Control of FWA gene silencing in Arabidopsis thaliana by SINE-related direct repeats
Article first published online: 27 NOV 2006
The Plant Journal
Volume 49, Issue 1, pages 38–45, January 2007
How to Cite
Kinoshita, Y., Saze, H., Kinoshita, T., Miura, A., Soppe, W. J.J., Koornneef, M. and Kakutani, T. (2007), Control of FWA gene silencing in Arabidopsis thaliana by SINE-related direct repeats. The Plant Journal, 49: 38–45. doi: 10.1111/j.1365-313X.2006.02936.x
- Issue published online: 27 NOV 2006
- Article first published online: 27 NOV 2006
- Received 3 August 2006; accepted 24 August 2006.
- DNA methylation;
- RNA-directed DNA methylation
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.