Virulence differentiation of bean common mosaic potyvirus in leguminosae crops

Forty six isolates of bean common mosaic virus (BCMV) collected from azuki bean, mungbean, kidney bean, cowpea, broad bean and peanut were classified into three groups based on biological, serological, cytopathological, and molecular characteristics. Group I induced vein-banding symptoms in cowpea which was similar to those produced by the BCMV-cowpea strain. Group II caused mosaic symptoms in azuki bean but not in peanut and tobacco. Since this character was different from that of previously described BCMV strain, group II may not belong to BCMV GroupIII induced vein-clearing symptoms in azuki bean, kidney bean and peanut, which are typical symptoms for BCMV-peanut stripe virus strain. Virus inclusion patterns of BCMV groups were similar to those of Potyvirus subdivision III with the scroll, pinwheel and long laminated inclusions. However, the inclusions of laminated aggregates were never observed in mungbean isolates. Multiple alignment as well as cluster dendrograms of 3'noncoding region (3'-NCR) and a part of coat protein gene (CP) suggested that group I belongs to the BCMV-cowpea strain, group II to the BCMV-azuki bean strain, and group III to the BCMV-peanut stripe virus strain. Since molecular phylogenesis of BCMV based on nucleotides of 3'-NCR and coat protein differed from the grouping based on virulence differentiation, and BCMV groups are more closely related to each other with the same host origin, other characteristics of those strains are under investigation.