INHIBITION AND UNCOUPLING OF ELECTRON TRANSPORT IN ISOLATED CHLOROPLASTS BY THE HERBICIDE 4,6-DINITRO-O-CRESOL |
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| Authors: | J. J. S. van Rensen W. van der Vet W. P. A. van Vliet |
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| Affiliation: | Laboratory of Plant Physiological Research, Agricultural University, Wageningen, The Netherlands |
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| Abstract: | Abstract— Dinitrophenols are known to affect photosynthetic electron transfer. It is shown that the widely used herbicide 4,6-dinitro-o-cresol is a potent inhibitor of the Hill reaction in isolated chloroplasts. By studying different parts of Photosystem II dependent electron transport it is indicated that this herbicide inhibits at the same site as 3-(3.4-dichlorophenyl)-l,1-dimethylurea.
However, the Photosystem I dependent Mehler reaction ascorbate/dichlorophenolindophenol→ diquat is stimulated at higher concentrations of the herbicide. This stimulation does not occur when an uncoupler is added to the reaction medium. There is also no stimulation of the ascorbatep-tetra-methyl-p-phenylene diamine → diquat Mehler reaction. This suggests that 4,6-dinitro-o-cresol uncouples electron transport in the Photosystem I dependent Mehler reaction, when added at higher |
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