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Parallel recordings of photosynthetic electron transport and K + ‐channel activity in single guard cells
Author(s) -
Goh ChangHyo,
Dietrich Petra,
Steinmeyer Ralf,
Schreiber Ulrich,
Nam HongGil,
Hedrich Rainer
Publication year - 2002
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1046/j.1365-313x.2002.01451.x
Subject(s) - guard cell , electron transport chain , photosynthesis , biophysics , ion transporter , pipette , patch clamp , chemistry , chloroplast , protoplast , membrane , biochemistry , biology , receptor , gene
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 ortho phosphate 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.