丛枝菌根真菌对铅胁迫下百喜草（Paspalum notatum）根际-非根际细菌群落结构的影响
- Effect of arbuscular mycorrhizal fungi on bacterial community structure in the rhizosphere-non-rhizosphere of Paspalum notatum under lead stress
- 原奥
- 山西大学资源与环境工程研究所，黄河流域资源增效减碳教育部工程研究中心
- 宋慧平
- 山西大学资源与环境工程研究所，黄河流域资源增效减碳教育部工程研究中心
- 摘要：为探究植物根系、丛枝菌根真菌（AMF）及重金属铅（Pb）三者联合作用对土壤细菌群落的影响，设计了盆栽试验。选用百喜草作为受试植物，模拟不同程度（低、轻、重）的Pb污染土壤环境，设置加AMF和不加AMF两个处理，通过尼龙网限制植物根系，划分根际区、近根区及远根区。采用高通量测序和生物统计学分析方法研究了土壤细菌的群落组成、多样性以及细菌网络结构随根系距离、Pb浓度和AMF的变化规律，最后构建了结构方程模型（SEM）来进一步阐明植物根系、AMF、重金属及土壤细菌群落间的相互作用关系。结果表明：AMF和Pb都显著影响了植物的生长发育及其根系土壤中的营养物质和细菌的群落结构；Pb胁迫显著降低细菌种类的多样性和丰富度，但同时也产生了抗金属Pb的细菌品种Bacteroidetes（拟杆菌门）；AMF提高了细菌群落的多样性，表明AMF在减轻重金属Pb对土壤细菌群落的负面影响方面具有重要作用。主坐标分析（PCoA）揭示了Pb和AMF在不同方向上影响了细菌群落的演化。共现网络分析表明添加AMF后，土壤中微生物群落的网络结构更简单，稳定性更高，这种稳定性的维持有助于土壤生态系统在面对环境压力时保持其功能和服务。综上所述，AMF通过促进植物对营养物质的吸收和利用、增强植物的抗逆性、调节土壤微生物群落，以及维持土壤微生物网络的稳定性，从而改善了受Pb污染的土壤微环境，并减轻了Pb对植物和土壤细菌的胁迫。这些作用有助于在变化的环境条件下维持土壤生态系统的功能和服务，对保持土壤环境的长期稳定性具有重要意义。研究结果可为受重金属污染土壤的生态修复及可持续利用提供科学依据。
- Abstract：A pot experiment was designed to explore the synergetic effects of plant roots, arbuscular mycorrhizal fungi (AMF), and heavy metal Pb on soil bacterial community. Paspalum notatum was chosen as the test plant, and soil environments with different degrees (low, mild, and severe) of Pb contamination were simulated. Two treatments were set up: with and without AMF addition. The plant root systems were confined using nylon nets, and which areas were divided into the rhizosphere, proximal root zone, and distal root zone. High-throughput sequencing and biostatistical analysis methods were employed to investigate the community composition, diversity, and bacterial network structure of the soil bacteria in relation to root distance, Pb concentration, and AMF. Finally, a structural equation model (SEM) was established to further verify the interaction relationships among plant roots, AMF, heavy metals, and the soil bacterial community. The results indicated that both AMF and Pb significantly influenced the growth and development of plants, as well as the nutrient substances and bacterial community structure in the root soil. Pb stress significantly decreased the diversity and abundance of bacterial species, while the concurrently resistant Bacteroidetes was generated to metal Pb. AMF enhanced the diversity of the bacterial community, indicating that AMF plays a crucial role in alleviating the negative impacts of heavy metal Pb on the soil bacterial community. Principal coordinate analysis (PCoA) revealed that Pb and AMF influenced the evolution of the bacterial community in different directions. Co-occurrence network analysis demonstrated that after the addition of AMF, the network structure of the bacterial community in the soil became simpler and more stable. The maintenance of stability is benefit to maintain the functions and services of soil ecosystem when confronted with environmental pressure. In conclusion, The application of AMF improved the microenvironment of Pb-contaminated soil and mitigated Pb-induced stress on plants and soil bacteria through facilitating nutrient absorption and utilization, enhancing plant stress tolerance, regulating the bacterial community in soil, and maintaining the stability of the soil bacterial network. These effects are beneficial for maintaining the functionality and services of the soil ecosystem under varying environmental conditions and are of great significance for ensuring the long-term stability of the soil environment. The research findings can provide scientific views for the ecological restoration and sustainable utilization of soil contaminated by heavy metals.
