A tomato mottle mosaic virus-based vector system for gene function studies in tomato

Plant virus-based vectors provide a convenient tool for rapid protein expression and gene function studies. However, there is little research on viral vectors capable of systemically expressing proteins in tomatoes. Here, we substituted the coat protein (CP) gene with GFP gene in a previously constructed tomato mottle mosaic virus (ToMMV; genus Tobamovirus) infectious clone pCBToMMV to produce transiently expressing vectors, which could express GFP in the infiltrated leaves of Nicotiana benthamiana plants. We then inserted the sub-genomic promoter and CP gene from another tomamovirus tomato mosaic virus downstream of GFP gene to form a vector capable of systemically expressing GFP in both N. benthamiana and Solanum lycopersicum plants. The ToMMV-based vector also expressed the MYB-related transcription factor Rosea1, inducing anthocyanin biosynthesis in the systemic leaves of both N. benthamiana and S. lycopersicum plants. Additionally, expressing the bialaphos resistance gene using the ToMMV vector conferred resistance to the herbicide glufosinate-ammonium in plants. Furthermore, the ToMMV vector successfully expressed a 68 kDa β-glucuronidase in systemic leaves and roots of N. benthamiana and S. lycopersicum plants. This ToMMV-based vector provides a simple and efficient tool for gene function studies in tomatoes.