丛枝菌根真菌形态结构、物种多样性和群落组成对氮沉降响应研究进展

工业革命以来，人类活动输入到生态系统中的氮迅速增加，已突破地球所能承受的氮循环阈值。过量氮沉降会造成生物多样性丧失等一系列危害，严重影响生态系统结构和功能。丛枝菌根(AM)真菌能够与大约70%-80%的陆地植物种类形成共生关系，在宿主植物养分吸收、抵抗外界不良环境压力、群落动态和物种共存、生物地球化学循环等方面具有重要的作用。探究AM真菌对氮沉降的响应对认识和把握菌根真菌缓解氮沉降的负面后果，维持生态系统的结构和功能具有重要意义。本文综述了AM真菌的形态结构、物种多样性和群落组成等对氮沉降的响应机制。前人研究表明氮沉降通常降低AM真菌的根系定殖率，减少根外菌丝密度和土壤孢子密度，改变菌丝生长的时间动态;降低AM真菌多样性，改变AM真菌群落组成。氮沉降主要通过缓解植物氮限制、降低植物对菌根的依赖性、减少植物对菌根的碳分配、改变根系和土壤中菌根生物量比率、在植物根内维持稳定的菌根真菌组成作为应对未来扰动的“保险”、改变土壤资源有效性及土壤酸度等直接和间接途径影响AM真菌结构和功能。我们建议在未来研究中整合多组学手段、开展学科交叉，聚焦复杂的生物互作体系对氮沉降的响应机制，以及AM真菌对氮沉降响应的生态后果。

Research progress on the responses of morphological structure,species diversity and community composition of arbuscular mycorrhizal fungi to nitrogen deposition

Since industrial revolution, ecosystems have received a vast amount of nitrogen from anthropogenic activities beyond the earth’s nitrogen cycling threshold. Excessive nitrogen deposition severely threatens biodiversity and ecosystem structure, stability, and functioning. Arbuscular mycorrhizal (AM) fungi, as the symbiosis partners of ca. 70%-80% of terrestrial plant species, are essential for plant’s nutrient absorption and stress resistance. Thereby, AM fungi play a crucial role in biogeochemical cycles, plant community dynamics, and species co-existence. Research on the response of AM fungi to nitrogen deposition is essential for understanding and harnessing the roles of AM fungi in mitigating the adverse effects of nitrogen deposition of ecosystem structure and function. The recent progress of the responses of AM fungi to nitrogen deposition is herein reviewed, in terms of morphological structure, species diversity, and community composition. In general, nitrogen deposition reduces AM fungal intra-radical colonization, extra-radical hyphal density, spore density, and taxon diversity, and changes AM fungal community composition. The observed changes likely resulted from the combined effects of several inter-dependent pathways, i.e., alleviation of plant’s nitrogen limitation, reduction of mycorrhizal dependence, and alteration of carbon and biomass allocation. We suggest blending multi-omic tools, focusing on the response of biotic interaction to nitrogen deposition and the consequences to ecosystems of AM fungi in response to nitrogen deposition in future interdisciplinary research.