Plant life depends on cell-to-cell connectivity through the membrane-lined channels called plasmodesmata (PD). These nano-scaled structures play pivotal roles in the orchestration of growth and development and the emerging view is that PD may well represent a consensus target for pathogens and constitute key elements in defence signalling.
PD feature a unique ultrastructural organisation, that we think is central to their function. They are characterised by the close apposition of the endoplasmic reticulum (ER) and the plasma membrane (PM), the two membranes being tethered extremely tight, without undergoing membrane fusion, by unidentified “spoke” elements. These ER-PM membrane contacts are likely to be critical to PD function possibly by favouring ER-PM cross-talk. Likewise, the inherent structural plasticity of PD membrane junction may govern cell-to-cell connectivity. PD are also characterised by high membrane curvature as both the ER and the PM form membrane tubules, with diameters of about 15 nm and 50 nm respectively. Last, PD are compelling examples of membrane functional sub-compartmentalisation with the specialisation of ER and the PM across cell boundary. How lateral membrane heterogeneity is achieved at PD is currently unknown. The unique geometry and specialised membrane arrangement of PD is likely to contribute to their function by locally conferring specific properties to PD membranes. Both proteins and lipids are expected to act together to modulate PD membrane organisation and function.
We aim at understanding the molecular mechanisms underlying PD membrane organisation and remodelling. In particular we are focusing on the role of lipids in defining PD specialised membranes both structurally and functionally.