|Molecular Plant Biotechnology|
|Viral Vectors, Molecular Farming, Biofuels, Bionanoparticles|
42B, Room 154
Phone: 0049 241 8028131
Fax: 0049 241 871062
Plant viruses are usually viewed as dangerous, undesirable pathogens. Their genomes however provide useful 'designer functions' or 'sequence modules' which can be utilized to create future gene vectors for plant or general biotechnology. Regulatory sequences derived from plant viral genomes have already been efficiently used to control expression of foreign genes in vivo. The development of plant virus-based vectors for the expression of foreign proteins has created a major impact on commercial biotechnology, biomedical research and other areas of life sciences. The attractiveness of using plant viral vectors to express foreign proteins in plants has been motivated by the potential economic advantages available through inexpensive, high-level expression of valuable proteins in systems capable of producing high yields of biomass at relatively low input costs. Further benefits include rapid and convenient engineering coupled with flexibility for immediate application in various plant species. These characteristics become advantageous when very high levels of gene expression are needed within a short time.
Similar to the viral vector system, transient gene expression via agroinfiltration is a fast, flexible and reproducible approach to high-level expression of useful proteins. Here recombinant strains of Agrobacterium tumefaciens can be used for transientexpression of genes that have been inserted into the T-DNA region of the bacterial Ti plasmid. However, the utility of the system is limited because the ectopic protein expression ceases after 2-3 days. In many cases post-transcriptional gene silencing (PTGS) is a major cause for this lack of efficiency.
A system based on co-expression of a viral-encoded suppressor protein which originally represents a viral adaptation to a novel host antiviral defense via gene silencing. The suppressor proteins of different viruses, are analysed for their ability to prevent the onset of post-transcriptional gene silencing in the infiltrated tissues and thus allow high level of transient expression. Due to its simplicity and efficiency, we anticipate that this silencing suppressor co-expression system will have value in industrial production as well as a research tool for isolation and biochemical characterisation of a broad range of proteins without the need for the time-consuming regeneration of stably transformed plants.
Recombinant plant viruses have started to make an impact as safer alternative vaccines to the use of bacterial and attenuated animal viruses: the latter both require propagation in costly cell-culture systems where they can undergo reversion towards a virulent form and/or become contaminated by other pathogens. Plant virus-based vectors can be multiplied cheaply and to high yields in host plants.The chimeric virus particles possess the antigenic properties of the inserted sequences and it has been shown that the inserted epitopes are immunogenic in animals. These results demonstrate that plant viruses can be used as a high-yielding system for the presentation of foreign peptide sequences.
Antibody-mediated resistencePlant diseases are a major threat to the world food supply, as up to 15% of production is lost to pathogens. In the past, disease control and the generation of resistant plant lines protected against viral, bacterial or fungal pathogens, was achieved using conventional breeding based on crossings, mutant screenings and backcrossing. Many approaches in this field have failed or the resistance obtained has been rapidly broken by the pathogens. Recent advances in molecular biotechnology have made it possible to obtain and to modify genes that are useful for generating disease resistant crops. Antibody-based resistance is a novel strategy for generating transgenic plants resistant to pathogens. Decades ago it was shown that polyclonal and monoclonal antibodies can neutralize viruses, bacteria and selected fungi. This approach has been improved recently by the development of recombinant antibodies (rAbs). Crop resistance can be engineered by the expression of pathogen-specific antibodies, antibody fragments or antibody fusion proteins. The advantages of this approach are that rAbs can be engineered against almost any target molecule, and it has been demonstrated that expression of functional pathogen-specific rAbs in plants confers effective pathogen protection. The efficacy of antibody-based resistance was first shown for plant viruses and its application to other plant pathogens is becoming more established. However, successful use of antibodies to generate plant pathogen resistance relies on appropriate target selection, careful antibody design, efficient antibody expression, stability and targeting to appropriate cellular compartments. The evaluation of strategies to adapt and efficiently test this technique for the specialized replication and genome expression strategies of geminiviruses is in progress.
Nanoparticles are promising platforms for the diagnosis and treatment of cancer. Diverse classes and shapes of materials have been investigated to establish design principles that achieve the effective partitioning of medical cargos between tumors and healthy tissues. Molecular targeting strategies combined with specific nanoparticle shapes confer tissue-specificity on the carriers, allowing the cell-specific delivery of cargos. We recently developed a filamentous platform technology in which the plant virus Potato virus X (PVX) was used as a scaffold.
Activities within the Cluster of Excellence "Tailor-Made Fuels from Biomass"
Dr. Megan Garvey
Phone: 0049-241 80-28317
Megan is investigating cellulase activity in the production of biofuels. Her focuses include: recombinant cellulase expression systems, increasing cellulase activity through enzyme synergism and the production of tailor-made cellulosomes.
Dr. Camilla Lambertz
Phone: 0049-241 80-28317
Camilla is working on the identification of suitable genes which code for ligninolytic enzymes. The challenge is to create an enzyme cocktail which can be used in lignin degradation and, finally, in an optimized utilization of wood for biofuel additivies.