Epigenome-wide association studies (EWAS) to analyze methylation patterns in the conifer species Norway spruce (Picea abies)

To study methylation patterns in the conifer species, targeted bisulfite sequencing (TBS) approach was applied in Norway spruce (Picea abies). The focus of this study is set on 20 samples from clonal individuals from three genotypes (IDs 4960703, 4259732, and 186370) that were grown at three locations in Germany namely Neuhaus, Goeppingen (with G extension), and Harsefeld (with H extension). Trees in Neuhaus were sampled at three heights (labeled with unique numbers or mitte (middle), oben (up), unten (below) extensions). The trees were accessed by the Northwest German Forest Research Institute (NWFVA) in the framework of the "fit for clim" project. The trees were planted in 1970 (IDs 4960703, and 186370) and 1973 (IDs 4259732) in these three locations that differ in their climatic conditions. We investigated the methylomes of these samples, identified differentially methylated positions (DMPs), and differentially methylated regions (DMRS), and used this data to test the EpiDiverse EWAS pipeline. EpiDiverse is a Marie Sklodowska-Curie Innovative Training Network (ITN) aimed at the study of epigenetic variation in wild plant species. Further, we included eight samples from an existing BioProject (PRJEB26494) that were previously published by Heer et al. 2018. TBS was successfully applied in Norway spruce and can be further upscaled or transferred to other conifer species to broaden our knowledge of methylation patterns in natural tree populations.