Study Of Variation Of Potato Virus Y Strains In Tobacco In Major Tobacco Areas In China

Tobacco leaves samples were collected which showed typical PVY symptoms. 51 PVY samples were dected as positive with Double Antibody Sandwich enzyme-linked immunosorbent assay(DAS-ELISA) method. After inoculated onto Lycium barbarum L.which is necrotic lesion host of PVY, PVY was purified and maintained on Nicotiana tabacum SamSun NN plant, we got 51 PVY isolates. The CP gene was cloned and sequenced. Based on the difference of 51 PVY CP genes, four PVY isolates were selected to amplify the complete sequence, 15 PVY isolates were selected to inoculate on 7 spieces of hosts. According to affinity and homology of 51 PVY isolates based on difference of 51 PVY CP genes, 51 PVY isolates can be divided into two subgroups. Based on difference of CP genes, according to affinity and homology of 51 PVY isolates with PVY strains registered NCBI (http://www.ncbi.nlm.nih.gov/), PVY isolates were classifed as four strains(PVYO, PVYN, PVYN:O, PVYNTN) refering to the criterion Shukla and Ward posed to divided Potyirus. After sequencing of PVY isloates(HC-2, YS-11, Guiding-3, WA-13), the complete sequences of four PVY isolates and PVY strains registered NCBI (http://www.ncbi.nlm.nih.gov/)were blasted with DNAMAN and MEGA software, then Phylogenetic trees were made, four PVY isolates(HC-2, YS-11, Guiding-3, WA-13) were classified as PVYNTN, PVYN, PVYN, PVYO. According to difference of symptoms of 7 hosts, PVY was divided into subgroups:PVYNstrain and PVYO strain. The methods of dividing PVY on molecular level, the reason and applicition of PVY geographic differences, population genetic structure was discussed in the article and we got conclutions as follows:1. 51 PVY CP genes were cloned and sequenced. PVY CP gene contains 801 bases and encodes coat protein including 267 amino acids.2 PVY CP gene was divided into two regions: High mutation frequency region and low frequency region based on analysis of PVY CP gene and coat protein.3. According to the difference of PVY CP gene and coat protein., 51 PVY isolates were divided into two subgroups, named PVYO/N:O, PVYN/NTN.4. The complete sequences of four PVY isolates were obtained which contain 9699 bases and only one ORF composed of 9186 bases encoding a polyprotein including 3061 amino acids.5. PVY in major tobacco areas in China can be classified as PVYNTN, PVYN, PVYO. PVYN is the dominant one.