Table 1.

The 10 most common fungal OTUs in roots

OTU ID	No. obs	Phylum	Class	Order	Family	Genus1	Habitat specificity (root vs. soil)	Host specificity (d')	BLAST accession	Description	E-value	Identity (%)
483	63	Ascomycota	Leotiomycetes	Helotiales			Root	0.027	GU166474.1	Helotiales sp.	6E-142	96
577	48	Ascomycota	Eurotiomycetes	Chaetothyriales	Herpotrichiellaceae		Root	0.036	HM803232.1	Cladophialophora carrionii	2E-137	93
257	34	Ascomycota	Leotiomycetes	Helotiales			Root	0.098	HM190132.1	Ascomycota sp.	3E-160	100
499	31	Ascomycota	Leotiomycetes	Rhytismatales			Root	0.063	GU138714.1	Lophodermium jiangnanense	1E-68	83
263	28	Basidiomycota	Agaricomycetes	Russulales	Russulaceae	Russula	Both habitats	0.032	AB597671.1	Fungal sp.	3E-174	97
289	19	Basidiomycota	Agaricomycetes	Russulales	Russulaceae	Lactarius2	Both habitats	0.1731	AB597656.1	Fungal sp.	0	100
255	18	Ascomycota	Leotiomycetes	Helotiales			Too rare3	0.095	AF081443.2	Mycorrhizal sp.	3E-159	99
247	17	Ascomycota	Leotiomycetes	Helotiales	Dermateaceae		Too rare3	0.124	JN607229.2	Fungal sp.	2E-161	100
281	8	Ascomycota	Eurotiomycetes	Chaetothyriales	Herpotrichiellaceae		Too rare3	0.025	GQ996076.1	Fungal sp.	3E-169	98
301	8	Ascomycota	Leotiomycetes	Rhytismatales			Too rare3	0.285	FR837916.1	Rhytismataceae sp.	6E-112	91

Frequently observed fungal OTUs are listed in terms of the number of observations in 159 root samples. Number of links to plants, the result of CLAM test (Fig. 3), and d' measure of specificity to host plants are shown. Detailed identification of the ascomycete OTUs was performed based on a phylogenetic analysis (Fig. S1). The results of normal BLAST search are also shown with E-values and maximum identity scores.

¹Significantly high specificity to host plants (P < 0.05).

²Taxonomic information was assigned at species level (Lactarius quietus).

³Fungus detected only from root samples; habitat specificity was not assigned by CLAM test due to a small number of observations (Fig. 3).