www.checkbiotech.org ; www.raupp.info ; www.czu.cz

GE risk assessment in the European Union, November 2006 by Louise VT
Shepherd & Howard V Davies.

Prior to market approval in Europe, genetically engineered (GE) crops and
products undergo a rigorous risk safety assessment based on a comparative
approach. That approach assesses differences between the GEO and its derived
products and their non-GE counterparts, the counterparts having a history of
safe use (1,2).


The risk assessment focuses on a range of parameters, which are described
in the European Food Safety Authority (EFSA) guidance document (2).
Compositional analysis is one of these parameters and the OECD (Organization
for Economic Co-operation and Development) is providing guidance on which
compounds should be targeted for analysis on a crop by crop basis. The
analysis takes into account the crop-specific profile of compounds with
nutritional or anti-nutritional characteristics. Significant intentional or
unintentional changes in such compounds are likely to drive the need for
more detailed risk assessment (3,4).

If a trait or traits are introduced with the intention of modifying
composition significantly, and where the degree of equivalence cannot be
considered substantial, then the safety assessment of characteristics other
than those derived from the introduced trait(s) becomes of greater
importance. Whilst the potential for using modern transcriptomic, proteomic,
and metabolomic approaches to assess the potential for detecting unintended
effects is under evaluation (e.g., the EU "SAFEFOODS" project
[http://www.safefoods.nl]), the targeted analysis of key nutrients and
anti-nutrients remains the cornerstone of the compositional evaluations (1).

GE potato as a case study for compositional analysis

Potatoes are the world?s fourth most important food crop and have long been
used as a model crop for studies on gene function using
Agrobacterium-mediated transformations. The cultivated potato has complex
genetics (it is tetraploid), and genetic engineering approaches that add
value to existing varieties with a strong pedigree in other characteristics
remain attractive scientifically.

The Scottish Crop Research Institute (http://www.scri.sari.ac.uk) has a
history of producing a range of GE potatoes for experimental purposes; this
has afforded opportunities to develop projects on the use of metabolomics to
assess the potential for unintended effects.

We feel it is important, however, to use existing OECD guidelines to
establish the baseline against which data on metabolomics can be compared.
In its 2002 "Consensus Document on Compositional Considerations for New
Varieties of Potatoes: Key Food and Feed Nutrients, Anti-nutrients and
Toxicants," the OECD (5) considers that if the analyses of specific
compositional parameters listed in their document indicate that a novel
variety falls within the ranges found in the literature (apart from
intentional modifications resulting from transgenic approaches) then the
variety can be considered equivalent with respect to its overall
composition. In our experiment, metabolite analysis included soluble
carbohydrates, glycoalkaloids, vitamin C, total nitrogen, and fatty acids.
Trypsin inhibitor activity was also assayed. These are the major compounds
recommended by the OECD in its 2002 consensus document.

Range of GE potatoes included

Using (primarily) the potato variety Desirée, the study included transgenic
modifications to a range of metabolic and development processes, including
primary carbohydrate metabolism, polyamine biosynthesis, and glycoprotein
processing. The lines included some with extreme phenotypes, e.g., those
with a modified glycoprotein processing protein [see ref. 6], which produces
stunted plants with poor tuber yield and modified leaf anatomy. Other lines
overexpressed a gene that encodes S-adenosylmethionine decarboxylase
(modified polyamine metabolism) and showed significant increases in tuber
number [see ref. 7], whilst yet another group of transgenics contained
starch with amylose levels reduced by 90% (unpublished). All experiments
included appropriate controls consisting of a) wild type non-GE tubers, b)
non-GE tubers produced from plants regenerated through tissue culture
(including a callus phase), and c) GE tubers derived from transformation
with an ?empty vector?, i.e., no specific target gene included (with the
exception of the kanamycin resistance gene as a selectable marker).

What unintended effects were observed?

In general the targeted compositional analysis revealed no consistent
differences between GE lines and respective controls. No construct
specifically induced unintended effects. Statistically significant
differences between wild type controls and specific GE lines did occur but
appeared to be random and not associated with any specific genetic
construct. Indeed such significant differences were also found between wild
types and both non-GE, tissue culture derived, and GE tubers derived from
transformation with the empty vector. More specifically, the study revealed
a consistent and significant increase in vitamin C and a decrease in
glycoalkaloids across many of the GE lines examined, but also in the
"control" GE empty vector lines and in non-GE lines developed through tissue
culture. Somaclonal variation may therefore underpin many of the
compositional changes and may provide a mechanism by which "unintended"
changes in plant composition might occur independently of the process of
transformation and gene insertion itself. More extensive studies on the
impact of tissue culture on compositional variation are ongoing at the SCRI.

Given the range of phenotypes used in this study, it is perhaps surprising
that chemical composition is not affected more significantly. This indicates
that visible, morphological phenotype is not necessarily a good guide to
likely compositional changes. Similarly, compositional changes may not give
rise to an agronomic phenotype. This is why a holistic and case-by-case
analysis of specific GE lines is required to generate any opinion on
potential risk.

In our study the values for specific potato components that we analyzed (and
suggested by the OECD) fall well within published ranges for potato. It is
therefore unlikely that any of the changes observed would raise issues with
regard to food safety or nutritional value. However, several of these GE
lines would not be considered substantially equivalent to the parent due to
phenotypic perturbations.

References

1. OECD (1993) Safety evaluation of foods derived by modern biotechnology:
concept and principles.
(http://www.oecd.org/LongAbstract/0,2546,en_2649_34385_1946122_119666_1_1_1,
00.html)

2. EFSA [European Food Safety Authority] (2004) Guidance document of the GMO
Panel for the risk assessment of genetically modified plants and derived
food and feed.
(http://www.efsa.eu.int/science/gmo/gmo_guidance/660_en.html).

3. Kuiper HA and Kleter GA (2003) The scientific basis for risk assessment
and regulation of genetically modified foods. Trends Food Sci and Tech 14,
277-293

4. Howlett J et al. (2003) The safety assessment of novel foods and concepts
to determine their safety in use. Int J Food Sci Nutr 54 (Supplement),
S1-S32

5. OECD (2002) Consensus Document on Compositional Considerations for New
Varieties of Potatoes: Key Food and Feed Nutrients, Anti-Nutrients and
Toxicants.
[www.oecd.org]

6. Taylor MA et al. (2000) A potato alpha-glucosidase gene encodes a
glycoprotein-processing alpha-glucosidase II-like activity. Demonstration of
enzyme activity and effects of down-regulation in transgenic plants. Plant J
24, 305-316

7. Pedros AR et al. (1999) Manipulation of S-adenosylmethionine
decarboxylase activity in potato tubers. Planta 209, 153-160

8. Cellini F et al. (2004) Unintended effects and their detection in
genetically modified crops. Food Chem Toxicol 42, 1089-1125

[www.isb.vt.edu]

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