Plant and Cell Physiology Advance Access originally published online on September 14, 2006
Plant and Cell Physiology 2006 47(10):1372-1380; doi:10.1093/pcp/pcl007
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ABA Regulation of K+-Permeable Channels in Maize Subsidiary Cells
University of Wuerzburg, Molecular Plant Physiology and Biophysics, Julius-von-Sachs Institute for Bioscience, Julius-von-Sachs-Platz 2, D-97082 Wuerzburg, Germany
* Corresponding author: E-mail, marten{at}botanik.uni-wuerzburg.de; Fax, +49-931-8886158.
An antiparallel-directed potassium transport between subsidiary cells and guard cells which form the graminean stomatal complex has been proposed to drive stomatal movements in maize. To gain insights into the coordinated shuttling of K+ ions between these cell types during stomatal closure, the effect of ABA on the time-dependent K+ uptake and K+ release channels as well as on the instantaneously activating non-selective cation channels (MgC) was examined in subsidiary cells. Patch-clamp studies revealed that ABA did not affect the MgC channels but differentially regulated the time-dependent K+ channels. ABA caused a pronounced rise in time-dependent outward-rectifying K+ currents (Kout) at alkaline pH and decreased inward-rectifying K+ currents (Kin) in a Ca2+-dependent manner. Our results show that the ABA-induced changes in time-dependent Kin and Kout currents from subsidiary cells are very similar to those previously described for guard cells. Thus, the direction of K+ transport in subsidiary cells and guard cells during ABA-induced closure does not seem to be grounded solely on the cell type-specific ABA regulation of K+ channels.
1 These authors contributed equally to this work.
(Received August 16, 2006; Accepted August 27, 2006)
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