Preparation of rolled epidermis of vicia faba l. So that stomata are the only viable cells: Analysis of guard cell potassium by flame photometry

Abstract

A rolling technique is described with which cells in epidermal strips of V. faba were differentially broken so that only guard cells remained alive and functional. In rolled epidermis potassium was retained only in live guard cells, as judged by staining with cobaltinitrite. Potassium in rolled and rinsed epidermal strips, analysed by flame photometry, showed a fivefold increase on the average when stomata opened in leaves under light. Guard cell solute potential, estimated plasmolytically, decreased 12 bars for an increase of 10 μm in stomatal aperture. The corresponding increase in guard cell potassium was sufficient to account for a solute potential change of as much as 11 bars. Thus, the results are in general agreement with previous studies with radioactive label or electron microprobes indicating that potassium is the major osmotic solute involved in stomatal movement of Vicia. © 1973 CSIRO.