The complete nucleotide sequence of barley mild mosaic virus RNA1 and its relationship with other members of the Potyviridae.

The complete nucleotide sequence of RNA1 of a French barley mild mosaic bymovirus isolate has been determined. The molecule is composed of 7261 nucleotides and contains a single large open reading frame encoding a protein of 2258 amino acids with a calculated Mr of 256,375. Amino acid sequence comparison with poty- and rymoviruses reveals eight domains corresponding to the potyviral P3, 6K1, Cl, 6K2, Nla-VPg, Nla-Pro, Nlb and capsid proteins, respectively. Seven putative cleavage sites, similar to those mediated by potyvirus Nla proteinases, were identified. The presence of two, so far undescribed putative cleavage sites (6K2/Nla-VPg and Nla-VPg/Nla-Pro) in the polyproteins encoded by RNA1 of barley yellow mosaic virus and wheat spindle streak mosaic virus, was predicted. These data indicate that the bymovirus RNA1 fits the consensus potyviral genetic map downstream of the helper component gene.