Plant Physiol. PAM Fluorometers & Gas Exchange
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH
QUICK SEARCH:   [advanced]


     

Plant Physiology Preview
Published on December 27, 2007; 10.1104/pp.107.110270

This Article
Right arrow Full Text (Plant Physiology Preview (PDF))
Right arrow Supplemental Data
Right arrow All Versions of this Article:
146/3/1142    most recent
pp.107.110270v1
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Chevalier, F.
Right arrow Articles by Vachon, G.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Chevalier, F.
Right arrow Articles by Vachon, G.
Agricola
Right arrow Articles by Chevalier, F.
Right arrow Articles by Vachon, G.

Received October 4, 2007
Accepted December 23, 2007

GeBP and GeBP-like proteins are non-canonical leucine-zipper transcription factors that regulate cytokinin response in Arabidopsis thaliana

Florian Chevalier , Daniel Perazza , Frederic Laporte , Gaelle Le Henanff , Patricia Hornitschek , Jean-Marc Bonneville , Michel Herzog , and Gilles Vachon *

Laboratoire Plastes et Differenciation Cellulaire, CNRS FRE 3017, Universite J. Fourier Bat. CERMO, 3eme etage, BP 53X 38041 Grenoble, France

* Corresponding author; email: gilles.vachon{at}ujf-grenoble.fr.

Understanding the role of transcription factors (TFs) is essential in reconstructing developmental regulatory networks. The plant-specific GeBP TF family of Arabidopsis (Arabidopsis thaliana) comprises 21 members, all of unknown function. A subset of four members, the founding member GeBP and GeBP-like proteins (GPL) 1, 2 to 3, share a conserved C-terminal domain. Here we report that GeBP/ GPL genes represent a newly defined class of leucine-zipper TF and that they play a redundant role in cytokinin hormone pathway regulation. Specifically, we demonstrate using yeast, in vitro and split-yellow fluorescent protein in planta assays that GeBP/GPL proteins form homo and heterodimers through a non-canonical leucine-zipper motif located in the C-terminal domain. A triple loss-of-function mutant of the three most closely related genes gebp gpl1 gpl2 shows a reduced sensitivity to exogenous cytokinins in a subset of cytokinin responses such as senescence and growth while root inhibition is not affected. We find that transcript levels of type-A cytokinin response genes, which are involved in the negative feed-back regulation of cytokinin signalling, are higher in the triple mutant. Using a GPL version that act as a constitutive transcriptional activator, we show that the regulation of ARRs is mediated by at least one additional, as yet unknown, repressor acting genetically downstream in the GeBP/GPL pathway. Our results indicate that GeBP/GPL genes encode a new class of unconventional leucine-zipper TF proteins and suggest that their role in the cytokinin pathway is to antagonize the negative feedback regulation on ARR genes to trigger the cytokinin response.






HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH
ASPB Publications PLANT PHYSIOLOGY THE PLANT CELL
Copyright © 2007 by the American Society of Plant Biologists