Effects of sulphite on properties of tonoplast vesicles from the CAM plant Kalanchoë daigremontiana

Summary The paper reports on studies dealing with the effects of sulphite on the fluidity of the tonoplast in the CAM plant Kalanchoe daigremontiana . Temperature profiles of membrane fluidity were monitored by measurements of fluorescence polarisation in fluorescence labelled tonoplastic vesicles. It was found that sulphite applied to leaf tissue prior to membrane isolation significandy decreased the fluidity of the tonoplast. Addition of sulphite to the assay medium had no effect showing that the changes of tonoplast fluidity by sulphite are not an in vitro effect. The adaptive changes in the tonoplast fluidity were accompanied by stimulation of ATPase activity and changes in the relative amounts of proteins in the ATPase subunits A, B, and C.