Biophysical Society Thematic Meeting| Aussois 2019

Biology and Physics Confront Cell-Cell Adhesion

Wednesday Speaker Abstracts

MECHANICS AND DYNAMICS OF CELL-CELL ADHESION IN PLANTS Stéphane Verger 1 ; Elsa Demes 1 ; Yuchen Long 2 ; Arezki Boudaoud 2 ; Grégory Mouille 3 ; Olivier Hamant 2 ; 1 Swedish University of Agricultural Sciences, Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Umeå, Sweden 2 Université de Lyon, ENS de Lyon, UCBL, INRA, CNRS, Laboratoire de Reproduction et Développement des Plantes, Lyon 7eme, France 3 INRA, AgroParisTech, CNRS, Université Paris-Saclay, Institut Jean-Pierre Bourgin, Versailles, France How cell-cell adhesion is achieved is a fundamental question in the development of multicellular organisms. Surprisingly, this question remains largely under-explored in plants and much remains to be discovered. In plants, cell-cell adhesion is physically mediated by the cell wall. This is not only passive: in previous work we identified a complex signaling pathway for the active maintenance of cell-cell adhesion in plants (Verger et al. 2016). Furthermore, we demonstrated how tensile stress in tissues tends to pull the cells apart in the epidermis during growth and development and may also act as an instructive cue for cell adhesion maintenance in plants (Verger et al. 2018). In turn, loss of cell adhesion impairs proper development. For instance, we showed how torsion relies on adhesion and anisotrotpic growth in stems (Verger et al. 2019). Here, we identified a set of mutants, from the model species Arabidopsis thaliana, displaying characteristic cell-cell adhesion defects. These include mutants in actin filament nucleation (ARP2/3 and SCAR/WAVE complexes), epidermal identity transcription factors (ATML1 and PDF2) and a mechanosensitive calcium channel (DEFECTIVE KERNEL1). While we are investigating the actual cause for the loss of cell adhesion in these mutants, our current hypothesis is that mechanical stress in the epidermis triggers a reorganization of the actin network in order to polarize polysaccharides depositions towards cell- cell connections which are the most under mechanical stress’ threat to reinforce and maintain adhesion. Maintenance of cell adhesion would further promote the supracellular propagation of mechanical stress in a “tension-adhesion” feedback loop, suggesting a convergent principle for the maintenance of cell adhesion between plants and animals, but based on divergent adhesion mechanisms (e.g. cell wall in plants). References: Verger, S., et al., 2016. Development Verger, S., et al., 2018. eLife Verger, S., et al., 2019. Front. Plant Sci.

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