Epigenetic, transposon and small RNA determinants of hybrid dysfunctions.

Accumulating evidence suggests that hybrid genetic dysfunctions accrue not only because of sequence divergence of incompatible alleles but also result from a broad variety of mechanisms related to the maintenance of chromatin integrity. For example, it has been observed that hybridization in plants and mammals disrupts patterns of DNA methylation and imprinting. These epigenetic changes can be associated with transcriptional activation and mobilization of transposable elements in hybrids. It raises a question of how these alterations are matched by small regulatory RNAs, such as piwi-interacting RNAs, which play a potent role in both suppressing transposable elements and epigenetic control. The review offers a handful of glimpses into these complex dynamics.