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Xueping Zhou – One of the best experts on this subject based on the ideXlab platform.

  • Etiology of Ageratum Yellow Vein Diseases in South China.
    Plant disease, 2013
    Co-Authors: Xiaoyang Jiao, Huanran Gong, Liu Xuejian, Yan Xie, Xueping Zhou
    Abstract:

    Ageratum conyzoides is a common weed in agricultural regions in Asia. A. conyzoides plants exhibiting yellow vein symptoms were collected from Yunnan and Guangxi provinces of China. Polymerase chain reaction detection and sequence analysis showed that samples collected from Yunnan were mainly infected by Tobacco curly shoot virus (TbCSV) associated with Ageratum yellow vein China betasatellite (AYVCNB), while samples from Guangxi were mostly infected by Papaya leaf curl China virus (PaLCuCNV) and AYVCNB, or by Ageratum yellow vein China virus (AYVCNV) and AYVCNB, with a few exhibiting dual infections by PaLCuCNV, AYVCNV, and AYVCNB. Agrobacterium-mediated inoculation of infectious clones showed that both TbCSV and AYVCNB or PaLCuCNV and AYVCNB produced typical yellow vein symptoms in A. conyzoides. Consequently, Ageratum yellow vein diseases in Yunnan and Guangxi provinces were caused by TbCSV/AYVCNB, PaLCuCNV/AYVCNB, or AYVCNV/ AYVCNB. The implications of these results in relation to the prevalence of begomoviruses in cultivated plants are discussed.

  • Ageratum yellow vein China virus is a distinct begomovirus species associated with a DNAβ molecule
    Phytopathology, 2007
    Co-Authors: Qing Xiong, Sanwei Fan, Xueping Zhou
    Abstract:

    ABSTRACT Ageratum conyzoides plants exhibiting yellow vein symptoms, collected near Haikou, Hainan Province, China, contained begomoviral DNA-A-like molecules. The complete sequences of the molecules from two samples, Hn2 and Hn2-19, were shown to consist of 2,768 and 2,748 nucelotides (nt), respectively. These sequences have more than 97% nucleotide sequence identity, but less than 86% identity with other reported begomovirus sequences. In line with the taxonomic convention for begomoviruses, Hn2 and Hn2-19 are therefore considered to represent isolates of a distinct begomovirus species, for which the name Ageratum yellow vein China virus (AYVCNV) is proposed. Sequence alignment shows AYVCNV has arisen by recombination among viruses related to Ageratum yellow vein virus, Papaya leaf curl China virus, and an unidentified begomovirus. Southern blot analyses revealed that all plants sampled contained molecules resembling DNAβ. DNAβ molecules from three samples were 1,323 or 1,324 nt long and had >98% sequen…

Masato Ikegami – One of the best experts on this subject based on the ideXlab platform.

  • Pepper yellow leaf curl Indonesia virus, a new bipartite begomovirus species that belongs to distinct clade of Old World geminiviruses
    Nature Precedings, 2010
    Co-Authors: Pradeep Sharma, Yutaka Shibuya, J. Sakata, Masato Ikegami
    Abstract:

    Begomoviruses are currently emerging as a major threat to vegetable production in many tropical and subtropical regions worldwide. Pepper yellow leaf curl disease (PepYLCD) has been noticed in many Capsicum annum L. producing regions from East Asia especially from Indonesia and causes devastating damage to pepper crop production since 2000. In this study we have cloned and sequenced complete nucleotide of begomoviruses from pepper exhibiting leaf curling and bright yellowing symptoms. Besides, we also determined the occurrence of disease on tomato evoking leaf curl symptoms and Ageratum with yellow vein type of symptoms. On the basis of genome organization and sequence homology, these viruses were designated as Pepper yellow leaf curl Indonesia virus (PeYLCIV)- new species followed by its two new starins i.e. PeYLCIV-Tomato and PeYLCIV-Ageratum. These viruses have bipartite genomes. Pepper virus DNAs from Indonesia (PepYLCIV, PepYLCIV-Tomato and PepYLCIV-Ageratum DNA-As) were noticeably distinct, forming a separate branch from the other viruses infecting pepper. A considerable divergence is observed in the common region (CR) of the genomic components of PeYLCIV (77%), PeYLCIV-Tomato (82%) and PeYLCIV-Ageratum (75%). A stem-loop forming region and Rep-binding motif are identical in CRs of three viruses. CR of PepYLCIV-Ageratum DNA-A is approximately 10 nucleotides longer than those of PepYLCIV DNA-A and PepYLCIV-Tomato DNA-A. Similar insertion is also found in the common region of PepYLCIV-Ageratum DNA-B. PeYLCIV DNA-A alone is infectious in pepper and N. benthamiana plants and association with DNA-B increases symptom severity.

  • Strains of a new bipartite begomovirus, pepper yellow leaf curl Indonesia virus, in leaf-curl-diseased tomato and yellow-vein-diseased Ageratum in Indonesia
    Archives of Virology, 2008
    Co-Authors: Jyun-ji Sakata, Yutaka Shibuya, Pradeep Sharma, Masato Ikegami
    Abstract:

    The complete nucleotide sequences of begomoviruses from pepper with leaf curl and yellowing symptoms, tomato with leaf curl symptoms, and Ageratum with yellow vein in Indonesia were determined. On the basis of genome organization and sequence homology, they were proposed to belong to a new species, Pepper yellow leaf curl Indonesia virus (PepYLCIV), which includes the new strains PepYLCIV-Tomato and PepYLCIV-Ageratum. These viruses had bipartite genomes. Pepper virus DNAs from Indonesia (PepYLCIV, PepYLCIV-Tomato and PepYLCIV-Ageratum DNA-As) were noticeably distinct, forming a separate branch from the viruses infecting pepper. Considerable divergence was observed in the common region (CR) of the genomic components of PepYLCIV (77%), PepYLCIV-Tomato (82%) and PeYLCIV-Ageratum (75%). A stem-loop-forming region and a Rep-binding motif were identical in the CR of the three viruses. The CRs of PepYLCIV-Ageratum DNA-A was approximately 10 nucleotides longer than that of PepYLCIV DNA-A and PepYLCIV-Tomato DNA-A. A similar insertion was also found in the CR of PepYLCIV-Ageratum DNA-B. PepYLCIV DNA-A alone was infectious in pepper and Nicotiana benthamiana plants, and association with DNA-B increased symptom severity.

  • A begomovirus associated with Ageratum yellow vein disease in Indonesia: evidence for natural recombination between tomato leaf curl Java virus and Ageratum yellow vein virus-[Java]
    Archives of virology, 2007
    Co-Authors: T. Kon, K. Kuwabara, Sri Hendrastuti Hidayat, Masato Ikegami
    Abstract:

    A begomovirus (2747 nucleotides) and a satellite DNAβ component (1360 nucleotides) have been isolated from Ageratum conyzoides L. plants with yellow vein symptoms growing in Java, Indonesia. The begomovirus is most closely related to Tomato leaf curl Java virus (ToLCJV) (91 and 98% in the total nucleotide and coat protein amino acid sequences, respectively), although the products of ORFs C1 and C4 are more closely related to those of Ageratum yellow vein virus-[Java] (91 and 95% identity, respectively). For this reason, the begomovirus it is considered to be a strain of ToLCJV and is referred to as ToLCJV-Ageratum. The virus probably derives from a recombination event in which nucleotides 2389–2692 of ToLCJV have been replaced with the corresponding region of the AYVV-[Java] genome, which includes the 5′ part of the intergenic region and the C1 and C4 ORFs. Infection of A. conyzoides with ToLCJV-Ageratum alone produced no symptoms, but co-infection with DNAβ induced yellow vein symptoms. Symptoms induced in Nicotiana benthamiana by ToLCJV-Ageratum, ToLCJV and AYVV-[Java] are consistent with the exchange of pathogenicity determinant ORF C4 during recombination.

John Stanley – One of the best experts on this subject based on the ideXlab platform.

  • The DNA β satellite component associated with Ageratum yellow vein disease encodes an essential pathogenicity protein (βC1)
    Virology, 2004
    Co-Authors: Keith Saunders, Alexandra Norman, Sebastien Gucciardo, John Stanley
    Abstract:

    Ageratum yellow vein disease (AYVD) is caused by the geminivirus Ageratum yellow vein virus (AYVV) and an associated DNA beta satellite. We have mapped a DNA beta transcript to a highly conserved open reading frame (betaC1 ORF). The most abundant transcript 5′-terminus is located 8 bases upstream of the betaC1 ORF putative initiation codon while the transcript terminates at multiple sites downstream from the putative termination codon. Disruption of betaC1 protein expression by the introduction of an internal nonsense codon prevented infection of the AYVV-satellite complex in Ageratum and altered the phenotype in Nicotiana benthamiana to that produced by AYVV alone although the mutant was maintained in systemically infected tissues. Modification of the putative initiation codon to a nonsense codon produced an intermediate phenotype in N. benthamiana and a mild yellow vein phenotype in Ageratum, suggesting that betaC1 protein expression could be initiated from an alternative site. N. benthamiana plants containing a dimeric DNA beta transgene produced severe developmental abnormalities, vein-greening, and cell proliferation in the vascular bundles. Expression of betaC1 protein from a potato virus X (PVX) vector also induced abnormal plant growth. Our results demonstrate that the satellite encodes at least one protein that plays a major role in symptom development and is essential for disease progression in Ageratum, the natural host of the AYVD complex.

  • Association of a Begomovirus and Nanovirus-like Molecule with Ageratum Yellow Vein Disease in Pakistan.
    Plant disease, 2000
    Co-Authors: Shahid Mansoor, John Stanley, Habibullah Khan, Mazhar Hussain, Yusuf Zafar, Marion S. Pinner, Rob W. Briddon, Peter G. Markham
    Abstract:

    Whitefly-transmitted geminiviruses (begomoviruses) cause heavy losses to many food and fiber crops in Pakistan. Many weeds also show symptoms typical of begomoviruses. Ageratum (Ageratum conyzoides) is a common perennial weed in Pakistan, growing along irrigation canals, that often shows symptoms, such as yellow vein and mosaic, suggesting infection by a begomovirus. To confirm this, symptomatic and asymptomatic Ageratum plants were collected from three locations in the Punjab Province of Pakistan, and total DNA was isolated, subjected to agarose gel electrophoresis, transferred to a nylon membrane, and Southern blotted. Total DNA isolated from cotton infected with Cotton leaf curl virus (CLCuV), tomato infected with Tomato leaf curl virus from Pakistan (TLCV-Pak), tobacco infected with African cassava mosaic virus (ACMV) from Nigeria, and healthy tobacco were included as controls. A full-length clone of CLCuV DNA A was labeled with [32P]dCTP by oligo-labeling and hybridized at medium stringency. The prob…

  • Novel defective interfering DNAs associated with Ageratum yellow vein geminivirus infection of Ageratum conyzoides.
    Virology, 1997
    Co-Authors: John Stanley, Keith Saunders, Marion S. Pinner, Sek-man Wong
    Abstract:

    Defective DNA forms of the geminivirus Ageratum yellow vein virus (AYVV) have been identified in naturally infected Ageratum conyzoides plants. Several examples of the defective DNA have been cloned from purified virus-specific supercoiled DNA and characterized by sequence analysis. All are approximately half the size of AYVV genomic DNA, and all contain intergenic region sequences and the 5′ terminus of gene C1 as well as additional sequences that are unrelated to the viral genomic DNA. The chimeric nature of the defective DNA distinguishes it from previously characterized geminivirus defective and satellite DNAs. The defective DNA ameliorates disease symptoms and causes a significant delay in the accumulation of viral DNA during the early stage of infection when coinoculated with the AYW genomic DNA into Nicotiana benthamiana, suggesting a biological role as a defective interfering DNA.

Messanvi Gbeassor – One of the best experts on this subject based on the ideXlab platform.

  • in vivo and in vitro toxicological evaluation of the hydroalcoholic leaf extract of Ageratum conyzoides l asteraceae
    Journal of Ethnopharmacology, 2014
    Co-Authors: Aboudoulatif Diallo, Koffi Amegbor, Amegnona Agbonon, Kodjo Aklikokou, Edmond E. Creppy, Kwashie Eklugadegbeku, Messanvi Gbeassor
    Abstract:

    Abstract Ethnopharmacological relevance In African traditional medicine, Ageratum conyzoides has been used as purgative, febrifuge, anti-ulcer and wound dressing. To date there is no safety information about long term use of Ageratum conyzoides which contains pyrrolizidine alkaloids, a class of hepatotoxic and carcinogenic phytochemicals. This study aims to evaluate the 90 days subchronic toxicity and in vitro toxicity of Ageratum conyzoides. Materials and methods Three groups of 8 rats (4 males and 4 females) received distilled water (control), 500 and 1000 mg/kg of the extract daily for 90 consecutive days by oral gavage. The animals were observed daily for abnormal clinical signs and death. Body weight, relative organ weight, haematological and biochemical parameters of blood as well as heart, kidney, liver and spleen tissues histology were evaluated. Results After 90 days administration, Ageratum conyzoides increased significantly (p Conclusions Our results have shown that Ageratum conyzoides at 500 and 1000 mg/kg can induce liver, kidney and haematological disorders. These toxics effects can be attributed to its total alkaloids especially to pyrrolizidine alkaloids which are present in this plant.

  • In vivo and in vitro toxicological evaluation of the hydroalcoholic leaf extract of Ageratum conyzoides L. (Asteraceae).
    Journal of ethnopharmacology, 2014
    Co-Authors: Aboudoulatif Diallo, Kwashie Eklu-gadegbeku, Koffi Amegbor, Amegnona Agbonon, Kodjo Aklikokou, Edmond E. Creppy, Messanvi Gbeassor
    Abstract:

    In African traditional medicine, Ageratum conyzoides has been used as purgative, febrifuge, anti-ulcer and wound dressing. To date there is no safety information about long term use of Ageratum conyzoides which contains pyrrolizidine alkaloids, a class of hepatotoxic and carcinogenic phytochemicals. This study aims to evaluate the 90 days subchronic toxicity and in vitro toxicity of Ageratum conyzoides. Three groups of 8 rats (4 males and 4 females) received distilled water (control), 500 and 1000 mg/kg of the extract daily for 90 consecutive days by oral gavage. The animals were observed daily for abnormal clinical signs and death. Body weight, relative organ weight, haematological and biochemical parameters of blood as well as heart, kidney, liver and spleen tissues histology were evaluated. After 90 days administration, Ageratum conyzoides increased significantly (p<0.05) the relative weight of the liver, the spleen and kidney as compared to control group. Ageratum conyzoides increased also significantly (p<0.05) ALP, ALT, AST and blood glucose. Furthermore, an increase in the number of platelets associated with a normocytic and normochromic anaemia was observed. The cytotoxicity, determined by the MTT test and neutral red assay, has shown that the cytotoxicity of hydroalcoholic extract of Ageratum conyzoides and its total alkaloids was very close. Our results have shown that Ageratum conyzoides at 500 and 1000 mg/kg can induce liver, kidney and haematological disorders. These toxics effects can be attributed to its total alkaloids especially to pyrrolizidine alkaloids which are present in this plant. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Keith Saunders – One of the best experts on this subject based on the ideXlab platform.

  • The DNA β satellite component associated with Ageratum yellow vein disease encodes an essential pathogenicity protein (βC1)
    Virology, 2004
    Co-Authors: Keith Saunders, Alexandra Norman, Sebastien Gucciardo, John Stanley
    Abstract:

    Ageratum yellow vein disease (AYVD) is caused by the geminivirus Ageratum yellow vein virus (AYVV) and an associated DNA beta satellite. We have mapped a DNA beta transcript to a highly conserved open reading frame (betaC1 ORF). The most abundant transcript 5′-terminus is located 8 bases upstream of the betaC1 ORF putative initiation codon while the transcript terminates at multiple sites downstream from the putative termination codon. Disruption of betaC1 protein expression by the introduction of an internal nonsense codon prevented infection of the AYVV-satellite complex in Ageratum and altered the phenotype in Nicotiana benthamiana to that produced by AYVV alone although the mutant was maintained in systemically infected tissues. Modification of the putative initiation codon to a nonsense codon produced an intermediate phenotype in N. benthamiana and a mild yellow vein phenotype in Ageratum, suggesting that betaC1 protein expression could be initiated from an alternative site. N. benthamiana plants containing a dimeric DNA beta transgene produced severe developmental abnormalities, vein-greening, and cell proliferation in the vascular bundles. Expression of betaC1 protein from a potato virus X (PVX) vector also induced abnormal plant growth. Our results demonstrate that the satellite encodes at least one protein that plays a major role in symptom development and is essential for disease progression in Ageratum, the natural host of the AYVD complex.

  • Novel defective interfering DNAs associated with Ageratum yellow vein geminivirus infection of Ageratum conyzoides.
    Virology, 1997
    Co-Authors: John Stanley, Keith Saunders, Marion S. Pinner, Sek-man Wong
    Abstract:

    Defective DNA forms of the geminivirus Ageratum yellow vein virus (AYVV) have been identified in naturally infected Ageratum conyzoides plants. Several examples of the defective DNA have been cloned from purified virus-specific supercoiled DNA and characterized by sequence analysis. All are approximately half the size of AYVV genomic DNA, and all contain intergenic region sequences and the 5′ terminus of gene C1 as well as additional sequences that are unrelated to the viral genomic DNA. The chimeric nature of the defective DNA distinguishes it from previously characterized geminivirus defective and satellite DNAs. The defective DNA ameliorates disease symptoms and causes a significant delay in the accumulation of viral DNA during the early stage of infection when coinoculated with the AYW genomic DNA into Nicotiana benthamiana, suggesting a biological role as a defective interfering DNA.