Parallel recordings of photosynthetic electron transport and K+-channel activity in single guard cells

Authors

  • Chang-Hyo Goh,

    1. Julius-von-Sachs Institut für Biowissenschaften, Lehrstuhl für Molekulare Pflanzenphysiologie und Biophysik, Julius-von-Sachs-Platz 2, 97082 Würzburg, Germany, and
    2. Division of Molecular and Life Science, Pohang University of Science and Technology, Pohang 790-784, Korea
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  • Petra Dietrich,

    1. Julius-von-Sachs Institut für Biowissenschaften, Lehrstuhl für Molekulare Pflanzenphysiologie und Biophysik, Julius-von-Sachs-Platz 2, 97082 Würzburg, Germany, and
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  • Ralf Steinmeyer,

    1. Julius-von-Sachs Institut für Biowissenschaften, Lehrstuhl für Molekulare Pflanzenphysiologie und Biophysik, Julius-von-Sachs-Platz 2, 97082 Würzburg, Germany, and
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  • Ulrich Schreiber,

    1. Julius-von-Sachs Institut für Biowissenschaften, Lehrstuhl für Molekulare Pflanzenphysiologie und Biophysik, Julius-von-Sachs-Platz 2, 97082 Würzburg, Germany, and
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  • Hong-Gil Nam,

    1. Julius-von-Sachs Institut für Biowissenschaften, Lehrstuhl für Molekulare Pflanzenphysiologie und Biophysik, Julius-von-Sachs-Platz 2, 97082 Würzburg, Germany, and
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  • Rainer Hedrich

    Corresponding author
    1. Julius-von-Sachs Institut für Biowissenschaften, Lehrstuhl für Molekulare Pflanzenphysiologie und Biophysik, Julius-von-Sachs-Platz 2, 97082 Würzburg, Germany, and
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* For correspondence (e-mail hedrich@botanik.uni-wuerzburg.de).

Summary

Stomata open in response to red and blue light. Red light-induced stomatal movement is mediated by guard cell chloroplasts and related to K+-uptake into these motor cells. We have combined a new type of microchlorophyll fluorometer with the patch–clamp technique for parallel studies of the photosynthetic electron transport and activity of plasma membrane K+ channels in single guard cell protoplast. In the whole-cell configuration and presence of ATP in the patch-pipette, the activity of the K+-uptake channels remained constant throughout the course of an experiment (up to 30 min) while photosynthetic activity declined to about 50%. In the absence of ATP inward K+ currents declined in a time-dependent manner. Under these ATP-free conditions, photosynthetic electron transport was completely blocked within 8 min. ADP together with orthophosphate was able to prevent inhibition of photosynthetic electron transport and run-down of K+-channel activity. The results demonstrate that the combination of these two techniques is suited to directly study cytosolic factors as common regulators of photosynthesis and plasma membrane transport within a single-cell.

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