Cytosolic calcium oscillation may induce stomatal oscillation in Vicia faba

Whether guard cell cytosolic calcium ([Ca2+](cyt)) oscillation induced stomatal oscillation was investigated in Vicia faba leaf. Extracellular Ca2+, ABA and H2O2 treatments induced stomata to close in a dose- and time-dependent way. Both steady-state and rapid exchange treatments could first induce a steep decrease in stomatal aperture and then significantly induce stomatal oscillations at small apertures. Steady-state extracellular Ca2+ and ABA treatments caused obvious but small and irregular stomatal oscillations, and the oscillations lasted for shorter time, while steady-state H2O2 treatment induced no stomatal oscillation. Intriguingly, rapid exchange treatments of high [K+] buffer and high [Ca2+] buffer or high [ABA] buffer induced significant, strong, regular and longer time stomatal oscillations, while no oscillation occurred under H2O2 treatment in the same procedure. It was likely that [Ca2+](cyt) oscillations induced by extracellular Ca2+ and ABA Could induce stomatal oscillations and stomatal oscillations occurred at small apertures. (C) 2003 Elsevier Ireland Ltd. All rights reserved.