甘肃典型高寒草原退化植物瑞香狼毒对根际土壤微生物群落的影响研究

目的] 瑞香狼毒（Stellera chamaejasme L.）为瑞香科狼毒属（Stellera）多年生草本植物，是我国草地退化的标志性植物之一。本研究旨在探究甘肃高寒草原主要毒草瑞香狼毒根际微生物群落结构及其与土壤环境因子和酶活性之间关系，为治理因瑞香狼毒入侵引起的草地退化提供理论依据。方法] 采用Illumina MiSeq高通量测序技术对甘肃不同地区高寒草原的瑞香狼毒根际土壤微生物组成及多样性进行分析，并进一步分析土壤理化性质和酶活性与微生物群落的相关性。结果] 不同地区瑞香狼毒根际土壤pH随海拔升高呈现上升趋势，土壤中大量和微量营养元素含量以及土壤酶活性的变化各异。在门水平上，子囊菌门（Ascomycota）、接合菌门（Zygomycota）和担子菌门（Basidiomycota）在根际土壤真菌中占优势地位；放线菌门（Actinobacteria）、变形菌门（Proteobacteria）、酸杆菌门（Acidobacteria）在根际土壤细菌中属于优势类群。海拔2964 m样地的真菌和细菌OTU（operational taxonomic unit）数量和Shannon多样性指数均高于其他4个采样点（海拔2373、2608、2733、3280 m）。RDA（redundancy analysis）分析结果显示，瑞香狼毒根际土壤微生物不同，受土壤环境因子的影响不同；相关系数表明，土壤真菌多样性与土壤钾、磷、铁、钙、钼、海拔、土壤水分、过氧化物酶呈正相关，与土壤温度、多酚氧化酶、脱氢酶、蔗糖酶、碱性磷酸酶呈负相关；土壤细菌与土壤pH、钾、磷、镁、钙、土壤水分呈负相关，与多酚氧化酶、过氧化物酶、脲酶、脱氢酶、蔗糖酶、酸性磷酸酶、碱性磷酸酶呈正相关。结论] 甘肃省不同地区高寒草原瑞香狼毒根际微生物群落组成和多样性差异明显，土壤理化性质与土壤真菌具有较强的正相关关系，而土壤酶则更多地影响着土壤细菌群落的组成和多样性。

Effects of degraded plant Stellera chamaejasme L. on the rhizosphere soil microbial communities in typical alpine grassland, Gansu Province

Objective] Stellera chamaejasme L., a perennial herb of Stellera, is one of symbolic plants of grassland degradation in China. The purpose of this study was to explore the microbial community structure in the rhizosphere of Stellera chamaejasme L. and its relationship with soil environmental factors and enzyme activity in Gansu alpine steppe, so as to provide a theoretical basis for controlling grassland degradation caused by Stellera chamaejasme L. invasion. Methods] The Illumina MiSeq high-throughput sequencing technology was used to analyze the composition and diversity of rhizosphere soil microbes of Stellera chamaejasme L. in various regions of Gansu, and further analyze the relationship between soil physical and chemical properties, enzyme activities and microbial communities. Results] The results indicated that the pH value of the rhizosphere soil of Stellera chamaejasme L. in different areas increased with altitude, showing an upward trend. The content of macro and micronutrient elements in the soil, and the changes of soil enzyme activities were different. At the phylum level, Ascomycota, Zygomycota and Basidiomycota are dominant in rhizosphere soil fungi. Actinobacteria, Proteobacteria and Acidobacteria belong to the dominant groups in rhizosphere soil bacteria. The numbers of fungi and bacteria OTU (Operational taxonomic unit) and Shannon diversity index of altitude 2964 m are higher than the other four sample points (altitude 2373 m, 2608 m, 2733 m, 3280 m). Redundancy analysis showed that the soil microbes in the rhizosphere of S. chamaejasme are different and are affected differently by soil environmental factors. The correlation coefficient showed that the diversity of soil fungi is positively correlated with soil potassium, phosphorus, iron, calcium, molybdenum, altitude, soil moisture, and peroxidase, as well as soil temperature, polyphenol oxidase, dehydrogenase, invertase, and alkaline phosphatase is negatively correlated. Soil bacteria are negatively correlated with soil pH, potassium, phosphorus, magnesium, calcium, and soil moisture, and positively correlated with polyphenol oxidase, peroxidase, urease, dehydrogenase, invertase, acid phosphatase, and alkaline phosphatase. Conclusion] The composition and diversity of the rhizosphere microbial community of S. chamaejasme in the alpine grasslands of Gansu Province are obviously different. In addition, the physical and chemical properties of soil have a strong positive correlation with soil fungi, and the soil enzymes have more influence on the composition and diversity of soil bacterial communities.