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Plastid sedimentation kinetics in roots of wild-type and starch-deficient mutants of ArabidopsisSedimentation and movement of plastids in columella cells of the root cap were measured in seedlings of wild-type, a reduced starch mutant, and a starchless mutant of Arabidopsis. To assay for sedimentation, we used both linear measurements and the change of angle from the cell center as indices in vertical and reoriented plants with the aid of computer-assisted image analysis. Seedlings were fixed at short periods after reorientation, and plastid sedimentation correlated with starch content in the three strains of Arabidopsis. Amyloplasts of wild-type seedlings showed the greatest sedimentation, whereas plastids of the starchless mutant showed no significant sedimentation in the vertically grown and reoriented seedlings. Because previous research has shown that a full complement of starch is needed for full gravitropic sensitivity, this study correlates increased sensitivity with plastid sedimentation. However, although plastid sedimentation contributed to gravisensitivity, it was not required, because the gravitropic starchless mutant had plastids that did not sediment. This is the first study, to our knowledge, to measure plastid sedimentation in Arabidopsis roots after reorientation of seedlings. Taken together, the results of this study are consistent with the classic plastid-based and protoplast-based models of graviperception and suggest that multiple systems of perception exist in plant cells.
Document ID
20040141971
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
MacCleery, S. A.
(Miami University Oxford, Ohio 45056, United States)
Kiss, J. Z.
Date Acquired
August 22, 2013
Publication Date
May 1, 1999
Publication Information
Publication: Plant physiology
Volume: 120
Issue: 1
ISSN: 0032-0889
Subject Category
Life Sciences (General)
Distribution Limits
Public
Copyright
Other
Keywords
NASA Discipline Plant Biology
Non-NASA Center

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