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Geoperception in primary and lateral roots of Phaseolus vulgaris (Fabaceae). III. A model to explain the differential georesponsiveness of primary and lateral rootsHalf-tipped primary and lateral roots of Phaseolus vulgaris bend toward the side of the root on which the intact half tip remains. Therefore, tips of lateral and primary roots produce growth effectors capable of inducing gravicurvature. The asymmetrical placement of a tip of a lateral root onto a detipped primary root results in the root bending toward the side of the root onto which the tip was placed. That is, the lesser graviresponsiveness of lateral roots as compared with primary roots is not due to the inability of their caps to produce growth inhibitors. The more pronounced graviresponsiveness of primary roots is positively correlated with the presence of columella tissues that are 3.8 times longer, 1.7 times wider, and 10.5 times more voluminous than the columellas of lateral roots. We propose that the lack of graviresponsiveness exhibited by lateral roots is due to the fact that they (i) produce smaller amounts of the inhibitor than primary (i.e., strongly graviresponsive) roots and (ii) are unable to redistribute the inhibitor so as to be able to create a concentration gradient sufficient to induce a pronounced gravitropic response.
Document ID
20040089564
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Ransom, J. S.
(Baylor University Waco, TX 76798, United States)
Moore, R.
Date Acquired
August 21, 2013
Publication Date
January 1, 1985
Publication Information
Publication: Canadian journal of botany
Volume: 63
ISSN: 0008-4026
Subject Category
Life Sciences (General)
Distribution Limits
Public
Copyright
Other
Keywords
NASA Program Space Biology
Non-NASA Center
NASA Discipline Plant Biology
NASA Discipline Number 40-10

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