Effects Of Different Phosphorous Concentration On Microbial Community Structure And Function In Soybean Rhizosphere

Microbial community in the rhizosphere plays an important role in soil nutrient availability and plant growth.Difference concentrations of phosphorus availability change the root exudates and root architecture,However the effect on microbial community in the rhizophere is unclear.In the present study,the effects of phosphorus deficiency on microbial community in soybean rhizosphere were studied by using the Biolog and PCR-DGGE methods, and the DGGE banding patterns analysed by microbial species diversity index,cluster analysis and principal component analysis.Phosphorous(P) as one of the most important elements on plant growth,which play a significant stimulation effect on root growth and root system characters.The results of this study indicated that P enhanced both soybean shoot and root biomass and this effect is closed related to sampling stage and soybean genotypes.With the increase of phosphorus concentration and growth period of the growth stage extension,root length and root surface area showed an increase trendency with soybean growth.The results indicate that excessive phosphorus isn't improved root characters,but it had effects on inhibiting soybean root growth.Biolog data analysis showed that phosphorus concentration had impact on the metabolic function of microbial community in soybean rhizosphere.The microbial metabolic activity in rhizosphere of two genotypes soybean under three concentration of phosphorus were difference,and AWCD values were P₀＞P₁＞P₂.The principal component and cluster analysis of metabolic activity showed that under P₀ treatment,metabolic activities in rhizosphere under two soil types were clustered together,however under P₁ and P₂ treatments,metabolic activities in rhizosphere were chustered independently.DGGE analysis results showed that the soil types are dominant factor in changing bacterial and fungal communities in soybean rhizosphere.However,under the same soil condition,microbial community structure in soybean rhizosphere shifted with growth stages. The principal component and cluster analyses on microbial community showed that under different phosphorus concentrations and different genotypes,microbial community at the same reproductive period can be divided into independence groups.Sequence analysis of the dominant bands suggested that bacteria belonging to Proteobacteria,Actinobacteria,Verrucomicrobia,Bacteriodetes,and Gemmatimonadetes; fugun belonging to Ascomycota and Basidiomycota were commonly inhabited in the soybean rhizosphere.