title: Microtubule dynamics of the centrosome-like polar organizers from the basal land plant Marchantia polymorpha.
abstract: The liverwort Marchantia employs both modern and ancestral devices during cell division: it forms preprophase bands and in addition it shows centrosome-like polar organizers. We investigated whether polar organizers and preprophase bands cooperate to set up the division plane. To this end, two novel green fluorescent protein-based microtubule markers for dividing cells of Marchantia were developed. Cells of the apical notch formed polar organizers first and subsequently assembled preprophase bands. Polar organizers were formed de novo from multiple mobile microtubule foci localizing to the nuclear envelope. The foci then became concentrated by bipolar aggregation. We determined the comet production rate of polar organizers and show that microtubule plus ends of astral microtubules polymerize faster than those found on cortical microtubules. Importantly, it was observed that conditions increasing polar organizer numbers interfere with preprophase band formation. The data show that polar organizers have much in common with centrosomes, but that they also have specialized features. The results suggest that polar organizers contribute to preprophase band formation and in this way are involved in controlling the division plane. Our analyses of the basal land plant Marchantia shed new light on the evolution of plant cell division.
authors.affiliation: Botany Department, School of Biology and Chemistry, Osnabrück University, Barbarastraße 11, 49076, Osnabrück, Germany.
authors.forename: Henrik
authors.initials: H
authors.lastname: Buschmann
authors.affiliation: Botany Department, School of Biology and Chemistry, Osnabrück University, Barbarastraße 11, 49076, Osnabrück, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Holtmannspötter
authors.affiliation: Botany Department, School of Biology and Chemistry, Osnabrück University, Barbarastraße 11, 49076, Osnabrück, Germany.
authors.forename: Agnes
authors.initials: A
authors.lastname: Borchers
authors.affiliation: Botany Department, School of Biology and Chemistry, Osnabrück University, Barbarastraße 11, 49076, Osnabrück, Germany.
authors.forename: Martin-Timothy
authors.initials: MT
authors.lastname: O'Donoghue
authors.affiliation: Botany Department, School of Biology and Chemistry, Osnabrück University, Barbarastraße 11, 49076, Osnabrück, Germany.
authors.forename: Sabine
authors.initials: S
authors.lastname: Zachgo
mesh_terms: D015415:Biomarkers / Q000378:metabolism; D002455:Cell Division; D018385:Centrosome / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D049452:Green Fluorescent Proteins / Q000378:metabolism; D047008:Marchantia / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D008870:Microtubules / Q000378:metabolism*; D009928:Organ Specificity; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D011418:Prophase; D014404:Tubulin / Q000235:genetics / Q000378:metabolism
chemical_list: D015415:Biomarkers; D010940:Plant Proteins; D014404:Tubulin; D049452:Green Fluorescent Proteins
keywords: Marchantia; centrosome; division plane alignment; land plant; microtubule; mitosis; polar organizer; preprophase band