Molecular and Biological Characterization of Tomato mottle mosaic virus and Development of RT-PCR Detection

Tomato mottle mosaic virus (ToMMV) was first identified in 2013 as a novel tobamovirus infecting tomatoes in Mexico. In just a few years, ToMMV has been identified in several countries around the world, including the United States. In the present study, we characterized the molecular, serological, and biological properties of ToMMV and developed a species-specific RT-PCR to detect three tomato-infecting tobamoviruses: Tobacco mosaic virus (TMV), Tomato mosaic virus (ToMV), and ToMMV. Previously, ToMMV has been reported in Florida and New York. In this study, we made two new reports on the occurrences of ToMMV on tomatoes in California and South Carolina. Their complete genome sequences were obtained and their genetic relationships to other tobamoviruses evaluated. In host range studies, some differential responses in host plants were also identified between ToMMV and ToMV. To alleviate cross-serological reactivity among the tomato-infecting tobamoviruses, a new multiplex RT-PCR was developed to allow for species-specific detection and identification of TMV, ToMV, and ToMMV. In addition, we observed resistance breaking by ToMMV on selected tomato cultivars that were resistant to ToMV. This has caused serious concerns to tomato growers worldwide. In conclusion, the characterization in molecular and biological properties of ToMMV would provide us with fundamental knowledge to manage this emerging virus on tomato and other solanaceous crops in the U.S. and around the world.