Abstract
During their rapid maturation period, seeds of Cuphea wrightii A. Gray mainly accumulate medium-chain fatty acids (C8 to C14) in their storage lipids. The rate of lipid deposition (40–50 mg·d−1·(g fresh weight)−1) is fourfold higher than in seeds of Cuphea racemosa (L. f.) Spreng, which accumulate long-chain fatty acids (C16 to C18). Measurements of the key enzymes of fatty-acid synthesis in cell-free extracts of seeds of different maturities from Cuphea wrightii show that malonyl-CoA synthesis may be a triggering factor for the observed high capacity for fatty-acid synthesis. Experiments on the incorporation of [1-14C]acetate into fatty acids by purified plastid preparations from embryos of Cuphea wrightii have demonstrated that the biosynthesis of medium-chain fatty acids (C8 to C14) is localized in the plastid. Thus, in the presence of cofactors for lipid synthesis (ATP, NADPH, NADH, acyl carrier protein, and sn-glycerol-3-phosphate), purified plastid fractions predominantly synthesized free fatty acids, 30% of which were of medium chain length. Transesterification of the freshly synthesized fatty acids to coenzyme A and recombination with the microsomal fraction of the embryo homogenate induced triacylglycerol synthesis. It also stimulated fatty-acid synthesis by a factor 2–3 and increased the relative amount of medium-chain fatty acids bound to triacylglycerols, which corresponded to about 60–80% in this lipid fraction.
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Abbreviations
- ACP:
-
acyl carrier protein
- FW:
-
fresh weight
References
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This work was supported by the Bundesminister für Forschung und Technologie. The authors thank S. Borchert for her suggestions for plastid preparation.
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Deerberg, S., von Twickel, J., Förster, HH. et al. Synthesis of medium-chain fatty acids and their incorporation into triacylglycerols by cell-free fractions from Cuphea embryos. Planta 180, 440–444 (1990). https://doi.org/10.1007/BF00198798
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DOI: https://doi.org/10.1007/BF00198798