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Listen to this siteWednesday 16 October 2002
This research project will compare different strains of GM wheat and barley seed by using the latest scientific methods.
Study Duration : September 2001 to January 2005
Contractor : John Innes Centre
Wheat and Barley provide major sources of protein and carbohydrates for human and animal nutrition. They are attractive targets for genetic modification because of the possibility of modifying bread-making characteristics in wheat and malting quality in barley. In genetically modifying such traits, transgene expression is usually targeted to the seed. The seed is the part of the part that is usually incorporated into numerous foodstuffs, therefore this project examines techniques that could detect unexpected effects of the transgene insertion in GM wheat and barley seed.
In the project, existing well characterised transgenic lines of wheat and barley will be analysed using a range of techniques to detect variation due to the transgene insertion. The methods to be used will include examination of the major seed storage proteins using PAGE (Poly-acrylamide gel electrophoresis), metabolite profiling using NMR techniques and also SAGE (serial analysis of gene expression) technology to look at changes in gene expression. By examining the same transgenic lines using a range of methods it should be possible to make recommendations as to the best approaches for use in food safety assessments.
This project assessed the suitability of several analytical methods, such as Poly-Acrylamide Gel Electrophoresis (PAGE), metabolite profiling and novel techniques such as Serial Analysis of Gene Expression technology (SAGE), and junction analysis, which may be used in the safety assessment of genetically modified wheat and barley. The techniques were applied to the same GM wheat and barley material, enabling researchers to compare the techniques in terms of sensitivity, reliability and suitability in different plant species.
All methods used in the study demonstrated the potential to be used in the safety assessment of genetically modified foods. Nuclear Magnetic Resonance (NMR) was particularly suitable for high throughput screening, providing detailed information about the chemical composition of the extracts from wheat and barley seed.
Analysis of junction sequences showed that in most of the transgenic lines that were selected, insertion had occurred in gene rich regions and had led to gene disruption. None of the barley lines had any DNA from outside of the T-DNA at the right border whereas five out of the eight wheat lines did have extraneous DNA.
Transcript analysis was undertaken on only a limited sub-set of the transgenic lines. SAGE showed that in one line there was 58 genes whose expression was up- or down-regulated more than 5-fold. Use of Affymetrix arrays with two other lines did not identify any significant changes in gene expression except for identifying the expression of the inserted gene. Analysis of seed storage proteins showed changes in the levels of all detected proteins in some lines and changes in individual proteins in other lines. These changes are not considered significant in the context of food safety.
Metabolomic analysis using NMR showed that, there are far greater differences between the unmodifed lines compared to wild type controls, than when the unmodified lines are compared with the transgenic lines. Thus changes induced by plant tissue culture accounts for most of the metabolomic changes rather than the transgenes themselves. The ploidy of the host genome could influence the extent of the changes seen in transgenic plants since the changes observed in hexaploid wheat were far less than those seen in diploid barley.
The final report is available from the FSA Information centre.
To obtain a copy, please contact the Enquiry Desk, Information Services, Food Standards Agency (tel: 020 7276 8181/8182 or email:
library&info@foodstandards.gsi.gov.uk
)
The following paper has also been published from this project:
Salvo G H, Travella S, Bilham L J, Harwood W A, Snape J W (2004) The distribution of transgene insertion sites in barley determined by physical and genetic mapping. Genetics , 167 : 1371-1379.
Contact
:
Email
: science@foodstandards.gsi.gov.uk
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