XVI International Botanical Congess

Homology-dependent gene silencing (HDGS) is a type of epigenetic silencing involving interactions between homologous or complementary nucleic acid sequences. HDGS can occur transcriptionally or post-transcriptionally depending on the region of homology shared by interacting genes. Transcriptional gene silencing (TGS) can result when homologous regions comprise primarily promoter sequences. A variant of TGS is trans-silencing, in which a methylated silencing locus induces methylation and inactivation of an unlinked target locus with which it shares DNA sequence identity in promoter regions. Experiments aiming to identify promoter sequence-specific methylation signals originating at silencing loci and directing de novo methylation of homologous promoters at target loci will be discussed.