Epigenetic regulation of seed development in flowering plants

The Fischer lab is interested in the epigenetic regulation of seed development in angiosperms, specifically Arabidopsis thaliana and Oryza sativa (rice).  Our main focus is investigation of the role of DNA methylation in the sexual reproduction of A. thaliana, specifically the process of DNA demethylation.  DNA demethylation is required for normal seed development, and is carried out by the DNA glycosylase DEMETER (DME;  the goddess of harvest).  In the female gametophyte, DME is expressed specifically in the central cell, and in the male gametophyte, it is expressed in the vegetative cell.

DNA demethylation, gene imprinting and transposon silencing

Gene imprinting is the expression of certain genes depending on their parent-of-origin, essential for normal development in both flowering plants and placental mammals. In plants, imprinting is mostly confined to the endosperm of the developing seed. DNA demethylation of specific loci in the female gametophyte is central to the control of this epigenetically regulated process. As such, DNA demethylation is essential during plant development due to its role in the regulation of gene imprinting. Our recent data, together with our collaborators in Daniel Zilberman’s lab, support this, but also reveal a more basal function for this process. DNA demethylation by DME seems to primarily regulate the activity of transposable elements, in order to protect the genomic integrity of progeny. The monoallelic silencing of genes whose expression is controlled by TEs, if conferring a selection advantage, may have led to the evolution of imprinted loci in flowering plant endosperm.