Changes in acyl-coenzyme A pools in sunflower seeds with modified fatty acid composition.

Triacylglycerols (TAGs) are the main reserve product accumulated by oilseeds and they are synthesized by the successive esterification of acyl-CoA derivatives to glycerol molecules through a series of reactions occurring in the endoplasmic reticulum. Acyl-CoA derivatives produced in developing seeds are derived from the de novo plastidial synthesis of fatty acids. This pool of metabolites is also implicated in the elongation of acyl chains due to the action of extraplastidial fatty acid elongases and the incorporation of polyunsaturated fatty acids into TAGs by reticular transacylase enzymes. Analyzing the composition of this pool of metabolites could help us better understand how plant lipid metabolism is regulated. In the present study, we analyzed the size and composition of the acyl-CoA pools in tissues from three sunflower mutants that accumulate oils with modified fatty acid composition. Acyl-CoAs were transformed into their corresponding acyl-etheno-CoA derivatives and analyzed by high performance liquid chromatography with fluorescence detection. We studied developing seeds, germinating cotyledons and leaf tissue to determine how mutations responsible for these traits alter the acyl-CoA pool and hence, the glycerolipid composition of the seeds. Likewise, we analyzed the metabolism of modified TAGs by cotyledons during germination. The metabolic responses of the plant and the effects of the modifications in lipid metabolism that occurred in these mutants are also discussed.