甘薯羽状斑驳病毒和甘薯褪绿矮化病毒复合侵染甘薯引起的细胞病理学研究

Cyto-pathology study of sweet potato induced by synergetic infection of Sweet potato feathery mottle virus and Sweet potato chlorotic stunt virus

2011～2012年在浙江杭州连续发现感病甘薯植株具有甘薯病毒病SPVD的典型症状,透射电镜观察发现其叶片包含有长度为600～900 nm,直径为12 nm的线状病毒粒子。使用特异性引物进行RT-PCR扩增及测序,其病原为甘薯羽状斑驳病毒(Sweet potato feathery mottle virus,SPFMV)和甘薯褪绿矮化病毒(Sweet potato chlorotic stunt virus,SPCSV)复合侵染。运用透射电镜研究SPVD引起的细胞病理学变化,观察到叶肉细胞的细胞质中含有马铃薯Y病毒属特征性柱状内含体,其结构分类为Ⅳ型;线状病毒样粒子以束状平行排列成聚集体的方式存在于细胞质中;叶绿体伸出伪足状结构包裹线粒体。在维管束细胞的筛管和伴胞中观察到弯曲线状病毒样粒子形成的聚集体,其粒子排列交错,与叶肉细胞中平行排列的病毒样粒子聚集体不同,符合毛形病毒属特征。另外还在维管束和叶肉细胞结合的部位发现复合侵染的细胞病理学特征。本研究表明危害甘薯生产的SPVD已扩散蔓延到浙江省。

In 2011 and 2012, cultivars of sweet potato with the likely syptom of sweet potato virus disease （SPVD） were found in Zhejiang, Hangzhou. The infected leaf was taken under transmission electron microscopy （TEM） for pathogen observation. Linear virus particles with the length of 600 -900 nm, diamater of 12 nm was observed. For further molecular pathogen identification, specific primers were used to carry out RT-PCR and sequencing. At last, Sweet potato feathery mottle virus （SPFMV） and Sweet potato chlorotic stunt virus （SPCSV） were identified as the pathogen of the infected sweet potato, namely the synergetic infection by SPVD. Cytopathology induced by SPVD in sweet potato was also studied by TEM after ultra-thin section. Distinctive cylindrical inclusion bodies of subdivision IV were observed in mesophyll cytopalsm. Aggregates of linear virus particles arranged paralleled as bundles were also observed in mesophyll cytoplasm. All of the cytopathology above represents the infection of Potyvirus. Abnormal chloroplasts containing membrane-bound vesicles packing or encircling mitochodria were also observed. In phloem cells including sieve elements and companion cells, aggregates of linear virus particles arranged not paralleled were observed. The patterns of particle arrangement in phloem （not parallel） and in mesophyll （parallel bundles） are different. Linear virus particles distributing in phloem cell is the characteristic of Crinivirus infection. In addition, cytopathology of synergetie infection was observed in the boundary of phloem and mesophyll. This paper was the first report of SPVD outbreak in Zhejiang province.