Wild type ovule

Germ cell formation in plants

Coordinating the behaviors of different cell populations is essential for multicellular development. One important example for this can be found in ovule development in higher plants. Ovules are specialized somatic structures that ultimately give rise to the egg cell and harbor the developing embryo. Of course, seed production is of the uttermost importance in agronomy, and understand the regulatory mechanisms has a great potential to improve breeding and food production. Two neighboring cell groups of the ovule, the nucellus and the chalaza, coordinately produce structures that eventually form an intimate physical and functional unit, the seed  (Gross-Hardt et al., 2002). In contrast to animals, germ cells in plants are not derived from a germline separated early in development, but are formed from diploid somatic cells. We would like to understand how this transition from mitotic somatic cells to a meiotic pathway is accomplished, and how it is restricted to one single cell in each ovule. We isolated a novel group of peptides, named WINDHOSE (WIH), a potential adaptor protein in signaling processes (Lieber et al 2011). Our current goal is to elucidate the molecular mechanisms how WIH proteins regulate the transition from a somatic to a germ cell.

In wild type ovules (middle) the embryosac is protected by the integuments. In mutant ovules no integuments are initiated, resulting in a "naked" ovule (right). Scanning electron microscopy images.

Selected publications on germ cell formation

Lieber,D., Lora, J., Schrempp, S., Lenhard, M., and Laux, T. (2011) Arabidopsis WIH1 and WIH2 genes act in the transition from somatic to reproductive cell fate. Current Biol. 21, 1009-1017

Deyhle, F., Sarkar, A., Tucker, E.J., and Laux, T. (2007). WUSCHEL regulates cell differentiation during anther development. Dev. Biol. 302, 154-159.

Sieber, P., Gheyselinck, J., Gross-Hardt, R., Laux, T., Grossniklaus, U., and Schneitz, K. (2004). Pattern formation during early ovule development in Arabidopsis thaliana. Dev. Biol. 273, 321-334. 

Gross-Hardt, R., Lenhard, M., and Laux, T. (2002). WUSCHEL signaling functions in interregional communication during Arabidopsis ovule development. Genes Dev 16, 1129-1138.