NTRS - NASA Technical Reports Server

Back to Results
Disruption of the actin cytoskeleton results in the promotion of gravitropism in inflorescence stems and hypocotyls of ArabidopsisThe actin cytoskeleton is hypothesized to play a major role in gravity perception and transduction mechanisms in roots of plants. To determine whether actin microfilaments (MFs) are involved in these processes in stem-like organs, we studied gravitropism in Arabidopsis inflorescence stems and hypocotyls. Localization studies using Alexa Fluor-phalloidin in conjugation with confocal microscopy demonstrated a longitudinally and transversely oriented actin MF network in endodermal cells of stems and hypocotyls. Latrunculin B (Lat-B) treatment of hypocotyls caused depolymerization of actin MFs in endodermal cells and a significant reduction of hypocotyl growth rates. Actin MFs in Lat-B-treated inflorescence stems also were disrupted, but growth rates were not affected. Despite disruption of the actin cytoskeleton in these two organs, Lat-B-treated stems and hypocotyls exhibited a promotion of gravitropic curvature in response to reorientation. In contrast, Lat-B reduced gravitropic curvature in roots but also reduced the growth rate. Thus, in contrast to prevailing hypotheses, our results suggest that actin MFs are not a necessary component of gravitropism in inflorescence stems and hypocotyls. Furthermore, this is the first study to demonstrate a prominent actin MF network in endodermal cells in the putative gravity-perceiving cells in stems.
Document ID
Document Type
Reprint (Version printed in journal)
External Source(s)
Yamamoto, Kazuyoshi
(Miami University Oxford, Ohio 45056)
Kiss, John Z.
Date Acquired
August 21, 2013
Publication Date
February 1, 2002
Publication Information
Publication: Plant physiology
Volume: 128
Issue: 2
ISSN: 0032-0889
Subject Category
Life Sciences (General)
Funding Number(s)
CONTRACT_GRANT: 1R15 GM 57806-01
Distribution Limits
NASA Discipline Plant Biology
Non-NASA Center

Available Downloads

There are no available downloads for this record.
No Preview Available