The seminars take place on the Montpellier Institut Agro/INRA Campus of La Gaillarde (2, place P. Viala Montpellier)

Thursday, December 1st
at 2pm, amphi 206


Marija Smokvarska

(Laboratoire de Biogenèse Membranaire – Villenave-d’Ornon)


A novel mechanism for plasmodesmata mediated cell-cell communication in plants

Intercellular communication is of critical importance for multicellular organisms.  In plants, plasmodesmata are specialized endoplasmic reticulum (ER) – plasma membrane (PM) contact sites (EPCS) that interconnect virtually every single cell within the plant body. They consist on two concentric, tethered, narrow membrane tubules: the outer one being the plasma membrane (PM) and the inner one being a highly constricted endoplasmic reticulum (ER), named the desmotubule; that span through the cell walls of neighboring cells.
Even though they establish a symplastic continuum, molecular flow across plasmodesmata is cautiously regulated in space and time. So far, the local synthesis and degradation of callose, a 1-3 glucan polymer, around plasmodesmata neck has been identified as the master regulator of their transport capacity. Considering plasmodesmata as specialized EPCS, we wondered whether callose was the sole regulator of plasmodesmata transport or if additional elements, such as membrane tethering, could play a role. We focused on Multiple C2 domain Transmembrane region Proteins (MCTPs) which were proposed to act as plasmodesmata ER-PM tethers. Here we identified that MCTP3,4 and 6 are core plasmodesmata proteins, and form homo- and heteromeric complexes. The three members are broadly expressed and critical for proper plant growth and development. They regulate cell-cell trafficking in a callose-independent manner by controlling ER-PM spacing at plasmodesmata, probably through the interaction between C2 domains and the anionic lipid PI4P in the PM. Thus, this work unveils a novel molecular mechanism for regulated intercellular trafficking.

contact : Alexandre Martinière

Contacts IBIP :

Sabine Zimmermann (

Alexandre Martiniere (

Aude Coupel-Ledru (

Chantal Baracco (