Citrus Tristeza Virus: Molecular Approaches to Cross Protection

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.

Download Full-text

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.

Download Full-text

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

Plant Disease ◽

10.1094/pdis-12-19-2586-re ◽

2020 ◽

Vol 104 (9) ◽

pp. 2362-2368

Author(s):

Glynnis Cook ◽

Beatrix Coetzee ◽

Rachelle Bester ◽

Johannes H. J. Breytenbach ◽

Chanel Steyn ◽

...

Keyword(s):

Citrus Tristeza Virus ◽

Aphid Transmission ◽

Common Source ◽

Citrus Paradisi ◽

Full Genome ◽

Full Genome Sequencing ◽

Reading Frame ◽

Tristeza Virus ◽

Stem Pitting ◽

Citrus Tristeza

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.

Download Full-text

Aphid Transmission Alters the Genomic and Defective RNA Populations of Citrus tristeza virus Isolates

Phytopathology ◽

10.1094/phyto.2000.90.2.134 ◽

2000 ◽

Vol 90 (2) ◽

pp. 134-138 ◽

Cited By ~ 39

Author(s):

M. R. Albiach-Martí ◽

J. Guerri ◽

A. Hermoso de Mendoza ◽

F. Laigret ◽

J. F. Ballester-Olmos ◽

...

Keyword(s):

Citrus Tristeza Virus ◽

Blot Hybridization ◽

Aphis Gossypii ◽

Aphid Transmission ◽

Northern Blot Hybridization ◽

Dot Blot ◽

Defective Rnas ◽

Tristeza Virus ◽

Virus Isolates ◽

Citrus Tristeza

A total of 14 Spanish isolates of Citrus tristeza virus (CTV) and 1 isolate from Japan were transmitted by Aphis gossypii, and the subisolates obtained were compared with the source isolates for symptom expression and double-stranded RNA (dsRNA) pattern. Of the 14 Spanish isolates, 9 showed altered dsRNA patterns after aphid transmission but only minor variations in the intensity of symptoms induced on Mexican lime. Northern blot hybridization with complementary DNA (cDNA) probes corresponding to both the 5′ and the 3′ termini of the CTV genomic RNA (gRNA) showed that the dsRNA bands that could be used to discriminate between the dsRNA pattern of the source and the aphid-transmitted isolates were the replicative forms of defective RNAs (D-RNAs). Conversely, the Japanese isolate and two subisolates obtained from it by aphid transmission had the same dsRNA pattern, but one of the subisolates induced milder symptoms in several hosts. Dot-blot hybridization with cDNA probes representing several regions of the gRNA showed that most of the aphid-transmitted isolates differed from the corresponding source isolate by their hybridization pattern. Our results indicate that aphid transmission often sorts the populations of gRNA variants and D-RNAs present in CTV isolates.

Download Full-text

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.

Download Full-text

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.

Download Full-text

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

Download Full-text

A Non-Conserved p33 Protein of Citrus Tristeza Virus Interacts with Multiple Viral Partners

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi-11-19-0328-fi ◽

2020 ◽

Vol 33 (6) ◽

pp. 859-870 ◽

Cited By ~ 2

Author(s):

Thi Nguyet Minh Dao ◽

Sung-Hwan Kang ◽

Aurélie Bak ◽

Svetlana Y. Folimonova

Keyword(s):

Host Range ◽

Citrus Tristeza Virus ◽

Protein A ◽

Integral Membrane Protein ◽

Open Reading Frames ◽

Bimolecular Fluorescence Complementation ◽

In Planta ◽

Tristeza Virus ◽

Citrus Tristeza

The RNA genome of citrus tristeza virus (CTV), one of the most damaging viral pathogens of citrus, contains 12 open reading frames resulting in production of at least 19 proteins. Previous studies on the intraviral interactome of CTV revealed self-interaction of the viral RNA-dependent RNA polymerase, the major coat protein (CP), p20, p23, and p33 proteins, while heterologous interactions between the CTV proteins have not been characterized. In this work, we examined interactions between the p33 protein, a nonconserved protein of CTV, which performs multiple functions in the virus infection cycle and is needed for virus ability to infect the extended host range, with other CTV proteins shown to mediate virus interactions with its plant hosts. Using yeast two-hybrid, bimolecular fluorescence complementation, and coimmunoprecipitation assays, we demonstrated that p33 interacts with three viral proteins, i.e., CP, p20, and p23, in vivo and in planta. Coexpression of p33, which is an integral membrane protein, resulted in a shift in the localization of the p20 and p23 proteins toward the subcellular crude-membrane fraction. Upon CTV infection, the four proteins colocalized in the CTV replication factories. In addition, three of them, CP, p20, and p23, were found in the p33-formed membranous structures. Using bioinformatic analyses and mutagenesis, we found that the N-terminus of p33 is involved in the interactions with all three protein partners. A potential role of these interactions in virus ability to infect the extended host range is discussed.

Download Full-text