Characterization of Pollen Tube Repulsion in Arabidopsis thaliana

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Dr. Ravishankar PalaniveluProposal #: 0723421Characterization of pollen tube repulsion in Arabidopsis thalianaCell-cell interactions are important during development of all eukaryotic organisms. One particularly unique example involves interactions between a migrating cell and those that are in its path. Avoiding inappropriate interactions is essential for a navigating cell to reach its intended target. In humans, disruption in this process results in polyspermy and neuronal defects. In plants, cell avoidance is exceptionally important during reproduction when pollen tubes avoid egg-bearing ovule structures that have already been fertilized. However, since pollen tube repulsion occurs within opaque floral structures, the dynamic nature of these interactions and the signals that mediate them remain poorly characterized. Recently, a simple biological assay was developed to directly observe pollen tube-ovule interactions. This assay revealed that a short-range repulsion signaling is initiated from an ovule soon after a pollen tube enters it. Capitalizing on this finding, a variety of cell biological, molecular, genetic, biochemical and computational approaches are proposed to conduct a thorough characterization of pollen tube repulsion in the model plant, Arabidopsis thaliana. Insights gained on avoidance of spurious fertilization events could ultimately help in developing genetically modified pollen that cannot fertilize native species, which is an impediment breeders must overcome while developing transgenic crop varieties. This study will generate novel image analysis algorithms that will benefit other migratory cell models such as neurons and dictyostelium, and an open-access educational website on plant reproduction that can be freely used by educators, students, and the public. Biology faculty from Pima Community College, a non-Ph.D. granting institution, and undergraduates, especially those from under represented Native American, African-American and Hispanic communities, will carry out parts of this project. Exposure to biology and hands-on training in research will motivate them to choose a career in science.