Fig. 2 Phylogeny and LEfSe discrimination
Indicator taxa
The fungal community indicator taxa of nonrhizosphere and rhizosphere soils of A. spinulosa were significantly different at different taxonomic levels, with a large proportion of indicator taxa being unclassified soil fungi (Table 1). At the phylum level, 12 rhizosphere indicator taxa with IndVal values of 0.24–0.57 were observed, with the obvious indicator taxon being Chytridiomycota (IndVal = 56.67%). Twelve nonrhizosphere indicator taxa with IndVal values of 0.25–0.53 were also observed at the phylum level, with the obvious indicator taxon being Glomeromycota (IndVal = 52.71%). Only one indicator taxon—Basidiomycota—was common between inter- and nonrhizosphere soils.
At the order level, 84 rhizosphere indicator taxa with IndVal values of 0.21–0.63 were observed, with the obvious indicator taxon being Chantharellales (IndVal = 63.40%). In total, 79 nonrhizosphere indicator taxa with IndVal values of 0.21–0.67 were observed, with the obvious indicator taxon being Orbiliales (IndVal = 67.43%).
At the family level, 154 rhizosphere indicator taxa with IndVal values of 0.21–0.66 were observed, with the obvious indicator taxon being Ceratobasidiaceae (IndVal = 66.43%). Further, 156 nonrhizosphere indicator taxa with IndVal values of 0.20–0.68 were noted, with the obvious indicator taxon being Cordycipitaceae (IndVal = 67.61%).
At the genera level, 241 rhizosphere indicator taxa with IndVal values of 0.20–0.67 were observed, with the obvious indicator taxon being the genus Tolypocladium (IndVal = 59.83%). In total, 250 nonrhizosphere indicator taxa with IndVal values of 0.20–0.69 were observed, with the obvious indicator taxon being the genusAgaricus (IndVal = 69.12%).
At the species level, 241 rhizosphere indicator taxa with IndVal values of 0.20–0.87 were observed, with the obvious indicator taxa being unclassified species of the genera Ciliolarina andSerendipita ; both genera had an IndVal value of 86.96%. In total, 283 nonrhizosphere indicator taxa with IndVal values of 0.20–0.91 were observed, with the obvious indicator taxa beingSaitozyma ninhbinhensis and Virgatospora echinofibrosa ; both had an IndVal value of 91.30%.
The number of habitat-indicating taxa in the soil fungal community ofA. spinulosa was lower at three taxonomic levels, namely, order, family, and genus, than at the nonrhizosphere level. The characteristic indicator taxa were represented only at the species level, with 3 species of soil fungi being characteristic of the A. spinulosarhizosphere and 24 species of soil fungi being characteristic of the nonrhizosphere.
The difference in indicator taxa indicates that soil fungal communities have obvious indicator effects on A. spinulosa roots. The unclassified taxa with indicator effects on the A. spinulosarhizosphere soil may be crucial taxa reflecting the soil environmental changes. However, this finding needs to be explored in future research.
Table 1 Indicative values for soil fungal taxa of A. spinulosa at different taxonomic levels