Epigenetic variation creates potential for evolution of plant phenotypic plasticity

TLDR

Heritable phenotypic variation in plants can arise from DNA sequence changes or epigenetic differences, yet the extent and evolutionary importance of such epigenetic effects remain largely unexplored. We performed a glasshouse experiment with numerous epigenetic recombinant inbred lines of Arabidopsis thaliana, which are nearly isogenic but differ in DNA methylation, to assess their responses to drought and elevated nutrient conditions. The epi RILs displayed significant heritable differences in key ecological traits and their plasticities, with selection gradients indicating that epigenetic variation can influence fitness, supporting the possibility of rapid evolution driven solely by DNA methylation changes.

Abstract

Summary Heritable variation in plant phenotypes, and thus potential for evolutionary change, can in principle not only be caused by variation in DNA sequence, but also by underlying epigenetic variation. However, the potential scope of such phenotypic effects and their evolutionary significance are largely unexplored. Here, we conducted a glasshouse experiment in which we tested the response of a large number of epigenetic recombinant inbred lines (epi RIL s) of Arabidopsis thaliana – lines that are nearly isogenic but highly variable at the level of DNA methylation – to drought and increased nutrient conditions. We found significant heritable variation among epi RIL s both in the means of several ecologically important plant traits and in their plasticities to drought and nutrients. Significant selection gradients, that is, fitness correlations, of several mean traits and plasticities suggest that selection could act on this epigenetically based phenotypic variation. Our study provides evidence that variation in DNA methylation can cause substantial heritable variation of ecologically important plant traits, including root allocation, drought tolerance and nutrient plasticity, and that rapid evolution based on epigenetic variation alone should thus be possible.