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The hormonal regulation of axillary bud growth in Arabidopsis

Chatfield, S.P., Stirnberg, P., Forde, B.G. and Leyser, O. (2000) The hormonal regulation of axillary bud growth in Arabidopsis. The Plant Journal, 24 (2). pp. 159-169. ISSN 0960-7412

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Abstract

Apically derived auxin has long been known to inhibit lateral bud growth, but since it appears not to enter the bud, it has been proposed that its inhibitory effect is mediated by a second messenger. Candidates include the plant hormones ethylene, cytokinin and abscisic acid. We have developed a new assay to study this phenomenon using the model plant Arabidopsis. The assay allows study of the effects of both apical and basal hormone applications on the growth of buds on excised nodal sections. We have shown that apical auxin can inhibit the growth of small buds, but larger buds were found to have lost competence to respond. We have used the assay with nodes from wild-type and hormone-signalling mutants to test the role of ethylene, cytokinin and abscisic acid in bud inhibition by apical auxin. Our data eliminate ethylene as a second messenger for auxin-mediated bud inhibition. Similarly, abscisic acid signalling is not to be required for auxin action, although basally applied abscisic can enhance inhibition by apical auxin and apically applied abscisic acid can reduce it. By contrast, basally applied cytokinin was found to release lateral buds from inhibition by apical auxin, while apically applied cytokinin dramatically increased the duration of inhibition. These results are consistent with cytokinin acting independently to regulate bud growth, rather than as a second messenger for auxin. However, in the absence of cytokinin-signalling mutants, a role for cytokinin as a second messenger for auxin cannot be ruled out.

Item Type: Article
Copyright, Publisher and Additional Information: Open access copy available from the journal web site.
Keywords: auxin, apical dominance, bud growth, ethylene, abscisic acid, cytokinin
Institution: The University of York
Academic Units: The University of York > Biology (York)
Depositing User: Open Access From Journal
Date Deposited: 22 Dec 2008 14:57
Last Modified: 22 Dec 2008 14:57
Published Version: http://dx.doi.org/10.1046/j.1365-313x.2000.00862.x
Status: Published
Publisher: Wiley-Blackwell
Refereed: Yes
Identification Number: 10.1046/j.1365-313x.2000.00862.x
URI: http://eprints.whiterose.ac.uk/id/eprint/5110

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