title: Cytosolic Ca(2+) Signals Enhance the Vacuolar Ion Conductivity of Bulging Arabidopsis Root Hair Cells.
abstract: Plant cell expansion depends on the uptake of solutes across the plasma membrane and their storage within the vacuole. In contrast to the well-studied plasma membrane, little is known about the regulation of ion transport at the vacuolar membrane. We therefore established an experimental approach to study vacuolar ion transport in intact Arabidopsis root cells, with multi-barreled microelectrodes. The subcellular position of electrodes was detected by imaging current-injected fluorescent dyes. Comparison of measurements with electrodes in the cytosol and vacuole revealed an average vacuolar membrane potential of -31 mV. Voltage clamp recordings of single vacuoles resolved the activity of voltage-independent and slowly deactivating channels. In bulging root hairs that express the Ca(2+) sensor R-GECO1, rapid elevation of the cytosolic Ca(2+) concentration was observed, after impalement with microelectrodes, or injection of the Ca(2+) chelator BAPTA. Elevation of the cytosolic Ca(2+) level stimulated the activity of voltage-independent channels in the vacuolar membrane. Likewise, the vacuolar ion conductance was enhanced during a sudden increase of the cytosolic Ca(2+) level in cells injected with fluorescent Ca(2+) indicator FURA-2. These data thus show that cytosolic Ca(2+) signals can rapidly activate vacuolar ion channels, which may prevent rupture of the vacuolar membrane, when facing mechanical forces.
authors.affiliation: State Key Laboratory of Plant Physiology and Biochemistry (SKLPPB), College of Biological Sciences, China Agricultural University, Beijing 100193, China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Molecular Plant Physiology and Biophysics, Julius-von-Sachs Institute for Biosciences, Biocenter, Würzburg University, Julius-von-Sachs-Platz 2, 97082 Würzburg, Germany.
authors.forename: Julian
authors.initials: J
authors.lastname: Dindas
authors.affiliation: Molecular Plant Physiology and Biophysics, Julius-von-Sachs Institute for Biosciences, Biocenter, Würzburg University, Julius-von-Sachs-Platz 2, 97082 Würzburg, Germany.
authors.forename: Florian
authors.initials: F
authors.lastname: Rienmüller
authors.affiliation: Centre for Organismal Studies, Developmental Biology of Plants, University of Heidelberg, Im Neuenheimer Feld 230, 69120 Heidelberg, Germany.
authors.forename: Melanie
authors.initials: M
authors.lastname: Krebs
authors.affiliation: Centre for Organismal Studies, Developmental Biology of Plants, University of Heidelberg, Im Neuenheimer Feld 230, 69120 Heidelberg, Germany.
authors.forename: Rainer
authors.initials: R
authors.lastname: Waadt
authors.affiliation: Centre for Organismal Studies, Developmental Biology of Plants, University of Heidelberg, Im Neuenheimer Feld 230, 69120 Heidelberg, Germany.
authors.forename: Karin
authors.initials: K
authors.lastname: Schumacher
authors.affiliation: State Key Laboratory of Plant Physiology and Biochemistry (SKLPPB), College of Biological Sciences, China Agricultural University, Beijing 100193, China.
authors.forename: Wei-Hua
authors.initials: WH
authors.lastname: Wu
authors.affiliation: Molecular Plant Physiology and Biophysics, Julius-von-Sachs Institute for Biosciences, Biocenter, Würzburg University, Julius-von-Sachs-Platz 2, 97082 Würzburg, Germany; College of Science, King Saud University (KSU), Riyadh, Saudi Arabia.
authors.forename: Rainer
authors.initials: R
authors.lastname: Hedrich
authors.affiliation: Molecular Plant Physiology and Biophysics, Julius-von-Sachs Institute for Biosciences, Biocenter, Würzburg University, Julius-von-Sachs-Platz 2, 97082 Würzburg, Germany. Electronic address: roelfsema@botanik.uni-wuerzburg.de.
authors.forename: M Rob G
authors.initials: MR
authors.lastname: Roelfsema
mesh_terms: D017360:Arabidopsis / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling; D003600:Cytosol / Q000378:metabolism; D007473:Ion Channels / Q000378:metabolism*; D008564:Membrane Potentials; D008839:Microelectrodes; D018517:Plant Roots / Q000378:metabolism; D014617:Vacuoles / Q000378:metabolism
chemical_list: D007473:Ion Channels; D002118:Calcium
keywords: Arabidopsis; calcium signaling/transport; electrophysiology; fluorescence imaging; ion channels; vacuolar membrane