RNA-directed DNA methylation


RNA-directed DNA methylation is an epigenetic process first discovered in plants. During RdDM, double-stranded RNAs are processed to 21-24 nucleotide small interfering RNAs and guide methylation of homologous DNA loci. In plants dsRNAs may be generated from four sources:
Besides RNA molecules, a plethora of proteins are involved in the establishment of RdDM, like Argonautes, DNA methyltransferases, chromatin remodelling complexes. and the plant-specific Polymerase IV and Polymerase V. All these act in concert to add a methyl-group at the 5' position of cytosines. In contrast to animals, cytosines at all sequence context may get de novo methylated in plants.