Locus-Specific Reactivation of the MuDR Transposon.

When MuDR and Muk are both present in one plant, the MuDR elements become epigenetically silenced as a result of a long hairpin RNA molecule produced from Muk that acts in trans to initiate DNA methylation of MuDR elements. At most loci, once the MuDR has been silenced it remains so even after Muk segregates away (A). In contrast (B), when inserted within the Hemera (black bar) locus, MuDR was reactivated in progeny plants that did not inherit MuK.