Submitted to: Virology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/14/2000
Publication Date: 5/10/2000
Citation: Shirako, Y., Suzuki, N., French, R.C. 2000. Similarity and divergence among viruses in the genus furovirus. Virology.270:201-207. Interpretive Summary: The type species of the plant virus genus Furovirus is soilborne wheat mosaic virus, an important viral pathogen of wheat worldwide. The main characteristics of viruses in this genus are transmission by a soilborne fungus and rod-shaped virus particles. In this study we report the genome sequences of a Japanese strain of soilborne wheat mosaic virus and a new Furovirus, sorghum chlorotic spot virus, from Kansas. These sequences were compared with sequences of other soilborne viruses of wheat and oats from the U.S., Europe, and China. Our analysis indicates that sorghum chlorotic spot virus is a distinct virus species that diverged before the other viruses. There is also evidence that in the past there has been genetic exchanges among the wheat and oat viruses from Japan, China, Europe, and the U.S. Notably, all of the soilborne viruses of wheat from all geographic regions have identical biological and pathological properties. We therefore epropose that all of these wheat viruses be considered to be strains of soilborne wheat mosaic virus, rather than being named as distinct virus species.
Technical Abstract: Nucleotide sequences of RNAs 1 and 2 of a Japanese strain of soil-borne wheat mosaic virus (SBWMV), the type species of the genus Furovirus, and sorghum chlorotic spot virus (SCSV) were determined from cloned cDNA. The genomic relationship among six furoviruses including the Japanese and US strains of SBWMV, Chinese wheat mosaic virus (CWMV), European wheat mosaic virus (EWMV), oat golden stripe virus (OGSV) and SCSV, were examined. The Japanese strain of SBWMV and SCSV had the same genome organization as the other four previously sequenced furoviruses. The Japanese strain of SBWMV was most closely related to OGSV in RNA 1 with 87% amino acid sequence identity in the RNA polymerase domain and to EWMV in RNA 2 with 92% amino acid sequence identity in the capsid protein. SCSV was most distantly related to the other five furoviruses. Among the six furoviruses, RNA1 sequences of the US strain of SBWMV and CWMV were the most closely related, ,whereas RNA2 sequences of the Japanese strain of SBWMV and EWMV were most closely related. Phylogenetic analysis also indicated that there may have been an ancient reassortment between RNAs 1 and 2 of the five graminae- infecting furoviruses, while SCSV was shown to have separated from the rest before the other five furoviruses diverged. The fact that CWMV and EWMV have almost identical biological properties to the two strains of SBWMV suggests that they be regarded as strains of SBWMV. OGSV and SCSV are distinct both in biological properties and in nucleotide sequence and should be considered distinct species in the genus Furovirus.