A comparison of transcriptome and epigenetic status between closely related species in the genus Arabidopsis.

Difference in the level of expression of genes is one of the factors contributing to plant phenotype. As well as being under genetic control, gene expression is regulated by epigenetic processes such as DNA methylation and histone modifications. We compared genome-wide gene expression between Arabidopsis thaliana and the related species Arabidopsis lyrata subsp. lyrata and Arabidopsis halleri subsp. gemmifera to understand which genes might contribute to species differences. Genes categorized into response to stress tended to show differential expression between species, suggesting that divergence of expression in these genes contributes to adaptation to environmental conditions following the divergence of species. Regions methylated in A. lyrata were identified from Methylated-DNA immunoprecipitation, and this DNA methylation profile together with transcriptome data revealed that gene body methylation was not associated with differential gene expression between A. thaliana and A. lyrata. The DNA methylation status of four putative imprinted genes of A. lyrata was examined and found to be conserved in vegetative tissues between A. thaliana and A. lyrata in FIS2, HDG3, and HDG9, but not in HDG8.