从苹果中分离的一种与我国苹果花叶病密切相关的新病毒鉴定及其致病机理研究

Accurate identification of pathogen is very important since pathogen is essential for disease control. Apple mosaic disease is one of the most serious viral diseases which plagues the apple industry. Generally, Apple mosaic virus (ApMV) is regarded as the only causal agent of apple mosaic disease. However, no researchers have detected positive for ApMV from apple leaves showing mosaic symptoms in China so far. Since we have investigated apple mosaic disease for many years in China, a novel ilarvirus, Apple necrotic mosaic virus (ApNMV), was found a high correlation with apple mosaic symptoms with a 92.1% detection rate. These results suggest that it is very obligatory to re-identify the pathogen of apple mosaic disease in China. Infectious cDNA clones of ApNMV, ApMV and Prunus necrotic ringspot virus (PNRSV) have be constructed and will be inoculated to virus-free apple seedlings (cv. 'Fuji') and cucumber (cv. ‘Suyo’) to make it clear whether this new virus is the causal agent causing apple mosaic disease in China. Analysis of transcriptomics and metabolomics will also be performed to find the differential expression of genes and secondary metabolite induced by infection of ApNMV, ApMV or PNRSV in host plants. It will elucidate the pathogenic factor and pathogenesis, reveal the origin and epidemic characteristics of apple mosaic disease in China, and have a profound meaning for the effective prevention and control of apple mosaic disease.

对病原的准确鉴定是一切病害防控的前提和基础。苹果花叶病是严重影响苹果生产的重要病毒性病害之一，传统认为ApMV是引起苹果花叶病的唯一病原，可是迄今为止均没有人从我国的苹果花叶样品中检测到苹果花叶病毒（ApMV）。本课题组发现一种新的苹果坏死花叶病毒（ApNMV）与我国的苹果花叶病高度相关，检出率高达92.1%。上述结果预示对我国苹果花叶病病原进行重新鉴定，不仅必要而且是必须。本试验利用已构建的ApNMV、ApMV以及与之亲缘关系较近的李属坏死环斑病毒（PNRSV）等三种苹果病毒的侵染性克隆接种苹果脱毒苗和四叶黄瓜，重新鉴定引起我国苹果花叶病的新的病原；并结合转录组和代谢组分析，明确三种病毒侵入寄主植物后基因的差异表达、次级代谢产物种类及含量变化。为探讨我国苹果花叶病的致病因子及其致病机理，揭示我国苹果花叶病的起源及流行传播规律，以便对症下药制定有效防控措施奠定理论基础。

苹果花叶病是严重影响苹果生产的重要病毒性病害之一，传统认为苹果花叶病毒（ApMV）是引起苹果花叶病的唯一病原，可是迄今为止均未从我国的苹果花叶样品中检测到ApMV。本研究通过高通量测序、田间检测以及嫁接试验，发现并明确了苹果坏死花叶病毒（ApNMV）是导致我国苹果花叶病的主要病原，并且发现该病毒同时也可能是山楂以及月季花叶病的主要病原。其次，明确了该病毒在我国的发生分布以及流行情况。本研究构建了ApNMV的侵染性克隆，在模式植物上接种并验证了不同发育阶段病毒含量与症状的关系；通过基因重排明确了CP在Ilarvirus系统移动中的作用。本研究还明确了健康植株与感病植株差异表达基因的筛选以及次级代谢产物种类、含量变化；最后筛选了与ApNMV CP互作的寄主因子，并利用方法进行了验证。以上结果不仅明确了我国花叶病的病原，更进一步明确了病毒侵入寄主植物后的差异表达基因和次级代谢控策略，为苹果生产过程中的病毒防控提供切实可行的建议和理论基础。

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