Epigenetic Regulation in Plant Responses to the Environment
In this article, we review environmentally mediated epigenetic regulation in plants using two case histories. One of these, vernalization, mediates adaptation of plants to different environments and it exemplifies processes that are reset in each generation. The other, virus-induced silencing, involves transgenerationally inherited epigenetic modifications. Heritable epigenetic marks may result in heritable phenotypic variation, influencing fitness, and so be subject to natural selection. However, unlike genetic inheritance, the epigenetic modifications show instability and are influenced by the environment. These two case histories are then compared with other phenomena in plant biology that are likely to represent epigenetic regulation in response to the environment. Outline 1 Epigenetic regulation as environmental memory 2 Case history I-Vernalization 3 Case history II-Virus-induced gene silencing and epigenetics 4 Resetting versus transgenerational inheritance 5 Transient epigenetic regulation in response to stress 6 Transgenerational epigenetic regulation in response to stress 7 Epigenetic effects on genome structure 8 The heritable legacy of induced epigenetic changes