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Bell-like homeodomain selectively regulates the high-irradiance response of phytochrome A.

Authors :
Staneloni RJ
Rodriguez-Batiller MJ
Legisa D
Scarpin MR
Agalou A
Cerdán PD
Meijer AH
Ouwerkerk PB
Casal JJ
Source :
Proceedings of the National Academy of Sciences of the United States of America [Proc Natl Acad Sci U S A] 2009 Aug 11; Vol. 106 (32), pp. 13624-9. Date of Electronic Publication: 2009 Jul 28.
Publication Year :
2009

Abstract

Plant responses mediated by phytochrome A display a first phase saturated by transient light signals and a second phase requiring sustained excitation with far-red light (FR). These discrete outcomes, respectively so-called very-low-fluence response (VLFR) and high-irradiance response (HIR), are appropriate in different environmental and developmental contexts but the mechanisms that regulate the switch remain unexplored. Promoter analysis of a light-responsive target gene revealed a motif necessary for HIR but not for VLFR. This motif is required for binding of the Bell-like homeodomain 1 (BLH1) to the promoter in in vitro and in yeast 1-hybrid experiments. Promoter substitutions that increased BLH1 binding also enhanced HIR. blh1 mutants showed reduced responses to continuous FR and to deep canopy shadelight, but they retained normal responses to pulsed FR or red light and unfiltered sunlight. BLH1 enhanced BLH1 expression and its promotion by FR. We conclude that BLH1 specifically regulates HIR and not VLFR of phytochrome A.

Details

Language :
English
ISSN :
1091-6490
Volume :
106
Issue :
32
Database :
MEDLINE
Journal :
Proceedings of the National Academy of Sciences of the United States of America
Publication Type :
Academic Journal
Accession number :
19666535
Full Text :
https://doi.org/10.1073/pnas.0906598106