Mycorrhizal Fungi: Research Advances, Applications, and Future Perspectives

Mycorrhizae are symbiotic associations between most terrestrial plants and certain groups of fungi, occurring in over 90% of plant species and across nearly all terrestrial ecosystems. In this mutualism, plants provide carbon to fungi, which, in return, supply soil-derived nutrients and confer additional benefits, such as enhanced growth and reduced susceptibility to environmental stresses like drought and salinity. The main types of mycorrhizae are arbuscular mycorrhizae (AM), ectomycorrhizae, ectendomycorrhizae, arbutoid, monotropoid, orchid mycorrhizae, and ericoid mycorrhizae. Advances in the study of the hyphosphere microbiome have clarified the role of fungal hyphae in soil processes and global carbon cycling, with estimates suggesting that nearly one-third of annual fossil fuel CO₂ emissions are directed to mycelial biomass. Mycorrhizal fungi are increasingly studied as bioprotectors, improving crop growth in degraded soils by enhancing water and nutrient uptake, reducing the need for chemical fertilizers, and activating plant defense mechanisms. In the context of climate change, especially with more frequent droughts, AM fungi can help mitigate water stress in crops. Molecular biology tools have revealed thousands of previously undetectable mycorrhizal fungi species, many of which show low host specificity and can be associated with diverse plant species. This has stimulated interest in artificial mycorrhizae, though these lack the resilience of natural systems under abiotic stress and disease. Therefore, they are better suited to complement natural associations or be applied in systems where crops do not naturally form mycorrhizae, contributing to sustainable agriculture and carbon sequestration.