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Control of FWA gene silencing in Arabidopsis thaliana by SINE‐related direct repeats
Author(s) -
Kinoshita Yuki,
Saze Hidetoshi,
Kinoshita Tetsu,
Miura Asuka,
Soppe Wim J.J.,
Koornneef Maarten,
Kakutani Tetsuji
Publication year - 2007
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/j.1365-313x.2006.02936.x
Subject(s) - biology , dna methylation , genetics , epigenetics , epigenetics of physical exercise , rna directed dna methylation , genomic imprinting , methylation , gene , gene expression , microbiology and biotechnology
Summary A unique feature of late‐flowering fwa epigenetic mutations is that the phenotype is caused by ectopic expression of the homeobox gene FWA . During normal development the FWA gene is expressed specifically in the endosperm in an imprinted manner. Ectopic FWA expression and disruption of imprinting can be induced in mutants of a CG methyltransferase MET1 ( methyltransferase 1 ) or a chromatin‐remodeling gene DDM1 ( decrease in DNA methylation 1 ), suggesting that the proper FWA expression depends on cytosine methylation. However, critical methylated residues controlling FWA silencing are not pinpointed. Nor is it understood how the FWA gene is initially methylated and silenced in wild‐type plants. Here we mapped sequences critical for FWA silencing by application of RdDM (RNA‐directed DNA methylation) to a ddm1 ‐induced stable fwa epiallele. Transcription of double‐stranded RNA corresponding to the tandem direct repeats around the FWA transcription start site induced de novo DNA methylation, transcriptional suppression and phenotypic reversion. The induced changes were heritable even without the transgene, which correlates with inheritance of CG methylation in the direct repeats. The newly silenced FWA allele was transcribed in an endosperm‐specific and imprinted manner, as is the case for the wild‐type FWA gene. The results indicate that methylation of the direct repeats, which presumably originated from a short interspersed nuclear element (SINE), is sufficient to induce proper epigenetic control of the FWA gene.