Experimental alteration of DNA methylation affects the phenotypic plasticity of ecologically relevant traits in Arabidopsis thaliana
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Heritable phenotypic variation in plants can be caused not only by underlying genetic differences, but also by variation in epigenetic modifications such as DNA methylation. However, we still know very little about how relevant such epigenetic variation is to the ecology and evolution of natural populations. We conducted a greenhouse experiment in which we treated a set of natural genotypes of Arabidopsis thaliana with the demethylating agent 5-azacytidine and examined the consequences of this treatment for plant traits and their phenotypic plasticity. Experimental demethylation strongly reduced the growth and fitness of plants and delayed their flowering, but the degree of this response varied significantly among genotypes. Differences in genotypes’ responses to demethylation were only weakly related to their genetic relatedness, which is consistent with the idea that natural epigenetic variation is independent of genetic variation. Demethylation also altered patterns of phenotypic plasticity, as well as the amount of phenotypic variation observed among plant individuals and genotype means. We have demonstrated that epigenetic variation can have a dramatic impact on ecologically important plant traits and their variability, as well as on the fitness of plants and their ecological interactions. Epigenetic variation may thus be an overlooked factor in the evolutionary ecology of plant populations.
KeywordsArabidopsis thaliana 5-azacytidine DNA methylation Epigenetics Natural variation Phenotypic plasticity
This work was partially supported by the NSF IOB-0450240, the Research Foundation of the State University of New York and New York SEA Grant. We are grateful to Justin Borevitz for providing the SNP data, and to Stefan Michalski for his help with the genetic distance matrices.
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