Pontentiometric Cyanine DyesAreSensitive Probes for Mitochondria inIntact Plant Cells' KINETINENHANCESMITOCHONDRIALFLUORESCENCE

Selected fluorescent dyesweretested foruptake bymitochrondria in intact cells ofbarley, maize, andonion. Thecationic cyanine dye3,3'diheptyloxacarbocyanine iodide [DiOC7(3)j accumulated inmitochondria within 15to30minutes without appreciable staining ofother protoplasmic constituents. Thenumber, shape, andmovement ofthefluorescentmitochondria could beseenreadily, andthefluorescence intensity ofthemitochondria could bemonitored with amicroscope photometer. Fluorescence waseliminated in1to5minutes bytheprotonophore carbonyl cyanide m-chlorophenylhydrazone (CCCP) indicating that maintenance ofdyeconcentration wasdependent ontheinside-negative transmembrane potential maintained byfunctional mitochondria. Fluorescence ofprestained mitochondria wasenhc within 5to10minutes after addition of0.1minlimolar kinetin tocells. Thefluorescence inkinetintreated cells wasdissipated byCCCP.These results suggest that kinetin interacted with respiratory processes resulting inhigher potential across themitochondrial membrane.