Phylogenetic relationships of closely related potyviruses infecting sweet potato determined by genomic characterization of Sweet potato virus G and Sweet potato virus 2
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Complete nucleotide sequences of Sweet potato virus G (SPVG) and Sweet potato virus 2 (SPV2) were determined to be 10,800 and 10,731 nucleotides, respectively, excluding the 3′-poly(A) tail. Their genomic organizations are typical of potyviruses, encoding a polyprotein which is likely cleaved into 10 mature proteins by three viral proteinases. Conserved motifs of orthologous proteins of viruses in the genus Potyvirus are found in corresponding positions of both viruses. Pairwise comparisons of individual protein sequences of the two viruses with those of 78 other potyviruses show that P1 protein and coat protein (CP) of both viruses are significantly large, with the SPVG CP as the largest among the all the known species of the genus Potyvirus. The extended N-terminal region of the P1 protein is conserved in the potyviruses and ipomovirus infecting sweet potato. A novel ORF, PISPO, is identified within the P1 region of SPVG, SPV2, Sweet potato feathery mottle virus (SPFMV), and Sweet potato virus C (SPVC). The C-terminal half of CP is highly conserved among SPFMV, SPVC, SPVG, SPV2, and Sweet potato virus-Zimbabwe. Phylogenetic analysis based on the deduced CP amino acid sequences supports the view that these five viruses are grouped together in a SPFMV lineage. The analysis also reveals that Sweet potato virus Y and Ipomoea vein mosaic virus are grouped with SPV2 as one species, and these two viruses should be consolidated with SPV2.
KeywordsSweet potato virus G Sweet potato virus 2 Potyvirus Genomic sequence PISPO Phylogeny
The authors thank Whitney Hymes, Crindi Loschinkohl, and Sam Grinstead for their providing the excellent technical assistance; Drs. Joseph Foster, John Hartung, Hsing-Yeh Liu, and Gary Kinard are also thanked for their critical review of the manuscript.
- 2.M.J. Adams, F.M. Zerbini, R. French, F. Rabenstein, D.C. Stenger, J.P.T. Valkonen, in Virus Taxonomy, ed. by A.M.Q. King, E. Lefkowitz, M.J. Adams, E.B. Carstens. 9th Report of The International Committee for Taxonomy of Viruses (Elsevier Academic Press, San Diego, 2011), pp 1069–1089Google Scholar
- 17.H.W. Rossel, G. Thottappilly, Report of First Sweet Potato Planning Conference 1987, (International Potato Centre, Lima, 1988), pp 291–302 (1988)Google Scholar
- 40.J.J. Lo′pez-Moya, R.Y. Wang, T.P. Pirone, J. Gen. Virol. 80, 3281–3288 (1999)Google Scholar