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1.
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2.
Actinidia chinensis and A. deliciosa plants from China, showing a range of symptoms, including vein clearing, interveinal mottling, mosaics and chlorotic ring spots, were found to contain ~300 nm rod-shaped virus particles. The virus was mechanically transmitted to several herbaceous indicators causing systemic infections in Nicotiana benthamiana, N. clevelandii, and N. occidentalis, and local lesions in Chenopodium quinoa. Systemically- infected leaves reacted with a Tobacco mosaic virus polyclonal antibody in indirect ELISA. PCR using generic and specific Tobamovirus primers produced a 1,526 bp sequence spanning the coat protein (CP), movement protein (MP), and partial RNA replicase genes which showed a maximum nucleotide identity (88%) with Turnip vein clearing virus and Penstemon ringspot virus. However, when the CP sequence alone was considered the highest CP sequence identity (96% nt and 98% aa) was to Ribgrass mosaic virus strain Kons 1105. The morphological, transmission, serological and molecular properties indicate that the virus is a member of subgroup 3 of the genus Tobamovirus.  相似文献   

3.
We demonstrated that only 2 out of 15 isolates of Tobacco leaf curl Yunnan virus (TbLCYNV) were associated with the satellite DNAβ molecules. To investigate the infectivity of this virus, an infectious clone of TbLCYNV isolate Y143 (TbLCYNV-Y143) was agroinoculated or whitefly transmitted into Nicotiana benthamiana, N. glutinasa, Petunia hybrida and N. tabacum. TbLCYNV-Y143 alone was able to induce severe upward leaf curling, vein thickening or stunt symptoms in these plants. Co-inoculation of TbLCYNV-Y143 with DNAβ molecules associated with other begomoviruses induced similar symptom types on these plants. This indicates that TbLCYNV is a monopartite begomovirus. The relevance of results that only two isolates of TbLCYNV were associated with DNAβ molecules is discussed.  相似文献   

4.
Sequential transmission tests of Peanut stunt virus (PSV) and Cucumber mosaic virus (CMV) systemically infecting common bean, Phaseolus vulgaris, were conducted using Myzus persicae allowed to fast for 2 hr and then to acquisition feed on infected common bean plants or purified virus for 10 min. In the sequential transmission tests using either one or 10 aphids per assay plant, three isolates of PSV (J,S,Y5) and one of CMV (V) were transmitted from and to common bean up to a third or fourth inoculation access. Many aphids transmitted these viruses to two or three plants. Purified viruses of PSV-S and CMV-V were also transmitted up to a third or second inoculation access at low percentage. On tobacco, Nicotiana tabacum, aphids transmitted PSV-S and CMV-V only in the first inoculation access, although PSV-S was transmitted to only one plant in the fourth and fifth inoculation access. These viruses may be transmitted in two phases by aphids, depending on the plant species. Received 16 April 1999/ Accepted in revised form 1 September 1999  相似文献   

5.
为明确黄瓜花叶病毒（cucumber mosaic virus,CMV）甜瓜分离物的分子变异情况及其侵染性,对2个甜瓜分离物CH99和XH18的基因组进行克隆、测序和分析,并通过构建全长cDNA克隆分析其侵染性。结果显示,黄瓜花叶病毒甜瓜CH99分离物3条RNA长度分别为3 356、3 049和2 211 nt,甜瓜XH18分离物3条RNA长度分别为3 381、3 048和2 217 nt。分离物CH99与XH18的核苷酸序列一致性为89.40%～95.80%,氨基酸序列一致性为90.00%～97.80%,CH99分离物与其他CMV分离物的核苷酸和氨基酸序列一致性平均值分别为79.23%～89.29%和73.52%～93.90%,XH18分离物与其他CMV分离物的核苷酸和氨基酸序列一致性平均值分别为79.81%～89.83%和74.02%～95.14%。遗传发育分析显示,这2个分离物均属于亚组IB成员。接种试验结果显示,分离物CH99和XH18的侵染性克隆构建成功,这2个分离物均能系统侵染本生烟、甜瓜和黄瓜,并在本生烟和甜瓜上引起较严重的症状,在黄瓜上引起的症状较弱,而二者均不能侵染西...  相似文献   

6.
A putative virus-induced disease showing chlorotic spots on leaves of Phalaenopsis orchids was observed in central Taiwan. A virus culture, phalaenopsis isolate 7-2, was isolated from a diseased Phalaenopsis orchid and established in Chenopodium quinoa and Nicotiana benthamiana. The virus reacted with the monoclonal antibody (POTY) against the potyvirus group. Potyvirus-like long flexuous filament particles around 12–15 × 750–800 nm were observed in the crude sap and purified virus preparations, and pinwheel inclusion bodies were observed in the infected cells. The conserved region of the viral RNA was amplified using the degenerate primers for the potyviruses and sequence analysis of the virus isolate 7-2 showed 56.6–63.1% nucleotide and 44.8–65.1% amino acid identities with those of Bean yellow mosaic virus (BYMV), Beet mosaic virus (BtMV), Turnip mosaic virus (TuMV) and Bean common mosaic virus (BCMV). The coat protein (CP) gene of isolate 7-2 was amplified, sequenced and found to have 280 amino acids. A homology search in GenBank indicated that the virus is a potyvirus but no highly homologous sequence was found. The virus was designated as Phalaenopsis chlorotic spot virus (PhCSV) in early 2006. Subsequently, a potyvirus, named Basella rugose mosaic virus isolated from malabar spinach was reported in December 2006. It was found to share 96.8% amino acid identity with the CP of PhCSV. Back-inoculation with the isolated virus was conducted to confirm that PhCSV is the causal agent of chlorotic spot disease of Phalaenopsis orchids in Taiwan. This is the first report of a potyvirus causing a disease on Phalaenopsis orchids.  相似文献   

7.
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.  相似文献   

8.
Endoplasmic reticulum (ER) stress may induce two cell defence pathways, the unfolded protein response (UPR) or programmed cell death (PCD) upon unmitigated stress. This study confirmed that viral infection could induce ER stress through changing ER morphology and up‐regulating ER stress‐related genes, including NbNAC089. AtNAC089 serves as an ER stress sensor to regulate PCD in Arabidopsis. In this study, Nicotiana benthamiana NbNAC089 was identified. The gene encoded a 409 amino acid protein with a putative transmembrane domain near the C‐terminus and a NAC domain at the N‐terminus. NbNAC089 was localized to the ER membranes, and a truncated form of NbNAC089, lacking the transmembrane domain, was localized to the nucleus. Meanwhile, the full length of NbNAC089 was activated and cleaved in response to viral infection. The results suggest that the native protein may be translocated to the nucleus by release from the membrane during viral infection. Knock‐down of NbNAC089 in N. benthamiana increased susceptibility to Tobacco mosaic virus or Cucumber mosaic virus, and, in addition, promoted up‐regulation of UPR genes but impaired up‐regulation of PCD genes. These results show that NbNAC089 is a negative regulator of UPR and a positive regulator of PCD, and plays a role in the process of viral infection.  相似文献   

9.
A viral isolate from Egypt associated with symptoms of enations and leaf curling on hollyhock (Althea rosea) was characterized at the cytopathological and molecular levels. Microscopic observations showed that enations resulted from a reorganization of the vascular tissues, including activation of a cambial activity in the phloem, the development of a palisade parenchyma in place of a spongy one and the differentiation of minor vascular tissues. From this isolate, the full-length DNA-A of a begomovirus (family Geminiviridae) was cloned and sequenced. This genome exhibited a genetic organization similar to that of other old-world begomoviruses like Tomato yellow leaf curl virus from Israel and Ageratum yellow vein virus from Singapore. However, its sequence was significantly distinct (similarity < 69%) from any other geminivirus. This begomovirus was thus considered as representative of a new viral species named Althea rosea enation virus (AREV). AREV was agroinfectious on Nicotiana benthamiana, on which it induced a severe leaf-curling and vein distortion, but could not re-establish infection on A. rosea. To determine if AREV was also associated with a similar disease affecting okra in Upper-Egypt, the partial sequence of the coat protein gene of an isolate was determined. It exhibited 90% nt identity with the hollyhock isolate (97% amino acid), suggesting a genetic heterogeneity in the begomovirus population associated with the enation diseases.  相似文献   

10.
Potato mop‐top virus (PMTV) causes necrotic flecks inside and on tubers in temperate countries. In South America, these symptoms have not been observed, although the presence of the virus has been confirmed in the Andes and in Central America. To characterize PMTV isolates from the Andes, soil samples were taken from the main potato‐producing regions in Colombia and virus was recovered by planting Nicotiana benthamiana as bait plants. The complete genomes of five isolates were sequenced and three of the isolates were inoculated to four different indicator plants. Based on sequence comparisons, three types of RNA‐CP (RNA2) and RNA‐TGB (RNA3) were found. The isolates from the centre of the country (CO3 and CO4) were similar to isolates from Europe. The genomes of CO1, CO2 and CO5 differ from other PMTV isolates, placing them in a separate clade in phylogenetic trees. The three Colombian isolates (CO1, CO2 and CO5) only induced slightly different symptoms in the indicator plants. However, the isolate from the northwest of the country (CO1) induced stronger symptoms in N. benthamiana including severe stunting. A correlation between the genotype of the isolates and the symptoms they induced on indicator plants was not found.  相似文献   

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13.
Between 1998 and 2009, the four tomato‐infecting begomovirus species detected in Taiwan were Ageratum yellow vein Hualien virus (AYVHuV), Tomato leaf curl Taiwan virus (ToLCTWV), Tomato yellow leaf curl Thailand virus (TYLCTHV) and a newly defined species Tomato leaf curl Hsinchu virus (ToLCHsV). AYVHuV was detected occasionally in 2003 and ToLCHsV only in 2000–2001, whilst ToLCTWV was detected throughout the period. TYLCTHV was first detected in 2005. Between 1998 and 2005, >99% of the begomovirus‐positive samples were infected with ToLCTWV. In 2007 in western Taiwan, 16% of the positive samples were infected with ToLCTWV, 35% with TYLCTHV and 49% with mixed infection (ToLCTWV/TYLCTHV). In contrast, in eastern Taiwan the proportions were 84% ToLCTWV, 2% TYLCTHV and 14% mixed infection. However, throughout Taiwan in 2008–2009, most positive samples were either identified as TYLCTHV (51%) or mixed infection (ToLCTWV/TYLCTHV; 41%), and only 8% were ToLCTWV. This shows a clear trend of shifting from ToLCTWV to TYLCTHV and mixed infection over a short time period in Taiwan. Sequence analyses indicated that tomato‐infecting AYVHuV, an apparent recombinant between ToLCTWV and AYVHuV from Ageratum, represents a new strain Hsinchu. TYLCTHV Taiwan isolates were highly similar to each other, whereas ToLCTWV isolates had greater diversity and were classified into three strains which had one country‐wide and two local distributions. ToLCTWV and TYLCTHV were confirmed as monopartite and bipartite begomoviruses, respectively, by agroinfection followed by transmission with Bemisia tabaci biotype B. In addition, TYLCTHV was found to be mechanically transmissible together with viral DNA‐B.  相似文献   

14.
A putative virus-induced disease showing chlorotic ringspots on leaves of Phalaenopsis orchids has been observed in Taiwan for several years. A virus culture, 91-orchid-1, isolated from a Phalaenopsis orchid bearing chlorotic ringspot symptoms was established in Chenopodium quinoa and Nicotiana benthamiana, and characterized serologically and biologically. The virus reacted slightly with the antiserum of Watermelon silver mottle virus (WSMoV) but not with those of Tomato spotted wilt virus (TSWV), Impatiens necrotic spot virus (INSV) and Groundnut ringspot virus (GRSV). Isometric particles measuring about 70–100 nm were observed. Inoculation with isolated virus was conducted to confirm that 91-orchid-1 is the causal agent of chlorotic ringspot disease of Phalaenopsis orchids. To determine the taxonomic relationships of the virus, the conserved region of L RNA and the complete nucleocapsid gene (N gene) were cloned and sequenced. The sequence of conserved region of L RNA shares 83.8, 82.5, 64.4 and 64.9% nucleotide identities and 96.5, 97.7, 67.3 and 67.6% amino acid identities with those of Peanut bud necrosis virus (PBNV), WSMoV, TSWV and INSV, respectively, indicating that 91-orchid-1 is a tospovirus related to WSMoV. The complete nucleotide sequence of the N gene determined from a cDNA clone was found to be 828 nucleotides long encoding 275 amino acids. Sequence analyses of the N gene showed that 91-orchid-1 is an isolate of Capsicum chlorosis virus (CaCV) which has been reported to infect tomato and capsicum plants in Australia and Thailand. 91-orchid-1 is therefore designated as CaCV-Ph. To our knowledge, this is the first formal report of a tospovirus infecting Phalaenopsis orchids.  相似文献   

15.
Tomato yellow leaf curl disease is one of the most devastating viral diseases affecting tomato crops worldwide. This disease is caused by several begomoviruses (genus Begomovirus, family Geminiviridae), such as Tomato yellow leaf curl virus (TYLCV), that are transmitted in nature by the whitefly vector Bemisia tabaci. An efficient control of this vector‐transmitted disease requires a thorough knowledge of the plant–virus–vector triple interaction. The possibility of using Arabidopsis thaliana as an experimental host would provide the opportunity to use a wide variety of genetic resources and tools to understand interactions that are not feasible in agronomically important hosts. In this study, it is demonstrated that isolates of two strains (Israel, IL and Mild, Mld) of TYLCV can replicate and systemically infect A. thaliana ecotype Columbia plants either by Agrobacterium tumefaciens‐mediated inoculation or through the natural vector Bemisia tabaci. The virus can also be acquired from A. thaliana‐infected plants by B. tabaci and transmitted to either A. thaliana or tomato plants. Therefore, A. thaliana is a suitable host for TYLCV–insect vector–plant host interaction studies. Interestingly, an isolate of the Spain (ES) strain of a related begomovirus, Tomato yellow leaf curl Sardinia virus (TYLCSV‐ES), is unable to infect this ecotype of A. thaliana efficiently. Using infectious chimeric viral clones between TYLCV‐Mld and TYLCSV‐ES, candidate viral factors involved in an efficient infection of A. thaliana were identified.  相似文献   

16.
Abstract In the frame of the investigation of epidemiology of soil-borne viruses, like the Soil-borne cereal mosaic virus (SBCMV), Soil-borne wheat mosaic virus (SBWMV) and the Bymovirus Wheat spindle streak mosaic virus (WSSMV), which were transmitted by fungal vector Polymyxa graminis Ledingham, the infection progress in different cereals was observed. The detection of furovirus and bymovirus in field plants was depending on temperature conditions during the vegetation period and the kind of cereals. The furoviruses tolerate a broad temperature spectrum and once established infection is detectable until the harvest time. In contrast to this observation, the propagation of WSSMV seems to be restricted to lower temperatures. Consequently, this virus is detected best at the end of February until the middle of April. Among the tested cereals, rye becomes more early infected than wheat and triticale. Both furoviruses could be differed by variable virulence reactions on cereal hosts and indicator plants. The SBCMV infects rye, triticale and wheat but not barley. The SBWMV is able to contaminate beside these cultures barley too. Both viruses are distinguished in the infection typ in Nicotiana benthamiana. Whereas SBCMV isolates spread out in the whole plant and cause yellowing and the die back of plants, the SBWMV infects the inoculated leaves only.  相似文献   

17.
The geographic incidence, genetic diversity and phylogenetic relationships of Melon necrotic spot virus (MNSV) and Olpidium isolates were studied in three cucurbit species from several Latin American and European countries on different collecting dates. Of the 112 cucurbit samples analysed, 69 from Guatemala, Honduras, Mexico, Panama and Spain were DAS‐ELISA‐positive for MNSV. Olpidium bornovanus and O. virulentus infections, and MNSV infections mixed with these Olpidium species, were observed for all these countries. Twenty‐nine MNSV isolates from all the origins where the virus was detected were selected and amplified by RT‐PCR. The resulting RT‐PCR of the p29, p89, p7A, p7B and p42 proteins was used to estimate the genetic diversity and the phylogenetic relationships of the MNSV population. The sequences obtained in this study were compared with the MNSV sequences of the NCBI database, and three groups were recovered by nucleotide composition according to geographical origins: the EU‐LA genotype group (with two subgroups: EU and LA, European and Latin American isolates, respectively), the JP melon genotype group (Japanese melon reference isolates) and the JP watermelon genotype group (Japanese watermelon reference isolates). The genetic diversity in the entire p7A and p7B proteins of MNSV suggests that these coding regions are under strong selective pressure. Additionally, the rDNA‐ITS region was analysed in 40 O. bornovanus and O. virulentus isolates associated with each geographical location and host examined. Phylogenetic analysis showed two groups for each Olpidium species, and these groupings were related to the host from which they were originally isolated.  相似文献   

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20.
Pumpkin yellow vein mosaic disease (PYVMD) causes significant damage to pumpkin production throughout India. A begomovirus causing PYVMD in South India was characterized recently but the nature of virus causing the disease in North India was not known. Samples of PYVMD were obtained from North India and two putative begomoviruses were PCR‐amplified and sequenced. Comparison of complete DNA‐A sequences indicated that PYVMD in North and South India were caused by two distinct begomoviruses and shared only approximately 88% DNA‐A nucleotide identity. The South Indian isolate was most closely related to Squash leaf curl China virus between 91 and 96% identities, and the two North Indian isolates to Tomato leaf curl New Delhi virus between 94 and 96% identities. The South Indian isolate was previously shown to be transmitted by the indigenous biotype of Bemisia tabaci, however, the situation has since changed with the introduction of the B‐biotype to South India in 1999. Comparative transmission experiments between the indigenous biotype v/s the introduced B‐biotype for the time required for virus acquisition (30 min v/s 15 min), inoculation (15 min v/s 10 min) and incubation (30 min v/s 4 h) have indicated that the B‐biotype transmits the virus quickly and more efficiently than the indigenous biotype. An epidemic of PYVMD was recorded for the first time in South India in 2004 with disease incidences of up to 100% and significant yield losses. This may be due to a combination of several factors including the large numbers of B‐biotype populations, the ability of the B‐biotype to transmit the virus efficiently and the cultivation of susceptible varieties. These possibilities and the threat to pumpkin cultivation associated with the spread of the B‐biotype in India are discussed.  相似文献   

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