Arch Virol (2002) 147: 683–693
Characterisation of a potyvirus and a potexvirus
from Chinese scallion
, H. Y. Zheng
, J. P. Chen
, and M. J. Adams
Department of Biotechnology, College of Life Sciences,
ZhejiangUniversity, Hangzhou, People’s Republic of China
Virology Department, Zhejiang Academy of Agricultural Sciences,
Hangzhou, People’s Republic of China
Department of Plant Protection, HuazhongAgricultural University,
Wuhan, People’s Republic of China
Plant Pathogen Interactions Division, IACR-Rothamsted, Harpenden, U.K.
Accepted December 20, 2001
Summary. Molecular analyses of viruses infectingChinese scallion (Allium
chinense G. Don) showed that the plants did not contain any of the poty-, carla- or
allexiviruses that are common in garlic plants in China.Thecompletesequences of
a potyvirus and a potexvirus were determined and these were shown to represent
different viruses from any in the databases. They could be transmitted mechani-
cally to scallion but not to other Allium species (includinggarlic) or to Narcissus.
The potyvirus, tentatively named Scallion mosaic virus, has a distant relationship
(c. 62% nucleotide identity over the entire genome) to Turnip mosaic virus and
Japanese yam mosaic virus, with which it grouped in phylogenetic analyses. Its
genome is 9324 nts long, encoding a 341.3 kDa polyprotein of 3001 amino acids.
The potexvirus, tentatively named Scallion virus X, has a genome 6987 nts long
and its organisation was similar to that of the other potexviruses but with only
46.3–63.2% nucleotides identical to them. It is most closely related to Narcissus
mosaic virus but phylogenetic analyses indicate that it should be considered a
distinct species. Neither of the viruses have been detected in garlic, although the
two host plants are closely related.
Virus diseases are a particular problem in vegetatively propagated plants amongst
which are a number of bulb crops, particularly Allium species (onion, garlic etc.).
We have recently used degenerate primers to detect and then to sequence virus
isolates from garlic plants with mosaic symptoms growing in China and showed