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T. Kapari-Isaia A. Kyriakou L. Papayiannis D. Tsaltas S. Gregoriou I. Psaltis 《Plant pathology》2008,57(2):348-353
A new laboratory technique combining shoot-tip grafting in vitro and biological indexing on indicator plants was explored for the detection of citrus exocortis and related viroids. Τhree in vitro laboratory methods were used and compared with the classical biological method. With the classical in vivo method, diagnosis is based on the expression of symptoms on indicators 11–14 weeks after inoculation. In contrast, with the first in vitro method, microindexing in vitro of citron seedlings by graft inoculation, diagnosis was possible 12 days after inoculation; with the second method, microindexing in vitro of citron cuttings by graft inoculation, 20 days after inoculation; and with the third method, microindexing in vitro of citron cuttings by injection inoculation, 40 days after inoculation. Inoculated Etrog citron plantlets grown in vitro and tested by RT-PCR showed the same viroid content as the source plants. Of the three in vitro viroid indexing methods, microindexing on cuttings by grafting was easier and more reliable than microindexing either on seedlings or on cuttings by injection. 相似文献
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Four viroids were isolated in crops of tomato, eggplant, carrot and turnip. They were detected only after inoculation of 'Rutgers' tomato with nucleic acid extracts from field plants and were characterized as variants of citrus exocortis viroid (CEVd). The size of the variants ranged from 371 to 374 nucleotides and they contained nucleotide exchanges and insertions affecting all structural domains. Symptoms were induced in tomato and carrot whereas eggplant and turnip responded as symptomless carriers. As the samples came from an area where no citrus is grown, it appears that these viroids have a reproductive cycle independent of this crop, and perhaps involving wild plants or other vegetables. 相似文献
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Giorgio Gambino Beatriz Navarro Rosalina Vallania Ivana Gribaudo Francesco Di Serio 《European journal of plant pathology / European Foundation for Plant Pathology》2011,130(4):511-519
Indirect somatic embryogenesis is effective at eliminating the most important viruses affecting grapevines. Accordingly, this
technique was tested as a method for eradicating two widespread viroids, Grapevine yellow speckle viroid 1 (GYSVd-1) and Hop stunt viroid (HSVd), from four grapevine cultivars. Both viroids were detected by RT-PCR in grapevine floral explants used for initiating
embryogenic cultures, as well as in undifferentiated cells of embryogenic and non-embryogenic calli from anthers and ovaries.
In contrast, somatic embryos differentiated from these infected calli were viroid-free, and viroids were not detected in embryo-derived
plantlets even 3 years after their transfer to greenhouse conditions. A wider spatial distribution of HSVd than GYSVd-1 within
proliferating calli was revealed by in situ hybridization, whereas no hybridization signal was detected in the somatic embryos.
In addition, GYSVd-1 and HSVd were localised in the nucleus of infected cells, conclusively showing the nuclear accumulation
of representative members of Apscaviroid and Hostuviroid genera, which has been only an assumption so far. Somatic embryogenesis was compared to in vitro thermotherapy, a technique
routinely used for virus eradication. After thermotherapy, HSVd and GYSVd-1 were detected in all in vitro plantlets of the
cultivar Roussan, and in all lines analysed after 3 years of culture in greenhouse. The high efficiency with which somatic
embryogenesis may eliminate viroids and viruses from several infected grapevine cultivars, should allow the availability of
virus- and viroid-free material, which would be useful not only for sanitary selection but also for basic research on plant-virus
and plant-viroid interactions in grapevine. 相似文献
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A viroid was detected in Chrysanthemum plants showing symptotns of stunting in a commercial field in Brazil. Analysis by return polyacrylamide gel electrophoresis (R-PAGE) of the nucleic acid preparations of leaves and flowers revealed the presence of a nucleic acid of low molecular weight with mobility within the range of viroids. The viroid-like band was completely eliminated by ribonuclease treatment or alkaline hydrolysis. The Chrysanthemum viroid was readily transmissible to Chrysathemum , tomnato and Gynura , which suggests that it may be an isolate of chrysanthemum stunt viroid. 相似文献
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Oded Cohen Ozgur Batuman Yoni Moskowits Alexander Rozov Elisha Gootwine Munir Mawassi Moshe Bar-Joseph 《Phytoparasitica》2005,33(2):141-148
Mechanical inoculations with contaminating tools and propagation of infected budwood were considered the main causes for the
omnipresence of multiple viroid species among citrus and other Middle Eastern and Mediterranean fruit trees and grapevines.
However, neither means could explain viroid infections of wild trees — scattered on terrains inaccessible to humans — nor
the finding of similar viroids among graft-incompatible plants. Northern hybridization of RNA extracts made of scrapings from
the surfaces of goat (Capra hircus) horns that were rubbed against etrog (Citrus medica) stems infected with a citrus viroids complex, revealed accumulation of considerable amounts ofCitrus exocortis viroids (CEVd) andHop stunt viroids (HSVd). Experimental transmission of both CEVd and HSVd was obtained by rubbing healthy citrus plants with goat horns that
had been rubbed 24 h earlier on infected etrog stems. These results implicate goats as possible vectors of viroids. Transmissionvia goats could have facilitated the long-range spread of viroids among cultivated and wild plants andvice versa and also among graft-incompatible plants. 相似文献
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Vernière C Perrier X Dubois C Dubois A Botella L Chabrier C Bové JM Vila ND 《Phytopathology》2006,96(4):356-368
ABSTRACT Citrus exocortis viroid (CEVd), Citrus bent leaf viroid (CBLVd), a noncachexia variant of Hop stunt viroid (HSVd), Citrus viroid III (CVd-III), and Citrus viroid IV (CVd-IV) were co-inoculated as two-, three-, four-, and five-viroid mixtures to Clementine trees grafted on trifoliate orange to evaluate their effect on symptom expression, tree growth, and fruit yield. Most trees infected with CEVd-containing viroid mixtures developed exocortis scaling symptoms, as did CEVd alone, whereas most trees infected with HSVd- or CVd-IV-containing mixtures developed bark-cracking symptoms. Trees infected with mixtures containing both CEVd and CVd-IV revealed the existence of antagonism between these two viroids in terms of the expected bark-scaling and cracking symptoms. Synergistic interactions also were identified in trees infected with certain viroid combinations that, in spite of lacking CEVd, expressed exocortis-like scaling symptoms. Viroid interactions also affected the expected response of trees in terms of vegetative growth and fruit yield. Trees infected with viroid combinations containing CEVd or CVd-III were smaller and produced less fruit than trees infected with mixtures not containing these viroids. Viroid interactions on scion circumference and cumulative fruit yield, in terms of additivity of their effects, were statistically confirmed using a factorial analysis of variance model with two mean estimation approaches. In single-viroid infections, CEVd, CVd-III, and, to a lesser extent, CBLVd consistently and significantly reduced tree size and fruit yield. Conversely, HSVd and CVd-IV slightly increased fruit yield and reduced scion circumference. Rare and not consistent significant interactions were detected with the five-, four-, and three-viroid combinations. Antagonistic interactions between CEVd and CVd-III or CBLVd and CVd-III were revealed over the years with consistent significance. The antagonistic interaction between CEVd and CVd-IV was highly significant over the years when additional viroids were present; however, this antagonism appeared much later in the case of an exclusive interaction. HSVd and CVd-IV showed a consistent and significant synergistic interaction on yield only when both viroids were exclusively present. These results demonstrate antagonistic or synergistic relationships between citrus viroids depending on the viroid mixtures present in the host. 相似文献
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In studies to identify genotypes resistant to infection with citrus viroids, Eremocitrus glauca and Microcitrus australis were selected because their evolution in their habitat in Australia and New Guinea may have led to the selection of unusual traits. The movement and accumulation of Citrus exocortis viroid (CEVd), Hop stunt viroid, Citrus bent leaf viroid, Citrus dwarfing viroid, Citrus bark cracking viroid and Citrus viroid V (CVd‐V) in self‐rooted as well as in graft‐ propagated E. glauca and M. australis plants was assessed by northern hybridization, RT‐PCR and by topworking to the sensitive selection 861‐S1 of Etrog citron. In both plant species the inoculated viroids were undetectable unless these plants were grafted to a susceptible Citrus partner, the rough lemon rootstock and/or the topworked Etrog citron, which acted as viroid sources. The results obtained indicate that M. australis and in particular E. glauca are poor viroid hosts in which viroid replication/accumulation does not occur or is extremely inefficient. However, viroid downward and upward movement to grafted Citrus partners in which viroid replication and accumulation occurs efficiently was not impaired. Eremocitrus glauca and M. australis showed differences regarding their properties as viroid hosts, but for both species CEVd seemed to have the lowest affinity among the viroid species tested and CVd‐V the highest. Even though E. glauca and M. australis do not appear to be truly resistant to viroid infection, they are interesting genotypes for further characterization of the mechanisms involved in viroid infection. 相似文献
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More than 600 Prunus samples were examined by using a nonradioactive digoxigenin-labelled RNA probe specific for hop stunt viroid (HSVd). Prunus salicina and Prunus armeniaca appeared to be better hosts than Prunus persica . The weak viroid concentration in flowers and young leaves of peach trees growing in the field did not permit its detection in such samples. The diagnosis was more reliable (about 85%) with bark and leaves aged 4 months and more, from regrowths of GF 305 peach seedlings inoculated and kept in the greenhouse. Detection of HSVd in leaves and bark of apricot and Japanese plum plants aged 3 months or more also proved reliable (about 80% and 90%, respectively). HSVd could be transmitted in apricot, peach and plum nucleic acid preparations to GF 305 peach seedlings by repeated stem slashing, and to cherries ( Prunus avium and Prunus serrulata ) by approach grafting with an infected P. salicina source. The viroid was eliminated from 18% of the clones obtained after thermotherapy.
In the course of this study, 25 selected Prunus accessions suspected to be infected by unusual diseases were analysed by hybridization with a HSVd-specific probe and by indexing on GF 305 peach seedlings in the greenhouse. Fifteen of these accessions were found to be infected by HSVd, 19 induced reddish marbling, and four induced small blackish spots on the leaves aged about 4 months. Repeated assays showed that these foliar symptoms were not caused by the viroid. Peach red marbling (PRMa) has not been associated with any known virus and seems to be caused by an infectious agent not yet described. That could also be the case with the agent of peach sooty ringspot (PSRS). PRMa and PSRS symptoms were reproduced by grafting and indexing, and their causal agents eliminated by thermotherapy in a significant fraction of the treated plants. They behave like viral agents and can infect the different Prunus species studied. 相似文献
In the course of this study, 25 selected Prunus accessions suspected to be infected by unusual diseases were analysed by hybridization with a HSVd-specific probe and by indexing on GF 305 peach seedlings in the greenhouse. Fifteen of these accessions were found to be infected by HSVd, 19 induced reddish marbling, and four induced small blackish spots on the leaves aged about 4 months. Repeated assays showed that these foliar symptoms were not caused by the viroid. Peach red marbling (PRMa) has not been associated with any known virus and seems to be caused by an infectious agent not yet described. That could also be the case with the agent of peach sooty ringspot (PSRS). PRMa and PSRS symptoms were reproduced by grafting and indexing, and their causal agents eliminated by thermotherapy in a significant fraction of the treated plants. They behave like viral agents and can infect the different Prunus species studied. 相似文献
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Suspension depletion approach for exemption of infected Solanum jasminoides cells from pospiviroids 
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下载免费PDF全文 I. Digel V. Wehlitz P. Kayser A. Figiel‐Lange R. Bassam F. von Rundstedt 《Plant pathology》2018,67(2):358-365
Despite numerous studies, viroid elimination from infected plants remains a very challenging task. This study introduces for the first time a novel ‘suspension depletion’ approach for exemption of Solanum jasminoides plants from viroids. The proposed method implies initial establishment of suspension cultures of the infected plant cells. The suspended cells were then physically treated (mild thermotherapy, 33 °C), which presumably delayed the replication of the viroid. The viroid concentration in the treated biomass was monitored weekly using pospiviroid‐specific PCR. After 10–12 weeks of continuous treatment, a sufficient decrease in viroid concentration was observed such that the infection became undetectable by PCR. The treated single cells then gave rise to microcolonies on a solid culture medium and the obtained viroid‐negative clones were further promoted to regenerate into viroid‐free plants. Three years of accumulated experimental data suggests feasibility, broad applicability, and good efficacy of the proposed approach. 相似文献
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The polyacrylamide gel electrophoresis (PAGE) test of Morris & Smith (1977) was evaluated for detection of potato spindle tuber viroid (PSTV) in breeding material. Number, density and mobility of nucleic acid bands in the electropherograms were influenced by genotype and growing temperature. So direct testing of genotypes was not reliable. After an intermediate viroid multiplication in tomato host plants at about 30oC and high irradiance, PSTV was reliably detectable with PAGE in inocula of potato samples of diverse origin. A 4-week incubation period proved to be suitable for inocula with low and high concentrations of a mild strain of PSTV (m-PSTV) as well as a severe strain of PSTV (s-PSTV). If incidence of PSTV is expected to be low, testing can be speeded up by bulking samples. With the combined tomato-intermediate/ PAGE assay, one m-PSTV or one s-PSTV infected leaf disk in 200 healthy ones was consistently detectable. Occasionally gels with a nucleic acid band of about the same relative mobility as the viroid band were found. Evidence that these bands were not caused by viroid is presented. A procedure to resolve such questionable test results is described. Infectivity of s-PSTV was higher than that of m-PSTV. Concentration of viroids in the inoculum influenced appearance of mild or severe symptoms and the rate of symptom production. 相似文献
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Yosuke Matsushita Tomio Usugi Shinya Tsuda 《European journal of plant pathology / European Foundation for Plant Pathology》2009,124(2):349-352
We characterised the host range and physical properties of Tomato chlorotic dwarf viroid. Among the 46 plant species inoculated with the viroid, two in the family Compositae and 23 in the family Solanaceae were
found to be systemic hosts. The viroids in the crude sap from diseased tomato plants were thermally inactivated by heating
to 100°C for at least 40 min. These viroids also lost their infectivity when diluted in phosphate buffer to at least 10−6, or after 3 days of incubation at room temperature. However, the infectivity of the viroids in dried crude sap from the plants
persisted throughout the 50-day test period. 相似文献
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The fast growth of the human population forces us to produce more food, but higher crop production also leads to the fast spread of diseases. Plant pathology deploys a wide range of methods that do not provide an adequate solution to all disease losses. In the case of viroids, therapeutic means of control are not available; therefore control strategies are more focused on the development of reliable detection methods to quickly exclude the infected plant material. Although viroids are the smallest and simplest plant pathogens, their identification and detection is not straightforward. Each viroid–host combination is specific, and for reliable identification, all steps from sampling to final detection must be performed accurately. In this review, several methods for viroid detection in various host plants are discussed, including their advantages and disadvantages. Even though relatively new molecular methods enable fast and sensitive detection of viroids, a combination of different methods gives the most reliable identification. Techniques based on nucleic acids may be the future for viroid detection but they still cannot replace biological indexing, which is usually essential in epidemiological and aetiological studies. 相似文献
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Host range and symptomatology of a graft-transmissible pathogen causing bud union crease of citrus on trifoliate rootstocks 总被引：2，自引：0，他引：2
L. Galipienso L. Navarro J.F. Ballester-Olmos J.A. Pina P. Moreno & J. Guerri 《Plant pathology》2000,49(2):308-314
A graft-transmissible pathogen causing bud union crease of Nagami kumquat SRA–153 on Troyer citrange was characterized for host range and symptomatology. Buds of Marsh grapefruit, Nules clementine, Eureka lemon and Pineapple sweet orange preinoculated with kumquat SRA–153 were propagated on citrange rootstocks. Some plants of Nules clementine and Eureka lemon had developed bud union crease six months after propagation, whereas all Marsh grapefruit and Pineapple sweet orange plants still showed normal bud union after one year. On indexing these preinoculated species, Nules clementine and Eureka lemon caused vein clearing in Pineapple sweet orange and Dweet tangor, chlorotic blotching in Dweet tangor and stem pitting in Etrog citron, whereas Marsh grapefruit and Pineapple sweet orange caused only chlorotic blotching in Dweet tangor and stem pitting in Etrog citron. Following shoot-tip grafting in vitro of kumquat SRA–153, kumquats 38–1 and 497–2 obtained from it caused chlorotic blotching in Dweet tangor and stem pitting in Etrog citron, but not vein clearing in Pineapple sweet orange and Dweet tangor or bud union crease when propagated on citrange. These results suggest the presence of at least two pathogens or pathogen strains in kumquat SRA–153 and the elimination of one of them after shoot-tip grafting in vitro or inoculation on Marsh grapefruit or Pineapple sweet orange. They also indicate that the pathogens in kumquat SRA–153 can be detected by indexing on Dweet tangor or Etrog citron. 相似文献
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苹果锈果病(ASSD)类病毒的侵染性 总被引：1，自引：0，他引：1
用机械接种的方法研究了苹果锈果病类病毒(ASSV)的侵染性.在嫁接时将接种原滴于砧木和接穗的切面上,用针刺切面,然后观察症状表现,所有接穗都取自同一株健康“国光”.用半提纯的ASSD—RNA—1和ASSD—RNA—2接种的,成活的3株中有2株发病;用提纯的ASSD—RNA—1和ASSD—RNA—2接种的,成活的3株中有1株发病;用病组织的澄清汁液接种的,成活的4株中有1株发病;用缓冲液模拟接种的健康对照成活的5株均未发病.发病苗木的症状为叶片卷曲,随后叶片从叶柄处断裂.从发病的,不发病的及健康对照的苗木茎部提取核酸,用双向及两次聚丙烯酰胺凝胶电泳分析,表现症状的4株均测出了ASSD—RNA—1,未发病的及用缓冲液模拟接种的健康对照均未检测出类病毒核酸带.结果表明ASSD—RNA—1可通过机械传播,为苹果锈果病的类病毒病原提供了又一次证据,也表明ASSD—RNA—1代表了能独立复制的苹果锈病类病毒. 相似文献