New study challenges current risk assessment methods
 

EXCERPT: [Says Christoph Then for Testbiotech,] “The paradigm applied in the current risk assessment of genetically plants has to be reviewed. We suggest that all further authorisations for genetically engineered plants producing insecticidal toxins are suspended.”
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New publication shows unexpected reactions in genetically engineered maize MON810 when exposed to environmental stress

Testbiotech, 10 April 2015
http://www.testbiotech.org/en/node/1200

* Gene expression and content of insecticidal toxins cannot be reliably predicted

10 April 2015 / Scientists from Switzerland and Norway have now published the results of an investigation into genetically engineered maize MON810, which produces an insecticidal protein, a so-called Bt toxin (Trtikova et al., 2015). In the investigation, two varieties of maize MON810 were grown in climate chambers and subjected to defined stress conditions i.e. cold/wet and hot/dry. According to the authors, this is the first study to report on whether there is a relationship between transgene expression and protein production in Bt maize under changing environmental conditions.

The results are surprising: In general, the Bt content was on average higher in one variety compared to the other. Under cold/wet conditions the content of Bt increased in one of the varieties, but not in the other. The activity of the DNA construct inserted into the plants was lowered significantly under hot/dry conditions in one variety, but this had no influence on the Bt content.

“These results show that the stress reactions of maize containing the DNA for the MON810 event are not predictable in reliable way. These findings are highly relevant for the risk assessment of MON810 or 1507 maize and other genetically engineered plants expressing single or several Bt proteins”, says Christoph Then for Testbiotech. “The paradigm applied in the current risk assessment of genetically plants has to be reviewed. We suggest that all further authorisations for genetically engineered plants producing insecticidal toxins are suspended.”

Currently, European Food Safety Authority (EFSA) risk assessment does not include any in-depth investigation of interactions between the transgenic plant genome and the environment. There are, for example, hardly any data at all on how genetically engineered plants could react to ongoing climate change. Reliable data on the Bt content are needed to assess potential toxicity in non-target organisms. For example, risks for non-target organisms such as soil organisms or the larvae of protected butterflies can be much higher than assumed if the Bt content shows a high range of variation. It should also be taken into account that immune reactions due to the consumption of food and feed derived from transgenic plants have been observed in several feeding studies. It is likely that these effects are dose-dependent and therefore the content of the Bt toxins also plays a decisive role in the risk assessment for food and feed.

This pilot project was realised with the support of Testbiotech and with funding from the Manfred Hermsen Umweltstiftung.

A Testbiotech Backgrounder: http://www.testbiotech.org/en/node/1199
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Transgene Expression and Bt Protein Content in Transgenic Bt Maize (MON810) under Optimal and Stressful Environmental Conditions
Miluse Trtikova, Odd Gunnar Wikmark, Niklaus Zemp, Alex Widmer, Angelika Hilbeck
PLOS One, April 8, 2015
DOI: 10.1371/journal.pone.0123011
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0123011 (open access)

Abstract

Bt protein content in transgenic insect resistant (Bt) maize may vary between tissues within plants and between plants growing under different environmental conditions. However, it is unknown whether and how Bt protein content correlates with transgene expression, and whether this relationship is influenced by stressful environmental conditions. Two Bt maize varieties containing the same transgene cassette (MON 810) were grown under optimal and stressful conditions. Before and during stress exposure, the upper leaves were analysed for transgene expression using quantitative RT-PCR and for Bt content using ELISA. Under optimal conditions there was no significant difference in the transgene expression between the two investigated Bt maize varieties whereas Bt protein content differed significantly. Transgene expression was correlated with Bt protein content in only one of the varieties. Under stressful environmental conditions we found similar transgene expressions as under optimal conditions but Bt content responded differently. These results suggest that Bt content is not only controlled by the transgene expression but is also dependent on the genetic background of the maize variety. Under stressful conditions the concentration of Bt protein is even more difficult to predict.