The End of the GMO? Genome Editing, Gene Drives and New Frontiers of Plant Technology

Date:02-01-2018

Author: Kathleen L. Hefferon and Ronald J. Herring, Cornell University

Abstract

Improvements to agriculture will constitute one of the world’s greatest challenges in the coming century. Political and social controversies, as well as complications of plant breeding, intellectual property, and regulation, have compromised the promised impact of ge‐ netically engineered – typically transgenic – crops designated as “GMOs.” Genome editing is a new suite of molecular tools for assisting biologists identify genes that control agronomic traits such as drought tolerance and pest resistance, as well as to elucidate how expression of these genes is intertwined within the functional framework of the cell. This technology has recently gained momentum for its ability to accelerate the crop breeding process in an un‐ precedented fashion and expand the range of crop varieties with improved precision and lower costs. This review explains the basic concepts and provides examples of how genome editing could help address the United Nation’s Sustainable Development Goals with respect to food, agriculture, and medicine. It concludes with a discussion of the potential social im‐ pact of genome editing and gene drive. These effects are contingent on the resolution of novel ethical and regulatory challenges that add new layers of complexity to societal questions of appropriate technology, in agriculture and beyond. We expect these questions to replace the irresolvable GMO debate.

Conclusions

Caribou Biosciences, a company founded by the University of Berkeley scientist and CRISPR pioneer Jennifer Doudna, is preparing to initiate field trials on varieties of corn and wheat edited for drought resistance (Montenegro 2016). Cibus, a San Diego based company, has used a novel form of genome editing to produce the first commercially available genome-edited crop SU Canola™, a herbicide resistant form of rapeseed that has received regulatory approval in Canada. Other agronomic traits under development by both of these companies include increased crop yield, disease tolerance, the production of healthier oils, and tolerance to high salinity.

Genome editing technologies hold the promise of crop and livestock improvement and even of curing patients of what have been up to now incurable diseases. The applications are vast and the human condition as a whole could be changed by genome editing. CRISPR-Cas9 as a genome editing platform, for example, has proved to be flexible across species, has high multiplexing potential, though as yet indeterminate intellectual property constraints. Since the technology leaves no sign of transgenesis, plants generated by genome editing are not considered to be GMOs and thus do not provoke the political and social energy that often accompanies biotechnology in agriculture. While inexpensive and relatively simple to implement, genome editing still has some drawbacks, including off-target effects and our inability to conclude what the long-term impact of this technology will be over many generations. Concerns regarding deliberate changes that genome editing can make to the course of human evolution seem for now to belong within the pages of a science fiction novel; however, so did many modern technologies at some point in history.

The immediate issue is that risk assessment guidelines to address environmental and human health effects lag far behind the rapid adoption of the technology in research labs around the world, outpacing bio-security frameworks for responsible regulation. More daunting still is that any workable mechanism for enforcing guidelines on a global scale is hard to conjure. One emergent agreement among practitioners is that genome editing be prohibited in germ lines, as results would otherwise be permanent over generations, altering evolution in unknowable ways. Yet how could such an agreement be enforced? Who would decide? One proposal has been to write restrictions into patents – the “ethical license” – as the Harvard group did in licensing to Monsanto (Guerrini et al. 2017). But then how do patents get enforced? Patent laws are national, and idiosyncratic, not global. Bio-property in transgenic seeds has proved virtually impossible to enforce internationally (Herring 2007).

While CRISPR-Cas9 technology becomes more effective and easier to use, research on other editing systems such as mega-nucleases are in the pipeline and will soon offer an even more diverse toolkit for scientists (Lambert et al. 2016). The term GMO – variously defined – is becoming ambiguous, more a normative and political construct than a biologically meaningful one. Genome editing as a whole thus challenges existing governmental regulatory structures designed to manage differences among organisms bred for new traits by different technologies (Esvelt 2016). It is not a reach to predict the end of the GMO as a cornerstone of regulating agricultural technology and flashpoint of conflict restricting progress. Genome editing offers a new frontier for plant technology that is unprecedented but brings along with it unprecedented challenges, particularly with the advent of gene drives. How these challenges are faced and dealt with will affect our world for generations to come.

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