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

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.