Role of arbuscular mycorrhizal fungi behind the plant ameliorated tolerance against cadmium stress: A global meta-analysis

Increasing industrial activity has led to a growing risk of cadmium (Cd) accumulations and biomagnifications in plants and humans. Arbuscular mycorrhizal fungi (AMF) have been extensively studied as a soil amendment technique due to their capability to reduce the accumulation of Cd in plant tissues. However, a quantitative and data-based consensus has yet to be reached on the effect of AMF on host plant growth, Cd uptake, and tolerance. Here, a meta-analysis was conducted to quantitatively evaluate the impact of AMF using 2079 individual observations from 157 articles. The research showed that adding AMF to the plants stopped the accumulation of Cd in the shoots and roots and increased biomass, phosphorus (P), and catalase (CAT) in the leaves compared to the control. Yet these effects varied with different mycorrhizal colonization rates, AMF species, plant families and functional types, and soil Cd contents. Mycorrhizal colonization rates positively correlate with changes in biomass and P content in shoots and roots, and CAT and proline in leaves, while showing no significant correlation with Cd concentration in plant tissues. Plants inoculated with Funneliformis caledonium exhibited greater biomass accumulation, while those inoculated with Rhizophagus irregularis showed higher P uptake. Mycorrhizal Legumes demonstrated the most significant reduction in Cd concentration among the plant families, whereas Compositae exhibited the highest increase in biomass, P content, and CAT. In addition, soils with intermediate and high Cd levels were more favorable for AMF to promote plant biomass accumulation. This study shows that AMF can help plants become more resistant to environments with excessive Cd. It also talks about how to manage and use them as bio-inoculants for farming and environmental restoration. Acknowledgments This research received funding from the National Key Research and Development Program of China (No. 2022YFC3701303) and the National Natural Science Foundation of China (Grant Nos. U2344228).