西瓜花叶病毒和小西葫芦黄花叶病毒复合侵染南瓜的透射电镜诊断

Electron microscopic diagnosis of multiple pathogen of Watermelon mosaic virus and Zucchini yellow mosaic virus in infected Cucurbita moschata

应用透射电镜和RT？PCR技术对浙江龙游的南瓜黄化花叶病株进行病原诊断，电镜负染色观察到病株汁液中存在大量线状病毒粒子，超薄切片观察到病叶细胞质中存在III型、Ⅳ型两种类型的风轮状内含体，细胞质中膜结构增生形成许多小泡结构，叶绿体产生周边空泡。用西瓜花叶病毒（ WMV）和小西葫芦黄花叶病毒（ ZYMV）特异性引物扩增到622 bp和696 bp目的片段，序列测定发现与WMV和ZYMV 同源性分别为88％～95％、93％～99％。根据以上结果诊断南瓜病株为WMV和ZYMV复合侵染。

The multiple infecting pathogens were detected in a sample of yellow mosaic Cucurbita moschata from Longyou, Zhejiang province, by electron microscopy and RT-PCR. Filamentous virus particles of 600 ~800 nm in length were observed in Cucurbita moschata by negative staining. The pathological study revealed that III-type andⅣ？type cylindrical inclusions appeared in cytoplasm of the infected cells. Chloroplast vacuolization and membranous proliferation were also found in the infected cells. There were 622bp and 696bp special productions in gel electrophoresis after RT-PCR using universal primers of WMV and ZYMV,respectively. Sequencing after RT-PCR revealed that the 622bp and 696bp special productions had homology of 88% ~95% with the WMV sequence and 93%~99% with the ZYMV sequence, respectively. The results above suggested that Cucurbita moschata were multiple-infected by WMV and ZYMV.