title: Actin filament dynamics are dominated by rapid growth and severing activity in the Arabidopsis cortical array.
abstract: Metazoan cells harness the power of actin dynamics to create cytoskeletal arrays that stimulate protrusions and drive intracellular organelle movements. In plant cells, the actin cytoskeleton is understood to participate in cell elongation; however, a detailed description and molecular mechanism(s) underpinning filament nucleation, growth, and turnover are lacking. Here, we use variable-angle epifluorescence microscopy (VAEM) to examine the organization and dynamics of the cortical cytoskeleton in growing and nongrowing epidermal cells. One population of filaments in the cortical array, which most likely represent single actin filaments, is randomly oriented and highly dynamic. These filaments grow at rates of 1.7 microm/s, but are generally short-lived. Instead of depolymerization at their ends, actin filaments are disassembled by severing activity. Remodeling of the cortical actin array also features filament buckling and straightening events. These observations indicate a mechanism inconsistent with treadmilling. Instead, cortical actin filament dynamics resemble the stochastic dynamics of an in vitro biomimetic system for actin assembly.
authors.affiliation: Department of Biological Sciences, Hansen Life Sciences Research Building, Purdue University, West Lafayette, IN 47907, USA.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Staiger
authors.forename: Michael B
authors.initials: MB
authors.lastname: Sheahan
authors.forename: Parul
authors.initials: P
authors.lastname: Khurana
authors.forename: Xia
authors.initials: X
authors.lastname: Wang
authors.forename: David W
authors.initials: DW
authors.lastname: McCurdy
authors.forename: Laurent
authors.initials: L
authors.lastname: Blanchoin
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism* / Q000648:ultrastructure*; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D032701:Biomimetics; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000494:pharmacology; D003599:Cytoskeleton / Q000378:metabolism; D053778:Thiazolidines / Q000494:pharmacology
chemical_list: D019086:Bridged Bicyclo Compounds, Heterocyclic; D053778:Thiazolidines; C037068:latrunculin B