中文摘要：

近几年随着有机农业的发展，丛枝菌根的作用受到特别关注。丛枝菌根是由植物根系与丛枝菌根真菌（AMF）形成的一种共生体。在植物-AMF-土壤系统中，AMF为植物提供N、P等营养的同时从根系得到所需的C。概述了植物-AMF-土壤系统中C、N、P等营养物质的交流以及AMF与土壤微生物的互作关系。丛枝菌根的形成可显著提高植物对P的吸收，且在高P条件下多余的P可储存于AMF中。AMF对土壤N循环的影响相当复杂，可能参与调控N循环的多个过程，如硝化作用、反硝化作用和氨氧化作用等。在有机质丰富的土壤中AMF菌丝可快速扩增并吸收其中的N，主要供菌丝自身所需，只有一小部分传递给植物。AMF对土壤C库的影响尚存争议，可能存在时间尺度的差异。短期内可活化土壤C，而在长期尺度上可能有利于土壤C的储存。AMF能够通过改变土壤微生物群落结构而影响植物-土壤体系的物质交流。AMF与解磷菌、根瘤菌和放线菌的协同增效作用可促进土壤有机质的降解或增强其固氮能力；AMF对氨氧化菌的抑制作用可降低氨的氧化减少N2O的释放。AMF与外生共生真菌EMF共存时，表现出协同增效作用，但EMF的优先定殖会限制AMF的侵染。AMF不同类群之间则主要表现为竞争和拮抗关系。AMF与土壤微生物之间的互作关系受土壤无机环境的影响，在养分亏缺条件下微生物之间往往表现为竞争关系。因植物、AMF与土壤微生物之间存在复杂的互作关系，为此AMF并不总是表现出其对植物营养的促进作用。目前关于AMF的作用机理仍以假说为主，需要进一步的实验验证。在植物-AMF-土壤系统中N与C的交流和P与C的交流并未表现出一致性，对N、P循环相互关系的进一步探讨有助于深入理解植物-土壤体系中的养分循环。植物、AMF和土壤微生物的养分来源及其对养分的相对需求强度和吸收效

英文摘要：

Arbuscular mycorrhizal symbioses （AM symbioses）, formed between Arbuscular mycorrhizal fungi （AMFs） and the majority （ca. 80%） of terrestrial plants, play an important part in the regulation of nutrient cycling in plant-soil systems. Owing to their potentially promising role in sustainable agriculture, AM symbioses have attracted increasing interest in the last decade. This review emphasized the functional interrelations among AM symbioses, soil free-living microbes, and the dynamics of carbon （C）, nitrogen （N）, and phosphorus （P） in plant-soil systems. The contribution of AM symbioses to plant P has become central to our understanding of AM symbiotic function over the past few decades. There is accumulating evidence that plant P uptake is bidirectionally regulated by AM symbioses. More specifically, plant P uptake is enhanced by AMF infection when the soil is P deficient, but when there is excessive soil P, its transfer to the plant is restricted and excessive P accumulates in hyphae, spores, or vessels. The ability of plants to take in P has been correlated with the volume of soil that their roots can explore. However, in the presence of AMF, mycorrhizal P uptake becomes the dominant pathway, even though plant growth or total P uptake may not be enhanced by the interaction. A benefit of AMF infection to plant P uptake is associated with carboxylate exudation produced by hyphae, which promote the mineralization and disaggregation of organic matter through enhancing the activities of phosphate-solubilizing bacteria. Comparatively, the effects of AMFs on N cycling are particularly complex since fungi are likely involved in all N processes. Arbuscular mycorrhizal fungi can take up both inorganic N and low-molecular-weight organic N from soil organic matter, which is primarily used by the fungus, with only a small amount being transferred to the roots. Arbuscular mycorrhizal fungi can also reduce N loss by regulating the trade-off between nitrification and denitrification, through reducing th