Vanadate inhibits blue light-stimulated swelling of vicia guard cell protoplasts

Amodeo, G.; Srivastava, A.; Zeiger, E.

doi:10.1104/pp.100.3.1567

When supplied under low chloride concentrations, vanadate inhibits the blue light-stimulated swelling of Vicia faba L. guard cell protoplasts in a dose-dependent fashion. The volume of guard cell protoplasts incubated in 10 mM K-imino-diacetic acid, 0.4 M mannitol, and 1 mM CaCl2 remained essentially constant under 1000 micromoles m-2 s-1 red light, but increased an average of 27% after 8 min of the addition of 50 micromoles m-2 s-1 blue light to the background red light. At 500 micromolar, vanadate completely inhibits the response to blue light. Vanadate also inhibits the swelling of guard cell protoplasts stimulated by the H+-ATPase agonist fusicoccin. The vanadate sensitivity of the blue light-stimulated swelling implicates a proton-pumping ATPase as a component of the sensory transduction of blue light in guard cells.