Identification And Integrated Control Technigues On Tobacco Virus Diseases In Luzhou City

Luzhou city is the main growing area of tobacco in Sichuan Province.The planting area of tobacco is about 100,000 acres,and the harvest of tobacco leaves is about 10,00,0000 kg every year.As the main disease,viral disease often affects the development of tobacco planting area.Tobacco virus disease has become one of the main limiting factors for tobacco production in Luzhou.It is of great significance to clarify the species and distribution of major viral diseases and construct a integrated management system for tobacco virus disease in Luzhou tobacco area.In the stages of seedlings,stages of rosette,prosperously growing stage and mature stages of tobacco,several samples of suspected viral diseases,such as mosaic,deformity,lightning plaque,pulse necrosis,etching,and ring spot,were collected at various of tobacco stations in Xuyong County and Gulin County of Luzhou City,Sichuan Province.The collected samples were detected by reverse transcription polymerase chain reaction(RT-PCR)using universal primers of Tobamovirus,Potyvirus,CMV and TSWV.Samples with the detected bands were amplified and the PCR products were cloned into the T-vector.After the verification of colony PCR,the plasmids were extracted and subsequently sequenced.The sequences obtained were aligned by BLAST in NCBI database.It was found that there were 6 tobacco viruses existing in the tobacco area of Luzhou,including Tobacco mosaic virus(TMV),Cucumber mosaic virus(CMV),Potato virus Y(PVY),Potato virus A(PVA),and Tobacco vein banding mosaic virus(TVBMV)and Chilli veinal mottle virus(Chi VMV).Among these,TMV had the widest distribution in the two counties,which was the main virus infecting tobacco in Luzhou.Moreover,PVY widely occurred in Gulin,while CMV,PVA,and TVBMV and Chi VMV had a small distribution and sporadic occurrence.It has not been reported that Chi VMV infected tobacco in Sichuan Province,it infecting tobacco was only reported in Yunnan province and this is the first reported on its emergence.This article has conducted an in-depth study on Chi VMV.The full-length sequence of Chi VMV was amplified by RT-PCR and rapid amplification of c DNA ends(RACE),and a 9726-bp full-length sequence(Gen Bank number:MK 405594)was obtained.Through analysis of the sequence and phylogenetic tree,it was showed that the sequence was closely related to that of Chi VMV-Yp8 and Chi VMV-Pp4,two isolates from pepper in Sichuan,with more than 98% identity of the amino acid and nucleotide sequence.After differential host reaction,the obvious symptoms were observed and Chi VMV could be detected in Lycopersicon esculentum,Nicotiana tabacum,Capsicum annuum,Physalis floridana and Nicotiana glutionsa except for Nicotiana glutionsa.The screen of high-efficiency antiviral pesticide was carried out in Luzhou tobacco area.Spray treatment was performed on tobacco in the stages of seedling and field,respectively.The application was repeated twice,and the results showed that 1000 times solution of 6% oligosaccharide · chain protein and 1000 times liquid of 8% Ningnanmycin had a better antiviral effect in the field.However,there was no significant difference in prevention effect among selected agents.Based on the results of above research contents,combined with the actual ecological environment of Luzhou tobacco area,aiming at the characteristics of viral disease in Luzhou tobacco area,the integrated control technology system of tobacco virus disease in Luzhou area was established: prevention and control of TMV and PVY were the mainstay,and controlling source of viruses was strengthened;blocking the insect transmission of CMV,PVY and other viruses;using non-viral seedling production technology,blocking insect vector transmitting technology,immuno-induced resistance technology as the main technical basis,combined with agricultural control,ecological engineering control,forecasting and early warning,and precise application of pesticides as several integrated prevention and control points,series of operating instructions have been introduced,including the preparation work before planting,the precautions of various operations in the planting process,and the centralized processing after harvesting.The implementation of integrated management technologies could reduce the risk and damage of viral diseases in tobacco area of Luzhou.