Citrus Tristeza Virus Isolates of the Same Genotype Differ in Stem Pitting Severity in Grapefruit

Two isolates of the T68 genotype of citrus tristeza virus (CTV) were derived from a common source, GFMS12, by single aphid transmission. These isolates, named GFMS12-8 and GFMS12-1.3, induced stem pitting with differing severity in ‘Duncan’ grapefruit (Citrus × paradisi [Macfad.]). Full-genome sequencing of these isolates showed only minor nucleotide sequence differences totaling 45 polymorphisms. Numerous nucleotide changes, in relatively close proximity, were detected in the p33 open reading frame (ORF) and the leader protease domains of ORF1a. This is the first report of full-genome characterization of CTV isolates of a single genotype, derived from the same source, but showing differences in pathogenicity. The results demonstrate the development of intragenotype heterogeneity known to occur with single-stranded RNA viruses. Identification of genetic variability between isolates showing different pathogenicity will enable interrogation of specific genome regions for potential stem pitting determinants.

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Stem-Pitting Citrus tristeza virus Predominantly Transmitted by the Brown Citrus Aphid from Mixed Infections Containing Non-Stem-Pitting and Stem-Pitting Isolates

Plant Disease ◽

10.1094/pdis-10-10-0772 ◽

2011 ◽

Vol 95 (8) ◽

pp. 913-920 ◽

Cited By ~ 5

Author(s):

R. H. Brlansky ◽

Avijit Roy ◽

V. D. Damsteegt

Keyword(s):

Citrus Tristeza Virus ◽

Fruit Size ◽

Haplotype Diversity ◽

Aphid Transmission ◽

Single Strand Conformation Polymorphism ◽

Mixed Infections ◽

Tristeza Virus ◽

Stem Pitting ◽

Citrus Spp ◽

Citrus Tristeza

Citrus tristeza virus (CTV) is a phloem-limited Closterovirus that produces a variety of symptoms in various Citrus spp. One of these symptoms is stem pitting (SP). SP does not occur in all Citrus spp. but when it does it may cause low tree vigor, decline, and an economic reduction in fruit size and yield. Historically, the first appearance of CTV-SP in a citrus area often occurs after the introduction of the most efficient CTV vector, the brown citrus aphid (BCA), Toxoptera citricida. Hypotheses for this association range from the introduction of these strains in new planting materials to the increased ability of BCA to transmit SP strains from existing CTV sources. It is known that CTV often exists as a complex of isolates or subisolates. Single and multiple BCA transmissions have been used to separate different genotypes or strains of CTV from mixed CTV infected plants. This study was initiated to determine what the BCA transmits when an exotic severe SP CTV isolate B12 from Brazil or B408 from Dominican Republic are mixed with a non-SP (NSP) isolate, FS627 from Florida. Biological and molecular data was generated from grafted mixtures of these isolates and their aphid-transmitted subisolates. Single-strand conformation polymorphism patterns of the 5′ terminal region of open reading frame (ORF) 1a, the overlapping region of ORF1b and ORF2, and the major coat protein gene region of NSP and SP CTV-grafted plants remained unchanged but the patterns of doubly inoculated plants varied. The haplotype diversity within SP isolates B12, B408, and mixtures of NSP and SP isolates (FS627/B12 and FS627/B408) and aphid-transmitted subisolates from doubly inoculated plants was determined by analysis of the haplotype nucleotide sequences. Aphid transmission experiments, symptoms, and molecular analyses showed that SP-CTV was more frequently transmitted with or without NSP-CTV from mixed infections.

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Citrus Tristeza Virus: Molecular Approaches to Cross Protection

10.32747/1994.7570551.bard ◽

1994 ◽

Author(s):

William O. Dawson ◽

Moshe Bar-Joseph ◽

Charles L. Niblett ◽

Ron Gafny ◽

Richard F. Lee ◽

...

Keyword(s):

Citrus Tristeza Virus ◽

Complex Structure ◽

Genetic System ◽

Aphid Transmission ◽

Open Reading Frames ◽

Molecular Approaches ◽

Defective Rnas ◽

Tristeza Virus ◽

Stem Pitting ◽

Citrus Tristeza

Citrus tristeza virus (CTV) has the largest genomes among RNA viruses of plants. The 19,296-nt CTV genome codes for eleven open reading frames (ORFs) and can produce at least 19 protein products ranging in size from 6 to 401 kDa. The complex biology of CTV results in an unusual composition of CTV-specific RNAs in infected plants which includes multiple defective RNAs and mixed infections. The complex structure of CTV populations poses special problems for diagnosis, strain differentiation, and studies of pathogenesis. A manipulatable genetic system with the full-length cDNA copy of the CTV genome has been created which allows direct studies of various aspects of the CTV biology and pathology. This genetic system is being used to identify determinants of the decline and stem-pitting disease syndromes, as well as determinants responsible for aphid transmission.

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Population Dynamics of a Florida Citrus tristeza virus Isolate and Aphid-Transmitted Subisolates: Identification of Three Genotypic Groups and Recombinants After Aphid Transmission

Phytopathology ◽

10.1094/phyto-99-11-1297 ◽

2009 ◽

Vol 99 (11) ◽

pp. 1297-1306 ◽

Cited By ~ 28

Author(s):

Avijit Roy ◽

R. H. Brlansky

Keyword(s):

Population Dynamics ◽

Citrus Tristeza Virus ◽

Pcr Amplification ◽

Aphid Transmission ◽

Rt Pcr ◽

Reading Frame ◽

Florida Citrus ◽

Tristeza Virus ◽

Overlapping Region ◽

Citrus Tristeza

Tristeza is an important citrus disease affecting the viability and productivity of citrus worldwide. The causal agent, Citrus tristeza virus (CTV), usually occurs as a mixture of genotypes in nature, with one of the genotypes often dominating the population. CTV has a monopartite, positive-sense RNA genome of ≈19.3 kb and exhibits over 30% diversity in the 5′ half and less than 10% in the 3′ half among different genotypes. A Florida CTV isolate, FS627, was selected for this study. Isolate FS627 was analyzed by reverse-transcription polymerase chain reaction (RT-PCR) using primers to three regions: 788-bp region in the 5′ (697 to 1,484 nucleotides), open reading frame (ORF)1a, 696 or 718 bp from the overlapping region of the RdRp (ORF1b) and p33 (ORF2) gene, and a 672-bp major coat protein gene (ORF7) in the 3′ end of the CTV genome. The presence of T36, T30, and VT genotypes in isolate FS627 was confirmed utilizing the genotype specific overlapping region of RdRp primer pairs for RT-PCR amplification followed by cloning and sequence analysis. Analysis of single-strand conformational polymorphisms and sequences of RT-PCR-amplified products of the above regions were used to determine the presence of genotypes in both the parent and aphid-transmitted (AT) subisolates. Although the parent isolate had T36 as the major genotype, T30 was the major genotype in most of the AT subisolates. Some intermediate genotypes were detected that differed from the parental or AT subisolates. These intermediate genotypes were considered to be recombinants of the T30 and T36 genotypes and also were observed in the second level of AT subisolates generated from the of first-level AT subisolates of CTV-FS627. This work provides advance information on the population dynamics in CTV mixtures and the generation of virus recombinants after aphid transmission.

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Production of Antibodies to Citrus Tristeza Virus in Transgenic Citrus

10.32747/1995.7613018.bard ◽

1995 ◽

Author(s):

Richard Lee ◽

Moshe Bar-Joseph ◽

K.S. Derrick ◽

Aliza Vardi ◽

Roland Brlansky ◽

...

Keyword(s):

Citrus Tristeza Virus ◽

Virus Disease ◽

Biological Activities ◽

Cp Gene ◽

Single Domain Antibodies ◽

Tristeza Virus ◽

Stem Pitting ◽

Citrus Tristeza

Citrus tristeza virus (CTV) is the most important virus disease of citrus in the world. CTV causes death of trees on sour orange rootstock and/or stem pitting of scions regardless of rootstock which results in trees of low vigor, reduced yield with reduction in size and quality of fruit. The purpose of this project was to produce monoclonal antibodies (MABs) to CTV coat protein (CP), develop single domain antibodies (dAbs) or Fab fragments which neutralize the infection by binding to the virus, and to produce transformed plants which express the dAbs. The objectives of this research have been met and putative transgenic tobacco and citrus plants have been developed. These putative transgenic plants are presently undergoing evaluation to determine the level of dAbs expression and to determine their resistance to CTV. Additionally, the CTV genome has been sequenced and the CP gene of several biologically characterized CTV strains molecular characterized. This has indicated a correlation between CP sequence homology and biological activity, and the finding of DI RNAs associated with some CTV strains. Several MABs have been produced which enable broad spectrum identification of CTV strains while other MABs enable differentiation between mild and severe strains. The use of selected MAbs and determination of the CP gene sequence has enabled predictions of biological activities of unknown CTV isolates. The epitopes of two MABs, one reacting selectively with severe CTV strains and the other reacting with all strains, have been characterized at the molecular level.

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Genetic Diversity and Phylogenetic Analysis of Citrus tristeza virus Isolates from Turkey

Advances in Virology ◽

10.1155/2019/7163747 ◽

2019 ◽

Vol 2019 ◽

pp. 1-11 ◽

Cited By ~ 1

Author(s):

Gözde Erkiş-Güngör ◽

Bayram Çevik

Keyword(s):

Phylogenetic Analysis ◽

Citrus Tristeza Virus ◽

Molecular Characteristics ◽

Cloning And Sequencing ◽

Phylogenetic Groups ◽

The 1960S ◽

Tristeza Virus ◽

Virus Isolates ◽

Stem Pitting ◽

Citrus Tristeza

The presence of Citrus tristeza virus (CTV) in Turkey has been known since the 1960s and the virus was detected in all citrus growing regions of the country. Even though serological and biological characteristics of CTV have been studied since the 1980s, molecular characteristics of CTV isolates have not been studied to date in Turkey. In this study, molecular characteristics of 15 CTV isolates collected from different citrus growing regions of Turkey were determined by amplification, cloning, and sequencing of their major coat protein (CP) genes. The sequence analysis showed that the CP genes were highly conserved among Turkish isolates. However, isolates from different regions showed more genetic variation than isolates from the same region. Turkish isolates were clustered into three phylogenetic groups showing no association with geographical origins, host, or symptoms induced in indicator plants. Phylogenetic analysis of Turkish isolates with isolates from different citrus growing regions of the world including well-characterized type isolates of previously established strain specific groups revealed that some Turkish isolates were closely related to severe quick decline or stem pitting isolates. The results demonstrated that although CTV isolates from Turkey are considered biologically mild, majority of them contain severe components potentially causing quick decline or stem pitting.

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Stem Pitting Strains of Citrus Tristeza Virus in Indonesia

International Organization of Citrus Virologists Conference Proceedings (1957-2010) ◽

10.5070/c5160069w8 ◽

1991 ◽

Vol 11 (11) ◽

Author(s):

A. Muharam ◽

A. M. Whittle

Keyword(s):

Citrus Tristeza Virus ◽

Tristeza Virus ◽

Stem Pitting ◽

Citrus Tristeza

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INCIDENCE OF CITRUS TRISTEZA VIRUS, THE STEM PITTING ISOLATES IN THAILAND

Acta Horticulturae ◽

10.17660/actahortic.2008.773.6 ◽

2008 ◽

pp. 51-56

Author(s):

R. Sdoodee ◽

P. Tothaum ◽

J. Worapattamasri ◽

P. Jantaradsamee ◽

S. Patnantawech ◽

...

Keyword(s):

Citrus Tristeza Virus ◽

Tristeza Virus ◽

Stem Pitting ◽

Citrus Tristeza

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Molecular Variability of the 5′- and 3′-Terminal Regions of Citrus Tristeza Virus RNA

Phytopathology ◽

10.1094/phyto.1998.88.7.685 ◽

1998 ◽

Vol 88 (7) ◽

pp. 685-691 ◽

Cited By ~ 65

Author(s):

C. López ◽

M. A. Ayllón ◽

J. Navas-Castillo ◽

J. Guerri ◽

P. Moreno ◽

...

Keyword(s):

Citrus Tristeza Virus ◽

Biological Properties ◽

Terminal Region ◽

Cdna Clones ◽

Reading Frame ◽

Group Iii ◽

Sequence Identity ◽

Virus Rna ◽

Tristeza Virus ◽

Citrus Tristeza

Isolates of citrus tristeza virus (CTV) differ widely in their biological properties. These properties may depend on the structure of viral RNA populations comprising the different isolates. As a first approach to study the molecular basis of the biological variability, we have compared the sequences of multiple cDNA clones of the two terminal regions of the RNA from different CTV isolates. The polymorphism of the 5′ untranslated region (UTR) allowed the classification of the sequences into three groups, with intragroup sequence identity higher than 88% and intergroup sequence identity as low as 44%. The variability of an open reading frame (ORF) 1a segment adjacent to the 5′ UTR supports the same grouping. Some CTV isolates contained sequences of more than one group. Most sequences from Spanish isolates belonged to group III, whereas a Japanese isolate was composed mostly of sequences of groups I and II. The mildest isolates contained only sequences of group III, whereas the most severe isolates also contained sequences of groups I, II, or both. The most stable secondary structure predicted for the 5′ UTR was composed of two stem-loops and remained essentially unchanged as a result of compensatory mutations in the stems and accommodation of most of the variability in the loops. In contrast to the 5′-terminal region, the variability of the 3′-terminal region of CTV RNA was very much restricted, with nucleotide identity values higher than 90%. The presence of a conserved putative “zinc-finger” domain adjacent to a basic region in p23, the predicted product of ORF 11, suggests that this protein might act as a regulatory factor during virus replication.

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