Skip to main content
NCBI home page
Plant Physiology logoLink to Plant Physiology
. 1991 Apr;95(4):1063–1069. doi: 10.1104/pp.95.4.1063

Effects of Diclofop and Diclofop-Methyl on Membrane Potentials in Roots of Intact Oat, Maize, and Pea Seedlings

Joseph M DiTomaso 1,2,3,4, Patrick H Brown 1,2,3,4, Amy E Stowe 1,2,3,4, Dean L Linscott 1,2,3,4, Leon V Kochian 1,2,3,4
PMCID: PMC1077652  PMID: 16668091

Abstract

Growth and electrophysiological studies in roots of intact diclofop-methyl susceptible and resistant seedlings were conducted to test the hypothesis that the herbicide acts primarily as a proton ionophore. The ester formulation of diclofop, at 0.2 micromolar, completely inhibited root growth in herbicide-susceptible oat (Avena sativa L.) after a 96 hour treatment, but induced only a delayed transient depolarization of the membrane potential in oat root cortical cells. Root growth in susceptible maize (Zea mays L.) seedlings was dramatically reduced by exposure to 0.8 micromolar diclofop-methyl, while the same diclofop-methyl exposure hyperpolarized the membrane potential within 48 hours after treatment. Furthermore, exposure of maize roots to the protonophore, carbonyl cyanide m-chlorophenylhydrazone (CCCP) (50 nanomolar), inhibited growth by only 31%, 96 hours after treatment, while the same CCCP exposure depolarized the resting potential by an average of 32 millivolts. Thus, the protonophore hypothesis cannot account for a differential membrane response to phytotoxic levels of diclofop-methyl in two susceptible species. From the results of others, much of the evidence to support the protonophore hypothesis was obtained using high concentrations of diclofop acid (100 micromolar). At a similar concentration, we also report a rapid (3 minute) diclofop-induced depolarization of the membrane potential in roots of susceptible oat and maize, moderately tolerant barley (Hordeum vulgare L.), and resistant pea (Pisum sativum L.) seedlings. Moreover, 100 micromolar diclofop acid inhibited growth in excised cultured pea roots. In contrast, 100 micromolar diclofop-methyl did not inhibit root growth. Since the membrane response to 100 micromolar diclofop acid does not correspond to differential herbicide sensitivity under field conditions, results obtained with very high levels of diclofop acid are probably physiologically irrelevant. The results of this study suggest that the effect of diclofop-methyl on the membrane potentials of susceptible species is probably unrelated to the primary inhibitory effect of the herbicide on plant growth.

Full text

PDF
1063

Selected References

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

  1. Ditomaso J. M., Shaff J. E., Kochian L. V. Putrescine-induced wounding and its effects on membrane integrity and ion transport processes in roots of intact corn seedlings. Plant Physiol. 1989 Jul;90(3):988–995. doi: 10.1104/pp.90.3.988. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Fett W. F., Dunn M. F. Exopolysaccharides Produced by Phytopathogenic Pseudomonas syringae Pathovars in Infected Leaves of Susceptible Hosts. Plant Physiol. 1989 Jan;89(1):5–9. doi: 10.1104/pp.89.1.5. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Jachetta J. J., Appleby A. P., Boersma L. Apoplastic and symplastic pathways of atrazine and glyphosate transport in shoots of seedling sunflower. Plant Physiol. 1986 Dec;82(4):1000–1007. doi: 10.1104/pp.82.4.1000. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Kochian L. V., Lucas W. J. Potassium Transport in Corn Roots : III. Perturbation by Exogenous NADH and Ferricyanide. Plant Physiol. 1985 Feb;77(2):429–436. doi: 10.1104/pp.77.2.429. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Kochian L. V., Shaff J. E., Lucas W. J. High affinity k uptake in maize roots: a lack of coupling with h efflux. Plant Physiol. 1989 Nov;91(3):1202–1211. doi: 10.1104/pp.91.3.1202. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. 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]
  7. Parker W. B., Marshall L. C., Burton J. D., Somers D. A., Wyse D. L., Gronwald J. W., Gengenbach B. G. Dominant mutations causing alterations in acetyl-coenzyme A carboxylase confer tolerance to cyclohexanedione and aryloxyphenoxypropionate herbicides in maize. Proc Natl Acad Sci U S A. 1990 Sep;87(18):7175–7179. doi: 10.1073/pnas.87.18.7175. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Parker W. B., Somers D. A., Wyse D. L., Keith R. A., Burton J. D., Gronwald J. W., Gengenbach B. G. Selection and characterization of sethoxydim- tolerant maize tissue cultures. Plant Physiol. 1990 Apr;92(4):1220–1225. doi: 10.1104/pp.92.4.1220. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Ratterman D. M., Balke N. E. Diclofop-methyl increases the proton permeability of isolated oat-root tonoplast. Plant Physiol. 1989 Oct;91(2):756–765. doi: 10.1104/pp.91.2.756. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Rendina A. R., Felts J. M., Beaudoin J. D., Craig-Kennard A. C., Look L. L., Paraskos S. L., Hagenah J. A. Kinetic characterization, stereoselectivity, and species selectivity of the inhibition of plant acetyl-CoA carboxylase by the aryloxyphenoxypropionic acid grass herbicides. Arch Biochem Biophys. 1988 Aug 15;265(1):219–225. doi: 10.1016/0003-9861(88)90387-6. [DOI] [PubMed] [Google Scholar]
  11. 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]
  12. Wright J. P., Shimabukuro R. H. Effects of diclofop and diclofop-methyl on the membrane potentials of wheat and oat coleoptiles. Plant Physiol. 1987 Sep;85(1):188–193. doi: 10.1104/pp.85.1.188. [DOI] [PMC free article] [PubMed] [Google Scholar]

Articles from Plant Physiology are provided here courtesy of Oxford University Press

RESOURCES