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. 1987 Sep;85(1):188–193. doi: 10.1104/pp.85.1.188

Effects of Diclofop and Diclofop-Methyl on the Membrane Potentials of Wheat and Oat Coleoptiles

John P Wright 1,2,1, Richard H Shimabukuro 1,2
PMCID: PMC1054227  PMID: 16665655

Abstract

Electrophysiological measurements were made on the mesophyll cells of wheat (Triticum aestivum L. cv Waldron) and oat (Avena sativa L. cv Garry) coleoptiles treated either with the herbicide diclofop-methyl (methyl 2-(4-(2′,4′-dichlorophenoxy)phenoxy)propanoate), or it's primary metabolite diclofop, (2-(4-(2′,4′-dichlorophenoxy)phenoxy)-propanoic acid). Application of a 100 micromolar solution of diclofop-methyl to wheat coleoptiles had little or no effect on the membrane potential (EM), however in oat, EM slowly depolarized to the diffusion potential (ED). At pH 5.7, 100 micromolar diclofop rapidly abolished the electrogenic component of the membrane potential in both oat and wheat coleoptiles with half-times of 5 to 10 minutes and 15 to 20 minutes, respectively. The concentrations giving half-maximal depolarizations in wheat were 20 to 30 micromolar compared to 10 to 20 micromolar in oat. The depolarizing response was not due to a general increase in membrane permeability as judged from the EM's response to changes in K+, Na+, Cl−, and SO42−, before and after treatment with diclofop and from its response to KCN treatment. In both plants, diclofop increased the membrane permeability to protons, making the EM strongly dependent upon the external pH in the range of pH 5.5 to pH 8.5. The effects of diclofop can best be explained by its action as a specific proton ionophore that shuttles protons across the plasmalemma. The rapidity of the cell's response to both diclofop-methyl (15-20 minutes) and diclofop (2-5 minutes) makes the ionophoric activity a likely candidate for the earliest herbicidal event exhibited by these compounds.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Lucas W. J., Wilson C., Wright J. P. Perturbation of Chara Plasmalemma Transport Function by 2[4(2',4'-Dichlorophenoxy)phenoxy]propionic Acid. Plant Physiol. 1984 Jan;74(1):61–66. doi: 10.1104/pp.74.1.61. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Pierce W. S., Higinbotham N. Compartments and Fluxes of K, NA, and CL in Avena Coleoptile Cells. Plant Physiol. 1970 Nov;46(5):666–673. doi: 10.1104/pp.46.5.666. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Shimabukuro R. H., Walsh W. C., Hoerauf R. A. Metabolism and selectivity of diclofop-methyl in wild oat and wheat. J Agric Food Chem. 1979 May-Jun;27(3):615–623. doi: 10.1021/jf60223a008. [DOI] [PubMed] [Google Scholar]
  4. Shimabukuro R. H., Walsh W. C., Hoerauf R. A. Reciprocal Antagonism between the Herbicides, Diclofop-Methyl and 2,4-D, in Corn and Soybean Tissue Culture. Plant Physiol. 1986 Mar;80(3):612–617. doi: 10.1104/pp.80.3.612. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Sze H. Nigericin-stimulated ATPase activity in microsomal vesicles of tobacco callus. Proc Natl Acad Sci U S A. 1980 Oct;77(10):5904–5908. doi: 10.1073/pnas.77.10.5904. [DOI] [PMC free article] [PubMed] [Google Scholar]

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