RUI: The cell biology of pectin dynamics in the Charophycean Green Algae: Homogalacturonan secretion in the model organism, Penium margaritaceum

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Intellectual Merit Cell wall polymers are important biochemicals in the growth, development and survival of green plants and constitute the most abundant biochemicals on the planet. Pectins represent one of the major classes of cell wall polymers and function in regulating cell wall expansion and cell growth as well as cell wall porosity and uptake of key ions. The synthesis, secretion and post-secretory remodeling of pectins represent key subcellular events in the life of a plant cell and specific studies to elucidate these processes have only just begun. Pectins are found in all land plant groups and have been recently characterized in the Charophycean Green Algae (CGA). The CGA represent the extant group of green algae that is ancestral to modern-day land plants. In this project, a model organism from the CGA, Penium margaritaceum, is employed to study quantitative aspects of pectin secretion, the specific role of subcellular components in pectin and cell wall processing, and the role of a key pectin-modifying enzyme. This project applies various experimental, microscopy-based and immunolabeling technologies to studies of the endomembrane system, cytoskeletal/cytomotile networks, and cell surface phenomena that are intricately involved in the secretion of pectins to the cell wall. The results of this project will be synthesized and used in the construction of models of pectin dynamics in plants and will provide insight into cell wall polymer processing by green plant cells, the coordinated interaction of multiple subcellular systems in defined secretory activities, and the evolution of primitive green plants. Broader Impacts This RUI project will provide summer research opportunities for 4 undergraduates and semester-based research opportunities for 6-10 undergraduates at Skidmore College. The project also will promote the integration of research in education as components of the project will be used to enhance instruction and support laboratory experiences in courses as Plant Biology, Plant Physiology, and Biological Electron Microscopy. The project also includes outreach experiences for pre-college students. Specifically the outreach plan includes a series of active presentations by the PI and Skidmore biology majors to elementary students and their teachers on the microscopic world. In addition the PI and his students will lead Saturday field trips to wetlands for high school and middle school students and their teachers. The field trips will include activities in collecting microscopic specimen followed by identification exercises with the microscope. The results of the study will be broadly disseminated through student/PI presentations and publications, outreach programs, and the recently established CGA website at Skidmore College.