Response Characteristics Of Rhizosphere Soil Microecology Of Tobacco Plants To Tobacco Root-knot Nematode Disease

Tobacco root-knot nematode disease is caused by Meloidogyne spp.Soil-borne diseases caused by infection with tobacco root system bring greater economic losses to tobacco leaf production.Rhizosphere is the main activity space of root-knot nematodes,and it is also an important space for root-soil interaction,and the changes of rhizosphere soil microecology are closely related to the survival and activity of root-knot nematodes.In order to further clarify the response characteristics of the soil microecology of tobacco rhizosphere to tobacco root knot nematode disease,the rhizosphere soil of tobacco root knot nematode disease and healthy tobacco plants were collected,and the correlation between soil environmental factors and diseases was explored,which provided a theoretical basis for the monitoring,early warning,prevention and control technology of root knot nematode disease.The main findings are as follows:(1)Whether it was a healthy tobacco plant or an infected tobacco plant,second-stage juvenile nematodes were detected in all root soil samples,indicating that the actual incidence of tobacco plants was not only related to the number of nematodes,but also affected by other microecological environmental factors.At the same time,the number of second-stage juvenile nematodes in the root soil of the diseased tobacco plant was significantly higher than that in the soil of healthy tobacco plant.(2)Compared with the soil of healthy tobacco plants,the soil p H,contents of nitrate nitrogen,alkali-hydrolyzed nitrogen,available potassium,the activities of soil sucrase and acid phosphatase of the root system of the diseased tobacco plant showed different degrees of reduction,among which the p H decreased by 6.71%~16.10%,the nitrate nitrogen content decreased by 48.33%~92.25%,the alkaline hydrolyzable nitrogen content decreased by 25.77%~63.28%,the available potassium content decreased by 31.32%~45.69%,and the sucrase activity decreased by 57.05%~ 157.46%,acid phosphatase activity decreased by 142.03%~717.94%;(3)The differences in microbial community α-diversity between healthy and diseased tobacco rhizosphere soils in different plots were inconsistent,but there were significant differences in the β-diversity of bacteria and fungi in the rhizosphere of diseased and healthy tobacco.The co-occurrence networks showed that the microbial interaction relationship was mainly mutually beneficial,but there were differences between the onset of different plots and the close relationship between the microbial symbiosis network in the healthy soil rhizosphere.The prediction of FUNGuild function showed that the relative abundance of functional fungal types in the rhizosphere soil of the diseased tobacco plant was significantly different from that of the healthy control,and the functional abundance of saprophytic trophic type in the rhizosphere soil of the diseased tobacco plant was significantly higher than that of healthy soil.(4)The overall microbial composition of different treatments is similar,but the relative abundance varies.Compared with healthy tobacco plant rhizosphere soil,the relative abundance of Bacillus,Burkholderia-Caballeronia-Paraburkholderia,Ralstonia,Dyella,Ramlibacter,Aspergillus.,Trichoderma was increased in the rhizosphere soil of susceptible tobacco plants,The relative abundance of Chaetomium,Rhizopus,and Cladosporium decreases.(5)Through upset analysis and random forest analysis,two bacterial taxa(Fibrobacterium,Streptomyces)and six fungal taxa(Herpotrichiellaceae,Sagenomella,Alpine Coedospora,Heterogenea,Microascales and Bisporum sp.)were screened to be associated with the occurrence of root-knot nematode disease.Person correlation analysis showed that bacterial taxa were mainly correlated with available potassium and acid phosphatase,and fungal taxa were mainly significantly correlated with Soil catalase,soil p H and nitrate nitrogen content.