Current address: Section of Plant Biology, University of California–Davis, One Shields Avenue, Davis, CA 95616-5270, USA.
Acyl CoA profiles of transgenic plants that accumulate medium-chain fatty acids indicate inefficient storage lipid synthesis in developing oilseeds
Article first published online: 19 NOV 2002
The Plant Journal
Volume 32, Issue 4, pages 519–527, November 2002
How to Cite
Larson, T. R., Edgell, T., Byrne, J., Dehesh, K. and Graham, I. A. (2002), Acyl CoA profiles of transgenic plants that accumulate medium-chain fatty acids indicate inefficient storage lipid synthesis in developing oilseeds. The Plant Journal, 32: 519–527. doi: 10.1046/j.1365-313X.2002.01440.x
- Issue published online: 19 NOV 2002
- Article first published online: 19 NOV 2002
- Received 20 June 2002; revised 24 July 2002; accepted 25 July 2002.
- acyl CoA;
- Brassica napus;
- lipid synthesis;
- medium-chain fatty acids
Several Brassica napus lines transformed with genes responsible for the synthesis of medium- or long-chain fatty acids were examined to determine limiting factor(s) for the subsequent accumulation of these fatty acids in seed lipids. Examination of a decanoic acid (10:0) accumulating line revealed a disproportionately high concentration of 10:0 CoA during seed development compared to long-chain acyl CoAs isolated from the same tissues, suggesting that poor incorporation of 10:0 CoA into seed lipids limits 10:0 fatty acid accumulation. This relationship was also seen for dodecanoyl (12:0) CoA and fatty acid in a high 12:0 line, but not for octadecanoic (18:0) CoA and fatty acid in a high 18:0 line. Comparison of 10:0 CoA and fatty acid proportions from seeds at different developmental stages for transgenic B. napus and Cuphea hookeriana, the source plant for the medium-chain thioesterase and 3-ketoacyl-ACP synthase transgenes, revealed that C. hookeriana incorporates 10:0 CoA into seed lipids more efficiently than transgenic B. napus. Furthermore, β-oxidation and glyoxylate cycle activities were not increased above wild type levels during seed development in the 8:0/10:0 line, suggesting that lipid catabolism was not being induced in response to the elevated 10:0 CoA concentrations. Taken together, these data suggest that transgenic plants that are engineered to synthesize medium-chain fatty acids may lack the necessary mechanisms, such as specific acyltransferases, to incorporate these fatty acids efficiently into seed lipids.