The role of phosphatidylcholine in fatty acid exchange and desaturation in Brassica napus L. leaves.
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ABSTRACT:
SUBMITTER: Williams JP
PROVIDER: S-EPMC1221129 | biostudies-other | 2000 Jul
REPOSITORIES: biostudies-other
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Project description:The expression of the FATTY ACID ELONGATION1 genes was characterised to provide insight into the regulation of very long chain fatty acid (VLCFA) biosynthesis in Brassica napus embryos. Each of the two rapeseed homoeologous genes (Bn-FAE1.1 and Bn-FAE1.2) encoding isozymes of 3-keto-acylCoA synthase, a subunit of the cytoplasmic acyl-CoA elongase complex that controls the production of elongated fatty acids, are expressed predominantly in developing seeds. The proximal regions of the Bn-FAE1.1 and Bn-FAE1.2 promoters possess strong sequence identity suggesting that transcriptional control of expression is mediated by this region which contains putative cis-elements characteristic of those found in the promoters of genes expressed in embryo and endosperm. Histochemical staining of rapeseed lines expressing Bn-FAE1.1 promoter:reporter gene fusions revealed a strong expression in the embryo cotyledon and axis throughout the maturation phase. Quantitative analyses revealed the region, -331 to -149, exerts a major control on cotyledon specific expression and the level of expression. A second region, -640 to -475, acts positively to enhance expression levels and extends expression of Bn-FAE1.1 into the axis and hypocotyl but also acts negatively to repress expression in the root meristem. The expression of the Bn-FAE1.1 gene was not restricted to the seed but was also detected in the vascular tissues of germinating seedlings and mature plants in the fascicular cambium tissue present in roots, stem and leaf petiole. We propose that Bn-FAE1.1 expression in vascular tissue may contribute VLCFA for barrier lipid synthesis and reflects the ancestral function of FAE1 encoded 3-keto-acylCoA synthase.
| S-EPMC4408364 | biostudies-literature
Project description:BackgroundThe fatty acid composition of B. napus' seeds determines the oil's nutritional and industrial values, and affects seed germination. Many studies have reported correlations among C16:0, C18:0, C18:1, C18:2 and C18:3 based on phenotypic data; however, the genetic basis of the fatty acid composition in B. napus is still not well understood.ResultsIn this study, unconditional and conditional quantitative trail locus (QTL) mapping analyses were conducted using a recombinant inbred line in six environments. In total, 21 consensus QTLs each for C16:0, C18:0 and C18:2, 16 for C18:1 and 22 for C18:3 were detected by unconditional mapping. The QTLs with overlapping confidence intervals were integrated into 71 pleiotropically unique QTLs by meta-analysis. Two major QTLs, uuqA5-6 and uuqA5-7, simultaneously affected the fatty acids, except C18:0, in most of environments, with the homologous genes fatty acid desaturase 2 (FAD2) and glycerol-3-phosphate sn-2-acyltransferase 5 (GPAT5) occurring in the confidence interval of uuqA5-6, while phosphatidic acid phosphohydrolase 1 (PAH1) was assigned to uuqA5-7. Moreover, 49, 30, 48, 60 and 45 consensus QTLs were detected for C16:0, C18:0, C18:1, C18:2 and C18:3, respectively, by the conditional mapping analysis. In total, 128 unique QTLs were subsequently integrated from the 232 conditional consensus QTLs. A comparative analysis revealed that 63 unique QTLs could be identified by both mapping methodologies, and 65 additional unique QTLs were only identified in conditional mapping.ConclusionsThus, conditional QTL mapping for fatty acids may uncover numerous additional QTLs that were inhibited by the effects of other traits. These findings provide useful information for better understanding the genetic relationships among fatty acids at the QTL level.
| S-EPMC5865336 | biostudies-literature
Project description:It is evident from previous reports that 5-aminolevulinic acid (ALA), like other known plant growth regulators, is effective in countering the injurious effects of heavy metal-stress in oilseed rape (Brassica napus L.). The present study was carried out to explore the capability of ALA to improve cadmium (Cd2+) tolerance in B. napus through physiological, molecular, and proteomic analytical approaches. Results showed that application of ALA helped the plants to adjust Cd2+-induced metabolic and photosynthetic fluorescence changes in the leaves of B. napus under Cd2+ stress. The data revealed that ALA treatment enhanced the gene expressions of antioxidant enzyme activities substantially and could increase the expression to a certain degree under Cd2+ stress conditions. In the present study, 34 protein spots were identified that differentially regulated due to Cd2+ and/or ALA treatments. Among them, 18 proteins were significantly regulated by ALA, including the proteins associated with stress related, carbohydrate metabolism, catalysis, dehydration of damaged protein, CO2 assimilation/photosynthesis and protein synthesis/regulation. From these 18 ALA-regulated proteins, 12 proteins were significantly down-regulated and 6 proteins were up-regulated. Interestingly, it was observed that ALA-induced the up-regulation of dihydrolipoyl dehydrogenase, light harvesting complex photo-system II subunit 6 and 30S ribosomal proteins in the presence of Cd2+ stress. In addition, it was also observed that ALA-induced the down-regulation in thioredoxin-like protein, 2, 3-bisphosphoglycerate, proteasome and thiamine thiazole synthase proteins under Cd2+ stress. Taken together, the present study sheds light on molecular mechanisms involved in ALA-induced Cd2+ tolerance in B. napus leaves and suggests a more active involvement of ALA in plant physiological processes than previously proposed.
| S-EPMC4409391 | biostudies-literature
Project description:Compared to ordinary rapeseed, high-oleic acid rapeseed has higher levels of monounsaturated fatty acids and lower levels of saturated fatty acid and polyunsaturated fatty acids, and thus is of high nutritional and health value. In addition, high-oleic acid rapeseed oil imparts cardiovascular protective effects. Based on these properties, high-oleic acid oil crops have been extensively investigated and cultivated. In this study, we employed a microarray analysis with high oleic acid line and low oleic acid line from the developing seeds (27 days after flowering) of Brassica napus.
2018-09-20 | GSE120223 | GEO
Project description:Fatty acids and their composition in seeds determine oil value for nutritional or industrial purposes and also affect seed germination as well as seedling establishment. To better understand the genetic basis of seed fatty acid biosynthesis in oilseed rape (Brassica napus L.) we applied a genome-wide association study, using 91,205 single nucleotide polymorphisms (SNPs) characterized across a mapping population with high-resolution skim genotyping by sequencing (SkimGBS). We identified a cluster of loci on chromosome A05 associated with oleic and linoleic seed fatty acids. The delineated genomic region contained orthologs of the Arabidopsis thaliana genes known to play a role in regulation of seed fatty acid biosynthesis such as Fatty acyl-ACP thioesterase B (FATB) and Fatty Acid Desaturase (FAD5). This approach allowed us to identify potential functional genes regulating fatty acid composition in this important oil producing crop and demonstrates that this approach can be used as a powerful tool for dissecting complex traits for B. napus improvement programs.
| S-EPMC5247464 | biostudies-literature
Project description:BACKGROUND: Synthesis of polyunsaturated fatty acids (PUFAs) in the endoplasmic reticulum of plants typically involves the fatty acid desaturases FAD2 and FAD3, which use cytochrome b(5) (Cb5) as an electron donor. Higher plants are reported to have multiple isoforms of Cb5, in contrast to a single Cb5 in mammals and yeast. Despite the wealth of information available on the roles of FAD2 and FAD3 in PUFA synthesis, information regarding the contributions of various Cb5 isoforms in desaturase-mediated reactions is limited. RESULTS: The present functional characterization of Cb5 polypeptides revealed that all Arabidopsis Cb5 isoforms are not similarly efficient in ?-6 desaturation, as evidenced by significant variation in their product outcomes in yeast-based functional assays. On the other hand, characterization of Cb5 polypeptides of soybean (Glycine max) suggested that similar ?-6 desaturation efficiencies were shared by various isoforms. With regard to ?-3 desaturation, certain Cb5 genes of both Arabidopsis and soybean were shown to facilitate the accumulation of more desaturation products than others when co-expressed with their native FAD3. Additionally, similar trends of differential desaturation product accumulation were also observed with most Cb5 genes of both soybean and Arabidopsis even if co-expressed with non-native FAD3. CONCLUSIONS: The present study reports the first description of the differential nature of the Cb5 genes of higher plants in fatty acid desaturation and further suggests that ?-3/?-6 desaturation product outcome is determined by the nature of both the Cb5 isoform and the fatty acid desaturases.
| S-EPMC3285619 | biostudies-literature
Project description:Fatty acid composition of individual species of cyanobacteria is conserved and it may be used as a phylogenetic marker. The previously proposed classification system was based solely on biochemical data. Today, new genomic data are available, which support a need to update a previously postulated FA-based classification of cyanobacteria. These changes are necessary in order to adjust and synchronize biochemical, physiological and genomic data, which may help to establish an adequate comprehensive taxonomic system for cyanobacteria in the future. Here, we propose an update to the classification system of cyanobacteria based on their fatty acid composition.
| S-EPMC4390868 | biostudies-literature
Project description:The amino acid sequence of the ferredoxin of Brassica napus was determined by using a Beckman 890C sequencer in combination with the characterization of peptides obtained by tryptic and chymotryptic digestion of the protein; some peptides were subdigested with thermolysin. The molecule consists of a single polypeptide chain of 96 amino acid residues and has an unblocked N-terminus. The primary structure shows considerable similarity with other plant-type ferredoxins.
| S-EPMC1161290 | biostudies-other
Project description:We have studied the influence of experimental hyperthyroidism in the rat on the synthesis of unsaturated fatty acids and on liver microsomal lipid fatty-acid composition. Tri-iodothyronine treatment (25 micrograms/100 g body weight) daily for 3 weeks caused no significant changes in delta 9 (stearate) desaturation but a 24% decrease in delta 6 (linoleate) desaturation. Much larger doses of tri-iodothyronine increased delta 9 desaturation. Liver microsomal fatty-acid composition in hyperthyroidism is altered with significantly increased proportions of stearate and arachidonate and decreased proportions of palmitate, palmitoleate, linoleate (C18:2) and eicosa-8,11,14-trienoate (C20:3). These changes, other than the decreases proportion of C20:3 fatty acid, which may be due to the diminished delta 6 desaturase activity, cannot be attributed to changes in fatty-acid desaturation. Most of these changes were also found to be due not simply to the decreased weight gain or the increased food intake of the hyperthyroid animals. Only the decreased C18:2 fatty-acid proportions could be mimicked by restricting food intake of control animals and none of the changes were prevented by restricting food intake of hyperthyroid animals. Thus most of the changes in microsomal lipid fatty-acid composition are likely to be due to a thyroid hormone effect on peripheral lipid mobilization or lipid degradation.
| S-EPMC1162676 | biostudies-other
Project description:We have studied the influence of experimental hypothyroidism in the rat on the synthesis of unsaturated fatty acids and on liver microsomal lipid fatty acid composition. Hypothyroid rats demonstrated an 80% decrease in delta 9 (stearate) desaturation and a 43% decrease in delta 6 (linoleate) desaturation. Liver microsomal fatty acid composition was altered in the hypothyroid animals with a significantly decreased proportion of arachidonate and increased proportions of linoleate, eicosa-8,11,14-trienoate, eicosapentaenoate and docosahexaenoate. The bulk of these changes occurred in both of the two major phospholipid components, phosphatidylcholine and phosphatidylethanolamine. All of the changes were corrected by treatment of the hypothyroid rat with 25 micrograms of tri-iodothyronine/100 g body wt. twice daily. The diminished delta 9 desaturation did not lead to any changes in fatty acid composition. The increased linoleate and decreased arachidonate levels may be due to the diminished delta 6 desaturase activity, the rate-controlling step in the conversion of linoleate into arachidonate. The increases in the proportions of the other polyunsaturated fatty acid components cannot be explained by changes in the synthesis of unsaturated fatty acids, but are probably due to diminished utilization of these fatty acids.
| S-EPMC1153819 | biostudies-other