Plant plasmodesmata bridges form through ER-dependent incomplete cytokinesis

• DOI: 10.1126/science.adn4630
• Publication Date: 2024-10-31T17:59:00Z
• Authors: Ziqiang P. Li; Hortense Moreau; Jules D. Petit; Tatiana S. Moraes; Marija Smokvarska; Jessica Pérez-Sancho; Melina Petrel; Fanny Decoeur; Lysiane Brocard; Clément Chambaud; Magali S. Grison; Andrea Paterlini; Marie Glavier; Lucie Hoornaert; Amit S. Joshi; Etienne Gontier; William A. Prinz; Yvon Jaillais; Antoine Taly; Felix Campelo; Marie-Cécile Cail...; Emmanuelle M. Bayer
• Keywords: [SDV] Life Sciences [q-bio]; 570; Electron Microscope Tomography; Arabidopsis Proteins; [SDV]Life Sciences [q-bio]; Cell Membrane; Plasmodesmata; Arabidopsis; Cell Communication; Endoplasmic Reticulum; Cytokinesis

Diverging from conventional cell division models, plant cells undergo incomplete division to generate plasmodesmata communication bridges between daughter cells. Although fundamental for plant multicellularity, the molecular events leading to bridge stabilization, as opposed to severing, remain unknown. Using electron tomography, we mapped the transition from cell plate fenestrae to plasmodesmata. We show that the endoplasmic reticulum (ER) connects daughter cells across fenestrae, and as the cell plate matures, fenestrae contract, causing the plasma membrane (PM) to mold around constricted ER tubes. The ER’s presence prevents fenestrae fusion, forming plasmodesmata, whereas its absence results in closure. The ER-PM protein tethers MCTP3, MCTP4, and MCTP6 further stabilize nascent plasmodesmata during fenestrae contraction. Genetic deletion in Arabidopsis reduces plasmodesmata formation. Our findings reveal how plants undergo incomplete division to promote intercellular communication.