Abstract
Previous work has shown that undissociated 2,4-dinitrophenol (DNP) both increases the permeability of roots to ions and alters the membrane lipids of barley roots. Anionic DNP is the main entrant form but has no effect on permeability or on the membrane lipids. The amount of anionic DNP taken up by the roots is sufficient, that were it in free solution in the cytoplasm, the DNP would uncouple oxidative phosphorylation, and thereby inhibit ATP synthesis. The present work was undertaken to assess whether DNP alters ATP levels when it is taken up by barley roots. 31P nuclear magnetic resonance spectra were used to monitor, in vivo, levels of ATP, cytoplasmic phosphate, vacuolar phosphate, and other phosphate compounds in barley roots in the presence of 10 micromolar DNP at pH 5 and pH 7. The spectra indicate that no change in the level of ATP or the cytoplasmic pH occurred in the roots in the presence of DNP for as long as 20 hours. Thus, the effects of undissociated DNP are effects directly on the root membranes and do not involve inhibition of ATP synthesis. Furthermore, the results explain why anionic DNP has no effect on ion uptake and accumulation.
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Selected References
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- Baddeley M. S., Hanson J. B. Uncoupling of energy-linked functions of corn mitochondria by linoleic Acid and monomethyldecenylsuccinic Acid. Plant Physiol. 1967 Dec;42(12):1702–1710. doi: 10.1104/pp.42.12.1702. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Jackson P. C. Differences between Effects of Undissociated and Anionic 2,4-Dinitrophenol on Permeability of Barley Roots. Plant Physiol. 1982 Nov;70(5):1373–1379. doi: 10.1104/pp.70.5.1373. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Jackson P. C., Hendricks S. B., Vasta B. M. Phosphorylation by Barley Root Mitochondria & Phosphate Absorption by Barley Roots. Plant Physiol. 1962 Jan;37(1):8–17. doi: 10.1104/pp.37.1.8. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Jackson P. C., John J. B. Effects of 2,4-dinitrophenol on membrane lipids of roots. Plant Physiol. 1982 Sep;70(3):858–862. doi: 10.1104/pp.70.3.858. [DOI] [PMC free article] [PubMed] [Google Scholar]
- MITCHELL P. Coupling of phosphorylation to electron and hydrogen transfer by a chemi-osmotic type of mechanism. Nature. 1961 Jul 8;191:144–148. doi: 10.1038/191144a0. [DOI] [PubMed] [Google Scholar]
- Pfeffer P. E., Tu S. I., Gerasimowicz W. V., Cavanaugh J. R. In VivoP NMR Studies of Corn Root Tissue and Its Uptake of Toxic Metals. Plant Physiol. 1986 Jan;80(1):77–84. doi: 10.1104/pp.80.1.77. [DOI] [PMC free article] [PubMed] [Google Scholar]