ABR: Molecular Systematics of Grass Symbionts of the Fungal Family Clavicipitaceae (Hypocreales)

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9707427 Schardl Building upon an impressive record of recent research, Dr. Schardl of the University of Kentucky continues his taxonomic and ecological studies of symbiotic ascomycetous fungi that infect grass plants. These fungal relatives of the infamous 'ergot' fungus live inside various turf grasses and other species, and transmit their spores either asexually through the grass seed ("vertical" infection of the grass's progeny) or following sexual reproduction, through fly-mediated contagion ("horizontal" infection of other grasses in the habitat). The sexually reproducing fungal species have usually been classified in the genus Epichloe, of the Clavicipitaceae family, while the asexual or conidial anamorphs have usually been named in the genus Neotyphodium. Confusion in the taxonomy has, until now, obscured the interesting symbiotic ecology of the fungus and its grass hosts. With DNA sequencing of several targeted nuclear genes, of samples collected over a wide geographical range, and with laboratory and garden tests of mating success between fungal isolates, Dr. Schardl continues to analyze the phylogenetic relationships of Epichloe and Neotyphodium species and suspected relatives. In turn, these genealogically related groups or clades of fungi are correlated with their host grass plants, to determine whether this symbiotic association has closely tracked the history of speciation of the grasses ("co-speciation") or whether new grass hosts are infected, and if so, whether mostly by sexual or by asexual forms of the fungus. New molecular methods of DNA sequencing allow fine-scale analysis of genealogical or phylogenetic relationships among the separately named sexual and asexual forms of fungi, and are being applied by Dr. Schardl in imaginative ways to an ecologically fascinating system of fungal symbionts of turf grasses and related grass species. Whether the fungi "track" the history of speciation of their grass hosts, whether asexual morphs originate from sexual fungal forms or th e opposite, and whether fungal species hybridize to produce some of the currently documented Neotyphodium anamorphs, are just some of the questions being pursued in this renewed award.