In the absence of cell migration, the orientation of cell divisions is crucial for body plan determination in plants. The position of the division plane in plant cells is set up premitotically via a transient cytoskeletal array, the preprophase band, which precisely delineates the cortical plane of division. Here we describe a protein complex that targets protein phosphatase 2A activity to microtubules, regulating the transition from the interphase to the premitotic microtubule array. This complex, which comprises TONNEAU1 and a PP2A heterotrimeric holoenzyme with FASS as regulatory subunit, is recruited to the cytoskeleton via the TONNEAU1-recruiting motif family of proteins. Despite the acentrosomal nature of plant cells, all members of this complex share similarity with animal centrosomal proteins involved in ciliary and centriolar/centrosomal functions, revealing an evolutionary link between the cortical cytoskeleton of plant cells and microtubule organizers in other eukaryotes.

Controlling cell division plane orientation is essential for morphogenesis in multicellular organisms. In plant cells, the future cortical division plane is marked before mitotic entry by the preprophase band (PPB). Here, we characterized an (TON1 Recruiting Motif) mutant that impairs PPB formation but does not affect interphase microtubules. Unexpectedly, PPB disruption neither abolished the capacity of root cells to define a cortical division zone nor induced aberrant cell division patterns but rather caused a loss of precision in cell division orientation. Our results advocate for a reassessment of PPB function and division plane determination in plants and show that a main output of this microtubule array is to limit spindle rotations in order to increase the robustness of cell division.