Watermelon bud necrosis tospovirus is a distinct virus species belonging to serogroup IV

The nucleocapsid protein gene of a tospovirus infecting watermelon in India was cloned and sequenced. Sequence analyses showed that the gene was most closely related to those of watermelon silver mottle tospovirus (WSMV) from Taiwan and peanut bud necrosis tospovirus (PBNV) from India, the two definitive species of serogroup IV. Amino acid sequence similarity was 84% and 82% with WSMV and PBNV. respectively. On the basis of the sequence divergence and the previously determined host range differences, the watermelon tospovirus, designated as watermelon bud necrosis tospovirus, should be considered as a distinct species belonging to serogroup IV.