碧塔海湿地不同水分梯度下土壤真菌群落结构及功能类群研究

Soil fungal community structure and functional groups under different moisture gradients in Bitahai Wetland, Southwest China

摘要:

【目的】通过对碧塔海湿地不同水分梯度下土壤真菌群落结构及功能类群的分析，以期为湿地资源管理和生态恢复提供参考。【方法】选择滇西北碧塔海湿地不同水分梯度下的土壤，包括常年淹水的沼泽湿地(swamp wetland，SW)、季节性淹水的沼泽化草甸(swamp meadow，SM)和无淹水的草甸(meadow，M)，利用Illumina高通量测序和FUNGuild比较分析不同水分梯度下土壤真菌群落结构和功能类群，并探究环境因子对真菌群落的影响。【结果】碧塔海湿地土壤真菌α多样性在不同水分梯度上无显著差异。非度量多维尺度分析和相似性分析表明真菌β多样性在不同水分梯度上存在显著的差异(R=0.501，P=0.001)。碧塔海湿地中真菌优势门为子囊菌门、担子菌门、隐菌门和被孢霉门。在不同水分梯度上担子菌门、被孢霉门和隐真菌门丰度存在显著差异(P<0.05)。优势科为火丝菌科、被孢霉科、古生菌科和珊瑚菌科(P<0.05)。相关分析显示，土壤pH、总氮、硝态氮、铵态氮、铁、钾、蔗糖酶和植物PCoA1与真菌α多样性呈显著相关(P<0.05)。冗余分析和相关性热图分析结果表明，含水率、铵态氮、脲酶、植物Shannon指数是驱动真菌β多样性变化的关键环境因子(P<0.05)。此外，方差分解结果显示真菌群落不仅受到单一环境条件的影响，同时受到各环境因子之间共同作用的影响，特别是土壤环境因子和植物群落的共同作用。碧塔海湿地土壤真菌功能营养型以腐生营养型和腐生-共生过渡型为主；沼泽湿地以内生-植物病原菌为主要优势类群，沼泽化草甸和草甸均以未定义腐生菌为主要优势类群；随着水分减少，病原-腐生-共生过渡型真菌增加，功能类群表现出更高的复杂性。【结论】水分梯度的变化影响碧塔海湿地土壤真菌结构和功能类群，其土壤真菌多样性和组成受多重环境因子的影响，环境因子对真菌多样性以及在门分类水平上的影响具有一定的差异性。

Abstract:

[Objective] This study aims to analyze the fungal community structure and functional groups under different moisture conditions in Bitahai Wetland, which is expected to serve as a reference for wetland resource management and ecological restoration. [Methods] Perennially submerged swamp wetland (SW), seasonally submerged swamp meadow (SM), and non-submerged meadow (M) in Bitahai Wetland, Southwest China were investigated. Based on Illumina high-throughput sequencing and FUNGuild, the soil fungal community structure and functional groups of the three types were analyzed and compared, and the influence of key environmental factors on the fungal community was probed. [Results] The alpha diversity of soil fungi showed no significant difference among SW, SM, and M. Non-metric multidimensional scaling and similarity analysis suggested that beta diversity was significantly different among the moisture gradients (R=0.501, P=0.001). Bitahai Wetland was dominated by Ascomycota, Basidiomycota, Rozellomycota, and Mortierellomycota. The abundance of Basidiomycota, Rozellomycota, and Mortierellomycota varied significantly across different moisture gradients (P<0.05). Pyronemataceae, Mortierellaceae, Archaeorhizomycetaceae, and Clavariaceae were the dominant soil fungal families (P<0.05). Correlation analysis indicated that soil pH, total nitrogen, nitrate nitrogen, ammonium nitrogen, iron, potassium, and sucrose, and plant PCoA1 were in positive correlation with alpha diversity of soil fungi (P<0.05). Redundancy analysis and heat map analysis showed that soil water content, ammonium nitrogen, urease, and plant Shannon index were the main causes of beta diversity variation (P<0.05). Variance partitioning showed that the fungal community was affected by both single environmental factors and the interaction among various environmental factors, especially the interaction of soil factors and plant community. The trophic types of soil fungi in the Bitahai Wetland were mainly saprotroph and saprotroph-symbiotroph. SW was dominated by endophytic-phytopathogenic fungi, and SM and M by undefined saprophytes. As the moisture decreased, pathotroph-saprotroph-symbiotroph increased and functional groups showed higher complexity.[Conclusion]Moisture influences the structure and functional groups of soil fungi in the Bitahai Wetland, and its soil fungal diversity and composition are influenced by multiple environmental factors. The influence of environmental factors on fungal diversity and fungal phyla is different.