EFFECTS OF SULFITE ON PROPERTIES OF TONOPLAST VESICLES FROM THE CAM PLANT KALANCHOE-DAIGREMONTIANA

The paper reports on studies dealing with tile effects of sulphite on the fluidity of the tonoplast in the CAM plant Kalanchoe daigremontian a. Temperature profiles of membrane fluidity were monitored by measure ments of fluorescence polarisation in fluorescence labelled tonoplasti c vesicles. It was found that sulphite applied to leaf tissue prior to membrane isolation significantly decreased the fluidity of the tonopl ast. Addition of sulphite to the assay medium had no effect showing th at the changes of tonoplast fluidity by sulphite are not an in vitro e ffect. 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.