[Sequence analysis of the coat protein gene of Chinese soybean mosaic virus strain SC7 and comparison with those of SMV strains from the USA].

To unveil genetic variations between the predominant soybean mosaic virus (SMV) strains in China and in the USA, as well as to reveal the potential relevance between the similarity of gene sequences and the virulence of the viruses, we isolated and sequenced the coat protein (CP) gene of Chinese SMV strain SC7 by RT-PCR and compared the SC7 sequence with those of SMV strains from the USA. Analysis is showed that the CP gene of SC7 was 795 nucleotides in length and encoded 265 in amino acids'. The CP gene of SC7 and those of the strains from the USA exhibited 4%-5% nucleotide diversity and 1%-2% diversity amino acids. The conserved amino-acid sequence associated with aphid spread in the USA strains was DAG, and corresponded to DAD in SC7. The virulence of SC7 was greater than that of the SMV strains from the USA. Nevertheless, no clear relationships between sequence similarity of the CP genes from different strains and their virulence on differential hosts were found.