Dynamic of DNA methylation during Arabidopsis reproduction

Cytosine methylation is a key epigenetic mark in many organisms, important for both transcriptional control and genome integrity. While relatively stable during somatic growth, DNA methylation is reprogrammed genome-wide during mammalian reproduction. Reprogramming is essential for zygotic totipotency, and to prevent transgenerational inheritance of epimutations. The extent of DNA methylation reprogramming in plants however remains unclear. Here, we developed sensors reporting with single-cell resolution CG and non-CG methylation in Arabidopsis. Live imaging during reproduction revealed distinct and sex-specific dynamics for both contexts. We found that CHH methylation in the egg cell depends on DRM2 and Pol V, two main actors of RNA-directed DNA methylation, but does not depend on Pol IV. Our sensors provide insight into global DNA methylation dynamics at the single cell level with high temporal resolution, and offer a powerful tool to track CG and non-CG methylation both during development and in response to environmental cues in all organisms with methylated DNA. Overall design: ChIP-seq experiments conducted using transgenic lines expressing either CG or non-CG binding proteins. mCG in WT (Col(O)), mCHH and drm1-drm2-cmt2-cmt3, plus inputs.