DNA methylation in the form of 5-Methylcytosine (5mC) is a major epigenetic mark involved in gene expression and plays an important role in plant regulation and development. DNA methylation in plants commonly occurs at cytosine bases in all sequence contexts, the symmetric CG and CHG contexts (where H indicates A, T or C) and the asymmetric CHH contexts. DNA hypomethylation can produce severe phenotypic assignment as noted in the progeny of ddm1 Arabidopsis mutants.