| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2000: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 1999: ¥2,400,000 (Direct Cost: ¥2,400,000)
|
|---|
| Research Abstract |
Turnip mosaic virus (TuMV), a species of the genus Potyvirus, occurs worldwide. Seventy six isolates of TuMV were collected from around the world, mostly from Brassica and Raphanus crops, but also several non-brassicaceous species. Host tests grouped the isolates into one or other of two pathotypes. The nt sequences of the first protein (P1) and coat protein (CP) genes of their genomes were determined. The phylogenetic relationships of these sequences were assessed separately. The taxonomies of the two genes were similar, and revealed two broadly consistent host-specific lineages among the isolates, and also clear geographic clustering ; one lineage was mostly from Raphanus crops in East Asia, the other was genetically and geographically much more diverse and came from Brassica crops and non-brassicaeous species. Further comparisons showed that many of the isolates were recombinants, some multiply and most intragenically. They also showed that the most consistent phylogenetic signal delimiting the Raphanus lineage came from the 3' terminal half of the P1 gene and the 5' terminal half of the CP gene. The phylogenetic relationships indicate that genomic recombination and host adaptation have occurred during migratory spread of the virus, perhaps from the Mediterranean region and Europe to the other parts of the world, and that the Raphanus pathotype lineage has recently evolved in East Asia. This is probably the most detailed study yet on the origins, worldwide migratory spread, host adaptation, pathogenic segregation and genetic recombination of a single plant virus species currently causing a world crop pandemic. Moreover, molecular evolution of Potato virus Y necrotic strain in Japan was investigated.
|
