Journal Article

ABA Regulation of K<sup>+</sup>-Permeable Channels in Maize Subsidiary Cells

Thomas Wolf, Tobias Heidelmann and Irene Marten

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 47, issue 10, pages 1372-1380
Published in print October 2006 | ISSN: 0032-0781
Published online October 2006 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/pcp/pcl007
ABA Regulation of K+-Permeable Channels in Maize Subsidiary Cells

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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.

Keywords: ABA — Ca2+ — K+-permeable channels —pH — subsidiary cells — Zea mays.

Journal Article.  5752 words.  Illustrated.

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

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