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UBC Theses and Dissertations

Networks of communication : defense-related signal transfer between tree seedlings via mycorrhizal networks and an educational mycorrhizal-focused video game Amerongen Maddison, Julia


The majority of terrestrial plants associate with fungi in symbiotic resource-exchange relationships called mycorrhizae. Mycorrhizal networks (MNs) arise when the same fungus is connected to multiple plants, allowing for interplant resource transfer and impacting ecosystem functions. Recent work suggests MNs also transfer defense-related information from pathogen-, herbivore-, or mechanically-damaged plants to unharmed neighbors. I investigated the defense pathways involved in defense-related signal transfer in ectomycorrhizal systems. Paired Douglas-fir seedlings were grown with varying levels of belowground connectivity (soil water only; soil water and MNs; soil water, MNs, and roots), and a defense response was stimulated in donor seedlings by methyl jasmonate. After 24 and 48 hrs, I measured expression of two regulatory genes on the jasmonate and ethylene pathways. Receiver response was unrelated to hormone treatment of donors in either gene, but the jasmonate response of donor and receiver pairs was correlated across treatments. Positive expression of both genes across donors and receivers and pervasive presence of spider mites suggested signal transfer may either have not occurred or been masked by already ongoing defensive responses. Results indicate the complexity of these systems, and further work is needed to better characterize defense signal transfer via ectomycorrhizal networks. Because of the importance of these mycorrhizal systems to ecosystem functioning, it is crucial that resource managers and scientists have a good understanding of mycorrhizal ecology. However, lower student interest in plants and fungi combined with difficulties visualizing belowground processes present challenges for teaching and learning mycorrhizal concepts. To address this, I co-created the digital plant-centric action-based game Shroomroot for use in lower level postsecondary settings. I conducted a pre-test/post-test evaluation of Shroomroot in a 2nd year postsecondary Introduction to Soil Science course. Students’ knowledge of mycorrhizal ecology increased after playing Shroomroot, and engagement with mycorrhizal content tended to increase after gameplay. These exploratory results suggest positive potential for action-based plant-oriented digital games in the higher education classrooms. Both studies focus on improving our understanding of mycorrhizae and mycorrhizal networks, ecologically and pedagogically. Greater understanding of mycorrhizae has the potential to improve our multi-faceted relationships with the ecosystems upon which we depend.

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