Dahlia

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Hanu R. Pappu - One of the best experts on this subject based on the ideXlab platform.

  • Characterization and comparative analysis of promoters from three plant pararetroviruses associated with Dahlia (Dahlia variabilis)
    Virus genes, 2015
    Co-Authors: C. V. Almeyda, G. Raikhy, Hanu R. Pappu
    Abstract:

    Two distinct caulimoviruses, Dahlia mosaic virus (DMV) and Dahlia common mosaic virus (DCMV), and an endogenous plant pararetroviral sequence (DvEPRS, formerly known as DMV-D10) were reported from Dahlia (Dahlia spp). Promoter elements from these Dahlia-associated pararetroviruses were identified and characterized. The TATA box, the CAAT box, the transcription start site, the polyadenylation signal, and regulation factors, characteristic of caulimovirus promoters, were present in each of these promoter regions. Each of the promoter regions was separately cloned into a binary vector containing β-glucuronidase (GUS) reporter gene and delivered into Agrobacterium tumefaciens by electroporation followed by agroinfiltration into Nicotiana benthamiana. The activity of the 35S promoter homologs was determined by transient expression of the GUS gene both in qualitative and quantitative assays. The length of the promoter regions in DMV, DCMV, and DvEPRS corresponded to 438, 439, and 259 bp, respectively. Quantitative GUS assays showed that the promoters from DMV and DCMV resulted in higher levels of gene expression compared to that of DvEPRS in N. benthamiana leaf tissue. Significant differences were observed among the three promoters (p < 0.001). Qualitative GUS assays were consistent with quantitative GUS results. This study provides important information on new promoters for prospect applications as novel promoters for their potential use in foreign gene expression in plants.

  • Genomic characterization of pararetroviral sequences in wild Dahlia spp. in natural habitats
    Archives of virology, 2011
    Co-Authors: Sahar Eid, C. V. Almeyda, D. E. Saar, K. L. Druffel, Hanu R. Pappu
    Abstract:

    The genome structure and organization of endogenous caulimovirus sequences from Dahlia (Dahlia spp), Dahlia mosaic virus (DMV)-D10 from three wild species, D. coccinea (D10-DC), D. sherffii (D10-DS) and D. tenuicaulis (D10-DT), were determined and compared to those from cultivated species of Dahlia, D. variabilis (DvEPRS). The complete ca. 7-kb dsDNA genomes of D10-DC, D10-DS, and D10-DT had a structure and organization typical of a caulimovirus and shared 89.3 to 96.6% amino acid sequence identity in various open reading frames (ORF) when compared to DvEPRS. The absence of the aphid transmission factor and the truncated coat protein fused with the reverse transcriptase ORF were common among these DMV-D10 isolates from wild Dahlia species.

  • Plant pararetroviral sequences in wild Dahlia species in their natural habitats in Mexican mountain ranges
    Plant Pathology, 2010
    Co-Authors: Sahar Eid, D. E. Saar, K. L. Druffel, Hanu R. Pappu
    Abstract:

    Selected wild Dahlia species in their natural habitats from west-central Mexico were tested for the presence of three caulimoviruses known to be associated with cultivated Dahlia (Dahlia variabilis), viz. Dahlia mosaic virus (DMV), DMV-D10 and Dahlia common mosaic virus. Virus species-specific primers and PCR were used followed by cloning and sequencing of the amplicons. Results showed that the wild Dahlia species in their natural habitat contained DMV-D10, which is an endogenous plant pararetrovirus. Viral sequences were found in 91% of the samples (n = 56) representing four different wild species. The gene coding for the movement protein of DMV-D10 from Dahlia coccinea and all other species was cloned and sequenced. Sequence comparisons showed divergence of this gene when compared to that of DMV-D10 from cultivated Dahlias. The discovery of plant pararetroviruses in wild Dahlia species in their natural habitats suggests a possible emergence, co-existence and co-evolution of pararetroviruses and their host plants.

  • Incidence of Multiple and Distinct Species of Caulimoviruses in Dahlia (Dahlia variabilis)
    HortScience, 2009
    Co-Authors: Sahar Eid, K. L. Druffel, Dayle E. Saar, Hanu R. Pappu
    Abstract:

    Dahlia mosaic is a serious disease affecting Dahlias. In addition to the Dahlia mosaic virus (DMV) reported previously, we characterized two putative new caulimoviruses, tentatively designated as DMV-D10 and Dahlia common mosaic virus (DCMV), from Dahlia. To better understand their relative incidence in Dahlia, a total of 213 samples were collected during 2007 and 2008 from several varieties of cultivated Dahlia (D. variabilis) in the United States. Samples were tested for the three caulimoviruses using virus-specific primers in a polymerase chain reaction. Amplicons were cloned and sequenced to confirm the infection of Dahlia with these viruses. Results showed that DMV-D10 was the most prevalent (94%) followed by DCMV (48.5%) and DMV (23%). Mixed infections were common and viruses were detected irrespective of symptom expression at the time of sampling. Two percent of the samples were not infected by any of the three tested caulimoviruses. Results suggest that caulimovirus infections are widespread in Dahlia and highlight the need for testing and production of virus-free material to reduce their spread.

  • Nucleotide sequence and genome organization of a member of a new and distinct Caulimovirus species from Dahlia
    Archives of virology, 2008
    Co-Authors: Hanu R. Pappu, R. Miglino, K. L. Druffel, A. R. Van Schadewijk
    Abstract:

    A distinct caulimovirus, associated with Dahlia mosaic, was cloned and sequenced. The caulimovirus, tentatively designated as Dahlia common mosaic virus (DCMV), had a double-stranded DNA genome of ca. 8 kb. The genome organization of DCMV was found to be typical of members of the genus Caulimovirus and consisted of six major open reading frames (ORFs), ORFs I-VI, and one minor ORF, ORF VII. Sequence comparisons with the DNA genomes of two known caulimoviruses isolated from Dahlia, Dahlia mosaic virus (DMV) and an endogenous caulimovirus, DMV-D10, showed that DCMV is a member of a distinct caulimovirus species, with sequence identities among various ORFs ranging from 25 to 80%.

K. L. Druffel - One of the best experts on this subject based on the ideXlab platform.

  • Genomic characterization of pararetroviral sequences in wild Dahlia spp. in natural habitats
    Archives of virology, 2011
    Co-Authors: Sahar Eid, C. V. Almeyda, D. E. Saar, K. L. Druffel, Hanu R. Pappu
    Abstract:

    The genome structure and organization of endogenous caulimovirus sequences from Dahlia (Dahlia spp), Dahlia mosaic virus (DMV)-D10 from three wild species, D. coccinea (D10-DC), D. sherffii (D10-DS) and D. tenuicaulis (D10-DT), were determined and compared to those from cultivated species of Dahlia, D. variabilis (DvEPRS). The complete ca. 7-kb dsDNA genomes of D10-DC, D10-DS, and D10-DT had a structure and organization typical of a caulimovirus and shared 89.3 to 96.6% amino acid sequence identity in various open reading frames (ORF) when compared to DvEPRS. The absence of the aphid transmission factor and the truncated coat protein fused with the reverse transcriptase ORF were common among these DMV-D10 isolates from wild Dahlia species.

  • Plant pararetroviral sequences in wild Dahlia species in their natural habitats in Mexican mountain ranges
    Plant Pathology, 2010
    Co-Authors: Sahar Eid, D. E. Saar, K. L. Druffel, Hanu R. Pappu
    Abstract:

    Selected wild Dahlia species in their natural habitats from west-central Mexico were tested for the presence of three caulimoviruses known to be associated with cultivated Dahlia (Dahlia variabilis), viz. Dahlia mosaic virus (DMV), DMV-D10 and Dahlia common mosaic virus. Virus species-specific primers and PCR were used followed by cloning and sequencing of the amplicons. Results showed that the wild Dahlia species in their natural habitat contained DMV-D10, which is an endogenous plant pararetrovirus. Viral sequences were found in 91% of the samples (n = 56) representing four different wild species. The gene coding for the movement protein of DMV-D10 from Dahlia coccinea and all other species was cloned and sequenced. Sequence comparisons showed divergence of this gene when compared to that of DMV-D10 from cultivated Dahlias. The discovery of plant pararetroviruses in wild Dahlia species in their natural habitats suggests a possible emergence, co-existence and co-evolution of pararetroviruses and their host plants.

  • Incidence of Multiple and Distinct Species of Caulimoviruses in Dahlia (Dahlia variabilis)
    HortScience, 2009
    Co-Authors: Sahar Eid, K. L. Druffel, Dayle E. Saar, Hanu R. Pappu
    Abstract:

    Dahlia mosaic is a serious disease affecting Dahlias. In addition to the Dahlia mosaic virus (DMV) reported previously, we characterized two putative new caulimoviruses, tentatively designated as DMV-D10 and Dahlia common mosaic virus (DCMV), from Dahlia. To better understand their relative incidence in Dahlia, a total of 213 samples were collected during 2007 and 2008 from several varieties of cultivated Dahlia (D. variabilis) in the United States. Samples were tested for the three caulimoviruses using virus-specific primers in a polymerase chain reaction. Amplicons were cloned and sequenced to confirm the infection of Dahlia with these viruses. Results showed that DMV-D10 was the most prevalent (94%) followed by DCMV (48.5%) and DMV (23%). Mixed infections were common and viruses were detected irrespective of symptom expression at the time of sampling. Two percent of the samples were not infected by any of the three tested caulimoviruses. Results suggest that caulimovirus infections are widespread in Dahlia and highlight the need for testing and production of virus-free material to reduce their spread.

  • Nucleotide sequence and genome organization of a member of a new and distinct Caulimovirus species from Dahlia
    Archives of virology, 2008
    Co-Authors: Hanu R. Pappu, R. Miglino, K. L. Druffel, A. R. Van Schadewijk
    Abstract:

    A distinct caulimovirus, associated with Dahlia mosaic, was cloned and sequenced. The caulimovirus, tentatively designated as Dahlia common mosaic virus (DCMV), had a double-stranded DNA genome of ca. 8 kb. The genome organization of DCMV was found to be typical of members of the genus Caulimovirus and consisted of six major open reading frames (ORFs), ORFs I-VI, and one minor ORF, ORF VII. Sequence comparisons with the DNA genomes of two known caulimoviruses isolated from Dahlia, Dahlia mosaic virus (DMV) and an endogenous caulimovirus, DMV-D10, showed that DCMV is a member of a distinct caulimovirus species, with sequence identities among various ORFs ranging from 25 to 80%.

  • A new and distinct species in the genus Caulimovirus exists as an endogenous plant pararetroviral sequence in its host, Dahlia variabilis
    Virology, 2008
    Co-Authors: Vihanga Pahalawatta, K. L. Druffel, Hanu R. Pappu
    Abstract:

    Abstract Viruses in certain genera in family Caulimoviridae were shown to integrate their genomic sequences into their host genomes and exist as endogenous pararetroviral sequences (EPRV). However, members of the genus Caulimovirus remained to be the exception and are known to exist only as episomal elements in the infected cell. We present evidence that the DNA genome of a new and distinct Caulimovirus species, associated with Dahlia mosaic, is integrated into its host genome, Dahlia ( Dahlia variabilis ). Using cloned viral genes as probes, Southern blot hybridization of total plant DNA from Dahlia seedlings showed the presence of viral DNA in the host DNA. Fluorescent in situ hybridization using labeled DNA probes from the D10 genome localized the viral sequences in Dahlia chromosomes. The natural integration of a Caulimovirus genome into its host and its existence as an EPRV suggests the co-evolution of this plant–virus pathosystem.

J. Ptacek - One of the best experts on this subject based on the ideXlab platform.

  • First Report of Tobacco streak virus on Dahlia in the Czech Republic.
    Plant disease, 2008
    Co-Authors: V. Mokra, B. Gotzova, V. Bezdekova, P. Dedic, J. Ptacek
    Abstract:

    Dahlia is an important ornamental crop in the Czech Republic where they have been grown for more than 150 years. New Dahlia cultivars have been selected by Czech plant breeders. Virus diseases, including mosaic and stunt caused mostly by Dahlia mosaic virus, have been a problem. From 2003 to 2005, color breaking was observed in several Dahlia cultivars of foreign and Czech origin. White stripes in blossoms were most frequently expressed in the second half of the flowering season. No symptoms are visible in flowers of white and yellow cultivars. It was difficult to characterize symptoms on leaves because most cultivars were infected simultaneously by Dahlia mosaic virus. Sap inoculations of Chenopodium quinoa produced local lesions after 5 to 7 days, followed by systemic chlorosis, necrosis of younger leaves, and death of the shoot apex, indicating possible Tobacco streak virus (TSV) infection (2). Spherical particles (25 to 30 nm) were observed in leaf-dip preparations of samples from experimentally infec...

H. R. Pappu - One of the best experts on this subject based on the ideXlab platform.

  • Characterization and comparative analysis of promoters from three plant pararetroviruses associated with Dahlia (Dahlia variabilis)
    Virus Genes, 2015
    Co-Authors: C. V. Almeyda, G. Raikhy, H. R. Pappu
    Abstract:

    Two distinct caulimoviruses, Dahlia mosaic virus (DMV) and Dahlia common mosaic virus (DCMV), and an endogenous plant pararetroviral sequence (DvEPRS, formerly known as DMV-D10) were reported from Dahlia ( Dahlia spp). Promoter elements from these Dahlia-associated pararetroviruses were identified and characterized. The TATA box, the CAAT box, the transcription start site, the polyadenylation signal, and regulation factors, characteristic of caulimovirus promoters, were present in each of these promoter regions. Each of the promoter regions was separately cloned into a binary vector containing β-glucuronidase (GUS) reporter gene and delivered into Agrobacterium tumefaciens by electroporation followed by agroinfiltration into Nicotiana benthamiana . The activity of the 35S promoter homologs was determined by transient expression of the GUS gene both in qualitative and quantitative assays. The length of the promoter regions in DMV, DCMV, and DvEPRS corresponded to 438, 439, and 259 bp, respectively. Quantitative GUS assays showed that the promoters from DMV and DCMV resulted in higher levels of gene expression compared to that of DvEPRS in N. benthamiana leaf tissue. Significant differences were observed among the three promoters ( p  

  • Comparative analysis of endogenous plant pararetroviruses in cultivated and wild Dahlia spp.
    Virus Genes, 2014
    Co-Authors: C. V. Almeyda, D. Saar, M. Samuitiene, H. R. Pappu
    Abstract:

    Two distinct caulimoviruses, Dahlia mosaic virus (DMV) and Dahlia common mosaic virus, and an endogenous plant pararetroviral sequence (DvEPRS) were reported in Dahlia spp. DvEPRS, previously referred to as DMV-D10, was originally identified in the US from the cultivated Dahlia variabilis , and has also been found in New Zealand, Lithuania and Egypt, as well as in wild Dahlia species growing in their natural habitats in Mexico. Sequence analysis of three new EPRSs from cultivated Dahlias from Lithuania [D10-LT; 7,159 nucleotide level (nt)], New Zealand (D10-NZ, 7,156 nt), and the wild species, Dahlia rupicola , from Mexico (D10-DR, 7,133 nt) is reported in this study. The three EPRSs have the structure and organization typical of a caulimovirus species and showed identities among various open reading frames (ORFs) ranging between 71 and 97 % at the nt when compared to those or the known DvEPRS from the US. Examination of a dataset of seven full-length EPRSs obtained to date from cultivated and wild Dahlia spp. provided clues into genetic diversity of these EPRSs from diverse sources of Dahlia. Phylogenetic analyses, mutation frequencies, potential recombination events, selection, and fitness were evaluated as evolutionary evidences for genetic variation. Assessment of all ORFs using phylogenomic and population genetics approaches suggests a wide genetic diversity of EPRSs occurring in Dahlias. Phylogenetic analyses show that the EPRSs from various sources form one clade indicating a lack of clustering by geographical origin. Grouping of various EPRSs into two host taxa (cultivated vs. wild) shows little divergence with respect to their origin. Population genetic parameters demonstrate negative selection for all ORFs, with the reverse transcriptase region more variable than other ORFs. Recombination events were found which provide evolutionary evidence for genetic diversity among Dahlia-associated EPRSs. This study contributes to an increased understanding of molecular population genetics and evolutionary pathways of these reverse transcribing viral elements.

  • Expression of endogenous para-retroviral genes and molecular analysis of the integration events in its plant host Dahlia variabilis
    Virus Genes, 2014
    Co-Authors: H. R. Pappu
    Abstract:

    The Dahlia ( Dahlia variabilis ) genome contains an endogenous pararetrovirus sequence (EPRS) tentatively designated as DvEPRS. The DvEPRS shares genome structure and organization that is typical of members of the Caulimovirus genus. Studies were carried out to better understand the nature of this integration and to determine the gene expression of this DvEPRS. Genomic Southern hybridization showed multiple and random integration events of the DvEPRS in the Dahlia genome. To investigate the presence of DvEPRS transcripts, RT-PCR was done on DNase-treated total RNA from DvEPRS-infected Dahlia plants. Results showed the expression of open reading frames I, V, and VI. Direct PCR from sap extracts produced more intense DNA amplicons of Dahlia mosaic virus and Dahlia common mosaic virus which are believed to exist as typical episomal caulimoviruses, whereas significantly less intense amplicon was seen in case of DvEPRS in comparison with internal transcribed spacer region of Dahlias amplicon. The DvEPRS in wild and cultivated species of Dahlia offer a model system to study the molecular events underlying the ecology, evolution and spread of DvEPRS within natural and managed ecosystems and the factors affecting integration of these EPRS in the plant genome.

  • Biological studies of three caulimoviruses associated with Dahlia (Dahlia variabilis)
    Canadian Journal of Plant Pathology, 2014
    Co-Authors: S. Eid, H. R. Pappu
    Abstract:

    AbstractTwo distinct caulimoviruses, Dahlia mosaic virus (DMV) and Dahlia common mosaic virus (DCMV), were found to be associated with Dahlia mosaic disease. Additionally, an endogenous caulimovirus, Dahlia variabilis endogenous plant pararetroviral sequence (DvEPRS), was found to be present in many cultivated and wild Dahlia spp. Biological properties including mechanical and aphid transmission were investigated for DMV, DCMV and DvEPRS using Verbesina encelioides (crownbeard) as an experimental host. DMV and DCMV were transmitted by Myzus persicae at the rate of 50 and 73%, respectively. DMV and DCMV were mechanically transmissible to V. encelioides and the two effective buffers for mechanical transmission were phosphate buffer (pH 7.0) with nicotinic acid (1%) and sodium bisulfite (5%). Mechanical transmission rates of 58% and 36% were obtained for DMV and DCMV, respectively. DvEPRS was not transmissible by either aphids or mechanical inoculation. Availability of aphid and mechanical inoculation protoc...

  • Caulimoviral sequences in Dahlia variabilis in Egypt
    African Journal of Biotechnology, 2010
    Co-Authors: Aly M. Abdel-salam, Mm Al Khazindar, Sg Eid, H. R. Pappu
    Abstract:

    The presence of Dahlia mosaic virus D10 (DMV-D10) was confirmed for the first time in Dahlia ( Dahlia variabilis ) in Egypt. DMV-D10 was recently described as a caulimovirus that exists as an endogenous pararetroviral sequence (EPRS). DMV-D10 was confirmed by amplification of the ORF1 (encoding for the movement protein) using species specific primers (D10F1/R1). The expected size (900 bp) was amplified from 36 samples with no evidence of infection with either DMV or DCMV. The same Dahlia plants were tested for the presence of CMV, INSV, TSV, and TSWV and they were all negative. Sequence comparisons of the Egyptian DMV-D10 ORF1, GenBank accession HM007162, amplified from these samples revealed that the amplicon had the highest sequence identity (96%) with that of DMV-D10 (isolated from US Dahlia cultivars). Cluster dendogram based on the amino acid sequences of movement protein of all known caulimoviruses placed D10-US (isolated from US Dahlia cultivars), D10 – NZ (isolated from New Zealand Dahlia cultivars), D10-DC (isolated from D. coccinea ) and D10-Egypt (isolated from Egyptian Dahlia cultivars ) in one clade. Key words: Dahlia variabilis, endogenous pararetroviral sequence, DMV-D10.

V. Mokra - One of the best experts on this subject based on the ideXlab platform.

  • First Report of Tobacco streak virus on Dahlia in the Czech Republic.
    Plant disease, 2008
    Co-Authors: V. Mokra, B. Gotzova, V. Bezdekova, P. Dedic, J. Ptacek
    Abstract:

    Dahlia is an important ornamental crop in the Czech Republic where they have been grown for more than 150 years. New Dahlia cultivars have been selected by Czech plant breeders. Virus diseases, including mosaic and stunt caused mostly by Dahlia mosaic virus, have been a problem. From 2003 to 2005, color breaking was observed in several Dahlia cultivars of foreign and Czech origin. White stripes in blossoms were most frequently expressed in the second half of the flowering season. No symptoms are visible in flowers of white and yellow cultivars. It was difficult to characterize symptoms on leaves because most cultivars were infected simultaneously by Dahlia mosaic virus. Sap inoculations of Chenopodium quinoa produced local lesions after 5 to 7 days, followed by systemic chlorosis, necrosis of younger leaves, and death of the shoot apex, indicating possible Tobacco streak virus (TSV) infection (2). Spherical particles (25 to 30 nm) were observed in leaf-dip preparations of samples from experimentally infec...