Transmission rate of two Polish Tomato torrado virus isolates through tomato seeds

Efficient dispersion of Tomato torrado virus (ToTV), an emerging virus affecting tomato crops worldwide, is linked to its principal vectors, Bemisia tabaci and Trialeurodes vaporariorum. To evaluate whether ToTV can be seed-transmitted, we collected seeds from tomato varieties Beta Lux, Grace and Money Maker that had been mechanically inoculated with two ToTV isolates; seedlings were grown in an insect-proof glasshouse, then tested for ToTV by immunocapture-qRT-PCR. Among 17,985 plants, 69 were ToTV-positive (0.38% overall vertical transmission). Bioassays using indicator plants confirmed the presence of infectious virus in the seedlings. This is the first report of tomato seed transmission of ToTV.