scholarly journals Long-term Cross Protection of Severe Stem Pitting Citrus tristeza virus in Peru

2010 ◽  
Vol 17 (17) ◽  
Author(s):  
K. Bederski ◽  
C. N. Roistacher ◽  
O P Silvestre ◽  
G. W. Müller
Keyword(s):  
Citrus Tristeza Virus ◽  
Cross Protection ◽  
Tristeza Virus ◽  
Stem Pitting ◽  
Citrus Tristeza

scholarly journals Characterization of Citrus tristeza virus Single-Variant Sources in Grapefruit in Greenhouse and Field Trials

Plant Disease ◽  
2016 ◽  
Vol 100 (11) ◽  
pp. 2251-2256 ◽  
Author(s):  
Glynnis Cook ◽  
Stephanus P. van Vuuren ◽  
Johannes H. J. Breytenbach ◽  
Chanel Steyn ◽  
Johan T. Burger ◽  
...  
Keyword(s):  
Citrus Tristeza Virus ◽  
Phenotypic Expression ◽  
Field Trials ◽  
Cross Protection ◽  
Enzyme Linked Immunosorbent Assay ◽  
Limiting Factor ◽  
Phenotypic Effect ◽  
Tristeza Virus ◽  
Stem Pitting ◽  
Citrus Tristeza

Citrus tristeza virus (CTV) is endemic to southern Africa and the stem pitting syndrome that it causes was a limiting factor in grapefruit production prior to the introduction of cross-protection in the Citrus Improvement Scheme. This disease mitigation strategy, using various field-derived CTV sources, has significantly extended the productive lifespan of grapefruit orchards in South Africa. CTV commonly occurs as a population of various strains, masking the phenotypic effect of individual strains. Likewise, current South African CTV cross-protection sources are strain mixtures, obscuring an understanding of which strains are influencing cross-protection. The severity of various CTV strains has mostly been assessed on sensitive indicator hosts, but their effect on commercial varieties has seldom been investigated. Single-variant CTV isolates were used to investigate the phenotypic expression of CTV strains in commercial grapefruit varieties as well as CTV indicator hosts. They were biologically characterized for their ability to cause stem pitting and their rate of translocation and titer in the different hosts, monitored by enzyme-linked immunosorbent assay. Complete genome sequences for three CTV strain variants were generated. Isolates of CTV strains VT, T68, RB, and HA16-5 did not induce severe stem pitting in four grapefruit hosts in a glasshouse trial. Viral titers of the strains differed in the grapefruit hosts, but the RB isolate reached a higher titer in the grapefruit hosts compared with the VT, T68, and HA16-5 isolates. Additionally, horticultural assessment of two grapefruit varieties inoculated with the RB isolate in two field trials demonstrated that mild stem pitting did not negatively influence the horticultural performance of the grapefruit trees over an eight-year assessment period. ‘Star Ruby’ trees containing the CTV source GFMS35 showed less stem pitting than trees inoculated with the RB isolate, but had smaller canopy volumes and lower yields than trees containing the RB isolate. This suggests that the influence of CTV sources on tree performance is not limited to the effect of stem pitting.

Grapefruit Field Trial Evaluation of Citrus Tristeza Virus T68-Strain Sources

Plant Disease ◽  
2020 ◽  
pp. PDIS-06-20-1259
Author(s):  
Glynnis Cook ◽  
Johannes H. J. Breytenbach ◽  
Chanel Steyn ◽  
Rochelle de Bruyn ◽  
Stephanus P. van Vuuren ◽  
...  
Keyword(s):  
Field Trial ◽  
Citrus Tristeza Virus ◽  
Growth Yield ◽  
Field Application ◽  
Limpopo Province ◽  
Long Term Effects ◽  
Tristeza Virus ◽  
Stem Pitting ◽  
Citrus Tristeza

Determination of virus genomes and differentiation of strains and strain variants facilitate the linkage of biological expression to specific genetic units. For effective management of stem pitting disease of citrus tristeza virus (CTV) by cross-protection, an understanding of these links is necessary. The deliberate field application of a biological agent such as a virus first requires a thorough assessment of the long-term impact before it can be applied commercially. Three CTV sources were genetically characterized as different variants of the T68 strain, and their long-term effects on stem pitting and production were investigated. The different CTV sources were inoculated to ‘Star Ruby’ grapefruit trees and evaluated for a number of biological parameters in a field trial in the Limpopo Province of South Africa over a 10-year period. Significant differences were observed in stem pitting severity, impact on tree growth, yield, and the percentage of small fruit produced. These T68 variants were also associated with different stem pitting phenotypes. The variants differed in only 44 nucleotide positions across their genomes, and these minor genetic differences can therefore be used to identify possible genome regions affecting stem pitting.

Production of Antibodies to Citrus Tristeza Virus in Transgenic Citrus

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.

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

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
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.

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.

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