| Budget Amount *help |
¥3,800,000 (Direct Cost: ¥3,800,000)
Fiscal Year 2004: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 2003: ¥2,600,000 (Direct Cost: ¥2,600,000)
|
|---|
| Research Abstract |
The genomes of a representative worldwide collection of thirty-two Turnip mosaic virus(TuMV) isolates were sequenced and these, together with six previously reported, were analysed. At least one fifth of the sequences were recombinant. In phylogenetic analyses, using genomic sequences of Japanese yam mosaic virus as an outgroup, the TuMV sequences that did not show clear recombination formed a monophyletic group with four well-supported lineages. These groupings correlated with differences in pathogenicity and provenance ; the sister group to all others was of Eurasian B-strain isolates from non-brassicas, and probably represents the ancestral TuMV population, and the most recently ‘emerged' branch of the population was probably that of BR-strain isolates found only in east Asia. Eight isolates, all from east Asia, were clear recombinants, probably the progeny of recent recombination events, whereas a similar number, from other parts of the world, were seemingly older recombinants. Thi
… More
s difference indicates that the presence of clear recombinants in a sub-population may be a molecular signature of a recent ‘emergence'.
The genetic structure of populations of Turnip mosaic virus in Eurasia was assessed by making host range and gene sequence comparisons of 142 isolates. Most isolates collected in west Eurasia infected Brassica plants whereas those from east Eurasia infected both Brassica and Raphanus plants. Analyses of recombination sites(RSs) in four regions of the genome (one third of the full sequence), showed that the P1 gene had recombined more frequently than the other gene regions in both sub-populations, but that the RSs were located in different parts of the genomes of the sub-populations. Estimates of nucleotide diversity showed that the west Eurasian sub-population was more diverse than the east Eurasian sub-population. These sub-populations seem to have evolved independently from the ancestral European population, and their genetic structure probably reflects founder effects. Less
|
