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A non‐ DNA ‐binding activity for the ATHB 4 transcription factor in the control of vegetation proximity
Author(s) -
Gallemí Marçal,
MolinaContreras Maria Jose,
Paulišić Sandi,
SallaMartret Mercè,
Sorin Céline,
Godoy Marta,
FrancoZorrilla Jose Manuel,
Solano Roberto,
MartínezGarcía Jaime F.
Publication year - 2017
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.14727
Subject(s) - transcription factor , arabidopsis , biology , homeobox , microbiology and biotechnology , arabidopsis thaliana , hypocotyl , repressor , phytochrome , dna binding protein , psychological repression , binding site , wrky protein domain , genetics , gene , botany , mutant , gene expression , red light
Summary In plants, perception of vegetation proximity by phytochrome photoreceptors activates a transcriptional network that implements a set of responses to adapt to plant competition, including elongation of stems or hypocotyls. In Arabidopsis thaliana , the homeodomain‐leucine zipper ( HD ‐Zip) transcription factor ARABIDOPSIS THALIANA HOMEOBOX 4 (ATHB4) regulates this and other responses, such as leaf polarity. To better understand the shade regulatory transcriptional network, we have carried out structure–function analyses of ATHB 4 by overexpressing a series of truncated and mutated forms and analyzing three different responses: hypocotyl response to shade, transcriptional activity and leaf polarity. Our results indicated that ATHB 4 has two physically separated molecular activities: that performed by HD ‐Zip, which is involved in binding to DNA ‐regulatory elements, and that performed by the ETHYLENE‐RESPONSIVE ELEMENT BINDING FACTOR‐associated amphiphilic repression ( EAR )‐containing N‐terminal region, which is involved in protein−protein interaction. Whereas both activities are required to regulate leaf polarity, DNA ‐binding activity is not required for the regulation of the seedling responses to plant proximity, which indicates that ATHB 4 works as a transcriptional cofactor in the regulation of this response. These findings suggest that transcription factors might employ alternative mechanisms of action to regulate different developmental processes.