Molecular characterization and comparison of tomato zonate spot virus isolated in Japan and China

The complete genome sequence of Orthotospovirus tomatozonae (tomato zonate spot virus, TZSV) isolated in Japan was determined and compared with that of Chinese isolates. The lengths of the S, M, and L segments of the RNA genomes of the Japanese isolate (TZSV-TZ1-3) were 3194, 4675, and 8916 nucleotides, respectively, which were similar to the Chinese isolates. Moreover, the eight motifs on the RNA-dependent RNA polymerase (RdRp) gene were conserved in both TZSV-TZ1-3 and Chinese TZSV isolates (TZSV-Bidens and TZSV-Tomato-YN). The nucleotide identity of the genes among the TZSV isolates was more than 94%, indicating low diversity among viruses. The phylogenetic analysis and the prediction of the cleavage sites in the glycoprotein showed that the TZSV-TZ1-3 isolate was closely related to TZSV-Tomato-YN isolated from China. However, there were unique frameshifts and deletions on the RdRp and glycoprotein genes of the TZSV-Tomato-YN isolate, suggesting that both isolates were genetically distinct. The findings of this study indicate that the TZSV-TZ1-3 isolate originated in China and show the sequence diversity among TZSV isolates.