Epigenetics and the improvement of crop plants

Epigenetics is a term that refers to the changes in gene expression that are heritable and induced by DNA methylation, histones post-translational modifications, or sncRNA, not resulting from the DNA sequence rearrangements. Epigenetic modifications influence gene expression, and thus, the plasticity of plants' development and phenotype in response to external and internal factors. Until recently, the only known epigenetic modification of the DNA in eukaryotic organisms was 5-methylcytosine. The growing interest in epigenetics and the development of sensitive detection methods enabled the discovery of other modifications of the DNA nitrogenous bases, i.e., 4-methylcytosine and 6-methyladenine. However, whilst research on the 5mC distribution and role in eukaryotic organisms is widespread, analyses regarding 6mA are scarced. Nevertheless, there are indications of a potential epigenetic role of 6-methyladenine in eukaryotic genomes. Understanding epigenetic mechanisms, which are triggered in response to environmental changes, is crucial for agriculture. This review shows epigenetic mechanisms, with particular emphasis on adenine methylation in plants, as well as the role of epigenetic variation in epibreeding, affecting the improvement of agronomic traits.