| Abstract: | The effects of light/dark on cation fluxes in isolated guardcells of Commelina communis L. have been studied, using 86RbCland 22NaCl. Transfer to the dark has no effect on 86Rb influx,but produces a marked transient stimulation of 86Rb efflux,similar to that seen previously on adding ABA. The 86Rb effluxfalls on return to light only during the period of stimulatedflux; after the transient, return to light has no effect onefflux. The ability to produce this transient stimulation ontransfer to the dark is recovered in a subsequent light period.In general, in Na-loaded cells, the stimulated efflux is notseen. and the cells do not close in the dark. The results arenot consistent with a simple permeability or potential change,but suggest a specific ion excretion activated by the transferto the dark. Key words: Commelina communis L., Light/dark effects, Cation flux, Guard cells |
