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1.
Potato spindle tuber viroid (PSTVd) is an EPPO A2-listed quarantine pathogen and its detection in large scale surveys requires complex decision schemes. In this study, a simple and rapid application of direct-RT-PCR was evaluated together with dot blot hybridization for the detection of PSTVd in dormant potato tubers harvested from primary infected plants, as well as in tomato and solanaceous ornamental plants. In all infected dormant potato tubers tested, both direct-RT-PCR and dot blot hybridization detected two different PSTVd isolates, with direct-RT-PCR being ten times more sensitive than dot blot. Similarly, in infected tomato and Brugmansia spp., PSTVd was detected by direct-RT-PCR with higher sensitivity compared to that of dot blot hybridization. However, in Brugmansia spp., a ten-fold decrease of the typical working concentration of the sap was required for an unequivocal detection of the viroid by direct-RT-PCR. The potential to use direct-RT-PCR for routine PSTVd examination is discussed.  相似文献   

2.
Potato spindle tuber viroid (PSTVd) was transmitted by Myzus persicae to Physalis floridana from P. floridana plants that also were infected with potato leafroll luteovirus (PLRV), whereas it was not transmitted by aphids from plants infected with PSTVd alone. Dot-blot hybridisation was used to detect PSTVd. The results indicate that PLRV can assist PSTVd in its transmission by M. persicae. Doubly infected, aphid-inoculated P. floridana plants from the previous experiment were used as the source plants in aphid transmission tests to the tomato cv. Rutgers, P. floridana and Datura stramonium. PSTVd was detected in 17 of 30 plants of tomato. The viroid was not detected by dot-blotting in any plant of P. floridana and D. stramonium in this experiment, but it was recovered from some plants by sap inoculation of the Rutgers plants. Treatment with RNase A of PLRV preparations purified from doubly infected plants indicated that PSTVd was encapsidated by PLRV particles.  相似文献   

3.
Viroids of the genus Pospiviroid are able to induce diseases in a wide range of host plants including important crop species. Although occasional disease outbreaks of Potato spindle tuber viroid (PSTVd) and closely related pospiviroids have been reported in potato and tomato, recent studies found an increase in number of latent infections in ornamental solanaceous species. In order to verify the presence of PSTVd and other pospiviroids in Croatia, a survey was conducted between 2009 and 2012. A total of 182 samples belonging to five ornamental species and two solanaceous crops were analyzed. Eight plants belonging to two different species (Solanum jasminodes and Lycianthes rantonnetii) were found infected by PSTVd and, in addition, one S. jasminoides plant infected by Tomato apical stunt viroid (TASVd). Viroid infection was confirmed by mechanical inoculation on tomato plants to observe symptom expression. Molecular characterization of the isolates was done and complete viroid sequences were submitted to the GenBank. This is the first evidence of the presence of PSTVd and TASVd and their variability in Croatia.  相似文献   

4.
In autumn 2006 in the Netherlands, Potato spindle tuber viroid (PSTVd) infections were detected in 42·3 and 71·9% of professionally grown lots of Brugmansia spp. and Solanum jasminoides respectively. The infected lots contained 73 985 and 431 374 plants, respectively, demonstrating the presence of many potential viroid sources for tomato ( Solanum lycopersicum ). PSTVd was identified in cultivars of Brugmansia × candida , B. × flava , B. sanguinea , B. suaveolens and unspecified Brugmansia species/cultivars. Most infected lots of Brugmansia spp. originated from a single Dutch nursery; most infected lots of S. jasminoides originated abroad. Sequence analysis revealed that the PSTVd genomes from Brugmansia spp. contained an average of 360 nt, whereas all genomes from S. jasminoides except one consisted of 357 nt. Furthermore, the collective PSTVd genotypes showed polymorphism at four or more positions, except for two cases in which genotypes from Brugmansia spp. and S. jasminoides were identical. Phylogenetic studies showed that PSTVd genotypes from Brugmansia spp. and S. jasminoides grouped apart from each other and from PSTVd isolates from potato ( Solanum tuberosum ) and Physalis peruviana . The PSTVd genotypes from tomato did not form a separate cluster, but were dispersed over clusters of vegetatively or partly vegetatively propagated plant species, i.e. potato, P. peruviana and S. jasminoides . Moreover, mechanical inoculation of the predominant PSTVd genotypes from S. jasminoides to tomato was successful. These results provide evidence that vegetatively propagated, solanaceous plant species have been sources of infection for tomato crops in the past.  相似文献   

5.
In 2014, potato spindle tuber viroid (PSTVd) was identified in a potato clone originating from a breeding company in the Netherlands. This clone was submitted for micro propagation and therefore tested for PSTVd and a number of other pathogens. This finding of PSTVd initiated actions to track and eradicate the infections. In addition to the finding at the breeding company, PSTVd was also found at a research institute. At both locations the viroid was eradicated following extended testing and discarding of infected plants. Additional surveys including testing of each individual plant in all crossing glasshouses and random samples of pre-basic and basic seed potatoes, revealed no further infections in the Netherlands. This result concurred with the fact that mechanical spread of PSTVd in the field is not likely under climatic conditions in the Netherlands. Therefore, vegetative propagation seems the most important pathway for maintaining and spreading of PSTVd. Based on the evaluation of this outbreak, it was concluded that potato germplasm poses the highest risk of introducing this viroid in potatoes in the Netherlands.  相似文献   

6.
The work described here formed part of the EU SMT DIAGPRO project, to develop diagnostic protocols for 18 regulated pests. The Potato spindle tuber pospiviroid (PSTVd) protocol was developed primarily for testing in vitro‐ and glasshouse‐grown potato plants for the purposes of post‐entry quarantine and the production of pathogen‐tested nuclear stock. After a performance audit of methods used by 12 laboratories in Europe and America by ring testing, four methods were chosen for multilaboratory validation. For most laboratories, the detection limits were 10–20 mg of PSTVd‐infective tissue for R‐PAGE; 0.25–0.5 mg for DIG‐probe; 0.062 mg for RT‐PCR; and 0.0155 mg for TaqMan (this was the lowest weight of infective tissue tested). Some laboratories were able to extend the detection limit to 0.0155 mg for DIG‐probe and RT‐PCR. The DIG‐probe and R‐PAGE are recommended as primary detection methods, with confirmation of viroid presence by any of the four validated detection methods. Specific diagnosis requires the viroid to be sequenced. Other methods may be used for primary detection, providing that they preferably detect all PSTVd isolates and other Pospiviroids that have the potential to infect potato, and detect viroid in at least 1/10 of the tissue weight normally tested per plant.  相似文献   

7.
The infectious yellows disease of glasshouse lettuce, endive and cucumber is further described and now also reported from ornamental pumpkin and the weedEpilobium sp. growing in an infested glasshouse, and from chicory witloof grown in the open near that glasshouse. In the Netherlands it was of major importance in cucumber and lettuce from 1978 to 1980, but has rapidly declined since then because of intensive whitefly control and better overall hygiene. The pathogen could neither be transmitted mechanically nor with aphids and via seed of infected lettuce plants, and no virus particles could be detected neither in crude sap with the electron microscope nor in any other way. However, infectivity could easily be demonstrated in transmission tests with the greenhouse whitefly,Trialeurodes vaporariorum. Attempts to transmit the pathogen inLapsana communis withAleurodes proletella failed. The pathogen could also be transmitted by grafting inNicotiana glutinosa. In addition to the 6 species that were found naturally infected, 15 other species (belonging to 7 families) out of 27 tested were susceptible. All of these but 2 reacted with characteristic symptoms. The pathogen is similar to if not identical with beet pseudo-yellows ‘virus’ first described in California and later also reported in France, Italy and Tasmania. It may be of much wider distribution and of considerable yet incompletely assessed economic importance. Its nature remains obscure.  相似文献   

8.
Quantitative PCR revealed that Tomato chlorotic dwarf viroid (TCDVd) was present in substantial amounts in viroid-infected tomato flowers. Healthy tomato plants were arranged in two different glasshouses, and plants were mechanically inoculated with TCDVd. Bumblebees (Bombus ignitus) were then introduced into the glasshouses to reveal whether the viroid was transmitted from infected source plants to neighbouring healthy plants. TCDVd infection was found in neighbouring tomato plants more than 1 month after the introduction of the bees, some of which expressed symptoms, in both glasshouses. Thus, bumblebees transmitted TCDVd from tomato to tomato by pollination activities.  相似文献   

9.
Potato spindle tuber viroid (PSTVd) has been recently found in many solanaceous ornamental plant species. This study reports on the effectiveness of mechanical transmission between Brugmansia suaveolens, Solanum jasminoides, potato and tomato. Inoculation with ‘infected’ plant sap diluted in water, rubbing with contaminated finger tips and cutting with contaminated razor blades all resulted in transmission of PSTVd. Temperature, plant species and source of inoculum were found to be critical factors. An average temperature of 15°C only resulted in a few infections, whereas transmission at 20 and 25°C was more successful. Tomatoes were more susceptible to PSTVd than B. suaveolens, S. jasminoides and potatoes. Furthermore, S. jasminoides was a better source of inoculum than B. suaveolens. No transmission was obtained after repeated addition of inocula to tomato roots. These results indicate that PSTVd can be transmitted between plant species in practice by crop handling.  相似文献   

10.
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11.
Experiments were carried out to investigate whether Potato spindle tuber viroid (PSTVd) can be transmitted intra- and inter-species from infected Solanum jasminoides to non-infected S. jasminoides and S. esculentum and from infected Brugmansia sp. to S. esculentum by Frankliniella occidentalis and Thrips tabaci by leaf sucking. The F. occidentalis experiments also included feeding on pollen prior to feeding on PSTVd-infected leaf. No thrips-mediated transmission of PSTVd was recorded. The possibility of PSTVd transmission by Apis mellifera and Bombus terrestris during their feeding/pollinating activities within ornamentals and from ornamentals to S. esculentum was included, and no bee-mediated transmission was recorded.  相似文献   

12.
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13.
Nicandra physaloides, a common weed in South America, was found to be infected by an isolate of Tomato severe rugose virus (ToSRV), a bipartite begomovirus. The plants developed severe yellow rugose mosaic and were collected in São Paulo State, Brazil. This isolate of ToSRV was transmitted by Bemisia tabaci B biotype from infected plants of N. physaloides to healthy plants of N. physaloides and tomato in a glasshouse. This is the first report of natural infection of N. physaloides by ToSRV in Brazil.  相似文献   

14.
In situ hybridization was used to analyze the distribution pattern of Tomato chlorotic dwarf viroid (TCDVd) in floral organs of tomato plants. Following TCDVd invasion of floral organs, it became localized only in sepals at an early developmental stage, then reached other floral organs at the flower opening stage, with the exception of part of the placenta and ovules. When distribution of TCDVd was compared with that of Potato spindle tuber viroid (PSTVd), TCDVd was not detected in the outer integument around the embryo sac even though PSTVd was able to invade there, suggesting that such specific distribution might reflect the frequent occurrence of viroid disease on crops caused by PSTVd-seed transmission.  相似文献   

15.
In Belgium pospiviroids are routinely detected in various hosts. The most frequently found pospiviroids are: Citrus exocortis viroid (CEVd), Chrysanthemum stunt viroid (CSVd), Potato spindle tuber viroid (PSTVd), Tomato apical stunt viroid (TASVd) and Tomato chlorotic dwarf viroid (TCDVd). Apart from the high incidence of pospiviroids in latently-infected ornamentals, viroids have also been found in plants where they cause disease: PSTVd and TCDVd in tomatoes and CSVd in chrysanthemum. In order to gain more epidemiological data on these infections, this study has conducted phylogenetic analyses of Belgian isolates for each of these five pospiviroid species. PSTVd and CEVd-isolates show a clustering depending on host plant identity. This was not observed for TCDVd and TASVd. A very high degree of sequence similarity was noticeable for CSVd-isolates from various hosts. During the past decade, PSTVd and CSVd-infected mother plants have been systematically eradicated in Belgium after positive detection results, also when found in symptomless plants, leading to a decreased trend of these quarantine pests in the past few years. However, other non-quarantine pospiviroid species are still ubiquitously present in many ornamentals. Since these pospiviroids can be equally harmful to crops as the two quarantine pests PSTVd and CSVd, there is still a risk that transmission occurs from symptomless-infected ornamental plants to economically important crops in Belgium such as tomato, pepper and chrysanthemum.  相似文献   

16.
Journal of General Plant Pathology - Severe infection of the tomato cultivar ‘Rutgers’ with potato spindle tuber viroid (PSTVd) variants resulted in systemic stunting, leaf...  相似文献   

17.
Tomato chlorotic dwarf viroid (TCDVd) manually inoculated to transgenic (cv.‘Desiree’) potato plants containing antimicrobial cationic peptides failed to develop symptoms in above ground plant parts, but infected tubers were symptomatic. Plants from the infected tubers (second generation plants) emerged as either severely stunted (bushy stunt isolate, BSI) or tall and symptomless. Molecular characterization of BSI isolates showed TCDVd sequence variants 95 to 98% identical to TCDVd sequences from the database, while a viroid variant identical to TCDVd type isolate (acc # AF162131) was cloned from symptomless plants. The TCDVd BSI variants had novel U165C, GU177-178AA, and UCAC181-184CUUU nucleotide substitutions in the terminal right (TR) domain of the viroid molecule. The cloned viroid cDNAs of the BSI were infectious to experimental (cv. ‘Sheyenne’) tomato plants causing stunted plants with profuse auxiliary shoots. Visual evaluation of the susceptibility of the BSI to 18 potato and 21 tomato cultivars revealed severe symptoms in most cultivars of both species. The progeny variants accumulating in each potato and tomato cultivar exhibited the same novel TR domain in most cultivars, with only a slight variation in a few. The severity of the stunting symptoms induced by TCDVd from BSI isolates in both potato and tomato cultivars has not been noted previously with other TCDVd isolates and, as such, it is proposed that this new isolate be recognized as a distinct genotype. Emergence of this type of sequence variant in commercial fields or commercial tomato greenhouses could potentially cause relevant losses in both crops.  相似文献   

18.
A 303-nucleotide viroid was isolated from an apple tree (Malus × domestica, ‘Fuji’) cultivated in Japan. The viroid had 84.9% overall nucleotide sequence homology to Apple dimple fruit viroid (ADFVd), a member of Pospiviroidae, reported from Italy. This viroid differed from the Italian variant by 47 mutations (38 substitutions, six deletions and three insertions), and most of these mutations occurred on either side of the central conserved region. The leaves and branches of the infected trees did not have any disease symptoms, but the fruits were dimpled and yellow. The infected scions were top-grafted onto a healthy ‘Fuji’ apple tree, which tested positive for this viroid in a northern hybridization analysis, and yellow dimple fruits were produced in the second growing season. We propose that this viroid is a new variant of ADFVd and causes yellow dimple fruit formation in ‘Fuji’ apple trees.  相似文献   

19.
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20.
A viroid was detected for the first time in symptomless petunia plants (Petunia spp.) and identified as Tomato chlorotic dwarf viroid (TCDVd) based on an analysis of the complete genomic sequence. These petunia plants are a likely source of inoculum for tomato or potato plants because TCDVd induces severe symptoms on these plants. The genomic sequence of this petunia isolate from Japan shared 100 % identity with petunia isolates from the Netherlands and United Kingdom and a tomato isolate from Japan. Phylogenetic analysis showed that all petunia isolates and the tomato isolate from Japan formed a monophyletic clade.  相似文献   

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