Variation in the coat protein sequence of British isolates of Turnip yellow mosaic virus and comparison with previously published isolates

Arch Virol (2005) 150: 23472355

DOI 10.1007/s00705-005-0593-yE. J. Mitchell and J. M. BondCentre for Ecology and Hydrology Dorset, Winfrith Technology Centre,

Dorchester, U.K.Received January 7, 2005; accepted May 24, 2005

Published online August 1, 2005 c Springer-Verlag 2005Summary. Isolates of Turnip yellow mosaic virus (TYMV) were collected from

wild cabbage (Brassica oleracea) on a 400 m stretch of Dorset coastline.The coat protein genes of four isolates showed high homology in nucleotide

sequence (0.9701.000, mean 0.987). Lower levels of homology where found to

previously published sequences of Australian isolates [10] (0.7250.775, mean0.741).The amino acid composition of the Dorset isolates showed high levels of homology (0.9641.000, mean 0.986). Numerous amino acid substitutions occurred

between the Dorset and Australian isolates (0.7050.819, mean 0.742).Comparison with other isolates showed large genetic distances between the

Dorset isolates and both European and Australian isolates.Turnip yellow mosaic virus (TYMV) is a member of the genus Tymovirus which

infects a wide range of Brassica and non-Brassica hosts in northwest Eurasia

and Australia [8]. TYMV has isometric particles of approximately 30 nm in

diameter containing a 6.3 Kb single stranded RNA genome. The genome contains

three overlapping reading frames which encode a 206 K replicase protein, 69 K

movement protein and a 20 K coat protein [14].The coat protein of TYMV has been shown to play an important role in the

pathogenicity and virulence of TYMV by affecting the systemic movement of

the virus within its host [2]. Therefore variation in the coat protein gene and the

resulting changes in capsid protein composition between isolates may well be

indicators of differences in the pathology and ecology of individual isolates.Variation in the coat protein sequence of British isolates

of Turnip yellow mosaic virus and comparison

with previously published isolatesBrief Report2348 E. J. Mitchell and J. M. BondAlong the south coast of the UK there are extensive natural populations of

wild cabbage (Brassica oleracea) [19]. These consist of perennial plants which

can survive up to 20 years [13] allowing persistent infections of viruses to develop.

In one of these populations at Chapmans Pool, Dorset (SY956769), TYMV has

been present for a number of years, sometimes at high levels. For example, in

1997 62% of individuals were infected with TYMV [18]. By sequencing the coat

protein gene of...