Fig. 2

Exocytosis plays a central role in regulating both ROP1 signaling and cell wall mechanics. a The distribution of active ROP1 changes with the level of exocytosis. The broadness of active ROP1 distribution is represented by the full width at half maximum (FWHM) of the distribution curves (measured from 24 wild-type and 21 sec8-4 pollen tubes). The FWHM of active ROP1 increases when exocytosis rate is moderately reduced (by <56%), but drops to 0 (i.e., loss of ROP1 polarity) when exocytosis is severely reduced (by >56%). Circles and squares are results of simulation and measurement, respectively. Error bars show s.e.m. ***P ≤ 0.001 (Student’s t test). b Simulation and confocal microscopy images of wild-type and sec8-4 pollen tubes expressing CRIB4-GFP. Only the tip region of pollen tubes was shown. c Confocal microscopy images of pectin immunostaining of wild-type and sec8-4 pollen tubes with JIM7 and JIM5. d Observed and simulated distribution of pectins in wild-type and sec8-4 pollen tubes. Error bars show s.e.m. Scale bar: 5 μm