Epigenetic regulation of telomere maintenance

As chromatin structures, telomeres undergo epigenetic regulation of their maintenance and function. In plants, these processes are likely of a higher complexity than in animals or yeasts, as exemplified by methylation of cytosines in plant telomeric DNA or reversible developmental regulation of plant telomerase. We highlight the dual role of telomeres from the epigenetic point of view: (i) as chromatin structures that are the subject of epigenetic regulation (e.g. DNA and histone modifications), and (ii) as chromosome domains acting themselves as epigenetic regulatory elements (e.g. in the telomere position effect). Possibly, some molecular tools (e.g. telomeric transcripts) are common to both these aspects of telomere epigenetics. We further discuss the justification for the classical textbook view of telomeres as heterochromatic structures.