Articles

The second most common trait of genetically modified (GM) plant is insect resistance. This is usually obtained by introducing, into the plant’s genome, genes from the bacterium Bacillus thuringiensis (Bt), which produce insecticidal proteins. A new study has compared the quality of a GM insect-resistant maize (MON810) and its appropriate non-GM near-isoline counterpart as feed for Daphnia magna (a water flea) and found significant differences.

D. magna fed with the Bt maize leaves displayed a significantly smaller body size as well as reduced fecundity later in the life cycle, indicating increased stress levels, compared to those fed non-Bt leaves. They reproduced approximately 20% less offspring.

This is the first study to examine GM-plant leaf material in the D. magna model and provides evidence of negative fitness effects of a GM maize hybrid on a non-target model organism under chronic, high dietary exposure. The scientists postulate that the transgenic proteins exert a non-target effect in D. magna and/or unintended changes were produced in the maize genome by the transformation process, producing a nutritional difference between GM-maize and non-GM near-isoline.

The scientists call for further studies over the full life cycle of model organisms, considering that important biological effects may only be detected after chronic exposure. Furthermore, they highlight the importance of conducting safety testing for GM plants with plant material and plant-produced recombinant proteins, rather than with microbially produced recombinant proteins.