Phytotoxic activity of middle-chain fatty acids II: peroxidation and membrane effects
Abstract
Pelargonic acid (PA), an aliphatic 9-carbon monocarboxylic acid, is a phytotoxic burn-down compound. In the light peroxidizing activity can be measured as ethane and propane formation with cress or tobacco seedlings. This effect is strong at low pH (4–5), and saturated acids with 9–10 carbon atoms represent the optimum chain length. Methyl or ethyl esters are inactive, and safeners have no influence. In contrast to the peroxidative herbicides like acifluorfen methyl neither photosynthesis nor protoporphyrin IX is involved, although peroxidation requires light. Chlorophyll is necessary since etiolated seedlings show little peroxidation. Singlet oxygen quenchers like eugenol markedly reduce peroxidation. Membrane leakage of a similar rate is observed in light as well as in darkness. PA was described as a penetration enhancer intercalating with membranes. Our data corroborate that conclusion. Accordingly, the herbicidal mode of action of pelargonic acid is due first to membrane leakage in dark or light and second to peroxidation driven by radicals originating in the light by sensitized chlorophyll displaced from the thylakoids.
- Publication:
-
Pesticide Biochemistry and Physiology
- Pub Date:
- January 2004
- DOI:
- Bibcode:
- 2004PBioP..80..151L
- Keywords:
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- Pelargonic acid;
- Peroxidation;
- Membrane leakage;
- Membrane intercalation;
- Ethane/propane formation;
- Singlet oxygen