Relationships among bean common mosaic virus, blackeye cowpea mosaic virus, azuki bean mosaic virus, and soybean mosaic virus.

Abstract

The host range, transmission, cross-protection, antigenic relationships, and coat proteins of four distinct potyviruses (bean common mosaic virus (BCMV), blackeye cowpea mosaic virus (BlCMV), azuki bean mosaic virus (AzMV), and soybean mosaic virus (SMV)) were compared. BCMV, BlCMV, AzMV and SMV were easily distinguished by the host range and seed transmission. Two BCMV isolates, two BlCMV isolates and AzMV were serologically identical according to examination by agar gel diffusion plates containing 0.5% lithium 3, 5-diiodosalicylate. Five SMV isolates from Japan were serologically identical and distantly related to a SMV isolate from Thailand. BCMV, BlCMV and AzMV were distantly related to SMV. None of these viruses were serologically related to turnip mosaic virus (TuMV). Positive cross-protection was found between BCMV and BlCMV, between BCMV and AzMV, and between BlCMV and AzMV. The molecular weights of the coat proteins of the virus isolates estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, were 32.8×103(K) for two BCMV isolates, two BlCMV isolates and AzMV, 30.1K for five SMV isolates from Japan, 31.5K for a SMV isolate from Thailand, and 34K for TuMV. The patterns of the peptides of two BCMV isolates, two BlCMV isolates and AzMV after cleavage with Staphylococcus V8 protease appeared nearly identical. Likewise, polypeptide patterns of five SMV isolates from Japan were also very similar. Good correlation was found among serological typing, molecular weights, and peptide mapping data of 12 virus isolate proteins. These findings suggest that SMV is a distinct virus, while BCMV, BlCMV and AzMV are virus strains, not distinct viruses.