DNA Methylation Profile of and Genes in Flax Shows Specificity Towards Strains Differing in Pathogenicity.

Most losses in flax ( L.) crops are caused by fungal infections. The new epigenetic approach to improve plant resistance requires broadening the knowledge about the influence of pathogenic and non-pathogenic strains on changes in the profile of DNA methylation. Two contrasting effects on the levels of methylation in flax have been detected for both types of strain infection: Genome-wide hypermethylation and hypomethylation of resistance-related genes ( and ). Despite the differences in methylation profile, the expression of these genes increased. Plants pretreated with the non-pathogenic strain memorize the hypomethylation pattern and then react more efficiently upon pathogen infection. The peak of demethylation correlates with the alteration in gene expression induced by the non-pathogenic strain. In the case of pathogen infection, the expression peak lags behind the gene demethylation. Dynamic changes in tetramer methylation induced by both pathogenic and non-pathogenic strains are dependent on the ratio between the level of methyltransferase and demethylase gene expression. Infection with both strains suppressed methyltransferase expression and increased the demethylase () transcript level. The obtained results provide important new information about changes in methylation profile and thus expression regulation of pathogenesis-related genes in the flax plant response to stressors.