title: Evolutionary patterns of genic DNA methylation vary across land plants.
abstract: Little is known about patterns of genic DNA methylation across the plant kingdom or about the evolutionary processes that shape them. To characterize gene-body methylation (gbM) within exons, we have gathered single-base resolution methylome data that span the phylogenetic breadth of land plants. We find that a basal land plant, Marchantia polymorpha, lacks any evident signal of gbM within exons, but conifers have high levels of both CG and CHG (where H is A, C or T) methylation in expressed genes. To begin to understand the evolutionary forces that shape gbM, we first tested for correlations in methylation levels across orthologues(1,2). Genic CG methylation levels, but not CHG or CHH levels, are correlated across orthologues for species as distantly related as ferns and angiosperms. Hence, relative levels of CG methylation are a consistent property across genes, even for species that diverged ∼400 million years ago(3,4). In contrast, genic CHG methylation correlates with genome size, suggesting that the host epigenetic response to transposable elements also affects genes. Altogether, our data indicate that the evolutionary forces acting on DNA methylation vary substantially across species, genes and methylation contexts.
authors.affiliation: SOKENDAI (The Graduate University for Advanced Studies), Hayama, Kanagawa 240-0193, Japan.
authors.forename: Shohei
authors.initials: S
authors.lastname: Takuno
authors.affiliation: State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing, China.|Department of Ecology and Evolutionary Biology, University of California, 321 Steinhaus Hall, Irvine, California 92697-2525, USA.
authors.forename: Jin-Hua
authors.initials: JH
authors.lastname: Ran
authors.affiliation: Department of Ecology and Evolutionary Biology, University of California, 321 Steinhaus Hall, Irvine, California 92697-2525, USA.
authors.forename: Brandon S
authors.initials: BS
authors.lastname: Gaut
mesh_terms: D005075:Biological Evolution; D019175:DNA Methylation; D004251:DNA Transposable Elements / Q000235:genetics; D019669:Embryophyta / Q000235:genetics*; D044127:Epigenesis, Genetic; D018745:Genome, Plant / Q000235:genetics*; D010802:Phylogeny
chemical_list: D004251:DNA Transposable Elements