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Figure 5: Phylogenetic tree of the family Potyviridae using amino acid sequence relationships of the coat protein. Inference based on the Fitch-Margoliash (1967) least squares method. The sequences were aligned using PILEUP (Devereux et al., 1984). Branch lengths are proportional to sequence distances. The dendrogram was bootstrapped 100 times (percent scores shown at nodes), and are not rooted. Many branches are condensed and may contain multiple viruses. BCMV+, for example, includes BCMNV, CABMV, DMV, PWV, SAPV, SMV, WMV and ZYMV, as well as all the viruses contained in the BCMV subgroup (AzMV, BlCMV, DeMV, and PStV). Similarly, the branch labeled BYMV+ included CYVV, PMV, PSbMV and PeMotV.

Viruses in the family Potyviridae are similar to members of the families Comoviridae, Picornaviridae, and Hypoviridae. Genomes of member viruses of these taxa are positive sense ssRNAs. Most have a VPg at their 5'-termini and a poly(A) tract at their 3'-termini. Their genomes are expressed initially as high molecular weight polyprotein precursors which are processed by viral-encoded proteases. Gene products involved in replication are conserved in gene order and gene sequence.

Bymo: siglum from barley yellow mosaic.

Ipomo: siglum from Ipomea and mosaic.

Maclura: siglum from host genus name "Maclura".

Poty: siglum from potato Y.

Rymo: siglum from ryegrass mosaic.

Tritimo: siglum from Triticum and mosaic.