The backstory
Last year saw two research groups announce the first functional gene drive systems in plants. This technology dramatically increases the chances that particular genes and their traits will be inherited by the next generation. The chance of any individual gene being passed on is usually 50%, but these plant gene drives are reported to increase this to around 90% or more. Both groups developed similar gene drive systems in Arabidopsis thaliana, a small model pant, and reported proof of principle in laboratory settings (see Oberhofer et al., 2024 and Liu et al., 2024).
Such methods could allow genetic modifications to be forcibly spread through wild plant populations, even if such modifications are detrimental to the plants carrying them. For many years researchers have speculated that such technology could be applied to eliminate or suppress certain plant species, perhaps by disrupting their reproduction, and might be used to target agricultural weeds or invasive species. There have also been proposals to modify plant species, for example to make them more susceptible to herbicides. Such goals seemed a long way off because efforts to make the most common type of gene drives (so called ‘homing’ gene drives) work in plants have so far proved fruitless. However the recent results have brought these ambitions a step closer to becoming reality by using a different gene drive design (so called ‘toxin antidote’ gene drives).
Emerging biodiversity concerns
The annual horizon scanning exercise led by Professor William Sutherland at Cambridge University, UK, convened 32 international experts to identify emerging opportunities and threats for biodiversity conservation. Their 2024 survey identified fifteen ‘emerging issues’ including the development of gene drive technology in plants. The team highlighted that: ‘Potential risks include indefinite expansion of the gene drives, which may adversely affect target species…’. They also point to the possibility that gene drives could be transmitted to non-target species, and the need for strict regulatory control owing to the potential for ‘irreversible impacts’.
Our comments
While the horizon scan noted the possibility of using gene drives to somehow modify threatened plants to assist conservation efforts, we have only identified two such proposals in the scientific literature, both relating to trees (see Barett et al., 2019 and Cao et al., 2024).The fourteen other possible plant target species identified and listed in our Gene Drive Monitor database all relate to intentions to eliminate (or ‘suppress’) the target plant. Eleven of these species are agricultural weeds. Amongst these are species like Setaria glauca (wild millet), which, while they are considered weeds in some settings, have ecological roles in their own settings, such as being an important food source for wildlife (e.g. Steel et al 1982).
The 16 plant gene drive proposals catalogued in our database so far, indicate a potential trend of using the technology to control agricultural weeds. They also point to many questions about how this technology might develop in the longer term and its consequences.