A Rab/Kinesin-12/kinase module couples vesicle delivery and phragmoplast dynamics during plant cell cytokinesis

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 cell division plane by the phragmoplast, a cytoskeletal structure that undergoes continuous remodeling. Endomembrane trafficking and phragmoplast remodeling are tightly coupled, indicating the existence of active crosstalk. However, although many molecular regulators of membrane trafficking and cytoskeletal organization are known, it remains poorly understood how these processes are coordinated. Here, we describe a regulatory module consisting of the membrane-associated GTPase RAB-A2a, cytoskeleton-associated Class II Kinesin-12 proteins, and the Fused kinase ortholog TIO. We provide evidence that the interaction between these molecules at the midzone, and differential functions of Class II Kinesin-12 members at the leading and lagging cell plate domains, are essential for cytokinesis initiation and progression in Arabidopsis by simultaneously targeting vesicles to the midzone and coupling phragmoplast remodeling to vesicle delivery.