title: Parallel recordings of photosynthetic electron transport and K+-channel activity in single guard cells.
abstract: 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.
authors.affiliation: Julius-von-Sachs Institut für Biowissenschaften, Lehrstuhl für Molekulare Pflanzenphysiologie und Biophysik, Julius-von-Sachs-Platz 2, 97082 Würzburg, Germany.
authors.forename: Chang-Hyo
authors.initials: CH
authors.lastname: Goh
authors.forename: Petra
authors.initials: P
authors.lastname: Dietrich
authors.forename: Ralf
authors.initials: R
authors.lastname: Steinmeyer
authors.forename: Ulrich
authors.initials: U
authors.lastname: Schreiber
authors.forename: Hong-Gil
authors.initials: HG
authors.lastname: Nam
authors.forename: Rainer
authors.initials: R
authors.lastname: Hedrich
mesh_terms: D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D002734:Chlorophyll; D004058:Diffusion; D004579:Electron Transport / Q000528:radiation effects; D005453:Fluorescence; D017136:Ion Transport; D008027:Light; D018408:Patch-Clamp Techniques; D010710:Phosphates / Q000378:metabolism; D010788:Photosynthesis / Q000528:radiation effects; D011188:Potassium / Q000378:metabolism*; D015221:Potassium Channels / Q000378:metabolism*; D011523:Protoplasts / Q000166:cytology / Q000378:metabolism; D031307:Vicia faba / Q000166:cytology* / Q000378:metabolism* / Q000528:radiation effects
chemical_list: D010710:Phosphates; D015221:Potassium Channels; D002734:Chlorophyll; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D011188:Potassium