The late flowering phenotype of fwa mutants is caused by gain-of-function epigenetic alleles of a homeodomain gene.
The transition to flowering in Arabidopsis thaliana is delayed in fwa mutant plants. FWA was identified by loss-of-function mutations in normally flowering revertants of the fwa mutant, and it encodes a homeodomain-containing transcription factor. The DNA sequence of wild-type and fwa mutant alleles was identical in the genomic region of FWA. Furthermore, the FWA gene is ectopically expressed in fwa mutants and silenced in mature wild-type plants. This silencing is associated with extensive methylation of two direct repeats in the 5' region of the gene. The late flowering phenotype, ectopic FWA expression, and hypomethylation of the repeats were also induced in the ddm1 hypomethylated background. Mechanisms for establishment and maintenance of the epigenetic mark on FWA are discussed.
Soppe
W J
WJ
Laboratory of Genetics, Wageningen University, The Netherlands.
Jacobsen
S E
SE
Alonso-Blanco
C
C
Jackson
J P
JP
Kakutani
T
T
Koornneef
M
M
Peeters
A J
AJ
D000483:Alleles; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development / Q000502:physiology; D029681:Arabidopsis Proteins; D001483:Base Sequence; D018244:Chromosomes, Artificial, Yeast; D019175:DNA Methylation; D018744:DNA, Plant / Q000737:chemistry / Q000235:genetics*; D020868:Gene Silencing; D005801:Genes, Homeobox; D017343:Genes, Plant; D018398:Homeodomain Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D016296:Mutagenesis; D010940:Plant Proteins; D018547:Plant Stems / Q000502:physiology; D012333:RNA, Messenger / Q000032:analysis; D012091:Repetitive Sequences, Nucleic Acid; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016415:Sequence Alignment; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D014158:Transcription, Genetic; D014170:Transformation, Genetic
D029681:Arabidopsis Proteins; D018744:DNA, Plant; C416366:FWA protein, Arabidopsis; D018398:Homeodomain Proteins; D010940:Plant Proteins; D012333:RNA, Messenger; D014157:Transcription Factors