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.     

Identification and characterization of a mechanical transmissible begomovirus causing leaf curl on oriental melon

Oriental melon plants, Cucumis melo var. makuwa cv. Silver Light, showing virus-induced symptoms of mosaic, leaf curl and puckering were observed in the fields of eastern Taiwan in 2007. A virus culture, designated as SL-1, isolated from the diseased melon was established in systemic host plants, Nicotiana benthamiana and oriental melon, by mechanical inoculation. SL-1 did not react to the antisera against common cucurbit-infecting RNA viruses. Viral DNAs extracted from the diseased plant were amplified with the degenerate primers for begomoviruses. The full-length genomic DNA-A and DNA-B of SL-1 were sequenced and found to be closest, with 97.7% and 90.6% nucleotide identity, respectively, to Tomato leaf curl New Delhi begomovirus (ToLCNDV) cucumber isolate from a group of cucurbit-infecting begomoviruses. The virus SL-1 was designated as ToLCNDV oriental melon isolate (ToLCNDV-OM). The pathogenicity of ToLCNDV-OM was confirmed by agroinfection. Progeny virus from the agroinfected N. benthamiana plants was able to infect oriental melon by mechanical inoculation and caused symptoms similar to the original diseased melon in the field. The ToLCNDV-OM also infected five other species of cucurbitaceous plants by mechanical inoculation. This is the first report of a new ToLCNDV isolate causing severe disease on oriental melon in Taiwan.     

Variability of some plant species from different origins and their suitability for virus work

Plants of four species obtained from various sources were raised and compared for their suitability as test plants for a number of viruses. The species comprisedChenopodium amaranticolor (local lesion host of red clover mottle virus),Nicotiana glutinosa (local lesion host of tobacco mosaic virus (TMV)),N. rustica (systemic host of TMV, cucumber mosaic virus and tomato spotted wilt virus) andN. tabacum ‘White Burley’ (systemic host of TMV). Some sources proved to be more attractive as test plants or experimental hosts because of, e.g., production of more local lesions per unit of leaf area (C. amaranticolor andN. glutinosa), distinctness of lesions (C. amaranticolor), development of more pronounced systemic symptoms (N. rustica andN. tabacum ‘White Burley’), better growth characteristics (particularlyC. amaranticolor andN. rustica), smoother leaves being easier to rub (N. glutinosa) or more and bigger leaf formation (particularlyN. rustica). The implications for the interpretation of host range studies and the quest for propagation and assays hosts are discussed.     

Cucumber mosaic virus isolated from Yucca flaccida

Cucumber mosaic virus (CMV) was isolated fromYucca flaccida. The isolate was identified as CMV by host range, ways of transmission, physical properties and serology. No symptoms appeared on healthyYucca seedlings inoculated with purified virus or virus-containing sap, neither could the virus be recovered from these plants.     

Survey and characterization of potyviruses and their strains of Allium species

Nearly 5700 plants of 14 cultivated and 8 wildAllium species and varieties from the Netherlands and other parts of the world, were tested for infection with aphid-borne potyviruses by ELISA, electron microscope decoration tests and/or inoculation onto test plants. This resulted in the detection of two known viruses, viz. leek yellow stripe virus (LYSV) and onion yellow dwarf virus (OYDV), and the discovery and characterization of two new viruses, viz. shallot yellow stripe virus (SYSV) and Welsh onion yellow stripe virus (WoYSV), and of six strains of these viruses. ‘Garlic mosaic’, ‘barlic yellow streak’, ‘onion mosaic’, ‘shallot mosaic’, ‘shallot X’, and ‘shallot yellows’ viruses, incompletely described in the literature, are now reidentified as well-known viruses or as strains or mixtures of such viruses. ‘Garlic yellow stripe virus’ is also a complex containing a potyvirus possibly differing from the viruses found in this survey. The symptoms of the potyviruses studied varied widely and ranged from mild to severe chlorotic to yellow striping of leaves, and they are of little diagnostic importance.LYSV was found in vegetatively propagated pearl onion (A. ampeloprasum var.sectivum) from Europe and Asia. It has decreased in leek crops (A. ampeloprasum var.porrum) in the Netherlands since the 1970, apparently due to resistance in new cultivars. OYDV was common in onion (A. cepa var.cepa) from the former USSR and North Africa, and in European cultivars of shallot (A. cepa var.ascalonicum), with the exception of the highly resistant ‘Santé’, but was not detected during this survey in Asian shallot. European samples of ever-ready onion (A. cepa var.perutile), multiplier onion (A. cepa var.aggregatum) and tree onion (A. cepa var.viviparum) contained OYDV. It was also found in sand leek (A. scorodoprasum) from european gene collections. A strain of OYDV from onion and shallot in Morocco and Spain was virulent on onion and shallot cultivars resistant to common OYDV, as reported early for a similar isolate in the USA.Asian shallot appeared generally infected with the new SYSV, similar to OYDV in host range and symptoms but serologically distinct. It was not detected in onion and shallot from Europe or North Africa. A virulent strain of this virus caused striping in sap-inoculated garlic (A. sativum) and Formosan lily (Lilium formosanum). The new WoYSV, infecting Welsh onion in Indonesia and Japan, was earlier described in Japan as OYDV from rakkyo and Welsh onion. It appeared serologically closely related to SYSV and distantly to OYDV, but differed in its host range.Host-specific strains of LYSV and OYDV were detected in garlic, wild garlic (A. longicuspis), an unidentifiedAllium species (suffix-G), and great-headed garlic (A. ampeloprasum var.holmense) (suffix-GhG)., LYSV-G and OYDV-G infected on average 45% and 73%, respectively, of the garlic samples of worldwide origin. Symptoms of isolates of both strains varied in severity, implying the necessity of serological tests for disease diagnosis and health certification. LYSV-GhG was the cause of yellow striping in 93% of the great-headed garlic plants tested, mainly from the Mediterranean area. One sample was also infected with OYDV-GhG.Many samples from vegetatively propagated crops grown from non-certified planting stock contained a few plants free of potyviruses, implying the possibility to obtain healthy (and possibly resistant) selections of such cultivars avoiding meristem-tip culture. Cross-protection of garlic sets by a mild potyvirus isolate seems to be an alternative to the use of vulnerable virus-free sets.Generally, viruses and virus strains could not be transmitted to anyAllium species other than their natural host, except to the highly susceptible crow garlic (A. vineale). This species, and other predominantly vegetatively propagating wildAllium spp. (field garlic,A. oleraceum; ramsons,A. ursinum; sand leek), were found not to be reservoirs of viruses that might infectAllium crops in the netherlands. Streaking in vegetatively propagated wild leeks (A. ampeloprasum and closely related species) originating from the Mediterranean area and Asia was due to an undescribed miteborne virus. The survey confirmed that spread of potyviruses inAllium crops in the Netherlands is from planting sets, and from a neighbouring crop only if of the same species.     

Systemic infection of some N-gene-carrying Nicotiana species and cultivars after inoculation with tobacco mosaic virus

Since July 1974Nicotiana tabacum ‘Samsun NN’ plants, inoculated with the common strain of tobacco mosaic virus (TMV), have occasionally been found to develop necrosis on non-inoculated upper leaves 2–7 days after the local necrotic lesions had appeared on the lower leaves. All these plants had been kept in a growth chamber at 17–20°C. Other tobacco species and cultivars carrying theN gene, such asN. glutinosa andN. tabacum ‘Xanthi-nc’, showed the same phenomenon. Substantial amounts of TMV could be recovered from leaves with systemic symptoms. The systemic necrosis somewhat resembled that caused by tobacco rattle virus (TRV). A number of possible causes, such as high concentration of the inoculum, contamination with another strain of TMV or with TRV, change in the genetic composition of the host plants and certain growing conditions (soil, water, pesticides) were investigated. None of these factors could be held fully responsible for the abnormal systemic reaction, although there was evidence that the soil could sometimes play an important rôle.     

Spread and control of Cucumber Mosaic Virus in gladiolus

Cucumber mosaic virus (CMV) and bean yellow mosaic virus are the most prevalent viruses in gladiolus fields in Israel. Factors affecting infection were studied, as a basis for the buildup of virus-tested propagation material. Marked differences in the susceptibility of gladiolus cultivars to aphid-borne infection were observed, both in field experiments and in test aphid inoculations. Cultivars ‘Euro-vision’ and ‘Trader Horn’ were resistant, while ‘Peter Pears’ and ‘Commando’ were highly susceptible. The aphid that landed most frequently on gladiolus wasMacrosiphum euphorbiae. In test inoculationsM. euphorbiae andAphis gossypii efficiently transmitted CMV from gladiolus to gladiolus, but did not transmit CMV from four other source plants. In field experiments, only those gladioli planted close to infected gladiolus sources became infected. Oil sprays in combination with coarse nets controlled CMV infection in the field efficiently.     

First occurrence of <Emphasis Type="Italic">Sugarcane streak mosaic virus</Emphasis> infecting sugarcane in Indonesia

On plants at 59 sugarcane plantations in Central and East Java, Indonesia, we found virus-like symptoms such as streak mosaic. The virus was transmitted mechanically and was sett-borne. The nucleotide sequence of the coat protein gene had the highest identity with that of Sugarcane streak mosaic virus (SCSMV) isolate Pakistani. We tentatively designate this isolate as SCSMV-Idn (Indonesia).     

Production of discernible disease phenotypes in Canna by five plant viruses belonging to the genera Potyvirus,Cucumovirus and Badnavirus

Cannas are tropical and subtropical flowering perennial plants. The genus contains many species but most commercially grown cultivars are interspecific hybrids selected for their attractive foliage and flowers. Canna production is so lucrative that there are farmers and nurseries dedicated solely to its production. The specific issue that the canna industry faces is virus diseases. In this study, rhizomes of 24 canna cultivars were gathered and diagnostics conducted to detect Bean yellow mosaic virus (BYMV, Potyvirus), Canna yellow mottle virus (CaYMV, Badnavirus), Canna yellow streak virus (CaYSV, Potyvirus), Cucumber mosaic virus (CMV, Cucumovirus) and Tomato aspermy virus (TAV, Cucumovirus). Visual assessment of disease symptoms and diagnostic tests were carried out to identify the prevalent diseases and describe the symptoms that are associated with virus infection. BYMV, CaYMV and CaYSV caused severe mosaic and necrosis either in the leaf lamina or veins of infected leaves. Potyvirus infection suppressed red colouration in the foliage of some varieties. CaYMV and CaYSV often appeared in the same plant, suggesting they might represent a viral complex. CMV and TAV were rarely seen in these populations. Interestingly, CaYMV but not CaYSV could be mechanically inoculated to Phaseolus vulgaris plants.     

侵染番红花的芜菁花叶病毒

 从表现花叶症状的德国进口番红花上获得一线状病毒分离物SA,线状病毒粒子长度为700~800nm。其在人工接种的11科39种植物中能侵染6科14种植物,在克里芙兰烟上产生系统坏死,在小白菜、花椰菜等十字花科植物上产生系统花叶或为隐症,在昆诺藜等藜科植物上为局部侵染。在番红花病叶、球茎及克里芙兰烟病叶组织中观察到卷轴状和片层状聚集的风轮状内含体。免疫吸附和免疫修饰电镜观察结果显示,SA与芜菁花叶病毒((TuMV)具有紧密的血清学关系。根据这些特征将SA鉴定为TuMV的一个分离物。这是TuMV侵染番红花的首次报道。     

Molecular characterization of Citrus yellow mosaic badnavirus (CMBV) isolates revealed the presence of two distinct strains infecting citrus in India

Citrus yellow mosaic badnavirus (CMBV) is a non-enveloped, bacilliform DNA virus and the etiologic agent of yellow mosaic disease of citrus in India. The disease was initially reported from the southern parts of India and has now spread to other parts of the country. It is a serious disease of sweet orange (Citrus sinensis) in southern India, where it causes significant yield losses. During a recent survey of citrus groves in the Nagpur region, central India, characteristic mosaic symptoms were observed in mandarin orange (Citrus reticulata) and sweet orange. Virus transmission studies, electron microscopy, PCR amplification and sequencing of cloned PCR products from samples showing mosaic symptoms confirmed the presence of a badnavirus. The CMBV–Nagpur isolate could be transmitted to the Rangpur lime (C. limonia) and acid lime (Citrus aurantifolia) by graft inoculation. Sequence analysis of a segment of ORF-III region and intergenic region (IR) of the viral genome revealed that CMBV–Nagpur isolate formed a distinct clade along with some previously reported isolates that are known to infect acid lime and Rangpur lime. CMBV isolates that infect citrus species other than the acid lime and Rangpur lime formed a second clade. Based on the transmission studies and phylogenetic analyses, it was concluded that at least two strains of CMBV exist in India currently.     

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%。     

Genetic diversity and mixed infections of begomoviruses infecting tomato, pepper and cucurbit crops in Nicaragua

Begomoviruses were detected in Nicaraguan fields of tomato ( Lycopersicon esculentum ) and adjacently growing plants of pepper ( Capsicum annuum ), chilli pepper ( C . baccatum ), cushaw ( Cucurbita argyrosperma ) and Mexican fireplant ( Euphorbia heterophylla ) using polymerase chain reaction (PCR) and universal begomovirus primers. All tomato and Mexican fireplant plants showing symptoms were infected with begomoviruses, while only 30–46% of the pepper, chilli pepper and cushaw plants showing symptoms tested virus-positive. No begomoviruses were found in potato. The virus species were provisionally identified by sequencing 533 bp of the viral coat protein gene ( AV1 ). Tomato severe leaf curl virus (ToSLCV), Tomato leaf curl Sinaloa virus (ToLCSinV) and Pepper golden mosaic virus (PepGMV) were found to infect both tomato and pepper. A new provisional species designated Tomato leaf curl Las Playitas virus (ToLCLPV) was detected in a tomato plant. Squash yellow mottle virus (SYMoV) and PepGMV were found in cucurbits, the latter for the first time in this host. Euphorbia mosaic virus (EuMV) was detected in Mexican fireplant. Sequencing of a larger number of PCR-amplified clones from selected plants revealed intraspecific viral sequence variability, and also multiple begomovirus infections which could represent up to three species in a single tomato or cushaw plant. Phylogenetic grouping of virus sequences did not correlate with the host of origin.     

‘Candidatus Phytoplasma ziziphi’ associated with Sophora japonica witches’ broom disease in China

Chinese scholar tree (Sophora japonica) with witches’ broom symptoms was observed in Shandong Province in China. Phytoplasmas were detected in the diseased plants using 16S rDNA amplification with phytoplasma-specific universal primer pairs. On the basis of the results of 16S rDNA sequencing, virtual restriction fragment length polymorphism patterns and phylogenetic analyses, the phytoplasma found in S. japonica with witches’ broom symptoms was confirmed as a ‘Candidatus Phytoplasma ziziphi’-related strain belonging to the Elm yellows group 16SrV. This is the first report of ‘Ca. P. ziziphi’ infecting S. japonica plant with witches’ broom symptoms.     

Apple necrotic mosaic virus,a novel ilarvirus from mosaic-diseased apple trees in Japan and China

The causal agent of apple mosaic disease has been previously thought to be solely caused by apple mosaic virus (ApMV). In this study, we report that a novel ilarvirus is also associated with apple mosaic disease. Next-generation sequencing analysis of an apple tree showing mosaic symptoms revealed that the tree was infected with three apple latent viruses (apple stem pitting virus, apple stem grooving virus, and apple chlorotic leaf spot virus) and a novel ilarvirus (given the name apple necrotic mosaic virus (ApNMV)) that is closely related to Prunus necrotic ringspot virus (PNRSV) and ApMV. The genome of ApNMV consists of RNA1 (3378 nt), RNA2 (2767 nt), and RNA3 (1956 nt). A phylogenetic analysis based on the coat protein amino acid sequences indicated that the novel virus belongs to the same subgroup 3 of the genus Ilarvirus as PNRSV and ApMV. The presence of mosaic leaves, which tend to be unevenly distributed in diseased apple trees, was correlated with the internal distribution of ApNMV. RT-PCR detection of mosaic-diseased apple trees in Japan indicated that ApNMV was detected in apple trees introduced from China, whereas ApMV was detected from cultivated apple trees in domestic orchards. Consistent with these findings, a survey of mosaic-diseased apple trees in major apple-producing provinces in China revealed that the majority of apple trees showing mosaic symptoms in China are infected with ApNMV.     

The occurrence of three viruses in hop (Humulus lupulus) in China

Forty-two percent of leaf samples taken from hop cv. Qingdao Dahua growing in plantations in northeastern China in 1983-1984 were infected with hop mosaic virus (HMV) and/or hop latent virus (HLV). Mosaic or line-pattern symptoms were seen in some plants but only in spring and it is uncertain if the symptoms were caused by either virus which appeared in our studies to be similar, both serologically and in host range, to HMV and HLV described in Europe and North America. In host range studies, HMV infected Nicotiana clevelandii systemically without inducing symptoms. Occasionally it caused chlorotic spots in the inoculated leaves of Chenopodium quinoa and brown star-point lesions in inoculated leaves of Phaseolus vulgaris cv. Topcrop, The virus was purified by PEG precipitation from extracts of N. clevelandii plants; yields were about 40-120 mg/kg fresh leaves. The virus contained a single protein (estimated molecular weight 34 200) that was estimated to contain 272 amino acids with no methionine, and a single RNA species (estimated molecular weight 295 x 10⁶) that represented c. 6% of the particle weight. HLV sometimes caused inconspicuous chlorotic spots in inoculated leaves of C. murale and local pinpoint lesions in P. vulgaris in winter only. A virus similar to alfalfa mosaic virus was isolated from leaves of hop cv. Golding and caused systemic necrotic symptoms in C. quinoa and C. amaranticolor , and systemic chlorotic spots in hop cv. Styrian.     

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.