A Rab-Kinesin12-Fused kinase module couples vesicle delivery and phragmoplast remodelling during cytokinesis in Arabidopsis

Cytokinesis is a key process in the development of multicellular organisms, through both formative and proliferative divisions. In land plants, successful cytokinesis requires precise targeting of Golgi-derived vesicles to the future division plane by the phragmoplast, a cytoskeletal structure that undergoes continuous remodelling. Endomembrane trafficking and phragmoplast remodelling are tightly coupled, indicating the existence of active crosstalk. However, although many molecular regulators of membrane trafficking and cytoskeletal organisation are known, it remains poorly understood how these processes are co-ordinated. Here, we describe a regulatory module consisting of the membrane-associated GTPase RAB-A2a, cytoskeleton-associated Class II Kinesin-12s, and the Fused kinase orthologue TIO. We provide evidence that the interaction between these molecules at the midzone is essential for cytokinesis in Arabidopsis through simultaneously targeting vesicles to the midzone and coupling phragmoplast remodelling to vesicle delivery.