Cucumber mosaic virus isolated from Aconitum spp. in Japan

Viruses were isolated from leaves of plants of Aconitum species with symptoms such as mottling and yellowing in Hokkaido and Gunma prefectures in Japan. These viruses were identified as Cucumber mosaic virus (subgroup II) based on particle morphology, host range, aphid transmission, and serology.     

2b Protein is essential to induce a novel gradual cell death in Zucchini yellow mosaic virus-inoculated cucumber cotyledon co-infected with Cucumber mosaic virus

Cucumber cotyledons inoculated with Cucumber mosaic virus (CMV, Pepo strain) or Zucchini yellow mosaic virus (ZYMV, Z5-1 isolate) developed either mild chlorotic spots or no symptoms. Cotyledons treated with CMV plus ZYMV also developed mild chlorotic spots. However, plants ZYMV-inoculated cotyledons had veinal yellowing and gradual cell death by 20 days postinoculation (dpi) when co-inoculated with CMV on the other cotyledon. When analyzing this synergism, an enzyme-linked immunosorbent assay showed that CMV gradually increased in CMV-inoculated cotyledons of plants, with the other cotyledon mock- or ZYMV-inoculated. However, CMV significantly increased at 9 to 14 dpi in the ZYMV-inoculated cotyledons of plants co-infected with CMV. ZYMV similarly increased in cotyledon pairs of both co-infected and singly infected plants. Inoculation with PepoΔ2b, a modified Pepo-CMV that lacks translation of the 2b protein, revealed that PepoΔ2b without the 2b protein systemically infected cucumber but induced no symptoms on cotyledons or true leaves. Plants with a ZYMV-inoculated cotyledon and co-infected with PepoΔ2b did not undergo cell death; nevertheless, PepoΔ2b was at high levels comparable to levels of CMV in the ZYMV-inoculated cotyledon. The 2b protein thus seems essential for induction of the novel gradual cell death in ZYMV-inoculated cotyledons of cucumbers co-infected with CMV.     

Analysis of natural populations and possible natural reassortment of Cucumber mosaic virus

Plants naturally infected with Cucumber mosaic virus (CMV) were collected and analyzed by electrophoresis of the replicative form of dsRNA and by Northern blot hybridization using CMV RNA-specific probes. Some of the CMV-infected plants, especially winter crops, contained two kinds of RNA 1 segments or RNA 2 segments (or both), suggesting that mixed infections of CMV occurred naturally. Single-aphid-transmitted isolates (SATIs) from the field isolate containing two RNA 1 segments were grouped into three types by the electrophoretic mobility of RNA 1 (i.e., those containing one slow segment, those containing one fast segment, and those containing both). Furthermore, SATIs and single-lesion isolates, generated from the plants inoculated with a mixture of two CMV isolates that could be differentiated by their electrophoretic dsRNA profiles, were analyzed by dsRNA, indicating that nonparental progenies were observed. These results suggested that genetic reassortment of CMV RNA may occur in nature and that this is an important mechanism in CMV evolution.     

A Cucumber mosaic virus Isolated from Silene armeria

A Cucumber mosaic virus was newly isolated from Silene armeria and was characterized by biological, serological and molecular biological methods. Received 4 July 2001/ Accepted in revised form 28 August 2001     

Amino Acid 129 of Cucumber mosaic virus Coat Protein Determines Local Symptom Expression and Systemic Movement in Tetragonia expansa, Momordica charantia and Physalis floridana

Local symptom expression and systemic movement of Cucumber mosaic virus (CMV) in Tetragonia expansa, Momordica charantia and Physalis floridana were mapped to the amino acid at position 129 of CMV coat protein (CP), using pseudorecombinants, chimeric RNAs, a site-directed mutant of RNA 3 and four strains of CMV : pepo-, SO-, MY17- and Y-CMV. Local and systemic symptoms caused by three strains, pepo-, SO- and MY17-CMV, and those by Y-CMV differed in the three host species. The three strains expressed local chlorotic spots at 24°C and systemic chlorotic spots and ringspots at 36°C, whereas Y-CMV developed local necrotic spots at 24°C but no systemic symptoms at 36°C in T. expansa. In M. charantia the three strains caused systemic chlorotic spots, whereas Y-CMV caused local necrotic spots. The three caused systemic mosaic and Y-CMV systemic necrosis in P. floridana. With pseudorecombinants combined with pepo- and Y-CMV RNAs, CMV RNA 3 was responsible for symptom expression and systemic infection. Inoculation with Y-CMV RNA 1, RNA 2 and chimeric RNA 3s exchanged CP gene fragments between pepo- and Y-CMV showed that NruI-XhoI fragment of CP was essential for symptom expression. Comparative analysis of the NruI-XhoI fragments revealed that only the amino acid at position 129 was common among the three strains but different from that of Y-CMV. Inoculation with a point mutant constructed by substituting one nucleotide resulting in an amino acid change from Ser to Pro at position 129 in Y-CMV CP verified the previous experiments. These results indicate that the amino acid at position 129 of CMV CP is the determinant for local symptom expression and systemic movement in the three host species. CMV CP containing Ser at position 129 may induce resistant responses in these plants. Received 29 June 2001/ Accepted in revised form 28 August 2001     

侵染紫松果菊的黄瓜花叶病毒分离物鉴定

从表现黄花叶症状的紫松果菊病株上获得分离物2-1-2,电镜下可见直径约30 nm的球状病毒粒体,其与黄瓜花叶病毒抗体呈强的阳性反应,ds-RNA的谱带类型与本实验室保存的标准黄瓜花叶病毒株系相同。通过生物学、病毒粒体观察、血清学以及病毒核酸双链试验结果,确定该病毒分离物为黄瓜花叶病毒。     

<Emphasis Type="Italic">Cucumber mosaic virus</Emphasis> isolated from Amazon lily (<Emphasis Type="Italic">Eucharis grandiflora</Emphasis>)

Cucumber mosaic virus (CMV) was isolated from a mosaic diseased plant of Eucharis grandiflora. The virus caused mosaic symptoms on leaves and slight distortion of flower petals in E. grandiflora by either mechanical or aphid inoculation. The virus was identified as a strain of CMV subgroup I from its biological and serological characteristics.     

Shoot meristem tissue of tobacco inoculated with Cucumber mosaic virus is infected with the virus and subsequently recovers from infection by RNA silencing

Distribution of Cucumber mosaic virus (CMV) in shoot meristem tissue of CMV-inoculated tobacco was successively analyzed with immunohistochemical microscopy and in situ hybridization. CMV signals were detected in the tissue at 7 days postinoculation (dpi), but then they decreased and disappeared after 14dpi. Detailed observation confirmed CMV invasion of shoot apical meristem at 6–8dpi. Short interfering RNA corresponding to CMV RNAs was first detected at 7dpi and was detected up to 24dpi. These results suggest that the shoot meristem tissue is infected with CMV but subsequently recovers from the infection by RNA silencing.     

黄瓜花叶病毒浙江白术分离物全基因组序列测定与分析

正白术(Atractylodes macrocephala Koidz.)为菊科(Compositae)苍术属(Atractylodes)多年生草本植物,其根茎入药具补脾健胃、燥湿利水、止汗安胎等功效,在我国广泛栽培,并以于术(浙江临安于潜)品质最佳[1]。近年来白术生产由于品种单一,长期连作等因素导致病毒病害日趋严重。据报道,黄瓜花叶病毒(Cucumber mosaic virus,CMV)~([2])、蚕豆萎蔫病毒2号(Broad bean wilt virus 2,     

Amino acid 129 in the coat protein of Cucumber mosaic virus primarily determines invasion of the shoot apical meristem of tobacco plants

We previously reported that a strain of Cucumber mosaic virus (Pepo CMV) invaded the shoot apical meristem (SAM, tunica corpus) of tobacco plants at 6–8 days postinoculation (dpi), contrary to earlier observations. To identify a viral factor determining the ability to invade the SAM, we inoculated plants with two other CMV strains, MY17 and Y, and tested the three strains in this study. Immunohistochemical microscopy revealed that MY17 CMV invaded the SAM at 7 dpi, the same as Pepo CMV, but Y CMV did not, even at 21 dpi. Using RNA pseudorecombinants between Pepo and Y CMV, we found that Pepo RNA 2 affected the rate of SAM invasion, and Pepo RNA 3 was required for successful SAM invasion. Inoculation with RNA 1 and RNA 2 from Y CMV and RNA 3 containing the chimeric coat protein (CP) gene between Pepo and Y CMV or a Y RNA 3 point mutant containing a Ser-to-Pro substitution at position 129 in CP (Y129P) revealed that amino acid 129 of CP is the determinant for successful SAM invasion. The rate of SAM invasion of the pseudorecombinants and Y129P was consistent with the efficiency of cell-to-cell movement in the inoculated leaves, implying that SAM invasion by CMV strains may be due to efficient cell-to-cell movement.     

我国部分地区常见农作物上黄瓜花叶病毒分离物核酸多样性分析

为明确我国黄瓜花叶病毒株系分化及系统进化基本情况,从湖南、新疆、青海和海南4省区采集1 367个样品对其进行酶联免疫和RT-PCR检测,并对分离获得的15个黄瓜花叶病毒(Cucumber mosaic virus,CMV)纯化分离物CP、MP、2b核苷酸序列进行相似性和进化树分析及生物学性状比较。结果表明,辣椒、龙葵和黄瓜的CMV阳性检出率较高,分别为54.13%、29.19%和18.46%。进化树分析显示CMV-Q5与CMV亚组II的亲缘性较高;CMV-N7为新发现的重组株系,其CP、2b基因属于CMV亚组IB,MP基因却属于CMV亚组II;其余13个分离物均属于CMV亚组IB。CMV-N7和CMV-Q5在系统寄主心叶烟和枯斑寄主苋色藜上引发的症状相似,但比对照株系CMV-P3613(IB)的发病时间要晚1~2 d,系统花叶较温和,枯斑较小。表明在以上4省区常见农作物上广泛流行的CMV存在分子变异。     

Note: Occurrence and distribution ofCucumber mosaic virus infecting danshen (Salvia miltiorrhiza) in China

Cucumber mosaic virus (CMV) has resulted in much damage to Danshen (Salvia miltiorrhiza Bunge) crops in China. A 5-year survey was conducted in Hebei, Shandong, Sichuan, Shanxi, Henan and Gansu Provinces, all major Danshen-growing areas. A total of 156 Danshen plant samples with CMV symptoms were collected and tested for the presence of CMV by a double-antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) using polyclonal antibodies against CMV and a positive control, according to the supplier’s instructions (Agdia). They were confirmed to be CMV by amplification of complete coat protein gene and analysis of the gene sequence. The results showed that 122 samples were infected by CMV and all of these CMV isolates belonged to subgroup IB. http://www.phytoparasitica.org posting May 19, 2008. Joint first authors.     

First report of Melon yellow spot virus infecting balsam pear (<Emphasis Type="Italic">Momordica charantia</Emphasis> L.) in Japan

A new disease causing necrotic spots and yellowing on leaves of balsam pear (Momordica charantia) was found in Kochi Prefecture, Japan. In this study, we identified the causal pathogen as Melon yellow spot virus (MYSV) based on morphology of virus particles, serology, and the nucleotide sequence of the nucleocapsid protein gene. This is the first report of natural infection of balsam pear by MYSV. We propose the name spotted wilt for this new disease of balsam pear.     

引起甘蔗花叶病的病原分子生物学进展

花叶病是最主要的甘蔗病毒病害之一,在全球种植甘蔗的国家或地区普遍发生,可导致甘蔗产量下降,糖分减少,给甘蔗生产带来严重的经济损失。引起甘蔗花叶病的病毒主要有甘蔗花叶病毒(Sugarcane mosaic virus,SCMV)、高粱花叶病毒(Sorghum mosaic virus,Sr MV)和甘蔗条纹花叶病毒(Sugarcane streak mosaic virus,SCSMV)。本文综述了这3种病毒的生物学特性、鉴定与检测、基因组结构与基因功能、遗传变异与分子进化等方面的研究进展,并讨论了对甘蔗花叶病的生态防控措施。     

Incidence of viruses in <Emphasis Type="Italic">Alstroemeria</Emphasis> plants cultivated in Japan and characterization of <Emphasis Type="Italic">Broad bean wilt virus-2, Cucumber mosaic virus</Emphasis> and <Emphasis Type="Italic">Youcai mosaic virus</Emphasis>

Alstroemeria plants were surveyed for viruses in Japan from 2002 to 2004. Seventy-two Alstroemeria plants were collected from Aichi, Nagano, and Hokkaido prefectures and 54.2% were infected with some species of virus. The predominant virus was Alstroemeria mosaic virus, followed by Tomato spotted wilt virus, Youcai mosaic virus (YoMV), Cucumber mosaic virus (CMV), Alstroemeria virus X and Broad bean wilt virus-2 (BBWV-2). On the basis of nucleotide sequence of the coat protein genes, all four CMV isolates belong to subgroup IA. CMV isolates induced mosaic and/or necrosis on Alstroemeria. YoMV and BBWV-2 were newly identified by traits such as host range, particle morphology, and nucleotide sequence as viruses infecting Alstroemeria. A BBWV-2 isolate also induced mosaic symptoms on Alstroemeria seedlings.     

侵染百合的黄瓜花叶病毒亚组Ⅱ分离物cp基因克隆和序列分析

 从云南大理的东方型百合上得到黄瓜花叶病毒分离物(CMV-DL), ELISA检测初步确定为CMV亚组Ⅱ分离物, 设计并合成CMV亚组Ⅱ的特异引物, RT-PCR扩增得到1条约800 nt的特异片段, 经克隆及序列测定, 该片段长828 nt, 包含的外壳蛋白(CP)基因由657 nt组成。将该分离物的cp基因与其它14个CMV分离物进行同源性比较, 在核苷酸水平上与CMV亚组I和亚组Ⅱ的同源性分别为76.8%~78.1%和98.6%~99.2%;在氨基酸水平上与CMV亚组I和亚组Ⅱ的同源性分别为82.0%~84.3%和95.9%~100.0%。结果表明CMV-DL为CMV亚组Ⅱ成员。     

黄瓜绿斑驳花叶病毒海南分离物基因组测定与毒源分析

为分析2012年采自海南西瓜上具黄瓜绿斑驳花叶病毒侵染典型症状的病毒分离物CGMMV-HaiN12的分子特征和可能来源, 以病叶总RNA为模板, 分3段进行RT-PCR扩增, 测定了该分离物基因组全长序列。结果表明CGMMV-HaiN12基因组全长为6 425 bp（GenBank登录号KC852074）, 与已报道的CGMMV分离物相比, 除5′和3′端非编码区核苷酸数目略有不同外, 编码区的基因结构完全相同。CGMMV-HaiN12全基因组序列与韩国分离物AF417242的相似性为99.6%、遗传距离为0.004, 在进化树的末端两者聚为一支。将CGMMV-HaiN12与已发布的中日韩分离物的外壳蛋白基因序列进行遗传进化分析, 所有分离物在0.000~0.027的遗传距离上聚为一支, 显示这些分离物具有高度的相关性, 而与欧洲的西班牙和俄罗斯的2个代表分离物具有较大差别。在进化树末端, CGMMV-HaiN12与3个韩国分离物（AJ245440、JF838188、AF417242）、2个我国湖南分离物（JQ715592、JQ715595）聚为一支, 表明CGMMV-HaiN12可能由韩国传入, 并且与传入我国湖南的分离物高度同源。在海南本地不进行西瓜制种的情况下, 为控制CGMMV在海南的危害应加强对进入海南的西瓜和砧木种子的检疫工作。     

A new furovirus infecting barley in France closely related to the Japanese soil-borne wheat mosaic virus

In April 2001, stunted barley plants bearing mosaic symptoms were observed in a field in France (Marne Department, 51). Rod-shaped and flexuous particles were visualized by electron microscopy and positive serological reactions were detected by ELISA with Barley yellow mosaic virus (BaYMV) and Soil-borne cereal mosaic virus (SBCMV) polyclonal antisera. The tubular virus which was soil transmissible to barley cv. Esterel was separated from BaYMV by serial mechanical inoculations to barley cv. Esterel. This furo-like virus, in contrast to a French isolate of SBCMV, could be transmitted to Hordeum vulgare, Avena sativa, Beta vulgaris and Datura stramonium. RT-PCR was used to amplify the 3′-terminal 1500 nucleotides of RNA1 and the almost complete sequence of RNA2. Nucleotide and amino acid sequence analyses revealed that the French virus infecting barley is closely related to a Japanese isolate of Soil-borne wheat mosaic virus (SBWMV-JT) which was originally isolated from barley. This French isolate was named SBWMV-Mar. The 3′ UTRs of both RNAs can be folded into tRNA-like structures which are preceded by a predicted upstream pseudoknot domain with seven and four pseudoknots for RNA1 and RNA2, respectively. The four pseudoknots strongly conserved in RNAs 1 and 2 of SBWMV-Mar show strong similarities to those described earlier in SBWMV RNA2 and were also found in the 3′ UTR of Oat golden stripe virus RNAs 1 and 2 and Chinese wheat mosaic virus RNA2. Sequence analyses revealed that the RNAs 2 of SBWMV-Mar and -JT are likely to be the product of a recombination event between the 3′ UTRs of the RNAs 2 of SBWMV and SBCMV. This is the first report of the occurrence of an isolate closely related to SBWMV-JT outside of Japan.