Molecular variation characterization of the genome 5' terminal region of PVY isolated from tobacco in China
Tobacco viral diseases, of which most are RNA viruses, are a category of infectious diseases that are distributed widely and occur severely. The natural variation (mutation) of tobacco viruses proceed quickly, and cause considerable difficulty for prediction and prevention. In order to clarify molecular variation characterization and strain separation of PVY isolated from tobacco, RT-PCR was used to amplify the 5' end of the genome of 3 PVY isolates coming from tobacco-growing areas in Shannxi and Guizhou Provinces of China, and the nucleotide sequence was analysed. The PCR fragment is about 1730nt, and located in the 5' end of the PVY genome. The sequence included complete 5' UTR and P1 gene, and partial HC-Pro gene. Shannxi 2 showed low nucleotide identity and amino acid similarity with Guizhou 1 and Guizhou 6. The major variable region was located in 3' end of 5' UTR and 5' end of P1 gene. PVY had high genetic variability compared Shannxi 2, Guizhou 1 and Guizhou 6 with 32 PVY isolates. Phylogenetic tree analysis of the 5' terminal nucleotide sequence and P1 amino acid sequence of PVY revealed the existence of three distinct groups.