Potential Roles Of Soil Pathogens In The Success Of Wetland Plant Species
Pathogenic soil fungi and oomycetes are known to play key roles in the distribution and abundance of plant species in natural systems. Soil pathogens are thought to be important both in maintaining the diversity of plant communities and in facilitating the dominance of invasive plant species. However, much of what we know about soil pathogens in natural systems comes from "black box" soil experiments in which the roles of soil fungi and oomycetes are inferred by either sterilizing soils or treating them with fungicides. While this genre of experiments has repeatedly established relationships between soil pathogens and plant dominance in the landscape, they fail to provide mechanistic insight. In addition, very little is known about the impacts of pathogens on wetland plant species as most research has focused on forest and grassland systems, despite the fact that wetlands are among the most highly invaded ecosystems. Through my dissertation research I sought to investigate soil fungal and oomycete communities with regard to wetlands and lay the groundwork for better understanding the roles of pathogens in the success of both native and non-native plant species. First, I determined if soil legacy effects of one plant species of interest, P. australis, negatively impact the performance of other plant species, a prerequisite if pathogen mediated plant-soil feedbacks are contributing to its invasive success. Second, I looked at the host range and virulence of the oomycetes associated with P. australis and other marsh plant species in an attempt to understand the potential of pathogenic species to affect marsh seedling establishment. Third, I characterized the fungal communities associated with seeds of various plant species overwintering in marsh wetland field soils to determine the effect of those fungi on seed viability and survival. Fourth, I coupled a reciprocal plant-soil feedback experiment with the characterization of soil fungal communities associated with locally dominant native and non-native plant species that displayed different feedback responses to better understand the potential relationships of specific fungal groups to invasive success.
Power,Alison G; Blossey,Bernd
Ph.D. of Plant Pathology
Doctor of Philosophy
dissertation or thesis