Rhizosphere Microbial Interactions With Plant Roots Based On Synthetic Communities

Rhizosphere microorganisms play an important role in plant growth and health,and their construction model has been a focus of research.In the feedback loop of plant-soilmicrobial interaction,plant root exportation will affect the direction of rhizosphere microbial succession,and then react on plants when the rhizosphere microbial community becomes stable.However,the mode of microbial community succession driven by root extions is still unclear,and the feedback effect of rhizosphere microorganisms on plant root extions production is also poorly studied.This paper focuses on the interaction between soybean root system and its rhizosphere microbial community,based on the strains obtained by culture group technology,to construct the characteristic synthetic core microbial community of soybean in different growth stages.On the one hand,microcosmic experiments were conducted to analyze the effects of different root exportation components on microbial community structure,and to clarify the process and mechanism of rhizosphere microbial community construction and succession driven by roots along with plant growth.On the other hand,the effects of rhizosphere core microbial communities on the composition of plant root exudes at different periods were explored through root-divided inoculation experiments,and the feedback mechanism of rhizosphere microbial community structure succession on plant roots was revealed.Finally,the dynamic interaction between synthetic community and plant root system was elucidated.The main research results of this paper are as follows:1.It is clear that under controlled conditions,the succession pattern of synthetic and natural rhizosphere microbial communities is similar.Combined with the results of species composition analysis and Prucker analysis,it was found that the succession pattern of artificial community was more representative to that of natural soil community.This indicates that the synthetic community constructed by pure culture can better simulate the composition and succession characteristics of the natural community,and can be used to explore the process of plant-rhizosphere community interaction.2.The influence model of important components of root exportation on rhizosphere microbial community was revealed.Soil incubation experiments with manual screening of root exudates showed that:(1)Daidzein can change the community structure of Agromyces and Phyllobacterium,which are related to nitrogen fixation.(2)Glucose can affect the abundance of aerobic bacteria and anaerobic bacteria because of its positive and negative effects.(3)The effect of Lysobacter and Bacillus on coumaric acid changed the community structure.Based on the analysis of microbial community structure,we speculated that carbon sources such as glucose might dominate the transformation from protosoil microbial community to rhizosphere microbial community.Small signaling substances such as daidzein may play an important role in the temporal succession of rhizosphere microbial communities.3.The influence of rhizosphere microbial community on root exudates in different periods of soybean was investigated.The root experiment showed that the composition of root exudates was different due to the access of synthetic communities at different stages of soybean.Among them,the early community made soybean roots release more nucleotides and their derivatives,organic acids and their derivatives,while the late community made soybean roots release more plant hormones.This may be due to the differences in the degree of domestication of microbial communities and their matching with roots in different periods.In conclusion,this study reveals the dynamic interaction mode between microorganisms and plant root exudes by constructing a synthetic community that is highly representative of the natural rhizosphere microbial community,which provides a new reference for the study of the microbial community in natural environment and provides important support for indepth discussion of the rhizosphere microbial community construction mechanism and ecological function.