Effects of glycine on dark-and ligh-induced pulvinar movements and modifications of proton fluxes in the pulvinus of Mimosa pudica during glycine uptake.

Glycine (1-50 mM) increases the rate of the dark-induced (scotonastic) movements and decreases the amplitude and the rate of the light-induced (photonastic) movements of the secondary pulvini of Mimosa pudica leaves. The uptake of glycine is accompanied by a long-lasting dose-dependent increase in the alkalinity of the bathing medium of the excised pulvini. The data are in agreement with a H(+)-glycine co-transport mechanism within the pulvinar cells. Fusicoccin (50 μM), known to promote H(+)-K(+) exchange, antagonizes the effects of glycine on the movements and the alkalization of the bathing medium of the excised pulvini. The present results argue for the hypothesis that proton fluxes mediate the scotonastic and photonastic pulvinar movements.