Send to

Choose Destination
Proc Natl Acad Sci U S A. 2015 Jan 20;112(3):917-22. doi: 10.1073/pnas.1413053112. Epub 2015 Jan 5.

Epigenetic transitions leading to heritable, RNA-mediated de novo silencing in Arabidopsis thaliana.

Author information

Department of Plant Sciences, University of Cambridge, Cambridge CB2 3EA, United Kingdom.
Department of Plant Sciences, University of Cambridge, Cambridge CB2 3EA, United Kingdom


In plants, RNA-directed DNA methylation (RdDM), a mechanism where epigenetic modifiers are guided to target loci by small RNAs, plays a major role in silencing of transposable elements (TEs) to maintain genome integrity. So far, two RdDM pathways have been identified: RNA Polymerase IV (PolIV)-RdDM and RNA-dependent RNA Polymerase 6 (RDR6)-RdDM. PolIV-RdDM involves a self-reinforcing feedback mechanism that maintains TE silencing, but cannot explain how epigenetic silencing is first initiated. A function of RDR6-RdDM is to reestablish epigenetic silencing of active TEs, but it is unknown if this pathway can induce DNA methylation at naïve, non-TE loci. To investigate de novo establishment of RdDM, we have used virus-induced gene silencing (VIGS) of an active flowering Wageningen epiallele. Using genetic mutants we show that unlike PolIV-RdDM, but like RDR6-RdDM, establishment of VIGS-mediated RdDM requires PolV and DRM2 but not Dicer like-3 and other PolIV pathway components. DNA methylation in VIGS is likely initiated by a process guided by virus-derived small (s) RNAs that are 21/22-nt in length and reinforced or maintained by 24-nt sRNAs. We demonstrate that VIGS-RdDM as a tool for gene silencing can be enhanced by use of mutant plants with increased production of 24-nt sRNAs to reinforce the level of RdDM.


Arabidopsis thaliana; RNA-directed DNA methylation; epigenetics; virus-induced gene silencing

[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for HighWire Icon for PubMed Central
Loading ...
Support Center