Theses and Dissertations Collection

Microorganisms form endosymbiotic relationships with hosts. Better understanding of fungal microbial communities is important to science as these microorganisms affect larger ecosystems. This thesis explores fungal symbionts in woody trees, mainly black cottonwood, in the Pacific Northwest.

In the first chapter, we report a lichen Xanthoria parietina in Idaho for the first time. Non-native lichens have the ability to decrease native lichen diversity through displacement of local species. This coastal lichen has is now found in inland cities but is restricted to urban areas.

Next, we found the causal agent of an unknown leaf blight along the Yakima River, Washington. With multiple surveys and greenhouse assays, we see causal agent is an endophyte that may cause disease only under stress.

Lastly, we clarify the ambiguity of functional roles of endophytes in multiple hosts. Sampling shows multiple incidences of endophytes as pathogens in other hosts and a greenhouse assay confirms this.