A single amino acid change in the enhancer of zeste ortholog CURLY LEAF results in vernalization-independent, rapid flowering in Arabidopsis

Plant Physiol. 2009 Nov;151(3):1688-97. doi: 10.1104/pp.109.145581. Epub 2009 Sep 15.

Abstract

Many strains of Arabidopsis (Arabidopsis thaliana) require exposure to prolonged cold for rapid flowering, a process known as vernalization. Vernalization in Arabidopsis results in the suppression of FLOWERING LOCUS C (FLC), a repressor of flowering. In a screen for mutants that no longer require vernalization for rapid flowering, we identified a dominant allele of the Enhancer of Zeste E(z) ortholog CURLY LEAF (CLF), clf-59. CLF is a Polycomb Group gene, and the clf-59 mutant protein contains a proline-to-serine transition in a cysteine-rich region that precedes the SET domain. Mutant plants are early flowering and have reduced FLC expression, but, unlike clf loss-of-function mutants, clf-59 mutants do not display additional pleiotropic phenotypes. clf-59 mutants have elevated levels of trimethylation on lysine 27 of histone H3 (H3K27me3) at FLC. Thus, clf-59 appears to be a gain-of-function allele, and this allele represses FLC without some of the components required for vernalization-mediated repression. In the course of this work, we also identified a marked difference in H3K27me3 levels at FLC between plants that contain and those that lack the FRIGIDA (FRI) gene. Furthermore, FRI appears to affect CLF occupancy at FLC; thus, our work provides insight into the molecular role that FRI plays in delaying the onset of flowering.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Alleles
  • Amino Acid Sequence
  • Amino Acid Substitution*
  • Arabidopsis / genetics*
  • Arabidopsis / metabolism
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism*
  • DNA Methylation
  • Flowers / genetics
  • Flowers / growth & development*
  • Flowers / metabolism
  • Gene Expression Regulation, Plant
  • Genes, Plant
  • Histones / metabolism
  • Homeodomain Proteins / genetics
  • Homeodomain Proteins / metabolism*
  • MADS Domain Proteins / metabolism
  • Molecular Sequence Data
  • RNA, Plant / metabolism
  • Sequence Alignment

Substances

  • Arabidopsis Proteins
  • CURLY LEAF protein, Arabidopsis
  • FLF protein, Arabidopsis
  • FRI protein, Arabidopsis
  • Histones
  • Homeodomain Proteins
  • MADS Domain Proteins
  • RNA, Plant