The MOM1 complex recruits the RdDM machinery via MORC6 to establishde novoDNA methylation

Abstract

MOM1 is an Arabidopsis factor previously shown to mediate transcriptional silencing independent of major DNA methylation changes. Here we found that MOM1 localizes with sites of RNA-directed DNA methylation (RdDM). Tethering MOM1 with artificial zinc finger to unmethylated FWA promoter led to establishment of DNA methylation and FWA silencing. This process was blocked by mutations in components of the Pol V arm of the RdDM machinery, as well as by mutation of MORC6. We found that at some endogenous RdDM sites, MOM1 is required to maintain DNA methylation and a closed chromatin state. In addition, efficient silencing of newly introduced FWA transgenes was impaired by mutation of MOM1 or mutation of genes encoding the MOM1 interacting PIAL1/2 proteins. In addition to RdDM sites, we identified a group of MOM1 peaks at active chromatin near genes that colocalized with MORC6. These findings demonstrate a multifaceted role of MOM1 in genome regulation.

Simultaneous Profiling of Chromatin Accessibility and DNA Methylation in Complete Plant Genomes Using Long-Read Sequencing

“…Interestingly, unlike CS9, which display the lowest accessibility and highest 5mC levels in the three sequence contexts, CS8 has high mCHH but reduced mCG and mCHG (Figure 2A), suggesting that the latter may be targets of the siRNA-directed DNA methylation pathway (RdDM). Simultaneous targeting of these loci by RdDM and PRC2 is consistent with recent studies demonstrating in vivo interaction of MORPHEUS’ MOLECULE1 (MOM1) and AIPP3 factors (29, 30), which are respectively involved in RdDM-mediated methylation and H3K27me3 recognition. In combination, these results provide evidence that CHH methylation, in combination with H3K27me3, might constitute a form of relaxed heterochromatin.…”

Atypical epigenetic and small RNA control of transposons in clonally reproducingSpirodela polyrhiza

“…S6-S16 ). For gene expression, we performed short-read transcriptome analysis in Spirodela and compared it to that of recently published Arabidopsis seedlings [74] ( Fig. 2 ).…”

“…NGS data generated for this study are accessible NCBI SRA under ID number PRJNA1095698, submission ID SUB14339214. Publicly available Arabidopsis seedling transcriptome from [74] is found under the accession number GSM6892968. Ready-to-use IGV genome browser tracks for all the NGS datasets generated here is available in the associated Zenodo dataset.…”

Emerging roles of plant transcriptional gene silencing under heat

“…Additional agents of TGS—but seemingly independent of DNA methylation maintenance—emerge through chromatin remodeling, where a classical pathway involves the gene MORPHEUS MOLECULE 1 ( MOM1 ) that controls suppressive chromatin in intermediate states (Yokthongwattana et al., 2010). Genes from the MICRORCHIDIA ( MORC ) family have also been associated in coordination with MOM1 , in modes dependent or independent of RdDM (Li et al., 2023; Xue et al., 2021).…”