Green fluorescent protein (GFP)-tagged viruses are basic research tools widely applied in studies concerning molecular determinants of disease during virus infection. Here, we described a new generation of genetically stable infectious clones of tomato torrado virus isolate Kra (ToTVpJL-Kra) that could infect Nicotiana benthamiana and Solanum lycopersicum. Importantly, a modified variant of the viral RNA2-with inserted sGFP (forming, together with virus RNA1, into ToTVpJL-KraGFP)-was engineered as well. RNA2 of ToTVpJL-KraGFP was modified by introducing an additional open reading frame (ORF) of sGFP flanked with an amino acid-coding sequence corresponding to the putative virus protease recognition site. Our further analysis revealed that sGFP-tagged ToTV-Kra was successfully passaged by mechanical inoculation and spread systemically in plants. Therefore, the clone might be applied in studying the in vivo cellular, tissue, and organ-level localization of ToTV during infection. By performing whole-plant imaging, followed by fluorescence and confocal microscopy, the presence of the ToTVpJL-KraGFP-derived fluorescence signal was confirmed in infected plants. All this information was verified by sGFP-specific immunoprecipitation and western blot analysis. The molecular biology of the torradovirus-plant interaction is still poorly characterized; therefore, the results obtained here opened up new possibilities for further research. The application of sGFP-tagged virus infectious clones and their development method can be used for analyzing plant-virus interactions in a wide context of plant pathology.
Keywords: infectious clone; plant pathology; plant-virus interaction; sGFP; tomato torrado virus.