Polarization of Plant Cell Division by Receptor-Like Proteins

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Polarized (asymmetric) cell divisions produce cells with different properties and fates, as well as generate cellular diversity during the development of plants and other eukaryotes. However, very little is known about molecular mechanisms underlying polarized cell division in plants. We previously discovered a pair of receptor-like proteins, PAN1 and PAN2, that work together to polarize the asymmetric divisions producing subsidiary cells of stomatal complexes in the maize leaf epidermis, which regulate the exchange of oxygen, carbon dioxide, and water between the leaf and surrounding air. In this project, we will build on our earlier findings using tools of genetics, microscopy, proteomics, and biochemistry to advance our understanding of how PAN receptors promote the polarization of subsidiary mother cell divisions. Specifically, we will determine where PAN2 protein acts in the cell, elucidate the connection between PANs and other known regulators of cell polarity, analyze the role of PANs in the spatial regulation of secretion and/or endocytosis, and identify other proteins that PANs interact with to promote division polarity. Data generated by this project will be made available to the public through publications and publicly accessible websites, accessible via http://www.biology.ucsd.edu/labs/smith/; biological materials will be maintained by the principal investigator and distributed upon request. In addition to elucidating processes of fundamental importance for plant development, this project will also positively impact science education. A postdoctoral fellow, two graduate students, and multiple undergraduates will receive interdisplinary training through participation in this project. In addition, a week-long plant genomics laboratory module addressing California Life Sciences Standards for 7th grade will be implemented each year of the project period in two central San Diego public middle schools: Grant and Roosevelt. Participation in the module will benefit about 350 7th graders per year at these two schools, most of whom are underrepresented minority students at Roosevelt, where the minority enrollment is 80%.