Comprehensive Sampling and Detection Strategies for the Field Surveillance of Tomato Brown Rugose Fruit Virus

Tomato brown rugose fruit virus (ToBRFV) poses a significant threat to tomato production. Effective and accurate detection is critical for limiting the introduction and spread of ToBRFV. In this study, the impact of tomato planting patterns, growth stages, and cultivar variability on ToBRFV levels in tomatoes from distinct greenhouses and open fields were comprehensively analyzed. The results indicated that ToBRFV is detectable in asymptomatic tissues, regardless of artificial agroinoculation or natural infection. Additionally, higher viral levels were observed in newly emerging leaves and in fruits and sepals compared to old leaves. For tomato fruits infected with ToBRFV, the viral level in the mesocarp is higher than in the other interior parts, and no correlation was found between viral levels and the color of fruit lesions. Based on these results, it is recommended that new leaves and sepals should be given priority for testing of ToBRFV from tomato seedlings to the color turning stage, and that fruits and sepals are suggested to be collected at the full ripeness stage of tomato plants. This study underscores the importance of regular detection and optimal sampling beyond symptom observation in the surveillance of ToBRFV.