Role of Methylation during geminivirus infection

Epigenetic marks are reversible molecular changes associated to DNA or histones, and are important regulators of gene expression and genome plasticity. In plants, the covalent binding of a methyl group to cytosine or to the lysine 9 residue of H3 histone is promoting transcriptional silencing. These silencing marks are normally associated to the suppression of selfish genetic mobile elements, because their activation might lead to their uncontrolled proliferation and to genome instability. Considering that DNA viruses replicate their genome in the host nucleus hijacking host cellular factors, similarly to endogenous genetic elements, it is not surprising that host plants have adopted epigenetic mechanisms as defense strategies also against this kind of pathogens. In this chapter, we will review the relevance of DNA and histone methylation in controlling the infection of geminiviruses, the most prevalent family of pathogenic DNA viruses in plants.