Functional characterization of a new plant DYNAMIN protein controlling cell shape, through actin cytoskeleton dynamics

International audience; A forward genetic strategy, combining tomato EMS mutant variability and mapping-by-sequencing (Garcia et al., 2016; Musseau et al., 2017) allowed the identification of a DYNAMIN protein, as a key regulator of tomato fruit tissue morphology. DYNAMINs (DYNs) are large GTPase that can interact with cytoskeleton-associating proteins. In animals, DYNs are reported to be involved in cytokinesis, membrane trafficking, cytoskeletal dynamics and pathogen resistance (Konopka et al., 2006; Praefcke & Mcmahon, 2004). Plants present homologs for most dynamins found in animals, with some proven to be functional redundant. However, the role and molecular mechanisms of this particular dynamin have never been described in plants so far.In order to investigate its role in plants, experiments were conducted in both tomato and Arabidopsis thaliana models. dyn mutants share common aberrant cell size and shape, affecting pericarp cells in tomato and trichomes in Arabidopsis. Aberrant Arabidopsis trichome morphology is strikingly similar to the well described Arabidopsis mutants affected in the WAVE and ARP2/3 pathways, that are involved in actin filament nucleation (Isner et al., 2017; Sambade et al., 2014; Zimmermann et al., 2004). Our data suggest a role of this plant dynamin in actin cytoskeleton remodeling, supporting rapid cell elongation.