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ABSTRACTEnvironmentally damaging invasive plants can also serve as reservoir hosts for agricultural pathogens. Microstegium vimineumis an invasive C4 annual grass that is present throughout the midwestern and eastern United States. It can reach high densities in disturbed areas such as crop-forest interfaces, which creates the potential for pathogen spillover from M. vimineumto agricultural crops and native plants. A previous study that surveyed disease on M. vimineumfound a large-spored Bipolarisspecies that was widespread on M. vimineumand also isolated from co-occurring native grasses. Here, we report that the large-spored fungus isolated from M. vimineumand the native grass Elymus virginicusis Drechslera gigantea, based on comparison with published descriptions of morphological traits, and establish that D. giganteais a pathogen of M. vimineumand E. virginicus. We review the phylogenetic placement and taxonomic history of D. giganteaand propose that it be reassigned to the genus Bipolarisas Bipolaris gigantea.

Periglandula ipomoeaeand P. turbinae(Ascomycota, Clavicipitaceae) are recently described fungi that form symbiotic associations with the morning glories (Convolvulaceae) Ipomoea asarifoliaand Turbina corymbosa, respectively. These Periglandulaspecies are vertically transmitted and produce bioactive ergot alkaloids in seeds of infected plants and ephemeral mycelia on the adaxial surface of young leaves. Whether other morning glories that contain ergot alkaloids also are infected by Periglandulafungi is a central question. Here we report on a survey of eight species of Convolvulaceae (Argyreia nervosa, I. amnicola, I. argillicola, I. gracilis, I. hildebrandtii, I. leptophylla, I. muelleri, I. pes-caprae)for ergot alkaloids in seeds and associated clavicipitaceous fungi potentially responsible for their production. All host species contained ergot alkaloids in four distinct chemotypes with concentrations of 15.8–3223.0 μg/g. Each chemotype was a combination of four or five ergot alkaloids out of seven alkaloids detected across all hosts. In addition, each host species exhibited characteristic epiphytic mycelia on adaxial surfaces of young leaves with considerable interspecific differences in mycelial density. We sequenced three loci from fungi infecting each host: the nuclear rDNA internal transcribed spacer region (ITS), introns of the translation factor 1-α gene (tefA) and the dimethylallyl-tryptophan synthase gene (dmaW), which codes for the enzyme that catalyzes the first step in ergot alkaloid biosynthesis. Phylogenetic analyses confirmed that these fungi are in the family Clavicipitaceae and form a monophyletic group with the two described Periglandulaspecies. This study is the first to report Periglandulaspp. from Asian, Australian, African and North American species of Convolvulaceae, including host species with a shrub growth form and host species occurring outside of the tropics. This study demonstrates that ergot alkaloids in morning glories always co-occur with Periglandulaspp. and that closely related Periglandulaspp. produce alkaloid chemotypes more similar than more distantly related species.