重组型大豆花叶病毒河北分离物序列特征及侵染性

Sequence and Pathogenicity of Recombined Soybean Mosaic Virus Isolate from Hebei Province, China

重组型大豆花叶病毒(recombined soybean mosaic virus,SMV-R)是一种新SMV类型,在我国多个大豆产区广泛流行。本研究对一个重组型SMV河北分离物(HB-RS)进行全基因组测序,比较与非重组型SMV在侵染4个大豆品种后病毒浓度积累的差异。结果显示,除poly-A尾巴外,HB-RS(NCBI登录号为KR065437)由9993个核苷酸组成,包含一个开放阅读框(open reading frame,ORF),翻译后形成3202个氨基酸,系统进化分析结果显示HB-RS分离物与另外两个重组型SMV分离物聚在一组。抗性鉴定结果显示,4个品种对HB-RS和Sc6平均病情指数分别为59.5和60.5,相同大豆品种对不同的株系(分离物)可能呈现不同的症状和抗性表现,其中冀豆17对Sc6和HB-RS分别表现高抗和中抗,表明大豆对SMV的抗性存在一定的株系(分离物)专化性。此外,HB-RS在4个品种中的浓度积累均高于Sc6,在南农1138-2病毒浓度最高,达522 U,其次为五星1号(471 U)和冀黄13(199 U),最低为冀豆17,仅90 U。说明HB-RS在寄主体内更具有生存适应性,不同品种对SMV存在抗性差异。冀豆17可作为抗性品种和亲本进一步推广。

Recombined Soybean mosaic virus （SMV-R）, which is prevalent in many soybean production regions, is a novel type of SMV. To clarify the characteristics of recombinant SMV structure and pathogenicity of SMV-R, we sequenced the whole ge-nomes of a SMV-R isolate （HB-RS） from Hebei province of China, and compered the difference of SMV infection and accumula-tion in four soybean cultivars with SMV-R. The results showed that besides the poly-A tail, HB-RS consists of 9993 nucleotides, encoding only one open reading frame and 3202 amino acids. Phylogenetic analysis showed that the HB-RS isolate was clustered with other two recombined SMV isolates. Resistance identification results showed that the average disease index of four cultivars resistant to HB-RS and Sc6 was 59.5 and 60.5, respectively. The same soybean cultivar had different symptoms and resistance levels to different strains （isolates）, Jidou 17 showed high resistance to Sc6 and moderate resistance to HB-RS. These results indi-cated that soybean resistance to SMV exists strain （isolate） specialization. Additionally, the pathogenicity test showed that accu-mulation of HB-RS in four cultivars was higher than that of Sc6, indicating that HB-RS is more adaptable to the host plants. The host with highest accumulation of HB-RS was Nannong 1138-2, with 522-fold of reference virus accumulation, and the following was Wuxing 1 （471 U）, Jihuang 13 （199 U）, and Jidou 17 （only 90 U）, suggesting that HB-RS has a more survival adaptability in the soybean host. However different resistance levels to HB-RS were observed in various soybean cultivars and Jidou 17 could be used as a resistant cultivar in production or parents in further breeding.