Divide&Connect: Building up cell-cell continuity during plant cell division – DIVCON

Cell division is an essential process for all living organisms. In plants, unlike in most other eukaryotes, division does not lead to complete abscission. Instead, daughter cells remain permanently connected via Plasmodesmata (PD) pores, which maintain cytosolic, plasma membrane and endoplasmic reticulum cell-cell continuity across their adjacent wall. PD operate as critical routes for communication and molecular exchange between plant cells. They regulate the movement of a wide range of signalling molecules such as transcription factors, small RNAs, hormones, pathogens/disease factors, but also nutrients (hence carbon allocation) between cells, tissues, and organs. As such, PD play a critical role in plant growth and fitness, organ and tissue differentiation and development, and in plant responses to biotic and abiotic stresses. During cytokinesis, hundreds of PD are assembled into the nascent wall, creating a supra-cellular transport network at the plant body level, a situation unique to plants. While PD are indispensable for plant growth and development, to date, we do not know how plant cells assemble PD during cytokinesis, and how they combine the need to divide with the need to connect.

In the DIVCON project, we combine our complementary expertise in PD (Partner 1 -Bayer, LBM, Bordeaux), plant cell division (Partner 2 Caillaud, ENS, Lyon), and membrane dynamics (Partner 3 Taly, IBPC, Paris), to tackle the fundamental question of PD biogenesis during cytokinesis. We aim at understanding how plant cells establish endomembrane/cytosolic cell-cell continuity while dividing, and how this process is integrated with controlled intercellular exchange.
We propose a pioneer research program which integrates molecular and cell biology, molecular dynamic modelling, time super-resolved microscopy and inducible genetic perturbations, with the objectives of:
? Mapping the cellular dynamic events leading to PD biogenesis at unprecedented resolution
? Revealing the key molecular determinants of PD assembly
? Understanding how PD formation and the establishment of cell-cell communication are co-regulated