Opening of the mPTP caused by Lat-B treatment, as visualized by reduced calcein fluorescence in mitochondria. Root hair cells were loaded with calcein, and the green fluorescence represented mitochondria labeled with calcein in the root hairs. The data were representative of six independent experiments. (A) Fluorescence photograph of calcein trapped in the mitochondria in a control root hair. (B) Fluorescence image of calcein in the mitochondria after 5 min of treatment with 500 nM Lat-B in the same control root hair. (C) Changes in the fluorescence of trapped calcein over time. The diamond curve showed the decrease in calcein fluorescence induced by 500 nM Lat-B treatment in 10 min duration; the dotted curve showed the change with a 30-min pretreatment with 2 μM Cs A before Lat-B application; and the square curve represented the buffer control in drug-free medium. F0 represented the fluorescence intensity value of calcein before treatments, and F represented the fluorescence intensity value in same mitochondria after treatments. Scale bars = 10 μm.