Characterization of a set of phytochrome-interacting factor-like bHLH proteins in Oryza sativa

Biosci Biotechnol Biochem. 2007 May;71(5):1183-91. doi: 10.1271/bbb.60643. Epub 2007 May 7.


The model dicotyledon Arabidopsis thaliana has a characteristic small sub-family of phytochrome-interacting bHLH (basic Helix-Loop-Helix) factors, which are collectively designated the PIL (or PIF) (PHYTOCHROME INTERACTING FACTOR-LIKE) family proteins. In this study, we identified and characterized a set of highly homologous members (designated OsPIL11 to OsPIL16) in the model monocotyledon rice (Oryza sativa). Some of them (OsPIL11, OsPIL12, and OsPIL13) showed the ability to interact with the putative OsPRR1 (PSEUDO-RESPONSE REGULATOR 1) clock component, as far as the results of yeast two-hybrid assays were concerned. It was found that the expression of OsPIL13 is under the control of circadian rhythms (clock), while the expression of OsPIL15 is negatively regulated by light upon the onset to light exposure of etiolated seedlings. When the rice genes (OsPIL11 to OsPIL15) were over-expressed in A. thaliana, the resulting transgenic seedlings displayed anomalous morphologies with very long hypocotyls during early photomorphogenesis. These results suggest the view that the identified OsPILs are functional counterparts (or orthologs) of AtPILs, which are known to play important roles in red light-mediated (phyA and/or phyB-dependent) signal transduction pathways at immediate positions downstream of the photoreceptor in A. thaliana.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Motifs
  • Amino Acid Sequence
  • Basic Helix-Loop-Helix Transcription Factors / metabolism*
  • Basic Helix-Loop-Helix Transcription Factors / radiation effects
  • Circadian Rhythm / radiation effects
  • Conserved Sequence
  • DNA, Complementary
  • DNA, Plant / genetics
  • Gene Expression Regulation, Plant / radiation effects
  • Genes, Plant
  • Light
  • Molecular Sequence Data
  • Oryza / chemistry*
  • Oryza / genetics
  • Phylogeny
  • Phytochrome / metabolism*
  • Phytochrome / radiation effects
  • Protein Structure, Tertiary
  • Sequence Analysis, Protein
  • Sequence Homology, Amino Acid
  • Signal Transduction / radiation effects
  • Transcription, Genetic / radiation effects
  • Two-Hybrid System Techniques


  • Basic Helix-Loop-Helix Transcription Factors
  • DNA, Complementary
  • DNA, Plant
  • Phytochrome