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Listen to this siteWednesday 16 October 2002
This research project aims to further scientific understanding and improve techniques of gene insertion.
Study Duration : October 1999 to September 2002
Contractor : John Innes Centre
Transformation of the world's major cereal crops is in most cases routine. However, there are still a large number of gaps in our understanding of the exact mechanism of transgene insertion and the possible wider implications for the safety of transgenic crops.
The aim of this project is to develop methods to more fully understand the vector insertion site and its surrounding DNA in transgenic lines of barley, and to assess the occurrence of unintended effects as a result of plant transformation. The project will also develop methods to eliminate marker genes and unwanted vector sequences from transgenic plants.
The main objectives were:
Outcomes
One of the main outcomes of this project was identifying where introduced genes insert into the barley genome.
Interestingly, the pattern of where the genes inserted did not seem to be random. It appeared that the introduced genes were more likely to insert in regions of the barley DNA that contained other expressed genes. The work carried out in this project represents the first time that two different methods of locating (mapping) genes in a genome have been used together to better understand where the introduced genes end up in a crop plant. A second outcome of the project was detailed information on the DNA sequence found next to the inserted genes.
A further outcome of the project was information concerning the suitability of a specific technique, nuclear magnetic resonance (NMR) spectroscopy, for analysing GM plants. This was carried out by comparing the compounds present in the GM plants to those seen in appropriate control plants. From the GM barley lines examined in this part of the study, no differences were found that were specifically due to the insertion of the introduced genes. Some differences were detected, but these were due to the tissue culture and genetic modification process rather than to the presence of the introduced gene. The fact that tissue culture techniques can lead to additional variation in plants developed using a tissue culture step is already well documented.
Finally, in the work on developing methods for producing GM barley without marker genes, significant improvements were made to the existing protocols to produce GM barley where the marker genes may be segregated from the gene of interest in the next generation. It was not possible to confirm that the genes could be segregated within the timescale of the project.
Importance of the results
The results from this research provide important additions to our knowledge of the genetic modification process, in particular a better understanding of the integration of the introduced genes in the barley DNA. This information potentially contributes to refining current safety assessment procedures. The results of the project also suggest that a specific technique (NMR spectroscopy) may be valuable in the analysis of GM material in order to detect unexpected changes in GM plants.
Evaluation of this technique is now continuing in a follow on (G02) programme funded by the Agency. The project has also allowed improvements to be made in the protocols used to produce GM barley and paved the way for the production of marker gene free crop plants. The provision of GM crops that contain only the additional gene of interest may provide reassurance on the long-term safety of these crops in future safety assessments.
Salvo-Garrido H, Travella S, Schwarzacher T, Harwood W A, Snape J W (2001) An efficient method for the physical mapping of transgenes in barley using in situ hybridisation. Genome 44 : 104-110.
Bourdon V, Ladbrooke Z, Wicham A, Lonsdale D, Harwood W (2002) Homozygous transgenic wheat plants with increased luciferase activity do not maintain their high level of expression in the next generation. Plant Science 163 : 297-305.
Harwood W, Ross S M, Bulley S M, Travella S, Busch B, Harden J, Snape J W (2002) Use of the firefly luciferase gene in a barley (Hordeum vulgare) transformation system. Plant Cell Reports DOI 10.1007/s00299-002-0515-3.
Contact
: For any enquiries concerning this research project, please contact the relevant programme contact or email
science@foodstandards.gsi.gov.uk
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