scholarly journals Segregation of Distinct Variants from Citrus tristeza virus Isolate SY568 Using Aphid Transmission

2009 ◽  
Vol 99 (10) ◽  
pp. 1168-1176 ◽  
Author(s):  
J. J. Velazquez-Monreal ◽  
D. M. Mathews ◽  
J. A. Dodds
Keyword(s):  
Citrus Tristeza Virus ◽  
Aphid Transmission ◽  
Single Infection ◽  
Mild Strain ◽  
Rnase Protection ◽  
Genetic Characteristics ◽  
Inoculum Sources ◽  
Tristeza Virus ◽  
Severe Isolate ◽  
Citrus Tristeza

A well-studied severe isolate of Citrus tristeza virus (CTV) known as SY568 has previously been shown to contain multiple variants of the virus which differ in their genetic and biological characters. Aphid transmission was used in an attempt to segregate some of these variants for further characterization. Resulting infections gave symptoms which varied from asymptomatic to more severe than the inoculum source. RNase protection assays (RPAs) were used to compare nine regions of the CTV genome and determine whether unique strains could be identified. Five aphid-transmitted subcultures, with fingerprints that were different from those of the inoculum sources in at least one genomic area, were then cloned, sequenced, and compared with known isolates. An asymptomatic strain was shown to be different in every area of the CTV genome when examined by RPA and sequencing of selected regions. Mixed-infection studies using graft transmission of the asymptomatic subculture and two of the more severe aphid-transmitted subcultures showed that the mild strain was not able to compete well when in the presence of any of the severe variants tested, and its titer was significantly reduced from that seen in single infection. The mild strain and a selected severe strain were singly graft inoculated into five different citrus hosts (sweet orange, grapefruit, sour orange, lemon, and lime), where they maintained their distinct biological and genetic characteristics.

scholarly journals Examination of the Effect of Aphid Vector Population Composition on the Spatial Dynamics of Citrus Tristeza Virus Spread by Stochastic Modeling

1999 ◽  
Vol 89 (7) ◽  
pp. 603-608 ◽  
Author(s):  
T. R. Gottwald ◽  
G. J. Gibson ◽  
S. M. Garnsey ◽  
M. Irey
Keyword(s):  
Citrus Tristeza Virus ◽  
Nearest Neighbor ◽  
Disease Spread ◽  
Virus Spread ◽  
Population Composition ◽  
Inoculum Sources ◽  
Aphid Vector ◽  
Melon Aphid ◽  
Tristeza Virus ◽  
Citrus Tristeza

Aphid vector species population composition is known to affect the spatial patterns of citrus tristeza virus (CTV) and the changes in these patterns over time. However, the biological processes that are associated with virus spread have not been well defined. The spatiotemporal dynamics of CTV were examined using data collected from research plots in the Dominican Republic and Costa Rica, where the brown citrus aphid (BCA), Toxoptera citricida, was the predominant species, and in Florida, where the BCA was absent and the melon aphid, Aphis gossypii, was the predominant vector. Data were analyzed using a spatiotemporal stochastic model for disease spread, and parameter values were evaluated using Markov chain Monte Carlo stochastic integration methods. Where the melon aphid was the dominant species, the model parameter likelihood values supported the hypothesis that the disease was spread through a combination of random background transmission (transmission originating from inoculum sources outside the plot) and a local interaction (transmission from inoculum sources within the plot) operating over short distances. Conversely, when BCA was present, results often suggested a local short-range transmission interaction that was not restricted to nearest-neighbor interactions and that the presence of background infection was not necessary to explain the observations.

scholarly journals 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 ◽  
2011 ◽  
Vol 95 (8) ◽  
pp. 913-920 ◽  
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.

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

Plant Disease ◽  
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.

scholarly journals The Haplotype Distribution of Two Genes of Citrus Tristeza Virus Is Altered after Host Change or Aphid Transmission

Virology ◽  
1999 ◽  
Vol 255 (1) ◽  
pp. 32-39 ◽  
Author(s):  
Marı́a A. Ayllón ◽  
Luis Rubio ◽  
Andrés Moya ◽  
José Guerri ◽  
Pedro Moreno
Keyword(s):  
Citrus Tristeza Virus ◽  
Aphid Transmission ◽  
Haplotype Distribution ◽  
Tristeza Virus ◽  
Citrus Tristeza

scholarly journals Separation of Citrus Tristeza Virus Isolates in Mixed Infections through Transfer by Single Brown Citrus Aphids

HortScience ◽  
2005 ◽  
Vol 40 (3) ◽  
pp. 694-696 ◽  
Author(s):  
Charles A. Powell ◽  
Youjian Lin
Keyword(s):  
Citrus Tristeza Virus ◽  
Sweet Orange ◽  
Mixed Infections ◽  
Citrus Paradisi ◽  
Inoculum Sources ◽  
Toxoptera Citricida ◽  
Orange Trees ◽  
Tristeza Virus ◽  
Virus Isolates ◽  
Citrus Tristeza

One hundred single brown citrus aphid (BCA) (Toxoptera citricida Kirkaldy) transmission attempts were made from each of 16 different citrus trees [8 grapefruit (Citrus paradisi Macf.) and 8 sweet orange (C. sinensis (L.) Osbeck)] previously inoculated with decline-inducing (T36-CTV), non-decline-inducing (T30-CTV), a mixture of the two Citrus tristeza virus isolate types, or no CTV. Successful CTV transmission occurred in 1.5% of attempts from grapefruit trees that had been bark-chip-inoculated with T36-CTV, 3% of attempts from orange trees inoculated with T36-CTV, 3% of attempts from grapefruit trees inoculated with both T36- and T30-CTV, 4% of attempts from orange trees inoculated with both T36- and T30-CTV, 1.5% of attempts from grapefruit trees inoculated with T30-CTV, and 3.5% of attempts from orange trees inoculated with T30-CTV. Single BCA were able to recover T30-like-CTV from trees believed to be inoculated only with T36-CTV, and T36-like-CTV from trees believed to be inoculated only with T30-CTV, suggesting that these inoculum sources were also mixtures of T36-CTV and T30-CTV. The T36-CTV was not immunologically detectable in some of the trees from which it was transmitted indicating that single BrCA can recover T36-CTV from a T36-CTV/T30-CTV mixture in which the T36-CTV is an undetectable, minority component.

scholarly journals CITRUS TRISTEZA VIRUS IN PAKISTAN: A REVIEW

2017 ◽  
Vol 29 (2) ◽  
pp. 273
Author(s):  
Sagheer Atta ◽  
Maroof Siddiq ◽  
Sidra Ashiq ◽  
Abdul Hannan
Keyword(s):  
Transgenic Plants ◽  
Citrus Tristeza Virus ◽  
Economic Losses ◽  
Mild Strain ◽  
Viral Pathogen ◽  
Vein Clearing ◽  
The World ◽  
Tristeza Virus ◽  
Stem Pitting ◽  
Citrus Tristeza

Citrus is one of the most widely grown fruit crop in the world. Citrus tristeza virus (CTV) is one of the most economically important viral pathogen of citrus and causes different disease syndromes. The use of infected bud wood and aphids are the main cause of spread of CTV. The virus is genetically diverse and causes various symptoms like slow and quick decline, stunting, stem pitting, vein clearing and seedling yellows. Strategies have been developed to reduce the economic losses caused by CTV. Quarantine measures, bud wood certification, mild strain cross protection and eradication programs are some of the strategies that can prevent the spread of this disease. New approaches are provided by advancement in genetic engineering and molecular biology. Transgenic plants have been developed to provide resistance against the disease. 

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