DISSERTATION RESEARCH: Assessing the Importance of Trophic Lability for Fungal Endophytism Using the Moss Dicranum scoparium and its Associated Fungi

Plants are essential because they are the main source of carbon for terrestrial ecosystems. Similar to humans, and animals in general, plants harbor diverse microbial communities, including fungi. Mosses are a major component of boreal, arctic and alpine vegetation, which are most drastically impacted by environmental variation. They are known to host diverse fungal communities, living inside plant tissues (endophytic), such as leaves, without causing any visible symptoms. Endophytic fungi can actually help living plants in various ways, including the improvement of nutrient uptake and protection from pathogens. However, fungi are also known to be proficient decomposers of dead plant material. Switches between these functional states by fungi might be dynamic and potentially regulated by abiotic and biotic factors. Understanding the circumstances and mechanisms by which these functional transitions occur will greatly improve knowledge of plant-fungus interactions and their roles as symbiotic entities to maintain nutrient cycling and ecosystem functions. The researchers will participate in various outreach activities, including the annual Darwin Day exhibition event at the North Carolina Museum of Natural Sciences. This grant will greatly improve the co-PI's Ph.D. dissertation, and contribute to the development of an independent research program for a successful academic career.

Previously, the researchers have examined endophytic fungal species and their function across a senescence gradient within moss plants using an innovative metatranscriptomic approach. Although active fungal species were found to be structured according to the senescence gradient of the moss, several fungi inhabit both the living (top) and decomposing (bottom) portions of the plant, providing multiple candidate fungal species to study trophic transitions between symbiotrophism and saprotrophism. The researchers will isolate some of these fungi in pure cultures and use them in an experiment designed to quantify the effects of focal fungal strains on living and dead moss tissues. Using co-culture experiments of these fungi with moss plants, this project will characterize the phenotypic, and transcriptomic, responses of mosses to their associated fungi. This research will use also the same moss-fungus system to monitor differential gene expression associated with a switch between symbiotrophism and saprotrophism by three very different fungal species.