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

Abstract:

[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.

Key words:Stellera chamaejasme L.;rhizosphere;microbial community structure;soil environmental factors;high-throughput sequencing