Epigenetic transitions in plants not associated with changes in DNA or histone modification

Covalent modifications of DNA and histones correlate with chromatin compaction and with its transcriptional activity and contribute to mitotic and meiotic heritability of epigenetic traits. However, there are intriguing examples of the transition of epigenetic states in plants that appear to be uncoupled from the conventional mechanisms of chromatin-mediated regulation of transcription. Further study of the molecular mechanism and biological significance of such atypical epigenetic regulation may uncover novel aspects of epigenetic gene regulation and better define its role in plant development and environmental adaptation.