Gene Symbol: HFR1
Description: basic helix-loop-helix (bHLH) DNA-binding superfamily protein
Alias: FBI1, LONG HYPOCOTYL IN FAR-RED, REDUCED PHYTOCHROME SIGNALING 1, REDUCED SENSITIVITY TO FAR-RED LIGHT 1, REP1, RSF1, T6A9.4, T6A9_4, basic helix-loop-helix (bHLH) DNA-binding superfamily protein
Species: thale cress

Top Publications

  1. Kim Y, Woo J, Song P, Soh M. HFR1, a phytochrome A-signalling component, acts in a separate pathway from HY5, downstream of COP1 in Arabidopsis thaliana. Plant J. 2002;30:711-9 pubmed
    b>HFR1, a basic helix-loop-helix protein, is known to be required for a subset of phytochrome A (phyA)-dependent photoresponses...
  2. Jang I, Yang S, Yang J, Chua N. Independent and interdependent functions of LAF1 and HFR1 in phytochrome A signaling. Genes Dev. 2007;21:2100-11 pubmed
    Several positive regulators of phytochrome A signaling--e.g., LAF1, HFR1, and HY5--operate downstream from the photoreceptor, but their relative sites of action in the transduction pathway are unknown...
  3. Jang I, Yang J, Seo H, Chua N. HFR1 is targeted by COP1 E3 ligase for post-translational proteolysis during phytochrome A signaling. Genes Dev. 2005;19:593-602 pubmed
    ..Another positive regulator of photomorphogenesis is HFR1, a basic helix-loop-helix (bHLH) transcription factor...
  4. Yang S, Jang I, Henriques R, Chua N. FAR-RED ELONGATED HYPOCOTYL1 and FHY1-LIKE associate with the Arabidopsis transcription factors LAF1 and HFR1 to transmit phytochrome A signals for inhibition of hypocotyl elongation. Plant Cell. 2009;21:1341-59 pubmed publisher
    ..FHY1-LIKE (FHL), and two transcription factors, LONG AFTER FAR-RED LIGHT1 (LAF1) and LONG HYPOCOTYL IN FAR-RED1 (HFR1)...
  5. Duek P, Elmer M, van Oosten V, Fankhauser C. The degradation of HFR1, a putative bHLH class transcription factor involved in light signaling, is regulated by phosphorylation and requires COP1. Curr Biol. 2004;14:2296-301 pubmed
    ..b>HFR1 (long hypocotyl in far-red light) is a putative transcription factor with a bHLH domain acting downstream of both ..
  6. Yang J, Lin R, Sullivan J, Hoecker U, Liu B, Xu L, et al. Light regulates COP1-mediated degradation of HFR1, a transcription factor essential for light signaling in Arabidopsis. Plant Cell. 2005;17:804-21 pubmed
    ..Long Hypocotyl in Far-Red 1 (HFR1), a basic helix-loop-helix transcription factor, is required for both phytochrome A-mediated far-red and ..
  7. Fairchild C, Schumaker M, Quail P. HFR1 encodes an atypical bHLH protein that acts in phytochrome A signal transduction. Genes Dev. 2000;14:2377-91 pubmed
    ..We describe a new mutant, hfr1 (long hypocotyl in far-red), that exhibits a reduction in seedling responsiveness specifically to continuous far-..
  8. Hyun Y, Lee I. KIDARI, encoding a non-DNA Binding bHLH protein, represses light signal transduction in Arabidopsis thaliana. Plant Mol Biol. 2006;61:283-96 pubmed
    ..The KDR specifically interacted with HFR1, a bHLH protein regulating photomorphogenesis, in yeast two hybrid assay and the kdr-D was epistatic to 35S::HFR1 ..
  9. Yang J, Lin R, Hoecker U, Liu B, Xu L, Wang H. Repression of light signaling by Arabidopsis SPA1 involves post-translational regulation of HFR1 protein accumulation. Plant J. 2005;43:131-41 pubmed
    ..for targeted degradation of a number of photomorphogenesis-promoting factors, including HY5, LAF1, phyA, and HFR1. Distinct light signaling pathways initiated by multiple photoreceptors (including both phytochromes and ..

More Information


  1. Mara C, Huang T, Irish V. The Arabidopsis floral homeotic proteins APETALA3 and PISTILLATA negatively regulate the BANQUO genes implicated in light signaling. Plant Cell. 2010;22:690-702 pubmed publisher
    ..Consistent with a role in light response, we show that the BNQ gene products regulate the function of HFR1 (for LONG HYPOCOTYL IN FAR-RED1), which encodes a bHLH protein that regulates photomorphogenesis through modulating ..
  2. Shi H, Wang X, Mo X, Tang C, Zhong S, Deng X. Arabidopsis DET1 degrades HFR1 but stabilizes PIF1 to precisely regulate seed germination. Proc Natl Acad Sci U S A. 2015;112:3817-22 pubmed publisher
    ..Genetic analysis demonstrates that DET1 functions upstream of long hypocotyl in far-red 1 (HFR1) and phytochrome interacting factor 1 (PIF1), the key positive and negative transcription regulators in seed ..
  3. Galstyan A, Cifuentes Esquivel N, Bou Torrent J, Martinez Garcia J. The shade avoidance syndrome in Arabidopsis: a fundamental role for atypical basic helix-loop-helix proteins as transcriptional cofactors. Plant J. 2011;66:258-67 pubmed publisher
    ..response is inhibited by genes such as PHYTOCHROME RAPIDLY REGULATED 1 (PAR1), PAR2 and LONG HYPOCOTYL IN FR 1 (HFR1), which are transcriptionally induced by low R:FR...
  4. Zhang X, Wu Y, Tobias J, Brunk B, Deitzer G, Liu D. HFR1 is crucial for transcriptome regulation in the cryptochrome 1-mediated early response to blue light in Arabidopsis thaliana. PLoS ONE. 2008;3:e3563 pubmed publisher
    ..They are found in both eukaryotes and prokaryotes as light sensors. Long Hypocotyl in Far-Red 1 (HFR1) has been identified as a positive regulator and a possible transcription factor in both blue and far-red light ..
  5. Bu Q, Castillon A, Chen F, Zhu L, Huq E. Dimerization and blue light regulation of PIF1 interacting bHLH proteins in Arabidopsis. Plant Mol Biol. 2011;77:501-11 pubmed publisher
    ..PIF1 as a bait and identified a group of proteins including PIF1 itself, PIF3 and long hypocotyl in far-red 1 (HFR1), an atypical HLH protein...
  6. Park H, Ding L, Dai M, Lin R, Wang H. Multisite phosphorylation of Arabidopsis HFR1 by casein kinase II and a plausible role in regulating its degradation rate. J Biol Chem. 2008;283:23264-73 pubmed publisher
    Arabidopsis Long Hypocotyl in Far-Red Light 1 (HFR1), a bHLH transcription factor, plays a critical role in promoting seedling photomorphogenesis and in balancing the shade-avoidance response under canopy shade conditions...
  7. Jang I, Henriques R, Chua N. Three transcription factors, HFR1, LAF1 and HY5, regulate largely independent signaling pathways downstream of phytochrome A. Plant Cell Physiol. 2013;54:907-16 pubmed publisher
    Among signaling components downstream of phytochrome A (phyA), HY5, HFR1 and LAF1 are transcription factors that regulate expression of phyA-responsive genes...
  8. Shi H, Zhong S, Mo X, Liu N, Nezames C, Deng X. HFR1 sequesters PIF1 to govern the transcriptional network underlying light-initiated seed germination in Arabidopsis. Plant Cell. 2013;25:3770-84 pubmed publisher
    ..Here, we identify a positive regulator of phyB-dependent seed germination, long hypocotyl in far-red1 (HFR1)...
  9. Kneissl J, Wachtler V, Chua N, Bolle C. OWL1: an Arabidopsis J-domain protein involved in perception of very low light fluences. Plant Cell. 2009;21:3212-25 pubmed publisher
    ..OWL1 interacts with the basic helix-loop-helix HFR1 (LONG HYPOCOTYL IN FAR-RED) transcription factor, previously characterized as a component of the FR-HIR pathway...
  10. Liu Y, Liu Q, Yan Q, Shi L, Fang Y. Nucleolus-tethering system (NoTS) reveals that assembly of photobodies follows a self-organization model. Mol Biol Cell. 2014;25:1366-73 pubmed publisher
  11. Hornitschek P, Lorrain S, Zoete V, Michielin O, Fankhauser C. Inhibition of the shade avoidance response by formation of non-DNA binding bHLH heterodimers. EMBO J. 2009;28:3893-902 pubmed publisher
    ..and 5 (PIF4 and PIF5) are stabilized in the shade and are required for a full SAS, whereas the related bHLH factor HFR1 (long hypocotyl in FR light) is transcriptionally induced by shade and inhibits this response...
  12. Zhao R, Sun H, Mei C, Wang X, Yan L, Liu R, et al. The Arabidopsis Ca(2+) -dependent protein kinase CPK12 negatively regulates abscisic acid signaling in seed germination and post-germination growth. New Phytol. 2011;192:61-73 pubmed publisher