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Systemic endophytes, fungi found in the roots, shoots and seeds of a single plant, have the opportunity to influence plant growth and success at multiple life stages. Vertical transmission of systemic endophtyes from parent plant to seed can indicate strong mutualistic interactions (Clay et al. 1990). These mutualisms occur most often in domesticated grasses rather than uncultivated populations such as invasive cheatgrass (Faeth et al. 2002). Recent inoculation assays of cheatgrass showed systemic endophytes influence disease occurrence. This suggests more research is needed to understand the complexity of this host-symbiont relationship.

We cultivated two systemic endophytes of cheatgrass, Thielavia and Microdochium, isolated from a previous study. We inoculated cheatgrass plants with U. bullata and either systemic endophyte to determine if these fungi reduce disease incidence. Four treatments were tested: plants inoculated only with U. bullata (n=118), plants inoculated with both U. bullata and a species in the genus Thielavia (n=121), plants inoculated with U. bullata and a species in the genus Microdochium (n=164), and a control group inoculated with sterile water (n=125). Figure 1: The proportion of plants infected with U. bullata in each treatment. Inoculations with U. bullata and Microdochium resulted in an approximately 48% lower infection rate than plants inoculated with U. bullata alone (Figure 1). In contrast, inoculation with U. bullata and a fungal isolate in the genus Thielavia resulted in an approximately 43% higher infection rate than plants inoculated with U. bullata alone. A chi-square test showed that differences among group distributions were significant, χ2 (3) = 55.7015, p < .001. The different interactions between systemic endophytes and U. bullata demonstrate the complex relationships of endophytes and their host plants. Many studies provide evidence that endophytes can act as defensive mutualists against herbivores (Saikonnen et al. 2010), but few examine the potential of endophytes to inhibit fungal pathogens in grasses. Subsequent trials with increased replication will give us a better picture of the complex interactions between cheatgrass and its fungal community. 0

We cultivated two systemic endophytes of cheatgrass, Thielavia and Microdochium, isolated from a previous study. We inoculated cheatgrass plants with U. bullata and either systemic endophyte to determine if these fungi reduce disease incidence. Four treatments were tested: plants inoculated only with U. bullata (n=118), plants inoculated with both U. bullata and a species in the genus Thielavia (n=121), plants inoculated with U. bullata and a species in the genus Microdochium (n=164), and a control group inoculated with sterile water (n=125). Figure 1: The proportion of plants infected with U. bullata in each treatment. Inoculations with U. bullata and Microdochium resulted in an approximately 48% lower infection rate than plants inoculated with U. bullata alone (Figure 1). In contrast, inoculation with U. bullata and a fungal isolate in the genus Thielavia resulted in an approximately 43% higher infection rate than plants inoculated with U. bullata alone. A chi-square test showed that differences among group distributions were significant, χ2 (3) = 55.7015, p < .001. The different interactions between systemic endophytes and U. bullata demonstrate the complex relationships of endophytes and their host plants. Many studies provide evidence that endophytes can act as defensive mutualists against herbivores (Saikonnen et al. 2010), but few examine the potential of endophytes to inhibit fungal pathogens in grasses. Subsequent trials with increased replication will give us a better picture of the complex interactions between cheatgrass and its fungal community. 0

About the Author

Lorinda Bullington

Lorinda is currently a Ph. D. student at the University of Montana, studying systems ecology. She also has a master’s degree in molecular ecology, a B.S. degree in microbiology, and a certificate in bioinformatics. Her research investigates how plant-associated microbial communities (plant microbiomes), influence plant growth, defensive chemistry, disease, and nutrient cycling. Lorinda comes from three generations of small-scale Montana loggers and is particularly interested in microbial communities in forest ecosystems. She has published research on fungi associated with native white pines and their influence on tree defensive chemistry and the invasive pathogen Cronartium ribicola, which causes white pine blister rust disease. She also works in collaboration with others at UM studying the influence of bark beetle infestations on fungal decomposer communities, with implications on nutrient turnover and carbon sequestration in forests.
In addition to her own research, Lorinda often assists other researchers in bioinformatics analyses and is currently working on multiple diet-barcoding studies to better understand food web ecology and dynamics across the landscape. For a complete list of Lorinda’s publications, click here.