Involvement of a subgenomic mRNA in the generation of a variable population of defective citrus tristeza virus molecules

Yang, Guang; Mawassi, Munir; Gofman, Rose; Gafny, Ron; Bar‐Joseph, M.

doi:10.1128/jvi.71.12.9800-9802.1997

Cited by 37 publications

(15 citation statements)

References 21 publications

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“…Those large D‐RNAs resemble RNAs 1 and 2 of criniviruses (family Closteroviridae ). Sequence analysis of the junction site and flanking regions suggest that most D‐RNAs must be generated by a template‐switching mechanism induced by different factors (Ayllón et al ., 1999a; Yang et al ., 1997). The minimal replication signals required for D‐RNA replication in trans are located in the 5′ proximal 1 kb and at the 3′‐UTR of the D‐RNA sequence (Mawassi et al ., 2000a,b).…”

Section: Ctv Structure Genome Organization and Expressionmentioning

confidence: 99%

“…Homologous and non‐homologous recombination might be a fast means for CTV evolution. Non‐homologous recombination giving rise to multiple D‐RNAs have been widely documented (Ayllón et al ., 1999a; Guerri et al ., 1991; Mawassi et al ., 1995a,b; Yang et al ., 1997). Homologous recombination was first observed when comparing the gRNA sequence of isolates T36 or SY568 with that of other isolates (Mawassi et al ., 1996; Vives et al ., 1999, 2005) and later confirmed by additional sequence comparisons.…”

Section: Ctv Diagnosis Strain Characterization and Genetic Variationmentioning

confidence: 99%

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Citrus tristeza virus: a pathogen that changed the course of the citrus industry

Moreno

Ambrós²,

Albiach-Martı́³

et al. 2007

Molecular Plant Pathology

411

425

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Citrus tristeza virus (CTV) (genus Closterovirus, family Closteroviridae) is the causal agent of devastating epidemics that changed the course of the citrus industry. Adapted to replicate in phloem cells of a few species within the family Rutaceae and to transmission by a few aphid species, CTV and citrus probably coevolved for centuries at the site of origin of citrus plants. CTV dispersal to other regions and its interaction with new scion varieties and rootstock combinations resulted in three distinct syndromes named tristeza, stem pitting and seedling yellows. The first, inciting decline of varieties propagated on sour orange, has forced the rebuilding of many citrus industries using tristeza-tolerant rootstocks. The second, inducing stunting, stem pitting and low bearing of some varieties, causes economic losses in an increasing number of countries. The third is usually observed by biological indexing, but rarely in the field. CTV polar virions are composed of two capsid proteins and a single-stranded, positive-sense genomic RNA (gRNA) of approximately 20 kb, containing 12 open reading frames (ORFs) and two untranslated regions (UTRs). ORFs 1a and 1b, encoding proteins of the replicase complex, are directly translated from the gRNA, and together with the 5' and 3'UTRs are the only regions required for RNA replication. The remaining ORFs, expressed via 3'-coterminal subgenomic RNAs, encode proteins required for virion assembly and movement (p6, p65, p61, p27 and p25), asymmetrical accumulation of positive and negative strands during RNA replication (p23), or suppression of post-transcriptional gene silencing (p25, p20 and p23), with the role of proteins p33, p18 and p13 as yet unknown. Analysis of genetic variation in CTV isolates revealed (1) conservation of genomes in distant geographical regions, with a limited repertoire of genotypes, (2) uneven distribution of variation along the gRNA, (3) frequent recombination events and (4) different selection pressures shaping CTV populations. Measures to control CTV damage include quarantine and budwood certification programmes, elimination of infected trees, use of tristeza-tolerant rootstocks, or cross protection with mild isolates, depending on CTV incidence and on the virus strains and host varieties predominant in each region. Incorporating resistance genes into commercial varieties by conventional breeding is presently unfeasible, whereas incorporation of pathogen-derived resistance by plant transformation has yielded variable results, indicating that the CTV-citrus interaction may be more specific and complex than initially thought. A deep understanding of the interactions between viral proteins and host and vector factors will be necessary to develop reliable and sound control measures.

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Section: Ctv Structure Genome Organization and Expressionmentioning

confidence: 99%

Section: Ctv Diagnosis Strain Characterization and Genetic Variationmentioning

confidence: 99%

Citrus tristeza virus: a pathogen that changed the course of the citrus industry

Moreno

Ambrós²,

Albiach-Martı́³

et al. 2007

Molecular Plant Pathology

411

425

View full text Add to dashboard Cite

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“…In addition to the gRNA and sgRNAs, CTV‐infected tissues often contain defective RNAs (D‐RNAs) which have the 5′‐ and 3′ terminal regions of the gRNA but lack a variable segment of the central region (Mawassi et al . 1995; Yang et al . 1997; Ayllón et al .…”

Section: Introductionmentioning

confidence: 99%

Variation of haplotype distributions of two genomic regions of Citrus tristeza virus populations from eastern Spain

et al. 2003

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Genetic variation in natural populations of Citrus tristeza virus (CTV) was studied using haplotypes detected by single-strand conformation polymorphism (SSCP) analysis of two genomic regions (p20 gene and segment A, located in ORF1a). Analysis of 254 samples from 125 trees, collected at 12 different sites, yielded 8 different haplotypes for p20 and 5 for segment A. The most frequent haplotype of p20 was predominant at all sites, but several sites differed in the predominance of segment A haplotypes. At most sites, the homozygosity observed for the p20 gene tended to be higher than expected in a neutral evolution, whereas the opposite was true for segment A. Comparison of the populations at different sites showed that 44 of the 66 possible population pairs were genetically distinct for segment A, but only six pairs differed for the p20 gene. Analysis of molecular variance grouping trees by site, scion variety, rootstock or age, showed that variation in segment A was significantly affected by site, tree age and rootstock, and that variation between trees in each group and within trees was even more important. In contrast, variation in p20 was affected only by site and rootstock, each factor contributing to < 2% of the variation. The data suggest that sequence variations in segment A must be functionally less important and that it has less evolutionary constraints than p20. Detection of different haplotypes in neighbour trees or in samples from the same tree may help explain part of the variability observed in CTV symptom expression.

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“…Los dRNA se generan por sucesos de recombinación no homóloga mediante diversos mecanismos como la rotura, ligación entre diferentes cadenas, cambio de molde en la replicación o por finalización del molde original (Nagy y Simon, 1997). La gran mayoría de los dRNA de CTV caracterizados hasta la fecha consisten en la fusión directa de fragmentos de tamaños variable de los extremos 5´ y 3´ (Mawassi et al, 1995a, b;Yang et al, 1997Yang et al, , 1999Ayllón et al, 1999a). La mayoría de aislados de CTV presentan uno o más dRNAs con tamaños que varían entre 2 y 5 Kb (Dodds et al, 1987;Moreno et al, 1990;Guerri et al, 1991;Mawassi et al, 1995a, b).…”

Section: Figuraunclassified

“…Los virus de RNA, como CTV, pueden evolucionar con rapidez mediante procesos de mutación debido a que las RdRp presentan una alta tasa de error, al carecer de función correctora (Domingo y Holland, 1997). La recombinación homóloga y no-homóloga podría ser un proceso rápido de evolución de CTV, pues esta segunda, ha sido ampliamente documentada en la generación de dRNAs Mawassi et al, 1995a, b;Yang et al, 1997: Ayllón et al, 1999a. Se han comprobado diferencias de secuencias compatibles con la deriva genética, asociadas con la disminución del tamaño eficaz en las poblaciones virales, causado por los cuellos de botella que suponen la transmisión por pulgones o el cambio de huésped (Albiach-Martí et al, 2000b;Ayllón et al, 2006;Sentandreu et al, 2006).…”

Section: Variabilidad Genéticaunclassified

Estudio De La Interacción Diferencial Entre Aislados Del Virus De La Tristeza De Los Cítricos (Ctv) Y Sus Huéspedes

Muñoz¹

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Involvement of a subgenomic mRNA in the generation of a variable population of defective citrus tristeza virus molecules

Cited by 37 publications

References 21 publications

Citrus tristeza virus: a pathogen that changed the course of the citrus industry

Citrus tristeza virus: a pathogen that changed the course of the citrus industry

Variation of haplotype distributions of two genomic regions of Citrus tristeza virus populations from eastern Spain

Estudio De La Interacción Diferencial Entre Aislados Del Virus De La Tristeza De Los Cítricos (Ctv) Y Sus Huéspedes

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