侵染南瓜的西瓜花叶病毒和黄瓜花叶病毒CP基因的克隆和序列分析

采用RT-PCR的方法，用马铃薯Y病毒属病毒3′-末端序列的简并引物和黄瓜花叶病毒（Cucumber mosaic virus, CMV）外壳蛋白（CP）基因的特异引物，对采自山东聊城的一表现花叶、黄化、蕨叶及果实畸形的南瓜样品进行了检测，同时扩增到了西瓜花叶病毒（Watermelon mosaic virus, WMV）和CMV 2种病毒的基因组片段，说明该样品受到WMV和CMV 2种病毒的复合侵染。这2个病毒分离物分别被命名为WMV-liaocheng和CMV-liaocheng。序列测定及分析结果表明，它们与其它相应病毒分离物CP基因核苷酸序列的同源性分别为91.2-98.0%和77.0-97.9%，推导的氨基酸序列同源性分别为96.4-98.5%和81.2-99.1%。根据完整CP 基因核苷酸序列构建的系统进化树显示：18个WMV分离物可分为3组，其中WMV-liaocheng 与HLJ、CHN及Habenaria等分离物表现出较近的亲缘关系，形成Ⅲ组；30个CMV分为两个亚组，其中CMV-liaocheng属于亚组I，CMV-liaocheng可能发生过重组。

Cloning and sequence analyses of the coat protein genes of Watermelon mosaic virus and Cucumber mosaic virus from one mix-infected squash plant

Watermelon mosaic virus（WMV） and Cucumber mosaic virus（CMV） were detected from one mix-infected pumpkin（Cucurbita moschata） plants in Liaocheng,Shandong Province.The nucleotide sequences of coat protein（CP） gene and the 3 ＇-untranslated regions（3＇-UTR） of WMV（WMV-liaocheng） and CP gene of CMV（CMV-liaocheng） were determined from RT-PCR derived cDNA clones.Compared with sequences of corresponding viruses that are available in the GenBank,the CP genes of WMV-liaocheng and CMV-liaocheng shared similarity of 91.2%-98.0%,77.0%-97.9% at nucleotide level,and identity of 96.4%-98.5%,81.2%-99.1% at amino acid level,respectively.The phylogenetic trees constructed with the complete nucleotide sequence of the CP genes showed that 18 WMV isolates were clustered into 3 groups and WMV-liaocheng belonged to group Ⅲ;30 CMV isolates were divided into 2 subgroups,and CMV-liaocheng,Fny,Ixora,O,Y and NT9 were in subgroup I（CMV-I）.There were probably recombination event during the evolution of CMV-liaocheng.