Elevation of cytoplasmic calcium by caged calcium or caged inositol trisphosphate initiates stomatal closure

Stomatal pores at the leaf surface regulate water loss during transpiration and CO2 uptake for photosynthesis through changes in the turgor of the surrounding guard cells. Such regulation occurs in response to a wide range of environmental stimuli (such as light, CO2 level and abscisic acid). These...

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Bibliographic Details
Published in:Nature (London) 1990-08, Vol.346 (6286), p.769-771
Main Authors: Gilroy, S, Read, N.D, Trewavas, A.J
Format: Article
Language:English
Subjects:
Abscisic acid
Apertures
Calcium
Calcium (intracellular)
Calcium imaging
Calcium influx
Calcium ions
Calcium mobilization
Commelina communis
cytoplasm
Cytosol
Environmental effects
Fluo-3
Fluorescence
Guard cells
Humanities and Social Sciences
Inositol 1,4,5-trisphosphate receptors
inositol phosphates
letter
Light effects
multidisciplinary
Photosynthesis
Science
Science (multidisciplinary)
Second messengers
Stomata
stomatal movement
Transpiration
Turgor
Ultraviolet radiation
Water loss
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Summary:Stomatal pores at the leaf surface regulate water loss during transpiration and CO2 uptake for photosynthesis through changes in the turgor of the surrounding guard cells. Such regulation occurs in response to a wide range of environmental stimuli (such as light, CO2 level and abscisic acid). These are thought to be transduced through changes in cytosolic calcium levels, and several treatments causing stomatal closure are accompanied by increases in cytosolic Ca2+ (ref. 4), probably from mobilization of intracellular Ca2+ stores. We report here the use of the fluorescent Ca2+ indicator Fluo-3 (refs 5, 6) to follow changes in stomatal aperture and cytoplasmic Ca2+ concentration as Ca2+ or inositol 1,4,5-haemoproteins. To date only three have been established with certainty. They are bis-histidine, as in mammalian cytochrome b, (ref. 10), methionine-histidine, typified by cytochrome c (ref. 11) and lysine-histidine, recently recognized by spectroscopic methods in cytochrome f (ref. 12). Here we report the electron paramagnetic resonance and near infrared magnetic circular dichroism spectra of the oxidized state of Ps. aeruginosa bacterioferritin which enable the axial ligands to be identified as the thioether side chains of two methionine residues, a ligation scheme not previously reported for haem in any protein.
ISSN:0028-0836
1476-4687
DOI:10.1038/346769a0