First report of <i>Tomato brown rugose fruit virus</i> in tomato in Switzerland

In Switzerland, greenhouses for tomato (Solanum lycopersicum) production are inspected systematically Tomato brown rugose fruit virus (ToBRFV) in accordance with phytosanitary regulations, by sampling symptomatic plants during routine visits. July 2021, a suspected viral disease was reported from an 8-hectare greenhouse the canton of Thurgau eastern on single plant soil-grown crop (cv. Dubino). This exhibited light discoloured spots which were unusual this variety and rather reminiscent symptoms associated Pepino mosaic (PepMV) infection. Transmission electron microscopy observation leaf-dip preparations showed mixture filamentous, potexvirus-like particles likely corresponding to mild PepMV isolate used cross-protection few months earlier, as well rod-shaped, tobamovirus-like structures (Figure 1). RT-qPCR analyses using ToBRFV-specific primer sets CaTa28 CSP1325 (International Seed Federation, 2020) gave strong positive results Cq values 8.4 10.8, respectively. The presence further confirmed conventional RT-PCR ToBRFV-F/-R primers Alkowni et al. (2019). Blastn analysis amplicon sequence revealed 100% identity number ToBRFV sequences including Tom1-Jo Jordan (GenBank Accession No. NC_028478.1). Total dsRNA extracted infected material according Mahillon (2021) subsequently sent high throughput sequencing NovaSeq 6000 platform. A complete genome (6386 nt; OM305070) assembled obtained reads shared 99.8% nt ToBRFV-IL (KX619418.1). 6412 also 99.9% PepMV-P12-3G (MK133092.1). No other identified. parallel, sap inoculation Nicotiana tabacum cv. Xanthi induced typical necrotic local lesions visible seven dpi 2). is first report Switzerland. 1670 leaf samples asymptomatic sampled between 12 21 2021 at their apex (analysed pools 10 plants) all areas greenhouse. Furthermore, four root taken rows adjacent initial positive. After removal plants, cleaning infrastructure steam disinfection soil, surface 245 cotton swabs titre collected packing machines, scissor lifts overhead heaters. Therefore, additional performed, followed commercial benzoic acid (MENNO Florades) before second analysis. total 2% soil remained weakly Consequently, 2022 will switch entirely hydroponics order reduce risk outbreak restarting debris soil. site be monitored next two seasons ensure effectiveness eradication measures implemented.