| Abstract: | We describe here, for the first time, the effects of the hydrophobiccationic dye 10-n-nonyl acridinium-orange-chloride (NAO) onprotoplast development, photosynthetic capacity and infrastructure.NAO is specifically taken up by plant mitochondria under vitalstaining conditions (0.62 µM; 15–30 min). No otherorganelles revealed the bright green fluorescence typical forthis dye. Cell division and growth of protoplast cultures fromBrassica napus are severely reduced after vital staining withNAO. At higher NAO concentrations (1.25–2.5 µM;30 min) protoplast regeneration is fully blocked. Electron microscopyreveals that such a treatment causes the mitochondria to swellto a size several-fold larger than in control protoplasts. Otherorganelles appeared to be unaffected by NAO. Measurement ofoxygen production and consumption of protoplasts indicated thatNAO (1.25 µM; 30 min) was without effect on respirationin the dark, but subsequently caused a 50% reduction in oxygenevolution in the light. These results suggest that NAO is actingboth as an uncoupler as well as an ionophore. We discuss thevalue of NAO as a potentially important tool in somatic hybridizationexperiments by influencing the outcome of mitochondrial segregation/recombination. Key words: Brassica napus, mitochondria, NAO, protoplast regeneration |
