Fig. 1
From: Exocytosis-coordinated mechanisms for tip growth underlie pollen tube growth guidance
A model of exocytosis-controlled pollen tube tip growth. a A conceptual model of pollen tube tip growth. Exocytosis-mediated positive and negative feedback loops generate the apical cap of active ROP1 (red crescent) in the PM. ROP1-dependent exocytosis (blue circles) also delivers soft pectin (light green) to the pollen tube apex, which is converted to hard pectin (dark green) on the shank. The resulted asymmetric cell wall extensibility together with turgor pressure (“P” and black arrows) determines the strain rates and thereby the geometry of the cell wall. b–e Loss of the ROP1 deactivator, REN1, results in broader active ROP1, broader soft pectin distribution, and wider cell. b Simulated and confocal microscopy images of wild-type and ren1-1 Arabidopsis pollen tubes expressing CRIB4-GFP that shows the distribution of active ROP1. Only the tip region of pollen tubes was shown. c Simulated and observed distribution of active ROP1 in wild-type and ren1-1 pollen tubes. The observed distribution is the average distribution measured from 24 wild-type or 14 ren1-1 pollen tubes. d Confocal microscopy images of pectin immunostaining of wild-type and ren1-1 pollen tubes with JIM7 and JIM5. e Observed and simulated distribution of pectins in wild-type and ren1-1 pollen tubes. Error bars show s.e.m. Scale bar: 5 μm
