Recent advances in the defense mechanisms of arbuscular mycorrhizal fungi in antibiotic-contaminated soil ecosystems.

Arbuscular mycorrhizal fungi (AMF) are important soil symbionts that support plant nutrient acquisition, stress tolerance, and soil ecosystem stability. The increasing accumulation of antibiotic residues in agricultural soils may inhibit AMF spore germination, hyphal development, and root colonization, thereby weakening mycorrhizal functions and plant-soil feedback. This review summarizes recent advances in AMF responses to antibiotic stress in soil ecosystems and proposes a five-layer defense framework: external interfacial barriers, intracellular metabolic detoxification, antioxidant defense system activation, molecular regulation, and symbiont-level cooperative defense. We emphasize that the evidentiary strength supporting these mechanisms varies across different validation levels. Some responses, such as changes in colonization, hyphal growth, antioxidant enzyme activity, and rhizosphere or hyphosphere microbial communities, have been experimentally observed in antibiotic-contaminated systems. By contrast, several intracellular detoxification and regulatory processes, including pathways mediated by cytochrome P450s (P450s), glutathione S-transferases (GSTs), UDP-glycosyltransferases (UGTs), and transporters, remain primarily inferred from AMF genomic resources, host-symbiont studies, and fungal or plant xenobiotic metabolism studies. Current research is still limited by short-term experimental designs, a strong focus on tetracycline, insufficient molecular validation, and a lack of predictive models. Future studies should integrate multi-omics, single-cell approaches, and artificial intelligence-assisted modelling to identify key functional genes, distinguish direct AMF responses from host- or microbiome-mediated effects, and improve the application of AMF in sustainable remediation of antibiotic-contaminated soils.