Genetic Engineering and Plant Disruption

Be prepared to be surprised: Genetic engineering (GE) often causes less disruption to plant functioning than older breeding techniques.

This fact never fails to surprise people.  I suppose that is because most assume that GE is so far-fetched and unnatural that it must be terribly damaging to plants.  The reality is that the targeted DNA manipulations of GE are no more disruptive—and are commonly less disruptive—to a plant’s genes, its gene expression, its suite of proteins, and its chemical composition than more traditional methods of crop improvement.  Scientific support for this statement can be found in the following scholarly reports  [1-8].  This list of citations is actually incomplete since there are papers not listed that could be.

Hybridization between species is a common plant breeding practice.  Nevertheless, the title of this research paper gives me pause: “Hybridization as an Invasion of the Genome [9].”  Dr. Barbara McClintock, one of the most respected biologists of the 20th century, considered hybridization between species to be a cause of “genome shock.”  And this classic breeding technique generates no public protest.  Should it?  Should we be concerned about breeding techniques that cause “genome shock?”

One way I have learned to help people understand this phenomenon is through the following video:

 

These videos are not perfect metaphors for genetic processes, but there are adequate for communicating the fundamental fact that genetic changes due to GE are more targeted than those achieved by older techniques (which, by the way, are still very important for crop improvement).

If unanticipated health consequences from GE manipulations merit concern, what about the unanticipated health consequences of each new conventionally bred crop variety [10]?  One might say, “But breeding by human selection has been used for thousands of years old, so it must be safe, right?”  Yes, human selection of plants is an ancient practice, but every plant is an unprecedented genetic and epigenetic creation, unique onto itself. Without testing, no one knows whether a new non-GMO crop variety is safe.  Every new plant presents unknown risks due to its unique genetic and epigenetic heritage.

My understanding is that Canada requires safety evaluations of all new crop varieties, not simply those derived from GE.  From a scientific standpoint, it makes more sense to me to regulate new varieties based on the qualities the variety possesses, rather than how its genetic changes were made.  It is something for us in the USA to consider, particularly since GE commonly causes less disruption to the plant than conventional breeding.

Citations

  1. Ricroch, A. E., Assessment of GE food safety using ‘-omics’ techniques and long-term animal feeding studies. N Biotechnol, 2013, Vol. 30, p. 349-54, DOI: 10.1016/j.nbt.2012.12.001. Available from: http://www.ncbi.nlm.nih.gov/pubmed/23253614
  2. Schnell, J., Steele, M., Bean, J., Neuspiel, M., Girard, C., Dormann, N., Pearson, C., Savoie, A., Bourbonniere, L. and Macdonald, P., A comparative analysis of insertional effects in genetically engineered plants: considerations for pre-market assessments. Transgenic Res, 2015, Vol. 24, p. 1-17, DOI: 10.1007/s11248-014-9843-7. Available from: http://www.ncbi.nlm.nih.gov/pubmed/25344849
  3. Gao, L., Cao, Y., Xia, Z., Jiang, G., Liu, G., Zhang, W. and Zhai, W., Do transgenesis and marker-assisted backcross breeding produce substantially equivalent plants? A comparative study of transgenic and backcross rice carrying bacterial blight resistant gene Xa21. BMC Genomics, 2013, Vol. 14, p. 738, DOI: 10.1186/1471-2164-14-738. Available from: http://www.ncbi.nlm.nih.gov/pubmed/24165682
  4. Batista, R., Saibo, N., Lourenco, T. and Oliveira, M. M., Microarray analyses reveal that plant mutagenesis may induce more transcriptomic changes than transgene insertion. Proc Natl Acad Sci U S A, 2008, Vol. 105, p. 3640-5, DOI: 10.1073/pnas.0707881105. Available from: http://www.ncbi.nlm.nih.gov/pubmed/18303117
  5. Lehesranta, S. J., Davies, H. V., Shepherd, L. V., Nunan, N., McNicol, J. W., Auriola, S., Koistinen, K. M., Suomalainen, S., Kokko, H. I. and Karenlampi, S. O., Comparison of tuber proteomes of potato varieties, landraces, and genetically modified lines. Plant Physiol, 2005, Vol. 138, p. 1690-9, DOI: 10.1104/pp.105.060152. Available from: http://www.ncbi.nlm.nih.gov/pubmed/15951487
  6. Ladics, G. S., Bartholomaeus, A., Bregitzer, P., Doerrer, N. G., Gray, A., Holzhauser, T., Jordan, M., Keese, P., Kok, E., Macdonald, P., Parrott, W., Privalle, L., Raybould, A., Rhee, S. Y., Rice, E., Romeis, J., Vaughn, J., Wal, J. M. and Glenn, K., Genetic basis and detection of unintended effects in genetically modified crop plants. Transgenic Res, 2015, Vol. 24, p. 587-603, DOI: 10.1007/s11248-015-9867-7. Available from: http://www.ncbi.nlm.nih.gov/pubmed/25716164
  7. El Ouakfaoui, S. and Miki, B., The stability of the Arabidopsis transcriptome in transgenic plants expressing the marker genes nptII and uidA. Plant J, 2005, Vol. 41, p. 791-800, DOI: 10.1111/j.1365-313X.2005.02350.x. Available from: http://www.ncbi.nlm.nih.gov/pubmed/15743445
  8. Herman, R. A. and Price, W. D., Unintended compositional changes in genetically modified (GM) crops: 20 years of research. J Agric Food Chem, 2013, Vol. 61, p. 11695-701, DOI: 10.1021/jf400135r. Available from: http://www.ncbi.nlm.nih.gov/pubmed/23414177
  9. Mallet, J., Hybridization as an invasion of the genome. Trends Ecol Evol, 2005, Vol. 20, p. 229-37, DOI: 10.1016/j.tree.2005.02.010. Available from: http://www.ncbi.nlm.nih.gov/pubmed/16701374
  10. Kok, E. J., Keijer, J., Kleter, G. A. and Kuiper, H. A., Comparative safety assessment of plant-derived foods. Regul Toxicol Pharmacol, 2008, Vol. 50, p. 98-113, DOI: 10.1016/j.yrtph.2007.09.007. Available from: http://www.ncbi.nlm.nih.gov/pubmed/17983697
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