Trophic Modes of Moss-associated Macrofungi Galerina and Rickenella and Their Impact on Moss Mycobiome

Trophic Modes of Moss-associated Macrofungi Galerina and Rickenella and Their Impact on Moss Mycobiome

Chia-An Cho1,2, Wen-Yuan Kao1 and Ko-Hsuan Chen2*

1Institute of Ecology and Evolutionary Biology, National Taiwan University, Taipei, Taiwan

2Biodiversity Research Center, Academia Sinica, Taipei, Taiwan

*Email: kohsuanchen@gate.sinica.edu.tw

Our study focuses on Rickenella fibula and one species of Galerina that fruit on the moss Plagiomnium acutum, to understand moss-fungal interaction. We aim to address the following questions: (1) Do R. fibula and Galerina sp. grow inside P. acutum? (2) Are there carbon or nitrogen exchanges between P. acutum and these two fungi? (3) Do R. fibula and Galerina sp. cause physiological changes in P. acutum? (4) Are the mycobiome compositions of P. acutum bearing Galerina sp. and R. fibula different? Through histological sectioning and DNA sequencing, we found that both Galerina sp. and R. fibula grew inside P. acutum, primarily in the rhizoid tissues. Then, we compared the natural abundance of carbon (𝛅13C) and nitrogen (𝛅15N) stable isotopes from fruiting bodies of Galerina sp. and R. fibula with P. acutum. Both fungi had more negative 𝛅13C values than P. acutum, suggesting they may obtain carbohydrates from the living moss. However, we found no evidence indicating that these fungi provide nitrogen to the moss. According to the chlorophyll fluorescence measurements, these two fungi did not negatively affect the photosynthetic potential of the moss. Finally, amplicon sequencing revealed distinct mycobiomes in R. fibula-bearing and Galerina sp.-bearing moss rhizoids. In conclusion, both Galerina sp. and R. fibula are weak parasitic endophytes of P. acutum and affect mosses’ mycobiome assemblies. Various lines of our investigation highlight that the interaction between moss-associated fungi and mosses may be more closely intertwined than previously thought.