Testing the stability and adaptive potential of stress-induced epigenetic variation – MEMOSTRESS

Until recently, a key assumption in biology has been that DNA sequence mutations are the only source of heritable phenotypic variation and therefore that adaptation is impossible in the absence of DNA sequence variants. However, this view is being increasingly challenged by the observation that changes in chromatin states, which are pivotal for the control of genome activity in eukaryotes, can in some instances be induced by the environment and inherited across multiple sexual generations independently of any change in the genome sequence. This system of inheritance, called epigenetic, is best documented in plants and often involves differential DNA methylation of repeat sequences, notably transposable elements (TEs). However, there is still a lack of systematic studies that experimentally examine the stability and consequences of environmentally induced epigenetic changes and test their ecological or evolutionary relevance, which could be different from that of DNA sequence variants, notably by providing a more rapid and reversible route to adaptation. Here, we propose to address this issue through an ambitious interdisciplinary project that relies on a unique combination of resources and expertise. The main objectives are 1) to determine the extent and stability across multiple generations of stress-induced epiallelic variation in several natural accessions of the reference plant Arabidopsis using approaches based on Next Generation Sequencing (NGS); 2) to assess the phenotypic consequences and adaptive potential of stress-induced epigenetic variants (epimutations) using a state-of-the-art, high-throughput phenotyping platform; 3) to compare the results of 1) and 2) with those obtained using epigenetic recombinant inbred lines (epiRILs) that segregate numerous genetically-induced DNA methylation perturbations and 4) to develop selection equations and adaptive dynamics models of evolving systems with an epigenetic architecture.

Thanks to the integrative nature of this project, we can expect major insights into the extent and ecological relevance of environmentally-induced epigenetic variation. In turn, this new knowledge may pave the way for the development of novel approaches for predicting and/or increasing plant adaptability in response to the increasingly rapid global changes the world is experiencing.