Infecting Analysis Of Tobacco Seeds And Soil Carrying Three Viruses To Tobacco Seedlings

Tobacco belongs to Solanaceae Nicotiana limited annual or perennial herb, is an important economic crop in our country, and the tobacco industry in China's economy also occupies an important place annually for the state and local finances revenue have made a great contribution. Currently, the tobacco mosaic virus, Cucumber mosaic virus and potato virus Y caused by tobacco mosaic virus disease is one of the major diseases in major tobacco growing areas, and it has become the main limiting factor of tobacco production and quality and seriously affected the development of the tobacco industry. In order to clarify the above three viruses in infected tobacco seeds and soil conditions on seedling Infection cases, and to provide reference for tobacco production practice, this research conducted a study of the following aspects. 1. The use of real-time quantitative PCR, the copies of the tobacco disease of the three viruses were quantification. This study was based on positive plasmid clones sequenced after three viruses obtained in the NCBI sequence similarity than the latter in more than 95% of the sequences were designed real-time PCR primers, the plasmid DNA of positive clones was diluted 10-fold gradient 6 as a template to establish a standard curve to determine the reasonableness of the three viruses real-time PCR detection method and reaction conditions, reliability; wherein the copy number of the quantitative tests three other non-viru is TMV:3.72�1010copies/?L,CMV:3.68�1010copies/?L, PVY: 3.76�1010copies/?L.2. Through the use of the known number of copies of the viruses virus sap phosphate buffer soaking seeds in different time periods analyzed nursery Tobacco positive rate of infection. The results showed that after three viruses carrying the seed, Tobacco TMV infection of the strongest, followed by CMV, PVY again; to keep seed virus infection activity time PVY is stronger than TMV and CMV. In this study, levels of virus were used as 3.72�108 copies/?L, 3.68�108copies/?L, after 3.76�108copies/?L virus treated juice, at room temperature for 3 months, no tobacco seedlings detected TMV and CMV, place five months later, a cross of tobacco seedlings in TMV, CMV, PVY three viruses were no detected.3. Defined the three viruses can be infected by the roots of tobacco seedlings. In this study, the virus sap phosphate buffer Baptist roots was found five different concentrations of phosphate buffer virus juice root dip after processing, can make the cross infection of tobacco seedlings three viruses. Wherein the amount of virus respectively 3.72�108 copies /?L, 3.68�108copies/?L, after 3.76�108copies/?L viral juice processing, ELISA positive rate of three viruses, respectively, 40%, 26.67%, 17.78% or more, while the positive rate of RT-PCR to detect the three viruses, respectively, 90%, 30%, 20% or more, which also shows the RT- PCR assay is more sensitive than the ELISA test.4. It has been cleared that PVY can also be spread through the soil in addition to TMV and CMV spread through the soil, but there are differences between the three viruses in the soil survival period in which TMV survived the longest, followed by CMV, PVY shortest survival time.After the preliminary draw viral content of 3.72�108 copies /?L treatment, TMV can survive in the soil for at least 5 months, and CMV and PVY survival time in soil is relatively short. Whether infected nursery substrate after treatment in different time or a different time period breeding large collection of sample Land Nursery, Tobacco Cross of the infected test results are consistent with the virus that is longer in the nursery soil matrix or time, That is, as the longer the virus in the nursery soil matrix or time, three viral infection of Tobacco capacity decreased.In addition, this study had detected symptoms were observed Tobacco experiment found that both seed treatment, seedling root dip or post-processing matrix nursery, in a cross late on Tobacco detected the presence of the virus will show a mosaic symptoms, thus affecting the quality of tobacco leaves. Tobacco law to clear virus infection, which, in particular, is of great significance in terms of plant virus control in actual production practice.