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Sugar demand, not auxin, is the initial regulator of apical dominance


Mason, MG and Ross, JJ and Babst, BA and Wienclaw, BN and Beveridge, CA, Sugar demand, not auxin, is the initial regulator of apical dominance, Proceedings of the National Academy of Sciences of The United States of America., 111, (16) pp. 6092-6097. ISSN 0027-8424 (2014) [Refereed Article]

Copyright Statement

Copyright 2014 The Authors

DOI: doi:10.1073/pnas.1322045111


For almost a century the plant hormone auxin has been central to theories on apical dominance, whereby the growing shoot tip suppresses the growth of the axillary buds below. According to the classic model, the auxin indole-3-acetic acid is produced in the shoot tip and transported down the stem, where it inhibits bud growth. We report here that the initiation of bud growth after shoot tip loss cannot be dependent on apical auxin supply because we observe bud release up to 24 h before changes in auxin content in the adjacent stem. After the loss of the shoot tip, sugars are rapidly redistributed over large distances and accumulate in axillary buds within a timeframe that correlates with bud release. Moreover, artificially increasing sucrose levels in plants represses the expression of BRANCHED1 (BRC1), the key transcriptional regulator responsible for maintaining bud dormancy, and results in rapid bud release. An enhancement in sugar supply is both necessary and sufficient for suppressed buds to be released from apical dominance. Our data support a theory of apical dominance whereby the shoot tipís strong demand for sugars inhibits axillary bud outgrowth by limiting the amount of sugar translocated to those buds.

Item Details

Item Type:Refereed Article
Keywords:auxin, branching, shoot branching, sink demand, decapitation, girdling, long-distance signaling
Research Division:Biological Sciences
Research Group:Plant biology
Research Field:Plant physiology
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the biological sciences
UTAS Author:Ross, JJ (Associate Professor John Ross)
ID Code:93814
Year Published:2014
Web of Science® Times Cited:310
Deposited By:Plant Science
Deposited On:2014-08-19
Last Modified:2017-11-02

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