Paramutation: a trans-homolog interaction affecting heritable gene regulation

► RMR2 is a grass-specific protein required for 24 nt RNAs and for paramutation. ► Hybrid epigenomes represent paramutation-like trans-homolog interactions. ► Paramutation occurs in the absence of either RMR1-dependent or RMR2-dependent sRNA profile. ► Genes flanked by 24 nt targeted TEs are associated with reduced gene expression. ► RNA polymerase competitions appear to occur between genes and nearby transposons.