Difference of the microbial community structure in the rhizosphere of soybean and oilseed rape based on high-throughput pyrosequencing analysis.

Abstract

Clubroot, caused by the soil-borne obligate pathogen Plasmodiophora brassicae, is one of the most severe disease in cruciferous crops. Previous studies showed that when oilseed rape was planted after soybean (namely soybean-oilseed rotation), the incidence and severity of clubroot of oilseed rape could be significantly reduced, compared with that with oilseed rape-oilseed rape conti-nuous cropping. Therefore, the soybean-oilseed rape rotation is a good way to suppress clubroot of oilseed rape. In this study, we compared the rhizosphere microbiome of soybean and oilseed rape rhizosphere soil collected from the field by 16S rRNA (for identification of prokaryotes) and the internal transcribed spacer (ITS) (for identification of fungi) sequencing. The results showed that both soybean and oilseed rape rhizosphere soils had Proteobacteria, Bacteroidetes, Acidobacteria, Actinobacteria, Ascomycota, Zygomycota, Basidiomycota and Chytridiomycota. Many microbial genera (e.g., Flavobacterium, Sphingomonas, Bacillus, Streptomyces, Pseudomonas, Trichoderma and Coniothyrium) with activities of biological control and plant growth promotion were more abundant in soybean rhizosphere soil than in the oilseed rape rhizosphere soil. The abundance of plant pathogenic bacteria and fungi was higher in the oilseed rape rhizosphere soil than in the soybean rhizosphere soil. Moreover, the soybean rhizosphere soil was enriched with Rhizobium, Bradyrhizobium (both for nitrogen fixation), and arbuscular mycorrhizal fungus (Glomus). These results indicated that soybean rhizosphere soil could promote the growth and proliferation of beneficial microorga-nisms, but inhibit that of plant pathogens. Our results provide evidence for explanation of the effectiveness of soybean-oilseed rape rotation to control clubroot of oilseed rape and provide potential bio-control resources for clubroot prevention.