Abstract Detail

Ecological Consequences and Mechanisms of Fungal-Fungal Interactions

Song, Zewei [1], Vail, Andrew [2], Sadowsky, Michael [2], Liew, Fengjin [1], Schilling, Jonathan [1].

Fungal competition for wood in the face of endophytes: Glory and consequence.

Wood decomposition is primarily fulfilled by brown rot and white rot fungi in temperate and boreal forests. The competitive balance between these fungi determines the pathways of element cycles in dead wood, the release rates of carbon to the atmosphere, and the quality of forest soils. These fungi colonize wood via spores and soil mycelia, but also by infecting living trees where they reside latent as endophytes, adding complexity to predicting the interaction within microbial communities. These interactions will likely be influenced by climate change, but the response still unclear. My talk will touch on several projects in our lab focused on quantifying the presence of these fungi in situ as well as connecting their presence to the consequences of competitive success. Particular focus will be on the role of priority in colonization, including as endophytes, using a common competitive scenario in paper birch between the brown rot fungus Piptoporus betulinus and white rot fungus Fomes fomentarius. Over five-months of decomposition, we tested competitive dynamics and the role of endophytes by eliminating or maintaining the native endophytic community at two temperatures (25°C and 30°C). The competitive outcomes were confirmed using quantitative PCR on the relative abundance of P. betulinus, F. fomentarius, bacteria, fungi and Basidiomycota. These outcomes were also linked to the consequences on the wood residues formed and the carbon release rates by sampling water content, dilute alkali solubility, pH, and loss rate of dry mass, carbohydrates and lignin. In each of these studies, the competitive outcomes between a brown and white rot fungus for the same wood substrate type were flexible, depending on the timing of colonization and inoculum potential. Temperature could affect the outcomes of competition but these effects were far less than the role of native endophytic communities. Presence of endophytes significantly reduced the decay rate and effectively slowed the colonization of external fungi. However, these communities residing in healthy xylem tissue could still cause significant mass loss. The abundance of Basidiomycota decreased in the presence of endophytes and at higher temperature, resulting a negative relationship between mass loss and Bacteria:Basiodiomycota ratio. These community shifts left a signature of rot type that clustered between typical brown rot and white rot in principal components analyses. Overall, these studies suggest that priority in the standing tree has ‘downstream’ effects that can, over the long term and in varying environments, functionally change the consequences of decomposition.

1 - University of Minnesota, Bioproducts and Biosystems Engineering, 2004 Folwell Ave, St Paul, MN, 55108, USA
2 - University of Minnesota, BioTechnology Institute, St Paul, MN, 55108, USA

Keywords:
none specified

Presentation Type: Symposium or Colloquium Presentation
Session: SY4
Location: Auditorium/Kellogg Hotel and Conference Center
Date: Tuesday, June 10th, 2014
Time: 4:00 PM
Number: SY4007
Abstract ID:51
Candidate for Awards:None