Mode of Inhibition of Photosynthetic Electron Transport by Substituted Diphenylethers

Herbicides, Photosynthesis, Diphenylether, Inhibitors, Plastoquinone Several substituted diphenylethers were found to be effective inhibitors of photosynthetic electron flow in isolated thylakoid membranes from spinach chloroplasts. Their site of inhibition was localized with artificial acceptor and donor systems. The phenylether of an alkyl substituted nitrophenol is primarely inhibiting electron flow after plastoquinone function whereas a dinitrophenylether of a phenyl substituted nitrophenol is inhibiting before plastoquinone function. Therefore certain diphenylethers interfere with plastoquinone function at the oxidation or reduction site, depending on the substitution.