BACKGROUND: Epigenetic modifications dictate major biological processes, such as control of gene activity during development and genome stability under stress. DNA methylation is a primary epigenetic mechanism mediated by a family of methyltransferase enzymes. Maintenance function of DNA methylation is well conserved among plants and animals, based on the structural similarity of their methylation proteins. In contrast to plants, however, mammals do not tolerate loss of methylation, making it difficult to study. The model plant Arabidopsis offers a powerful test system for plant and mammalian methylation, because its methylation mutants are viable and fertile, and methylation patterns are not erased via developmental demethylation/remethylation cycles. Plants experience more extreme environment than mammals, and the evolution of plant methyltransferases may have favoured improved stress adaptation, while in mammals, it may lead to more stable establishment and resetting phases during development.OBJECTIVES: 1) To exploit Arabidopsis as an experimental system for mammalian epigenetic studies; 2) to elucidate the evolution of epigenetic diversity by defining differences and conserved function of plant and mammalian methylation regulators; 3) to assess how methylation affects plant stress adaptation.METHODOLOGY: Re-methylation efficiency in methylation mutants and prevention of methylation loss in plants by mammalian transgenes will be tested by bisulphite sequencing and chromatin immunoprecipitation. Hybrid constructs between the plant and animal proteins will be used. Methylation mutants will be exposed to abiotic variables to compare their stress adaptability. EXPECTED RESULTS: To develop Arabidopsis as a model system for mammals, which may improve application of epigenetics in agriculture and medicine; to further understanding of epigenetic phenomena in plants and mammals, the evolution of methylation systems and their role in adapting to environmental change.