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Lily symptomless virus (LSV) and Arabis mosaic virus (ArMV) cause severe losses of quantity and quality of lily flower and bulb production. Specificity, sensitivity and speed of detection methods for viruses need to be improved greatly to prevent LSV and ArMV from spreading from infected lilies. A dual IC‐RT‐PCR procedure for detection was developed in which the antibodies of LSV and ArMV were mixed and the mixture used to coat the PCR tubes. The particles of the two viruses were captured by the respective antibodies. Interference by other RNA viruses in infected lily was eliminated in the RT‐PCR. Also, an RNA extraction step was omitted. The dual IC‐RT‐PCR products of LSV and ArMV were 521 bp and 691 bp, respectively. The specificity of the method was validated; only LSV and ArMV of four viruses were detected by dual IC‐RT‐PCR. The sensitivity of the detection method is 1 mg leaf tissue and higher than DAS‐ELISA due to enrichment by dual immunocapture.  相似文献   

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The coat protein gene (CP) of an ordinary strain of Potato virus Y (PVYO) was cloned into the expression vector, pET‐28a(+). The insert was sequenced and analysis showed that the CP gene was in frame with intact N‐terminal 6X histidine tags. An approximately 35 kDa recombinant fusion protein was observed in inclusion bodies of induced Escherichia coli BL21 cells. This fusion protein was purified and used as antigen to raise polyclonal antibodies in rabbits. In Western blot and dot blot immuno‐binding assay (DIBA), both PVYO‐CP IgG and PVYO IgG strongly reacted with the recombinant CP. The PVYO‐CP IgG could detect PVYO in infected samples up to 1 : 3200 dilutions. A PVYO‐CP ELISA kit was prepared and compared with conventional ELISA kit based on purified virus particles (PVYO ELISA kit). The PVYO‐CP ELISA kit consistently detected the PVYO in DAS‐ELISA of field samples and was as effective as PVYO ELISA kit.  相似文献   

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Bean pod mottle virus (BPMV) has been identified as an important pathogen for plant quarantine in China because large quantities of soya bean seeds (approximately 7 × 107 tons) are imported annually. To develop a practical detection programme for BPMV, a cocktail enzyme‐linked immunosorbent assay (ELISA) nested RT‐PCR using a combination of serological and molecular methods was designed for soya bean seeds. The single‐vessel detection assay was performed in a 96‐well ELISA plate, which served as a carrier for the subsequent nested RT‐PCR assay. Assay specificity was demonstrated by the production of the expected 330‐ and 296‐bp bands using the external and internal primers, respectively. This method was 104‐fold more sensitive than immunocapture‐RT‐PCR (IC‐RT‐PCR). In particular, it is important to note that this assay resulted in successful micro‐extraction from soya bean seeds and combined the advantages of each individual technique. The cocktail ELISA nested RT‐PCR is a specific, sensitive, rapid and economical procedure to rapidly identify and characterize BPMV and could be suitable for both primary‐level platforms and laboratories.  相似文献   

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Citrus is one of the most economically important fruit crops in the world. Citrus psorosis is a serious disease affecting mainly oranges and mandarins in Argentina and Uruguay. The causal agent is Citrus psorosis virus (CPsV), an ophiovirus with a tripartite ssRNA genome of negative polarity. The coat protein (CP), the most abundant viral protein in infected plants, has been used to detect CPsV by TAS‐ELISA, but only biological indexing, requiring 1 year, is the current and validated technique for diagnosis of citrus psorosis. In this study, a SYBR Green RT‐qPCR protocol was developed, with primers designed to the most conserved region of the cp gene. We tested their specificity and sensitivity in comparison with TAS‐ELISA. This RT‐qPCR was applied successfully to field samples from Argentina, to a variety of isolates from different countries maintained in the greenhouse, to young seedlings and old trees from a psorosis natural transmission plot, and to transgenic citrus expressing the cp gene of CPsV or a fragment thereof. This method allowed accurate quantification of viral titer and cp gene expression in transgenic plants, which could not be detected previously. The sensitivity and reliability of quantitative CPsV detection were improved with greater speed using commercial reagents, and the sensitivity was three orders of magnitude higher than that of TAS‐ELISA. All these data encourage its validation.  相似文献   

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  总被引：2，自引：0，他引：2  
Orchids are some of the most important ornamental flowers. Cymbidium mosaic virus (CymMV) and Odontoglossum ringspot virus (ORSV) are the most prevalent and economically important viruses affecting orchids in China. In this study, 20 CymMV and 28 ORSV isolates were selected for genetic diversity analysis. The CymMV isolates shared 84.6–100% and 89.5–100% identities of coat protein (CP) at the nucleotide (nt) and amino acid (aa) levels, respectively. The identities of ORSV isolates were 96.4–100% (nt) and 92.5–99.4% (aa). The CP genes of CymMV were found to have genetic diversity, and the CP genes of ORSV were genetically conservative. These results can aid in designing effective disease‐control strategies.  相似文献   

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Citrus tristeza virus (CTV), the causal agent of tristeza disease, causes the devastating diseases worldwide. In Taiwan, complex cultivars and long‐term infection by CTV result in more than 90% of infected citrus trees, but local strain identification and classification are still incomplete. Here, six CTV strains were categorized by grafting onto eight citrus cultivars and the pathological characteristics of the stem‐pitting mild strains were identified. After 6 months of inoculation, the pummelo stem‐pitting severe strain (CTV‐Pum/SP/T1) only caused severe symptoms in Wentan pummelo (WP) and the mild strain (CTV‐Pum/M/T5) was symptomless in every cultivar; the sweet orange (SO) stem‐pitting severe strain (CTV‐SwO/SP/T7) affected SO, WP and Ponkan mandarin (PM), and the mild strain (CTV‐SwO/M/T51) caused no symptoms in SO except for WP; the mandarin stem‐pitting severe strain (CTV‐Man/SP/T46) caused severe impacts in PM, WP and Eureka lemon, whereas the mild strain (CTV‐Man/M/T2) only caused severe stem‐pitting in WP. The full‐length sequencing of both pummelo stem‐pitting strains and phylogenetic analysis revealed that CTV‐Pum/SP/T1 and CTV‐Pum/M/T5 were related to the HA18‐9 and HA16‐5 strains from Hawaii, respectively. Moreover, recombination analysis revealed that TCT repeat sequences existed at open reading frame 1a in both the CTV‐Pum/SP/T1 and the T36 strains from the United States, indicating that the possible evolution relationship between two regions. Furthermore, improved universal and specific primer pairs were designed for more specific, sensitive detection to meet the needs for quarantine and early prevention. The understanding of strain pathogenicity and genomic analysis provided further characterization of each strain and enabled practical challenge inoculation against CTV disease.  相似文献   

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Soybean crops showing systemic mottling, mosaic and leaf deformation were observed at high disease incidences (25.1–71.0%) in the kharif season of 2011 and 2012 in the experimental farm of the Indian Agricultural Research Institute (IARI), New Delhi. Symptomatic soybean leaves contained flexuous particles (650 × 12 nm), suggesting an infection by a Carlavirus. The causal virus was characterized as a strain of Cowpea mild mottle virus (CPMMV) on the basis of mechanical inoculation, whitefly transmission, seed transmission and sequencing of the viral genome. This is the first report of natural infection by a distinct strain of CPMMV in soybean in India.  相似文献   

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The key regions in Panama involved in open field‐ and greenhouse‐grown commercial tomato production, including the Chiriquí, Veraguas, Herrera, Los Santos, Coclé and Panama Oeste provinces, were surveyed for the incidence and distribution of begomoviruses in the growing seasons of 2011 and 2012. The surveys took place in 14 of the 51 districts of the above‐mentioned provinces and comprised all relevant tomato production areas of the provinces. A total of 28 tomato plots were surveyed. The exact location of each plot was geo‐referenced using a hand‐held Global Positioning System unit. In total, 319 individual tomato plants (181 in 2011 and 138 in 2012) were sampled. Plants displayed diverse combinations of virus‐like symptoms of different severity, including necrosis, yellowing, mosaic, mottling, rolling, curling, distortion and puckering of leaves, reduced leaf size, and stunted growth. DNA was extracted from each plant for a subsequent polymerase chain reaction (PCR) analysis, using two sets of degenerate primers able to detect members of the genus Begomovirus. The samples displaying a positive reaction were subsequently analysed with specific primer pairs to identify the affecting begomoviruses. A total of 42.3% of all collected samples showed a positive signal to PCRs. Three begomovirus species were detected with the species‐specific set of primers; in particular, in the samples obtained in 2011, Potato yellow mosaic Panama virus (PYMPV), Tomato leaf curl Sinaloa virus (ToLCSiV) and Tomato yellow mottle virus (TYMoV) were detected, while in the 2012 samples, only PYMPV and ToLCSiV were found. To our knowledge, this is the first reported incidence of ToLCSiV and TYMoV in Panamanian tomato crops.  相似文献   

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Beet yellows virus (BYV), a member of the Closteroviridae family, is one of the most important sugar beet yellowing viruses. The nine ORFs of BYV genome encode different proteins required for BYV life cycle. We sequenced a part of the genome of BYV Iranian isolate consisting of ORF6, ORF7 and ORF8. The primer pair BYVA/Z was used for amplification of this region in RT‐PCR. The amplicon (1615 bp) was cloned and sequenced. Comparisons showed the amplified segment is corresponding to ORF6, ORF7 and ORF8 of BYV genome encoding coat protein, p20 and p21 proteins, respectively. The ORF7 of BYV Iranian isolate overlaps with ORF6 and ORF8 in four and 26 nucleotides at 5′ and 3′ ends, respectively. The ORF7 of Iranian isolate of BYV was sequenced completely. However, approximately 24 nt. from the beginning of ORF6 and 23 nt. from end of ORF8, including the stop codon, were not determined. ORF6, ORF7 and ORF8 showed the highest similarity at nucleotide (98.3, 99.4 and 99.2%) and amino acid (97.4, 98.9 and 100%) sequence levels, with BYV Ukrainian isolate. Phylogenetic analysis of the deduced amino acid sequences of ORF6, ORF7 and ORF8 revealed closer relationship of Iranian isolate of BYV with BYV Ukrainian isolate than other BYV isolates available at GenBank.  相似文献   

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Observations made in Mali strongly suggest that Rice yellow mottle virus (RYMV) is spread by weaverbirds (Quelea quelea) below and around baobab trees (Adansonia digitata) in which they nest. Rice leaves in bird nests appeared to be infected. In Spain, an infection of Southern bean mosaic virus (SBMV) in string (climbing) beans (Phaseolus vulgaris) was apparently introduced and spread by sparrows (Passer domesticus) judging from the damage caused on flowers and bean pods. Damaged leaves and pods on SBMV‐infected plants were also found in a screenhouse visited by sparrows and bulbuls (Pycnonotus barbatus) in Morocco. These observations showed that both viruses could be spread by birds when either collecting infected leaves for nesting or feeding on infected plants.  相似文献   

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The virus in naturally infected, stunted Chinese mallow plants and mosaic leaves was identified as Cucumber mosaic virus (CMV). Six symptomatic plants and one symptomless plant were collected in Chongqing, China. DAS‐ELISA suggested CMV was likely associated with the diseased Chinese mallow. Double‐stranded RNA was extracted from the samples, analysed by RT‐PCR, and the coding sequences of their coat proteins (CPs) were sequenced. The results further confirmed CMV was the pathogen causing Chinese mallow stunted, mosaic disease. The isolate was named CMV‐DXC. The full sequence of CMV‐DXC CP was determined, and it had the highest nucleotide identity (99.4%) of those of CMV‐lily, CMV‐WSJ and CMV‐Hnt, respectively. Phylogenetic analysis shows that CMV‐DXC belongs to CMV subgroup II. To our knowledge, this is the first report of CMV infecting Chinese mallow in China.  相似文献   

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RNA silencing is a powerful technology for molecular characterization of gene functions in plants. A commonly used approach to the induction of RNA silencing is through genetic transformation. A potent alternative is to use a modified viral vector for virus‐induced gene silencing (VIGS) to degrade RNA molecules sharing similar nucleotide sequence. Unfortunately, genomic studies in many allogamous woody perennials such as peach are severely hindered because they have a long juvenile period and are recalcitrant to genetic transformation. Here, we report the development of a viral vector derived from Prunus necrotic ringspot virus (PNRSV), a widespread fruit tree virus that is endemic in all Prunus fruit production countries and regions in the world. We show that the modified PNRSV vector, harbouring the sense‐orientated target gene sequence of 100‐200 bp in length in genomic RNA3, could efficiently trigger the silencing of a transgene or an endogenous gene in the model plant Nicotiana benthamiana. We further demonstrate that the PNRSV‐based vector could be manipulated to silence endogenous genes in peach such as eukaryotic translation initiation factor 4E isoform (eIF(iso)4E), a host factor of many potyviruses including Plum pox virus (PPV). Moreover, the eIF(iso)4E‐knocked down peach plants were resistant to PPV. This work opens a potential avenue for the control of virus diseases in perennial trees via viral vector‐mediated silencing of host factors, and the PNRSV vector may serve as a powerful molecular tool for functional genomic studies of Prunus fruit trees.  相似文献   

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Blueberry red ringspot virus (BRRSV) isolates have been investigated for genetic diversity. Nucleotide sequences of the coat protein (CP) gene of 19 isolates from Poland, Czech Republic, Slovenia and the United States were analysed. The nucleotide and amino acid sequence identity were 92–100% and 89–100%, respectively. Estimations of the distribution of synonymous and non‐synonymous changes indicated negative selection within the analysed CP gene and confirmed the genetic stability of the virus. At a capsid protein level, our results revealed BRRSV to be distinct from other, recombination‐prone pararetroviruses.  相似文献   

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