Nucleotide sequences of the coat protein genes of two aphid-transmissible strains of soybean mosaic virus.

The nucleotide sequences of the coat protein genes and 3' non-coding regions of two aphid-transmissible isolates (G2 and G7) of soybean mosaic virus (SMV) were determined. The coat protein of the G2 isolate differs from that of the aphid non-transmissible N isolate by a single amino acid at position 12 (aspartic acid in N, glycine in G2 and G7). The G7 isolate differs from G2 and N at three and four amino acid residues, respectively. The nucleotide sequence similarity of the three isolates in the coat protein coding and 3' non-coding regions ranges from 93 to 100%, respectively. In contrast, watermelon mosaic virus 2 (WMV 2) is only 77% to 79% similar to the SMV isolates, suggesting that WMV 2 is a distinct virus and not an isolate of SMV as proposed previously.