Organized microtubule arrays are essential for cell division, cell migration, trafficking, and cell
morphogenesis. Proliferating and migrating animal cells feature radial arrays of centrosome-anchored
microtubules, whereas differentiated animal cells and all plant cells can organize their microtubules
without centrosomes. These noncentrosomal microtubule arrays are involved in vital cellular functions,
however the mechanisms involved in microtubule organization in the absence of centrosomes are not
Consistent with the essential functions of organized microtubule arrays, plant and animal cells
widely utilize evolutionarily conserved molecules to regulate microtubule organization. A ring-like
microtubule array is organized at the cortex of plant cells entering mitosis. This microtubule array, the
preprophase band (PPB), is important for spindle guidance and positioning of the cell division plane. A
complex of evolutionarily conserved proteins that include TON1 and TRM proteins, which are
homologous to the human microtubule-anchoring centrosomal proteins FOP and CAP350, and the
protein phosphatase PP2A drives the organization of the PPB. The function of TON1 proteins in the
complex of TON1/TRM/Ton2/PP2a proteins promoting PPB array formation will be tested.
Understanding the mechanism of PPB microtubule array organization will uncover common
mechanisms and specific modifications driving the formation of centrosomal and noncentrosomal arrays.