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Polar transport of auxin across gravistimulated roots of maize and its enhancement by calciumThe effect of Ca on the polar movement of [3H]indoleacetic acid ([3H]IAA) in gravistimulated roots was examined using 3-day-old seedlings of maize (Zea mays L.). Transport of label was measured by placing an agar donor block containing [3H]IAA on one side of the elongation zone and measuring movement of label across the root into an agar receiver block on the opposite side. In vertically oriented roots, movement of label across the elongation zone into the receiver was slight and was not enhanced by incorporating 10 millimolar CaCl2 into the receiver block. In horizontally oriented roots, movement of label across the root was readily detectable and movement to a receiver on the bottom was about 3-fold greater than movement in the opposite direction. This polarity was abolished in roots from which the caps were removed prior to gravistimulation. When CaCl2 was incorporated into the receivers, movement of label across horizontally oriented intact roots was increased about 3-fold in both the downward and upward direction. The ability of Ca to enhance the movement of label from [3H]IAA increased with increasing Ca concentration in the receiver up to 5 to 10 millimolar CaCl2. With the inclusion of CaCl2 in the receiver blocks, gravity-induced polar movement of label into receiver blocks from applied [3H]IAA was detectable within 30 minutes, and asymmetric distribution of label within the tissue was detectable within 20 minutes. The results indicate that gravistimulation induces a physiological asymmetry in the auxin transport system of maize roots and that Ca increases the total transport of auxin across the root.
Document ID
20040089858
Acquisition Source
Headquarters
Document Type
Reprint (Version printed in journal)
Authors
Lee, J. S.
(Ohio State University Columbus 43210, United States)
Evans, M. L.
Date Acquired
August 21, 2013
Publication Date
January 1, 1985
Publication Information
Publication: Plant physiology
Volume: 77
ISSN: 0032-0889
Subject Category
Life Sciences (General)
Funding Number(s)
CONTRACT_GRANT: PCM 8305775
CONTRACT_GRANT: NAGW-297
Distribution Limits
Public
Copyright
Other
Keywords
NASA Program Space Biology
NASA Discipline Plant Biology
NASA Discipline Number 40-10
Non-NASA Center

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