Curvature in Arabidopsis inflorescence stems is limited to the region of amyloplast displacement

Gravitropic sensing in stems and stem-like organs is hypothesized to occur in the endodermis. However, since the endodermis runs the entire length of the stem, the precise site of gravisensing has been difficult to define. In this investigation of gravisensitivity in inflorescence stems of Arabidops...

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Bibliographic Details
Published in:Plant and cell physiology 2000-06, Vol.41 (6), p.702-709
Main Authors: Weise, S.E. (Miami Univ., Oxford (USA)), Kuznetsov, O.A, Hasenstein, K.H, Kiss, J.Z
Format: Article
Language:English
Subjects:
ALMIDON
AMIDON
Amyloplast
ARABIDOPSIS
Arabidopsis - anatomy & histology
Arabidopsis - physiology
Arabidopsis - radiation effects
CAMPO MAGNETICO
CHAMP MAGNETIQUE
Gravitropism
Gravitropism - physiology
Life Sciences (General)
MAGNETIC FIELD
Magnetics
Magnetophoresis
Plant Stems - cytology
Plant Stems - physiology
Plant Stems - radiation effects
PLASTE
PLASTIDIOS
PLASTIDS
Signal transduction
Space life sciences
STARCH
Statolith
STEMS
TALLO
TIGE
TROPISME
TROPISMO
TROPISMS
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Summary:Gravitropic sensing in stems and stem-like organs is hypothesized to occur in the endodermis. However, since the endodermis runs the entire length of the stem, the precise site of gravisensing has been difficult to define. In this investigation of gravisensitivity in inflorescence stems of Arabidopsis, we positioned stems in a high gradient magnetic field (HGMF) on a rotating clinostat. Approximately 40% of the young, wild-type (WT) inflorescences, for all positions tested, curved toward the HGMF in the vicinity of the stem exposed to the field. In contrast, when the wedge was placed in the basal region of older inflorescence stems, no curvature was observed. As a control, the HGMF was applied to a starchless mutant, and 5% of the stems curved toward the field. Microscopy of the endodermis in the WT showed amyloplast displacement in the vicinity of the HGMF. Additional structural studies demonstrated that the basal region of WT stems experienced amyloplast displacement and, therefore, suggest this region is capable of gravity perception. However, increased lignification likely prevented curvature in the basal region. The lack of apical curvature after basal amyloplast displacement indicates that gravity perception in the base is not transmitted to the apex. Thus, these results provide evidence that the signal (and thus, response) resulting from perception in Arabidopsis inflorescence stems is spatially restricted.
ISSN:0032-0781
1471-9053
DOI:10.1093/pcp/41.6.702