| Cucurbits, including watermelon, cantaloupe, cucumber, and squash, are grown commercially throughout the world. These crops can be completely destroyed when infected by Zucchini yellow mosaic virus (ZYMV), Watermelon mosaic virus (WMV), and/or Cucumber mosaic virus(CMV). These viruses do not always kill the plant but often disrupt the natural processes so severely that the plant produces abnormal fruit or no fruit at all.One isolate, named as HF-WX, was isolated from infected watermelon leaves in Hefei suburbs. 9 plant species in 3 genera could be experimentally infected by this isolate. In Chenopodium amaranticolor, their dilution end-point (DEP) ranged from 10-4 to 10-5, thermal inactivation point (TIP) was between 60℃ and 65℃ and longevity in vitro was 20-23d at 20-22℃. The purified virus particles observed by electronic microscope were linear, about 750nm×13nm. The UV absorption spectrum was the typical one of nucleoprotein with A260/A280=0.84. The content of RNA is 5.5％。This isolate gave positive reactions with the antiserum against ZYMV and formed a completely fused precipitin line, but did not react with antisera against WMV-2, CMV, and SqMV. The aphids transiting results showed that different species of the aphids had different capacities in spreading HF-WX and the order of their influences was Myzus persicaes > Lipaphis erysimi > Aphis gussypii and Rhoposi phumpadi. Isolate HF-WX was propagated by the host plant cucurbits.(Zao Feng NO. 1) the purified virus particles of HF-WX inject hen and rabbit to prepare antiserum. the immunoglobulin IgY and IgG was purified from the yelk of egg and serum of rabbit, respectively. The titer of HF-WX antiserum and IgY is 1/1024 and 1/512 detected by miniprecipitation, respectively. Therefore this isolate produced biological symptoms similar to those caused by ZYMV in China. Biological properties of WMV-2 are similar to that of ZYMV, so we do some molecular analysis to confirm what isolate HF-WX is. we synthesized the upstream and downstream primers ZH1,ZH2 and ZH4,ZH5 according to the known WMV-2 and ZYMV coat protein gene sequence which had published in GenBank AB001994 and AF435425, respectively. The total RNA was extracted from cucurbits leaf infected with HF-WX, The first strand cDNA was synthesized from the total RNA template with synthetic 3′PCR primer using reverse transcriptase. A DNA fragment with 840bp was obtained after 35 PCR amplification circles with two specific primers mentioned above. After digested by XbaI and Bam HI the PCR fragment was inserted into the vector pGEM-3Zf(+) directionally. Transfer the recombinant DNA into competent E.Coli Jm109. Positive recombinant plasmid pGEM-3Zf(+)/ ZYMV-CP was extracted by alkaline lysis with SDS are screened by PCR amplification and digestion, followed by analysis on agarose gel. 3 positive clones was sequenced. The result of sequence showed that the 3 sequences were identical, which conclude that there was no mismatch base in PCR amplification and we got exact sequence. We submitted the sequence to GenBank and the accession number is AY597207. Analysis of nucleotides and deduced amino acid sequences provided that the sequence of the CP gene was 840 nucleotides, encoded 279 amino acids determined by sequence. Compared with the published sequences inland and abroad, it shared identities of 83%～97.3% in nucleotide sequences and 91.8%～99.8% in amino acid sequences and showed the most similarity with isolate Hainan (AF486823) of 97.3% and 99.8% in nucleotide sequence and amino acid sequence, respectively. The accession number of each sequences are as follows: AF435425,AF486822,AF486823,AF513551,AF513550,AF513552,AY074808,AY074809,AY074810,AJ429071,AJ459954,AJ459955,AJ459956,AB063251,D00692,D13914. Phylogenetic trees based on alignments of the ZYMV CP gene sequences mentioned above and generated by neighbor-joining method from DNAMAN software. Replicase,protease,VPg gene were divided into 3 fragments of S1,S2,S3 with the site of 1kb each. Synthesizing the primers acc...
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