Analysis of the tomato mild mottle virus genome indicates that it is the most divergent member of the genus Ipomovirus (family Potyviridae)

The complete genome of a tomato mild mottle virus (ToMMV) isolate was analysed, and some biological features were characterized. The ssRNA genome of ToMMV from Ethiopia encompasses 9283 nucleotides (excluding the 3' poly(A) tail) and encodes a polyprotein of 3011 amino acids. Phylogenetic and pairwise comparisons with other members of the family Potyviridae revealed that ToMMV is the most divergent member of the genus Ipomovirus, with a genome organization similar to that of members of the species Sweet potato mild mottle virus, the type species of the genus. In contrast to earlier reports, ToMMV isolates from Yemen and Ethiopia were not transmitted by the aphid Myzus persicae, but they were transmitted very erratically by the whitefly Bemisia tabaci. A comparison of the 3'-proximal sequences of different isolates provided evidence for geographically associated genetic variation.