Journal Article

Identification of K<sup>+</sup> Channels in the Plasma Membrane of Maize Subsidiary Cells

Ingrida Majore, Bettina Wilhelm and Irene Marten

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 43, issue 8, pages 844-852
Published in print August 2002 | ISSN: 0032-0781
Published online August 2002 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/pcp/pcf104
Identification of K+ Channels in the Plasma Membrane of Maize Subsidiary Cells

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  • Biochemistry
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The stomatal complex of Zea mays consists of two guard cells with the pore in between them and two flanking subsidiary cells. Both guard cells and subsidiary cells are important elements for stoma physiology because a well-coordinated transmembrane shuttle transport of potassium and chloride ions occurs between these cells during stomatal movement. To shed light upon the corresponding transport systems from subsidiary cells, subsidiary cell protoplasts were enzymatically isolated and in turn, analyzed with the patch-clamp technique. Thereby, two K+-selective channel types were identified in the plasma membrane of subsidiary cells. With regard to their voltage-dependent gating behavior, they may act as hyperpolarization-dependent K+ uptake and depolarization-activated K+ release channels during stomatal movement. Interestingly, the K+ channels from subsidiary cells and guard cells similarly responded to membrane voltage as well as to changes in the K+ gradient. Further, the inward- and outward-rectifying K+ current amplitude decreased upon a rise in the intracellular free Ca2+ level from 2 nM to the µM-range. The results indicate that the plasma membrane of subsidiary cells and guard cells has to be inversely polarized in order to achieve the anti-parallel direction of K+ fluxes between these cell types during stomatal movement.

Keywords: Keywords: K+ channels — Maize — Patch clamp — Stomatal complex — Subsidiary cell protoplasts.

Journal Article.  6607 words.  Illustrated.

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

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