Experimental treatment with a hypomethylating agent alters lifehistory traits and fitness in brassica rapa

Abstract

Epigenetic modifications to DNA can be inherited and may play a key role in evolution, with epigenetic influences on life history traits such as the timing of germination and flowering thought to be particularly important in plants. However, few studies have examined the effects of epigenetic modifications through experimental alteration of the methylome under differential growth conditions. In this study, we chemically induced global DNA hypomethylation using 5-azacytidine in three Brassica rapa plant populations differing in life history characteristics and under differing photoperiod treatments. We found that our 5- azacytidine treatment affected the timing of germination and that this effect differed across populations, with the treatment delaying germination in B. rapa Fast Plants, which have been artificially selected for rapid cycling, but accelerating germination in biennials. Rapid cycling B. rapa plants also were smaller and had lower reproductive fitness under the experimental demethylation treatment. There was no main effect of demethylation or photoperiod on flowering time, but the interaction was marginally significant, indicating that demethylation effects on flowering time depend on photoperiod. These results demonstrate that epigenetic modifications can influence phenotypic traits in ways that are dependent on genetic identity, life history, and light availability.