TIR1/AFB-Aux/IAA auxin perception mediates rapid cell wall acidification and growth of Arabidopsis hypocotyls

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Abstract

Despite being composed of immobile cells, plants reorient along directional stimuli. The hormone auxin is redistributed in stimulated organs leading to differential growth and bending. Auxin application triggers rapid cell wall acidification and elongation of aerial organs of plants, but the molecular players mediating these effects are still controversial. Here we use genetically-encoded pH and auxin signaling sensors, pharmacological and genetic manipulations available for Arabidopsis etiolated hypocotyls to clarify how auxin is perceived and the downstream growth executed. We show that auxin-induced acidification occurs by local activation of H⁺-ATPases, which in the context of gravity response is restricted to the lower organ side. This auxin-stimulated acidification and growth require TIR1/AFB-Aux/IAA nuclear auxin perception. In addition, auxin-induced gene transcription and specifically SAUR proteins are crucial downstream mediators of this growth. Our study provides strong experimental support for the acid growth theory and clarified the contribution of the upstream auxin perception mechanisms.

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Matyáš Fendrych

Institute of Science and Technology Austria, Klosterneuburg, Austria

Competing interests
The authors declare that no competing interests exist.
Jeffrey Leung

Institut Jean-Pierre Bourgin, UMR1318 INRA-AgroParisTech, Versailles, France

Competing interests
The authors declare that no competing interests exist.
Jiří Friml

Institute of Science and Technology Austria, Klosterneuburg, Austria

For correspondence
jiri.friml@ist.ac.at

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0002-8302-7596

Funding

European Research Council (project ERC-2011-StG-20101109-PSDP)

Jiří Friml

Marie Curie Actions FP7 2007-2013 (REA grant agreement n.291734)

Matyáš Fendrych

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

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This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.