A single amino acid change in the enhancer of zeste ortholog CURLY LEAF results in vernalization-independent, rapid flowering in Arabidopsis.
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.
Doyle
Mark R
MR
Department of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706-1544, USA.
Amasino
Richard M
RM
D000483:Alleles; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D019175:DNA Methylation; D035264:Flowers / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D006657:Histones / Q000378:metabolism; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism*; D026161:MADS Domain Proteins / Q000378:metabolism; D008969:Molecular Sequence Data; D018749:RNA, Plant / Q000378:metabolism; D016415:Sequence Alignment
D029681:Arabidopsis Proteins; C104597:CURLY LEAF protein, Arabidopsis; C418902:At5g10140 protein, Arabidopsis; C414613:FRI protein, Arabidopsis; D006657:Histones; D018398:Homeodomain Proteins; D026161:MADS Domain Proteins; D018749:RNA, Plant