Two components of the RNA-directed DNA methylation pathway associate with MORC6 and silence loci targeted by MORC6 in Arabidopsis

DNA methylation is a conserved epigenetic mark that is required for the silencing of transposons and introduced transgenes in eukaryotes. An RNA-directed DNA methylation pathway mediates de novo DNA methylation and thereby leads to transcriptional silencing in Arabidopsis. In this study, we find that two RNA-directed DNA methylation components interact with the microrchidia (MORC) protein MORC6 and lead to transcriptional silencing through a mechanism that is distinct from the RNA-directed DNA methylation pathway. MORC6 was previously thought to mediate transcriptional silencing through heterochromatin condensation. Our study suggests that the interaction of the RNA-directed DNA methylation components with MORC6 may mediate a link between DNA methylation and heterochromatin condensation. Overall design: RNA-seq: Compare the mRNA profiles of 2-week-old seedlings materials of mutants (morc6 and suvh2suvh9) to wild type Col-0 by Illumina suquencing. BS-seq: Whole genome methylation maps of 4 mutants (two replicates) were generated using BS-seq