Abstract
Molecular analysis of the FWA gene revealed that all fwa mutants are gain-of-function epigenetic alleles of a homeodomain-containing putative transcription factor (Soppe W. et al. 2000). Ectopic expression of the FWA gene is associated with hypomethylation of the 5' direct repeats of the gene, and induces a late flowering phenotype. The heritable epigenetic late flowering trait is also found in the repeatedly selfed ddm1 (decrease in DNA methylation) mutant.
To understand epigenetic character of the FWA gene, we investigated parent-of-origin-dependent gene expression in the endosperm. The result indicated that the expression was observed only in the maternal allele, whereas the paternal allele was silenced. Furthermore, silencing of the paternal allele was not maintained in met1 (DNA methyltransferase1) or fwa-1 mutants. Based on these findings, we concluded that the FWA gene is a novel imprinted gene expressed in the endosperm.
