Rhodamine 123, as a vital stain for mitochondria of plant cells

Rhodamine 123 (Rh 123), a relatively new mitochondrial marker, little used in the study of plant cells, was tested on excized leaves of Elodea canadensis Michx. and on suspension-cultured cells of Ranunculus serbicus Vis. In both preparations, the dye accumulated rapidly and selectively in the mitochondria whose number, morphology and cell distribution could be easily observed. In the presence of Rh 123, cytoplasmic movements could also be perceived and the spatial arrangement of the mitochondria with respect to that of the auto-fluorescent chloroplasts was studied in connection with a normal or altered cytoskeletal framework. The specific uptake of Rh 123 by the organdies seemed to be potential-dependent since it was influenced by cations, ionophores and inhibitors of electron transport. Short exposures to the stain were practically non-toxic, whereas prolonged treatments (6–20 h) provoked specific alterations in structure of the mitochondria. The data reported here indicate that Rh 123 may be an excellent vital stain to study the morphology, function and dynamics of the mitochondria in living plant cells.