Fast motion and rapid actuation in plants

Some plants generate fast movements when mechanically stimulated, and use this ability to disperse their seeds, protect themselves against predators or get extra-nutrients (Dumais & Forterre 2012, Poppinga et al 2013). Among these nastic movements, the carnivorous plant Venus flytrap (Dionaea muscipula), whose leaves snaps together in a fraction of second to catch insect, has long been a paradigm for study (Darwin 1875, Escalante-Perez et al. 2011). Whereas the role of elastic instability in the trapping mechanism seems to be supported at the macroscopic level (Forterre et al 2005, Poppinga & Joyeux 2011), the mechanism by which the plant actively bends to overcome the instability-threshold remains unknown and is still a matter of debate (Hill & Findlay 1981, Williams & Bennett 1982, Volkov et al 2008). In this project, we try to unveil the physical mechanisms responsible for active movements in plants by carrying micro-mechanical measurements at the tissue and cellular level. We use the Venus flytrap as a model plant to address the main hypotheses found in the literature for such movements (e.g. rapid change of turgor pressure, rapid cell wall actuation). Experiments combine cellular pressure probe and micro/nano-indentation techniques.