Experiences and Prospects for Genetically Engineered Crops

Loren RiesebergExperiences and Prospects for Genetically Engineered CropsThe Royal Society of Canada is pleased to announce the publication of a new Expert Panel report from its sister academy, the National Academies in the United States. The full report can be accessed online.

Dr. Loren Rieseberg, FRS, FRSC has kindly provided a Canadian perspective on this report and its relevance to Canada and Canadians. Dr. Rieseberg is a Professor and Canada Research Chair in Plant Evolutionary Genomics at the University of British Columbia, Vancouver. His lab employs a combination of ecological and genomic approaches to study the origin and evolution of new species, exploit the genetic diversity of wild extremophile species for crop improvement, and combat invasive weeds, focusing on members of the sunflower family.

Experiences and Prospects for Genetically Engineered Crops – A Canadian Perspective

Genetic engineering refers to a suite of techniques that permit direct manipulation of an organism’s genetic make-up. These approaches are useful to agriculture because they offer a means for improving traits that cannot be introduced or modified effectively through conventional breeding. The key discoveries and technological advances that made genetic engineering possible coalesced during the 1970s, and the first genetically-engineered (GE) crop plant was produced in 1982. Commercial production of GE crops began a decade later. 

Despite enthusiasm for genetic engineering approaches among scientists and plant breeders, the impact of GE crops has been limited globally [1]. Currently, just 12% of the world’s cropland is devoted to GE crops, and GE varieties are available commercially for only nine food, three non-food, and two flower crops. Compared to global trends, GE crops are more widespread in North America, covering circa 42% and 31% of cropland in the USA and Canada, respectively. The USA also grows the largest diversity of GE crops, followed by Canada, where four GE crops are grown commercially: canola, maize, soybean, and sugar beet. Canadian production of all four crops is now dominated by a handful of GE cultivars.

The slow uptake of GE crops in agriculture stems largely from concerns about their effects on health and the environment, as well from expensive and time-consuming regulatory regimes that have been implemented in response to these concerns. According to Monsanto Canada, the cost of bringing a new GE trait into commercial production averages $136 million USD and takes 13 years [2]. As a consequence, no GE crops are grown in many countries, and the majority of GE crops and traits that have been developed are not in commercial production. Indeed, only two GE traits – insect resistance and herbicide tolerance – are in widespread use. However, it is not clear whether the many potentially adverse effects (and benefits) that have been ascribed to GE crops are warranted. 

A new report commissioned by the U.S. National Academy of Sciences [3], titled Genetically Engineered Crops: Experiences and Prospects, evaluates the strength of evidence supporting both negative and positive claims about GE crops. It also describes new technologies that not only increase the versatility of genetic engineering approaches, but also blur the boundaries with conventional breeding. Lastly, the report discusses how GE crops are regulated in different regions of the world and recommends a regulatory approach based on the characteristics of the trait and its potential for harmful effects, irrespective of whether genetic engineering was used or not. This is similar to the strategy already employed by Canada, but different from the approach taken by the USA and most other countries.  While Canada’s regulatory regime makes sense scientifically, national regulatory differences increase the cost of commercialization.

The report was written by a committee with expertise across a broad range of relevant disciplines, including agronomy, biochemistry, ecology, economics, entomology, food science, law, molecular biology, sociobiology, toxicology, and weed science. To ensure conclusions were credible and balanced, the committee first conducted a comprehensive survey of the primary literature, listened to presentations from 80 diverse experts, and received comments from 700 members of the general public. Consistent with this catholic approach to information gathering, the committee refrains from general statements about negative or positive effects of GE crops, but instead makes the important point that most such claims are context dependent, with their accuracy depending on the particular crop, trait, environment, scale of production, and government policy/regulation. However, the report does offer carefully worded findings that were supported by data, as well as recommendations regarding the kinds of experiments and analyses that are required to resolve uncertain effects. Below I summarize several of the report’s key findings and recommendations.

The committee found that GE maize, cotton, and soybean – the most widely grown GE crops – generally did provide positive economic benefits to the famers that grew them, although these were context dependent. Planting of GE insect-resistant crops was associated with reduced yield losses from insect pests, diminished use of chemical pesticides, and increases in non-target insect biodiversity. On the other hand, when resistance management strategies were not implemented, harmful levels of resistance evolved in insect pests. Similarly, production of GE herbicide-tolerant crops typically provided economic benefits to farmers and had little impact on plant biodiversity in farmers’ fields, but such crops were associated with the evolution of herbicide resistance in weeds. The report recommends more widespread implementation of resistance management strategies in the future.

The committee evaluated claims that GE crops are harmful to human and livestock health. No “substantiated” evidence was found of either short-term or long-term harm. The report does, however, suggest improvements in the design and analysis of animal-feeding studies.

The report also describes the emergence of new GE technologies, such as genome editing, that increase the power and precision of genetic engineering. Genome editing differs from conventional genetic engineering approaches in two main ways. First, genome editing allows changes to be made in a specific gene (or genomic region) of interest, whereas gene insertions with conventional genetic engineering methods are semi-random. Second, with genome editing, an organism’s genetic make-up can be altered without the introduction of foreign genetic material (or such material can be removed prior to commercialization). As a consequence, genome editing can be viewed as a kind of precision mutagenesis. Random mutagenesis is regulated as a conventional breeding tool, illustrating how the boundaries between crop improvement through conventional and genetic engineering approaches are increasingly blurred. The report recommends that regulatory regimes focus on trait novelty and potential harm, rather than on the process by which the trait was developed. As alluded to earlier, this recommendation would move regulatory policies closer to the “Plants with Novel Traits” strategy employed by Canada, potentially harmonizing North American regulatory regimes. The report further suggests that the application of new ‘omics‘ methods could increase the sensitivity and predictive power of such a regulatory approach. 

The report concludes with the following key points, which are equally relevant to Canada:

  • Genetic engineering and conventional breeding are complementary strategies, and the greatest gains in agricultural productivity and sustainability will come from employing both approaches rather than either one in isolation.
  • Increased funding in basic research will be required to understand and improve complex traits such as drought tolerance and nitrogen fixation, and introduction of some valuable traits is not possible without genetic engineering.
  • Investment in genetic engineering approaches should not come at the expense of other technologies that increase agricultural productivity and sustainability.

References

1.Where in the World are GM Crops? Canadian Biotechnology Action Network, Ottawa, Ontario, 2015. http://gmoinquiry.ca/wp-content/uploads/2015/03/where-in-the-world-gm-crops-foods.pdf

2.Isaacs J. 2015. Introducing plants with novel traits. AgAnnex, Simcoe, Ontario. http://www.agannex.com/plant-genetics/introducing-plants-with-novel-traits

3.Genetically Engineered Crops: Experiences and Prospects. National Research Council of the National Academies, The National Academies Press, Washington DC, DOI: 10.17226/23395, 2016. http://www.nap.edu/catalog/23395/genetically-engineered-crops-experiences-and-prospects