One mantra that is repeated by anti-GMO advocates is that genetic engineering – the process of introducing foreign genes into a plant genome – has the potential to dramatically alter gene expression in the transgenic plant, and thus may lead to unanticipated and harmful changes in the plant. The response from the scientist is that traditional breeding is logically expected to lead to much larger genome-wide changes, and that we actually will have less control over these. With the advent of genome-wide transcription assays, it is now possible to test this directly (as opposed to trying to reason through the matter. An example of such a study is that recently published by Baudo et al. The bottom line of this study – gene expression is much less affected by the insertion of a transgene than by the process of traditional crop breeding. The abstract of the study is after the fold. As always, enjoy.
Detailed global gene expression profiles have been obtained for a series of transgenic and conventionally bred wheat lines expressing additional genes encoding HMW (high molecular weight) subunits of glutenin, a group of endosperm-specific seed storage proteins known to determine dough strength and therefore bread-making quality. Differences in endosperm and leaf transcriptome profiles between untransformed and derived transgenic lines were consistently extremely small, when analysing plants containing either transgenes only, or also marker genes. Differences observed in gene expression in the endosperm between conventionally bred material were much larger in comparison to differences between transgenic and untransformed lines exhibiting the same complements of gluten subunits. These results suggest that the presence of the transgenes did not significantly alter gene expression and that, at this level of investigation, transgenic plants could be considered substantially equivalent to untransformed parental lines.
Maria Marcela Baudo, Rebecca Lyons, Stephen Powers, Gabriela M. Pastori, Keith J. Edwards, Michael J. Holdsworth, Peter R. Shewry (2006). Transgenesis has less impact on the transcriptome of wheat grain than conventional breeding Plant Biotechnology Journal, 4 (4), 369-380 DOI: 10.1111/j.1467-7652.2006.00193.x