Successional Change of the Fungal Microbiome Pine Seedling Roots Inoculated With .

The pine mushroom (; Agaricales, Tricholomataceae) is an ectomycorrhizal fungus that produces a commercially valuable, edible mushrooms. Attempts to artificially cultivate has so far been unsuccessful. One method used to induce to produce fruiting bodies of in the wild is shiro (mycelial aggregations of ) transplantation. ectomycorrhization of with seedlings of has been successful, but field trials showed limited production of fruiting bodies. Few studies have been done to test what happens after transplantation in the wild, whether persists on the pine seedling roots or gets replaced by other fungi. Here, we investigated the composition and the interaction of the root fungal microbiome of seedlings inoculated with over a 3 year period after field transplantation, using high-throughput sequencing. We found a decline of colonization on pine roots and succession of mycorrhizal fungi as seedlings grew. Early on, roots were colonized by fast-growing, saprotrophic Ascomycota, then later replaced by early stage ectomycorrhiza such as . At the end, more competitive species dominated the host roots. Most of the major OTUs had negative or neutral correlation with , but several saprotrophic/plant pathogenic/mycoparasitic species in genera , , and had positive correlation with . Four keystone species were identified during succession; two species (, and ) had a positive correlation with , while the other two had a negative correlation (, ). These findings have important implications for further studies on the artificial cultivation of .