丛枝菌根生态生理与应用技术研究展望

Research Prospects on Ecology, Physiology and Application Technology of Arbuscular Mycorrhizal Fungi

摘要

<正>丛枝菌根（AM）真菌是最具代表性的植物共生真菌，能够和70%以上的陆地植物形成共生体系。AM真菌从宿主植物获取碳源，同时帮助植物从土壤中吸收矿质养分和水分。大量研究表明，AM共生体系能够增强宿主植物对各种逆境胁迫的适应能力，与其他土壤有益微生物（如固氮菌、解磷菌等）协同作用，调控植物生长和生理变化。由于AM真菌不具有严格宿主专一性，其可在不同植物根系之间建立菌丝连接，并通过根外菌丝网络实现不同植物间的资源再分配，从而维持植物群落结构及功能的稳定。

丛枝菌根（AM）真菌是最具代表性的植物共生真菌，能够和70%以上的陆地植物形成共生体系。AM真菌从宿主植物获取碳源，同时帮助植物从土壤中吸收矿质养分和水分。大量研究表明，AM共生体系能够增强宿主植物对各种逆境胁迫的适应能力，与其他土壤有益微生物（如固氮菌、解磷菌等）协同作用，调控植物生长和生理变化。由于AM真菌不具有严格宿主专一性，其可在不同植物根系之间建立菌丝连接，并通过根外菌丝网络实现不同植物间的资源再分配，从而维持植物群落结构及功能的稳定。在生态系统水平，AM真菌深刻参与物质循环，调节生态系统对环境变化的响应。由于AM真菌具有重要的生态价值，AM真菌逆境生理和生态学研究已成为植物学、生态学和土壤学领域的热点，同时菌根应用技术在农业生产和环境保护，尤其是退化土壤修复中的应用也得到越来越多的关注。

得益于相关研究技术的发展和菌根研究者的不懈努力，近年来AM真菌生态和生理研究得以快速进展，尤其在AM共生体系建成和发育的分子机制，AM共生体系适应环境胁迫的生理机制，菌丝际微生物互作，以及AM真菌多样性地理分布及其对气候变化的响应等方面取得了重大突破，这也为菌根技术的发展和应用奠定了科学基础。基于学科发展趋势和应用需求分析，未来AM真菌生态生理和应用技术有望在以下几方面得到更为系统且深入的研究：

（1）AM共生的分子机制。随着基因组学、蛋白质组学和分子生物学技术的日益成熟，AM共生体系建成及调控的分子机制已取得突破进展，这也使得AM真菌纯培养技术得以有了重要进展，为AM真菌生理学研究及应用奠定了基础。然而，AM共生体系建成过程中的信号识别与转导机制目前尚不完全明晰，还需要利用多组学、生物化学等技术进一步明确共生体建成过程中的信号传递途径，以及共生体形成和维持过程中共生结构的发育、周转与调控机制。深入研究AM共生的分子机理与信号途径，对于揭示生命共生机制具有重大科学意义，同时可以进一步支撑菌根共生调控技术及AM真菌纯培养技术体系的发展。

（2）AM真菌生态功能及其调控。AM真菌生态学研究的最终目的是实现AM真菌的生态应用，为解决生态环境问题提供可选择的技术方案。这就要求菌根生态学研究不能局限于单纯的多样性研究，而需要和重大生态环境问题（如全球变化、生态退化等）结合起来，为减缓环境变化带来的负面影响及恢复退化的生态系统提供解决方案。近年来，不少研究者借助定位生态试验，考察了AM真菌群落对环境变化或人类干扰的响应，但很少有研究真正考虑AM真菌在生态系统适应和反馈调节环境变化中的潜在作用，即AM真菌的生态功能。基于AM共生体系对于植物适应各种逆境胁迫的重要作用，AM真菌在响应环境变化的同时，可能直接调控植物群落对环境变化的响应，减缓环境变化负面生态效应并驱动生态恢复过程。然而，目前既缺乏对AM真菌生态功能的科学评估，更缺乏有效的功能调控途径。基于此，迫切需要开展原位生态试验，通过对AM真菌群落的定向调控，系统研究AM真菌和植物群落对环境变化的协同响应及反馈调节机制，探讨AM真菌驱动生态恢复的效能和调控途径，为推动AM真菌生态应用奠定理论和方法基础。

（3）AM真菌应用技术体系。利用AM真菌等根际有益微生物构建功能菌群增强植物抗逆性的方法是一种基于自然的生态恢复方案，具有巨大的应用潜力。然而，菌根应用技术并非只是生产菌剂并对目标植物进行简单接种。在开放的自然环境中，接种的有效性受到多种因素（尤其是土壤环境和生物相互作用）的影响而难以预测。为了应对这一挑战，需要在考虑生态系统整体性的基础上，构建菌根应用技术体系，为作物生产或生态修复提供系统解决方案。首先，需要评估AM真菌接种的必要性，构建模型预测接种成效。其次，需要适应不同的应用情形，筛选出适用的菌株，提供合适的菌剂剂型，同时研究最适接种技术。为确保接种能够成功，还需要研发配套的土壤调控技术，针对性消减土壤障碍因子以确保AM真菌能够成功定殖并发挥功能。AM真菌与土壤微生物组的生物相互作用需要得到特别的重视。能够与AM真菌功能互补（如溶磷菌、固氮菌、生防菌等）或者促进AM真菌定殖的功能微生物，可以和AM真菌组配成复合微生物菌剂。构建AM真菌的应用技术体系，促进植物-AM真菌-土壤微生物群落的定向协同演化，才能真正实现生态系统整体正向演化，以及生态系统稳定性、生产力和恢复力的提升。

Arbuscular mycorrhizal（AM） fungi are typical symbiotic fungi for higher plants， and can form symbiotic associations with more than 70% of terrestrial plants. AM fungi receive carbohydrates from host plants， meanwhile help plants absorb mineral nutrients and water from the soil. Many studies have shown that AM symbiosis can enhance the adaptability of host plants to various environmental stresses， and synergize with other beneficial soil microorganisms （such as nitrogen-fixers， phosphate-solubilizing bacteria） to regulate plant growth and development. Since AM fungi do not have strict host specificity， they can establish hyphal links between the roots of different plants， and coordinate resource redistribution in a plant community through the extraradical hyphae network， thereby maintaining the plant community structure and function. At the ecosystem level， AM fungi are deeply involved in material cycling and regulate the ecosystem response to environmental changes. Due to the ecological importance of AM fungi， the study of AM fungal ecology and stress physiology has become a hot topic in the fields of botany， ecology and soil science. At the same time， the application of mycorrhizal technology in agricultural production and ecological restoration of degraded soils， has also received more and more attention.

Thanks to the development of relevant research technologies and the unremitting efforts of mycorrhizal researchers worldwide， the research on the ecology and physiology of AM fungi has made rapid progress in recent years， especially in the molecular mechanisms of the establishment and development of AM symbiosis， the adaptation mechanisms of the AM symbiosis to environmental stress， the interaction of hyphosphere microorganisms， and the AM fungal biogeography and community response to climate change. This has also laid a scientific foundation for the development and application of mycorrhizal technology. Based on the discipline development trends and application needs， AM fungi will be studied more systematically and in-depth in the following aspects in the future：

（1）Molecular mechanisms of AM symbiosis establishment and development. With the development of genomics， proteomics and molecular biology technologies， the molecular mechanisms of the establishment and regulation of AM symbiosis have made breakthroughs in recent years， which has also enabled progress in the pure culture of AM fungi， laying an important foundation for the physiological research and application of AM fungi. However， the signal recognition and transduction mechanism in the process of AM symbiosis establishment is not yet completely clear， and it is necessary to use multi-omics， biochemistry and other technologies to further clarify the receptors for the signal substances， reveal the signal transduction pathway， and the development， turnover and regulation mechanism of the symbiotic structure after the formation of the symbiosis. In-depth research on the molecular mechanism and signal pathway of AM symbiosis is of great scientific significance for revealing the mechanism of biological symbiosis， and can further support the development of mycorrhizal symbiosis regulation technology and pure culture of AM fungi.

（2）Ecological function of AM fungi and its regulation. The ultimate goal of AM fungal ecological research is to realize the ecological application of AM fungi and provide alternative solutions to solve ecological and environmental problems. This means that mycorrhizal ecology cannot be limited to investigation on fungal diversity， but needs to be linked with universal ecological and environmental challenges （such as global change， ecological degradation） to provide solutions for mitigating the negative impacts of environmental change and restoring the degraded ecosystems. In recent years， many researchers have carried out field experiments to investigate the response of AM fungal communities to environmental changes or human disturbances， but few studies have really considered the potential role of AM fungi in ecosystem resilience and feedback regulation of environmental changes， or in other words， few studies have really studied the ecological functions of AM fungi. Based on the important role of the AM symbiosis in plant adaptation to various environmental stresses， AM fungi cannot just passively respond to environmental changes， but are likely to directly regulate the response of plant communities to environmental changes， and are more likely to play the role of drivers of the ecological restoration process. However， there is currently a lack of scientific evaluation of the ecological importance of AM fungi， and even more of an effective way to regulate their functions. Based on this， there is an urgent need to carry out in situ ecological experiments to systematically study the synergistic responses and feedback regulation mechanisms of AM fungi and plant communities to environmental changes through regulation of AM fungal communities， explore the effectiveness and regulation pathways of AM fungi-driven ecological restoration， and lay a theoretical and methodological foundation for promoting the ecological application of AM fungi.

（3）AM fungi application technology system. Using beneficial rhizosphere microorganisms， such as AM fungi， to build functional microbiomes to enhance plant stress resistance has great application potential as a nature-based solution for ecological restoration. However， mycorrhizal technology is not just about producing inoculum to inoculate target plants. In a natural environment， the effectiveness of inoculation is affected by many factors （especially soil properties and biological interactions） and is difficult to predict. In order to tackle this challenge， it is necessary to build a mycorrhizal application technology system based on the integrity of the ecosystem to provide a systematic solution for crop production or ecological restoration. Before applying mycorrhizal technology， it is necessary to evaluate the necessity of inoculation and build a model to predict the outcome of inoculation. Secondly， it is necessary to adapt to different application scenarios， screen out suitable fungal strains， provide suitable inoculum formulations， and develop the most suitable inoculation technology. To ensure the success of inoculation， it is also necessary to establish soil eco-engineering technologies， specifically for overcoming soil barrier factors， and improving the soil environment to ensure that AM fungi can successfully colonize and function. The biological interaction between AM fungi and soil microbiome needs to be given special attention. Functional microorganisms that can complement the functions of AM fungi （such as phosphate-solubilizing bacteria， nitrogen-fixing bacteria， biocontrol agents） or promote the colonization of AM fungi can be combined with AM fungi to form composite microbial products. Only by building an ecological support system for AM fungi and promoting the directional co-evolution of plant-AM fungi-soil microbial communities， we can truly achieve the overall positive evolution of the ecosystem and improve ecosystem stability， productivity and resilience.

基金资助

科技部重点研发计划课题(2023YFF1304101)

国家自然科学基金面上项目(42177277)