Competition between two wood-degrading fungi with distinct influences on residues

Abstract

Many wood-degrading fungi colonize specific types of forest trees, but often lack wood specificity in pure culture. This suggests that wood type affects competition among fungi and indirectly influences the soil residues generated. While assessing wood residues is an established science, linking this information to dominant fungal colonizers has proven to be difficult. In the studies presented here, we used isolate-specific quantitative PCR to quantify competitive success between two distinct fungi, Gloeophyllum trabeum and Irpex lacteus, brown and white rot fungi, respectively, colonizing three wood types (birch, pine, oak). Ergosterol (fungal biomass), fungal species-specific DNA copy numbers, mass loss, pH, carbon fractions, and alkali solubility were determined 3 and 8 weeks postinoculation from replicate wood sections. Quantitative PCR analyses indicated that I. lacteus consistently outcompeted G. trabeum, by several orders of magnitude, on all wood types. Consequently, wood residues exhibited distinct characteristics of white rot. Our results show that competitive interactions between fungal species can influence colonization success, and that this can have significant consequences on the outcomes of wood decomposition.

Initial white rot type dominance of wood decomposition and its functional consequences in a regenerating tropical dry forest

“…Wooddegrading fungi, for example, may cause white rot (extensive lignin removed with carbohydrates) while others cause brown rot (modest lignin removal) (Eriksson et al, 1990), and these rot types vary along a spectrum of lignin selectivity as decomposition proceeds (Worrall et al, 1997;Riley et al, 2014). Decomposer nutritional modes affect CO 2 evolution and organic inputs to the soil (Berg and McClaugherty, 2008), as well as carbon content, metalbinding, redox, permeability, and sorption in resulting residues (Ryp a cek and Ryp a ckov a, 1975; Gilbertson, 1980;Jurgensen et al, 1997;Filley et al, 2002;Song et al, 2012;Harmon et al, 2013). Fungal mycelial networks further connect above-with belowground pools and create an avenue for element translocation into and out of deadwood (Ostrofsky et al, 1997;Boddy, 1999;Connolly et al, 1999;Liew and Schilling, 2012).…”

“…This opportunity to defend wood volume favors priority effects among colonizers (Boddy, 2000;Fukami et al, 2010) including the earliest infections of standing trees as endophytes (Boddy, 2001;Parfitt et al, 2010;Rodríguez et al, 2011). Because decomposers employ functionally distinct mechanisms to deconstruct wood (Eriksson et al, 1990;Riley et al, 2014), the community structure among wood colonizers can significantly alter the overall decomposition rate (Fukami et al, 2010;Dickie et al, 2012;Song et al, 2012;van der Wal et al, 2015).…”

Enzymatic Strategies and Carbon Use Efficiency of a Litter-Decomposing Fungus Grown on Maize Leaves, Stems, and Roots

“…Although determining the CUE of individual microbial species is necessary, it is not feasible to perform in situ , which was recently highlighted by Geyer et al (2016). Some studies have been conducted on individual species growing on plant litters, but these did not report the microbial biosynthesis and respiration data required to calculate CUE or did not explicitly calculate this parameter (e.g., Boberg et al, 2008; Allison et al, 2009; Song et al, 2012). These laboratory microcosm approaches with individual species can capture the drivers of the microbial metabolism of a population, including growth respiration and cellular maintenance, as proposed by Geyer et al (2016).…”

Fungal Traits That Drive Ecosystem Dynamics on Land

“…For example, it can release cellulose from its physical and chemical protections by lignin (70,236) and then immediately break down and acquire the cellulose before "cheater" fungi can exploit it (237). In fact, fungi that can target lignin as well as cellulose often outcompete fungi that target cellulose alone (238,239).…”