Genome sequence, host range, and whitefly transmission of the torradovirus Tomato necrotic dwarf virus

W.M. Wintermantel, L.L. Hladky, A.A. Cortez
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. Previous studies demonstrated transmission by Bemisia tabaci as well as mechanically and by grafting, and current studies have demonstrated transmission by Trialeurodes abutilonea and Trialeurodes vaporariorum. Whitefly transmission by T. abutilonea was slightly better than by T. vaporariorum. Tomato is the primary crop affected by ToNDV, but the virus can efficiently infect other members of the Solanaceae. Symptoms and transmission characteristics of ToNDV resemble those of viruses in the emerging genus Torradovirus, family Secoviridae. An isolate of ToNDV originally collected from Imperial County, California, 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 2151 aa protein that has homology to that of other viruses within the genus, Torradovirus. RNA2 encodes two ORFs, of 190 and 1191 aa, 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 identities to other members of the genus range from 62-81% for the RNA1 and 69‑83% for the RNA2 polyproteins. An infectious clone of ToNDV has been developed for further biological characterization of the virus.
Wintermantel, W.M., Hladky, L.L. and Cortez, A.A. (2018). Genome sequence, host range, and whitefly transmission of the torradovirus Tomato necrotic dwarf virus. Acta Hortic. 1207, 295-302
DOI: 10.17660/ActaHortic.2018.1207.41
Bemisia, infectious clone, Secoviridae, Solanum lycopersicum, Trialeurodes

Acta Horticulturae