Molecular characterization and potential sources of Citrus tristeza virus in Oman (original) (raw)
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Molecular characterization of Citrus tristeza virus strains in Peninsular Malaysia
African Journal of Microbiology Research, 2011
From six different districts of Punjab, Pakistan, 85 isolates of Citrus tristeza virus (CTV) were collected and characterized based on coat protein gene (CPG) analysis. All isolates were collected from field trees showing various CTV symptoms such as decline in most citrus varieties, inverse pitting on some sour orange rootstocks below bud union, mild-to-moderate stem-pitting on the trunk of some sweet orange. The CTV CP gene of all isolates was amplified by reverse transcriptase polymerase chain reaction (RT-PCR) using CP gene-specific primers yielding 672 bp. The maximum disease incidence was found in sweet orange followed by mandarin and grapefruit. These isolates were then subjected to CPG/Hinf I restriction fragment length polymorphism (RFLP) analysis. Mixed infection of CTV isolates was found very common in the field tress in Pakistan. The most dominant CPG/Hinf I RFLP groups III, I and VI are the basic causal epidemic in Pakistan. Moreover, based on symptoms in the field trees, CPG/Hinf I RFLP groups III, I and VI are considered to be the obvious causes of decline and stem-pitting in Pakistan.
Further Investigations on Citrus tristeza virus (CTV) in Sudan Using Molecular Techniques
Journal of Advances in Biology & Biotechnology, 2017
The natural occurrence of Citrus tristeza clostero virus (CTV) in the main citrus producing regions of Sudan was further substantiated by using a nested RT-PCR approach. Two-thirds of the test samples collected from mandarin, sweet orange, grapefruit, and lime trees reacted positively and a fragment size of 132 bp using an internal and external primer sets were obtained. Cloning and sequencing of these fragments further confirmed the identity of the Sudanese isolates of CTV. The sequence analyses of the first group showed 97% nucleotide identity to a CTV strain from California causing severe stem pitting symptoms (AF01623). The second group was identical to the reference sequence (DSMZ PV-0332 from Israel) and showed 99% identity to CTV strains T30 and T36 from Florida (AF260651 and U 16304). Whereas the third group showed 94% identity to CTV strain T318A from Spain that causes severe stem pitting in sweet orange. The three
Molecular characterization of citrus tristeza virus (CTV) isolates in Calabria region (South Italy)
2009
From six different districts of Punjab, Pakistan, 85 isolates of Citrus tristeza virus (CTV) were collected and characterized based on coat protein gene (CPG) analysis. All isolates were collected from field trees showing various CTV symptoms such as decline in most citrus varieties, inverse pitting on some sour orange rootstocks below bud union, mild-to-moderate stem-pitting on the trunk of some sweet orange. The CTV CP gene of all isolates was amplified by reverse transcriptase polymerase chain reaction (RT-PCR) using CP gene-specific primers yielding 672 bp. The maximum disease incidence was found in sweet orange followed by mandarin and grapefruit. These isolates were then subjected to CPG/Hinf I restriction fragment length polymorphism (RFLP) analysis. Mixed infection of CTV isolates was found very common in the field tress in Pakistan. The most dominant CPG/Hinf I RFLP groups III, I and VI are the basic causal epidemic in Pakistan. Moreover, based on symptoms in the field trees, CPG/Hinf I RFLP groups III, I and VI are considered to be the obvious causes of decline and stem-pitting in Pakistan.
Characterization of Citrus tristeza virus isolates in northern Iran
Journal of General Plant Pathology, 2006
Citrus tristeza virus (CTV) is the causal agent of the most important virus disease of citrus. CTV isolates differing in biological and molecular characteristics have been reported worldwide. Recently, CTV was detected in Syria in citrus groves from two Governorates (Lattakia and Tartous) and several CTV outbreaks have been reported in Apulia (southern Italy) since 2003. To molecularly characterize the CTV populations spreading in Syria and Italy, a number of isolates from each region was selected and examined by different molecular approaches including: Multiple Molecular Markers analysis (MMM), real time RT-(q)PCR, single strand conformation polymorphism (SSCP) of the major coat protein (CP) gene (P25), and sequence analysis of the CP (P25), P18, P20 and RdRp genes. SSCP analysis of CP25 yielded two distinct simple patterns among the Syrian isolates and three different patterns in the Italian isolates. Based on MMM analysis, all Syrian CTV isolates were categorized as VT-like genotype, whereas the Italian isolates reacted only with the markers specific for the T30 genotype. These findings were also confirmed by RT-qPCR and by sequencing analysis of four genomic regions. The Italian isolates had nucleotide identities which varied: from 99.5 to 99.8 for the CP gene; from 97.4% to 98.3% for the P18 gene; from 98.6% to 99.8% for the P20 and from 97.8% to 99.1% for the partial RdRp sequenced. High sequence identity was found for all genomic regions analyzed between the Syrian isolates (from 98.9% to 99.6%). These results show that the CTV populations spreading in Apulia and Syria are associated with different genotypes, indicating different potential impacts on the citrus trees in the field. Since in both areas the introduction of the virus is relatively recent, infected plants resulted to contain a single and common genotype, suggesting that CTV is spreading from the first outbreaks by aphids or local movement of autochthonous infected plant material.
Citrus tristeza virus (CTV) is the causal agent of the most important virus disease of citrus. CTV isolates differing in biological and molecular characteristics have been reported worldwide. Recently, CTV was detected in Syria in citrus groves from two Governorates (Lattakia and Tartous) and several CTV outbreaks have been reported in Apulia (southern Italy) since 2003. To molecularly characterize the CTV populations spreading in Syria and Italy, a number of isolates from each region was selected and examined by different molecular approaches including: Multiple Molecular Markers analysis (MMM), real time RT-(q)PCR, single strand conformation polymorphism (SSCP) of the major coat protein (CP) gene (P25), and sequence analysis of the CP (P25), P18, P20 and RdRp genes. SSCP analysis of CP25 yielded two distinct simple patterns among the Syrian isolates and three different patterns in the Italian isolates. Based on MMM analysis, all Syrian CTV isolates were categorized as VT-like genotype, whereas the Italian isolates reacted only with the markers specific for the T30 genotype. These findings were also confirmed by RT-qPCR and by sequencing analysis of four genomic regions. The Italian isolates had nucleotide identities which varied: from 99.5 to 99.8 for the CP gene; from 97.4% to 98.3% for the P18 gene; from 98.6% to 99.8% for the P20 and from 97.8% to 99.1% for the partial RdRp sequenced. High sequence identity was found for all genomic regions analyzed between the Syrian isolates (from 98.9% to 99.6%). These results show that the CTV populations spreading in Apulia and Syria are associated with different genotypes, indicating different potential impacts on the citrus trees in the field. Since in both areas the introduction of the virus is relatively recent, infected plants resulted to contain a single and common genotype, suggesting that CTV is spreading from the first outbreaks by aphids or local movement of autochthonous infected plant material.
Biological indexing and genetic analysis of Citrus tristeza virus in Pakistan
Journal of General Plant Pathology
include sequences from isolates that cause severe quick decline, seedling yellows and stem pitting (SP) and also from mild isolates. The high percentage of mixed infections is alarming because of the threat of further diversification and spread of severe variants into additional citrus-growing areas of Pakistan and neighboring countries. Eleven CTV isolates from Pakistan were biologically indexed, and most induced mild or mild to moderate reactions on all biological indicators. Four genomic regions of isolate 21C from the biological indexing experiment were sequenced and phylogenetically analysed. These results provide the basis for mild strain cross protection (MSCP) in Pakistan and in neighbouring countries in the near future.
Virus Genes, 1993
The sequences of the coat protein genes of four seedling yellows (SY) and four non-SY (NSY) of citrus tristeza virus (CTV) isolates, which were collected in Israel over a period of 30 years, were analyzed. Pairwise comparisons showed extensive similarities in the nucleotide and amino acid sequences of six isolates designated the VT group. This group consists of three NSY isolates that cause a very mild CTV reaction on the sensitive combination of sweet orange (SwO) grafted on sour orange (SO), and three SY isolates that cause severe SY and SwO/SO reactions. MT, a CTV isolate that is consistently nontransmitted byAphis gossypii, was found to be different in two amino acids (Val 103 and Glu 113) from each of theA. gossypii transmissible CTV isolates. Sequencing of the cDNA clones obtained from ST, a variably transmitted CTV isolate, showed extensive sequence variation among the tested clones. The sequence information indicates that the current CTV epidemics in Israel are caused by at least two CTV subspecies (VT and HT) displaying extensive differences in their coat protein genes.
Occurrence and distribution of Citrus tristeza virus (CTV) in the Jordan Valley
Phytopathologia Mediterranea, 2005
In a survey conducted in 2002 and 2003, Citrus tristeza virus (CTV) was detected in the Jordan Valley. The direct tissue blot immunoassay (DTBIA) indicated that 12.7 and 15.2% of samples tested in the central and northern Jordan Valley respectively were infected with CTV. Similar results showed that all citrus species grown in the Jordan Valley were susceptible to CTV. DAS-ELISA analysis of samples from a citrus orchard in the Dir Alla area with severe CTV symptoms indicated that 49% of samples were infected with CTV. Using a CTV specific primer pair (CTV1/CTV10), the coat protein gene of the virus was successfully amplified from leaf extracts obtained from CTVinfected trees by IC-RT-PCR. After cloning and sequencing the coat protein gene, the sequence of the amplified product was deposited in the GenBank.
Phytopathology, 2010
The emerging diversity of Citrus tristeza virus (CTV) genotypes has complicated detection and diagnostic measures and prompted the search for new differentiation methods. To simplify the identification and differentiation of CTV genotypes, a multiplex reverse-transcription polymerase chain reaction (RT-PCR) technique for the screening of CTV isolates was developed. Variable regions within the open reading frame (ORF)-1a of diverse CTV genotypes were identified to develop first a simplex (S) and then a hexaplex (H) RT-PCR. CTV isolates have been grouped previously into five genotypes (namely, T3, T30, T36, VT, and B165) based on the nucleotide sequence comparisons and phylogenetic analyses. Nucleotide sequences from GenBank were used to design species and genotype-specific primers (GSPs). The GSPs were initially used for reliable detection of all CTV genotypes using S-RT-PCR. Furthermore, detection of all five recognized CTV genotypes was established using the H-RT-PCR. Six amplicons...