Tobacco Mosaic Virus And Tomato Mosaic Virus Pathogenicity Differences In The Molecular Mechanism Of Research On Tobacco

Tobacco mosaic virus B isolate (TMV-B) and Tomato mosaic virus SI isolate (ToMV-Sl) is two highly related viruses belonging to Tobamovirus with similar genomic organization and function. Interestingly, they cause distinct symptoms in common experimental hosts. TMV can systemically infect Nicotiana tabacum, N. tabacum cv. Burley and N. tabacum cv. Huangmiaoyu with mosaic symptom, while ToMV is localized within inoculated leaf with necrotic lesions. Both TMV and ToMV induced hypersensitive response (HR) and produce necrotic lesions in N. glutinosa, N. tabacum cv. Xanthi (NN), N. tabacum cv. Samsum (NN), and N. edwardsonii, however TMV induce lesions more quickly and the size of lesions are bigger than that of ToMV. The main purpose of this paper is to explain the phenomenon mentioned above and to investigate the function complementation of movement proteins (MPs) between TMV and ToMV.Employing overlap extension PCR technique, the MP gene in TMV-B infectious clone pGEBl? was substituted with ToMV MP gene. To confirm the gene replacement, two pairs of primers specific for TMV and ToMV MP gene were designed and used to identify the recombinant clone pT/OMP. The inserted gene and fusion region sequence was confirmed by sequencing. In vitro transcripts of pT/OMP contain infectivity as pGEBl? and progeny viruses can interact specifically with TMV polyantisera in Western blot assay.To define the interchangeability between the MP function of TMV and ToMV, studies on host range, ability of systemically infection, phenotype of local infection and the salicylic acid (SA) level induced by TMV and T/OMP were conducted.The results show T/OMP and TMV get the same host range. Both of them infect N. tabacum systemically, and induce similar mosaic symptom. The capacity of systemically infection was determined by TAS-ELISA on Samsum (nn), Xanthi (nn), and tomato, no significant difference was found. So the MP gene of ToMV can complement the function of MP gene of TMV in systemic infected hosts and MP gene isvnot the viral factor determining the different phenotype of TMV and ToMV in N.tabacum.In Chenopodium quinoa and C. amaranticolor, TMV and T/OMP induce similar lesions. In N. glutinosa, N. tabacum cv. Xanthi (NN), N. tabacum cv. Samsum (NN), and N. edwardsonii, the lesion size and lesion external brown ring, induced by T/OMP are smaller than that of TMV. This suggests that MP gene affect the lesion size produced during N-mediated HR.In N. glutinosa, N. tabacum cv. Xanthi (NN), and N. edwardsonii, T/OMP and ToMV induce similar lesions. But in Samsum (NN) tobacco, lesions induced by T/OMP are bigger than that of ToMV.The concentration of SA induced by TMV and T/OMP is related with lesion size at 108h and 120h postinoculation, and more experiments are being done.