| Tobacco?Nicotiana tabacum L?is an important commercial crop.Tobacco virus disease brings serious economic losses to the tobacco industry.Among them,tobacco mosaic virus,cucumber mosaic virus,potato virus Yare most seriously endangered.In recent years,the proportion of two or more viruses complex infection has been increasing in tobacco fields.Tobacco field soil with TMV,CMV and PVY is an important factor leading to tobacco virus to-icity.In order to establish a high-efficiency method for soil virus detection in tobacco fields,a series of studies were conducted to find out the mechanism of interaction of multiple viruses in tobacco.The main results are as follows:1.In this study,a perfect virus detection system for tobacco field soil was established.The TMV,CMV and PVY in the soil of tobacco field could be detected effectively by using ELISA,RT-PCR,realtime fluorescence quantitative RT-PCR and RT-LAMP.The method of using ELISA,RT-PCR,realtime fluorescence quantitative RT-PCR and RT-LAMP detection sensitivity of TMV were 10-3g soil/mL,10-3,10-5and soil 10-6;sensitivity of four methods for detection of CMV were 10-1 g soil/mL,10-1,10-3 and soil 10-4;sensitivity of four methods for detection of PVY were 10-2g soil/mL,10-2,10-4 and 10-5.2.The distribution and content of three major viruses in tobacco were different in different positions of soil.The distribution of TMV and PVY is the most widely distributed and the CMV is the least.With the increase of vertical distance and horizontal distance of tobacco roots,the content of virus in soil decreased gradually.With the increase of tobacco planting time,the accumulation and diffusion capacity of virus in soil increased.With the increase of tobacco planting time,the accumulation and diffusion capacity of virus in soil increased.The virus content in tobacco continuous cropping soil was higher than that in tobacco and rice rotation soil.3.In the composite infection of TMV and CMV,CMV interfered with the expression of CP,MP,p-183 and p-126 genes in TMV.TMV has synergistic effects on CMV and promotes the expression of CMV,2b genes,CP genes,MP genes and Rep genes.This interference or synergistic effect reached an upward or downward inflection point at 30 days of inoculation.In the comple-infection of TMV,CMV and PVY,PVY interferes with CMV,mainly inhibiting the expression of CMV,2b gene,CP gene,MP gene and Rep gene.PVY plays a synergistic role in TMV,which is mainly involved in promoting the expression of MP and p-183 genes in TMV.21 days after compound infection,the interference of PVY on TMV co production and CMV to TMV was gradually reached,and the two effects gradually reached equilibrium.From the 14 days of compound infection,the interference of PVY to CMV and the synergistic effect of TMV on CMV gradually reached equilibrium.The interference effect of PVY on CMV was stronger than that of TMV on CMV in 2130 days.In the process of complex infection,TMV and CMV seriously interfered and even inhibited the gene expression of PVY.The completion of the above work is of great significance for understanding the transmission route and interaction mechanism of tobacco virus in tobacco,making effective measures,preventing and controlling viral diseases and reducing economic losses. |
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