GLS seminar by Rebecca Mosher – RNA directed DNA Methylation: a maternal influence during seed development
Speaker: Rebecca Mosher (Becky Mosher) University of Oxford, Oxford, UK
Date: Tuesday 25 November 2025
Time: 15:00 -16:00
Location UvA Science Park 904, Room C0.05
Host: Maike Stam
*followed by a meet up with the speaker for GLS master students, PhD candidates, and postdocs of the plant groups (hosted by Juliette Aubert)
24-nt small interfering (si)RNAs establish DNA methylation at thousands of genomic loci in a process called RNA-directed DNA Methylation (RdDM). RdDM is dispensable for growth and development in Arabidopsis, but is required for reproduction in many other plant species, particularly historically outbreeding species. In Brassica rapa, the embryo and endosperm abort if RdDM is disrupted in the maternal sporophyte, implying communication between maternal and filial tissues. During reproduction, 24-nt siRNAs are particularly abundant in maternal sporophytic tissue such as the seed coat, largely due to overwhelming expression from a small number of “siren” loci. Siren loci account for over 90% of siRNAs in ovules and early seeds, and many siRNAs are produced from gene fragments embedded in these loci. We recently demonstrated that these siRNAs trigger methylation at homologous protein-coding genes, and in some cases this trans-methylation impacts expression of the target gene. In the endosperm, siren siRNAs are maternally biased, suggesting that siRNAs might be transported to, and function in, filial tissues. Together, these observations suggest that maternally-derived siren siRNAs might methylate protein-coding genes in filial tissues to influence seed development.
Two papers linked to the seminar: