Biological Characteristics of Cucumber Mosaic VirusSubgroupⅠfrom Tobacco

Cucumber mosaic virus (CMV) showing heavy narrow mosaic and enation deformity on tobacco leaf was isolated. The strain, viral morphology, pathogenicity, dilution limit concentration, transmission route and symptoms on resistant and susceptible tobacco were studied via biological inoculation, CP gene sequencing, electron microscopy, western blot and qRT-PCR. The results showed that the 657 bp coat protein gene shared 69.83% homology to CMV group Ⅱof Q strain, 93.00% identity to CMV groupⅠof Fny strain, which were between ⅠA andⅠB strains. The virus particles were spherical, about 28-30 nm in diameter. It showed strong pathogenicity to tobacco. The dilution limit concentration of disease juice was 10^-5 in vitro. After inoculation with 40 times dilution on tobacco, CMV systemically spread from inoculated leaf to stem, first down to root and up to heart leaf, then to whole plant, finally continued to upper new leaves. Bright yellow and G28 were susceptible, showing heavy narrow and yellow mosaic, leathery and distorted leaves. Ti245 and Tiepazi were moderate resistance, showing vein clearing and mild mosaic.