Fig 5. Time course of FM4-64 uptake in a growing Picea wilsonii pollen tube.

(A–E) FM4-64 uptake into the pollen tube followed a strict time sequence, and dye uptake occurred mainly along the apex in a normally growing pollen tube of Picea wilsonii. (F–H) FM4-64 staining of a 0.2% DMSO-treated pollen tube. FM4-64 internalization occurred in the apical region of a growing pollen tube. (K–O) FM4-64 staining of a 0.5 μM TSA-treated pollen tube, showing nonuniform internalization from both sides of the tube. (P–T) FM4-64 staining of a pollen tube cultured in 0.5 mM NaB-containing medium for 24 h. The fluorescence was distributed unevenly and showed no distinct direction during the course of uptake. Bar = 20 μm (arrows indicate the direction of dye distribution).