Identification and Characterization of Citrus tristeza virus Isolates Breaking Resistance in Trifoliate Orange in California

Most Citrus tristeza virus (CTV) isolates in California are biologically mild and symptomless in commercial cultivars on CTV tolerant rootstocks. However, to better define California CTV isolates showing divergent serological and genetic profiles, selected isolates were subjected to deep sequencing of small RNAs. Full-length sequences were assembled, annotated and trifoliate orange resistance-breaking (RB) isolates of CTV were identified. Phylogenetic relationships based on their full genomes placed three isolates in the RB clade: CA-RB-115, CA-RB-AT25, and CA-RB-AT35. The latter two isolates were obtained by aphid transmission from Murcott and Dekopon trees, respectively, containing CTV mixtures. The California RB isolates were further distinguished into two subclades. Group I included CA-RB-115 and CA-RB-AT25 with 99% nucleotide sequence identity with RB type strain NZRB-G90; and group II included CA-RB-AT35 with 99 and 96% sequence identity with Taiwan Pumelo/SP/T1 and HA18-9, respectively. The RB phenotype was confirmed by detecting CTV replication in graft-inoculated Poncirus trifoliata and transmission from P. trifoliata to sweet orange. The California RB isolates induced mild symptoms compared with severe isolates in greenhouse indexing tests. Further examination of 570 CTV accessions, acquired from approximately 1960 and maintained in planta at the Central California Tristeza Eradication Agency, revealed 16 RB positive isolates based on partial p65 sequences. Six isolates collected from 1992 to 2011 from Tulare and Kern counties were CA-RB-115-like; and 10 isolates collected from 1968 to 2010 from Riverside, Fresno, and Kern counties were CA-RB-AT35-like. The presence of the RB genotype is relevant because P. trifoliata and its hybrids are the most popular rootstocks in California.

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A Novel Gene Conferring Citrus Tristeza Virus Resistance in Citrus maxima (Burm.) Merrill

HortScience ◽

10.21273/hortsci.34.2.334 ◽

1999 ◽

Vol 34 (2) ◽

pp. 334-335 ◽

Cited By ~ 15

Author(s):

D.Q. Fang ◽

M.L. Roose

Keyword(s):

Virus Resistance ◽

Citrus Tristeza Virus ◽

Dominant Gene ◽

Poncirus Trifoliata ◽

Trifoliate Orange ◽

Citrus Maxima ◽

Progeny Analysis ◽

Citrus Tristeza Virus Resistance ◽

Tristeza Virus ◽

Citrus Tristeza

`Chandler' pummelo [Citrus maxima (Burm.) Merrill] was found to be citrus tristeza virus (CTV)–resistant. The inheritance of this resistance in 84 progeny of two crosses derived from `Chandler' pummelo and trifoliate orange [Poncirus trifoliata (L.) Raf.] was controlled by a single dominant gene designated Ctv2. Progeny analysis of four molecular markers closely linked to the Ctv gene, which confers resistance to CTV in trifoliate orange, demonstrated that Ctv2 was an independently assorting gene from Ctv.

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Isolates of Citrus tristeza virus that overcome Poncirus trifoliata resistance comprise a novel strain

Archives of Virology ◽

10.1007/s00705-010-0604-5 ◽

2010 ◽

Vol 155 (4) ◽

pp. 471-480 ◽

Cited By ~ 48

Author(s):

S. J. Harper ◽

T. E. Dawson ◽

M. N. Pearson

Keyword(s):

Citrus Tristeza Virus ◽

Poncirus Trifoliata ◽

Tristeza Virus ◽

Citrus Tristeza

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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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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.

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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.

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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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