The role of WIH1/2 peptides in the transition from somatic to sporogenic fate in plants

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The goal of this project is to investigate the molecular mechanisms that regulate germline initiation in plants. Unlike animals where the germline is set apart from the soma early in embryogenesis, plants have evolved the fascinating ability to generate haploid gametes from somatic cells at the adult stage; a property that reflects the remarkable developmental plasticity of plant cells and that is of economic importance for seed production and plant propagation. In the female organs of the flower, a single somatic cell of each ovule becomes reprogrammed into a megaspore mother cell (MMC), which subsequently enters meiosis from which ultimately the egg cell is derived. The molecular pathways regulating the establishment of the MMC are largely unknown. During the first funding period, we discovered a novel molecular mechanism for the plant specific WIH1 (WINDHOSE1) and WIH2 peptides in initiating MMC development. Our data suggest a model where WIH peptides in the epidermis of the ovule act as novel tether molecules for RABA1-decorated vesicles that deliver the auxin transport protein PINFORMED1 to the plasma membrane. Subsequent accumulation of the phytohormone auxin in the epidermis is essential for the development of the underlying MMC. In the second funding period, we aim at testing this model and dissect the molecular principles of MMC regulation by WIH function. These studies will enhance our understanding of fundamental developmental processes that reprogram cell fate and initiate generative pathways, and at the same time contribute to concepts of reproductive strategies in economically important plant species.