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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 Bullington comes from three generations of small-scale Montana loggers, or as her grandfather put it, "the first environmentalists.” Not wanting to leave this beautiful state, Lorinda attended the University of Montana, earning a B.S. in Microbiology in 2010. Family traditions inspired a love of forests and nature, and during her junior year of college, Lorinda began working at MPG North, studying microbial communities associated with Western white pine trees and how those microbes can influence tree health and deer browse in forest ecosystems.

After college, Lorinda continued this line of research, working full time at MPG Ranch. She experimentally inoculated plants with microbes, in the field, and in the greenhouse, to enhance ongoing restoration projects and learn more about plant-microbe interactions. This lead to follow up studies exploring microbial communities associated with five-needle pines in relation to tree physiology, genetics, and disease resistance. Through this research, Lorinda recently earned an M.I.S. degree at the University of Montana, focusing on plant molecular ecology. At MPG Ranch she is involved in both original research and bioinformatics, combining biology and computer science to better interpret molecular data. When not working, Lorinda enjoys going to the gym, gardening and getting outside.