Mechanisms of Seed Development and Plant Speciation
Our lab has a general interest in genetic and epigenetic mechanisms governing seed development and plant speciation. We are strongly interested in understanding the role of the endosperm in establishing postzygotic hybridization barriers between plants of different ploidy as well as between related plant species. We also study the biogenesis and function of transposable element-derived small RNAs during reproduction. We are furthermore interested in understanding the role of transposable elements in generating transcriptional networks.
Genomic Imprinting in Plants
Genomic imprinting is an epigenetic phenomenon rendering alleles to be specifically active depending on their parent-of-origin. In plants, imprinted genes are mainly confined to the endosperm, a tissue regulating the nutrient transfer from the mother to the offspring. Our research focuses on elucidating the functional role of imprinted genes for endosperm development.
MADS-Box Transcription Factors Controlling Endosperm Development
MADS-box transcription factors (TFs) are ubiquitous in eukaryotic organisms and play major roles during plant development. Nevertheless, their function in seed development remains largely unknown. We have shown that the imprinted Arabidopsis thaliana MADS-box TF PHERES1 is a master regulator of paternally expressed imprinted genes.
Mechanism and Function of Endosperm Cellularization
Seed development in flowering plants is initiated by double fertilization of two female gametes by two sperm cells; fertilization of the haploid egg cell will generate the diploid embryo, while fertilization of the diploid central cell will generate the triploid endosperm. The endosperm serves to nourish and support the embryo by delivering nutrients acquired from the mother plant.
Plant Speciation Mechanism
Polyploidization is a widespread phenomenon among plants and is considered a major speciation mechanism. Polyploids have a high degree of immediate post-zygotic reproductive isolation from their progenitors, as backcrossing to either parent will produce mainly nonviable progeny. This reproductive barrier is called triploid block and is caused by malfunction of the endosperm.
Small RNAs Controlling Plant Reproduction
Plants that differ in ploidy are reproductively isolated by a hybridization barrier that is established in the endosperm, referred to as triploid block. Our work uncovered a new pathway leading to the formation of small RNAs from transposable elements that establish a hybridization barrier in the endosperm.