title: SUPPRESSOR OF FRI 4 encodes a nuclear-localized protein that is required for delayed flowering in winter-annual Arabidopsis.
abstract: The floral inhibitor FLOWERING LOCUS C (FLC) is a crucial regulator of flowering time in Arabidopsis, and is positively regulated by the FRIGIDA (FRI) gene in late-flowering winter-annual accessions. In rapid-cycling accessions, FLC expression is suppressed by the autonomous floral-promotion pathway (AP); thus AP mutants contain high levels of FLC and are late flowering. Previous work has shown that the upregulation of FLC in FRI- or AP-mutant backgrounds is correlated to an increase in histone H3 lysine 4 (H3K4) trimethylation at the FLC locus. This increase in trimethylation requires a PAF1-like complex and EARLY FLOWERING IN SHORT DAYS (EFS), a putative histone H3 methyltransferase. We have identified a putative zinc-finger-containing transcription factor, SUF4, that is required for the upregulation of FLC by FRI. suf4 mutations strongly suppress the late-flowering phenotype of FRI, but only weakly suppress AP mutants. As with mutants in efs or the PAF1-like complex, suf4 mutants show reduced H3K4 trimethylation at FLC. An interesting distinction between the phenotypes of suf4 mutants and mutants in efs or the PAF1-like complex is observed in the expression of genes that are adjacent to FLC or FLC-like genes. In efs and PAF1-like-complex mutants, the expression of FLC, FLC-like genes and adjacent genes is suppressed. In suf4 mutants, however, only FLC expression is suppressed. These data are consistent with a model in which SUF4 may act to specifically recruit EFS and the PAF1-like complex to the FLC locus.
authors.affiliation: Department of Biology, Indiana University, Bloomington, IN 47405, USA.
authors.forename: Sang Yeol
authors.initials: SY
authors.lastname: Kim
authors.forename: Scott D
authors.initials: SD
authors.lastname: Michaels
mesh_terms: D017398:Alternative Splicing; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism*; D001483:Base Sequence; D018744:DNA, Plant / Q000235:genetics; D035264:Flowers / Q000254:growth & development / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D006657:Histones / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics* / Q000378:metabolism*; D010641:Phenotype; D012621:Seasons; D017386:Sequence Homology, Amino Acid; D016335:Zinc Fingers / Q000235:genetics
chemical_list: D029681:Arabidopsis Proteins; D018744:DNA, Plant; C414613:FRI protein, Arabidopsis; D006657:Histones; D009687:Nuclear Proteins