Effects of mitochondria-selective fluorescent probes on mitochondrial movement in Arabidopsis mesophyll cells evaluated by using the quantification

Mitochondria-selective fluorescent probes such as MitoTracker are often used for mitochondria imaging in various plants. Although some of the probes are reported to induce mitochondria dysfunction in animal cells, the effect on plant cells remains to be determined. In the present study, we applied quantitative methods to analyze mitochondrial movement, speed frequency, and speed-angle changes, based on trajectory analysis of mitochondria in mesophyll protoplast cells of Arabidopsis thaliana expressing the mitochondria-localized fluorescent protein. Using the quantitative method, we assessed whether MitoTracker Red (FM and CMXRos) induce mitochondria dysfunction in A. thaliana. Although both the fluorescent probes well-stained mitochondria, the CMXRos probe, not the FM probe, gave a severe effect on mitochondrial movement at the low concentration (10 nM), indicating a MitoTracker-induced mitochondria dysfunction in A. thaliana. These results revealed that our quantitative method based on mitochondrial movement can be used to determine the appropriate concentrations of mitochondria-selective fluorescent probes in plants.