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Multiple Pathways of Linolenic Acid Synthesis Operate and Interact in Leaf Tissue

  • Helen A. Norman
  • Judith B. St. John

Abstract

Different biosynthetic pathways have been proposed for trienoic fatty acids(FA) in 18: 3/16: 3 and 18: 3/18: 3 monogalactosyldiacylglycerol (MGDG) molecular species1. In the ‘prokaryotic’ pathway, 18: 1/16: 0 MGDG is synthesized within the chloroplast and desaturated in situ to form 18: 3/16: 3 MGDG. A ‘eukaryotic’ pathway involving microsomal phosphatidylcholine (PC) as substrate for desaturation of 18: 1 to 18: 2 provides the diglyceride precursor for 18: 3/18: 3 MGDG. After galactosylation, the MGDG is further desaturated in the chloroplast to form 18: 3/18: 3. We have used a recently identified mutant of Arabidopsis thaliana (L.) (‘JBl’) deficient in 18: 3,2 and secondly 4-chloro-5-dimethylamino-2-phenyl-3(2H)-pyridazinone (BASF 13-338, Sandoz 9785) which inhibits 18: 2 desaturation3 to obtain definitive evidence for the synthesis of 18: 3 via these different pathways.

Keywords

Biosynthetic Pathway Molecular Species Definitive Evidence Acetone Solution Plant Lipid 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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References

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    J. A. Browse, C. R. Somerville, and P. J. McCourt, in: W. Siegenthaler, W. Eichenberger, eds., Proc. 6th International Symposium on the Structure, Function and Metabolism of Plant Lipids. Elsevier/North Holland, Amsterdam, pp. 167–170 (1983).Google Scholar
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    J. B. St. John, Plant Physiol. 57: 38 (1976).CrossRefGoogle Scholar
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    H. A. Norman and J. B. St. John, Plant Physiol. 81: in press (1986).Google Scholar
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    H. A. Norman and J. B. St. John, J. Lipid Res., in press (1986).Google Scholar

Copyright information

© Plenum Press, New York 1987

Authors and Affiliations

  • Helen A. Norman
    • 1
  • Judith B. St. John
    • 1
  1. 1.ARS, Weed Science LaboratoryUSDABeltsvilleUSA

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