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1.
A. A. BRUNT 《EPPO Bulletin》1989,19(3):437-451
The viruses and virus-like pathogens transmitted by zoosporic fungi are reviewed. The nine furoviruses (and possible members of the group), with labile rod-shaped particles, have nearly all been shown to be transmitted by plasmodiophoromycete vectors. As they have been reviewed extensively elsewhere, they are covered only briefly; important examples are beet necrotic yellow vein furovirus and potato mop-top furovirus. Five viruses with filamentous particles, tentatively recognized as poty viruses, are transmitted by Polymyxa graminis. Within this group, wheat yellow mosaic virus should be considered to include wheat spindle streak mosaic virus, while the M and NM forms of barley yellow mosaic virus, the best known members of the group, should probably be regarded as distinct viruses. Chytrids (especially Olpidium brassicae) transmit a variety of viruses in different groups (e.g. tobacco necrosis necrovirus, lettuce big-vein virus, melon necrotic spot carmovirus, red clover necrotic mosaic dianthovirus). Finally, several diseases caused by uncharacterized pathogens appear to be transmitted by O. brassicae: freesia leaf necrosis, lettuce ring necrosis, pepper yellow vein, watercress chlorotic leaf spot.  相似文献   

2.
F(ab')2 and protein A ELISA tests were used to investigate the serological affinities of five fungally transmitted cereal viruses: barley yellow mosaic (BaYMV), barley mild mosaic (BaMMV), oat mosaic (OMV), wheat yellow mosaic (WYMV) and oat golden stripe (OGSV). Within this group only BaYMV and WYMV were related. Chinese and UK isolates of BaYMV appeared to be similar. In tests using antisera to 29 other elongated viruses, BaYMV was related to one isolate of bean yellow mosaic poty virus (BYMV-G) and OGSV had affinities with BYMV-G, potato virus M, red clover vein mosaic (both carlaviruses) and perhaps Hordeum mosaic virus. The results were confirmed in immunoelectron microscopic tests. No affinities were found for BaMMV, OMV or WYMV.  相似文献   

3.
In Germany the furovirus Soil-borne cereal mosaic virus (SBCMV) and the bymovirus Wheat spindle streak mosaic virus (WSSMV) occur often together particularly in several rye production areas. Soil-borne wheat mosaic virus (SBWMV), a wheat infecting furovirus, has so far been found only in one field near Heidelberg. Each of these viruses is transmitted by Polymyxa graminis. The cultivation of resistant varieties is the only promising measure to prevent yield losses caused by soil-borne viruses. Resistance of wheat against the bymovirus WSSMV is comparable to the immunity of barley to the bymoviruses Barley yellow mosaic virus and Barley mild mosaic virus. In case of immunity no virus multiplication is observed in resistant cultivars. In contrast, all wheat cultivars are hosts of the furoviruses. All cultivars – including the resistant ones – can be infected following mechanical inoculation with SBWMV and SBCMV. Resistance to furoviruses is based on reduced levels of virus multiplication in roots and on inhibition of virus movement from roots to leaves. Because of the inhibited virus movement from roots to aerial parts of plants this type of resistance is referred to as translocation resistance. In spite of the different resistance mechanisms the absence of virus symptoms on the leaves is a common selection criterion for both immunity and translocation resistance. Therefore, the symptom free development of plants on uniformly infested fields is the best criterion for selecting wheat lines with resistance to soil-borne viruses. The limited suitability of other selection methods is discussed.  相似文献   

4.
Ullucus tuberosus (ulluco) is a tuber-forming species that has become a novel crop in highland and temperate maritime climates. Eight viruses have been previously reported infecting Ullucus, including Andean potato latent virus (APLV), a quarantine virus within the European Union. No reference sequences have been published for the viruses previously described from U. tuberosus. Plants grown in the UK for the internet trade were tested for the presence of quarantine viruses using ELISA and real-time RT-PCR. ELISA positive results were obtained for APLV and multiple other viruses. A similar suite of viruses was detected at a second outbreak site linked to horticultural trade. Virus identification was by high-throughput sequencing (HTS) using a ribosomal RNA (rRNA)-depleted total RNA approach. Analysis of viral contigs indicated the presence of several novel viruses closely related to, but not consistent with, the viruses indicated by ELISA. Further confirmatory testing by real-time RT-PCR indicated that two tymoviruses, tentatively named Ullucus tymovirus 1 and Ullucus tymovirus 2, were more closely related to each other (85% identity), than to APLV or Andean potato mild mosaic virus (63–66% identity). APLV could not be confirmed from either site by either HTS or PCR. A novel tobamovirus (Ullucus tobamovirus 1) was only detected at the initial outbreak site. A novel polerovirus (Ullucus polerovirus 1) and a distinct genotype of Papaya mosaic virus were detected from both outbreak sites. Deploying HTS during a plant health outbreak demonstrates the potential of this approach to give rapid, accurate diagnosis.  相似文献   

5.
Four virus isolates were obtained in FRG and Sweden from sugarbeet roots which had become infected via the soil. All isolates had rod-shaped particles of four or five different lengths. Serologically they were unrelated to beet necrotic yellow vein furovirus and several other viruses of a similar morphology including two serologically distinct sugarbeet isolates from California (US). Our isolates were, however, serologically related to beet soil-borne furovirus which has been described in England. They could be subdivided into two serotypes.  相似文献   

6.
The aphid‐transmitted viruses Potato virus Y (PVY) and Potato virus A (PVA) commonly affect seed potatoes in the UK. The transmission efficiency for aphid species is used to calculate a potential transmission risk and is expressed as a relative efficiency factor (REF). These REFs have not previously been calculated for UK strains of viruses or aphid clones. Using a previously published method, REFs have been calculated for the aphid species and viruses commonly occurring in UK potatoes. The efficiency of transmission of Myzus persicae is nominally set to a REF of 1 and REFs for other species are calculated relative to this. These data represent the first set of REFs calculated for PVA transmission. Macrosiphum euphorbiae (REF 0.91) was almost as efficient as M. persicae at PVA transmission. The data were further analysed to compare transmission rates of PVY and PVA using a binomial (logit) generalized mixed model to take into account the potential influence of variation in virus titre between leaves. This approach found that there is little variation between the efficiency of transmission between clones of each aphid species or between strains within a virus species. This is a first report that Aphis fabae, Metopolophium dirhodum, Sitobion avenae, Acyrthosiphon pisum and Cavariella aegopodii have the ability to vector PVA. This study also represents a first report that C. aegopodii has the ability to vector PVY and confirms the potential of S. avenae, A. fabae, M. euphorbiae and Rhopalosiphum padi as important PVY vectors.  相似文献   

7.
A polyprobe for the simultaneous detection by non-isotopic molecular hybridisation has been developed to detect any of the following six viruses causing important economic losses in tomato crops: Tomato spotted wilt virus, Tomato mosaic virus, Pepino mosaic virus, Cucumber mosaic virus, Potato Y virus and Parietaria mottle virus. The polyprobe detected all six viruses with similar sensitivity to that obtained using individual riboprobes. In addition, we evaluated the possible use of the tissue-printing as a sample preparation technique applied to routine diagnosis of tomato plants with the polyprobe. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.  相似文献   

8.
Cassava common mosaic disease (CCMD) has been reported in all regions where cassava is grown in the Americas and the causal agent, Cassava common mosaic virus (CsCMV), has been identified as a mechanically transmitted potexvirus (Alphaflexiviridae). In Argentina, cassava is grown mainly in the northeast (NEA) region that shares borders with Brazil and Paraguay. Increasing incidences of CCMD were observed during the years 2014 to 2016 associated with severe leaf mosaic symptoms and yield reductions where the occurrence of CsCMV was confirmed by RT‐PCR and sequencing. In this work, the virus has been successfully purified and a double‐antibody sandwich (DAS‐) ELISA test has been developed from an Argentinean isolate of CsCMV to extend the diagnostics of the disease. A collection of 726 samples was screened and CsCMV was detected with 100% prevalence in the NEA region. Additional co‐infecting viruses were detected in some plants (64.4%); in these, CCMD symptoms correlated with CsCMV only, although more severe symptoms could be observed in mixed infected plants. Sequence analysis of the conserved RdRp domain showed a wider diversity of CsCMV isolates. Interestingly, a separate phylogenetic cluster was formed by isolates from the NEA region that only shared 77.1% to 80.3% nucleotide identity with the other clusters. These results indicate the presence of mixed strains occurring in the NEA region and suggest the presence of geographically distinct strains of CsCMV in South America.  相似文献   

9.
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   

10.
ABSTRACT Four monoclonal antibodies (MAbs) were prepared against an isolate of soilborne wheat mosaic furovirus from Oklahoma (SBWMV Okl-7). Three MAbs had different reactivities in tests on SBWMV isolates from Nebraska (Lab1), France, and Japan. One MAb (SCR 133) also reacted with oat golden stripe furovirus. None of the MAbs cross-reacted with other rod-shaped viruses including beet necrotic yellow vein furovirus, potato mop-top furovirus, and tobacco rattle tobravirus. Sequence analysis of nucleotides between 334 and 1,000 of RNA 2, the region that encodes the coat protein (CP) and the first 44 amino acids of a readthrough protein, of the four SBWMV isolates revealed up to 27 base changes from the published sequence of a Nebraska field isolate of SBWMV. Most changes were translationally silent, but some caused differences of one to three amino acids in residues located near either the N- or C-terminus of the CPs of the different isolates. Two further single amino acid changes were found at the beginning of the readthrough domain of the CP-readthrough protein. Some of these amino acid changes could be discriminated by MAbs SCR 132, SCR 133, and SCR 134. Peptide scanning (Pepscan) analysis indicated that the epitope recognized by SCR 134 is located near the N-terminus of the CP. SCR 132 was deduced to react with a discontinuous CP epitope near the C-terminus, and SCR 133 reacted with a surface-located continuous epitope also near the C-terminus. Predictions of CP structure from computer-assisted three-dimensional model building, by comparison with the X-ray fiber diffraction structure of tobacco mosaic virus, suggested that the three CP amino acids found to differ between isolates of SBWMV were located near the viral surface and were in regions predicted to be antigenic.  相似文献   

11.
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12.
Leaf samples of Lablab purpureus collected from two agroecological zones of Nigeria—the northern guinea savanna zone (NGSZ) and the derived savanna zone (DSZ)—were infected with viruses when serologically indexed against available antisera. Approximately 31.1 and 81.1% of the leaf samples collected from the NGSZ and DSZ, respectively, were infected. Seven viruses were found: Bean common mosaic virus (BCMV), Cowpea aphid-borne mosaic virus (CABMV), Cucumber mosaic virus (CMV), Cowpea mottle virus (CPMoV), Cowpea severe mosaic virus (CPSMV), Southern bean mosaic virus (SBMV) and Tobacco mosaic virus (TMV) were detected from samples collected from NGSZ, while CMV, CPMoV, Cowpea mosaic virus (CPMV) and CPSMV were detected from samples from DSZ.  相似文献   

13.
Alstroemeria samples collected in the UK were tested for a range of viruses using ELISA. Alstroemeria mosaic virus (AlMV), alstroemeria carlavirus (AlCV), lily symptomless virus (LSV), cucumber mosaic virus (CMV) and tobacco rattle virus (TRV) were detected either singly or in combination in 67.5% of 203 samples. AlCV and LSV isolates from Alstroemeria and lily were studied and characterised serologically using existing antisera, and by PCR, using primers to an 11kDa open reading frame (ORF) unique to carlaviruses and to the coat protein gene of LSV. Sequences of isolates of AlCV and LSV from the coat protein gene were 94–99% similar and were 99% similar in the 11kDa ORF, supporting the view that these are strains of the same virus.  相似文献   

14.
The virus causing horsegram (Macrotyloma uniflorum) yellow mosaic disease has been shown to be a typical Old World bipartite begomovirus. The viral origin of the disease has been established through agroinoculation of horsegram using partial tandem repeat clones of both DNA-A and DNA-B. The DNA-A genome shows less than 89% identity with the corresponding sequences of all the begomoviruses in the databases earlier to this sequence submission (AJ627904). Therefore Horsegram yellow mosaic virus (HgYMV-[IN:Coi]) can be considered to be a new species of the genus Begomovirus (family Geminiviridae). Phylogenetic analysis shows that this virus is part of the cluster of mungbean yellow mosaic viruses of legumes from South and South East Asia.  相似文献   

15.
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   

16.
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17.
Characterization of a New Barley Mild Mosaic Virus Pathotype in France   总被引：2，自引：1，他引：1  
In March 2002 in a French field, severe mosaic symptoms appeared on plants of the barley cultivar Tokyo with the rym5 locus controlling resistance to all European strains of barley yellow mosaic virus (BaYMV) and barley mild mosaic virus (BaMMV). Electron microscopic examination revealed that the disease symptoms were associated with the presence of flexuous particles which resemble bymoviruses. From these observations and after enzyme-linked immunosorbent assay analysis it was first determined that the plants could be infected by BaMMV and BaYMV. Mechanical transmission of these viruses to the barley cultivar Magie susceptible to both viruses was only possible for BaMMV. This new pathotype (BaMMV-Sil) from Sillery (Marne Department, 51, France), in contrast to another mechanically transmitted French BaMMV isolate (BaMMV-MF), could be transmitted mechanically to two barley cultivars (Tokyo, Misato Golden), Arachis hypogaea, Datura stramonium and Lactuca sativa. BaMMV-Sil was indistinguishable from three BaMMV isolates from Germany (G), Japan (Ka1) and France (PF) by monoclonal antibodies in ELISA while the Japanese isolate (Na1) and BaMMV-MF were distinguishable from all. The sequence of the 3-terminal region of BaMMV-Sil RNA1 was determined. Comparison with previously published sequence data of capsid proteins indicated that BaMMV-Sil was closely related to BaMMV-Ka1, BaMMV-G and another German isolate (BaMMV-ASL1). Resistance-breaking BaMMV strains able to infect cultivars carrying the rym5 locus have also been described in Japan (BaMMV-Na1) and Korea (BaMMV-Kor). No specific amino acid differences were detected between the capsid proteins of BaMMV-Sil, BaMMV-Na1, BaMMV-Kor and those BaMMV isolates that do not overcome the rym5 resistance gene. These results indicate that BaMMV-Sil is a new pathotype of BaMMV in France and suggests that the capsid protein is not the determining factor of the pathogenicity towards the resistance gene rym5.  相似文献   

18.
在田间的小麦丛矮病非典型病株申常常分离到北方禾谷花叶病毒(NCMV)及玉米粗缩病毒(MRDV)两种病原物。单独用前者接种,仅表现小麦丛矮症,单独用后者接种,仅表现小麦蓝矮症,即植株矮化、暗绿、分蘖减少,叶坚挺。两者混合侵染时,往往表现两者的混合症状,但以何种病毒占优势而倾向于优势病毒的症状。典型丛矮症植株中电镜检出弹状病毒粒体,40—70×270—400nm尺度与日本报导的稍异。典型丛矮病株中不存在玉米粗缩病毒的粒体。小麦丛矮病毒很可能是北方禾谷花叶病毒的一种地方性株系。  相似文献   

19.
The presence of viruses in the weedLeonotis nepetaefolia in central México is reported from two field surveys.L. nepetaefolia, with viral-like symptoms such as mosaic, leaf deformation and calico, was observed growing next to cultivated fields in the Valley of Atlixco, Puebla, an important agricultural region in Mexico. The viruses harbored by this plant were characterized biologically, serologically and by molecular methods. The viruses detected wereAlfalfa mosaic virus (AMV),Cucumber mosaic virus (CMV), a satellite RNA of CMV (CMV satRNA) andTobacco mosaic virus (TMV). This last one was detected only during the first survey. CMV was the predominant virus found in both surveys, and was associated mostly to mosaic symptom. Phylogenetic analysis based on the coat protein gene sequence of CMV indicated that this isolate belongs to subgroup IA and confirmed that it is a mosaic-inducing isolate, whereas AMV belongs to subgroup II. Finally, CMV satRNA was found to be a non-necrogenic ameliorative variant, both by symptomatology and by phylogenetic analysis. Our results suggest thatL. nepetaefolia is a reservoir for several viruses in central Mexico, and given its wide distribution in several parts of the world, its role as a virus reservoir could be more general. http://www.phytoparasitica.org posting Aug. 31, 2005.  相似文献   

20.
Polymyxa graminis is the vector of several important viruses, including Soilborne cereal mosaic virus, Wheat spindle streak mosaic virus, Barley yellow mosaic virus and Barley mild mosaic virus, of winter cereals worldwide. Surveys were carried out to detect these viruses and their vector P. graminis in 300 soil samples from the main wheat and barley production areas of the Anatolian part of Turkey collected in May 2002, June 2004 and May 2005. For these surveys, various susceptible wheat and barley cultivars were pot grown in the collected soil samples in a greenhouse and then analysed using ELISA and RT-PCR to detect the presence of different virus species. In addition, a combination of light microscopy following roots staining with acid fuchsin and PCR was used for detection of P. graminis. All soil samples analysed were found to be free of these soilborne viruses and their vector.  相似文献   

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