(A) Eduard Strasburger’s drawings (from 1884) of a plant cell at different stages of division show a cell plate forming. Drawings are courtesy of Dieter Volkmann, and the complete figure can be seen in Volkmann et al., 2012. (B) After arrival at the trans-Golgi network (TGN), newly synthesized proteins from the Golgi or previously endocytosed cargo proteins are sorted or recycled back to the plasma membrane, respectively, or trafficked to the vacuole (via late endosomal trafficking). Richter et al. have shown that, in non-dividing cells, four proteins (BIG1-4) belonging to the ARF-GEF family control secretory trafficking and transport to the vacuole. Another ARF-GEF, GNOM, regulates endocytic recycling of proteins, such as PIN1. In dividing cells, a plant-specific transient membrane compartment, the cell plate, is formed via BIG1-4-mediated trafficking of vesicles along the secretory pathway, but also via BIG1-4-mediated re-routing of endocytic recycling cargo to the cell-division plane. Interestingly, GNOM-dependent polar relocalisation of PIN1 is maintained despite BIG1-4 re-routing the endocytic recycling cargo.
Illustrations by Eduard Strasburger.