Emaravirus属新病毒：中国枣树花叶伴随病毒全基因组测序

Full genome sequence of Chinese date mosaic-associated virus, a new member of the genus Emaravirus

摘要:

[目的]2016年以来，新疆阿克苏等地区出现了一种新的枣树病害，严重威胁当地及周边红枣产业。本研究旨在鉴定引起此次病害的病原，探究病原体的传播方式，为生物防治策略的开发提供研究基础。[方法]对发病植株进行小RNA测序以鉴定病原体；对新鉴定的病毒，通过RNAseq和反转录PCR获取病毒全序列；体外表达重组的病毒结构蛋白并制备特异性抗体，通过Western斑点杂交法在发病植株中确证病毒蛋白；收集发病区域的媒介昆虫，通过反转录PCR在昆虫体内检测病毒的基因组，鉴定可能的传毒介体。[结果]本研究鉴定一种新的欧洲山梣环斑病毒属病毒为新疆新发枣树病害可能的病原体，命名为中国枣树花叶伴随病毒（Chinese date mosaic-associated virus，CDMaV）。CDMaV是一种多分段单链RNA病毒，基因组由5条负义RNA组成；RNA1–RNA5大小分别为7160、2224、1230、1493、971nt，每条基因组RNA的互补链包含一个开放阅读框，共编码5个蛋白，依次为依赖RNA的RNA聚合酶、包膜糖蛋白、核衣壳蛋白和两个未知功能蛋白。在枣树寄生虫枣瘿螨体内扩增到病毒序列，表明该病毒可能以枣瘿螨为介体在枣树间进行传播。[结论]本研究为新疆新发枣树病害鉴定了相关病原体CDMaV，完成CDMaV全基因组测序，并鉴定枣瘿螨为可能的传毒介体。鉴定病原体和传播介体是建立病害防治方法的必要基础。

Abstract:

[Objective] A new jujube disease has emerged in Aksu and other areas in Xinjiang since 2016, seriously threatening the local and surrounding jujube industries during the last three years. This study aims to identify the causative pathogen(s) and to investigate the pathogen transmission route(s), therefore providing guides for the disease control strategies. [Methods] Small RNA sequencing was performed to identify potential pathogen(s), which revealed a new jujube virus. RNAseq and reverse transcription PCR (RT-PCR) were performed to obtain the whole genomic sequence of the identified virus. A viral protein was in-vitro expressed for antibody preparation. Western blotting with the viral specific antibody confirmed the specific existence of the viral protein in infected plants. Insects were collected in the disease-occurred areas and RT-PCR was performed to identify potential virus-transmission vector(s).[Results] This study identified a new virus, belonging to Emaravirus and named as Chinese date mosaic-associated virus (CDMaV) in this study, as a correlated causative regent for Xinjiang jujube disease. We obtained the whole genomic sequence of this viral strain. The CDMaV genome is segmented and consists of five segments of linear negative-sense and single-stranded RNA. The complete genome is 13.078 kb, with RNA1-RNA5 containing 7160 nt, 2224 nt, 1230 nt, 1493 nt, and 971 nt, respectively. The complementary strand of each genomic RNA encodes a single open reading frame, sequentially the five encoded proteins are RNA-dependent RNA polymerase, envelope glycoprotein, nucleocapsid protein, and two unknown functional proteins. The virus specific sequences could be amplified from Epitrimerus zizyphagus, indicated that CDMaV might be transmitted from infected jujube trees to the healthy plants via this insect vector. [Conclusion] This study identified CDMaV as the correlated causative agent for the newly emerged jujube disease in Xinjiang, sequenced the viral genome and identified E. zizyphagus as a potential insect vector for viral transmission. Identification of pathogen and its transmission route would efficiently guide the development of disease control strategies.