Control of Entry into the Female Germline in Maize

点击翻译按钮获取中文摘要

One of the major developmental phase transitions in eukaryotes is meiosis. Due to its far-reaching consequences, i.e. reduction of the chromosome set by half coupled to recombination and the new assembly of chromosome sets, the decision when and which cells undergo meiosis is tightly controlled. In contrast to animals that specific a cell lineage (germline) leading to the formation of meiocytes early during embryogenesis, flowering plants reprogram somatic cells in reproductive organs late in development to produce an archesporial cell from which a meiocyte is derived and with that initiate a germline that leads to the production of gametes. Very little is known about germline initiation in plants, especially in crops, and none of the regulators of meiotic entry known from animals and yeast are conserved in plants. A few genes have been identified in maize, rice, and mostly Arabidopsis that play a role in the specification of archesporial cells and meiocytes. However, the corresponding studies also show that the mechanisms of germline initiation are likely diversified in flowering plants. An emerging principle, however, appears to be that the setup of the germline requires the formation of stem cell-like cells as for instance seen by the necessity of the function of the stem cell factor WUSCHEL for this process in Arabidopsis. Here, we will study the cellular specification events that ultimately lead to the formation of female meiocytes in the crop species maize. In close collaboration with the other members of this research unit, we will address the question how pluripotent stem cell-like cells are reprogramed to enter the female germline. To reach this goal, we will first generate a cytological framework of germline entry by applying a recently established live cell imaging approach. This work will be complemented by single cell sequencing of young ovule cells to follow their developmental trajectories during germline establishment. Finally, we will challenge germline differentiation by specific gain-of-function and loss-of-function approaches. Together with the other consortium members we will then develop an integrated view on the initiation, maintenance and termination of stem cell-like cells during crop development.