The Wasteneys lab is discovering the mechanisms behind the shape of plants. In particular, we explore the mechanisms by which cortical arrays of cytoskeletal elements known as microtubules influence the mechanical properties of cellulosic cell walls. By employing forward and reverse genetic strategies with the powerful model system Arabidopsis, we have discovered several microtubule-associated proteins that are critical for the spatial organization and function of cortical microtubule arrays. Mutant alleles of these proteins cause defects in cell morphology as a consequence of altered wall characteristics. We are now exploiting these mutants as model systems to identify the functional connection between microtubule activity and the physical properties of the wall components responsible for directional cell expansion.