Actin filament dynamics are dominated by rapid growth and severing activity in the Arabidopsis cortical array.
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.
Staiger
Christopher J
CJ
Department of Biological Sciences, Hansen Life Sciences Research Building, Purdue University, West Lafayette, IN 47907, USA.
Sheahan
Michael B
MB
Khurana
Parul
P
Wang
Xia
X
McCurdy
David W
DW
Blanchoin
Laurent
L
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
D019086:Bridged Bicyclo Compounds, Heterocyclic; D053778:Thiazolidines; C037068:latrunculin B