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[Objective] The pmpose of this paper is to obtain the basis information of Potyviruses distribution and investigate Potyvirus species between resistant and susceptible tobacco varieties to PVY in field in Yunnan Province. [Method] During 2017 to 2019,497 tobacco samples with typical Potyviral symptoms were collected in 5 cities, 13 tobacco planting counties (districts) in Yunnan Province and the types of Potyviruses on the main susceptible and resistant varieties to PVY were analyzed. [Result] The results showed that 85. 1 % of 497 tobacco samples were infected by Potyviruses in total. Furthermore, the detection rates of TVBMV, ChiVMV, PVY, and TEV were 58. 8 %, 23. 3 %, 14. 9% and 7. 8% respectively. In terms of the rank of detection rates of Potyviruses in the PVY susceptible varieties, the detection rate of TVBMV was the highest in Qujing,and for ChiVMV was in Yuxi,and for PVY was in Zhaotong. The PVY detection rate on the PVY-resistance varieties was 5. 8% around and much lower than that of susceptible varieties (22. 5%). PVY resistant varieties showed a good crop protection for the PVY disease. [ Conclusion] The analysis showed that the resistant varieties which contained va locus dramatically reduced the yield loss in the high incidence areas of PVY, and the increase of TVBMV detection rate in PVY resistant varieties was due to the decrease of PVY incidence rate, and the resistant varieties did not increase the harm of TVBMV and ChiVMV. However, the single va resistant locus had no effect on the TVBMV and ChiVMV. Therefore, the investigation of Potyviruses species should be carried out before introduce va-containing varieties into the area. TVBMV and ChiVMV had been the emerging disease in Yunnan's main tobacco growing areas, resulting in low yield and quality loss. It is necessary to establish new method to detect these causal agents and to screen moreresistant germplasm resources for TVBMV and ChiVMV. [ABSTRACT FROM AUTHOR]

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