Distribution and molecular variability of four tobacco viruses in China

Dear Editor,Plant viruses cause great economic losses to tobacco production(Dai et al.,2012).Many types of viruses have been reported to infect tobacco plants,including Tobacco mosaic virus(TMV)(Chen et al.,2014),Cucumber mosaic virus(CMV)(Dai et al.,2012),Tobacco

Dear Editor, Plant viruses cause great economic losses to tobacco pro- duction （Dai et al., 2012）. Many types of viruses have been reported to infect tobacco plants, including To- bacco mosaic virus （TMV） （Chen et al., 2014）, Cucum- ber mosaic virus （CMV） （Dai et al., 2012）, Tobacco etch virus （TEV） （Legnani et al., 1996）, Potato virus Y （PVY） （Dai et al., 2012）, Tobacco ringspot virus （TRV） （Zellner et al., 2011）, and Tobacco vein banding mosaic virus （TVBMV） （Wang et al., 2010）. TMV, CMV, TEV, and PVY are those four plant viruses that are considered the most serious causative agents of diseases in tobacco plants in China （Dai et al., 2012; Chen et al., 2014; Zhao et al., 2015）. In China, these tobacco viruses have been found in 16 provinces, including the Yunnan, Hunan, Henan, Fujian, Shaanxi, Shandong, and Liaoning provinces （Chen et al., 1997）. These viruses have very high mutation rates during replication because their RNA polymerases lack the proofreading ability. Consequently, these viruses exist as numerous strains and replicate as complex and dynamic mutant clusters （Elena et al., 2005）. Therefore, understanding the distribution, genetic diversity, and evolutionary relationships of these viruses is a fundamentally important step in controlling these viruses.