Abstract
The surface pH shift induced by active H+ excretion in corn (Zea mays L.) roots was estimated using acetic acid influx as a pH probe (H Sentenac, C Grignon 1987 Plant Physiol 84: 1367-1372). At constant bulk pH, buffering the medium strongly reduced the magnitude of the surface pH shift. This was used to study the effect of surface pH shift on H+ cotransports. In the absence of buffers, the surface pH shift increased with the bulk pH. Buffers decreased 32Pi influx and this effect was stronger at pH 7.2 than at pH 5.8, and stronger in the absence than in the presence of an inhibitor of the proton pump (vanadate). Buffers exerted a similar depressive and pH-dependent effect on net NO3− uptake. They hyperpolarized the cell membrane, and stimulated 86Rb+ influx, K+:H+ net exchange, and malate accumulation. These results are consistent with the hypothesis that H+ accumulation at the cell surface is effective in driving H+ reentry. We concluded that the surface pH shift due to proton pump activity is involved in the energetic coupling of H+ cotransports.
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Selected References
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- Lin W., Hanson J. B. Cell potentials, cell resistance, and proton fluxes in corn root tissue: effects of dithioerythritol. Plant Physiol. 1976 Sep;58(3):276–282. doi: 10.1104/pp.58.3.276. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Lin W. Potassium and Phosphate Uptake in Corn Roots: Further Evidence for an Electrogenic H/K Exchanger and an OH/Pi Antiporter. Plant Physiol. 1979 May;63(5):952–955. doi: 10.1104/pp.63.5.952. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Sentenac H., Grignon C. Effect of H Excretion on the Surface pH of Corn Root Cells Evaluated by Using Weak Acid Influx as a pH Probe. Plant Physiol. 1987 Aug;84(4):1367–1372. doi: 10.1104/pp.84.4.1367. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Sentenac H., Grignon C. Effect of pH on Orthophosphate Uptake by Corn Roots. Plant Physiol. 1985 Jan;77(1):136–141. doi: 10.1104/pp.77.1.136. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Thibaud J. B., Soler A., Grignon C. H and k electrogenic exchanges in corn roots. Plant Physiol. 1986 Jul;81(3):847–853. doi: 10.1104/pp.81.3.847. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Ullrich-Eberius C. I., Novacky A., Fischer E., Lüttge U. Relationship between Energy-dependent Phosphate Uptake and the Electrical Membrane Potential in Lemna gibba G1. Plant Physiol. 1981 Apr;67(4):797–801. doi: 10.1104/pp.67.4.797. [DOI] [PMC free article] [PubMed] [Google Scholar]