Abstract
We used the patch-clamp technique to examine the effect of temperature (13-36[deg]C) on the depolarization-activated K channels (KD channels) and on the hyperpolarization-activated channels (KH channels) in the plasma membrane of Vicia faba guard-cell protoplasts. The steady-state whole-cell conductance of both K channel types increased with temperature up to 20[deg]C. However, whereas the whole-cell conductance of the KH channels increased further and saturated at 28[deg]C, that of KD channels decreased at higher temperatures. The unitary conductance of both channel types increased with temperature like the rate of diffusion in water (temperature quotient of approximately 1.5), constituting the major contribution to the conductance increase in the whole cells. The mean number of available KH channels was not affected significantly by temperature, but the mean number of available KD channels increased significantly between 13 and 20[deg]C and declined drastically above 20[deg]C. This decrease and the reduced steady-state voltage-dependent probability of opening of the KD channels above 28[deg]C (because of a shift of voltage dependence by +21 mV) account for the depression of the whole-cell KD conductance at the higher temperatures. This may be a basic mechanism by which leaves of well-watered plants keep their stomata open during heat stress to promote cooling by transpiration.
Full Text
The Full Text of this article is available as a PDF (1.0 MB).
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Assmann S. M. Signal transduction in guard cells. Annu Rev Cell Biol. 1993;9:345–375. doi: 10.1146/annurev.cb.09.110193.002021. [DOI] [PubMed] [Google Scholar]
- Ding J. P., Pickard B. G. Modulation of mechanosensitive calcium-selective cation channels by temperature. Plant J. 1993 May;3(5):713–720. [PubMed] [Google Scholar]
- Dupont F. M. Effect of temperature on the plasma membrane and tonoplast ATPases of barley roots : comparison of results obtained with acridine orange and quinacrine. Plant Physiol. 1989 Apr;89(4):1401–1412. doi: 10.1104/pp.89.4.1401. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Fairley-Grenot K. A., Assmann S. M. Permeation of Ca2+ through K+ channels in the plasma membrane of Vicia faba guard cells. J Membr Biol. 1992 Jun;128(2):103–113. doi: 10.1007/BF00231883. [DOI] [PubMed] [Google Scholar]
- Froehner S. C. The submembrane machinery for nicotinic acetylcholine receptor clustering. J Cell Biol. 1991 Jul;114(1):1–7. doi: 10.1083/jcb.114.1.1. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Gilroy S., Read N. D., Trewavas A. J. Elevation of cytoplasmic calcium by caged calcium or caged inositol triphosphate initiates stomatal closure. Nature. 1990 Aug 23;346(6286):769–771. doi: 10.1038/346769a0. [DOI] [PubMed] [Google Scholar]
- Hamill O. P., Marty A., Neher E., Sakmann B., Sigworth F. J. Improved patch-clamp techniques for high-resolution current recording from cells and cell-free membrane patches. Pflugers Arch. 1981 Aug;391(2):85–100. doi: 10.1007/BF00656997. [DOI] [PubMed] [Google Scholar]
- Ilan N., Schwartz A., Moran N. External pH effects on the depolarization-activated K channels in guard cell protoplasts of Vicia faba. J Gen Physiol. 1994 May;103(5):807–831. doi: 10.1085/jgp.103.5.807. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Kruse T., Tallman G., Zeiger E. Isolation of Guard Cell Protoplasts from Mechanically Prepared Epidermis of Vicia faba Leaves. Plant Physiol. 1989 Aug;90(4):1382–1386. doi: 10.1104/pp.90.4.1382. [DOI] [PMC free article] [PubMed] [Google Scholar]
- McLarnon J. G., Hamman B. N., Tibbits G. F. Temperature dependence of unitary properties of an ATP-dependent potassium channel in cardiac myocytes. Biophys J. 1993 Nov;65(5):2013–2020. doi: 10.1016/S0006-3495(93)81243-8. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Rogers C., Sharpe P. J., Powell R. D., Spence R. D. High-temperature Disruption of Guard Cells of Vicia faba: EFFECT ON STOMATAL APERTURE. Plant Physiol. 1981 Feb;67(2):193–196. doi: 10.1104/pp.67.2.193. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Schroeder J. I. Quantitative analysis of outward rectifying K+ channel currents in guard cell protoplasts from Vicia faba. J Membr Biol. 1989 Mar;107(3):229–235. doi: 10.1007/BF01871938. [DOI] [PubMed] [Google Scholar]
- Wu W. H., Assmann S. M. A membrane-delimited pathway of G-protein regulation of the guard-cell inward K+ channel. Proc Natl Acad Sci U S A. 1994 Jul 5;91(14):6310–6314. doi: 10.1073/pnas.91.14.6310. [DOI] [PMC free article] [PubMed] [Google Scholar]