Tomato Brown Rugose Fruit Virus Pandemic.

Tomato brown rugose fruit virus (ToBRFV) is an emerging tobamovirus. It was first reported in 2015 in Jordan in greenhouse tomatoes and now threatens tomato and pepper crops around the world. ToBRFV is a stable and highly infectious virus that is easily transmitted by mechanical means and via seeds, which enables it to spread locally and over long distances. The ability of ToBRFV to infect tomato plants harboring the commonly deployed Tm resistance genes, as well as pepper plants harboring the L resistance alleles under certain conditions, limits the ability to prevent damage from the virus. The fruit production and quality of ToBRFV-infected tomato and pepper plants can be drastically affected, thus significantly impacting their market value. Herein, we review the current information and discuss the latest areas of research on this virus, which include its discovery and distribution, epidemiology, detection, and prevention and control measures, that could help mitigate the ToBRFV disease pandemic.

Isolation and molecular characterization of a tomato brown rugose fruit virus mutant breaking the tobamovirus resistance found in wild Solanum species.

A new tobamovirus named tomato brown rugose fruit virus (ToBRFV) overcomes the effect of the Tm-1, Tm-2, and Tm-22 resistance genes introgressed from wild Solanum species into cultivated tomato (Solanum lycopersicum). Here, we report the isolation and molecular characterization of a spontaneous mutant of ToBRFV that breaks resistance in an unknown genetic background, demonstrated recently in Solanum habrochaites and Solanum peruvianum. The wild isolate ToBRFV-Tom2-Jo and the mutant ToBRFV-Tom2M-Jo were fully sequenced and compared to each other and to other ToBRFV sequences available in the NCBI GenBank database. Sequence analysis revealed five nucleotide substitutions in the ToBRFV-Tom2M-Jo genome compared to ToBRFV-Tom2-Jo. Two substitutions were located in the movement protein (MP) gene and resulted in amino acid changes in the 30-kDa MP (Phe22 → Asn and Tyr82 → Lys). These substitutions were not present in any of the previously described ToBRFV isolates. No amino acid changes were found in the 126-kDa and 183-kDa replicase proteins or the 17.5-kDa coat protein. Our data strongly suggest that breaking the newly discovered resistance in wild tomatoes is associated with one or two mutations on the MP gene of ToBRFV.

Screening of Solanum (sections Lycopersicon and Juglandifolia) germplasm for reactions to the tomato brown rugose fruit virus (ToBRFV).

The reaction of 636 Solanum (sections Lycopersicon and Juglandifolia) accessions were evaluated under greenhouse conditions after mechanical inoculation with a Jordanian isolate of the new tobamovirus tomato brown rugose fruit virus (ToBRFV). Local and systemic infections were assayed by symptoms evaluation and virus detection via biotests and RT-PCR. All cultivated tomatoes (Solanum lycopersicum) and the great majority of wild tomato accessions proved susceptible to ToBRFV. They showed a wide range of symptoms (mosaic, leaf deformations, mottling, shoestring, and stunting). Twenty-six accessions representing S. lycopersicum var. cerasiforme, S. pimpinellifolium, S. habrochaites, and S. chilense were tolerant. High levels of resistance have been demonstrated in three accessions of S. ochrantum, a close relative to wild tomatoes (member of the sect. Juglandifolia) not only to ToBRFV but also to the tobamoviruses, tobacco mosaic virus (TMV) and tomato mosaic virus (ToMV). After mechanical inoculation, the three tobamoviruses could be detected only in inoculated leaves in the accessions LA2160, LA2162, and LA 2166, which remained symptomless. However, two other S. ochrantum accessions PI 473,498 and PI 230,519 reacted unusually. They were demonstrated highly resistant to TMV and ToMV, but proved transiently susceptible to ToBRFV showing mild systemic mosaic followed by total recovery from symptoms and the virus. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s41348-021-00535-x.