外生菌根真菌的共生互作和宿主选择机制研究进展
Research progress on symbiotic interaction and host selection mechanisms of ectomycorrhizal fungi
A，B：预共生阶段. C，D：共生阶段. A：植物通过根系分泌物招募潜在的共生伙伴，真菌分泌LCO表明自己的敌友身份. 植物根系分泌物加强真菌孢子萌发和菌丝趋向性;真菌分泌植物激素引发植物侧根生长，真菌分泌的LCO激活被子植物的CSSP. B：植物继续分泌化感物质招募真菌，真菌接近根系后通过分泌多种信号分子确认宿主精确身份如凝集素、MiSSP等. C：菌丝鞘的形成. 凝集素、疏水蛋白等引导菌丝在根表层聚集，同时分泌植物细胞壁降解酶如GH5、GH28对细胞壁进行重塑. D：哈氏网的形成. 对细胞壁的降解扩大了非原质体空间，菌丝在根皮层生长形成哈氏网，哈氏网扩大了与植物的营养交换界面，远端外延菌丝吸收的N、P等营养通过液泡运输至哈氏网，再通过转运蛋白等方法释放至共生界面
A, B: Pre-symbiotic stage. C, D: Symbiotic stage. A: Plants recruit potential symbiotic partners through root exudates, and fungi secrete LCO to show their identity as friends or enemies. Plant root exudates enhanced fungal spore germination and mycelial tendency, and fungi secrete phytohormones to induce lateral root growth. The LCO secreted by fungi activates the CSSP of angiosperms. B: Plants continue to secrete allelochemicals to recruit fungi. When fungi approach the root, they secrete a variety of signaling molecules to confirm the precise identity of the host such as lectin, MiSSP, etc. C: The formation of hyphal mantle. Lectin, hydrophobins and so on lead hyphae to gather on the surface of roots and plant cell wall degrading enzymes are secreted to remodel the cell wall, such as GH5, GH28. D: The formation of Hartig net. The degradation of cell wall enlarges the apoplast space; the hyphae grow in the root cortex and form Hartig net. Hartig net expands the interface of nutrient exchange with plants, extension hyphae absorb nutrients such as N and P in the distance and transport by vacuole to Hartig net, and then released to the symbiotic interface by transporters and other methods.
