Arch Virol (1999) 144: 231–240
Complete nucleotide sequence of the genomic RNA of a Japanese
yam mosaic virus, a new potyvirus in Japan
S. Fuji and H. Nakamae
Aichi-ken Agricultural Research Center, Nagakute, Aichi, Japan
Accepted September 14, 1998
Summary. We determined the complete nucleotide sequence of a potyvirus
puriﬁed from a Japanese yam plant. The genomic RNA of this virus is 9 757
nucleotides (nts) in length, excluding the 3
-terminal poly(A) tail. It contains a
single open reading frame (ORF) encoding a polyprotein of 3130 amino acids
(aa) with a calculated Mr of 356,793. The genomic organization of this potyvirus
is similar to that of other members of the genus Potyvirus and nine potential
cleavage sites for the viral proteinase were found by comparison of its sequence
with those available for other potyviruses. The nucleotide sequence and genome
characteristics show that this isolate is a new potyvirus species. Its polyprotein
differs substantially from Yam mosaic virus (YMV) (50% amino acid sequence
identity) and fourteen other potyvirus species examined (44–59% identity).
Although this potyvirus has been classiﬁed as YMV, our results suggest that
the potyvirus infectious to the Japanese yam plant in Japan is distinct from YMV.
Therefore, we propose that the Japanese yam potyvirus should be designated as
Japanese yam mosaic virus (JYMV).
Yams, including the Japanese yam (Dioscorea japonica) and Chinese yam
(Dioscorea opositta), are grown widely in Japan as a vegetable. A virus infecting
yam plants in Japan was ﬁrst isolated in 1974 . Infected plants show mosaic
and green-banding of leaves and a signiﬁcantly reduced yield. The symptoms of
this virus are very similar to those caused by the yam mosaic virus (YMV).
Reduction of the yam crop by YMV infection is economically damaging in
Africa, North America, South America, and Asia. YMV is a member of the genus
Sequence data from this article has been deposited with the DDBJ/EMBL/GenBank
database under accession number AB016500.