The sequence of a viroid from grapevine closely related to. Get a printable copy pdf file of the complete article 524k, or click on a page image below to browse page by page. Multiplex detection, distribution, and genetic diversity of hop stunt viroid and citrus exocortis viroid infecting citrus in taiwan. Documents about citrus exocortis viroid cevd00 eppo global database. Iresine viroid irvd, citrus exocortis viroid cevd, and chrysanthemum stunt viroid csvd. Currently, 7 citrus viroid species are recognized including citrus bent leaf viroid cblvd, hop stunt viroid hsvd, citrus dwarfing viroid cdvd, citrus bark cracking viroid cbcvd, citrus viroid v cvdv, citrus viroid vi cvdvi and citrus exocortis viroid cevd. A mutual titerenhancing relationship and similar localization patterns between citrus exocortis viroid and hop stunt viroid coinfecting two citrus cultivars zeitschrift. It also examines the diseases associated with different plant species. Infectivity was dependent on the site of the viroid molecule used for cloning and the orientation of the cdna insert. Molecular cloning, secondary structure, and phylogeny of.
Potato spindle tuber viroid in solanum laxum synonym s. The distributions and infection rates of two viroids have not been investigated since the two diseases were presented decades ago. Monomeric cdna clones of citrus exocortis viroid cev were constructed in the plasmid vector psp64 and the infectivity of the clones plus in vitrosynthesized rna transcripts determined by inoculation onto tomato seedlings. Viroids were identified and characterized by biological indexing in etrog citron, northernblot hybridization, rtpcr, cloning and complete sequencing of the rna genomes. We developed a multiplex reverse transcription polymerase chain reaction rtpcr to detect six citrus viroids. It provides a single source of information on the properties of viroids, the economic impact of viroid diseases and methods for their detection and control. The rootstocks of trifoliated orange, rangpur lime, and swingle citrumelo are particularly sensitive to the disease. Citrus exocortis viroid causes ribosomal stress in tomato plants. It has a wide natural and experimental host range, mostly composed of symptomless viroidhost combinations. The cracks are usually longitudinal, with the bark remaining alive and additional cracks forming as.
Viroid species associated with the barkcracking phenotype. Citrus exocortis viroid rtpcr detection kit norgens citrus exocortis viroid cevd rtpcr detection kit constituents a complete, readytouse system for the isolation and detection of cevd using endpoint rtpcr. The alternative herbaceous host, cucumber cucumis sativus cv. Citrus exocortis viroid causes ribosomal stress in tomato.
Peach latent mosaic viroid plmvd was the d168 isolate causing symptoms in gf305 peach seedlings, prunuspersica l. Citrus exocortis viroid induces in tomato plants lycopersicon esculentum synthesis and accumulation of a pathogenesisrelated protein p69 previously reported to be a proteinase vera p, conejero v 1988 plant physiol 87. Citrus exocortis viroid cevd was the first citrus viroid described roistacher, 1991. Salicylic acid is involved in the basal resistance of tomato. A viroid present in very low titres was isolated from symptomless field broad bean plants. Primers specific to viroid species, based on partial nucleotide sequences of the viroids, were used. Abouelfotoh agriculture research centre, giza, egypt summary the first identification of citrus exocortis viroid cevd in egypt was carried out by. Nucleotide sequence analysis of polymerase chain reaction pcramplified pospiviroidrelated fragments in several symptomless ornamental plants indicated the presence of three distinct viroid species. In vivo generated citrus exocortis viroid progeny variants display a range of phenotypes with altered levels of replication, systemic accumulation and pathogenicity. Two citrus viroids, citrus exocortis viroid cevd and hop stunt viroid hsvd, have been reported and become potential threats to the citrus industry in taiwan. Natural infections of tomato by citrus exocortis viroid, columnea. Citrus exocortis viroid cevd is the causal agent of citrus exocortis and affects trifoliate orange poncirus trifoliata l. Salicylic acid is involved in the basal resistance of.
Citrus exocortis viroid cevd exists as populations of heterogeneous variants in infected hosts. Eleven new sequence variants of citrus exocortis viroid and. Download table nucleotide diversity within and between citrus exocortis viroid cevd populations from publication. Comparative analysis of techniques for detection of.
Citrus exocortis viroid cevd causes stunting of plants, shelling of bark may result in little yield loss may be useful to promote dwarfing for agronomic advantage transmitted through stock, graft control by removal of infected plants, detection. Replication of in vitro constructed viroid mutants. Pcr was used for the detection of citrus exocortis viroid cevd in total nucleic acids from infected citrus indicator hosts or directly from field trees. Fulllength doublestranded cdna was prepared from purified circular rna of two new australian field isolates of citrus exocortis viroid cev using. Infection of several hosts resulted in a change in the composition of the viroid population. Shortly thereafter, sequences of several other viroids, including those of citrus exocortis cevd, chrysanthemum stunt csvd and avocado sunblotch asbvd appeared, and the knowledge of their molecular prop. Apple scar skin viroid assvd was an isolate from apple, maluspumila mill. Prokaryoteassociated grafttransmissible diseases such as huanglongbing, stubborn, witches broom of lime, and citrus. Citrus exocortis viroid, potato spindle tuber viroid and tomato chlorotic dwarf viroid. The properties of and relationships between these two members of the citrus viroid ii group and the definition of the exocortis and cachexia xyloporosis diseases are presented.
Pdf global transcriptomic analysis reveals insights into. Exocortis, sometimes referred to as scalybutt, was a major disease of australian citrus trees on trifoliate orange rootstock in the 1940s and 50s, but is now rarely seen because of the use of pathogenfree budwood from the auscitrus budwood scheme. Citrus exocortis viroid cevd, hop stunt viroid, citrus bent leaf viroid, citrus dwarfing viroid, citrus bark cracking viroid and citrus viroid v remained phloem. Construction and application of infectious citrus viroids. Citrus exocortis viroid, potato spindle tuber viroid and tomato chlorotic dwarf viroid were identified. The kit first allows for the isolation of total rna, including viroid rna, from plant tissues using a convenient spincolumn. Pdf characterization of a citrus exocortis viroid variant in yellow.
Here, the alterations caused by the citrus exocortis viroid cevd on the tomato translation machinery were studied as a new aspect of viroid pathogenesis. Citrus exocortis viroid, belonging to the genus pospiviroid of the family pospiviroidae, is the causal agent of the exocortis disease. It has a wide natural and experimental host range, mostly composed of symptomless viroid host combinations. By immunogoldtransmission electron microscopy, we have studied the distribution of this protein in thin sections of parenchymatous leaf tissue. Abdou plant pathology department, faculty of agriculture cairo university, egypt a. First report of pospiviroids infecting ornamental plants in australia. General information about citrus exocortis viroid cevd00.
Reverse transcription polymerase chain reaction rt. Surveys of impatiens and verbena species in local nurseries in fredericton, canada and verbena species in new delhi, india showed widespread infection of citrus exocortis viroid cevd in vegetativelypropagated and seedgrown plants. Potato spindle tuber viroid and tomato chlorotic dwarf viroid were identi. The sequence of a viroid from grapevine closely related to severe isolates of citrus exocortis viroid. It has also been reported to affect tomato, grapevine, and certain ornamental species.
Pdf viroids are small, circular rna pathogens, which infect several crop plants and can cause diseases of economic importance. Pdf first report of potato spindle tuber and citrus exocortis viroids. The presence of viroids in the ribosomal fractions of infected tomato plants was detected. The distributions and infection rates of two viroids have not been investigated since the two diseases were presented decades a.
This work presents information on viroids and viroid diseases. Rootstocks affected include citrus macrophylla, some mandarins, and sweet lime. Sequence variants from field isolates of citrus exocortis viroid cev that cause either mild or severe symptoms on tomato plants have previously been classified into two groups, a and b. Citrus exocortis viroid cevd00overview eppo global database. Viroids as companions of a professional career ncbi. Citrus exocortis viroid an overview sciencedirect topics.
Viroid species identified in citrus induce a range of symptoms in this host as well as in non citrus hosts. Construction and application of infectious citrus viroids for. Viroid systemic spread involves celltocell movement from initially infected cells via plasmodesmata, longdistance movement within the phloem and again celltocell movement to invade distal tissues including the mesophyll. Citrus exocortis viroid transmission through commercially.
Citrus exocortis viroid cevd, can infect all varieties of citrus but is symptomless in most. Cevd is associated with bark shelling on trees grown on p. Viroids are infectious molecules of rna garnsey and jones, 1967. Citrus exocortis is a disease of citrus plants, caused by the citrus exocortis viroid cevd. It was identified as a variant of citrus exocortis viroid in the t 2, v and c domains. In this study, we investigated the relationship between the two viroids at macroscopic and microscopic levels. In vivo generated cevd progeny variants cevdpvs populations from citrus protoplasts, seedlings and mature plants,followinginoculation withtranscripts ofasinglecevd cdnaclonewildtype,wt,werestudied. Citrus exocortis viroid cevg taxonomy navigation citrus exocortis viroid. Rapid in vitro microindexing of viroids in citrus kapari. We do not use these to store personal information about you. In citrus, exocortis is an important viroid disease of the commonly used rootstock, poncirus trifoliata and is characterized by bark scaling, leaf epinasty, yellow blotching of twigs, and severe tree stunting singh et al.
These two viroids have been classified by bioassay reactions as the causal agents of two distinct types of citrus disease, an exocortislike syndrome and cachexia. Pdf first report of pospiviroids infecting ornamental. Citrus exocortis, also reported as scalybutt, was described as a bark scaling disorder affecting the rootstock of trees grafted on the trifoliate. Poncirus trifoliata is the main rootstock, so citrus viroids are a limiting factor for further citriculture development. Detection of multiple infections of citrus exocortis viroid. Citrus exocortis viroid cevd00documents eppo global database. In cyprus, a study showed that citrus exocortis viroid and other citrus viroids are widespread kyriakou, 1992. Citrus exocortis viroid cevd was a citrus isolate inducing severe symptoms in citrus medica l. Citrus exocortis viroid cevd, citrus bent leaf viroid cblvd, hop stunt viroid hsvd, citrus viroid iii cvdiii, citrus viroid iv cvdiv and citrus viroid os cvdos and apple stem grooving virus asgv, synonym. Jul 08, 2019 download table nucleotide diversity within and between citrus exocortis viroid cevd populations from publication. Immunogold localization of the citrus exocortis viroid.
Cevd is around 370 nucleotides in size and belongs to genus pospiviroid of family pospiviroidae. Natural infections of tomato by citrus exocortis viroid. A crucial question to be addressed is how accumulations of these two viroids affect each other in an infected plant. Citrus exocortis viroid cevd, the causal agent of the exocortis. The lack of sa accumulation in the cevd or tswvinfected nahg tomato plants led to an early and dramatic disease phenotype, as. Chunyi lin, mengling wu, tanglong shen, tinghsuan hung. General information about citrus exocortis viroid cevd00 this website uses cookies our website uses cookies to ensure that we give you the best possible online experience.
Nov 22, 2019 citrus exocortis viroid citrus exocortis. Global transcriptomic analysis reveals insights into the response of etrog citron citrus medica l. Phloem restriction of viroids in three citrus hosts is. Summary recovery of highly purified citrus cachexia viroid ccav was accomplished by serial elution following cf11 cellulose chromatography of a 2 mliclsoluble nucleic acid preparation. Viroid species identified in citrus induce a range of symptoms in this host as well as in noncitrus hosts. Citrus exocortis viroid, columnea latent viroid, potato naldc usda. Suyo, yielded greater quantities of the viroid than the highest yielding citrus host, citron citrus medica cv. In vivo generated citrus exocortis viroid progeny variants. In mainland china, only the presence of citrus exocortis viroid cevd has been reported from etrog citron indexing. Since the early 1970s when viruslike agents were considered as the cause of two diseases potato spindle tuber and citrus exocortis, their study and further characterization have been linked to the development and use of molecular biology tools.
Per cent sequence identity between the citrus exocortis viroid variant under. Like the isolates previously isolated from ornamental species, the isolates from. These groups differ primarily in two domains, p l and p r, of the proposed native structure. To determine viroid seed transmission, samples of eight varieties of impatiens and 11 varieties of verbena were obtained from four commercial sources.
Continuing to use this website means you agree to our use of cookies. The genetic diversities and evolutionary relationships of two viroids also remain unclear in the mix. Because of their rna nature, many studies have focused on the involvement of viroids in rnamediated gene silencing as being their pathogenesis mechanism. Two citrus viroids, citrus exocortis viroid cevd and hop stunt viroid hsvd, have been reported and become potential threats to the citrus. Plants of 32 species of citrus and related genera grafted on rough lemon rootstock were inoculated with an artificial mixture of citrus viroids containing citrus exocortis viroid, citrus viroid. Identification of a new viroid as the putative causal. Tomato plants expressing the nahg transgene, which prevents accumulation of endogenous salicylic acid sa, were used to study the importance of the sa signalling pathway in basal defence against citrus exocortis viroid cevd or tomato spotted wilt virus tswv. It can cause stunted growth and reduced yields in affected plants. Virus and viroidfree healthy propagating material of citrus may be.
Another viroid that occurs commonly in florida is citrus viroid iii, which affects the same rootstocks as citrus exocortis viroid and causes stunting but no scaling. Citrus exocortis viroid cevd, hop stunt viroid hsvd and citrus dwarfing viroid cdvd were found in different combinations. Molecular understanding of viroid replication cycles and. Multiplex detection, distribution, and genetic diversity of. Multiplex detection, distribution, and genetic diversity of hop stunt viroid and citrus exocortis viroid infecting citrus in taiwan chunyi lin1, mengling wu2, tanglong shen1, hsinhung yeh3 and tinghsuan hung1 abstract background. Multiplex detection, distribution, and genetic diversity.
Using confocal laser scanning microscopy and transmission electron microscopy in conjunction with in situ hybridization, both citrus exocortis viroid cevd and cccvd were found in vascular tissues as well as in mesophyll cells bonfiglioli et al. Multiplex detection, distribution, and genetic diversity of hop stunt. A citrus exocortis viroid variant from broad bean vicia faba. Simultaneous detection of six citrus viroids and apple. Two citrus viroids, citrus exocortis viroid cevd and hop stunt viroid hsvd, have been reported and. However, when buds from citron with the severe strain of citrus exocortis viroid were grafted to citron containing the moderate strain, the severe strain became predominant, indicating no cross protection j. Direct nucleotide sequencing of citrus exocortis viroid cevd.
Infectivity and in vitro mutagenesis of monomeric cdna. Viruses free fulltext global transcriptomic analysis. Here, the alterations caused by the citrus exocortis viroid cevd on the tomato. Studies on citrus exocortis viroid cevd in egypt a. Citrus exocortis, known also as scalybutt, is caused by the citrus exocortis viroid cevd. Sep 17, 2015 citrus exocortis viroid cevd and hop stunt viroid hsvd are commonly found simultaneously infecting different citrus cultivars in taiwan.