Biological and molecular characterization of Soybean yellow common mosaic virus, a new species in the genus Sobemovirus.

A novel soybean-infecting sobemovirus termed Soybean yellow common mosaic virus (SYCMV) was characterized. The virus has a single, positive-strand RNA genome of 4152 nucleotides. The virus contains four putative open reading frames encoding P1 (78-566 nt), polyprotein ORF2a (524-2248 nt), polymerase domain ORF2b (1852-3417 nt), and CP (3227-4030 nt). The entire nucleotide sequence of SYCMV showed 31.2-71.3% nucleotide identity with the previously known eleven species of sobemovirus. In host range analysis of SYCMV, in which twenty one species and three different Nicotiana tabacum cultivars belonging to seven families were inoculated with the virus, SYCMV had a narrow host range, infecting only Glycine max and G. soja. Based on the obtained sequence, full-length clones of SYCMV were constructed. Symptoms produced by inoculation with clones were indistinguishable from those produced by inoculation with sap from symptomatic plants. Viral RNA accumulation of SYCMV was detected in the upper leaves by Northern blotting. This indicated that full-length clones of SYCMV were sufficient to produce disease symptoms. Genomic organization, the predicted amino acid sequence, and phylogenetic analyses with known sobemoviruses confirmed the assignment of SYCMV as a new member of the genus Sobemovirus.