Molecular Identification Of The Potyviruses And Study On Their Inherited Differentiation In Cucurbit Crops In North Xinjiang

Cucurbit corps is one of the important economic crops in Xinjiang. In recent years, The Cucurbit crop production in Xinjiang has been directly hurted by the spread of the virus diseases. The diseases became more and more serious, and was extensively spreaded with introduction and change of variety. The virus diseases cause serious damage to the output and quality of melons. The thesis is preliminary identification and research for kinds of Potyviruses on Cucurbit crops in northern Xinjiang.In recent years, the Cucurbit Potyvirus virus has been reported in China, such as watermelon mosaic virus 2 (WMV-2), Zucchini yellow mosaic virus (ZYMV) and papaya ringspot virus strain watermelon (PRSV-W) (the original WMV-1 was proved that is a strain of PRSV-W) against the most serious.A variety of Cucurbits samples was collected from Changji, Shihezi, and other places in north Xinjiang, The coat protein gene of Zucchini yellow mosaic virus (ZYMV) and watermelon mosaic virus 2 (WMV-2)was amplified via RT-PCR from total RNA of infectd Cucurbit leaves and cloned pMD18-T vector. Sequence analysis indicated that the nucleotide fragment contains 1185bp and includes complete CP gene obtained from infecting Cucumis sativus, Cucumis melo, and Luffa cylindrical leaves in shihezi.The obtained sequences were compared with other 7 reported ZYMV which were isolated from different regions of the world and host plant. The fragment includes 837 nucleotides of the CP that encodes 279 amino acids, and 135 regional nuclear NIb glycosides acid encoding 45 amino acids. The alignment at home and abroad have reported seven ZYMV sequence, its nucleotide homology of up to 94.44%, amino acid sequence homology of up to 97.48%, resulting from the the molecular level to prove that the virus Zucchini yellow mosaic virus; Nucleic acid sequence of CP gene was found relating to their host origin but little difference with geological distribution. Similar results were obtained from the CP amino acid sequences deduced from nucleic acid sequences.Watermelon mosaic virus-2 (WMV-2)was detected in infected pumpkin plant collected from Changji of Xinjiang by RT-PCR. The sequence analysis showed that: the nucleotide fragment contains 917bp and includes complete CP gene.When obtained sequence data was compared with previously reported sequences of 12 WMV-2 isolates from different regions,the data shared identities of 93.6%～97.5% in nucleotide acids and 94.9%～98.9% in amino acid respectively. The Xinjiang isolate has two amino acids in N′of coat protein, similary as isolates from Zhengzhou and Japan.but the different nucleotide acids and amino acid. The Xinjiang isolate has two amino acid residues to be obviously different from all other isolates, particularly the motif sequence associated with aphid transmission ware changed from DAG into DAE.