矿物风化与食用性菌根真菌共生策略与可持续性研究进展

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

外生菌根(ectomycorrhizal,ECM)真菌是一类能够与植物形成外生菌根结构的真菌,是连接地上共生植物与地下生态系统的重要纽带,其中很多种类是营养美味的食用真菌。ECM真菌能促进植物对矿质营养,特别是限制性的磷等矿质元素的吸收,进而促进植物生长。一般认为,ECM真菌对土壤矿质营养的获取主要是通过其对土壤中难降解性矿物的风化作用,但风化过程与机制尚不清楚。通过野外考察、菌种分离和实验条件下的风化实验研究,发现很多ECM真菌不能通过上调小分子有机酸合成来风化矿物,显示出较弱的矿物风化能力,特别是不能独自利用磷灰石中的磷元素。结合生物组学技术研究,发现在森林土壤中,某些风化能力较弱的ECM真菌能通过富集矿物风化细菌来促进矿物溶解,并通过自身的高亲和性离子转运系统吸收溶出的矿质营养来供应宿主植物。此外,ECM真菌还能富集特殊的多功能性草酸盐降解菌(如兼具固氮和促进菌根形成作用)来消除过量草酸盐对矿物风化与营养吸收产生的障碍。研究证实,ECM真菌能够调控植物根际微生物群落结构,促进“植物-真菌-细菌”之间互惠协作关系,从而维持健康、可持续的森林生态系统。本文主要从矿物风化的角度分析ECM真菌的共生策略,提出增加林地ECM真菌产量和促进林地生态系统可持续性的新思路,并对该领域的未来研究方向进行展望。

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.