MICROELECTROPHORETIC AND 9-AMINOACRIDINE FLUORESCENCE STUDY OF THE SURFACE ELECTRICAL-PROPERTIES OF SUSPENSION-CULTURED CATHARANTHUS-ROSEUSCELLS AND ISOLATED PROTOPLASTS - EFFECTS OF ABSCISIC-ACID TREATMENT

The effects of abscisic acid (ABA) treatments on the surface electrica l properties of cells and isolated protoplasts from Catharanthus roseu s cell suspension cultures were studied by electrophoretic mobility an d 9-aminoacridine (9AA) fluorescence measurements. The surface charge densities of the cells and protoplasts estimated from electrokinetic d ata were -0.064 C m(-2) and -0.048 C m(-2) respectively. These values were close to that estimated by 9AA fluorescence technique i.e., -0.05 3 C m(-2) for the cells and -0.041 C m(-2) for the isolated protoplast s accordingly. The net negative surface charge density decreased after application of 10 mu M and 50 mu M ABA in both cells and protoplats, the more pronounced effect being observed at 10 mu M ABA. When 100 mu M ABA was supplemented to the cell suspension culture the opposite eff ect was observed. The average charge density increased to -0.074 C m(- 2) for the cells, and to -0.055 C m(-2) for protoplasts, as revealed f rom the 9AA measurements. The results are discussed in terms of specif ic concentration dependent ABA-induced alterations of the electrostati c properties of cell and protoplast membranes.