The Identification Of Processing Tomato Virus Types And Strain Identification Of XJB087 Isolate In Xinjiang

The virus disease of processing tomato was widely investigated in Kuitun, Shihezi, manasi, Changji, Yanqi and Bohu county in Xinjiang province during 2005 to 2006. The results showed that the virus disease incidence of processing tomato is from 73% to 91%, The average rate of diseased plants was 82.1%. The field symptoms of processing tomato virus disease have mosaic, leaf streak necrosis, fernbrake leaf and malformation, curl leaf and dwarf etc. various symptoms. but mainly were mosaic and leaf streak necrosis with infectious frequencies of 78%, 37%, and leaf streak necrosis symptom accompanies mosaic 90%. According to RT-PCR amplification the total RNA of virus infected processing tomatos what inoculated on the host and producted the special symptoms, Among the 221 tomato samples examined, RT-PCR identification results that TMV was the most common virus and infectious frequencies was 86.41%, and CMV was 28.1%, the infectious frequencies co-infected by TMV and CMV was 17.6%, PVY was 3.2%. Besides, Investigation show that the virus disease incidence of processing tomato is connected with to cultivating measures.A virus isolate XJB087 was obtained from infected processing tomato plants with mosaic symptoms in Bohu of Xinjiang Province, and was identified as one of PVY strain by symptoms on the test plants and doing RT-PCR amplification. The coat protein gene (CP) was amplified from the extracted plant total RNA by using RT-PCR, and cloned into the pMD20-T vector and sequenced. The cloned segment is 801 bps and encodes 267 amino acid residues and shares 98.1%, 97.1%, 89.8%, 89.9% identity of nucleotides and 98.9%, 97.3%, 92.5%, 92.1% identity of amino acids with that of PVYN strain, PVYO strain, PVYMN strain and PVYNTN strain. The distances of XJB087 CP gene of all strains analyzed by phylogene -tic tree, it can conclude that XJB087 is nearest to PVYN strain. Primers were designed according to the sequence of HC-Pro gene of PVY, using RT-PCR to amplify the HC-Pro gene from the extracted plant total RNA, and a specific fragment of 1368 bps corresponding in size to the PVY HC-Pro gene was amplified. The products of PCR were cloned and sequenced. It was analyzed by the phylogenetic tree,that XJB087 shares the hightest homology of 94% with PNYN strain and 92% putative amino acid sequences, thus it was identified as an isolate of PVYN.