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Attempts to Localize and Identify the Gravity-sensing Device of Plant SeedlingsThe growth hormone asymmetry develops within three minutes following the initiation of the gravitational asymmetry and radio-labeled compounds being transported from the seed to the shoot also show asymmetric distribution. It is found that the target of the gravity stimulus resides primarily in the permability of the vascular tissue that regulates the supply of hormone to the surrounding tissues. It is hypothesized that the gravitational stimulus induces an asymmetric change in the rate of secretion of the growth hormone, IAA, from the vascular tissue into the surrounding cortical cells. More hormone would be secreted from the vascular stele proximal to the lower side of a horizontally placed plant shoot than from the upper side. This results in more growth hormone in the lower cortical (plus epidermal) cells, and ultimately more growth, such that the plant grows asymmetrically and, ultimately attain its normal vertical orientation. A theory was developed of how plants respond to the gravitational stimulus. The theory is based upon the analytical results concerning the effects of gravity on the distribution of the plant growth hormone, IAA, in both its free and conjugated forms, and upon the effect of the growth stimulis on the distribution of externally applied radio-labeled compounds. Its advantage is that it is testable and that it is built upon solid knowledge of the effects of the gravitational stimulus upon the endogenous growth hormone, IAA, and upon the distribution of externally applied radio-labeled compounds.
Document ID
19850017753
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Bandurski, R. S.
(Michigan State Univ. East Lansing, MI, United States)
Schulze, A.
(Michigan State Univ. East Lansing, MI, United States)
Momonoki, Y.
(Michigan State Univ. East Lansing, MI, United States)
Desrosiers, M.
(Michigan State Univ. East Lansing, MI, United States)
Fearn-Desrosiers, D.
(Michigan State Univ. East Lansing, MI, United States)
Date Acquired
August 12, 2013
Publication Date
April 1, 1985
Publication Information
Publication: NASA. Washington NASA Space Biol. Program:
Subject Category
Life Sciences (General)
Accession Number
85N26064
Funding Number(s)
CONTRACT_GRANT: NAGW-97
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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