Cauliflower Mosaic Virus (cauliflower + mosaic_virus)

Distribution by Scientific Domains
Life Sciences100%

Terms modified by Cauliflower Mosaic Virus

  • cauliflower mosaic virus 35s promoter
    		•

    Selected Abstracts

    Cauliflower mosaic virus: still in the news

    MOLECULAR PLANT PATHOLOGY, Issue 6 2002
    Muriel Haas
    SUMMARY Taxonomic relationship:Cauliflower mosaic virus (CaMV) is the type member of the Caulimovirus genus in the Caulimoviridae family, which comprises five other genera. CaMV replicates its DNA genome by reverse transcription of a pregenomic RNA and thus belongs to the pararetrovirus supergroup, which includes the Hepadnaviridae family infecting vertebrates. Physical properties:, Virions are non-enveloped isometric particles, 53 nm in diameter (Fig. 1). They are constituted by 420 capsid protein subunits organized following T= 7 icosahedral symmetry (Cheng, R.H., Olson, N.H. and Baker, T.S. (1992) Cauliflower mosaic virus: a 420 subunit (T= 7), multilayer structure. Virology, 16, 655,668). The genome consists of a double-stranded circular DNA of approximately 8000 bp that is embedded in the inner surface of the capsid. Figure 1. Electron micrograph of CaMV virions. Courtesy of J. Menissier de Murcia, Ecole Supérieure de Biotechnologie de Strasbourg. Viral proteins: The CaMV genome encodes six proteins, a cell-to-cell movement protein (P1), two aphid transmission factors (P2 and P3), the precursor of the capsid proteins (P4), a polyprotein precursor of proteinase, reverse transcriptase and ribonuclease H (P5) and an inclusion body protein/translation transactivator (P6). Hosts: The host range of CaMV is limited to plants of the Cruciferae family, i.e. Brassicae species and Arabidopsis thaliana, but some viral strains can also infect solanaceous plants. In nature, CaMV is transmitted by aphids in a non-circulative manner. [source]

    Consistent transcriptional silencing of 35S-driven transgenes in gentian

    THE PLANT JOURNAL, Issue 4 2005
    Kei-ichiro Mishiba
    Summary In this study, no transgenic gentian (Gentiana triflora × Gentiana scabra) plants produced via Agrobacterium -mediated transformation exhibited transgene (GtMADS, gentian-derived MADS-box genes or sGFP, green fluorescent protein) expression in their leaf tissues, despite the use of constitutive Cauliflower mosaic virus (CaMV) 35S promoter. Strikingly, no expression of the selectable marker gene (bar) used for bialaphos selection was observed. To investigate the possible cause of this drastic transgene silencing, methylation-specific sequences were analysed by bisulfite genomic sequencing using tobacco transformants as a control. Highly methylated cytosine residues of CpG and CpWpG (W contains A or T) sites were distinctively detected in the promoter and 5, coding regions of the transgenes 35S- bar and 35S- GtMADS in all gentian lines analysed. These lines also exhibited various degrees of cytosine methylation in asymmetrical sequences. The methylation frequencies in the other transgene, nopaline synthase (NOS) promoter-driven nptII, and the endogenous GtMADS gene coding region, were much lower and were variable compared with those in the 35S promoter regions. Transgene methylation was observed in the bialaphos-selected transgenic calluses expressing the transgenes, and methylation sequences were distributed preferentially around the as-1 element in the 35S promoter. Calluses derived from leaf tissues of silenced transgenic gentian also exhibited transgene suppression, but expression was recovered by treatment with the methylation inhibitor 5-aza-2,-deoxycytidine (aza-dC). These results indicated that cytosine methylation occurs exclusively in the 35S promoter regions of the expressed transgenes during selection of gentian transformants, causing transcriptional gene silencing. [source]

    Bioreactor strategies for improving production yield and functionality of a recombinant human protein in transgenic tobacco cell cultures

    BIOTECHNOLOGY & BIOENGINEERING, Issue 2 2009
    Ting-Kuo Huang
    Abstract Plant cell culture production of recombinant products offers a number of advantages over traditional eukaryotic expression systems, particularly if the product can be targeted to and purified from the cell culture broth. However, one of the main obstacles is product degradation by proteases that are produced during cell culture, and/or the loss of biological activity of secreted (extracellular) products as a result of alteration in the protein conformation. Because proteolysis activity and target protein stability can be significantly influenced by culture conditions, it is important to evaluate bioprocess conditions that minimize these effects. In this study, a bioreactor strategy using a protocol involving pH adjustment and medium exchange during plant cell culture is proposed for improving the production of functional recombinant ,1 -antitrypsin (rAAT), a human blood protein, produced using several alternative expression systems, including a Cauliflower mosaic virus (CaMV) 35S constitutive promoter expression system, a chemically inducible, estrogen receptor-based promoter (XVE) expression system, and a novel Cucumber mosaic virus (CMV) inducible viral amplicon (CMViva) expression system developed by our group. We have demonstrated that higher medium pH help reduce protease activity derived from cell cultures and improve the inherent stability of human AAT protein as well. This strategy resulted in a fourfold increase in the productivity of extracellular functional rAAT (100 µg/L) and a twofold increase in the ratio of functional rAAT to total rAAT (48%) in transgenic N. benthamiana cell cultures using a chemically inducible viral amplicon expression system. Biotechnol. Bioeng. 2009;102: 508,520. © 2008 Wiley Periodicals, Inc. [source]

    Pararetrovirus,crucifer interactions: attack and defence or modus vivendi?

    MOLECULAR PLANT PATHOLOGY, Issue 1 2000
    Simon N. Covey
    The compatible infection of plants by viruses usually leads to the development of systemic symptoms. Symptom expression of this kind is generally understood to be a host response that indicates an inability of the host to defend itself from attack. We have been studying compatible interactions between the plant pararetrovirus cauliflower mosaic virus (CaMV) and its crucifer hosts in order to understand the relationship between viral activity, symptom expression and plant defence. A CaMV protein (P6) appears to play a major role in eliciting symptom expression. This host response leads to a regulation of the viral multiplication cycle that is associated with leaf mosaics. The host regulation of CaMV appears to operate at the transcriptional level through an effect on the 35S promoter, or at the post-transcriptional level by a process that is akin to gene silencing, and can lead to host recovery depending upon the genetic background of the host. The plant apex is a focus for antiviral defence mechanisms, presumably because viral infection of the apical meristem would rapidly compromise the ability of the plant to generate new leaves and flowers for reproduction. The balance of interactions between CaMV and crucifers can provide a sustainable source of host plants to ensure viral propagation and viral exposure allows the host to adapt and develop its repertoire of defence mechanisms. [source]

    Differential regulation of TGA transcription factors by post-transcriptional control

    THE PLANT JOURNAL, Issue 5 2002
    Dominique Pontier
    Summary Transcription factors often belong to multigene families and their individual contribution in a particular regulatory network remains difficult to assess. We show here that specific members from a family of conserved Arabidopsis bZIP transcription factors, the TGA proteins, are regulated in their protein stability by developmental stage-specific proteolysis. Using GFP fusions of three different Arabidopsis TGA factors that represent members of distinct subclasses of the TGA factor family, we demonstrate that two of these TGA proteins are specifically targeted for proteolysis in mature leaf cells. Using a supershift gel mobility assay, we found evidence for similar regulation of the cognate proteins as compared to the GFP fusion proteins expressed under the cauliflower mosaic virus (CaMV) 35S promoter. Using various inhibitors, we showed that the expression of at least one of these three TGA factors could be stabilized by inhibition of proteasome-mediated proteolysis. This study indicates that TGA transcription factors may be regulated by distinct pathways of targeted proteolysis that can serve to modulate the contribution of specific members of a multigene family in complex regulatory pathways. [source]