the most important crops in the world. Chlorophyll plays a vital role in plant development and crop improvement and further determines the crop productivity to a certain extent. The biosynthesis of chlorophyll remains a complex metabolic process, and fundamental biochemical discoveries have resulted from studies of plant mutants with altered leaf color. In this study, we identified a chlorophyll-deficiency mutant, referred to as chli, from the wheat cultivar Shaannong33 that exhibited an obvious pale-green leaf phenotype at the seedling stage, with significantly decreased accumulation of chlorophyll and its precursors, protoporphyrin IX and Mg-protoporphyrin IX. Interestingly, a higher protoporphyrin IX to Mg-protoporphyrin IX ratio was observed in chli. Lipid biosynthesis in chli leaves and seeds was also affected, with the mutant displaying significantly reduced total lipid content relative to Shaanong33. Genetic analysis indicated that the pale-green leaf phenotype was controlled by a single pair of recessive nuclear genes. Furthermore, sequence alignment revealed a single-nucleotide mutation (G664A) in the gene TraesCS7A01G480700.1, which encodes subunit I of the Mg-chelatase in plants. This single-nucleotide mutation resulted in an amino acid substitution (D221N) in the highly conserved domain of subunit I. As a result, mutant protein Tachli-7A lost the ability to interact with the normal protein TaCHLI-7A, as assessed by yeast two-hybrid assay. Meanwhile, Tachli-7A could not recover the chlorophyll deficiency phenotype of the Arabidopsis thaliana SALK_050029 mutant. Furthermore, we found that in Shaannong33, the protoporphyrin IX to Mg-protoporphyrin IX ratio was growth state-dependent and insensitive to environmental change. Overall, the mutation in Tachli-7A impaired the function of Mg-chelatase and blocked the conversion of protoporphyrin IX to Mg- protoporphyrin IX. Based on our results, the chli mutant represents a potentially useful resource for better understanding chlorophyll and lipid biosynthetic pathways in common wheat.
| S-EPMC7046076 | biostudies-literature
Project description:1. The total RNA and the RNA present in 27000g pellet (probably composed of chloroplasts, nuclei and mitochondria) and in 27000g supernatant (probably composed of microsomes and soluble proteins) fractions (separated by centrifugation at 27000g of a leaf homogenate prepared in 0.5m-sucrose-0.02m-tris-HCl, pH7.6) of barley leaves were extracted by phenol-sodium lauryl sulphate and their elution profiles on Sephadex G-200 and on ECTEOLA-cellulose anion-exchanger were examined and their nucleotide compositions and the melting curves were determined. 2. The pellet and the supernatant fractions contained respectively about 55% and 20% of the total RNA, whereas 25% of the total RNA was lost during homogenization of the leaf tissue with sucrose-buffer. 3. The total RNA or the RNA from pellet or supernatant fractions, which by its behaviour on Sephadex G-200 columns was found to be predominantly of high molecular weight (i.e. of ribosomal origin), produced about 13 peaks on ECTEOLA-cellulose columns. The RNA species in the pellet and supernatant fractions probably resembled each other in molecular size or secondary structure or both. However, they were present in relatively different amounts in these fractions. 4. The T(m) (i.e. the temperature at which 50% of the maximal increase in extinction had occurred) of total RNA and of RNA from pellet fraction was 64.5 degrees whereas T(m) of RNA from the supernatant fraction was 73 degrees . The total RNA and the RNA from pellet fraction also resembled each other in nucleotide composition, and the RNA from the supernatant fraction in accordance with its high T(m) had a high GMP+CMP content.
| S-EPMC1207201 | biostudies-other
Project description:Bacterial symbionts associated with insects are often involved in host development and ecological adaptation. Serratia symbiotica, a common facultative endosymbiont harbored in pea aphids, improves host fitness and heat tolerance, but studies concerning the nutritional metabolism and impact on the aphid host associated with carrying Serratia are limited. In the current study, we showed that Serratia-infected aphids had a shorter nymphal developmental time and higher body weight than Serratia-free aphids when fed on detached leaves. Genes connecting to fatty acid biosynthesis and elongation were up-regulated in Serratia-infected aphids. Specifically, elevated expression of fatty acid synthase 1 (FASN1) and diacylglycerol-o-acyltransferase 2 (DGAT2) could result in accumulation of myristic acid, palmitic acid, linoleic acid, and arachidic acid in fat bodies. Impairing fatty acid synthesis in Serratia-infected pea aphids either by a pharmacological inhibitor or through silencing FASN1 and DGAT2 expression prolonged the nymphal growth period and decreased the aphid body weight. Conversely, supplementation of myristic acid (C14:0) to these aphids restored their normal development and weight gain. Our results indicated that Serratia promoted development and growth of its aphid host through enhancing fatty acid biosynthesis. Our discovery has shed more light on nutritional effects underlying the symbiosis between aphids and facultative endosymbionts.
| S-EPMC8199403 | biostudies-literature
Project description:1. Although isolated spinach chloroplasts were almost entirely (greater than 99%) dependent on light for fatty acid synthesis, leaf discs were capable of fatty acid synthesis in the dark (up to 500nmol of 3H/h per mg of chlorophyll equivalent to approx. 400nmol of carbon/h per mg of chlorophyll), which represented 12-20% of the corresponding 'light rates'. 2. Net fatty acid accumulation by greening maize leaves occurred largely or entirely during the light period. 3. There was a diurnal fluctuation in the proportions of C18 unsaturated fatty acids in the lipids of developing spinach leaves, where an increase in the concentration of oleate during the day and a subsequent decline at night was observed; a complementary change occurred in the concentration of alpha-linolenate. The rhythm is interpreted as reflecting the continuation of oleate and linoleate desaturation at high rates when oleate synthesis is markedly decreased at night. 4. Changes in the fatty acid composition of 3-sn-phosphatidylcholine accounted for at least 60% of the total decrease in oleate over the dark period. This result is consistent with suggestions that this lipid is the substrate for the leaf microsomal oleate desaturase and an intermediate in leaf glycerolipid biosynthesis.
| S-EPMC1162999 | biostudies-other
Project description:The wheat gene Lr34 (Yr18/Pm38/Sr57/Ltn1) encodes a putative ABCG-type of transporter and is a unique source of disease resistance providing durable and partial resistance against multiple fungal pathogens. Lr34 has been found to be functional as a transgene in barley. We used microarrays to decipher the changes in global gene expression governed by Lr34 expression in barley. Leaves from two independent lines of transgenic barley plants were selected at seedling (two weeks old plants) and mature (six weeks old plants) stages of development for RNA extraction and hybridization on Affymetrix microarrays. We used three biological replicates for expression profiles. Wild type plants served as controls.
2015-07-01 | E-GEOD-64228 | biostudies-arrayexpress