title: Opposing effects of reduced DNA methylation on flowering time in Arabidopsis thaliana.
abstract: Demethylation of DNA promotes flowering in plants from the vernalization-responsive ecotype C24 of Arabidopsis thaliana (L.) Heynh., but delays flowering in the ecotype Landsberg erecta which is not responsive to vernalization. To investigate these contrasting effects of low methylation we have monitored flowering times and expression of two repressors of flowering, FLC and FWA, in low-methylation plants from three late-flowering mutants in the ecotype Landsberg erecta. Demethylation of DNA decreased FLC expression in the vernalization-responsive mutants, but was not associated with a promotion of flowering; rather, in some lines, demethylation delayed flowering. The opposing effects of demethylation could be explained by its differential effect on the expression of two repressors of flowering. FLC was down-regulated in plants with low methylation, promoting flowering, while FWA was activated in response to demethylation, which probably delays the transition to flowering. Expression of the FWA gene did not delay flowering in plants of ecotype C24; our data suggest that the FWA protein of C24 may be non-functional.
authors.affiliation: Division of Biochemistry and Molecular Biology, Australian National University, Canberra, ACT 0200, Australia.
authors.forename: Ruth K
authors.initials: RK
authors.lastname: Genger
authors.forename: W James
authors.initials: WJ
authors.lastname: Peacock
authors.forename: Elizabeth S
authors.initials: ES
authors.lastname: Dennis
authors.forename: E Jean
authors.initials: EJ
authors.lastname: Finnegan
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D019175:DNA Methylation; D035264:Flowers / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D026161:MADS Domain Proteins / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D013997:Time Factors; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; C418902:At5g10140 protein, Arabidopsis; C416366:FWA protein, Arabidopsis; D018398:Homeodomain Proteins; D026161:MADS Domain Proteins; D010940:Plant Proteins; D014157:Transcription Factors