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Gene Drives: A Fork in the Road for the GMO Debate

Gene Drives: A Fork in the Road for the GMO Debate

By Charles Robin

What are the moral and ethical concerns about gene drives, and how should the technology be regulated?

At the end of last year, a United Nations bio­diversity meeting rejected calls for a moratorium on gene drives. In the months before that meeting, a letter signed by eminent and well-respected biologists including Jane Goodall and David Suzuki asserted that the use of gene drives in natural populations “is a moral and ethical threshold that must not be crossed without great constraint”.

This raises two very important issues. What are the moral and ethical issues? And in what way should the technology be regulated?

Synthetic gene drives can be thought of as a derivative of conventional genetically modified organisms (GMOs), for which many of the moral and ethical issues have already been widely debated and the technology highly regulated in many countries. So let us focus on the differences between gene drives and GMOs, and ask where the moral and ethical threshold actually lies.

Unlike the early releases of transgenic plants, gene drive technology is not currently being championed by private companies with a profit motive. In fact, it is not immediately obvious how gene drives can be monetised given that they are self-spreading.

One possibility is that gene drives could be coupled to agrichemicals. For example, a gene drive could spread a gene that makes a pest sensitive to a particular patented chemical that is sold by that company. Another possibility is that companies follow the lead of British biotechnology company Oxitec, which has developed sterile insects using transgenic technologies and manages release strategies for various tiers of government so that disease vectors are controlled.

Generally, however, it seems unlikely that a “gene drive” debate will follow the same course as the GMO debate, which was entangled with the profit motives of companies like Monsanto. Likewise with concerns about the intellectual property rights covering synthetic gene drives, at the moment these seem to be out of corporate control and held in the relatively safe hands of academics in the United States.

The most fundamental differences between gene drives and standard GMOs is that gene drives affect free-living and free-breeding natural populations and are designed to spread. This is not the case with transgenic cotton or herbicide-resistant canola, where there is an imperative not to spread the transgenes to GM-free cultivars in a neighbour’s paddock or to any weeds with the potential to hybridise with the crop plant. In the case of these GM crops there have been substantial efforts to prevent such movement (such as making the GM crops sterile) and to monitor related crops to detect any possible gene flow that may have occur. However, organic farmers need not be concerned about gene drives, in this respect, because it’s likely that gene drives will target pests rather than the crops themselves.

So should the threshold be set so that no gene drives are allowed because genetic engineering of a natural population is a step too far? Will, then, alternatives such as the broad application of relatively indiscriminate insecticides remain our default strategy?

Perhaps the threshold should discriminate between particular types of drives. Maybe gene drives that simply knock out gene function are tolerable whereas those that deliver cargo genes are not. Or perhaps those aimed at conferring a new attribute to the population are acceptable, whereas those that aim to reduce the number of individuals in a population size are not?

Some have talked about deliberately eliminating pest species, like mosquitoes, using a variant of gene drives sometimes referred to as “crash drives”. Is reducing species bio­diversity in such a way a step too far?

If we accept that some gene drives are acceptable, then what are the hazards of tinkering with the genetic constitution of natural populations? One major concern is that gene drives could drastically affect ecosystems, and because ecosystems are complex the consequences may be hard to predict and the outcomes unexpected and devastating.

Perhaps we should limit gene drives to organisms that have recently invaded Australia. For instance, the tomato and potato psyllid (Bactericera cockerelli) recently entered Western Australia and has been the target of interstate quarantine restrictions. Drosophila suzukii, a small fruitfly, a major pest of soft-skinned fruits like berries, has caused significant damage in the United States and Europe, where it has recently invaded. Incursions of Drosophila suzukii into Australia are expected soon. Both of these insect species reproduce sexually, so they could be the targets of gene drive technology. Surely elimination from Australia of pest incursions using a “crash drive” will protect ecosystems rather than damage them?

But that introduces a new issue. How do we stop gene drives spreading to places where they are not intended? Would a gene drive designed to protect Australian agriculture spread overseas? Pest organisms do not carry passports or recognise national boundaries, and a pest in one country may be a key part of a fragile ecosystem in another.

As a completely hypothetical example, if New Zealanders developed a gene drive to reduce pest populations of the brushtail possum, how would we make sure that the gene drive would not spread to Australia? It would only take the movement of one fertile animal by some irresponsible person.

Several engineering solutions to this problem have been suggested. For example, more sophisticated gene drives have been conceived that either reverse previous gene drives or separate the gene drive components so that they only combine in an active form in a period immediately after release.

There are also features that could be incorporated into the design of experimental genes drives so that would they would only work in certain contexts. For instance, nutritional supplements available only in lab environments could act as an “on switch” so that any individuals that escaped from the research environment would not have any impact on natural populations.

Clearly the other solution is regulation. There are hierarchies to the public policy concerning gene drives. Gene drives could have international ramifications, with international bodies such the United Nations already tracking and debating developments in the technology. In Australia, gene drives currently fall under the purview of the Gene Technology Act 2000, and various relevant authorities have an interest depending on the context in which gene drives are applied.

Universities and other research institutions need to encompass gene drives into their institutional research responsibilities, and there is also a responsibility placed on individual scientists to develop the technology appropriately. Some leading researchers in the field are already advocating pre-registration of gene drive experiments so that experimental plans can be easily accessed by whoever is interested and concerns raised before the experiments have even been conducted.

Important contributors to the public discussion on gene drives are the various national academies of science. For instance, the Australian Academy of Science recently launched a discussion paper entitled Synthetic Gene Drives in Australia: Implications of Emerging Technologies (https://goo.gl/SRTKX7).

The development of gene drives represents a significant advance in the ability of humans to manipulate biology and the environment. They define a new type of population. Until now we might classify organisms into:

  • domesticated populations such as the crops, farm animals and pets that have been crucial characteristics of our civilisations;
  • captive populations that we keep in zoos and parks;
  • natural populations that are free-living and free-breeding that have survived from the evolutionary past; and
  • feral populations, such as feral cats and brumbies, that have a genetic history of domestication yet are now wild and free-breeding.

If gene drive populations come to be, we would have free-living and free-breeding populations that have had their genetic composition deliberately manipulated by humans.

Gene drives represent a fork in the road. We might call the road the Anthropocene Highway. The fork has multiple prongs, or options, and we should start to consider which one we should be steering toward.


Dr Charles Robin is a Senior Lecturer at the School of BioSciences at the University of Melbourne.