Epigenetic variation, inheritance, and selection in plant populations.

Plant populations show phenotypic diversity, which may be caused by genetic and epigenetic variation. It has recently been shown that new epigenetic variants are generated at a higher rate than genetic variants and several studies have shown that epigenetic variation can be influenced by the environment. Although the heritability of environmentally induced epigenetic traits has gained increasing interest in past years, it is still not clear whether and to what extent induced epigenetic changes have a role in ecology and evolution. Some reports on model and nonmodel species support the possibility of adaptive epigenetic alleles, indicating that epigenetic variants are subject to natural selection. However, most of these studies rely solely on phenotypic data and no information is available about the underlying mechanisms. Thus, the role of inherited epigenetic variation for plant adaptation is unclear and further investigations are required to gain insights into the significance of epigenetic variation for ecological and evolutionary processes. Here, we review mechanisms of epigenetic regulation, epigenetic responses to environmental challenges, their inheritance, and their implication for adaptation and plant evolution.