Poster: Cytoskeleton structure & dynamics

Abs # 677: Spatio-temporal imaging of F-actin dynamics in developing roots using green fluorescent protein fusions to Arabidopsis Fimbrin 1

Presenter:	Wang, Yuh-Shuh , yswang@noble.org
Authors	Wang, Yuh-Shuh  (A)   Motes, Christy M. (A)   Blancaflor, Elison B. (A)
Affiliations:	(A): The Samuel Roberts Noble Foundation

Green fluorescent protein (GFP) has brought new insights into the function of the plant cytoskeleton since protein fusions with GFP that bind to microtubules or actin filaments (F-actin) have allowed researchers to visualize these major cytoskeletal components in living plant cells. For studies on actin, GFP fusions to the actin binding domain (ABD) of talin have been the most popular reporter. Although GFP-Talin has allowed in vivo actin imaging in a variety of plant cells, its utility in monitoring actin dynamics in stably transformed plants is limited. In this paper, we created a variety of GFP fusions to Arabidopsis fimbrin1 (AtFim1) to explore their utility for in vivo F-actin imaging and to better understand the actin binding properties of AtFim1 in living plant cells. Translational fusions of GFP to full length AtFim1 or to truncated variants of AtFim1 showed interesting localization patterns in transient expression assays. A truncated AtFim1-GFP fusion that contained the 27 conserved amino acids that make up the putative actin binding site of ABD1 and ABD2 was capable of labeling distinct filaments in stably transformed Arabidopsis roots. The filaments decorated by this construct were highly dynamic in growing root hairs and elongating root cells and were sensitive to actin disrupting drugs. Thus, the fimbrin-GFP reporters we describe here provide additional tools for studying the actin cytoskeleton during root cell development. Moreover, the localization of AtFim1-GFP provides insights into the regulation of actin organization in developing roots by this class of actin cross-linking proteins (This work was supported by NASA grant NAG 2-1518 to EBB).