Epigenetic Variation and Inheritance

Washington University, Saint Louis MO

Investigators

Abstract

Genomes encode information in two ways, genetically and epigenetically. Genetic information is that contained in the nucleotide sequence of the genome, whereas epigenetic information is that contained elsewhere, typically in modifications to the nucleotides or to the chromatin. Epigenetic information in the form of differential DNA methylation and alternative chromatin packaging influences access to the underlying genetic information and thereby plays a central role in the modulation of gene expression. This project focuses on variation in epigenetic information and the extent to which this variation can affect inheritance from one generation to the next. The impetus for this project was the observation of the effects of altering cytosine methylation in Arabidopsis thaliana. In this plant, reduction in cytosine methylation leads to stable inherited variation in epigenetic information. This variation, in turn, generates abnormal phenotypes at the whole organism level. The project involves two major components. The first is the investigation of the molecular basis of the DNA hypomethylation-induced dwarfing defect, bal, caused by an epigenetic alteration that leads to elevated transcription of a pathogen resistance gene. The second objective is to determine the prevalence of epigenetic variation generated under more natural conditions (i.e. in the absence of mutations that destroy proper epigenetic modification). To establish a baseline for epigenetic variation in this model species, the investigator will study the occurrence of alternative epigenetic alleles among different Arabidopsis strains. Understanding the influence of modifications to nucleotides in genes and of the packaging of chromosomes is essential to understanding inheritance. This project will help the scientific community in this endeavour.