Peptides derived from the auxin binding protein elevate Ca2+ and pH in stomatal guard cells of Vicia faba: a confocal fluorescence ratio imaging study
Fricker, M.D.; White, N.S.; Thiel, G.; Millner, P.; Blatt, M.R.
Symposia of the Society for Experimental Biology 48: 215-228
1994
ISSN/ISBN: 0081-1386 PMID: 7597645 Document Number: 436583
Dual-excitation confocal laser scanning microscopy was used to image the pH-indicator BCECF, ionophoretically microinjected into stomatal guard cells of V. faba during challenge with peptides derived from hydrophilic domains of the maize auxin-binding protein. Only the peptide corresponding to the C-terminal end (Pz151-163) caused significant changes in cytosolic pH, stimulating rapid alkalinization of 0.4+or-0.1 pH units. Cytosolic pH was clamped using the permeant weak acid, butyrate, and this treatment buffered the peptide-evoked alkalinization. Together with the electrical events monitored at the plasma membrane using whole-cell voltage clamp, it is concluded that [H+] acts as a signal intermediate in the guard cell transduction network. In preliminary experiments using single-wavelength imaging of the Ca indicator Fluo-3, Pz151-163 also stimulated rapid reversible increases in cytosolic Ca.