我国发现由甘薯褪绿矮化病毒和甘薯羽状斑驳病毒协生共侵染引起的甘薯病毒病害

甘薯病毒病害(Sweet potato virus disease,SPVD)是由毛形病毒属(Crinivirus)的甘薯褪绿矮化病毒(Sweet potato chlorotic stunt virus,SPCSV)和马铃薯Y病毒属(Potyvirus)的甘薯羽状斑驳病毒(Sweet potato feathery mottle virus,SPFMV)协生共侵染甘薯引起的病毒病害[1].     

Interactions between a crinivirus, an ipomovirus and a potyvirus in coinfected sweetpotato plants

Novel and severe symptoms of chlorosis, rugosity, leaf strapping and dark green islands, designated as sweetpotato severe mosaic disease (SPSMD), were caused by dual infection of Sweet potato mild mottle virus (SPMMV; Ipomovirus ) and Sweet potato chlorotic stunt virus (SPCSV; Crinivirus ) in three East African sweetpotato cultivars (Tanzania, Dimbuka and New Kawogo). The storage root yield was reduced by ∼80%, as compared with healthy plants under screenhouse conditions in Uganda. Plants infected with SPMMV or SPCSV alone showed nonsignificant or 50% yield reduction, respectively. SPCSV reduced resistance to SPMMV in sweetpotato, similar to the situation with resistance to Sweet potato feathery mottle virus (SPFMV; Potyvirus ) that breaks down following infection with SPCSV, followed by development of sweet potato virus disease (SPVD). In single virus infections with SPMMV and SPFMV or their coinfection, cvs Tanzania and Dimbuka were initially systemically infected, displayed symptoms and contained readily detectable virus titres, but new leaves were symptomless with very low virus titres, indicating recovery from disease. In contrast, cv. New Kawogo remained symptomless and contained low SPMMV and SPFMV titres following graft inoculation. These moderate and high levels of resistance to SPMMV and SPFMV, respectively, were lost and cultivars succumbed to a severe disease following coinfection with SPCSV. The synergistic interactions increased titres of SPMMV and SPFMV RNA by ∼1000-fold as quantified by real-time PCR, whereas SPCSV titres were reduced twofold, indicating an antagonistic interaction. Coinfection with SPMMV and SPFMV caused no detectable changes in virus titres or symptom severity.     

Two Serotypes of Sweetpotato feathery mottle virus in Uganda and Their Interaction with Resistant Sweetpotato Cultivars

ABSTRACT Isolates of Sweetpotato feathery mottle virus (SPFMV, genus Potyvirus, family Potyviridae) were obtained in several districts of Uganda from sweetpotato plants infected with the sweetpotato virus disease (SPVD), the most important disease of this crop in Africa. A monoclonal antibody (MAb 7H8) raised against the coat proteins (CP) of a mixture of the SPFMV strain C (United States) and the isolate SPV-I (West Africa) distinguished Ugandan SPFMV isolates into those detectable and not detectable by the MAb. These two serotypes differed in prevalence in different districts of Uganda and in two common sweetpotato cultivars. Both serotypes could be transmitted simultaneously by single aphids. The serotypes differed in their ability to systemically coinfect sweetpotatoes that were infected with Sweetpotato chlorotic stunt virus (SPCSV, genus Crinivirus), the virus required to induce SPVD in SPFMV-infected plants. One sweetpotato breeding line, resistant to SPFMV from the New World, was infected by graft-inoculation with all SPFMV isolates from Uganda. Another SPFMV-resistant sweetpotato line became infected with SPFMV and developed SPVD only following coinoculation with SPCSV.     

Incidence of five viruses infecting sweetpotatoes in Uganda; the first evidence of Sweet potato caulimo-like virus in Africa

In a survey of most sweetpotato-growing areas of Uganda, virus-like diseases were observed in all districts surveyed. Out of 338 fields sampled in 35 of the then 42 districts, 219 (65%) had some plants with symptoms. The most common symptoms included vein clearing, mottling, leaf distortion, yellowing, stunting and leaf strapping. Particularly high virus-like disease incidences (means of 34–86%) were encountered in districts around Lake Victoria and in the Rift Valley in southern and western parts of Uganda; particularly low incidences were encountered in the east and north of Uganda. Using four formats of enzyme-linked immunosorbent assay in combination with immunoelectron microscopy and polymerase chain reaction assays, five viruses were identified. Sweet potato feathery mottle virus (SPFMV) and Sweet potato chlorotic stunt virus (SPCSV) were most commonly detected, being found in about 90% of samples. Sweet potato mild mottle virus at 10%, Sweet potato chlorotic fleck virus (SPCFV) at 8% and Sweet potato caulimo-like virus (SPCaLV) at 0·07% were more rarely detected. Most infections were multiple, SPCSV + SPFMV constituting > 90% of all double infections. Triple infections, involving mainly SPFMV, SPCSV and either SPMMV or SPCFV, and quadruple infections of SPFMV + SPCSV + SPMMV + SPCFV were observed in < 10% of the diseased samples. The identification of SPCaLV is the first evidence of its occurrence in Africa.     

Degeneration in sweetpotato due to viruses,virus‐cleaned planting material and reversion: a review

This review examines viral degeneration in sweetpotato in different regions of the World, particularly that caused by Sweet potato chlorotic stunt virus (SPCSV) and Sweet potato feathery mottle virus (SPFMV), comparing impacts on yield in single and complex infections of all the major viruses affecting the crop. How cultivars are generated and virus resistance are also covered, especially for Africa. The synergistic (SPCSV + SPFMV) sweet potato virus disease (SPVD) is amongst the most dramatic diseases of sweetpotato but its overall yield impacts may not be as high as is generally assumed. It is constrained by resistance, roguing and selection of symptomless planting material. Instead, the cumulative impact of individual and combinations of symptomless viruses may be globally greater. These include sweepoviruses and various potyviruses, of which the commonest is SPFMV. A number of aspects of virus‐cleaned planting stocks are identified, including reinfection rates, that need investigating before their use is considered as sustainable in developing countries. Popular East African cultivars appear to sustain their long‐term survival by reverting from symptomless infection. The likely biochemistry of this is discussed, and parallels are drawn with other crops. It is concluded that breeding for this attribute will be the best strategy for achieving long‐term control of most sweetpotato viruses.     

国家种质广州甘薯圃病毒种类鉴定及分析

为明确引起国家种质广州甘薯资源圃中病毒病的病毒种类及优势种,为甘薯种质安全保存提供支持,2017年从甘薯资源圃中未脱毒更新的盆栽苗和大田苗中采集155份具有不同病毒病症状的甘薯资源样品,利用PCR和RT-PCR检测技术对这些样品进行了17种病毒的分子检测.155份样品均有病毒检出,包括甘薯羽状斑驳病毒Sweet pot...     

中国甘薯病毒种类的血清学和分子检测

 2009～2010年,从我国18个省（市）采集了176份表现病毒病症状的甘薯样品。利用血清学、PCR和核苷酸序列测定的方法,对上述样品中的病毒种类进行了鉴定。血清学检测结果表明,供试样品中甘薯羽状斑驳病毒（SPFMV）的阳性率最高,达56.3%,其次为甘薯G病毒（SPVG）和甘薯类花椰菜花叶病毒(SPCaLV),阳性率分别为34.1%和33.5%。PCR和核苷酸序列测定结果表明,我国甘薯上至少存在SPFMV、SPVG、甘薯潜隐病毒（SPLV）、甘薯褪绿斑病毒（SPCFV）、甘薯褪绿矮化病毒（SPCSV）、黄瓜花叶病毒（CMV）、甘薯脉花叶病毒（SPVMV）和甘薯卷叶病毒（SPLCV）8种病毒。此外,供试样品中没有检测出甘薯轻斑驳病毒（SPMMV）,是否存在甘薯轻斑点病毒(SPMSV)、SPCaLV和C 6病毒尚不能确定。     

Detection and elimination of viruses infecting sweet potatoes in Hungary

Sweet potato has been grown in Hungary for the last three decades, and its popularity is increasing among farmers and consumers. Its production is hampered by pests and diseases due to poor agricultural practices, such as the use of virus-infected propagation materials. We tested the presence of 15 viruses by PCR and quantitative PCR in 110 sweet potato plants collected from seven regions in Hungary. Seven viruses in single or multiple infections associated with a wide range of foliar symptoms were detected: sweet potato chlorotic stunt virus (SPCSV), sweet potato virus G (SPVG), sweet potato virus C (SPVC), sweet potato feathery mottle virus (SPFMV), sweet potato virus 2 (SPV2), sweet potato leaf curl virus (SPLCV), and sweet potato pakakuy virus (SPPV). This is the first report on the occurrence of the begomovirus SPLCV in sweet potatoes in Hungary. The infectivity and identity of these viruses were confirmed through bioassays (grafting to Ipomoea setosa) and sequencing of the PCR-amplified sections of their genomes, respectively. Due to the necessity for virus-free sweet potato propagation material in Hungary, virus elimination was carried out successfully in five out of six genotypes important for Hungarian farmers using heat treatment and meristem tip culture. All five viruses detected in the plants before heat treatment were removed except SPPV, which persists after heat treatment. Production and strict regulation of virus-free sweet potato propagation materials are recommended to avoid exacerbating the virus situation and protect Hungarian farmers from further losses.     

利用小RNA测序技术鉴定吉林省甘薯病毒

在吉林省7个主要甘薯种植区共采集85份甘薯叶片样品,利用小RNA深度测序技术对混合样品进行检测,经RT-PCR和测序验证,鉴定出样品中存在10种病毒,包括6种RNA病毒和4种DNA病毒。分别是马铃薯Y病毒科马铃薯Y病毒属的甘薯羽状斑驳病毒Sweet potato feathery mottle virus (SPFMV)、甘薯潜隐病毒Sweet potato latent virus (SPLV)、甘薯G病毒Sweet potato virus G (SPVG)、甘薯C病毒Sweet potato virus C (SPVC)、甘薯2号病毒Sweet potato virus 2 (SPV2);长线形病毒科毛形病毒属的甘薯褪绿矮化病毒Sweet potato chlorotic stunt virus (SPCSV);双生病毒科菜豆金色花叶病毒属的甘薯曲叶病毒Sweet potato leaf curl virus(SPLCV);玉米线条病毒属的甘薯无症状1号病毒Sweet potato symptomless virus 1 (SPSMV1);花椰菜花叶病毒科杆状DNA病毒属的甘薯杆状DNA病毒B Sweet potato badnavirus B (SPBV-B)和甘薯隐症病毒Sweet potato pakakuy virus (SPPV)。     

山东甘薯主要病毒的鉴定及多样性分析

为明确山东省甘薯病毒病发生现状,在重病区调查采样,通过鉴别寄主、电镜和分子检测技术明确主要病毒种类;并克隆病毒外壳蛋白基因序列,利用Mega 5.0构建系统进化树进行遗传分析。结果显示,巴西牵牛嫁接甘薯染病枝条后叶片黄化、褪绿及皱缩;病样组织中存在大量600~900 nm的线状病毒粒子和柱状内含体。24份病样中检测到甘薯羽状斑驳病毒、甘薯潜隐病毒、甘薯G病毒、甘薯曲叶病毒和甘薯褪绿矮化病毒5种病毒,其中23份为复合侵染,存在11种侵染类型。遗传分析显示山东省甘薯羽状花叶病毒主要为EA、O和C株系,甘薯潜隐病毒与周边省份分离物相近,甘薯G病毒与中国海南和美国分离物相近,甘薯曲叶病毒分属3个株系。表明山东地区甘薯病毒种类繁多,侵染模式复杂,病毒遗传结构具有多样性。     

Effect of local inoculum on the spread of sweet potato virus disease: limited infection of susceptible cultivars following widespread cultivation of a resistant sweet potato cultivar

A study compared the spread of sweet potato virus disease (SPVD) into crops of two moderately resistant and initially SPVD-free sweet potato cultivars in northern and southern Mpigi, Uganda. Whiteflies, the vector of sweet potato chlorotic stunt crini virus (SPCSV), a component cause of SPVD, were similarly abundant in farmers' sweet potato fields around Namulonge in northern Mpigi, and Kanoni in southern Mpigi. However, mean incidence of SPVD in farmers' crops neighbouring the trials was higher at Kanoni (13.3%) than at Namulonge (2.8%). Furthermore, spread of SPVD into initially SPVD-free sweet potato plots of two only moderately resistant cultivars was greater in plots at Kanoni than in plots at Namulonge. The SPVD-resistant New Kawogo was the most common cultivar grown in farmers' fields at Namulonge and had few diseased plants, whereas susceptible cultivars with relatively high incidences of disease predominated at Kanoni. Final SPVD incidence in each trial was positively correlated with a measure combining the proximity and level of inoculum in surrounding fields. The study demonstrates the importance of local SPVD inoculum in determining the rate of spread of the disease into fields and implies that the widespread cultivation of a resistant variety limits infection of susceptible cultivars grown nearby.     

Natural wild hosts of sweet potato feathery mottle virus show spatial differences in virus incidence and virus-like diseases in Uganda

Sweet potato feathery mottle virus (SPFMV, genus Potyvirus) is globally the most common pathogen of sweetpotato. An East African strain of SPFMV incites the severe 'sweetpotato virus disease' in plants co-infected with Sweet potato chlorotic stunt virus and threatens subsistence sweetpotato production in East Africa; however, little is known about its natural hosts and ecology. In all, 2,864 wild plants growing in sweetpotato fields or in their close proximity in Uganda were observed for virus-like symptoms and tested for SPFMV in two surveys (2004 and 2007). SPFMV was detected at different incidence in 22 Ipomoea spp., Hewittia sublobata, and Lepistemon owariensis, of which 19 species are new hosts for SPFMV. Among the SPFMV-positive plants, approximately 60% displayed virus-like symptoms. Although SPFMV incidence was similar in annual and perennial species, virus-like diseases were more common in annuals than perennials. Virus-like diseases and SPFMV were more common in the eastern agroecological zone than the western, central, and northern zones, which contrasted with known incidence of SPFMV in sweetpotato crops. The data on a large number of new natural hosts of SPFMV detected in this study provide novel insights into the ecology of SPFMV in East Africa.     

A more sensitive and rapid multiplex RT-PCR assay combining with magnetic nanobeads for simultaneous detection of viruses in sweet potato

An improved multiplex RT-PCR assay combined with magnetic nanobeads (MNB-RT-PCR) was developed for simultaneous detection of four sweet potato viruses, Sweet potato virus G (SPVG), Sweet potato feathery mottle virus (SPFMV), Sweet potato virus C (SPVC) and Sweet potato chlorotic fleck virus (SPCFV). Four primer pairs specific for each virus were designed and the corresponding PCR products were 169, 357, 516 and 900 bp in length for SPVG, SPFMV, SPVC and SPCFV, respectively. The specificity of the method was tested using different combinations of virus templates, and the identities of the amplification products were confirmed by sequencing. The limits of detection for all four viruses by single and multiplex MNB-RT-PCR assays were comparable. The assay was further evaluated using laboratory and field samples compared with a conventional CTAB-RT-PCR assay, and the comparative results showed that the MNB-RT-PCR assay was more rapid and sensitive. These results suggest that the multiplex MNB-RT-PCR assay is an effective and preferable method for virus detection in sweet potato.     

Effects of sweet potato feathery mottle virus and sweet potato sunken vein virus on sweet potato yields and rates of reinfection of virus-Free planting material in Israel

Yield reductions ofca 50% or more were observed in field plots infected with both sweet potato feathery mottle virus (SPFMV) and sweet potato sunken vein virus (SPSVV) (‘complex’), compared with plots planted with virus-free propagation stocks. No yield reductions were observed in a plot planted with SPFMV-infected cuttings. In plots infected with SPSVV alone, no significant effect on tuber yields was observed in one year, whereas in the second year there was aca 30% reduction in yield compared with virus-free control plants. Reinfection in the field, in the absence of introduced infection sources, was observed only with SPSVV. However, natural spread resulted when SPFMV-infected source plants were introduced. This implies that aphid vectors were present during the growing season, but that SPFMV infection sources were absent from the area.     

甘薯脱毒技术及增产效果研究

作者于１９８８～１９９５年研究了甘薯病毒及甘薯脱毒技术,明确了侵染山东甘薯的主要病毒种类是甘薯羽状斑驳病毒和甘薯潜隐病毒,在国内首次分离侵染甘薯的烟草花叶病毒,探明了其生物学特性。筛选出适合山东甘薯茎尖培养基的最佳激素配比,浓度,ｐＨ值。探索了脱毒薯的增产机理和增产效果,提出了组织培养,茎尖苗检测,脱毒薯速率与推广应用的配套技术规程,培养出徐薯１８等１２个品种的脱毒苗,平均增产４２．９％出干率提高     

中国甘薯病毒的血清学检测

 作者用4种甘薯病毒抗体(IgG),3种血清学方法(DAS-ELISA、Dot-blot-ELISA和ISEM)对北京,江苏、四川、山东四省(市)的253份甘薯病毒病样品进行了检测。结果表明:上述地区甘薯中普遍存在甘薯羽状斑驳病毒(SPFMV)和甘薯潜隐病毒(SPLV),尚难确定是否存在甘薯轻斑驳病毒(SPMMV)和甘薯花叶菜花叶状病毒(Sweet Potato Caulimo-like Virus,SPCLV)。21%的显症样品同上述4种病毒的抗血清不产生反应,显示我国甘薯上尚存在其它病毒。用Dot blot-ELISA和ISEM检测甘薯病毒比用DAS-ELISA灵敏准确。     

甘薯病毒病害SPVD抗性鉴定方法及产量损失估计

为了建立规范、有效的甘薯病毒病害（sweet potato virus disease,SPVD）抗性鉴定方法,于2011—2012连续两年,利用田间人工嫁接病毒接穗的方法对12个甘薯品种进行抗性鉴定和产量损失测定。结果显示,嫁接接种后,接穗成活率接近100%,12个品种都有不同程度发病,病情指数在51.0~95.2之间;感染SPVD的甘薯植株叶绿素含量降低、蔓长缩短;单株薯块产量损失范围在55.1%~97.8%之间。研究表明,供试的12个甘薯主栽品种感染SPVD后均可引起严重的产量损失,且田间人工嫁接病毒接穗是一个有效的SPVD抗性鉴定方法。     

The Helper Component-Proteinase of Sweet potato feathery mottle virus Facilitates Systemic Spread of Potato virus X in Ipomoea nil

ABSTRACT When Ipomoea nil was coinfected with Sweet potato feathery mottle virus (SPFMV), a member of the genus Potyvirus, and Potato virus X (PVX) typical symptoms caused by PVX were observed on those by SPFMV on the first upper true leaves at 14 days postinoculation (dpi). On the other hand, no PVX-induced symptoms were observed on the first upper true leaves at 14 dpi when plants were infected with PVX alone. In the case of coinfection with PVX and SPFMV, PVX RNA was detected not only in the inoculated cotyledonary leaves but also in the first upper true leaves at 14 dpi. In the case of single infection with PVX, PVX RNA was detected in the inoculated cotyledonary leaves but not in the first upper true leaves at 14 dpi. The accumulation of SPFMV remained unchanged, regardless of whether the inoculum consisted of SPFMV alone or a mixture of SPFMV and PVX. Although recombinant PVX engineered to express the helper component-proteinase (HC-Pro) of SPFMV (PVX.HC) enhanced symptoms severity in Nicotiana benthamiana, PVX.HC induced the synergism characterized by an enhanced viral movement in Ipomoea nil. Immunofluorescence microscopic examination revealed that the HC-Pro was present in phloem of SPFMV-infected I. nil. These results suggest that SPFMV HC-Pro acts as an enhancer of long distance movement for PVX in I. nil.