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

Abstract

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. A greenhouse pot experiment was conducted to explore the effects of AMF (Claroideoglomus etunicatum) on tall fescue growth promotion and 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. We found that AMF significantly increased plant shoot, root and total biomass in the saline-alkali stress soil. AMF significantly increased the diversity of bacterial and fungal communities, and altered their composition: for bacteria, AMF inoculation treatment (M+) had higher relative abundance of Proteobacteria, Actinobacteriota and Firmicutes, and lower relative abundance of Acidobacteriota and Chloroflexi than no AMF application treatment (M-); for fungi, M + treatment had lower relative abundance of Ascomycota and higher relative abundance of Mortierellomycota than M- treatment. Furthermore, structural equation modeling (SEM) revealed that AMF promoted plant growth under saline-alkali stress conditions mainly by regulating plant rhizosphere soil bacterial communities. This study provides a theoretical basis for improving plant adaptation to saline-alkali stress through soil microbial management practices.