根际细菌在长刺蒺藜草氮素利用中的作用

Research on the effect of rhizosphere bacteria on nitrogen utilization of Cenchrus longispinus

【目的】入侵植物长刺蒺藜草在贫瘠土壤中能够快速生长和扩张,形成单一优势群落。本研究分析长刺蒺藜草入侵对土壤氮循环及相关微生物群落的影响,以期为揭示其入侵的微生态学机理提供理论依据。【方法】利用16S rRNA和nifH基因扩增子高通量测序技术分析长刺蒺藜草、披碱草、冰草、狗尾草根际土壤细菌及固氮菌群落结构和功能的差异。【结果】长刺蒺藜草入侵显著增加了土壤全氮和硝态氮含量,显著降低了水溶性氮和铵态氮的含量。根际土壤高通量分析结果表明:芽孢杆菌、蓝细菌、念珠藻、鱼腥藻、厚壁菌门在长刺蒺藜草固氮菌群落中有明显富集;长刺蒺藜草可能通过增加变形菌门的相对丰度,降低蓝细菌和厚壁菌门的相对丰度来提高其固氮能力,促进对氮素的吸收利用;硝化螺旋菌属和阿菲波菌属在长刺蒺藜草对氮素的利用过程中影响较小。【结论】长刺蒺藜草通过改变入侵地根际土壤细菌和固氮菌的群落结构,影响根际土壤的氮素环境,以利于自身生长。

【Aim】The invasive plant Cenchrus longispinus can grow rapidly and expand its population in nutrient-poor sandy soils,forming a single dominant community.This study analyzed the effect of C.longispinus on soil nitrogen cycle-related microbial communities to provide a theoretical basis for revealing the microbiological mechanisms of its invasion.【Method】High-throughput sequencing of 16S rRNA and nifH gene amplicons was applied for analyzing the differences in community structures and functions of bacteria and nitrogen-fixing microorganisms in the rhizosphere soils of C.longispinus,Elymus dahuricus,Agropyron cristatum,and Setaria viridis.【Result】C.longispinus could significantly elevate the levels of total nitrogen and nitrate nitrogen and reduce the contents of water-soluble nitrogen and ammonium nitrogen in soil.The results of soil high-throughput sequencing showed that Bacillus,Cyanobacteria,Nostocales,Anabaena,and Firmicutes were enriched in the nitrogen-fixing communities around the rhizosphere soil of C.longispinus.C.longispinus increased the relative abundance of Proteobacteria and decreased those of Cyanobacteria and Firmicutes,promoting its capacity for nitrogen fixation and utilization.Nitrospirota and Afipia were barely involved in nitrogen utilization by C.longispinus.【Conclusion】C.longispinus could affect the community structures of bacteria and nitrogen-fixing microorganisms in the rhizosphere soil of invasive areas to improve soil nitrogen for its growth.