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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » National Germplasm Resources Laboratory » Research » Publications at this Location » Publication #359703

Research Project: Characterizing and Detecting Pathogens to Ensure Safe Exchange of Plant Germplasm

Location: National Germplasm Resources Laboratory

Title: Characterization of Tomato necrotic spot virus, a subgroup 1 ilarvirus causing necrotic foliar, stem, and fruit symptoms in tomatoes in the United States

item BRATSCH, SARA - University Of Minnesota
item Grinstead, Sam
item CRESWELL, TOM - Purdue University
item RUHL, GAIL - Purdue University
item Mollov, Dimitre

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/27/2019
Publication Date: 5/8/2019
Citation: Bratsch, S., Grinstead, S.C., Creswell, T., Ruhl, G., Mollov, D.S. 2019. Characterization of Tomato necrotic spot virus, a subgroup 1 ilarvirus causing necrotic foliar, stem, and fruit symptoms in tomatoes in the United States. Plant Disease.

Interpretive Summary: Tomato is the highest value vegetable crop grown in the U.S. In 2017 and 2018 tomatoes from Indiana and Ohio exhibited necrotic spots on leaves and necrotic streaks on stems. Fruits had scabbing, necrotic spots and lines that made them unmarketable. Healthy plants were inoculated with sap from symptomatic leaves. The inoculated plants developed the same symptoms and virus infection was subsequently confirmed. The virus was identified as tomato necrotic spot virus (ToNSV). The complete genomic sequence of ToNSV was determined. Based on phylogenetic analysis and genomic sequence comparisons to known viruses, ToNSV was characterized as a member of the genus Ilarvirus, family Bromoviridae. The completion of the ToNSV genome sequence facilitates developing reliable detection methods and better control measures of this newly described virus. This information will be useful to the vegetable industry, plant diagnosticians and regulatory agencies.

Technical Abstract: The genomic, biological, and serological characterization of tomato necrotic spot virus (ToNSV), a virus first described infecting tomato in California, was completed. The complete genomic sequence identified ToNSV as a new subgroup 1 ilarvirus distinct from the previously described tomato-infecting ilarviruses. We identified ToNSV in Indiana in 2017 and 2018 and in Ohio in 2018. The coat protein coding region of the isolates from California, Indiana, and Ohio have 94-98% identity while the same isolates had 99% amino acid identity. ToNSV is serologically related to TSV, a subgroup 1 ilarvirus, and shows no serological relationship to ilarviruses in the other subgroups. In tomato, ToNSV caused symptoms of necrotic spots and flecks on leaves, necrotic streaking on stems, and necrotic spots and circular patterns on fruit while Nicotiana glutinosa plants were asymptomatic. These results indicate that ToNSV is a proposed new subgroup 1 ilarvirus causing a necrotic spotting disease of tomato observed in California, Indiana, and Ohio.