Abstract: [Objective]Soil microbes have important ecological functions in forest ecosystems. The status of microbial community diversity in rhizosphere soils of oil tree peony may lay a solid foundation for revealing the mechanism of the formation of the poor soil with long-term continuous cropping.[Method]The technique of IlluminaMiSeq high-throughput sequencing was used to detect abundance and diversity of the V3-V4 region of 16S rRNA genes of bacteria in the rhizosphere soils in which the oil tree peony ‘Fengdan’ (Paeonia ostii) were planted for 2, 4, 5, 10 and 32 years respectively, to study the effects of continuous cropping system on the structure and diversity of soil bacterial community composition.[Result]Total of 2 366 OTUs covering 24 Phyla, 79 Classes, 113 Orders, 117 Families, and 103 genera were obtained from 15 soil samples. The result showed that the different bacterial composition as follows:Proteobacteria (34%), Acidobacteria (14%), Planctomycetes (16%), Actinobacteria (10%).The four groups were the predominant bacterial compositions on the phylum level, while Deltaproteobacteria (26%), α-deformation (25%), Betaproteobacteria (15%) and Gammaproteobacteria (15%) in Proteobacteria phylum; Acidobacteria (44%) and Acinetobacter (12%) in Acidobacteria phylum; Phycisphaerae (27%) and (Planctomycetia) (60%) in Planctomycetes phylum; Actinobacteria (25%), actinomycetes (18%), Thermoleophilia (17%), MB-A2-108 (15%) and Rubrobacteria (10%) in Actinobacteria phylum were the dominant bacterial types on the class level.[Conclusion] The soils with different planting years had specific bacterial community composition, high abundance and low abundance species. With the increasing of cropping years, Acidobacteria was accumulated, Chlorobi and Fibrobacteres were emerged, Actinobacteria, Proteobacteria and Planctomycetes etc. were decreased; while Verrucomicrobia, WS3 and SBR1093 etc. were disappeared successively. It was speculated that continuous cropping of a single plant (oil tree peony) may be one of the important reasons for the selective inhibition of soil bacteria, occurrence of soil disease and soil degradation. Microbial diversity analysis of rhizosphere soil in the plantation of oil tree peony has an important ecological significance in maintaining soil microenvironment.

Key words: Paeonia ostii, continued cropping system, rhizosphere soil, Illumina high-throughput sequencing, bacteria diversity