“…M ethylation of DNA encoding transposable elements (TE) is required to silence their expression and consequently prevent them from mobilizing and mutagenizing genomes (Kato et al, 2003;Law and Jacobsen, 2010). Complex mechanisms have evolved to balance the high degree of sensitivity needed to direct methylation and silencing of TEs with the precision required to prevent ectopic methylation of endogenous genes (Antunez-Sanchez et al, 2020;Ito et al, 2015;Papareddy et al, 2020;Saze and Kakutani, 2011;Williams et al, 2015;Zhang et al, 2020). However, little is known about the mechanisms of epigenome homeostasis during embryogenesis when organisms are particularly vulnerable to TE-induced mutagenesis, as well as the establishment of potentially deleterious epimutations that can persist through many cell divisions and even across generations (Henderson and Jacobsen, 2007;Mathieu et al, 2007;Probst et al, 2009;Saze et al, 2003;Scheid et al, 1998).…”