两种桑树病毒的形态观察与检测

桑树病毒病一直是影响蚕桑产业发展的重要因素之一, 但其病原也尚未完全确认。本研究收集全国不同桑园、不同时间和不同品种的皱缩状和花叶状桑叶样品, 分离病毒后使用透射电子显微镜观察病毒形态特征。结果在桑病叶中分离获得两种病毒, 一种为双联体形态病毒, 长(27.84±1.71)nm, 宽(17.05±1.13)nm, 形态特征与双生病毒属的病毒形态特征一致; 另一种为球状体病毒(80~100 nm), 形态特征与番茄斑萎病毒属的病毒形态特征一致; 桑叶切片观察, 发现同一桑叶材料中存在这两种病毒。通过高通量测序发现其存在桑花叶型萎缩病相关病毒Mulberry mosaic dwarf associated virus (MMDaV)和桑脉带相关病毒Mulberry vein banding associated virus (MVBaV)。设计上述病毒的特异引物, 对158份桑病叶进行PCR检测, MMDaV的检出率为93.04%; 而MVBaV为60.13%, 同时检出率为57.59%。结果表明, MMDaV和MVBaV在桑病叶中普遍存在, 且同时存在。本研究首次在桑树病叶中同时观察并检测到MMDaV和MVBaV, 二者在桑皱缩状和花叶状的桑叶中存在混合感染的现象, 研究结果将为今后深入研究桑病毒病及防控奠定了基础。

Morphological observation and detection of two mulberry virus

Mulberry viral disease is one of the most important factors affecting the development of sericultural industry, but the pathogens of mulberry viral disease have been long unclear. In this study, two viruses were isolated from the diseased mulberry leaf samples with crinkle or mosaic leaf symptoms collected from different varieties and different sericultural regions in China at different time and further examined by transmission electron microscope. One virus showed similar morphological features to geminivirus, and the length of virus particles was (27.84±1.71)nm and width was (17.05±1.13)nm. Another was a globular virus with the length between 80 and 100 nm and showed similar morphological features to Tospovirus. Both virus particles were observed in one mulberry leaf, and Mulberry mosaic dwarf associated virus (MMDaV) and Mulberry vein banding associated virus (MVBaV) were detected through high-throughput sequencing. Furthermore, 158 diseased mulberry leaf samples of mulberry leaf were detected by specific identification PCR.The detection rates of MMDaV and MVBaV were 93.04% and 60.13%, respectively, and the detection rate of both was 57.59%. This was the first report that MMDaV and MVBaV were detected to coexist in the diseased mulberry leaf, which will provide a foundation for future study of mulberry viral diseases.