Ultra‐small TiO 2 nanoparticles disrupt microtubular networks in Arabidopsis thaliana

In spite of the mounting concerns, current understanding of the extent and mechanisms of phytotoxicity of manufactured nanomaterials remains limited. Here we show that in Arabidopsis thaliana , ultra‐small anatase TiO 2 nanoparticles cause reorganization and elimination of microtubules followed by the accelerated and 26S proteasome‐dependent degradation of tubulin monomers. Similar to other microtubule‐disrupting agents, TiO 2 nanoparticles induce isotropic growth of root cells. Because microtubules are essential for the normal function of all eukaryotic cells, these results reveal a potentially important consequence of environmental pollution by this widely used nanomaterial.