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Storage lipid accumulation and acyltransferase action in developing flaxseed
Brent M Sørensen1, Tara L Furukawa-Stoffer, Kris S Marshall
1Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, Canada.
Lipids
|December 31, 2005
Summary
Flaxseed oil content increases during development, with alpha-linolenic acid proportions rising. Key enzymes like DGAT and LPAAT show specificities, suggesting potential for enhancing nutritional fatty acids in flaxseed.
Area of Science:
- Plant biochemistry and crop science
- Lipid metabolism and seed development
Background:
- Flaxseed (Linum usitatissimum) is a valuable crop for its oil and nutritional content.
- Understanding lipid synthesis is crucial for improving flaxseed oil quality and quantity.
Purpose of the Study:
- To investigate lipid accumulation and fatty acid composition during flaxseed development.
- To characterize the substrate specificity of key enzymes involved in triacylglycerol (TAG) synthesis.
Main Methods:
- Analysis of lipid content and fatty acid profiles in two flax cultivars (AC Emerson and Vimy) at different developmental stages.
- Enzyme assays examining the activity and substrate specificity of microsomal diacylglycerol acyltransferase (DGAT) and lysophosphatidic acid acyltransferase (LPAAT) using various acyl-CoAs, including EPA and DHA.
Main Results:
- Oil content increased steadily until approximately 20 days after flowering (DAF).
- Alpha-linolenic acid (alpha-18:3) proportion increased, while linoleic acid (18:2) and saturated fatty acids decreased during development.
- DGAT showed higher specificity for alpha-18:3-CoA, and LPAAT preferred 18:2-CoA. Both enzymes utilized EPA-CoA and DHA-CoA to some extent.
- Flax embryos incorporated EPA and DHA into TAG.
Conclusions:
- Flaxseed development involves dynamic changes in lipid content and fatty acid composition.
- Enzyme specificities suggest potential targets for genetic modification to enhance nutritional fatty acids.
- Introducing desaturation/elongation pathways could enable conversion of alpha-18:3 to EPA for improved TAG formation in flaxseed.