DISSERTATION RESEARCH: Phylogeny, Specificity, and Biogeography of Endophytic Xylariaceae in Liverworts

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Fungal endophytes are fungi that grow inside living plants, causing no apparent harm to the host. Although endophytes have been revealed in a wide variety of plants, the ecology of most endophytic relationships remains unexplored. Fungi in the family Xylariaceae are regularly identified as endophytes in a broad diversity of host plants throughout the world, yet almost nothing is known about whether they are host specific, or how particular species of endophytes are distributed geographically. This project will focus on the ecology and genetic relationships of fungi living endophytically in liverworts. It is difficult to identify endophytic fungi based on morphology, so molecular methods will be used to identify the fungi from their DNA sequences. Preliminary research has shown that Xylariaceae are dominant endophytes in liverworts, as in many other plants. Liverworts comprise one of the earliest groups of plants to colonize land, some 400 million years ago, and it has been suggested that fungi helped to facilitate this important step in the evolution of terrestrial organisms. Endophytes will be cultured from plants collected in North America, the Caribbean region, South America, Europe, and New Zealand. DNA sequences from endophytes will be identified by their similarity to known fungi; comparisons will be made against data contained in GenBank (National Center for Biotechnology Information), and databases available at Duke University. Geographic, ecological, and genetic information will be integrated in order to make inferences about host specificity, geographic structure, and relationships within and among endophytic and non-endophytic Xylariaceae and other fungi. Completion of this project will contribute to training a doctoral student and increase our knowledge of global fungal biodiversity, perhaps revealing previously undescribed species. This research will also provide a foundation for future work aimed at understanding the ecology and evolution of this potentially important plant-fungus interaction. The cultures obtained as a result of this research will be submitted to the American Type Tissue Collection , where they can be accessed for future experimental and comparative studies by other scientists.