Document Detail


Gene expression of stearoyl-ACP desaturase and delta12 fatty acid desaturase 2 is modulated during seed development of flax (Linum usitatissimum).
MedLine Citation:
PMID:  17069354     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Flax's recent popularity in human and animal foods is mostly due to its desirable FA composition. Flax is an excellent source of omega-3 FA, which have been shown to have many health benefits. To date, little is known about the genetic and environmental factors that control the FA composition of flax seeds. To elucidate some of the important genetic components, reverse transcriptase (RT)-PCR and real-time PCR were used to determine the expression profiles of two key FA biosynthetic genes during seed development. Plants of flax cultivar AC McDuff were grown under field conditions, and RNA was extracted from ovaries and developing bolls collected from 2 d after anthesis (DAA) to maturity. Desaturation enzymes stearoyl-ACP desaturase (SAD) and delta12 FA desaturase 2 (FAD2) were both expressed in ovaries, and their expression was differentially modulated throughout seed development. SAD was most highly expressed in ovaries. Its expression quickly decreased until 4 DAA; this was followed by a slight peak at 8 DAA, only to return to relatively low levels of expression in maturing bolls, ranging from 2.1% to 4.5% relative to the level observed in ovaries. FAD2 expression displayed a different temporal pattern. While expression of FAD2 did decrease in the early stages of seed development, expression increased starting at 8 DAA, peaking at 16 DAA, when it was 158% relative to the level observed in ovaries. FAD2, which desaturates oleic acid (18:1cisdelta9) into linoleic acid (18:2cisdelta9,12), is therefore controlled at the transcription level. To relate enzyme expression with FA profile, GC was performed on the same subsamples used for RT-PCR and real-time PCR, and proportions of palmitic, stearic, oleic, linoleic, and linolenic acids were determined for the same developmental stages. Although FAD2 expression increased from 8 to 16 DAA, relative changes in linoleic acid (18:2cis delta9,12) were not observed. However, linolenic acid (ALA; alpha-18:3; 18:3cisdelta9,12,15) levels increased steadily, meaning that linoleic acid (18:2cisdelta9,12) is a transient substrate converted by FAD3 as quickly as it is produced by FAD2. Phenotypes are the result of genotypes, environment, and the interaction of the two. To evaluate the environmental impact on the production of FA in flax, FA profiles were assessed in a total of four environments (two locations, two years). Warm and dry environmental conditions resulted in lower levels of PUFA 18:2cisdelta9,12 and 18:3cisdelta9,12,15, and higher levels of 18:1 cisdelta9. FAD2 expression and/or activity may therefore be affected by the environment.
Authors:
Bourlaye Fofana; Sylvie Cloutier; Scott Duguid; Jacqueline Ching; Chris Rampitsch
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Lipids     Volume:  41     ISSN:  0024-4201     ISO Abbreviation:  Lipids     Publication Date:  2006 Jul 
Date Detail:
Created Date:  2006-10-30     Completed Date:  2006-11-14     Revised Date:  2012-05-24    
Medline Journal Info:
Nlm Unique ID:  0060450     Medline TA:  Lipids     Country:  United States    
Other Details:
Languages:  eng     Pagination:  705-12     Citation Subset:  IM    
Affiliation:
Cereal Research Centre, Agriculture and Agri-Food Canada, 195 Dafoe Rd., Winnipeg, MB, Canada R3T 2M9.
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MeSH Terms
Descriptor/Qualifier:
Base Sequence
Chromatography, Gas
Fatty Acid Desaturases / genetics*,  metabolism
Fatty Acids / analysis,  biosynthesis*
Flax / growth & development,  metabolism*
Gene Expression Regulation, Plant*
Mixed Function Oxygenases / genetics*,  metabolism
Molecular Sequence Data
Seeds / growth & development,  metabolism*
Chemical
Reg. No./Substance:
0/Fatty Acids; EC 1.-/Mixed Function Oxygenases; EC 1.14.19.-/Fatty Acid Desaturases; EC 1.14.19.2/acyl-(acyl-carrier-protein)desaturase; EC 1.14.99.-/delta-12 fatty acid desaturase

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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