scholarly journals Studies on Mild Strain Cross Protection Against Stem-pitting Citrus tristeza virus

2002 ◽  
Vol 15 (15) ◽  
Author(s):  
C. Y. Zhou ◽  
D. L. Hailstones ◽  
P. Broadbent ◽  
R. Connor ◽  
J. Bowyer
Keyword(s):  
Citrus Tristeza Virus ◽  
Cross Protection ◽  
Mild Strain ◽  
Tristeza Virus ◽  
Stem Pitting ◽  
Citrus Tristeza

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. 

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.

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.

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