Exposure to environmental stress induces a transient epigenetic memory response in plants. Wibowo_et_al_2015

Environmental fluctuations occur constantly to varying extents yet rarely cause detrimental effects to the survival of organisms. Most organisms adapt slowly to novel environments by selecting genetic variants; it has been suggested, however, that induced epigenetic changes could accelerate this process especially in non-motile organisms such as plants. Here we report the identification of epigenetically labile regions of the Arabidopsis genome that are targeted by de novo methylation at non-CG sites and demethylation in response to hyperosmotic stress. These epigenetic changes are associated with transient adaptive phenotypic stress responses in the progeny and subsequent generations. The effects, however, are not transmitted equally through male and female sexual lineages due to the active epigenetic reprogramming operating in male gametes. Furthermore, contrary to current views, this ‘stress memory’ is gradually lost in subsequent generations once normal conditions resume, i.e. in the absence of stress. Further, we found that sequences targeted by DNA methylation were associated primarily with the expression of key stress-response regulators and antisense lncRNAs. Our data thus collectively indicate that plants have developed a highly dynamic ‘short-term memory’ stress response to perceive and respond to environmental stimuli via directing transient epigenetic changes to discrete loci, enabling offspring with mechanisms to cope with fluctuations in the environment.