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Correlations between gravitropic curvature and auxin movement across gravistimulated roots of Zea maysWe compared the kinetics of auxin redistribution across the caps of primary roots of 2-day-old maize (Zea mays, cv Merit) seedlings with the time course of gravitropic curvature. [3H] indoleacetic acid was applied to one side of the cap in an agar donor and radioactivity moving across the cap was collected in an agar receiver applied to the opposite side. Upon gravistimulation the roots first curved upward slightly, then returned to the horizontal and began curving downward, reaching a final angle of about 67 degrees. Movement of label across the caps of gravistimulated roots was asymmetric with preferential downward movement (ratio downward/upward = ca. 1.6, radioactivity collected during the 90 min following beginning of gravistimulation). There was a close correlation between the development of asymmetric auxin movement across the root cap and the rate of curvature, with both values increasing to a maximum and then declining as the roots approached the final angle of curvature. In roots preadapted to gravity (alternate brief stimulation on opposite flanks over a period of 1 hour) the initial phase of upward curvature was eliminated and downward bending began earlier than for controls. The correlation between asymmetric auxin movement and the kinetics of curvature also held in comparisons between control and preadapted roots. Both downward auxin transport asymmetry and downward curvature occurred earlier in preadapted roots than in controls. These findings are consistent with suggestions that the root cap is not only the site of perception but also the location of the initial redistribution of effectors that ultimately leads to curvature.
Document ID
20040090226
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Young, L. M.
(Ohio Northern University Ada 45810, United States)
Evans, M. L.
Hertel, R.
Date Acquired
August 21, 2013
Publication Date
January 1, 1990
Publication Information
Publication: Plant physiology
Volume: 92
ISSN: 0032-0889
Subject Category
Life Sciences (General)
Funding Number(s)
CONTRACT_GRANT: DMB8608673
CONTRACT_GRANT: NAGW2-97
Distribution Limits
Public
Copyright
Other
Keywords
NASA Discipline Number 29-20
Non-NASA Center
NASA Discipline Plant Biology
NASA Program Space Biology

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