Arbuscular mycorrhizal fungi alter microbiome structure of rhizosphere soil to enhance Festuca elata tolerance to Cd

Abstract

The remediation of heavy metal cadmium (Cd) contaminated soil has attracted much attention. Arbuscular mycorrhiza (AM) fungi combined with phytoremediation is an efficient, economical and environmentally friendly remediation strategy. However, it is not clear the regulation of AM fungi on Cd stress by altering microbiome structure of rhizosphere soil. Here, Funneliformis mosseae was inoculated to determine the Festuca elata growth indexes, organic acids secreted by roots, Cd uptake, and rhizosphere microbial community in soil cultivation. The results showed that under Cd stress, AM fungi promoted the plant growth compared with no inoculation group. Cd contents in shoot and root cell wall increased by 20.63 %, and 16.66 %, respectively. The activities of soil saccharase and urease, and the absorption capacity of nitrogen were significantly increased upon AM fungi symbiosis. Meanwhile, AM fungal symbiosis promoted the secretion of organic acids from plant roots, reduced rhizosphere soil pH, and significantly increased the concentration of DTPA Cd in soil. Furthermore, AM fungi increased the relative abundance of beneficial rhizosphere bacteria (Actinobacteriota, Chloroflexi and Proteobacteria), which could resistant the heavy metals stress and promote plant growth. Correlation analysis showed that total organic acid content was significantly positively correlated with Myxococcota, Chloroflexi and Glomeromycota. It is suggesting that AM fungi could enhance the resistance to Cd stress in F. elata by altering the rhizosphere microbial community. These findings provide insights into the effects of AM fungi on plants growth and rhizosphere microorganisms under Cd stress, and provides theoretical basis to further improve Cd-contaminated soil phytoremediation.