Master of Science (MS), Wright State University, 2009, Biological Sciences

Garlic mustard is an invasive Eurasian biennial that has rapidly spread throughout the United States. In Southwestern Ohio, many garlic mustard populations are infected with the powdery mildew Erysiphe cruciferarum that can reduce the growth and fitness of garlic mustard. E. cruciferarum was assessed using a Decision Tree in regards to its potential use as a biological control agent. I determined the distribution of E. cruciferarum on garlic mustard and I determined the potential risk of E. cruciferarum to native Brassicaceous species and selected crops. I surveyed 19 parks in Southwestern Ohio and recorded the number of diseased garlic mustard and aspect at every population and then made a distribution map of disease incidence of E. cruciferarum on garlic mustard using GIS ESRI (ArcMap) software. My distribution survey showed a random distribution of E. cruciferarum infection on garlic mustard with disease incidence decreasing away from Dayton, Ohio. Aspects with higher disease incidences were level and facing southeast and were significantly different than northwest facing aspects. Five native spring ephemeral species were surveyed in the field and then obtained from local wooded areas in May 2008. Individual plants were transplanted in the greenhouse and then exposed to infected garlic mustard plants. The native plants surveyed showed no obvious signs of E. cruciferarum infection in the field. All of the native plants subjected to powdery mildew under greenhouse conditions became mildly infected with E. cruciferarum. Twelve crops in the family Brassicaceae along with 2 crops in the Fabaceae and Solanaceae families were planted and inoculated with E. cruciferarum and only one cultivar, Savanna Mustard (Brassica juncea), became infected with powdery mildew. A distribution survey showed the distribution of E. cruciferarum infection on garlic mustard with disease incidence decreasing away from Dayton, Ohio. Populations located on level ground or facing southeast had (open full item for complete abstract)

Committee: Don Cipollini PhD (Advisor); Thomas Rooney PhD (Committee Member); Songlin Cheng PhD (Committee Member); David Goldstein PhD (Other); Joseph F. Thomas, Jr. PhD (Other) Subjects: Biology; Botany; Ecology

Doctor of Philosophy, The Ohio State University, 2020, Plant Pathology

The characterization of plant germplasm has tremendous potential to help address the many challenges that the field of plant health is facing, such as climate change continuously modifying the regions of previously known disease occurrence. The worldwide trade of the plant genus Phlox represents an important revenue for the horticultural industry. However, Phlox species are highly susceptible to the fungal disease powdery mildew (PM), and infected materials shipping across borders accelerate the risk of disease spread. Through collaboration with laboratories in the U.S., we investigated the genotypic and phenotypic diversity of a PM population to better understand its capacity to adapt to new environments and new resistant hosts. To do this, we developed tools to grow and study PM pathogens of Phlox in vitro, and then used whole genome comparison and multilocus sequence typing (MLST) analysis to study the genetic structure of the population. Additionally, we explored Phlox germplasm diversity to identify a range of plant responses to PM infection by comparing disease severity progression and length of latency period of spore production across a combination of Phlox species and PM isolates in vitro. Consistent with the literature, our results suggest that compared to most plant pathogenic fungi in the Ascomycota, Golovinomyces magnicellulatus, causal agent of PM, has larger genomes (about 130 Mb) with high repetitive content (about 40%) and a fewer number of protein-coding genes (about 8000). We found a lack of population structure and genetic diversity, despite diverse phenotypic responses to Phlox germplasm screening. Interestingly, we identified 7 putative secreted proteins, which are predicted to be involved in the infection process, that are differently distributed between the G. magnicellulatus genomes analyzed. We hypothesize that variation in predicted secreted proteins is at the basis of the differences observed in genetic and phenotypic diversity. Our resul (open full item for complete abstract)

Committee: Francesca Hand PhD (Advisor); Pablo Jourdan PhD (Committee Member); Thomas Mitchell PhD (Committee Member); Pierce Paul PhD (Committee Member); Jason Slot PhD (Committee Member) Subjects: Plant Pathology

Doctor of Philosophy, The Ohio State University, 1980, Graduate School

Committee: Not Provided (Other) Subjects: Agriculture

Master of Science (MS), Wright State University, 2012, Biological Sciences

Garlic mustard (Alliaria petiolata) has been previously found to be significantly affected negatively by powdery mildew (Erysiphe cruciferarum). While we could not significantly corroborate those findings we did find evidence that E. cruciferarum does inhibit A. petiolata's allelopathic and competitive effects which benefits some target neighbor species such as Impatiens capensis and Elymus canadensis. We also found that the inhibition of A. petiolata by E. cruciferarum had negative consequences on another neighboring invasive species (Lonicera maackii) compared to those grown next to uninfected A. petiolata. Acer saccharum, a slow-growing species had no effect between neighbors. Sterilization treatments had variable effects on target plants, many of which mirror the effects which allelopathic plants (A. petiolata) that disrupt soil microbes seem to have. Sterilization inhibited growth of E. canadensis through the destruction of beneficial effects from microbes, while increasing the growth of L. maackii by inhibiting the pathogenic effects of microbes.

Committee: Don Cipollini Ph.D. (Advisor); James Amon Ph.D. (Committee Member); Thomas Rooney Ph.D. (Committee Member) Subjects: Biology; Botany; Conservation; Ecology; Environmental Management; Forestry; Plant Biology; Plant Pathology; Plant Propagation; Plant Sciences; Wildlife Conservation