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How cereal grass shoots perceive and respond to gravityThe leaf-sheath pulvinus of grasses presents a unique system for studying gravitropism, primarily because of its differences from other organs. The mature pulvinus is a discrete organ specialized for gravitropism: it is nongrowing in the absence of gravistimulation and capable of displaying a graviresponse independent of the rest of the plant. In this paper we present a model for gravitropism in pulvini based on recent findings from studies on the mechanisms of graviperception and graviresponse. According to this model, amyloplasts play an essential role in perceiving a change in the orientation of the pulvinus. The perception of this reorientation leads to the enhanced synthesis and release from conjugate of the auxin IAA, and the increased conjugation of gibberellin, on a localized basis. Because there is a graded growth promotion across the gravistimulated pulvinus, it is suggested that the observed hormonal asymmetry is actually an indication of a linear gradient of hormone concentration, as well as hormone response, across the pulvinus. It is further suggested that the linear gradient of hormone concentration may be predominantly the result of local changes in hormone level, rather than a product of hormonal movement into or across the pulvinus.
Document ID
20040089850
Acquisition Source
Headquarters
Document Type
Reprint (Version printed in journal)
Authors
Kaufman, P. B.
(University of Michigan Ann Arbor 48109, United States)
Brock, T. G.
Song, I.
Rho, Y. B.
Ghosheh, N. S.
Date Acquired
August 21, 2013
Publication Date
January 1, 1987
Publication Information
Publication: American journal of botany
Volume: 74
Issue: 9
ISSN: 0002-9122
Subject Category
Life Sciences (General)
Funding Number(s)
CONTRACT_GRANT: NAGW-34
Distribution Limits
Public
Copyright
Other
Keywords
NASA Discipline Number 40-99
NASA Discipline Plant Biology
NASA Program Space Biology Research Associates
NASA Discipline Number 40-10
Review
Review, Tutorial
Non-NASA Center
NASA Program Space Biology

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