Ectomycorrhizal fungi (EMF) are a diverse group of soil organisms that play an essential role in ecosystems by forming mutualistic relationships with trees. These fungi provide nutrients, such as nitrogen and phosphorus, in exchange for photosynthetically derived carbon sugars. There is little understanding of how EMF responds to environmental conditions and what genetic mechanisms are utilized to thrive under those conditions. One way EMF interact with their environment is through the breakdown of soil organic matter to acquire nutrients for their host (Frey, 2019). Previous work has suggested that EMF have a reduced capacity to decompose soil organic material compared to their saprotrophic ancestors, represented by the consistent loss of saprotrophic enzymes to decompose lignocellulose (Kohler et al., 2015). However, not all saprotrophic enzymes are lost, with the number of enzymes retained varying dramatically between species (Kohler et al., 2015). It is unknown whether EMF utilize the same genetic pathways to degrade soil organic matter as saprotrophs or if they use novel genes. In addition, it is unknown whether the remaining saprotrophic enzymes represent a diverse array of decomposition behaviors. To identify this, I conducted a transcriptomic assay of cultures of seven EMF species grown on varying types of media to distinguish genes used in degrading carbon and whether they vary in decomposition behavior. Mimicking environmental stressors and using transcriptomic analysis can allow a better understanding of how different EMF responds to climate-related stimuli. I extracted and sequenced mRNA from flash-frozen cultures to identify the genes that are differentially expressed in the presence or absence of an ecological stressor. Through comparative transcriptomics, I expect to identify contrasting patterns of gene regulation in response to stressors. Through these analyses, we will gain a better understanding of gene regulation and behavior in response to environmental conditions, which are essential for understanding why EMF are so diverse.