Claroideoglomus etunicatum affects the diversity and composition of the rhizosphere microbial community to help tall fescue resist saline–alkali stress

Introduction: Arbuscular mycorrhizal fungi (AMF) and plant rhizosphere microbes reportedly enhance plant tolerance to abiotic stresses and promote plant growth in contaminated soils. Soil salinization represents a severe environmental problem. Although the influence of AMF in the phytoremediation of saline-alkali soils has been fully demonstrated, the underlying interactive mechanisms between AMF and rhizosphere microbes are still unclear. Methods: ) on tall fescue growth promotion and the rhizosphere microbial community in saline-alkali soils. We aimed to investigate the mechanism of AMF affecting plant growth under saline-alkali stress conditions via interactions with rhizosphere microbes. Results: We found that AMF significantly increased plant shoot, root, and total biomass in saline-alkali stress soil. AMF significantly increased the diversity of bacterial and fungal communities and altered their composition. For bacteria, the AMF inoculation treatment (M+) showed higher relative abundance of Proteobacteria, Actinobacteriota, and Firmicutes and lower relative abundance of Acidobacteriota and Chloroflexi compared to the no-AMF application treatment (M-). For fungi, the M+ treatment showed lower relative abundance of Ascomycota and higher relative abundance of Mortierellomycota compared to the M- treatment. Furthermore, structural equation modeling (SEM) revealed that AMF promoted plant growth under saline-alkali stress conditions mainly by regulating the diversity of bacterial communities in the rhizosphere soil. Discussion: This study provides a theoretical basis for improving plant adaptation to saline-alkali stress through soil microbial management practices.