Transgenerational Epigenetic Instability Is a Source of Novel Methylation Variants

TLDR

Epigenetic information can be stored and stably inherited as cytosine DNA methylation, yet the spontaneous rates of methylation gain or loss remain unknown. The study tracked spontaneous methylation variation in Arabidopsis thaliana propagated by single‑seed descent for 30 generations. They identified 114,287 CG single‑methylation polymorphisms and 2,485 CG differentially methylated regions that diverge from the ancestor, showing that transgenerational epigenetic variation can create new allelic states that alter transcription and generate phenotypic diversity without genetic mutation.

Abstract

Epigenetic information, which may affect an organism's phenotype, can be stored and stably inherited in the form of cytosine DNA methylation. Changes in DNA methylation can produce meiotically stable epialleles that affect transcription and morphology, but the rates of spontaneous gain or loss of DNA methylation are unknown. We examined spontaneously occurring variation in DNA methylation in Arabidopsis thaliana plants propagated by single-seed descent for 30 generations. We identified 114,287 CG single methylation polymorphisms and 2485 CG differentially methylated regions (DMRs), both of which show patterns of divergence compared with the ancestral state. Thus, transgenerational epigenetic variation in DNA methylation may generate new allelic states that alter transcription, providing a mechanism for phenotypic diversity in the absence of genetic mutation.