Abstract
Because of their importance for nutrition, a method was developed to patch xylem contact cells in leaves of Vicia faba and maize. Since the lignification of older cells was a major obstacle for isolating protoplasts which could be patched, only young leaves (fourth fully developed leaf) were used. An important step in the isolation of these cells was the infiltration of the leaves and their exposure to enzymes for several hours, allowing mesophyll cells to be removed whilst having most of the xylem contact cells attached to the xylem. Channel activity in cell-attached mode or in excised patches could only be observed if an internal coating of sigmacote was used to block diffusion ions out of the pipette glass. Two different types of K+ channels were identified by measuring the reversal potential at different concentrations of KCl. One channel (SC) had a symmetric IV curve with a high probability of remaining open, irrespective of membrane potential; the other channel was an inward rectifier. The symmetical channel could be blocked weakly by Na+ but it was permeable to \({\text{NH}}_{{\text{4}}^{\text{ + }} } \).
Similar content being viewed by others
References
Albertsen A and Hansen U P 1994 Estimation of kinetic rate constants from multi-channel recordings by a direct fit of the time series. Biophys. J. 67, 1393-1403.
Copello J, Simon B, Segal Y, Wehner F, Ramanujam F, Sadagopa V M, Alcock N and Reuss L 1991 Ba2+release from soda glass modifies single maxi K+channel activity in patch clamp experiments. Biophys. J. 60, 931-941.
Draber S and Hansen U P 1994 Fast single-channel measurements resolve the blocking effect of Cs+on the K+channel. Biophys. J. 67, 120-127.
Fairley K A and Walker N A 1989 Patch clamping corn protoplasts-gigaseal frequency is not improved by Congo Red inhibition of cell wall regencration. Protoplasma 153, 111-116.
Hansen U P, Albertsen A, Moldaenke C, Draber S and Schultze R 1995 Detecting events in signals from sensors: the Hinkley-detector is the answer. Sensors and Materials 7, 289-300.
Hansen U P, Keunecke M and Blunck R 1997 Gating and permeation models of plant channels. J. Exp. Bot. 48, 365-382.
Hedrich R and Schroeder J I 1989 The physiology of ion channels and electrogenic pumps in higher plants. Annu. Rev. Plant Physiol. 40, 539-569.
Jeschke W D, Wolf O and Hartung W 1992 Effect of NaCl salinity on flows and partitioning of C, N, and mineral ions in whole plants of white lupin, Lupinus albusL. J. Exp. Bot. 43,251, 777-788.
Kim H, Coté G G and Crain R 1993 Potassium channels in Samanea samanprotoplasts controlled by a biological clock. Science 260, 960-962.
Matsumoto H and Chung G C 1988 Increase in proton-transport activity of tonoplast vesicles as an adaptive response of barley roots to NaCl stress. Plant Cell Physiol. 29, 1133-40.
McDougall, Gordon J H, Steward D and Morrison I M 1994 Cell wall bound oxidases from tobacco (Nicotina tabacum) xylem participate in lignin formation. Planta 194, 9-14.
Sanders D, Hansen U P, Gradman D and Slayman C L 1984 Generalized kinetic analysis of ion-driven cotransport systems: a unified interpretation of selective ionic effects on Michaelis parameters. J. Membrane Biol. 77, 123-152.
Schroeder J I, Raschke K and Neher E 1987 Voltage-dependence of K+channels in guard cell protoplasts. Proc. Natl. Acad. Sci. (USA) 84, 4108-4112.
Schroeder J I, Ward J M and Gassmann W 1994 Perspectives on the physiology and structure of inward-rectifying K+channels in higher plants: Biophysical implications for K+uptake. Annu. Rev. Biophys. Biomol. Struct. 23, 441-447.
Schultze R and Draber S 1993 A nonlinear filter algorithm for detection of jumps in patch clamp data. J. Membrane Biol. 132, 41-52.
Spalding E, Slayman C L, Goldsmith M H M, Gradmann D and Bertl A 1992 Ion channels in Arabidopsisplasma membrane. Transport characteristics and involvement of light-induced voltage changes. Plant Physiol. 99 96-102.
Wegner L H and Raschke K 1994 Ion channels in the xylem parenchyma of barley roots. A procedure to isolate protoplasts from this tissue and a patch-clamp exploration of salt passageways into xylem vessels. Plant Physiol. 105, 343-357.
Wegner L H, De Boer A H and Raschke K 1995 Properties of the K+inward rectifier in the plasma membrane of xylem parenchyma cells from barley roots: effects of TEA+, Ca2+, Ba2+and La3+. J. Membrane Biol. 142, 363-379.
Wilson T P, Canny M J and McCully M E 1991 Leaf teeth, transpiration and the retrieval of apoplastic solutes in balsam poplar. Physiol. Plant. 83, 225-232.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Keunecke, M., Sutter, J., Sattelmacher, B. et al. Isolation and patch clamp measurements of xylem contact cells for the study of their role in the exchange between apoplast and symplast of leaves. Plant and Soil 196, 239–244 (1997). https://doi.org/10.1023/A:1004206208968
Issue Date:
DOI: https://doi.org/10.1023/A:1004206208968