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Yang, Guang; Che, Xibing; Gofman, Rose; Ben-Shalom, Yossi; Piestun, Dan; Gafny, Ron; Mawassi, Munir; Bar‐Joseph, M.

doi:10.1023/a:1008105004407

Cited by 18 publications

(3 citation statements)

References 21 publications

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“…All three of them harbor CP sequences of reference isolates that cause severe CTV symptoms of stem pitting, quick decline, and seedling yellows [21,33]. Due to the fact that sweet orange does not display the seedling yellows syndrome [34], no visible symptoms had been initially observed in Fukumoto orange. However, later inspection confirmed the presence of severe stem pitting.…”

Section: Discussionmentioning

confidence: 99%

Stem pitting and seedling yellows symptoms of Citrus tristeza virus infection may be determined by minor sequence variants

et al. 2007

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The isolates of Citrus tristeza virus (CTV), the most destructive viral pathogen of citrus, display a high level of variability. As a result of genetic bottleneck induced by the bud-inoculation of CTV-infected material, inoculated seedlings of Citrus wilsonii Tanaka displayed different symptoms. All successfully grafted plants showed severe symptoms of stem pitting and seedling yellows, while plants in which inoculated buds died displayed mild symptoms. Since complex CTV population structure was detected in the parental host, the aim of this work was to investigate how it changed after the virus transmission, and to correlate it with observed symptoms. The coat protein gene sequence of the predominant genotype was identical in parental and grafted plants and clustered to the phylogenetic group 5 encompassing severe reference isolates. In seedlings displaying severe symptoms, the low-frequency variants clustering to other phylogenetic groups were detected, as well. Indicator plants were inoculated with buds taken from unsuccessfully grafted C. wilsonii seedlings. Surprisingly, they displayed no severe symptoms despite the presence of phylogenetic group 5 genomic variants. The results suggest that the appearance of severe symptoms in this case is probably induced by a complex CTV population structure found in seedlings displaying severe symptoms, and not directly by the predominant genomic variant.

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Section: Discussionmentioning

confidence: 99%

Stem pitting and seedling yellows symptoms of Citrus tristeza virus infection may be determined by minor sequence variants

et al. 2007

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“…The pathogenicity determinants of CTV have not yet been identified, although p20 gene has been characterized as an RNA silencing suppressor [21]. Different factors have been suggested to potentially contribute to biological variability of CTV isolates, namely, genetic variation of different genes, repeated inoculations in the field, homologous RNA recombination between sequence variants, and the presence of different defective RNAs [10,37,38,43,63,64]. Data presented here suggest that alteration of the genetic structure of isolates in field trees, caused by aphid transmission or by host change after topworking to new varieties, also might increase biological and genetic diversity of CTV.…”

Section: Discussionmentioning

confidence: 99%

Variations in Two Gene Sequences of Citrus Tristeza Virus after Host Passage

et al. 2006

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We estimated genetic variation in two groups of Citrus tristeza virus (CTV) isolates: one of them (isolates T385, T317, T318 and T305) derived from a Spanish source by successive host passages, and the other (isolates T388 and T390), obtained after aphid transmission of a Japanese source. The population structure of these isolates had been characterized by single-strand conformation polymorphism analysis of genes p18 and p20. The nucleotide sequences of representative haplotypes of each isolate and gene were used to estimate genetic diversity within and between isolates and to evaluate genetic differentiation between populations. Phylogenetic analysis of p18 and p20 sequence variants showed two main groups: one them included variants predominant in the severe isolates (T318, T305 and T388), and the other comprised variants present in both mild (T385, T317) and severe isolates. Most sequence variants of isolate T390 were not associated to these groups. In some isolates, within-isolate diversity was higher than diversity with other isolates because their population contained distantly related sequence variants, some of which were genetically close to variants predominant in the second isolate. Isolates T388 and T390 were genetically different for the two genes, as estimated by the F statistic. Furthermore, genetic differentiation between T385 and T317, T318 and T305 increased after each host passage. Our results suggest that aphid transmission and host passage may significantly alter the composition of CTV populations and thus be an important factor in their evolution.

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“…Whether the presence of an extra G at the 3Ј terminus of the minus strand in the ORF 10 sgRNA double-stranded equivalent plays a role in the CTV replication remains to be determined. The presence of an extra G was also recorded for some ORF 11 sgRNA doublestranded equivalents in another CTV isolate, VT (29), where it is perhaps involved in recombination and defective RNA formation (21,22).…”

mentioning

confidence: 86%

Transcriptional strategy of closteroviruses: mapping the 5' termini of the citrus tristeza virus subgenomic RNAs

Karasev

Hilf

Garnsey

et al. 1997

J Virol

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Citrus tristeza virus (CTV) induces formation of a nested set of at least nine 3 coterminal subgenomic RNAs (sgRNAs) in infected tissue. The organization and expression of the 19,296-nucleotide (nt) CTV genome resembles that of coronaviruses, with polyprotein processing, translational frameshifting, and multiple sgRNA formation, but phylogenetically the CTV polymerase, like polymerases of other closteroviruses, belongs to the Sindbis virus-like lineage of RNA virus polymerases. Both positive-strand RNA virus supergroups, coronaviruses and Sindbis-like viruses, utilize different mechanisms of transcription. To address the mechanism of CTV transcription, 5 termini for the two most abundant sgRNAs, 1.5 and 0.9 kb, respectively, were mapped by runoff reverse transcription. The two sgRNAs were demonstrated to have 48-and 38-nt 5 untranslated regions (5-UTRs), respectively. The 5-UTR for the 1.5-kb RNA was cloned, sequenced, and demonstrated to be colinear with the 48-nt genomic sequence upstream of the initiator codon of the respective open reading frame 10, i.e., to be of continuous template origin. The data obtained suggest that the sgRNA transcription of CTV is dissimilar from the coronavirus transcription and consistent with the transcriptional mechanism of other Sindbis-like viruses. Thus, the Sindbis virus-like mechanism of transcription of the positive-strand RNA genomes might be successfully utilized by the closterovirus genome of up to 19.3 kb with multiple sgRNAs.

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Cited by 18 publications

References 21 publications

Stem pitting and seedling yellows symptoms of Citrus tristeza virus infection may be determined by minor sequence variants

Stem pitting and seedling yellows symptoms of Citrus tristeza virus infection may be determined by minor sequence variants

Variations in Two Gene Sequences of Citrus Tristeza Virus after Host Passage

Transcriptional strategy of closteroviruses: mapping the 5' termini of the citrus tristeza virus subgenomic RNAs

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