DNA methylation inheritance across generations

Cytosine DNA methylation regulates the expression of eukaryotic genes and transposable elements. Methylation is copied by DNA methyltransferases after DNA replication, which results in faithful transmission of methylation patterns during cell division and, at least in flowering plants, across generations. Trans-generational inheritance is mediated by a small group of cells that includes gametes and their progenitors. However, methylation is usually analyzed in somatic tissues that do not contribute to the next generation, and the mechanisms of trans-generational inheritance are inferred from such studies. To gain a better understanding of how DNA methylation is inherited, we analyzed purified Arabidopsis thaliana sperm and vegetative cells – the cell types that comprise pollen – with mutations in the DRM, CMT2 and CMT3 methyltransferases. We isolated sperm and vegetative nuclei from pollen of Col-0, and cmt2, cmt3, drm1 drm2 (d1d2), and h1.1 h1.2 (h1) mutant Arabidopsis thaliana plants, respectively. DNA is extracted from the isolated nuclei and used for bisulfite-sequencing.