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evolution
three histidine clusters characteristic of fatty acid desaturases, a putative chloroplast transit peptide in the N-terminal, and three putative transmembrane domains are identified in the enzyme sequence
metabolism
glycine betaine protects tomato plants at low temperature by inducing fatty acid desaturase7 and lipoxygenase gene expression, providing protection against cold stress in tomato plants which might be related to the desaturation process of lipids leading to increased membrane stability and/or induction of other genes related to stress defense mechanisms via octadecanoid pathway or lipid peroxidation products
malfunction
in a genetic background that is wild type at the FAD7 locus, the fad8 mutation has no detedable effed on overall leaf fatty acid composition irrespective of the temperature at which plants are grown. However, fatty acid analyses of individual leaf lipids reveales small decreases in the levels of 18:3 in two chloroplast lipids. In fad8 plants grown at 22°C, phosphatidylglycerol contains 22.5% 18:3 compared with 33.5% in wild type Arabidopsis
malfunction
mutations at the fad7 locus of Arabidopsis thaliana cause decreased desaturation of dienoic fatty acids in chloroplast lipids in plants grown at elevated temperatures
malfunction
mutations at the fad7 locus of Arabidopsis thaliana cause decreased desaturation of dienoic fatty acids in chloroplast lipids in plants grown at elevated temperatures
malfunction
a fad8 mutant shows no significant changes in its fatty acid profile at a control (22°C) temperature, while at lower temperature (15°C) the mutant shows a phenotype, leaf lipid analysis, overview
malfunction
comparison of trienoic fatty acid levels in wild-type and fad7 mutant leaves, an increase occurs in the wild-type at 15-26°C during maturation mainly due to galactolipids enriched in plastid membranes, while in mutant leaves at 26°C the levels decrease with leaf maturation, overview
malfunction
in contrast to avirulent petiole exudates from wild-type plants, avirulent petiole exudates from fad7, sfd1 and sfd2 mutants are unable to activate systemic acquired resistance when applied to wild-type plants. The SAR-inducing activity is reconstituted by mixing avirulent petiole exudates collected from fad7 and sfd1 with avirulent petiole exudate from the SAR-deficient dir1 mutant
malfunction
mutant fad7i maintains 74% of 18:3 production with respect to Col-0 while only 23% of 16:3 synthesis is maintained in this mutant. The fad7/fad8 double mutant also shows a considerable reduction in trienoic fatty acids, particularly in 16:3, which is undetectable. After disruption of the AtFAD7 gene, enzyme FAD8 enzymatic activity is able to maintain, at least partially (43.7%), the amount of 18:3 and to a much lesser extent that of 16:3 (23.2%) at 22°C
malfunction
the omega-3 fatty acids hexadecatrienoic acid (C16:3n3), hexadecatetraenoic acid (C16:4),and alpha-linolenic acid (C18:3n3) are not detected in the CC-620 strain, phenotype and fatty acid composition of the omega-3 fatty acid deficiency in strain CC-620 due to the missense mutation detected in gene CrFAD7, complementation by the wild-type enzyme, overview
malfunction
leaf lipid analysis of the Arabidopsis omega-3 desaturase fad7 mutant line at growth temperature of 22°C, overview. Disruption of the AtFAD7 gene in fad7i mutant results in a reduction of TAs with an 18:3 content of 29.6% and an even more reduced content of 16:3 down to 2%. Mutant fad7i maintains 74% of 18:3 production with respect to wild-type Col-0 while only 23% of 16:3 synthesis is maintained in the mutant
malfunction
osfad8 knockout mutant plants exhibit significant alterations in fatty acid unsaturation for all four investigated plastidic lipid classes. During a 5-day acclimation period at 4°C, further changes in fatty acid unsaturation in both wild-type and mutant plants vary according to the type of lipid. The fluidity of the thylakoid membrane are altered significantly by both FAD8 mutation and cold acclimation, suggesting that factors other than FAD8 are involved in C18 fatty acid unsaturation and fluctuations in membrane fluidity. Similarly, significant changes are noted for both the mutant and wild-type samples in terms of their fatty acid compositions as well as activities related to photosystem (PS) I, PSII, and photoprotection. This includes the development of non-photochemical quenching and increased zeaxanthin accumulation. Despite the relatively small changes in fatty acid composition during cold acclimation, cold-inducible FAD8 knock-out mutants display strong differences in photoprotective activities and a further drop in membrane fluidity. The mutants are more sensitive than wild-type to short-term low-temperature stress that results in increased production of reactive oxygen species after 5 days of chilling. The levels of 18:3 are reduced by 20% in the fad8 knockout mutant compared to wild-type, while the levels of 18:2 are increased 2fold. Phenotype, overview
malfunction
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leaf lipid analysis of the Arabidopsis omega-3 desaturase fad7 mutant line at growth temperature of 22°C, overview. Disruption of the AtFAD7 gene in fad7i mutant results in a reduction of TAs with an 18:3 content of 29.6% and an even more reduced content of 16:3 down to 2%. Mutant fad7i maintains 74% of 18:3 production with respect to wild-type Col-0 while only 23% of 16:3 synthesis is maintained in the mutant
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malfunction
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mutant fad7i maintains 74% of 18:3 production with respect to Col-0 while only 23% of 16:3 synthesis is maintained in this mutant. The fad7/fad8 double mutant also shows a considerable reduction in trienoic fatty acids, particularly in 16:3, which is undetectable. After disruption of the AtFAD7 gene, enzyme FAD8 enzymatic activity is able to maintain, at least partially (43.7%), the amount of 18:3 and to a much lesser extent that of 16:3 (23.2%) at 22°C
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malfunction
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comparison of trienoic fatty acid levels in wild-type and fad7 mutant leaves, an increase occurs in the wild-type at 15-26°C during maturation mainly due to galactolipids enriched in plastid membranes, while in mutant leaves at 26°C the levels decrease with leaf maturation, overview
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malfunction
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a fad8 mutant shows no significant changes in its fatty acid profile at a control (22°C) temperature, while at lower temperature (15°C) the mutant shows a phenotype, leaf lipid analysis, overview
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physiological function
FAD7-synthesized lipids provide fatty acids for synthesis of jasmonic acid. Petiole exudates collected from Arabidopsis leaves inoculated with an avirulent Pseudomonas syringae strain promote systemic acquired resistance, SAR, when applied to Arabidopsis thaliana. Arabidopsis fatty acid desaturase7, suppressor of fatty acid desaturase deficiency 1 (SFD1), and SFD2 genes are required for accumulation of the SAR-inducing activity. Jasmonic acid and methyljasmonic acid with avirulent petiole exudate from fad7 and sfd1 does not reconstitute the SAR-inducing activity. A plastid glycerolipid-dependent factor is required in avirulent petiole exudate along with the DIR1-encoded lipid transfer protein for long-distance signaling in systemic acquired resistance
physiological function
fatty acid desaturases catalyze the introduction of double bonds into the aliphatic tails of fatty acids which affects plant responses against a variety of stresses via the enhancement of membrane fluidity
physiological function
plastidial omega-3 desaturases FAD7 and FAD8 are major contributors to trienoic fatty acid biosynthesis in the leaves of Arabidopsis thaliana plants. Enzyme FAD8 partially compensates the disruption of the AtFAD7 gene at 22°C
physiological function
plastidial omega-3 desaturases FAD7 and FAD8 are major contributors to trienoic fatty acid biosynthesis in the leaves of Arabidopsis thaliana plants. Enzyme FAD8 partially compensates the disruption of the AtFAD7 gene at 22°C, indicating that enzyme FAD8 is active at this growth temperature, contrasting to previous observations that circumscribe the FAD8 activity at low temperatures
physiological function
role of omega-3 fatty acid desaturases in the positive regulation of the level of trienoic fatty acids during leaf cell maturation
physiological function
the plastidial omega-3 fatty acid desaturase FAD7 catalyzes the desaturation of dienoic fatty acids in membrane lipids
physiological function
the role of fad8 is to provide increased omega3 desaturase activity in plants that are exposed to low growth temperature
physiological function
Thr residue located in the fourth transmembrane domain of fatty acid desaturase 7 (FAD7) that is essential for the biosynthesis of omega-3 fatty acids in Chlamydomonas reinhardtii, Thr286 is essential for the maintaining the catalytic structure of the enzyme
physiological function
plastidial omega-3 desaturase FAD7 is a major contributor to trienoic fatty acid biosynthesis in the leaves of Arabidopsis thaliana plants. Differences in the mechanism controlling AtFAD7 and AtFAD8 gene expression at different temperatures, the function of both plastidial omega-3 desaturases is coordinated in a non-redundant manner
physiological function
the plastidial omega-3-fatty acid desaturases CsFAD7 and CsFAD8 are both responsive to abiotic stress signals, but they may play very different roles during stress tolerance in tea plants
physiological function
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plastidial omega-3 desaturase FAD7 is a major contributor to trienoic fatty acid biosynthesis in the leaves of Arabidopsis thaliana plants. Differences in the mechanism controlling AtFAD7 and AtFAD8 gene expression at different temperatures, the function of both plastidial omega-3 desaturases is coordinated in a non-redundant manner
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physiological function
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plastidial omega-3 desaturases FAD7 and FAD8 are major contributors to trienoic fatty acid biosynthesis in the leaves of Arabidopsis thaliana plants. Enzyme FAD8 partially compensates the disruption of the AtFAD7 gene at 22°C
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physiological function
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the plastidial omega-3 fatty acid desaturase FAD7 catalyzes the desaturation of dienoic fatty acids in membrane lipids
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physiological function
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role of omega-3 fatty acid desaturases in the positive regulation of the level of trienoic fatty acids during leaf cell maturation
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physiological function
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plastidial omega-3 desaturases FAD7 and FAD8 are major contributors to trienoic fatty acid biosynthesis in the leaves of Arabidopsis thaliana plants. Enzyme FAD8 partially compensates the disruption of the AtFAD7 gene at 22°C, indicating that enzyme FAD8 is active at this growth temperature, contrasting to previous observations that circumscribe the FAD8 activity at low temperatures
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physiological function
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the role of fad8 is to provide increased omega3 desaturase activity in plants that are exposed to low growth temperature
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additional information
ectopic overexpression of FAD8 induces an increased ratio mainly in the plastidic lipids. Overexpression of FAD8 leads to increased tolerance to osmotic stress (imposed by two different agents, PEG 8000 and sorbitol) and decreased tolerance to heat stress (35°C), at both cellular and whole-plant levels. FAD8-overexpressing plants can regain growth after withholding water for a duration that severely impaires the ability of wild-type plants to recover from the stress. Fatty acid composition of leaf polar lipids of wild-type and transgenic plants, overview
additional information
elevated temperatures lead to decreases in leaf trienoic fatty acid level due to temperature sensitivity of enzyme FAD8 activity, the C-terminal region of FAD8 desaturase is essential for destabilization at high temperature (22°C). The C-terminal coding region of FAD8 is sufficient to suppress the accumulation of plastidial omega-3 desaturase protein at high temperature, overview
additional information
elevated temperatures lead to decreases in leaf trienoic fatty acid level due to temperature sensitivity of enzyme FAD8 activity, the C-terminal region of FAD8 desaturase is essential for destabilization at high temperature (22°C). The C-terminal coding region of FAD8 is sufficient to suppress the accumulation of plastidial omega-3 desaturase protein at high temperature, overview
additional information
FAD8-YFP over-expressing lines show a specific increase in 18:3 fatty acids at 22°C. Residue 103 is part of the first His box essential for desaturase function
additional information
FAD8-YFP over-expressing lines show a specific increase in 18:3 fatty acids at 22°C. Residue 103 is part of the first His box essential for desaturase function
additional information
increased levels of trienoic fatty acids in genetically engineered plants enhance cold tolerance
additional information
wounding changes the spatial expression pattern of the FAD7 gene
additional information
fatty acids contents (mol%) in leaves from wild-type rice and osfad8 mutant lines at 4°C and 28°C, overview. Membrane fluidity of rice plants is altered with altered fatty acid compositions
additional information
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wounding changes the spatial expression pattern of the FAD7 gene
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additional information
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increased levels of trienoic fatty acids in genetically engineered plants enhance cold tolerance
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additional information
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elevated temperatures lead to decreases in leaf trienoic fatty acid level due to temperature sensitivity of enzyme FAD8 activity, the C-terminal region of FAD8 desaturase is essential for destabilization at high temperature (22°C). The C-terminal coding region of FAD8 is sufficient to suppress the accumulation of plastidial omega-3 desaturase protein at high temperature, overview
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additional information
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FAD8-YFP over-expressing lines show a specific increase in 18:3 fatty acids at 22°C. Residue 103 is part of the first His box essential for desaturase function
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additional information
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ectopic overexpression of FAD8 induces an increased ratio mainly in the plastidic lipids. Overexpression of FAD8 leads to increased tolerance to osmotic stress (imposed by two different agents, PEG 8000 and sorbitol) and decreased tolerance to heat stress (35°C), at both cellular and whole-plant levels. FAD8-overexpressing plants can regain growth after withholding water for a duration that severely impaires the ability of wild-type plants to recover from the stress. Fatty acid composition of leaf polar lipids of wild-type and transgenic plants, overview
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