Status Of Occurrence Of Tobacco Virus Disease In Hunan And Screening Of Control Agents

Tobacco viruses are widespread and spread in various and rapid ways,the global tobacco production is affected by it.As an important tobacco producing province in China,huge economic losses has occured in Hunan every year due to the harm of tobacco virus diseases.In this study,tobacco virus diseases in Hunan Province were taken as the research object,the typical symptom samples of tobacco virus diseases were collected in the field.Si RNA sequencing and molecular detection technology were used to identify the species and geographical distribution of tobacco virus diseases.Through field investigation and data analysis,the occurrence and epidemic rules,strains and variation of main virus diseases were explored,and the chemical control agents were screened.The results were as follows:(1)Through si RNA sequencing,it was found that there are 10 kinds of viruses in Hunan tobacco area,namely Tobacco mosaic virus(TMV),Tobacco potato virus Y(PVY),Cucumber mosaic virus(CMV),Tobacco Etch Virus(TEV),Bell pepper mottle virus(BPe MV),Rehmannia mosaic virus(Re MV),Tobacco ring spot virus(TRSV),Pepper mild mottle viru(PMMo V),Tomato masaic virus(To MV)and Tomato mottle mosaic virus(To MMV);the infection was verified by RT-PCR There are 6 kinds of viruses in Hunan tobacco: TMV,CMV,PVY,To MMV,Re MV,PMMo V.Among them,To MMV,Re MV,BPe MV,BPe MV were first discovered in Hunan.There is little difference in the types of virus diseases in the main tobacco producing areas.(2)303 samples were collected from Hunan tobacco areas for virus disease detection,and it was found that the main virus diseases that affected Hunan tobacco areas were TMV,CMV and PVY,and most of them were compound infections;some samples were selected to clone the CP genes of 3 viruses,Variation evolution analysis found that: TMV isolates on Hunan tobacco have a wide range of genetic diversity,and most of the strains are closely related to other Chinese strains;CMV isolates have low variation and low genetic diversity,and are similar to Chinese SD strains.Close genetic relationship,all in the same branch,belonging to subgroup IB of group I,no recombination phenomenon was found in TMV and CMV;PVY isolates are genetically different,they are in different branches,belong to different strain types,and recombination phenomenon Generally,there may be new strain types.(3)The survey of TMV,CMV and PVY infection in the field in Hunan in 2018-2020 found that the infection rate of tobacco viruses was TMV>PVY>CMV.The infection of TMV and CMV began in late March and reached the peak in the middle of June in central and southern Hunan;compared with TMV and CMV,the onset of PVY infection is later,with infection starting in mid-to-early April and peaking in mid-to-late June in central and southern Hunan and starting in mid-to-early May and peaking in mid-to-late July in western Hunan.There was no significant difference in the annual occurrence of the three main viruses among different tobacco growing regions in Hunan.The infection rate of the three major viruses did not vary significantly among five regions.Tobacco in Yongzhou was most seriously infected by TMV,with a maximum infection rate of 16.8%;tobacco in Hengyang was most seriously infected by PVY,with a maximum infection rate of 5.2%;tobacco in Zhangjiajie was most seriously infected by CMV,with a maximum infection rate of 3.0%.(4)The control effects of 8 kinds of tobacco virus diseases were evaluated from the aspects of control effect,yield effect and agronomic traits,the results showed that 20%Moroxydine Hydrochloride WP had relatively good control effect on TMV and CMV,with control effect of 51.68% on TMV and 40.48% on CMV,and had no significant effect on Tobacco Yield and agronomic traits;However,the control effects of these medicaments on PVY were poor.