Poster Session: Virology

137-P

Genome characterization of Tomato necrotic dwarf virus, a Torradovirus from southern California.
W. M. WINTERMANTEL (1), L. L. Hladky (1)
(1) USDA ARS, Salinas, CA, U.S.A.

Tomato necrotic dwarf virus (ToNDV) is a whitefly-transmitted virus that caused significant losses for tomato production in southern California during the 1980s, but was never fully characterized. The virus produces icosahedral virions approximately 30 nm in diameter, and can be transmitted by three whitefly species; Bemisia tabaci, Trialeurodes abutilonea, and T. vaporariorum, as well as mechanically and by grafting. Symptoms and transmission characteristics of ToNDV resemble those of other members of the emerging genus, Torradovirus, family Secoviridae. An isolate of ToNDV originally collected from Imperial County, CA and maintained in tomato was sequenced to determine its relationship to other viruses. The ToNDV genome is composed of two RNA molecules of 7.2 and 4.9 kb. RNA1 contains a large ORF encoding a 2150 aa polyprotein that has homology to other viruses within the genus, Torradovirus. RNA2 encodes two ORFs of 189 and 1190 aa, respectively, with the latter expressed as a polyprotein. The closest relative of ToNDV is Tomato marchitez virus at 80% and 91% identity for the RNA1 and RNA2 polyproteins, respectively. Sequence identity for other members of the genus range from 62-81% for the RNA1, and 69-83% for the RNA2 polyproteins. Results of sequence analysis and comparison of genomic and biological features confirm ToNDV should be recognized as a distinct member of the genus Torradovirus.