Robust molecular detection of the new Tomato brown rugose fruit virus in infected tomato and pepper plants from Turkey

Tomato brown rugose fruit virus (ToBRFV) causes severe fruit loss in tomato (Solanum lycopersicum) and pepper (Capsicum annuum) plants. It is an emerging Tobamovirus that is spreading globally. The major challenge is to develop a reliable method for the detection of the virus, and to better characterize the symptoms it causes. The aims of this study, therefore, were to characterize the symptom development on tomato and pepper plants, and to establish a reliable detection method for the virus. Following infection of the tomato and pepper plants with ToBRFV, the leaves turned chlorotic, mosaic or mottled, while the fruit became rugose, necrotic and marbled, and showed discoloration with yellow or brown spots. Transmission electron microscopy (TEM) revealed single rod-like virus particles characteristic of the Tobamoviruses. Classical reverse transcription PCR (RT-PCR) and quantitative PCR (qPCR) with specific primers and probes confirmed that the virus is ToBRFV. We found that the resistance genes from tomato, Tm-22, and pepper, L1, L2, L3 and L4, did not confer resistance to ToBRFV. Here, we present a PCR-based method as a diagnostic test for detecting ToBRFV in infected seeds. This method will help to prevent further spread of the virus in commercial seeds.