Fluxes of Potassium and Changes in Malate within Epidermis of Commelina cyanea and their Relationships with Stomatal Aperture

Abstract

Stomatal apertures and concentrations of potassium, malate and sugars within the epidermis were measured during stomatal opening and closure; the location of K+ was also estimated by cobaltinitrite staining. The concentration of K+ in the epidermis as a whole did not change during stomatal opening and closure, but K+ migrated between epidermal and guard cells. Concentrations of sugars also remained constant. By contrast, there was a positive relationship between concentration of malate and aperture. These and other results emphasize an appreciable degree of isolation of the epidermis.