中科院南京土壤研究所林先贵研究员课题组在丛枝菌根真菌的最新研究中发现，磷肥的施用有利于我国北方潮土地力的提升。
丛枝菌根真菌是陆地生态系统中关键的微生物。它们参与了碳、氮、磷等多种元素的生物地球化学循环过程，能与90%以上的陆地植物形成互惠共生体。通过“生物地下交易”法则，植物和丛枝菌根真菌进行着物质和能量的交换：植物将光合产物以碳源的形式输送给丛枝菌根真菌；作为反馈，丛枝菌根真菌为植物吸收更多的养分和水分等，以促进植物生长。此外，植物根据环境的变化，会“选择性”地放弃某些丛枝菌根真菌伙伴，将光合产物分配给其它微生物，以促进土壤肥力的可持续性发展。因此，丛枝菌根真菌群落不但可以表征土壤质量和健康，还可以敏锐地反映土壤生态系统的变化。
基于此理论，林先贵课题组利用中科院封丘农业生态实验站的农田生态系统养分平衡长期定位试验，通过454高通量基因测序技术研究了长期不同施肥措施对潮土中丛枝菌根真菌的影响。通过高通量测序，获得了59611个丛枝菌根真菌（Glomeromycota）特异性片段序列，形成70个OTUs，主要分为三个科Glomeraceae，Gigasporaceae和Acaulosporaceae。与对照和施用NK的处理相比，长期施用磷肥显著减少了潮土中丛枝菌根真菌的丰富度和多样性，其群落结构也发生明显的分异。结合环境因子的统计分析进一步显示，在施用N肥的基础上添加P肥有助于潮土肥力的提升。当作物可直接从土壤中获得足够的养分时，其对丛枝菌根真菌的依赖性下降，进而会“舍弃”部分丛枝菌根真菌，将更多的光合产物分配给其它土壤微生物，以促进土壤养分的循环过程。
这一研究结果首次深度揭示了典型农田土壤中丛枝菌根真菌群落对不同施肥的响应，为合理施肥提供了理论依据和科学指导。该研究成果发表在Environmental Science & Technology上（生物谷Bioon.com）
doi:10.1021/es3001695
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Long-Term Balanced Fertilization Decreases Arbuscular Mycorrhizal Fungal Diversity in an Arable Soil in North China Revealed by 454 Pyrosequencing
Xiangui Lin*, Youzhi Feng, Huayong Zhang, Ruirui Chen, Junhua Wang, Jiabao Zhang, and Haiyan Chu
A balanced fertilization can increase crop yields partly due to stimulated microbial activities and growths. In this study, we investigated arbuscular mycorrhizal fungi (AMF) in arable soils to determine the optimal practices for an effective fertilization. We used pyrosequencing-based approach to study AMF diversity, as well as their responses to different long-term (>20 years) fertilizations, including OM (organic manure) and mix chemical fertilizers of NP (nitrogen–phosphorus), NK (nitrogen–potassium), and NPK (nitrogen–phosphorus-potassium). Results revealed that 124 998 of 18S rRNA gene fragments were dominated by Glomeromycota with 59 611 sequences, generating 70 operational taxonomic units (OTUs), of which the three largest families were Glomeraceae, Gigasporaceae and Acaulosporaceae. In Control and NK plots, AMF diversity and richness significantly decreased under long-term P fertilizations, such as NP, NPK, and OM. Concomitantly, the AMF community structure shifted. Supported by canonical correspondence analysis, we hereby propose that long-term balanced fertilization, especially P fertilizer with additional N fertilizer, helps the build-up of soil nutrients. Consequently, some AMF community constituents are sacrificed, propelled by the self-regulation of plant-AMF-microbes system, resulting in an agro-ecosystem with a better sustainability. This knowledge would be valuable toward better understandings of AMF community in agro-ecosystem, and long-term ecosystem benefits of the balanced fertilization.
