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A postulated role for calcium oxalate in the regulation of calcium ions in the vicinity of stomatal guard cells.

Ruiz, L. P. and Mansfield, T. A. (1994) A postulated role for calcium oxalate in the regulation of calcium ions in the vicinity of stomatal guard cells. New Phytologist, 127 (3). pp. 473-481. ISSN 1469-8137

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Abstract

Calcium ions are known to play an important part in signal transduction in stomatal guard cells. In Cummelina communis L., stomatal opening in isolated epidermis is strongly inhibited if the calcium concentration in the incubation medium is 0.1 mol mol m−3 or greater, It can be assumed that in the intact leaf, the apoplastic concentration of free calcium in the vicinity of the guard cells must be kept below this level if interference with stomatal functioning is to be avoided. When C. communis was grown with 15 mol m−3 calcium in the rhizosphere, the concentration of free calcium in the xylem sap in the shoot was found to be 3.76 mol m−3. A mechanism is clearly needed for reducing this concentration as the sap traverses the apoplast between the xylem and the stomatal guard cells. Evidence is presented here that the deposition of calcium oxalate in cells of the leaf achieves the necessary regulation. The protective role of the six specialized subsidiary cells in this species appears to be specially important. It is suggested that the regulation of apoplastic free calcium may take an important contribution to the effective stomatal control of gas exchange.

Item Type: Article
Journal or Publication Title: New Phytologist
Uncontrolled Keywords: Calcium oxalate • stomata • guard cells • subsidiary cells • calcium ions
Subjects: G Geography. Anthropology. Recreation > GE Environmental Sciences
Departments: Faculty of Science and Technology > Lancaster Environment Centre
ID Code: 22518
Deposited By: ep_ss_importer
Deposited On: 27 Jan 2009 14:06
Refereed?: Yes
Published?: Published
Last Modified: 26 Jul 2012 16:02
Identification Number:
URI: http://eprints.lancs.ac.uk/id/eprint/22518

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