Exocyst-Mediated Pathways to the Plant Cell Surface

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INTELLECTUAL MERITThis project seeks to understand the mechanisms by which plant cells control the delivery of proteins and other functional molecules to their outer surface, the region defined by the plasma membrane and surrounding cell wall. This process is known as vesicle trafficking, as proteins are produced within the cell, packaged into small, membrane-bound carriers (vesicles), and then moved to the plasma membrane for final delivery. This process is important because: 1) it is the primary mechanism used to build and to control the plant cell interface with its outside environment, which can affect how the plant interacts with harmful or beneficial microbes; 2) it is crucial for cell growth; 3) it is a regulator of cell-cell communication between cells; and 4) it is crucial for the acquisition of nutrients from the surrounding environment via specialized plasma membrane-localized protein transporters. The molecular mechanisms regarding how vesicle trafficking are controlled are not well understood. One player that appears likely to control this process in plant cells is the eight-protein exocyst complex, which provides spatial regulation at the plasma membrane for vesicle trafficking. This project uses the Arabidopsis root hair as a model and investigates the exocyst-mediated vesicle trafficking pathway (EMVT). EMVT is required for proper growth of the root hair, a key structure for nutrient acquisition. The project seeks to understand how root hair growth relies on EMVT through: 1) Characterization of exocyst interactions with other known components of the vesicle trafficking system; and 2) Molecular identification of a new gene (NERD1) which interacts functionally with the exocyst in the Arabidopsis root hair. The project should build a deeper understanding of how the function of plasma membrane-targeted molecules is enabled and controlled, and how precise patterns of cellular growth are affected.BROADER IMPACTSThe knowledge generated in this project may have broad implications for plant physiology and development. Due to its hypothesized connection to the plasma membrane, EMVT may help mediate interactions between root and soil. Thus, this work could inform applied work that seeks to manage plant responses to abiotic stress induced by the surrounding environment (e.g. drought, salinity, and nutrient-poor soils), to pathogens, and to interactions with the rhizosphere microbial community. In addition, the project will train a postdoctoral researcher in integrating genetic, cell biological and next-generation sequencing approaches, and will mentor undergraduate students in plant genetic research. Finally, this project will support outreach efforts to high school students through the Apprenticeships in Science and Engineering program at Oregon State University.