Figure 9.

Distribution of the Cytosol and Organelle Markers after Filipin Treatment.

(A) Cytosolic GFP expression marks the entire volume of the cytosol in growing root hairs with the exception of membranous compartments and organelles in control conditions. Filipin-positive apical compartments formed after a 25-min treatment with 10 μg·mL⁻¹ filipin are GFP negative and are separated from the cytosol.

(B) The ER-GFP construct labels dynamic ER profiles distributed throughout the root hair, with the exception of the apical dome in control conditions. A 25-min treatment with 10 μg·mL⁻¹ filipin leads to the formation of apical compartments that are negative for the ER marker.

(C) The mitochondrial GFP construct labels mitochondria actively moving in the whole root hair but only rarely in the extreme apex in control conditions. A 25-min treatment with 10 μg·mL⁻¹ filipin results in the movement of mitochondria into the apex but not into filipin-positive apical compartments.

(D) GFP expression in plastids shows these large organelles far from the extreme apex in control conditions. A 25-min treatment with 10 μg·mL⁻¹ filipin revealed that plastids do not participate in the formation of filipin-positive apical compartments. DIC image (top row in each panel), single confocal planes (rows 2 and 3 in each panel), and confocal-DIC or filipin-GFP merged images (last row in each panel).

Bar = 5 μm.