不同CO_(2)浓度下潮土真菌群落结构变化

Change of fungal community structure in fluvo-aquic soil under different CO_(2) concentrations

农业生产受CO_(2)浓度的显著影响。土壤真菌是有机质降解和养分循环的关键推动者,其对CO_(2)浓度升高的反馈尚不明确。本研究选用华北平原典型潮土作为供试土壤,设定大气、2%、4%、6%四种不同体积比的CO_(2)浓度进行微宇宙培养实验,采用Miseq高通量测序技术对真菌群落结构进行调查。结果表明:4%和6%CO_(2)浓度下,真菌α多样性显著下降。优势真菌门有子囊菌门(Ascomycota)、担子菌门(Basidiomycota)、被孢霉菌门(Mortierellomycota),担子菌门、球囊菌门(Glomeromycota)的相对丰度随CO_(2)浓度的增加而降低,而子囊菌门丰度随CO_(2)浓度的增加而增加;优势真菌属包括被孢霉属(Mortierella)、镰刀菌属(Fusarium)、Citripora、葡萄穗霉属(Stachybotrys)、腐质霉属(Humicola),其中Citripora相对丰度随CO_(2)浓度升高而降低,被孢霉属在2%CO_(2)浓度下倍增;腐质霉菌(Humicola phialophoroides)、盖姆斯帚枝霉(Sarocladium hominis)与CO_(2)浓度呈显著正相关,Citripora afrocitrina与CO_(2)浓度呈负相关。2%CO_(2)浓度下的真菌网络结构与对照基本一致,但边数显著增加;4%和6%的CO_(2)浓度下,真菌共存网络发生了显著变化,真菌群落明显分化成两个模块;基石真菌分别是土曲霉(Aspergillus terreus)、云南木霉(Trichoderma yunnanense)和刺孢霉属未定名种(Spizellomyces sp.)。本研究明确了潮土真菌对不同CO_(2)浓度的响应规律,为研究CO_(2)浓度升高对农田生态系统功能的影响提供理论参考。

Agricultural production is influenced by atmospheric CO_(2) concentration.Fungi are the key promoters of organic matter degradation and nutrient cycling in soil,but their responses to the increase of CO_(2) concentration are not clear.Miseq high-throughput sequencing technology was used to investigate the fungal community structure under four CO_(2) concentrations(ambient,2%,4%,6%)in microcosm experiments on typical fluvo-aquic soil in North China Plain.The results showed that fungalαdiversity decreased significantly at 4%and 6%CO_(2) concentration.Ascomycota,Basidiomycota,Mortierellomycota dominated the fungal community.The relative abundance of Basidiomycota and Glomeromycota decreased with the increases of CO_(2) concentration,while that of Ascomycota increased.The dominant genera included Mortierella,Fusarium,Citripora,Stachybotrys,and Humicola.The relative abundance of Citripora decreased with the increases of CO_(2) concentration,but that of Mortierella increased twofold in the condition of 2%CO_(2) concentration.CO_(2) concentration positively correlated with the relative abundance of Humicola phialophoroides and Sarocladium hominis,but negatively correlated with the relative abundance of Citripora afrocitrina.The fungal network topology in 2%CO_(2) treatment was similar to the control,but with more edges.The network topology changed obviously in 4%and 6%CO_(2) treatments,differentiating into two network modules.The keystone taxa were Aspergillus terreus,Trichoderma yunnanense,and Spizellomyces sp.This study clarified the response of fungi to different CO_(2) concentrations in fluvo-aquic soil,and provided theoretical reference for studying the impacts of elevated CO_(2) on ecosystem functions of farmland.