黄河三角洲典型植被下真菌群落结构组成

Structures of fungal communities in soil of typical plants in the Yellow River Delta

摘要:

目的 微生物是潮间带地球化学元素迁移转化的重要执行者。真菌在碳、氮、磷循环及有机污染物降解等方面扮演重要角色。方法 选取黄河三角洲潮间带典型植被芦苇(Phragmites australis)、柽柳(Tamarix chinensis)、盐地碱蓬(Suaeda salsa) (潮间带盐地碱蓬和盐碱地盐地碱蓬)的根际和非根际土壤为研究对象，通过高通量测序技术研究不同植被下的真菌群落结构差异。结果 植物根际中，盐碱地盐地碱蓬的真菌丰度、丰富度及均匀度最高，与其他3种植物的真菌群落结构相似性最低。在植物非根际中，芦苇的真菌丰度最高，盐碱地盐地碱蓬的丰富度最高，柽柳的真菌分布最均匀；芦苇与盐碱地盐地碱蓬之间的真菌群落结构相似性最高。4种植物根际和非根际共有优势真菌门为子囊菌门(Ascomycota)、担子菌门(Basidiomycota)。不同植物的功能真菌存在差异，芦苇、柽柳、盐碱地盐地碱蓬的根际、非根际优势功能真菌主要为腐生真菌，如链格孢属、曲霉属，它们能够分解有机养料产生腐殖质，从而改善土壤通气性，改良土壤理化性质；以上3种植物根际中腐生真菌占比分别为13.60%、6.33%、20.16%，非根际土壤中分别为11.98%、24.25%、8.52%。在柽柳非根际中，还发现了能与植物共生且耐盐的短梗霉属(1.51%)，这种真菌可与植物协同作用，有效防治土壤盐碱化。潮间带盐地碱蓬根际土壤中的优势功能真菌主要为篮状菌属(15.90%)、葡萄穗霉属(0.53%)等参与糖类分解的真菌，它们能够分解纤维素为葡萄糖，产生腐殖质，进而形成稳定的土壤团粒结构，改善土壤通气性。盐碱地盐地碱蓬根际土壤中还存在木霉属(0.13%)，这种真菌可以促进土壤氮磷转化，避免土壤中无机磷含量过高造成土壤污染。在非根际土壤中，以上功能真菌的相对丰度均小于0.10%。此外，在植物非根际土壤中，还发现了能够降解持久性有机污染物(persistent organic pollutants, POPs)的原毛平革菌属(0.15%)和降解醌类物质的青霉属(1.16%)，这些真菌为有机污染土壤的修复提供微生物资源；以上真菌在植物根际中未检测到。土壤环境因子与真菌群落结构关系表明，根际真菌的多样性、均匀度与电导率(electrical conductance, EC)、钙离子浓度、盐度呈正相关关系；非根际真菌群落的丰富度和多样性均与总氮呈正相关关系，而均匀度则与pH、盐度、氨氮呈正相关关系。结论 本研究为明确黄河三角洲潮间带真菌群落的分布结构和功能奠定了基础，为将来利用相关微生物资源来改善土壤结构、维持生物多样性、治理有机物污染以及盐碱地生态保护与修复等提供理论依据。

Abstract:

Objective Microorganisms are key executors of the migration and transformation of geochemical elements in intertidal zones. Fungi play an important role in the cycling of carbon, nitrogen, and phosphorus and the degradation of organic pollutants.Methods In this study, soil samples were collected from the rhizosphere and non-rhizosphere of Phragmites australis, Tamarix chinensis, and Suaeda salsa (intertidal zone and saline inland), which were the typical intertidal plants in the Yellow River Delta. The fungal community structures in different soil samples were investigated by high-throughput sequencing.Results In the rhizosphere, the soil sample of S. salsa in saline inland showed higher fungal abundance, richness, and evenness than other soil samples, with a distinct fungal community structure. In the non-rhizosphere, the fungal abundance, richness, and evenness were the highest in the soil samples of P. australis, S. salsa in saline inland, and T. chinensis, respectively, and the fungal community structure of P. australis was similar with that of S. salsa in saline inland. Ascomycota and Basidiomycota were the dominant fungal phyla in both the rhizosphere and non-rhizosphere. However, the functional fungi were different among plants. Saprophytic fungi such as Alternaria and Aspergillus were the dominant functional fungi in the rhizosphere and non-rhizosphere of P. australis, T. chinensis, and S. salsa in saline inland, with the relative abundance of 13.60%, 6.33%, and 20.16% in the rhizosphere and 11.98%, 24.25%, and 8.52% in the non-rhizosphere, respectively. Saprophytic fungi were essential for the production of humus by decomposition of organic matter and the improvement of soil aeration and physicochemical properties. Aureobasidium (1.51%) were identified in the non-rhizosphere of T. chinensis, and they were haloduric fungi and could work synergistically with plants to prevent soil salinization. The dominant functional fungi in the rhizosphere of S. salsa in intertidal zone were mainly Talaromyces (15.90%) and Stachybotrys (0.53%), which were involved in sugar degradation. They were able to break down cellulose into glucose, produce humus, and form a stable soil aggregate structure to improve soil aeration. Trichoderma (0.13%) were identified in the rhizosphere of S. salsa in saline inland, and they could promote soil nitrogen and phosphorus conversion and prevent the soil pollution caused by excessive inorganic phosphorus. The relative abundance of functional fungi was less than 0.10% in the non-rhizosphere. In addition, Phanerochaete (0.15%) capable of degrading persistent organic pollutants and Penicillium (1.16%) capable of degrading quinones were identified in the non-rhizosphere, providing microbial resources for the remediation of organic pollution in soil. However, they were not identified in the plant rhizosphere. The fungal diversity and evenness in the rhizosphere were positively correlated with soil factors such as electrical conductance (EC), calcium concentration, and salinity. In the non-rhizosphere, the fungal richness and diversity were positively correlated with total nitrogen, while the fungal evenness was positively correlated with pH, salinity, and ammonia nitrogen.Conclusion This study established a framework for understanding the structures and functions of fungal communities in the intertidal zone of the Yellow River Delta. Additionally, it provides a theoretical foundation for the future application of different functional fungi in soil structure improvement, biodiversity maintenance, organic pollution treatment, ecological protection, and saline-alkali land restoration.