Symbiotic Strategies and Sustainability of Edible Mycorrhizal Fungi: From the Perspective of Mineral Weathering

Ectomycorrhizal (ECM) fungi, which can form ectomycorrhiza with plants, are an important link between the above-ground symbiotic plants and the subsurface ecosystems, and many of them are nutritious and delicious food. ECM fungi promote the absorption of mineral nutrients by plants, especially for limiting mineral elements such as phosphorus, thereby improving the growth of plants. It is generally believed that ECM fungi acquire mineral nutrients from soil mainly through their weathering effect on soil minerals that are difficult to degrade, but the weathering process and mechanisms are still not clear. Through field investigation, strain isolation and weathering tests, it is found that many ECM fungi cannot weather minerals by up-regulating the synthesis of small molecular organic acids, showing a weak ability to weather mineral. Particularly, they cannot use phosphorus in apatite independently. Bio-omics studies find that in forest soils, some ECM fungi with weaker weathering ability can promote the dissolution of minerals by enrichment of mineral-weathering bacteria, and absorb dissolved mineral nutrients to supply host plants through their high-affinity ion transport systems. In addition, ECM fungi can enrich special versatile oxalate-degrading bacteria (such as those that have the capability of nitrogen fixation and promoting mycorrhizal formation) to eliminate the inhibitory effect of excess oxalate on mineral weathering and nutrient absorption. It has been confirmed that ECM fungi can regulate the rhizosphere microbial community structure and promote the mutually cooperative relationship among plants, fungi and bacteria to maintain a healthy and sustainable forest ecosystem. This paper reviews the symbiotic strategies of ECM fungi from the perspective of mineral weathering, puts forward new ideas for increasing the biomass of edible fungi in woodlands and promoting the sustainability of woodland ecosystems, and gives an outlook on future research directions in this field.