Plasmodesmata - membrane tunnels with attitude

► Recent technologies have increased our knowledge of the structural components of plasmodesmata (PD). ► Plasma membrane and endoplasmic reticulum are core components of PD and add further pathways for cell-to-cell trafficking. ► Identification of diverse classes of membrane proteins at PD point to PD as platforms for integrating signals for growth. ► Signals, including reactive oxygen species, control callose deposition in the wall, PD structure and molecular flux.