Epigenetic Regulations During Plant-Microbe Interactions

Epigenetic modification is a mechanism of gene expression resulting from changes in chromatin structure and functions without alteration of the DNA sequence. In eukaryotes (animals, plants, and fungi), DNA is compact and wrapped around histone proteins, epigenetic modification has been achieved through DNA cytosine methylation and histone changes. For example, post-translational changes of histone tails, together with methylation-demethylation and acetylation–deacetylation, influence chromatin shape and may spark off and deactivate gene expression. However, bacteria do not possess histones, DNA adenine and cytosine methylation is the foremost epigenetic change that affects the transcription of genes and that still protects DNA from cleavage by means of bacterial restriction-change systems (which assault overseas DNA) (de Bruijn and Verhoeven 2018). Cytosine methylation in post-replicative nuclear DNA is a conserved form of epigenetic modification seen in both bacteria and eukaryotes that regulate gene expression and suppress transposon activities (Zhong et al. 2014). DNA methylation predominantly occurs in the CG context in mammals (Lister et al. 2009) while plant DNA is methylated at three different sequence contexts: CG, CHG and CHH (where, H = A, T or C) (Law and Jacobsen 2010).