Diversity and effect of Trichoderma isolated from the roots of Pinus densiflora within the fairy ring of pine mushroom (Tricholoma matsutake)

Pine mushroom (PM, Tricholoma matsutake) is an important ectomycorrhizal fungus in Asia primarily due to its value as a food delicacy. Recent studies have shown that fairy rings of PM have distinctive fungal communities, which suggests that other fungi influence the growth of PM. Trichoderma is a well-known saprotrophic fungus commonly found in pine roots within PM fairy rings; however, little is known about the diversity of Trichoderma associated with PM and how these species influence PM growth. This study focused on diversity of Trichoderma isolated from pine roots within PM fairy rings and how these species affect the growth of PM isolate. Based on tef1a phylogenetic analyses, nine Trichoderma species (261 isolates) were identified. Trichoderma songyi and T. spirale were the dominant species, and Trichoderma community varied geographically. Growth experiments indicated that metabolites from five Trichoderma species had a significant influence on the growth of PM isolates. Metabolites of two Trichoderma species increased PM growth, while those of three Trichoderma species suppressed the growth. Within the fairy rings, Trichoderma that had a positive or neutral effect comprised the majority of Trichoderma communities. The results of this study suggest that various Trichoderma species co-exist within PM fairy rings and that these species influence PM growth.