Directions from Nature: How to Halt the Tomato Brown Rugose Fruit Virus

Abstract

Tomato brown rugose fruit virus (ToBRFV) is a recently emerged serious viral threat to tomato production. The virus is named after its symptoms consisting of characteristic brown wrinkled (rugose) patches on the fruits of infected tomato plants. ToBRFV is a member of the genus Tobamovirus and a very stable mechanically transmitted virus. So far, most tomato cultivars are susceptible, enabling a swift spread of ToBRFV. In this review, we present strategies to halt devastating disease outbreaks of ToBRFV based on the collective research data of various tobamovirus–plant interactions. Viruses, like ToBRFV, are biotrophic pathogens with small genomes. Hence viral proliferation depends on various host factors, also termed susceptibility (S) genes. However, S genes often have an intrinsic function for the host plant. Thus, mutations in S genes may lead to pleiotropic phenotypes. Therefore, identifying mutant variants of S genes with no pleiotropic effects is essential for exploring impaired S genes in breeding tomatoes resistant to ToBRFV.