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1.
Mirafiori lettuce big-vein virus (MLBVV) and Lettuce big-vein associated virus (LBVaV) are found in association with big-vein disease of lettuce. Discrimination between the two viruses is critical for elucidating the etiology of big-vein disease. Using specific antibodies to MLBVV and LBVaV for western blotting and exploiting differences between MLBVV and LBVaV in host reaction of cucumber and temperature dependence in lettuce, we separated the two viruses by transfering each virus from doubly infected lettuce plants to cucumber or lettuce plants. A virus-free fungal isolate was allowed to acquire the two viruses individually or together. To confirm the separation, zoospores from MLBVV-, LBVaV-, and dually infected lettuce plants were used for serial inoculations of lettuce seedlings 12 successive times. Lettuce seedlings were infected at each transfer either with MLBVV alone, LBVaV alone, or both viruses together, depending on the virus carried by the vector. Lettuce seedlings infected with MLBVV alone developed the big-vein symptoms, while those infected with LBVaV alone developed no symptoms. In field surveys, MLBVV was consistently detected in lettuce plants from big-vein-affected fields, whereas LBVaV was detected in lettuce plants not only from big-vein-affected fields but also from big-vein-free fields. LBVaV occurred widely at high rates in winter-spring lettuce-growing regions irrespective of the presence of MLBVV and, hence, of the presence of the big-vein disease.  相似文献   

2.
One of the economically important diseases of lettuce is lettuce big-vein disease (LBVD), which leads to severe yield losses. LBVD is associated with a complex of two viruses, Lettuce big-vein associated virus (LBVaV) and Mirafiori lettuce big-vein virus (MLBVV). These viruses are transmitted by motile zoospores of Olpidium spp. fungi, which persist in the soil for decades through resting spores. In greenhouse and field experiments, this study tested whether changing plant and soil temperatures together with fungicide application would have a significant effect on controlling LBVD in lettuce. Soil fumigation with metam sodium was not effective at controlling the disease, as opposed to treatment with chloropicrin and methyl bromide. Moreover, the fungicides carbendazim and fluazinam were effective in reducing the incidence of Olpidium virulentus. Nevertheless, control of the fungal vector did not seem to be sufficient to control the disease due to the transition ability of the virus under low vector abundance. Crop covers, which affect the favourable environmental conditions for the viruses by lowering soil temperature and raising air temperature, reduced the disease symptoms. Combining fungicides with crop cover had a synergistic effect on reducing disease symptoms, thus providing a sustainable solution for LBVD.  相似文献   

3.
Eight provinces of Iran were surveyed during 2003–2008 to find Brassicaceae reservoir weed hosts of Turnip mosaic virus (TuMV). A total of 532 weed samples were collected from plants with virus-like symptoms. The samples were tested for the presence of TuMV by enzyme-linked immunosorbent assay using specific antibodies. Among those tested, 340 samples (64%) were found to be infected with TuMV. Rapistrum rugosum, Sisymberium loeselii, S. irio and Hirschfeldia incana were identified as the Brassicaceae weed hosts of TuMV, and the former two plant species were found to be the most important weed hosts for the virus in Iran. The full-length sequences of the genomic RNAs of IRN TRa6 and IRN SS5 isolates from R. rugosum and S. loeselii were determined. No evidence of recombination was found in both isolates using different recombination-detecting programmes. Phylogenetic analyses of the weed isolates with representative isolates from the world showed that the IRN TRa6 and IRN SS5 isolates fell into an ancestral basal-Brassica group. This study shows for the first time the wide distribution and phylogenetic relationships of TuMV from weeds in the mid-Eurasia of Iran.  相似文献   

4.
Barley yellow dwarf disease is one of the most important problems confronting cereal production in Iran. Barley yellow dwarf virus-PAV (BYDV-PAV) and Cereal yellow dwarf virus-RPV (CYDV-RPV) are the predominant viruses associated with the disease. One isolate of BYDV-PAV from wheat (PAV-IR) and one isolate of CYDV-RPV from barley (RPV-IR) were selected for molecular characterisations. A genome segment of each isolate was amplified by PCR. The PAV-IR fragment (1264 nt) covered a region containing partial genes for coat protein (CP), read through protein (RTP) and movement protein (MP). PAV-IR showed a high sequence identity to PAV isolates from USA, France and Japan (96–97%). In a phylogenetic analysis it was placed into PAV group I together with PAV isolates from barley and oats. The fragment of RPV-IR (719 nt) contained partial genes for CP, RTP and MP. The sequence information confirmed its identity as CYDV. However, RPV-IR showed 90–91% identity with both RPV and Cereal yellow dwarf virus-RPS (CYDV-RPS). Phylogenetic analyses suggested that it was more closely related to RPS. These data comprise the first attempt to characterise BYD-causing viruses in Iran and southwest Asia. The nucleotide sequence data reported appear in the EMBL, GenBank and DDBJ Nucleotide Sequence Databases under the accession numbers AY450425 and AY450454  相似文献   

5.
Lettuce big-vein disease, caused by Mirafiori lettuce big-vein virus and Lettuce big-vein associated virus, is suppressed when the pH of field soil becomes acidic. Therefore, we evaluated the effect of soil pH on the activities of Olpidium virulentus, the vector of the viruses. We found that acidic soil, pH less than 6.0, significantly reduced O. virulentus infection of the root and influenced the detection rate of zoospores released in the surrounding water. We concluded that acidic soil suppresses zoospore release from zoosporangia.  相似文献   

6.
Geraniums (Pelargonium spp.) are traditional ornamental plants largely cultivated in Europe and northern America. Vegetative propagation makes them prone to viral infections, which have detrimental effects on crop production and quality. Asymptomatic samples collected in Spain were tested for a range of viruses using ELISA. The tobamovirus, Tobacco mosaic virus (TMV), the cucumovirus, Cucumber mosaic virus (CMV), and several viruses in the family Tombusviridae, namely, Pelargonium line pattern virus (PLPV), Pelargonium flower break virus (PFBV), and Pelargonium leaf curl virus (PLCV), were detected either singly or in combination in 59.2% of 800 samples. PLPV and PFBV infections were confirmed by dot-blot hybridisation. The most relevant viral infection found on Spanish asymptomatic geraniums was by Pelargonium line pattern virus (PLPV). Symptoms did not develop for 3 years on most of the PLPV infected geranium plants under greenhouse conditions.  相似文献   

7.
A new disorder exhibiting flower crinkle on Phalaenopsis orchids bearing white flowers has been observed in Taiwan, China and Japan for several years. This disorder decreased the flower longevity and was considered as a physiological syndrome. The objective of this study was to identify and characterize the real causal agent of this new Phalaenopsis disorder. Five plants of Phalaenopsis hybrids “V3” (Phal. Yukimai × Phal. Taisuco Kochdian) with flower crinkle symptoms were collected and tested by enzyme-linked immunosorbent assay with antisera against 18 viruses. The extract of leaves and flowers from one diseased plant (96-Ph-16) reacted positively only to antiserum against Odontoglossum ringspot virus (ORSV), while those from the other four plants (96-Ph-7, 96-Ph-17, 96-Ph-18 and 96-Ph-19) reacted positively to the antisera against ORSV and Cymbidium mosaic virus (CymMV). Five ORSV isolates, one each from flowers of those five diseased Phalaenopsis orchids, were established in Chenopodium quinoa. A CymMV culture was isolated from the flowers of one of the ORSV/CymMV mix-infected Phalaenopsis orchids (96-Ph-19). To determine the causal agent of the flower crinkle disease, healthy Phalaenopsis seedlings were singly or doubly inoculated with the isolated ORSV and/or CymMV. Results of back inoculation indicated that ORSV is the sole causal agent of the crinkle symptom on petals of Phalaenopsis orchid. The CP gene of the ORSV isolates from this study shared 97.3–100% nucleotide identity and 96.2–100% amino acid identity with those of 41 ORSV isolates available in GenBank. This is the first report demonstrating ORSV as the sole virus causing flower crinkle disease on Phalaenopsis orchids.  相似文献   

8.
Antisera against important orchid viruses, Cymbidium mosaic virus (CymMV) and Odontoglossum ringspot virus (ORSV), were separately produced using bacterially expressed recombinant capsid proteins (CP), instead of purified virus particles, as immunogens. These antisera were then designated as home-made CymMV CP antiserum (HM-Cy) and home-made ORSV CP antiserum (HM-OR). The high specificity of HM-Cy and HM-OR were confirmed by immunoblot. Their detection limits were determined using indirect-enzyme-linked immunosorbent assay (I-ELISA). Both HM-Cy and HM-OR showed low background reactivity to healthy plants and thus displayed a high S/H ratio (sample OD405/healthy control OD405) in tested orchids. The data indicated that our antisera were efficient and accurate in determination of negative and positive results in ELISA test as commercial antibodies. Therefore, these home-made antisera of CymMV and ORSV are suitable for the certification programme of orchids due to their low cost and high specificity. HM-Cy and HM-OR were further used for a field survey to study the incidence of CymMV and ORSV. The results showed that CymMV is more prevalent than ORSV in Taiwan.  相似文献   

9.
Pepino mosaic virus (PepMV, Genus Potexvirus, Family Flexiviridae) is a mechanically transmitted viral disease that has emerged as a significant problem of greenhouse tomato crops in Europe and around the world. Although previous studies in Cyprus suggested that the virus was not present on the island, in 2009 tomato fruits from two major tomato production areas exhibited symptoms of yellow mosaic and discolouration, similar to those induced by PepMV. Consequently, an extensive survey was conducted in all tomato producing areas of the country to identify the incidence and prevalence of PepMV in protected and open field tomato crops. Analysis of 3500 leaf samples from tomato plants and weeds with DAS-ELISA and real-time RT-PCR showed that PepMV was present in all tomato growing areas of the island. The virus was detected in both protected and open field tomato plants, as well as in 20 weed species in the families of Amaranthaceae, Chenopodiaceae, Compositae, Convolvulaceae, Malvaceae, Plantaginaceae and Solanaceae. All Cypriot isolates assayed belonged to the CH2 genotype. Biological assays with two Cypriot isolates showed that they could infect cultivated and weed species including Vigna unguiculata, Solanum melongena, Nicotiana tabacum, Malva parviflora, Sonchus oleraceus, Solanum nigrum, Convolvulus arvensis, Chrysanthemum segetum and Calendula arvensis. To our knowledge, this is the first study to report Chrysanthemum segetum and Calendula arvensis as hosts of PepMV.  相似文献   

10.
The genomic fragments of two open reading frames (ORFs) 1 and 2 of German and Canadian PAV isolates of Barley yellow dwarf virus (BYDV-PAV) were sequenced. Sequences only slightly differed from previously published sequences of this virus. Two polyclonal antisera against proteins encoded by ORFs 1 and 2 of a German ASL-1 isolate were developed using recombinant antigens expressed in E. coli as a fusion either to His6− or thioredoxin-tags. In Western blot analysis with total protein extracts from BYDV infected plants, antisera efficiently recognized the 99 kDa fusion protein expressed from ORF1 and ORF2 (P1–P2 protein). Later in infection the P1–P2 protein disappeared and two smaller proteins, revealing sizes of 39 and 60 kDa, could be detected.  相似文献   

11.
Apple chlorotic leaf spot virus (ACLSV) isolates from sand pear (Pyrus pyrifolia) were characterized by analyzing the sequences of their coat protein (CP) genes and serological reactivity of recombinant coat proteins (rCPs). The sequences of CP genes from 22 sand pear isolates showed a high divergence, with 87.3–100% identities at the nucleotide (nt) level and 92.7–100% identities at the amino acid (aa) level. Phylogenetic analysis on the aa sequence of CP showed that the analyzed ACLSV isolates fell into different clusters and all isolates from sand pear were grouped into a large cluster (I) which was then divided into two sub-clusters (A and B). Sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE), western blot and enzyme-linked immunosorbent assay (ELISA) analyses demonstrated that rCPs of eight ACLSV isolates (PP13, PP15-2, PP24, PP43, PE, PP54, PP56 and ACLSV-C) from two sub-clusters had different mobility rates and serological reactivity. The rCPs of five isolates grouped into the sub-cluster A showed stronger reactivity with antibodies against rCPs of a sand pear isolate ACLSV-BD and virions of a Japanese apple isolate P-205 than that with the antibody against a Chinese apple isolate ACLSV-C. Three isolates grouped into the sub-cluster B showed stronger reactivity with the antibody against ACLSV-C. The antigenic determinants of CPs from these eight isolates and isolates ACLSV-BD and P-205 were predicted. These results contribute to a further understanding of molecular diversity of the virus and its implication in serological detection.  相似文献   

12.
Two methods for the detection of Cucumber vein yellowing virus (CVYV) on infected plants were developed, based on the information provided by cDNA clones covering the 3-end of the genome of a Spanish isolate (CVYV-AILM). The sequenced portion of the CVYV-AILM genome showed a 96.6% aminoacid identity with that of a reported sequence of another CVYV isolate from Israel (Lecoq et al., 2000). The first detection method used a RNA specific probe for hybridization with nucleic acids extracted from infected plants. The probe was complementary to a portion of the CVYV genome including the C-terminal part of the NIb and most of the coat protein (CP) coding regions. The second detection method employed polyclonal antisera raised against recombinant viral CP expressed in bacteria. The specific antibodies were used to detect the presence of virus particles in plant extracts. Both procedures resulted in a highly specific detection of CVYV in plants infected with different isolates of the virus. No interference was observed with other cucurbit-infecting viruses. Sensitivities achieved were sufficient for routine diagnosis of the presence of the virus in plants.  相似文献   

13.
A weed survey conducted in 2004 and 2005 in Aydin province of Turkey showed that Solanum nigrum, Xanthium strumarium, Amaranthus retroflexus, Portulaca oleracea, Sonchus oleraceus and Datura stramonium were the most prevalent weeds in the cotton fields exhibiting Verticillium wilt. Verticillium dahliae Kleb. was recovered from A. retroflexus and X. strumarium in those cotton fields. This is the first report of V. dahliae occurring naturally in A. retroflexus in Turkey. Pathogenicity tests on cotton and weeds showed that the virulence of V. dahliae isolates from weeds was higher on cotton plants than on weeds, with the disease severity ranging from 31.7% to 98.0%. Disease severity of V. dahliae isolates was 54.7–93.9% on eggplant, 23.7–51.6% on cucumber and 11.0–16.4% on tomato, whereas it did not cause any disease symptoms, or only low levels, on pepper and bell pepper. Two vegetative compatibility groups (VCGs) were identified among seven tested weed isolates: VCG2A (two isolates) and VCG2B (three isolates) using international reference strains.  相似文献   

14.
Lettuce big‐vein associated virus (LBVaV, genus Varicosavirus) was shown to be responsible for characteristic necrotic symptoms observed in combination with big‐vein symptoms in lettuce breeding lines when tested for their susceptibility to lettuce big‐vein disease (BVD) using viruliferous Olpidium virulentus spores in a nutrient film technique (NFT) system. Lettuce plants showing BVD are generally infected by two viruses: Mirafiori lettuce big‐vein virus (MiLBVV, genus Ophiovirus) and LBVaV. New mechanical inoculation methods were developed to separate the two viruses from each other and to transfer both viruses to indicator plants and lettuce. After mechanical inoculation onto lettuce plants MiLBVV induced vein‐band chlorosis, which is the characteristic symptom of BVD. LBVaV caused a syndrome of necrotic spots and rings which was also observed earlier in lettuce plants inoculated in the NFT system, resembling symptoms described for lettuce ring necrosis disease (RND). This observation is in contrast with the idea that LBVaV only causes latent infections in lettuce. De novo next‐generation sequencing demonstrated that LBVaV was the only pathogen present in a mechanically inoculated lettuce plant with symptoms, providing evidence that LBVaV was the causal agent of the observed necrotic syndrome and thus fulfilling Koch’s postulates for this virus. The necrotic syndrome caused by LBVaV in lettuce is referred to as LBVaV‐associated necrosis (LAN).  相似文献   

15.
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.  相似文献   

16.
The complete nucleotide sequences of RNAs 1 and 2 of Rice stripe necrosis virus (RSNV) were determined and compared to the corresponding genomes of all sequenced, rod-shaped plant viruses. The genome organisation of RSNV RNA1 and RNA2 is nearly identical to that of Beet necrotic yellow vein virus (BNYVV) and Beet soil-borne mosaic virus (BSBMV), definitive species of the genus Benyvirus. As demonstrated for BNYVV and BSBMV, the RNA1 of RSNV also encodes a single ORF with putative replicase-associated motifs, which distinguishes benyviruses from all other viruses possessing rod-shaped particles. As described for BNYVV, RNSV RNA-2 also contains six ORFs: the capsid protein gene, the read-through protein gene, a triple gene block gene that codes for three different proteins, and a 17 kDa cysteine-rich protein. RNAs 3 and 4 (or 5 in the case of BNYVV), identified in natural infections of BNYVV and BSBMV, were not detected in any of the 44 RSNV cDNA clones obtained in this investigation. Nevertheless, phylogenetic and amino comparative acid sequence analyses demonstrated that RSNV is more closely related to BNYVV and BSBMV than to any other rod-shaped plant virus characterised to date.  相似文献   

17.
The complete nucleotide sequence of the genome of Nandina mosaic virus (NaMV), which has tentatively been assigned to the genus Potexvirus, is reported. The sequence is 6066 nt in length, excluding the poly(A) tail, and contains ORFs coding for proteins of 155, 25, 12, 13, and 21 kDa (ORFs 1–4 and the CP), respectively. The genomic organization of the virus and the signature motifs in the putative protein products are similar to the data reported for potexviruses for which complete sequences are known. Phylogenetic comparisons indicated that NaMV is most closely related to Plantago asiatica mosaic virus (PlAMV). Pairwise comparisons of the sequence data for these two viruses indicate that, based on criteria recently proposed for genera within the family Flexiviridae, NaMV and PlAMV should be considered to be strains/isolates of the same viral species. Both NaMV and PlAMV were first reported in 1976 but, as PlAMV was sequenced first, this name should take precedence with the name NaMV being relegated to a synonym.  相似文献   

18.
In 2005, severe leaf curling and yellowing were observed on tomato plants on Ishigaki Island. Because the symptoms were consistent with infection by a begomovirus, we used a polymerase chain reaction (PCR) with specific primers for begomovirus DNA-A and DNA satellite component (DNA-β) and detected products of the expected sizes from symptomatic tomato plant samples. DNA sequence analyses of the PCR products revealed that the symptomatic tomato plants were associated with Ageratum yellow vein virus (AYVV) infection. We confirmed AYVV transmission from the naturally infected weed host, Ageratum conyzoides, to healthy tomato plants by the insect vector Bemisia tabaci B biotype. This report is the first of AYVV occurrence in Japan.  相似文献   

19.
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20.
Three isolates of Chrysanthemum stem necrosis virus (CSNV) were obtained from chrysanthemum plants in distinct regions of Japan in 2006 and 2007. All the original host plants showed severe necrotic symptoms on the leaves and stems. Amino acid sequence data of the nucleocapsid protein genes of the three isolates (CbCh07A, TcCh07A, and GnCh07S) showed high identities with those of two other CSNV isolates, HiCh06A L1 from Japan and Chry1 from Brazil. Furthermore, for the first time the complete nucleotide sequence of the S RNA was determined for CSNV (isolate HiCh06A). In phylogenetic analysis based on the non-structural protein genes from the genus Tospovirus, HiCh06A L1 was placed in the same genetic group as Tomato spotted wilt virus (TSWV) and Impatiens necrotic spot virus. Host range examination for isolates HiCh06A L1 and CbCh07A showed that green pepper (cv. ‘Kyoyutaka’, ‘Saitamawase’, ‘Tosakatsura’, ‘L3 sarara’ and ‘L3 miogi’) and tomato (cv. ‘Sekaiichitomato’) were systemically susceptible hosts, whereas TSWV-resistant Solanaceae species, Capsicum chinense, Lycopersicon peruvianum and a TSWV-resistant cultivar of green pepper (cv. TSR miogi), were resistant.  相似文献   

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