| Abstract: | Guard cell and epidermal/subsidiary cell protoplasts obtainedby enzymic digestion of peeled Commelina communis leaf epidermiswere separated and purified by discontinuous density gradientccntrifugation with media based on Percoll (Pharmacia Fine ChemicalsAB, Uppsala, Sweden). The cell types were recovered over 99.9%pure at yields exceeding 50% efficiency, and mesophyll contaminationcould be virtually eliminated when desired. Osmotic characteristicsof the protoplast types were evaluated and compared to in vivovalues, and the viability of the protoplasts, assessed usinga range of criteria, was found to be high. Purified Commelinaguard cell protoplasts were able to evolve O2 when illuminated,and this was substantially reduced in the presence of the inhibitorDCMU, indicating that they possess photosystem II activity.Specific advantages of this method of protoplast purification,and the potential uses of separate suspensions of guard cellsand epidermal/subsidiary cells in experiments on stomatal physiologyare discussed. Key words: Commelina communis, Protoplasts, Epidermis |
