DNA methylation dynamics in response to stress : An insight into stress-induced and stably inherited DNA methylation variants in asexual and sexual plants

Abstract

The term Epigenetics was first used by the developmental biologist Conrad Waddington in 1940, who while studying the fruit fly Drosophila, discovered that exposing developing individuals to heat stress induced changes in wing structure, which was in turn inherited over several generations (Waddington, 1940). He integrated the term 'epigenesis' with 'genetics' to describe this complex interaction between the developmental environment and the genome he observed in Drosophila. Epigenetic literally means 'epi' (greek for 'on top of') genetics. Over the years, as our understanding of molecular mechanisms involved in gene expression improved, the definition of 'epigenetics' underwent numerous substantial changes. Within the scope of this thesis, I refer to epigenetics as heritable (mitotically and/or meiotically), stable molecular mechanisms that regulate genome activity without modifying the underlying DNA sequence (E. J. Richards, 2006).