Sources of Free IAA in the Mesocotyl of Etiolated Maize Seedlings

Sources of free indole-3-acetic acid (IAA) for the mesocotyl of intact etiolized maize ((Zea mays L.) seedlings are evaluated. The coleoptile unit, which includes the primary leaves and the coleoptilar node, is the main source of free IAA for the mesocotyl. The seed and the roots are not immediate s...

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Published inPlant physiology (Bethesda) Vol. 69; no. 5; pp. 1109 - 1112
Main Authors Iino, Moritoshi, Carr, Denis J.
Format Journal Article
LanguageEnglish
Published United States American Society of Plant Physiologists 01.05.1982
Subjects
Auxins
Coleoptiles
Corn
Decapitation
Mesocotyls
Metabolism
Oats
Plant growth regulators
Plants
Seedlings
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Summary:Sources of free indole-3-acetic acid (IAA) for the mesocotyl of intact etiolized maize ((Zea mays L.) seedlings are evaluated. The coleoptile unit, which includes the primary leaves and the coleoptilar node, is the main source of free IAA for the mesocotyl. The seed and the roots are not immediate sources of IAA supply. Dependence of the apical growing region of the mesocotyl on the coleoptile unit as a source of free IAA is almost total. One-half or more of the supply of IAA comes from the coleoptile tip, the rest mainly from the primary leaves. Removal of the coleoptile tip results in inhibition of mesocotyl elongation. The hypothesis that growth of the mesocotyl is regulated by auxin supplied by the coleoptile is supported. Conjugated forms of IAA appear to play little part in regulating the levels of free IAA in the shoot.
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Present address: Department of Plant Biology, Carnegie Institution of Washington, 290 Panama Street, Stanford, CA 94305.
ISSN:0032-0889
1532-2548
DOI:10.1104/pp.69.5.1109