DNA methylation mutants in elucidate individual roles of CG and non-CG methylation in genome regulation.

Cytosine (DNA) methylation in plants regulates the expression of genes and transposons. While methylation in plant genomes occurs at CG, CHG, and CHH sequence contexts, the comparative roles of the individual methylation contexts remain elusive. Here, we present as the second plant system, besides , with viable mutants with an essentially complete loss of methylation in the CG and non-CG contexts.

Publisher Correction: RdDM-independent de novo and heterochromatin DNA methylation by plant CMT and DNMT3 orthologs.

The original version of this Article contained an error in Fig. 5, in which the evolutionary origin of DRM2 was incorrectly placed prior to the divergence between gymnosperms and angiosperms . The correct evolutionary origin of DRM2 should be in angiosperms.

RdDM-independent de novo and heterochromatin DNA methylation by plant CMT and DNMT3 orthologs.

To properly regulate the genome, cytosine methylation is established by animal DNA methyltransferase 3 s (DNMT3s). While altered DNMT3 homologs, Domains rearranged methyltransferases (DRMs), have been shown to establish methylation via the RNA directed DNA methylation (RdDM) pathway, the role of true-plant DNMT3 orthologs remains elusive. Here, we profile de novo (RPS transgene) and genomic methylation in the basal plant, Physcomitrella patens, mutated in each of its PpDNMTs.

DNA METHYLTRANSFERASE 1 is involved in (m)CG and (m)CCG DNA methylation and is essential for sporophyte development in Physcomitrella patens.

DNA methylation has a crucial role in plant development regulating gene expression and silencing of transposable elements. Maintenance DNA methylation in plants occurs at symmetrical (m)CG and (m)CHG contexts ((m) = methylated) and is maintained by DNA METHYLTRANSFERASE 1 (MET1) and CHROMOMETHYLASE (CMT) DNA methyltransferase protein families, respectively. While angiosperm genomes encode for several members of MET1 and CMT families, the moss Physcomitrella patens, serving as a model for early divergent land plants, carries a single member of each family.

A single CMT methyltransferase homolog is involved in CHG DNA methylation and development of Physcomitrella patens.

C-5 DNA methylation is an essential mechanism controlling gene expression and developmental programs in a variety of organisms. Though the role of DNA methylation has been intensively studied in mammals and Arabidopsis, little is known about the evolution of this mechanism. The chromomethylase (CMT) methyltransferase family is unique to plants and was found to be involved in DNA methylation in Arabidopsis, maize and tobacco.