Arbuscular mycorrhizal fungi as mediators of nitrogen, phosphorus, and carbon: implications for plant growth and development

Arbuscular mycorrhizal (AM) fungi are essential members of the plant microbiome, exerting a profound influence on nutrient acquisition, and efficiency. While their role in facilitating phosphorus (P) uptake is well established, the broader contributions of AM fungi to nitrogen (N), P, and carbon (C), and the subsequent impacts on plant growth and development, remain comparatively underexplored. This review synthesizes recent advances in understanding AM symbiosis, highlighting its importance in regulating nutrient fluxes and plant physiological processes. AM fungi secrete glomalin-related soil proteins that improve soil aggregation and foster favorable conditions for microbial communities involved in nutrient transformations. In association with nitrogen-fixing bacteria, AM fungi contribute to improved N availability, providing up to 30% of the plant’s N demand. This supports amino acid biosynthesis and fundamental physiological processes, such as photosynthesis and production of metabolites, thereby promoting plant growth. Through the mycorrhizal pathway (MP), plants may acquire up to 80% of their P requirements, an important advantage during early plant’s developmental stages. In return, host plants allocate 20-40% of their photosynthetically derived C to sustain the fungal partner. Beyond individual nutrient exchanges, AM fungi play a pivotal role in regulating the stoichiometry of C:N:P in plant–fungal symbioses, with cascading effects on plant nutrition, soil fertility, and ecosystem functioning. By mediating these nutrient interactions, AM fungi not only support plant growth and development but also influence broader biogeochemical cycles. This review underscores the pivotal role of AM fungi in nutrient dynamics and provides insights to guide future research on mycorrhizal associations with nutrients and sustainable plant growth and development.