title: Rapid Evolution of Genomic Imprinting in Two Species of the Brassicaceae.
abstract: Genomic imprinting is an epigenetic phenomenon occurring in mammals and flowering plants that causes genes to adopt a parent-of-origin-specific mode of expression. While the imprinting status of genes is well conserved in mammals, clear estimates for the degree of conservation were lacking in plants. We therefore analyzed the genome-wide imprinting status of Capsella rubella, which shared a common recent ancestor with Arabidopsis thaliana ∼10 to 14 million years ago. However, only ∼14% of maternally expressed genes (MEGs) and ∼29% of paternally expressed genes (PEGs) in C. rubella were commonly imprinted in both species, revealing that genomic imprinting is a rapidly evolving phenomenon in plants. Nevertheless, conserved PEGs exhibited signs of selection, suggesting that a subset of imprinted genes play an important functional role and are therefore maintained in plants. Like in Arabidopsis, PEGs in C. rubella are frequently associated with the presence of transposable elements that preferentially belong to helitron and MuDR families. Our data further reveal that MEGs and PEGs differ in their targeting by 24-nucleotide small RNAs and asymmetric DNA methylation, suggesting different mechanisms establishing DNA methylation at MEGs and PEGs.
authors.affiliation: Department of Plant Biology, Uppsala BioCenter, Swedish University of Agricultural Sciences and Linnean Center for Plant Biology, 750 07 Uppsala, Sweden.
authors.forename: Marcelinus R
authors.initials: MR
authors.lastname: Hatorangan
authors.affiliation: Department of Ecology, Environment, and Plant Sciences, Science for Life Laboratory, Stockholm University, 114 18 Stockholm, Sweden.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Laenen
authors.affiliation: Department of Ecology, Environment, and Plant Sciences, Science for Life Laboratory, Stockholm University, 114 18 Stockholm, Sweden Department of Ecology and Genetics, Evolutionary Biology Centre, Uppsala University, 75236 Uppsala, Sweden.
authors.forename: Kim A
authors.initials: KA
authors.lastname: Steige
authors.affiliation: Department of Ecology, Environment, and Plant Sciences, Science for Life Laboratory, Stockholm University, 114 18 Stockholm, Sweden.
authors.forename: Tanja
authors.initials: T
authors.lastname: Slotte
authors.affiliation: Department of Plant Biology, Uppsala BioCenter, Swedish University of Agricultural Sciences and Linnean Center for Plant Biology, 750 07 Uppsala, Sweden claudia.kohler@slu.se.
authors.forename: Claudia
authors.identifier: 0000-0002-2619-4857
authors.initials: C
authors.lastname: Köhler
mesh_terms: D019607:Brassicaceae / Q000235:genetics* / Q000378:metabolism; D019175:DNA Methylation / Q000235:genetics / Q000502:physiology; D004251:DNA Transposable Elements / Q000235:genetics; D019143:Evolution, Molecular; D018506:Gene Expression Regulation, Plant / Q000235:genetics / Q000502:physiology; D018392:Genomic Imprinting / Q000235:genetics* / Q000502:physiology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D004251:DNA Transposable Elements; D010940:Plant Proteins