General

A major characteristic of flowering plants (Angiosperms) is the double fertilization process, which was discovered more than 100 years ago by Russian and French scientists. This reproduction process takes place within the haploid female gametophyte (embryo sac; see image at the right; adapted from Diboll and Larson, 1966), which, in contrast to lower plant species, is reduced to only a few plant cells. The embryo sac consists of the two female gametes, egg (EC) and central cell (CC), two additional cells (synergids, SY) that form the egg apparatus together with the egg cell and the so called antipodal cells (AN) opposite of the egg apparatus. During fertilization, one sperm cell fuses with the egg cell generating the zygote, which initiates a coordinated developmental program of cell divisions and cell specifications, finally resulting in an embryo containing different cell types, tissues and organs. The second sperm cell fuses with the central cell, giving rise to the endosperm, known to us as the flour of cereals.

The differentiation of the female gametophyte from a single progenitor cell is, from a cell biological perspective, one of the most spectacular differentiation processes known in higher plants. Understanding the molecular mechanisms underlying the establishment of polarity and cell identity within the embryo sac, is one focus of our research team. We are also interested to identify the molecules that male (pollen) and female gametophytes use for communication and try to elucidate the mechanisms required to induce the embryonic program. We are using maize and wheat as model plant species to identify key genes involved in the processes described above. The function of some genes with homologs in the "Model Plant Species" Arabidopsis thaliana will be studied and Tripsacum dactyloides is included as a model system to investigate parthenogenesis (fertilization independent embryo development) as a component of apomixis (asexual reproduction through seeds).