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Auxin acts independently of DELLA proteins in regulating gibberellin levels


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Reid, JB and Davidson, SE and Ross, JJ (2011) Auxin acts independently of DELLA proteins in regulating gibberellin levels. Plant Signaling & Behavior, 6 (3). pp. 406-408. ISSN 1559-2316

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Shoot elongation is a vital process for plant development and productivity, in both ecological and economic contexts. Auxin and bioactive gibberellins (GAs), such as GA1, play critical roles in the control of elongation,1-3 along with environmental and endogenous factors, including other hormones such as the brassinosteroids.4,5 The effect of auxins, such as indole-3-acetic acid (IAA), is at least in part mediated by its effect on GA metabolism,6 since auxin upregulates biosynthesis genes such as GA 3-oxidase and GA 20-oxidase and downregulates GA catabolism genes such as GA 2-oxidases, leading to elevated levels of bioactive GA1.7 In our recent paper,1 we have provided evidence that this action of IAA is largely independent of DELLA proteins, the negative regulators of GA action,8,9 since the auxin effects are still present in the DELLA-deficient la cry-s genotype of pea. This was a crucial issue to resolve, since like auxin, the DELLAs also promote GA1 synthesis and inhibit its deactivation. DELLAs are deactivated by GA, and thereby mediate a feedback system by which bioactive GA regulates its own level.10 However, our recent results,1 in themselves, do not show the generality of the auxin-GA relationship across species and phylogenetic groups or across different tissue types and responses. Further, they do not touch on the ecological benefits of the auxin-GA interaction. These issues are discussed below as well as the need for the development of suitable experimental systems to allow this process to be examined.

Item Type: Article
Journal or Publication Title: Plant Signaling & Behavior
Page Range: pp. 406-408
ISSN: 1559-2316
Identification Number - DOI: 10.4161/psb.6.3.14352
Additional Information: Licenced under Creative Commons Attribution-NonCommercial 3.0 Unported (CC BY-NC 3.0)
Date Deposited: 10 Feb 2012 04:39
Last Modified: 18 Nov 2014 04:27
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