A partial sequence of Oat mosaic virus (OMV) has been obtained for four iso
lates of the virus from four European countries. This represents the first
available sequence data for this important disease of winter-sown oats. The
longest clone of 1699 nucleotides was obtained from infected English oats
using a degenerate primer, designed to members of the Potyviridae family. A
lignment of the predicted amino acid sequence with members of the Potyvirid
ae showed closest identity with viruses of the Bymovirus genus. The predict
ed amino acid sequence has one open reading frame corresponding to part of
the NIb and capsid protein, with a 3' untranslated region of 351 nucleotide
s, followed by a poly(A) tail. PCR primers were designed to the coat protei
n and NIb gene of members of the Bymovirus genus and used to obtain partial
sequences of 1441 nucleotides at the 3' end of infected oats from both Wal
es and France. A specific primer set designed to the English isolate was us
ed to generate a product of 701 nucleotides from OMV-infected oat leaves fr
om Ireland. All four isolates are highly conserved at the amino acid level.