Weeds, often a nuisance for gardeners, present a formidable challenge in agricultural settings where they can rapidly develop resistance to herbicides. Among these is Amaranthus palmeri, known as Palmer’s pigweed, which has demonstrated robust resistance across various crops like corn and soybeans. Addressing such challenges requires genetic modification capable of reversing these resistances.
At the forefront of this genetic battle are gene drives, mechanisms designed to spread specific genetic traits throughout populations, even if those traits offer no benefit to the host organisms. These drives serve two main purposes: population modification and suppression. They can render disease-carrying mosquitoes unable to transmit malaria or enhance crop resilience in anticipation of climate shifts. Conversely, gene drives can target local elimination of invasive species like weeds. However, stringent controls are imperative to confine genetic modifications to intended species and prevent unintended consequences.
Recently developed by researchers at Caltech, a pioneering gene drive technology named ClvR (pronounced “cleaver”) promises tailored solutions for plant species. This innovation mitigates accidental gene editing during cross-pollination scenarios, ensuring precise genetic alterations. Crucially, ClvR can be programmed to self-limit its spread to a defined number of generations, thereby curtailing its temporal and spatial impact. This breakthrough marks the first engineered gene drive system for plants, specifically targeting modifications at the level of plant sex cells.
Published in Nature Plants on June 17, the study outlines how ClvR utilizes CRISPR/Cas9 technology to influence plant gametes, ensuring inheritance of desired genes. The system employs a “toxin/antidote” approach: Cas9 acts as the “toxin,” selectively eliminating gametes lacking the desired genetic trait, while the “antidote” ensures survival of gametes containing the target gene of interest. This dual mechanism effectively promotes the spread of desired genetic modifications within plant populations.
Lead author Georg Oberhofer, formerly a postdoctoral scholar at Caltech and now a research scientist, emphasizes the versatility of the ClvR system. By customizing toxin and antidote genes, researchers can tailor interventions to specific plant species, preempting unintended genetic transfers. Moreover, the system facilitates diverse applications, from enhancing crop traits to combating invasive species or bolstering the resilience of endangered plants against environmental stressors.
Bruce Hay, professor of biology and biological engineering at Caltech, underscores the transformative potential of ClvR: “The system offers a species-specific tool for addressing global challenges such as food security and ecological resilience. We look forward to collaborating with stakeholders to apply these innovations.”
Funding for the research was provided by the Caltech Center for Evolutionary Science, the Resnick Sustainability Institute, the National Institutes of Health, and the US Department of Agriculture. Collaborators on the study include Caltech researchers Michelle L. Johnson, Tobin Ivy (PhD ’24), and Igor Antoshechkin, director of the Caltech Genomics Facility.
The publication, titled “Cleave and Rescue gamete killers create conditions for gene drive in plants,” signifies a pivotal advancement in genetic engineering, offering promising avenues for sustainable agricultural practices and ecological management.
