Document Detail

Regulation of phytochrome B signaling by phytochrome A and FHY1 in Arabidopsis thaliana.
MedLine Citation:
PMID:  10417700     Owner:  NLM     Status:  MEDLINE    
Phytochrome A (phyA) and phytochrome B (phyB) share the control of many processes but little is known about mutual signaling regulation. Here, we report on the interactions between phyA and phyB in the control of the activity of an Lhcb1*2 gene fused to a reporter, hypocotyl growth and cotyledon unfolding in etiolated Arabidopsis thaliana. The very-low fluence responses (VLFR) induced by pulsed far-red light and the high-irradiance responses (HIR) observed under continuous far-red light were absent in the phyA and phyA phyB mutants, normal in the phyB mutant, and reduced in the fhy1 mutant that is defective in phyA signaling. VLFR were also impaired in Columbia compared to Landsberg erecta. The low-fluence responses (LFR) induced by red-light pulses and reversed by subsequent far-red light pulses were small in the wild type, absent in phyB and phyA phyB mutants but strong in the phyA and fhy1 mutants. This indicates a negative effect of phyA and FHY1 on phyB-mediated responses. However, a pre-treatment with continuous far-red light enhanced the LFR induced by a subsequent red-light pulse. This enhancement was absent in phyA, phyB, or phyA phyB and partial in fhy1. The levels of phyB were not affected by the phyA or fhy1 mutations or by far-red light pre-treatments. We conclude that phyA acting in the VLFR mode (i.e. under light pulses) is antagonistic to phyB signaling whereas phyA acting in the HIR mode (i.e. under continuous far-red light) operates synergistically with phyB signaling, and that both types of interaction require FHY1.
P D Cerdán; M J Yanovsky; F C Reymundo; A Nagatani; R J Staneloni; G C Whitelam; J J Casal
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The Plant journal : for cell and molecular biology     Volume:  18     ISSN:  0960-7412     ISO Abbreviation:  Plant J.     Publication Date:  1999 Jun 
Date Detail:
Created Date:  1999-12-09     Completed Date:  1999-12-09     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  9207397     Medline TA:  Plant J     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  499-507     Citation Subset:  IM; S    
Instituto de Investigaciones Bioquímicas Fundación Campomar, Buenos Aires, Argentina.
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MeSH Terms
Arabidopsis / physiology*,  radiation effects
Arabidopsis Proteins
Dose-Response Relationship, Radiation
Genes, Reporter
Light-Harvesting Protein Complexes*
Photoreceptor Cells*
Photosynthetic Reaction Center Complex Proteins / biosynthesis
Photosystem II Protein Complex*
Phytochrome / isolation & purification,  metabolism*
Phytochrome A
Phytochrome B
Plants, Genetically Modified
Signal Transduction
Species Specificity
Transcription Factors*
Reg. No./Substance:
0/Arabidopsis Proteins; 0/Light-Harvesting Protein Complexes; 0/PHYA protein, Arabidopsis; 0/PHYB protein, Arabidopsis; 0/Photosynthetic Reaction Center Complex Proteins; 0/Photosystem II Protein Complex; 0/Phytochrome A; 0/Transcription Factors; 0/chlorophyll a-b-binding protein, Ginkgo biloba; 11121-56-5/Phytochrome; 136250-22-1/Phytochrome B

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