title: Dynamic actin controls polarity induction de novo in protoplasts.
abstract: Cell polarity and axes are central for plant morphogenesis. To study how polarity and axes are induced de novo, we investigated protoplasts of tobacco Nicotiana tabacum cv. BY-2 expressing fluorescently-tagged cytoskeletal markers. We standardized the system to such a degree that we were able to generate quantitative data on the temporal patterns of regeneration stages. The synthesis of a new cell wall marks the transition to the first stage of regeneration, and proceeds after a long preparatory phase within a few minutes. During this preparatory phase, the nucleus migrates actively, and cytoplasmic strands remodel vigorously. We probed this system for the effect of anti-cytoskeletal compounds, inducible bundling of actin, RGD-peptides, and temperature. Suppression of actin dynamics at an early stage leads to aberrant tripolar cells, whereas suppression of microtubule dynamics produces aberrant sausage-like cells with asymmetric cell walls. We integrated these data into a model, where the microtubular cytoskeleton conveys positional information between the nucleus and the membrane controlling the release or activation of components required for cell wall synthesis. Cell wall formation is followed by the induction of a new cell pole requiring dynamic actin filaments, and the new cell axis is manifested as elongation growth perpendicular to the orientation of the aligned cortical microtubules.
authors.affiliation: Botanical Institute, Molecular Cell Biology, Karlsruhe Institute of Technology, Kaiserstr. 2, D-76128 Karlsruhe, Germany. beatrix.zaban@kit.edu
authors.forename: Beatrix
authors.initials: B
authors.lastname: Zaban
authors.forename: Jan
authors.initials: J
authors.lastname: Maisch
authors.forename: Peter
authors.initials: P
authors.lastname: Nick
mesh_terms: D000199:Actins / Q000378:metabolism*; D000595:Amino Acid Sequence; D029681:Arabidopsis Proteins / Q000378:metabolism; D019521:Body Patterning / Q000187:drug effects; D016764:Cell Polarity / Q000187:drug effects; D003599:Cytoskeleton / Q000187:drug effects / Q000378:metabolism; D008954:Models, Biological; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000494:pharmacology; D011523:Protoplasts / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D012038:Regeneration / Q000187:drug effects; D013696:Temperature; D013997:Time Factors; D059008:Time-Lapse Imaging; D014026:Nicotiana / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism
chemical_list: D000199:Actins; D029681:Arabidopsis Proteins; D009842:Oligopeptides; C047981:arginyl-glycyl-aspartic acid