The Identification, Cloning And Sequencing Of Isolates From Stripe And Necrosis Virus Of Processing Tomatoes In Xinjiang

Two isolates(PTV-1,PTV-2)were collected and isolated from naturally infected processing tomatoes with symptoms of yellow mosaic malformation and stripe necrosis. PTV-1 is a rod-shaped virus particles about 300nm×18nm. And the single-strand RNA is about 6.4kbp. The coat protein of this virus is approximately 17.6kDa. In the agar double-diffusion test between the virus and TMV antiserum, a clear band of precipitate was observed. A pair of primers were designed based on tobacco mosaic virus (TMV) RNA CP gene, and a fragment bout 700bp were amplified by RT–PCR. But there was nothing based on tomato masaic virus (ToMV) RNA gene. PTV-1 was identified as TMV.PTV-2 virus particles all have isometric virons with diameters ranging from 28-30nm. The coat protein of PTV-2 is approximately 27kDa. It contained three large single-strand RNAs of 3400bp,3100bp,2300bp,respectively. 1100bp is sub-gene belonging to RNA3. A clear band of precipitate was observed between the virus and CMV antiserum. A pair of primers were designed based on CMV RNA CP gene, and a fragment of about 776 bp was amplified by RT-PCR. The products of PCR were cloned into PUCm-T. The results showed that the cloned segment was 776 bp and contained one open reading frames(ORF), which was composed of 657 nucleotides encoding a polypetide of 218 amino acids. Comparison of the nucleotide and amino acid sequences of the full length of CP gene of PTV-2xinjiang with the corresponding sequences of several CMV I isolates showed that the homology are 90.9%-98.9% at nucleotide level, and 94.2%-98.6% at amino acid level. On the other hand, it were 76.4%-78.2% at nucleotide level, and 79.9%-83.5% at amino acid level with the strains of CMVⅡ, which suggested that the PTV-2xinjiang belongs to CMV I other than CMVⅡ.Through the researchs such as biology, serology and molecular biology etc, it is clear that PTV-1 xinjiang is TMV and PTV-2 is CMV. And PTV-2xinjiang belongs to CMV group I. It is confirmed that it was a basic reason of inducing processing tomatoes stripe and necrosis when two virus admixture infected.