Stomatal responses to ABA and IAA in isolated epidermal strips of Vicia faba L.

Abstract

Epidermal strips from well-watered faba-bean plants were subjected to a range of abscisic acid (ABA) and indolyl-3-acetic acid (IAA) concentrations (10-5 to 1 mM) in the presence or absence of CO2 in light or dark. ABA had inhibitory effect on abaxial stomatal apertures in all the concentrations studied and retained them closed even after addition of KCl (SO and 100 mM) to the incubation medium. It also influenced stomatal responses to CO2. In the presence of CO2 apertures were greater than in its absence in light as well as in darkness. This relationship remained unchanged also after addition of KCl. The action of ABA inhibited accumulation of potassium in the guard cells. IAA stimulated stomatal opening and its effect was quite opposite to ABA; in the presence of CO2 the apertures were smaller than in its absence. IAA, however, was able to inhibit the closing effect of darkness, CO2, and ABA, and stimulated potassium accumulation in the guard cells. Simultaneous action of ABA+IAA manifested effects of both substances. © 1992 Institute of Experimental Botany.