The Evolution and Ecology of Translocative Cord-Forming Saprotrophic Fungi

Filamentous Basidiomycete fungi drive the nutrient cycling and decomposition of fallen trees within forest ecosystems. In response to the patchy nature of nutrient availability, certain species of taxonomically diverse fungi use structures of aggregated mycelium – commonly known as cords – to transport nutrients over distance. Mycelial cords have been associated with efficient resource translocation, pigment, and volatile production, which is linked to antagonistic ability and resistance to grazing. The underlying genetic signatures and regulation of cord formation are not known. This study used comparative genomics to examine genetic signatures between fungi with corded and non-corded morphology, using Principal Component Analysis and t-test. Cord formation is a morphology that has independently emerged within the basidiomycete lineages; therefore, it was hypothesised that a genetic signature for the corded lifestyle might be present in genes associated with membrane transporters, CAZymes, peptidases, secondary metabolite clusters, and transcription factors. The Principal Component Analysis and t-test of gene counts between 16 species of fungi (eight cord-forming, eight non-cord forming) representing six orders within the Agaricomycetes showed that higher levels of individual transporters, CAZymes, and peptidases were in the non-cord forming species. The impact of gene complement measurements in trait evolution and ecological trade off implications for fungal colony morphology are discussed