The Varieties,Occurrence And Prevention Of Virus In Yibin Tobacco Region

Tobacco is an important cash crop,and its economic benefits are seriously affected by virus diseases.The species and strains of virus were identified in Yibin tobacco region of Sichuan province.The genetic structure of Tobacco vein band mosaic virus was analyzed.The occurrence and epidemic regularity of the major viral diseases were investigated and analyzed,to identify the key factors affecting the occurrence and epidemic of local tobacco viral diseases.At the same time,field control research was carried out.The conclusions are as follows: 1.Species and strains identification of virus in Yibin tobacco regionIt is clear that the main virus are Tobacco mosaic virus,Cucumber mosaic virus,Potato Y virus and Tobacco vein band mosaic virus through the general survey and detection of virus in Yibin tobacco region.TMV is distributed in all tobacco regions,which is the main virus.By constructing the phylogenetic trees,TMV belong to group I,CMV subgroup I is the local dominat strains,PVY belong to O strains,TVBMV and the isolates of Yunnan and Guizhou province were clustered in the same branch which belong to SW group.2.Genetic structure of Tobacco vein band mosaic virusIn this study,the recombinant analysis of 18 complete genome sequences showed that TVBMV has more frequent intraspecific recombination,and the recombination hotspots are distributed in the fragments of HC-Pro and CI.Through the evolution analysis of 70 TVBMV CP genes,the isolates of Yunnan,Sichuan and Guizhou were divided into SW groups.At the same time,SW group and MC group had strong TVBMV-geographic correlation.Further analysis indicates that the spatial genetic structure of the TVBMV population may be caused by population genetic structure and natural selection.TVBMV in China originated fromYunnan by MCC tree analysis.Bayesian spatial dynamics analysis shows that Shandong and Yunnan play an important role in the prevalence of TVBMV.The TVBMV CP gene was negatively selected,and the MC group of isolates received significant positive selection pressure at the first and third amino acid positions of the CP gene.3.The occurrence and epidemic of virus disease in Yibin tobacco regionThrough a comprehensive investigation on the occurrence and prevalence of virus disease in Yibin tobacco region,it is clear that the local tobacco planting model and winter management model are important factors to affect the occurrence and epidomic of local virus disease.TMV was detected almost in all soil samples.Meanwhile,with the continuous increase of planting years,TMV in soil increased,which lead to more serious virus disease.4.Prevention and control of virus diseasesWe selected two experimental location which on the middle and high altitude areas of Yibin tobacco region.The experimental fields were set up for the experiment of virus control.We screened some agents,including the virus inhibitors: octyl alkyl ammonia,pyrimethoprim guanidine;plant resistance inducer: brassinolide;biocontrol microorganism: Polymyxomycosis and Bacillus cereus.The compound treatment of these agents improved the control effect on virus.