Characterization of Synergy Between Cucumber mosaic virus and Potyviruses in Cucurbit Hosts

ABSTRACT Mixed infections of cucurbits by Cucumber mosaic virus (CMV) and potyviruses exhibit a synergistic interaction. Zucchini squash and melon plants coinfected by the potyvirus Zucchini yellow mosaic virus (ZYMV) and either Fny-CMV (subgroup IA) or LS-CMV (subgroup II) displayed strong synergistic pathological responses, eventually progressing to vascular wilt and plant death. Accumulation of Fny- or LS-CMV RNAs in a mixed infection with ZYMV in zucchini squash was slightly higher than infection with CMV strains alone. There was an increase in CMV (+) strand RNA levels, but no increase in CMV (-) RNA3 levels during mixed infection with ZYMV. Moreover, only the level of capsid protein from LS-CMV increased in mixed infection. ZYMV accumulated to similar levels in singly and mixed infected zucchini squash and melon plants. Coinfection of squash with the potyvirus Watermelon mosaic virus (WMV) and CMV strains increased both the Fny-CMV RNA levels and the LS-CMV RNA levels. However, CMV (-) strand RNA3 levels were increased little or not at all for CMV on coinfection with WMV. Infection of CMV strains (LS and Fny) containing satellite RNAs (WL47-sat RNA and B5*-sat RNA) reduced the accumulation of the helper virus RNA, except when B5*-sat RNA was mixed with LS- CMV. However, mixed infection containing ZYMV and the CMV strains with satellites reversed the suppression effect of satellite RNAs on helper virus accumulation and increased satellite RNA accumulation. The synergistic interaction between CMV and potyviruses in cucurbits exhibited different features from that documented in tobacco, indicating there are differences in the mechanisms of potyvirus synergistic phenomena.     

Biological characterization of Tomato leaf curl New Delhi virus from Spain

Tomato leaf curl New Delhi virus (ToLCNDV; family Geminiviridae, genus Begomovirus) is an emerging virus in horticulture crops in Asia, and has recently been introduced in Spain, Tunisia and Italy. No betasatellite DNA was detected in infected tomato and zucchini squash samples from Spain, and agroinoculated viral DNA‐A and DNA‐B were sufficient to reproduce symptoms in plants of both crop species. Infected tomato and zucchini squash plants also served as inoculum sources for efficient transmission either mechanically or using Bemisia tabaci whiteflies. Cucumber, melon, watermelon, zucchini squash, tomato, eggplant and pepper, but not common bean, were readily infected using viruliferous whiteflies and expressed symptoms 8–15 days post‐inoculation. New full‐length sequences from zucchini squash and tomato indicated a high genetic homogeneity (>99% sequence identity) in the ToLCNDV populations in Spain, pointing to a single recent introduction event.     

Transmissibility of Cucumber mosaic virus by Aphis gossypii Correlates with Viral Accumulation and Is Affected by the Presence of Its Satellite RNA

ABSTRACT Satellite RNAs (satRNAs) are associated with Cucumber mosaic virus (CMV) in tomato, most often causing severe epidemics of necrotic plants, and not associated with specific host symptoms. Laboratory studies on virus transmission by the aphid vector Aphis gossypii were performed to better understand the dynamics of field populations of CMV. The presence of satRNAs correlated with lower concentrations of virus in infected plants and with a decrease in the efficiency of transmission from satRNA-infected plants. Both the concentration of virus in CMV-infected tomato and the efficiency of transmission varied more extensively with nonnecrogenic satRNAs than with necrogenic satRNAs. A negative effect of satRNAs on virus accumulation can account, in part, for a decrease in the field transmission and recovery of CMV + satRNAs. Aphids behaved differently and probed less readily on plants infected with CMV + necrogenic satRNAs compared with plants containing non-necrogenic satRNAs. Aphid-mediated satRNA-free CMV infections were observed in test plants when aphids were fed on source plants containing CMV + nonnecrogenic satRNA; no comparable satRNA-free test plants occurred when aphids were fed on source plants containing necrogenic satRNAs. These results indicate that factors associated with transmission can be a determinant in the evolution of natural populations of CMV and its satRNA.     

Yellowing disease in zucchini squash produced by mixed infections of Cucurbit yellow stunting disorder virus and Cucumber vein yellowing virus

Zucchini squash is host to Cucurbit yellow stunting disorder virus (CYSDV), a member of the genus Crinivirus, and Cucumber vein yellowing virus (CVYV), a member of the genus Ipomovirus, both transmitted by the whitefly Bemisia tabaci. Field observations suggest the appearance of new symptoms observed on leaves of zucchini squash crops when both viruses were present. When infected during controlled experiments with CYSDV only, zucchini plants showed no obvious symptoms and the virus titer decreased between 15 and 45 days postinoculation (dpi), after which it was no longer detected. CVYV caused inconspicuous symptoms restricted to vein clearing on some of the apical leaves and the virus accumulated progressively between 15 and 60 dpi. Similar accumulations of virus followed single inoculations with the potyvirus Zucchini yellow mosaic virus (ZYMV) and plants showed severe stunting, leaf deformation, and mosaic yellowing. However, in mixed infections with CYSDV and CVYV, intermediate leaves showed chlorotic mottling which evolved later to rolling, brittleness, and complete yellowing of the leaf lamina, with exception of the veins. No consistent alteration of CVYV accumulation was detected but the amounts of CYSDV increased ≈100-fold and remained detectable at 60 dpi. Such synergistic effects on the titer of the crinivirus and symptom expression were not observed when co-infected with ZYMV.     

黄瓜花叶病毒甜菜分离物的分离鉴定

 从新疆石河子地区春季采种甜菜和夏播母根用甜菜上分离到3个病毒分离物,代号为石-B-2、石-B-5和石-B-D,自然感染甜菜引起叶片黄色花叶、扭曲、皱缩和植株严重矮化。病毒粒体球状、直径28~30 nm、均含有分子量约为2 9k D外壳蛋白、3种相同的较大片段的双链RNA (即3400 bp的RNA1、3100 bp的RNA₂、2300 bp的RNA₃)和片段大小约400 bp的小RNA,石-B-2和石-B-D具有1100 bp的RNA4,在ELISA和琼脂双扩散试验中,3个分离物均与CMV-83抗血清有特异反应,初步认为这3个球状病毒分离物属于CMV,但它们具有狭窄的寄主范围,不感染心叶烟、蔓陀罗、番茄,在寄主反应、双链RNA4和卫星RNA的大小上明显不同于国内外报道的CMV株系或分离物,同时说明侵染甜菜的CMV可能存在着株系分化。     

携带eGFP的ZYMV侵染性克隆的构建及其侵染性

 小西葫芦黄花叶病毒(zucchini yellow mosaic virus,ZYMV)是瓜类作物主要病毒之一,严重威胁瓜类产业的可持续发展。本研究在ZYMV 甜瓜分离物CH-87侵染性克隆基础上,利用同源重组策略在NIb和CP编码序列之间插入了eGFP,命名为pXT1-ZYMV-eGFP。将pXT1-ZYMV-eGFP转化农杆菌并接种西瓜和甜瓜,结果发现pXT1-ZYMV-eGFP可以系统侵染西瓜和甜瓜,引起典型的花叶症状,在紫外灯下发病植株呈现绿色荧光。经摩擦接种证实,该克隆接种后所产生的病毒子代可以稳定的传播繁殖。研究表明携带eGFP的ZYMV侵染性克隆成功构建,可用于该病毒致病性及病毒与寄主互作的相关研究。     

Accumulation of short interfering RNAs characteristic of RNA silencing precedes recovery of tomato plants from severe symptoms of <Emphasis Type="Italic">Potato spindle tuber viroid</Emphasis> infection

Tomato plants infected with Potato spindle tuber viroid (PSTVd) had severe leaf curling and vein necrosis. The disease symptoms began to diminish during the late stages of infection, however, and almost healthy-looking leaves began to appear on the upper portion of the plants. PSTVd concentrations reached their highest levels in leaves with severe symptoms and decreased in upper leaves recovering from severe symptoms. PSTVd-specific short interfering RNAs (siRNAs), characteristic of RNA silencing, accumulated in all leaves in which PSTVd reached a detectable level, suggesting that recovery from severe disease was induced by RNA silencing via sequence-specific degradation of PSTVd.     

Effect of two satellite RNAs on Nicotiana glutinosa infected with Cucumber mosaic virus (CMV)

Two types of satellite RNAs (XJs1 and XJs2) were found to be associated with the two Cucumber mosaic virus (CMV) beet isolates XJ1 and XJ2 consisting of 384 nucleotides and 336 nucleotides, respectively. Our work showed that XJs1 and XJs2 could attenuate symptoms on Nicotiana glutinosa induced by CMV and the effect of XJs1 on symptoms was stronger than XJs2. Co-inoculation of CMV with XJs1 produced lighter oxidative stress than that with XJs2. Oxygen uptake rates through the alternative pathway in leaves infected with CMV and XJs2 were always higher than that with CMV and XJs1 and lower than infection with CMV alone. The non-photochemical fluorescence quenching (qN) increased more in N. glutinosa infected with CMV and XJs2 than that with CMV and XJs1. The relationship among helper virus, satRNAs and the host plants is discussed. Two closely-related satRNAs from the same plant has not been reported so far. The effects of these two satRNAs on virus-infected N. glutinosa were significantly different. The difference may be caused by deletion and mutation of the satRNAs.     

西葫芦环斑病病原鉴定及葫芦科作物对西瓜花叶病毒抗性筛选

 西瓜花叶病毒(watermelon mosaic virus,WMV)是危害我国葫芦科作物生产的重要病原。培育和种植抗病品种是防治病毒病最经济有效的措施。本研究利用RT-PCR和血清学方法在表现环斑症状的西葫芦果实上检测到WMV,未检测到番木瓜环斑病毒(papaya ringspot virus,PRSV)。接种WMV侵染性克隆到西葫芦品种绿源冬宝,果实表面产生环斑症状,表明WMV是引起西葫芦果实表面环斑症状的重要病原。利用间接ELISA方法对山东泰安的西瓜、黄瓜、甜瓜、西葫芦和南瓜等46个样品检测发现33个样品表现WMV血清学阳性(检出率71.74%),薛庄采集的带有环斑症状的西葫芦均检测到WMV。对山东省81份葫芦科作物种质资源抗WMV鉴定发现西葫芦品种万盛丰宝、盛丰金珠表现中抗(MR);西瓜品种绿宝新秀和浪潮一号表现中抗(MR);甜瓜品种黄皮面瓜表现抗病(R);黄瓜品种星君贝贝表现中抗(MR);南瓜品种爱维80南瓜表现高抗(HR),蜜本南瓜、传统蜜本南瓜、七叶早南瓜、玲珑二号和绿贝贝迷你南瓜等5个品种表现抗病(R);瓠瓜品种均表现为感病(S)。研究结果对合理布局葫芦科作物品种防控WMV具有重要意义。     

甘肃省南瓜及西葫芦小西葫芦黄花叶病毒病鉴定

利用双抗夹心酶联免疫吸附测定(DAS-ELISA)的方法对甘肃出入境南瓜、西葫芦种子及采自河西地区显症病株叶片进行检测,在种子及病叶组织中均检测到ZYMV病毒,其中南瓜种子带毒批次占12.5%,西葫芦种子带毒批次占11.8%。根据已报道的小西葫芦黄花叶病毒(Zucchini yellow mosaic virus)基因组核苷酸序列,设计引物扩增其外壳蛋白(CP)基因,以ELISA阳性种子或病叶组织总RNA为模板,进行RT-PCR扩增,对预期大小的扩增产物进行测序,结果表明扩增获得的核苷酸序列与世界各地的ZYMV分离物CP基因具有高度一致性,综合ELISA检测和RT-PCR的结果,确定南瓜、西葫芦种子可携带ZYMV,且ZYMV是侵染甘肃瓜类作物的重要病毒种类。     

福建西番莲病毒病的发生及其病原黄瓜花叶病毒亚组鉴定

1988～1995年对福建西番莲病毒病的发生为害进行调查,发现在西番莲栽培区病毒病普遍发生,发病率通常在30％～40％,严重的达90％以上。田间症状主要表现为叶片环斑、皱缩、花叶、环斑花叶,死顶和果实木质化等。从田间病株采集40份样本,经电镜观察和采用A蛋白夹心ELISA(PAS-ELISA),用西番莲木质化病毒(PWV)、西番莲黄花叶病毒(PFYMV)、紫果西番莲花叶病毒(GMV)、烟草花叶病毒(TMV)及黄瓜花叶病毒(CMV)的抗血清进行测定,其中36个样本检测出CMV,表明福建西番莲病毒病的主要病原为CMV。与此同时,对西番莲上CMV进行亚组鉴定,采用鉴别寄主和单、多克隆抗体双夹心ELISA(DAS-ELISA)对36个CMV阳性样本进行测定,结果35个属CMV亚组Ⅰ,1个属CMV亚组Ⅱ,表明田间以CMV亚组Ⅰ分离物占绝对优势。     

Severe mosaic caused by zucchini yellow mosaic virus in cucurbits from Jordan

A virus disease causing severe mosaic in melon (the melon isolate) was identified as a strain of zucchini yellow mosaic virus (ZYMV). Identification was based on host range, aphid transmissibility, electron microscopy, and serological tests. The virus was recovered from all cultivated cucurbits in Jordan and from naturally infected Moluccella laevis. It was seed-transmitted in Ranunculus sardous. Host-range comparison showed that the melon isolate and a French isolate belong to a different biotype group from a Connecticut isolate (ZYMV-CT); this was confirmed by indirect ELISA. During 1987–1988. ZYMV appeared to be the predominant virus affecting cucurbits.     

番茄褪绿病毒病在山东设施西葫芦上的发生及潜在危害

番茄褪绿病毒tomato chlorosis virus (ToCV)是我国蔬菜生产的重要新发病毒,其寄主范围逐年扩大。2019年10月项目组在山东寿光西葫芦温室调查时发现部分叶片呈现黄化、脉间褪绿,类似于ToCV侵染症状,并伴有烟粉虱发生。利用特异性引物检测发现,扩增的目的片段与GenBank中登录的侵染番茄的ToCV基因序列(登录号：KC887998.1)同源性高达99.58%,充分说明西葫芦植株已被ToCV侵染。通过对病毒病发生规律和烟粉虱虫口数量调查发现,西葫芦定植后1个月表现侵染症状的植株为2.0%,定植后2个月达到4.2%,定植后4个月后高达68.2%,病毒发生呈指数增长,而烟粉虱虫口数量却维持较低密度。从济南和德州采集的西葫芦疑似病叶和烟粉虱中也检出ToCV病毒,说明该病毒可能已经在山东省设施西葫芦主要种植区普遍发生,并经烟粉虱广泛传播,需引起高度重视。     

A Cucumber mosaic virus isolated from Momordica charantia L.

Momordica charantia L. plants systemically infected with Cucumber mosaic virus (CMV) were found in Oita Prefecture. The virus isolated from the host plant was characterized by biological, serological, and molecular biological methods. The purified virus was used to mechanically inoculate the host and produced green mottle, green mosaic, and/or chlorotic spots in the noninoculated upper leaves of the host. The virus was identified as an isolate of CMV containing genomic RNA3 derived from subgroup IA by several lines of evidence based on electron microscopy, serological detection, host range, symptoms, and the entire nucleotide sequence of RNA3.     

Patterns in disease progress and the influence of single and multiple viral infections on pepper (<Emphasis Type="Italic">Capsicum annuum</Emphasis> L.) growth

The patterns and progress of disease caused by multiple infections of Cucumber mosaic virus (CMV), Pepper mild mottle virus (PMMoV) and Pepper mottle virus (PepMoV) and their effects on growth of pepper plants (Capsicum annuum L.) were investigated in this study. Each virus induced distinct symptoms, but more severe symptoms, including reduced growth rates, were observed when pepper plants were simultaneously infected by more than one virus. When CMV was included in multiple viral inoculations, co-inoculations and sequential inoculations, PepMoV and PMMoV symptoms were observed but the symptoms characteristic of CMV were not masked, even though CMV titre did not increase greatly. In multiple viral infections, PepMoV titre and CMV did not increase significantly, but PMMoV titre gradually increased in most cases. Growth rates of pepper plants were greatly reduced during the 30 to 40-day post-inoculation period under both single-infection and multiple-infection conditions, but multiple viral infections of CMV pre-inoculated peppers were affected to a greater extent. A significant reduction in fruit size and fruit number was observed in single and multiple viral inoculations, and fruit malformation rates were high in CMV single-infection and multiple viral infections with CMV.     

豌豆病毒病病原研究

 1986年至1990年,从豌豆田中采集了150余份病毒病样本,鉴定出蚕豆萎蔫病毒(BB-WV)、芜菁花叶病毒(TuMV)、马铃薯Y病毒组分离物、黄瓜花叶病毒(CMV)、莴苣花叶病毒(LMV)、大豆花叶病毒(SMV)、豌豆花叶病毒(PMV)、菜豆黄花叶病毒(BYMV)和苜蓿花叶病毒(AMV)等9种病毒。样本中,BBWV所占的比例最高,达59.2%,其次为CMV,占15.5%。BBWV常与CMV复合侵染豌豆,LMV发生也较普遍。田间调查表明,豌豆病毒病发病率因种植地区及品种不同而有差异,平均发病率为12.4%。     

Identification and characterization of peanut stunt cucumovirus from naturally infected alfalfa in Iran

A mechanically transmissible virus was isolated from a naturally infected alfalfa plant ( Medicago sativa ) in Karaj, Iran. It induced fern-leaf symptoms in Lycopersicon esculentum , general chlorosis and stunting in Arachis hypogoea , local lesions and systemic infection in Chenopodium quinoa , Phaseolus vulgaris and Vigna unguiculata but only local lesions in C. amaranticolor . In gel-immunodiffusion tests, it reacted strongly with an antiserum to peanut stunt cucumovirus (PSV), moderately with two of six antisera to cucumber mosaic cucumovirus (CMV) and with two of five antisera to tomato aspermy cucumovirus. Its spherical virions (28 nm in diameter) contained a coat protein of approximately 29 kDa and encapsidated four species of RNAs with similar electrophoretic mobilities to RNAs 1–4 of CMV strains Fny and LS and those of PSV strains J and W. Its encapsidated RNAs hybridized in slot-blot hybridization assay with the complementary DNA probe of PSV-W RNAs but not with those of CMV strains. Therefore, on the basis of biological, serological and physico-biochemical properties, the virus was identified as PSV. No satellite RNA was associated with the virus. This is the first report of PSV in Iran.     

高通量测序发现河南开封、中牟西瓜病毒病由多种病毒复合侵染导致

 调查发现河南省开封市祥符区和郑州市中牟县西瓜田病毒病严重发生,症状表现为叶片黄化、蕨叶、皱缩、卷曲,枝梢翘起,果实变小和瓜纹不清。为明确其病毒种类,通过小RNA测序及生物信息学分析发现采集的西瓜样本中存在8种病毒。其中包括5种已知病毒:小西葫芦黄花叶病毒(Zucchini yellow mosaic virus, ZYMV)、甜瓜蚜传黄化病毒(Melon aphid-borne yellows virus, MABYV)、西瓜花叶病毒(Watermelon mosaic virus, WMV)、黄瓜绿斑驳花叶病毒(Cucumber green mottle mo-saic virus, CGMMV)和西瓜隐潜病毒(Citrullus lanatus cryptic virus, CiLCV);3种为新检出的RNA病毒:西瓜病毒A(Watermelon virus A, WVA)、西瓜皱叶相关病毒1号(Watermelon crinkle leaf-associated virus 1, WCLaV-1)和西瓜皱叶相关病毒2号(Watermelon crinkle leaf-associated virus 2, WCLaV-2)。RT-PCR检测田间66个西瓜标样发现,WMV、CiLCV和ZYMV是侵染两地西瓜的主要病毒,其阳性检出率分别为61%、56%和52%,两种及以上病毒复合侵染的比率达68%。