Epigenetics and plant genome evolution

Epigenetics was envisioned as a topic to inform evolutionary theory, but the interplay between epigenetics and evolution has received little attention. With the advent of high-throughput methods, it is now routine to measure the genome-wide distribution of epigenetic marks, and these genome-wide patterns are providing insights into evolutionary processes. For example, DNA methylation is associated with transposable element silencing but also with repression of the expression of nearby genes, perhaps caused by the spread of methylation into regulatory regions. This repressive effect, which is typically deleterious, is acted upon by purifying selection. These dynamics may also govern the outcome of hybridization and polyploid events by affecting homoeolog expression. Finally, genes are also often methylated, but the implications of genic methylation for plant gene and genome evolution are not yet characterized fully.