Different arbuscular mycorrhizal fungi alleviate aluminum-induced metabolic disruption and promote loquat growth

Loquat ( Eriobotrya japonica ) productivity is severely constrained by acidic soils due to aluminum (Al) toxicity. Although arbuscular mycorrhizal fungi (AMF) can alleviate Al stress, the species-specific mechanisms remain unclear. This study compared three AMF species: Rhizophagus irregularis (Ri), Glomus versiforme (Gv), Funneliformis mosseae (Fm), as well as a synthetic community (Mix) in mitigating Al toxicity in loquat seedlings. AMF inoculation enhanced root architecture and increased Ca and Mg uptake, effectively alleviating the growth-inhibitory effects of Al. Metabolomic analyses identified 95 shared metabolites mainly involved in amino acid and purine metabolism, and revealed that AMF modulated the tricarboxylic acid (TCA) cycle, increasing endogenous organic acid accumulation while reducing rhizosphere exudation, thereby mitigating Al toxicity. Notably, different AMF species exhibited distinct metabolic pathway strategies. Ri primarily promoted plant growth and promoted Al retention in roots; Gv stimulated carbohydrate metabolism and phloem transport, facilitating Al translocation and providing carbon skeletons for organic acid biosynthesis; and Fm reprogrammed lipid metabolism, maintaining membrane integrity and supporting fungal colonization. These findings reveal the species-specific interactions between AMF and loquat under Al stress and provide a mechanistic basis for targeted AMF inoculation to loquat productivity on acidic soils. • Different AMF species exhibit distinct effects on loquat under aluminum stress. • AMF improve aluminum tolerance via regulation of specific metabolic pathways. • Ri enhances energy utilization, Gv regulates sugar synthesis and transport; Fm stabilizes cell membranes. • AMF alleviate Al toxicity by promoting organic acid accumulation and reducing rhizosphere exudation. • Findings support the use of AMF for phytoremediation of Al-contaminated soils.