Traditionally, epigenetic variation is not thought to play a significant role in ecology and evolution because of its inherent instability. Recently, however, epigenetic variation has raised a lot of interest in this field because the high rates at which it arises might allow for rapid adaptation. It has been proposed that epigenetic variation could potentially contribute to mitigate the rapid changes occurring as a consequence of global climate change. However, for naturally occurring or induced epigenetic variation to be useful in the adaptation of natural populations or crop plants to a changing environment, epigenetic variation has to be heritable and sufficiently stable to respond to selection.

We are addressing questions related to the stability, heritability, and selectionability of epigenetic variation in the model plant Arabidopsis thaliana, where we performed various selection experiments and assessed changes in the epigenome, focusing on DNA-methylation as a proxy for epigenetic variation. We assessed ancestral and selected populations by genome-wide bisulfite sequencing, transcriptome analyses, and genome resequencing. Our results suggest that purely epigenetic variation can indeed be selected and give rise to novel phenotypes that are stable for at least a few generations in the absence of selection. However, a response to selection depends on a sufficient level of standing epigenetic variation being present in the population, which appears to be rare.

I will report on our progress of studies addressing how the stability of epigenetic variation over generations is affected by genetic background. For instance, we follow the inheritance of epigenetic variation in hybrids or after back-crossing, typical of classical breeding schemes. We are also assessing epigenetic variation in natural populations to address whether it can play a role in adaptation in nature.

 

東京大学大学院理学系研究科・生物科学専攻・発生細胞生物学研究室

連絡先：東山哲也（24469）、土金勇樹（土松研究室）