First report of Tomato brown rugose fruit virus infecting greenhouse tomato in the U.S.

Authors: Ling, Kai-Shu; TIAN, TONGYAN - California Department Of Food And Agriculture; GURUNG, SURAJ - Sakata Seed America, Inc; SALATI, RAQUEL - Eurofins Biodiagnostics; Gilliard, Andrea

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/22/2019
Publication Date: 3/7/2019
Citation: Ling, K., Tian, T., Gurung, S., Salati, R., Gilliard, A.C. 2019. First report of Tomato brown rugose fruit virus infecting greenhouse tomato in the U.S. Plant Disease. 103:1439. https://doi.org/10.1094/PDIS-11-18-1959-PDN.
DOI: https://doi.org/10.1094/PDIS-11-18-1959-PDN

Interpretive Summary: Tomato is an important vegetable crop growing around the world. The U.S. is ranked second in the world on tomato production, with over $2 billion farm gate values annually. With an increasing trend in greenhouse tomato production, serious disease outbreaks have been shown to be induced by a number of seed-borne and mechanically transmitted viruses. In this study, in collaboration with industry pathologists, ARS scientist in Charleston, SC conducted appropriate biological, serological and molecular analysis to identify Tomato brown rugose fruit virus (ToBRFV) as the causal agent for recent disease outbreaks on greenhouse tomato in southern California, USA as well as in Baja California, Mexico. ToBRFV was first identified in 2014 and currently has only been reported in Jordan and Israel. This is the first report of ToBRFV infecting greenhouse tomatoes in North America. The ability of ToBRFV to break the resistance Tm2^2 gene in tomato, raises serious concerns to the tomato industry. How ToBRFV was introduced to the U.S. and/or Mexico has not been determined. Eradication efforts are underway in both countries to contain and control these disease outbreaks.

Technical Abstract: Tomato (Solanum lycopersicum L.), an important vegetable widely grown in the world, is susceptible to a number of emerging viruses. In September 2018, a severe disease outbreak, including mosaic, mottling and plant stunting was observed on grafted tomato plants in a greenhouse facility (~8 acres) in southern California, USA. Initial screening to one symptomatic sample was positive for Pepino mosaic virus (PepMV) and to a tobamovirus (cross reaction to Tomato mosaic virus (ToMV) using ELISA). Two types of viral particles, including flexuous potexvirus-like and rigid tobamovirus-like particles were observed under an electron microscope. Through additional screening using polymerase chain reaction and sequencing, Tomato brown rugose fruit virus (ToBRFV) was positively identified. Based on additional analysis of 20 samples collected in the same greenhouse, incidence of ToBRFV infection was estimated to be in 70%. In a separate survey in October 2018, a similar disease outbreak on tomato was also observed in a major greenhouse facility in Baja California, Mexico. A mixed infection of multiple viruses were identified. ToBRFV was identified to be wide-spread in this greenhouse as all 14 samples tested were positive. The two isolates of ToBRFV, from the U.S. (ToBRFV-US) and Mexico (ToBRFV-MX) were similar in sequence (99.6% sequence identity). ToBRFV was first identified in 2014 and currently has only been reported in Jordan and Israel. This is the first report of ToBRFV infecting greenhouse tomatoes in North America. The ability of ToBRFV to break the Tm2^2 resistance gene in tomato, raises serious concern to the tomato industry. How ToBRFV was introduced to the U.S. and/or Mexico has not been determined. Eradication efforts are underway in both countries to contain and control these disease outbreaks.