Fig. 5.

The ROP1-exocytosis signaling is required for sensitive response to guidance signal. a The redistribution of active ROP1 in response to guidance signal gradients is slower in sec8-4 and ren1-3 than in wild-type (WT). Dashed lines: active ROP1 distribution in the absence of signal gradients; solid lines: active ROP1 distribution after being exposed to signal gradients for a certain period of time. b Simulated trajectories of sec8-4 and ren1-3 pollen tubes exposed to 1× or 0.5× signal gradient. Lines of wild-type and sec8-4 at 1× signal gradient are overlapping. The tip of pollen tube is at [0, 0] when being exposed to guidance signal. Black lines represent the midline of the pollen tube before being exposed to guidance signal. Circles represent the source of the guidance signal. c, d Average trajectories of wild-type, ren1-3 and sec8-4 pollen tubes growing toward gelatin beads containing 0.05 μM c or 0.02 μM AtLURE1 d in the semi-in vitro guidance assay. Dashed lines in show the outline of the gelatin beads. Error bars show s.e.m. x and y: the horizontal and vertical directions of the plane in which pollen tubes are growing