Photosynthesis-Dependent Volume Regulation in Guard Cell Protoplasts from <italic>Vicia faba</italic> L.

Abstract

A rapid and convenient procedure was developed for isolating guard cell protoplasts (GCPs) from epidermal strips of Vicia faba L. The mean rates of O2 uptake in the dark and evolution in light of the isolated GCPs were 200 and 290 μmol O2 mg−1 Chl h−1, respectively, showing net O2 evolution in light. Photosynthetic O2 evolution was suppressed completely by 5 μm DCMU. Addition of 5 μm DCMU to the incubation medium after 30 min of light exposure also suppressed the light-induced swelling of GCP, indicating possible participation of PS II in volume regulation in GCP.