Ca leads to the suppression of stomatal opening.

 

Calcium inhibits ion-stimulated stomatal opening in epidermal strips of Commelina communis L.

by Inoue H., Katoh Y. (1987)

in Journal of Experimental Botany 38, 142–149. –

CrossRef | CAS |

http://jxb.oxfordjournals.org/content/38/1/142

Abstract

Ca²⁺ suppressed both the ion-stimulated stomatal opening and H⁺extrusion of pre-illuminated epidermal strips isolated from Commelina communis L.

In the absence of Ca²⁺, the rate of H⁺ release was 18 nmol H⁺ cm^–2 h^–1 per epidermal strip unit area in 150 mol m^–3 KCL at pH 7·4. Half-maximum inhibition of stomatal opening was observed with 220 mmol m^–3 of Ca²⁺.

The hexavalent dye, ruthenium red, showed concentration-dependent prevention of the inhibition by Ca²⁺ of the ion-stimulated stomatal opening. The effect of ruthenium red was non-competitive, and the K₁ for the calcium inhibition was found to be 3·6 mmol m^–3. The calcium inhibition of H⁺ extrusion was also prevented by ruthenium red.

These results suggest that Ca²⁺ inhibits the activity of electrogenic H⁺ translocating ATPase of the guard cell plasma membrane and leads to the suppression of stomatal opening.