Arabidopsis TERMINAL FLOWER 2 gene encodes a heterochromatin protein 1 homolog and represses both FLOWERING LOCUS T to regulate flowering time and several floral homeotic genes

Plant Cell Physiol. 2003 Jun;44(6):555-64. doi: 10.1093/pcp/pcg091.

Abstract

Floral transition should be strictly regulated because it is one of the most critical developmental processes in plants. Arabidopsis terminal flower 2 (tfl2) mutants show an early-flowering phenotype that is relatively insensitive to photoperiod, as well as several other pleiotropic phenotypes. We found that the early flowering of tfl2 is caused mainly by ectopic expression of the FLOWERING LOCUS T (FT) gene, a floral pathway integrator. Molecular cloning of TFL2 showed that it encodes a protein with homology to heterochromatin protein 1 (HP1) of animals and Swi6 of fission yeast. TFL2 protein localizes in subnuclear foci and expression of the TFL2 gene complemented yeast swi6(-) mutants. These results suggested that TFL2 might function as an HP1 in Arabidopsis: Gene expression analyses using DNA microarrays, however, did not show an increase in the expression of heterochromatin genes in tfl2 mutants but instead showed the upregulation of the floral homeotic genes APETALA3, PISTILLATA, AGAMOUS and SEPALLATA3. The pleiotropic phenotype of the tfl2 mutant could reflect the fact that TFL2 represses the expression of multiple genes. Our results demonstrate that despite its homology to HP1, TFL2 is involved in the repression of specific euchromatin genes and not heterochromatin genes in Arabidopsis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • AGAMOUS Protein, Arabidopsis / genetics
  • Arabidopsis / genetics*
  • Arabidopsis / growth & development*
  • Arabidopsis / metabolism
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / isolation & purification*
  • Chromobox Protein Homolog 5
  • Chromosomal Proteins, Non-Histone / genetics
  • Chromosomal Proteins, Non-Histone / isolation & purification*
  • DNA, Complementary / analysis
  • DNA, Complementary / genetics
  • Flowers / genetics*
  • Flowers / growth & development*
  • Flowers / metabolism
  • Gene Expression Regulation, Plant / genetics
  • Genes, Homeobox / genetics
  • Homeodomain Proteins / genetics
  • MADS Domain Proteins / genetics
  • Molecular Sequence Data
  • Mutation / genetics
  • Repressor Proteins / genetics*
  • Repressor Proteins / isolation & purification*
  • Repressor Proteins / metabolism
  • Saccharomyces cerevisiae Proteins / genetics
  • Saccharomyces cerevisiae Proteins / isolation & purification
  • Sequence Homology, Amino Acid
  • Sequence Homology, Nucleic Acid
  • Transcription Factors / genetics
  • Transcription Factors / isolation & purification

Substances

  • AGAMOUS Protein, Arabidopsis
  • APETALA 3 protein, Arabidopsis
  • Arabidopsis Proteins
  • Chromosomal Proteins, Non-Histone
  • DNA, Complementary
  • FT protein, Arabidopsis
  • Homeodomain Proteins
  • MADS Domain Proteins
  • PISTILLATA protein, Arabidopsis
  • Repressor Proteins
  • SEP3 protein, Arabidopsis
  • SWI6 protein, S cerevisiae
  • Saccharomyces cerevisiae Proteins
  • TFL2 protein, Arabidopsis
  • Transcription Factors
  • Chromobox Protein Homolog 5

Associated data

  • GENBANK/AB073490