The Effect Of TMV Infection On The Tobacco Soil Microorganisms And Soil Physicochemical Property

The interaction between soil microorganisms and plant pathogens has an important impact on plant health.The occurrence of plant diseases can affect soil microbial ecology and make significant changes in soil microbial community structure and diversity.Nowadays,there were many studies on the interaction between soil-borne pathogenic fungi and bacteria and other soil microorganisms,but there are few studies on plant viruses and soil microorganisms.Tobacco mosaic virus（TMV）is one of the main diseases of tobacco,which can be transmitted from the root micro-incision through virus liquid.There is still no stable and efficient control method at now.In this paper,the effects of TMV on the abundance,structural composition and diversity of microbial community in rhizosphere soil of tobacco were systematically studied by Real-Time Quantitative PCR（RT-q PCR）and High-throughput sequencing analysis technology,providing a theoretical basis for the prevention and control of plant virus diseases.The main results are as follows:1.In this experiment,the infection of TMV in soil was studied under greenhouse conditions.It was found that TMV could infect pepper,cabbage,cucumber and other crops in soil,which proved the soil-borne of TMV.RT-q PCR showed that the dilution end-point of TMV in soil was 1×10^-4and the minimum infection concentration in soil was from 2.06×10⁶copies/g to 2.06×10⁷copies/g.2.The infection of TMV in soil can significantly change the community structure and diversity of soil rhizosphere microorganisms.At the phylum level,the relative abundance of Proteobacteria decreased,while the relative abundance of Proteobacteria and Patessibacteria increased significantly.In addition,the dominant species in the microbial community were also affected by time,such as Bacillus,Mosaic and Bordetella,which were relatively high in the treatment group inoculated with TMV and gradually decreased with time;According to the analysis of microbial alpha diversity index,the Chao1,Ace,Shannon and Simpson indexes of bacterial communities were significantly decreased,indicating that TMV reduced the diversity among bacterial communities.For fungal communities,the same trend was observed in sterilized soils,while the alpha diversity index increased in unsterilized soils.NMDS analysis showed that TMV infection had significant influence on microbial community structure.LEf Se analysis showed that there were significantly different species between the TMV-inoculated group and the non-inoculated group,such as Burkholderia,Saccharimonadales and Mosaic.There are significant differences in biocontrol beneficial microorganisms and potential pathogenic microorganisms among fungal communities.The co-occurrence network analysis showed that TMV infection could significantly reduce the complexity and stability of the ecological network of bacterial communities,and promote the positive correlation between bacterial communities,which is indicated that TMV could promote the development of bacterial communities in soil to a mutually beneficial symbiosis model.For fungal communities,the infection of TMV increases the complexity of molecular networks,which can drive the symbiosis mode of fungal communities to evolve in different directions.Based on comprehensive analysis,Devosiaceae,Saccharimonadales,Sediminibacterium,Burkholderia and Xenomyrothecium were the key microorganisms among microbial networks.The functional prediction analysis of microbial communities showed that TMV could significantly reduce the absorption and utilization of nitrogen by bacteria communities,and had a great influence on saprophytic fungi.3.TMV can significantly affect the physicochemical properties of tobacco rhizosphere soils.The study found that TMV infection could significantly reduce soil p H,compared with the control group decreased by about 6.40%,suggesting that TMV may aggravate soil acidification.TMV significantly affected the content of SOM,which is significantly decreased in sterilized soil.For total nutrients,the TN content in the uninfected soil was significantly higher than that in the infected soil,and the TK content showed the opposite trend.There was no significant difference in the effect of TMV infection on TP content.For the content of available nutrients,the content of TMV-inoculated treatment group was significantly different from that of non-inoculated treatment group.The content of Ava-K,Ava-P and NO₃^--N was higher in the inoculated treatment group,and the content of NH₄⁺-N was higher in the non-inoculated treatment group.The correlation analysis between soil physicochemical properties and microbial community showed that the contents of TK and SOM were the main factors affecting the development variation and structural composition of microbial system.