Molecular mechanisms of cell polarity and development of distinct plasma membrane domains during formation of pollen apertures

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To perform their functions, cells often need to create regions on their surface which will differ from the surrounding areas in their protein and lipid composition. These regions are known as cellular domains. How cells direct molecules to specific positions and produce such domains is poorly understood. Pollen grains provide a beautiful example of a cells' ability to precisely form domains on their surfaces. Pollen surface is typically covered by a protective structure, pollen wall exine. However, in the majority of plants, certain regions on the pollen surface do not receive deposition of exine and instead develop into characteristic gaps, the apertures. To produce apertures, developing pollen consistently marks future aperture sites as different from the rest of the surface and protects them from exine deposition. This project will investigate molecular mechanisms through which pollen creates aperture domains. In the course of this project several young scientists (a postdoc as well as graduate and undergraduate students) will be trained. In addition, pollen biology will be used as a tool to engage and educate the general public through a variety of platforms, including activities at a local science museum, arts class, and a botanical garden.Formation of distinct cellular domains is critical for cell functions, but the mechanisms involved in creating these domains are still poorly understood. Pollen provides an excellent model for studying these mechanisms. In most plant species, the outer cell wall of pollen grains, called exine, is deposited on the pollen surface non-uniformly, with certain surface areas excluded from exine deposition and developing into characteristic openings, the apertures. Existence of apertures indicates the presence of tightly controlled mechanisms used by developing pollen to specify cellular domains. In this project, the roles of several aperture genes recently discovered in Arabidopsis will be studied to understand the mechanism of aperture formation. Through a variety of genetic, imaging, biochemical, and computational methods, the proposed work will define cell-biological and molecular events involved in this process. It will also explore the questions related to the evolution of pollen aperture diversity and will characterize molecular players that could be responsible for the interspecies similarities and differences in the process of aperture formation.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.