Effect of global change factors on AM fungi
Most GCF treatments decreased AM fungal root colonization except inoculation R. irregularis under microplastic treatment (Figure S2d). Multiple GCFs treatment caused a 72.38% reduction in mycorrhizal colonization (p < 0.001, Table S2, Figure S2a). The soil hyphal length density (HLD) in high AMF diversity treatment was higher than that in low AMF diversity under the same GCF condition, except in case of saline-alkali stress (p < 0.001, Table S2, Figure S2b). Most GCF treatments declined HLD, but drought enhanced HLD when inoculated with G. etunicatum (p < 0.001) and in mixed inoculation scenarios (p < 0.05, Figure S2e). A slight increase in HLD was also observed with R. irregularis under antibiotic stress and withG. etunicatum under microplastic stress (Figure S2e). GCFs treatment significantly affected AMF spore density (p < 0.001, Table S2, Figure S2c), while the response of each AMF inoculation differed (Figure S2f). The negative impact of multiple GCFs on spore density in high AM fungal diversity treatment was significantly greater than that in single GCF treatments (p < 0.001, Figure S2f).
In our findings, we observed that soil saline-alkali stress exerted a significantly greater negative effect on AM fungi compared to the other five GCFs, except when considering multiple GCFs. Regression analysis showed that soil pH was negatively correlated with plant root mycorrhizal colonization, HLD, and spore density, notably, these correlations exhibited steeper slopes with high AMF diversity treatment than low AMF diversity (p < 0.05, Figure S3).