Relationship Between Soil Microbial Communlity Characteristics And Colonization Ability Of Ralstonia Solanacearum

Tobacco wilt is a typical soil-borne disease that seriously harms the production of high-quality tobacco leaves.At present,the research on the infection mechanism of wilt mainly focuses on the analysis of plant response characteristics,while the research on the microecological effect of wilt in soil needs to be further explored.Based on this,soil suspension with different dilution factors was used(D0 treatment:dilute 10~0 times soil suspension;D2 treatment:dilute 10~2 times soil suspension;D4 treatment:dilute 10~4 times soil suspension)inoculated and sterilized soil,simulated different microbial diversity soil environment,based on the previous research of the research group,the suspension of ralstonia solanacearum was quantified,the effect of ralstonia solanacearum infection on soil microbial community composition and potential function was discussed,and the intrinsic relationship between the change of microbial community characteristics and the proliferation of ralstonia solanacearum was preliminarily established,and the main results were as follows:(1)The soil differentiation characteristics of soil microbial community can be well simulated by inoculation and sterilization of suspension with different dilution factors of tobacco soil,and the Chao1 index of soil bacterial alpha diversity decreases with the increase of dilution factor,while the fungus shows the opposite trend;At the same time,bacterial and fungal communities were clearly separated.(2)There were differences in the colonization capacity of ralstonia solanacearum in soils with different microbial community characteristics,and the overall fluctuation and decline trend was shown within 30 days after inoculation,and there was no significant difference between treatments at 30 days.It suggests that the colonization of pathogenic bacteria in soil,in addition to the influence of soil microbial diversity,may also involve more interactions between microbial species and other environmental factors.(3)The infection of ralstonia solanacearum caused severe fluctuations in soil physicochemical traits with different microbial community characteristics.In the D0,D2and D4 treatments of soils with different microbial community characteristics within 30 days,D2 treatment was the weakest acidity.OM treated with D0 had the highest mean AN content,lower D2 and D4 treatments,and the opposite was true for AK.The mean content of AP was the highest in D4 treatment and the lowest in D2 treatment.The mean content of MC was the highest in D2 treatment and the lowest in D4 treatment.The mean content of MN was the highest in D0 and the lowest in D2.The mean content of MP was the highest in D4treatment,and the D0 and D2 treatment were lower.The mean content of CAT,URE and ACP was higher in D0 treatment,and the average content of D4 treatment was lower.(4)The period of severe change of copy number of soil wilt bacteria(0d,1d and 5d)was selected for microbial community characteristics,and the results showed that the soil microbial community composition and potential functions changed significantly during the drastic change of wilt.The diversity index of bacterial Chao1 showed an overall downward trend,while the fungus showed an upward trend,and all are treated with the highest D0.Microbial communities are clearly separated,and bacteria and fungi may be affected by similar environmental factors;The abundance of Bacillus,Ammoniphilus,pululanibacillus,and Paenibacillus in the phylum Firmicutes showed a trend of first increasing and then decreasing,and the highest treatment was D4.The abundance of Penicillium in the Ascomycota phylum showed an increasing trend,and D4 was the highest.Correlation network analysis suggests that Aneurinibacillus and Effusibacillus may be key species associated with ralstonia solanacearum infestation.Similarly,the potential functions of soil microorganisms vary depending on the treatment.(5)The changes of microbial communities under different treatments were closely related to the changes of soil environmental factors,and the structural equation model showed that in the soil with low proliferation rate of pathogenic bacteria,lower enzyme activity led to soil nitrogen loss,which promoted the increase of soil abundance of Aneurinibacillus and Effusibacillus,thereby improving soil nutrients and reducing the degree of infection of ralstonia solanacearum in the soil.