Live Cell Imaging Reveals Structural Associations between the Actin and Microtubule Cytoskeleton in Arabidopsis

Arun Sampathkumar,Staffan Persson,Ryan Gutierrez,Seth Debolt,Tijs Ketelaar,Jelmer J Lindeboom,David W Ehrhardt

doi:10.1105/tpc.111.087940

Arun Sampathkumar, Staffan Persson + Show 5 more

Open Access

https://doi.org/10.1105/tpc.111.087940

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Abstract

In eukaryotic cells, the actin and microtubule (MT) cytoskeletal networks are dynamic structures that organize intracellular processes and facilitate their rapid reorganization. In plant cells, actin filaments (AFs) and MTs are essential for cell growth and morphogenesis. However, dynamic interactions between these two essential components in live cells have not been explored. Here, we use spinning-disc confocal microscopy to dissect interaction and cooperation between cortical AFs and MTs in Arabidopsis thaliana, utilizing fluorescent reporter constructs for both components. Quantitative analyses revealed altered AF dynamics associated with the positions and orientations of cortical MTs. Reorganization and reassembly of the AF array was dependent on the MTs following drug-induced depolymerization, whereby short AFs initially appeared colocalized with MTs, and displayed motility along MTs. We also observed that light-induced reorganization of MTs occurred in concert with changes in AF behavior. Our results indicate dynamic interaction between the cortical actin and MT cytoskeletons in interphase plant cells.

Highlights

The cytoskeleton supports many fundamental cellular processes, including morphogenesis, cell division, and vesicle trafficking (Goode et al, 2000; Fu et al, 2005; Collings, 2008; Gutierrez et al, 2009; Petrasek and Schwarzerova, 2009; Szymanski, 2009)
Because jasplakinolide has not been extensively employed in plant cell biology, we first grew Arabidopsis seedlings on different concentrations of the drug and assessed the impact on growth
Subsequent experiments using seedlings expressing green fluorescent protein (GFP):F-actin binding domain of fimbrin1 (FABD) (Ketelaar et al, 2004), we determined that 5 mM was a suitable concentration for short-term jasplakinolide treatments

Summary

Introduction

The cytoskeleton supports many fundamental cellular processes, including morphogenesis, cell division, and vesicle trafficking (Goode et al, 2000; Fu et al, 2005; Collings, 2008; Gutierrez et al, 2009; Petrasek and Schwarzerova , 2009; Szymanski, 2009). Coalignment of AFs and MTs was observed in Taricha granulosa (newt) lung epithelial cells (Salmon et al, 2002), and MTs were transported in association with AFs to sites of induced wounding in Xenopus laevis oocytes (Mandato and Bement, 2003). Fine transverse AFs have been observed as an ordered array, reminiscent of the transverse arrangements of MTs (Collings and Wasteneys, 2005), and AFs and MTs have been observed to coalign (Traas et al, 1987; Blancaflor, 2000; Collings and Wasteneys, 2005; Barton and Overall, 2010). Reorientation of the MT array was concurrent with changes in AF organization in tracheary elements of developing Zinna elegans cells (Kobayashi et al, 1988), and disruption of the AFs impaired MT reorganization, an effect that was observed in azuki bean (Vigna angularis) cells (Takesue and Shibaoka, 1998)

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