Molecular Identification of Strains of Potato virus Y Derived from Infected Tobacco Plants in Qiannan

To reveal the rules of distribution and molecular variation of strains of Potato virus Y(PVY) in Qiannan tobacco belt of Guizhou,PVY strains were initially identified by serological method;further,19 selected PVY isolates were subjected to molecular identification.The results showed that all the cloned fragments of the 19 PVY cDNA were 1074 nts in full-length,containing a complete cp gene of 801 nts and encoding 266 amino acids.The results of sequence comparison showed that the similarity of nucleotide sequence of cp genes in the 19 PVY isolates was 87.0%-99.9%,and the similarity with the cp genes in the 17 PVY strains logged in GenBank was 86.6%-99.9%.Phylogenetic tree analysis indicated that 3 of the 19 PVY isolates from Qiannan had closer relationship with PVYN and PVYNTN,and the other 16 PVY isolates were more closely related to PVYN∶O.