title: The origin of phragmoplast asymmetry.
abstract: The phragmoplast coordinates cytokinesis in plants [1]. It directs vesicles to the midzone, the site where they coalesce to form the new cell plate. Failure in phragmoplast function results in aborted or incomplete cytokinesis leading to embryo lethality, morphological defects, or multinucleate cells [2, 3]. The asymmetry of vesicular traffic is regulated by microtubules [1, 4, 5, 6], and the current model suggests that this asymmetry is established and maintained through treadmilling of parallel microtubules. However, we have analyzed the behavior of microtubules in the phragmoplast using live-cell imaging coupled with mathematical modeling and dynamic simulations and report that microtubules initiate randomly in the phragmoplast and that the majority exhibit dynamic instability with higher turnover rates nearer to the midzone. The directional transport of vesicles is possible because the majority of the microtubules polymerize toward the midzone. Here, we propose the first inclusive model where microtubule dynamics and phragmoplast asymmetry are consistent with the localization and activity of proteins known to regulate microtubule assembly and disassembly.
authors.affiliation: School of Biological and Biomedical Sciences, Durham University, Durham DH1 3LE, UK.
authors.forename: Andrei P
authors.initials: AP
authors.lastname: Smertenko
authors.forename: Bernard
authors.initials: B
authors.lastname: Piette
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Hussey
mesh_terms: D002460:Cell Line; D003198:Computer Simulation; D048749:Cytokinesis; D036681:Fluorescence Recovery After Photobleaching; D008164:Luminescent Proteins / Q000378:metabolism; D008856:Microscopy, Fluorescence; D008870:Microtubules / Q000378:metabolism; D008954:Models, Biological; D014026:Nicotiana / Q000166:cytology* / Q000378:metabolism*; D014404:Tubulin / Q000378:metabolism
chemical_list: D008164:Luminescent Proteins; D014404:Tubulin