University of Connecticut researchers have refined a CRISPR-based, transgene-free genome-editing method that uses kanamycin selection to enrich edited cells after Agrobacterium delivery. The updated protocol is reported to be about 17 times more efficient for producing edited citrus plants and is applicable to other species. The approach could reduce regulatory and public resistance in some jurisdictions and help develop crops more resistant to disease, drought and heat.
Transgene-Free Gene Editing Boosts Crop Resilience — 17× Efficiency Reported in Citrus
Researchers at the University of Connecticut report a refined genome-editing method that leaves no foreign genes behind, offering a faster, simpler route to develop crops with improved resistance to disease and environmental stress. The work, published in Horticulture Research, was led by Yi Li, professor of horticulture and plant-breeding technology.
Many consumers and regulators object to genetically modified organisms (GMOs) because they can contain permanent foreign DNA. If genomic edits can be made without leaving transgenes, edited crops may fall outside some GMO regulatory definitions and face less public resistance — though classification varies by jurisdiction.
Beyond regulatory and consumer concerns, the technique addresses an urgent agricultural need: as climate change increases droughts, heat waves and disease pressure, crops that tolerate these stresses could help stabilize yields and farmer incomes and reduce food insecurity worldwide.
Technically, Li's team built on a transgene-free editing approach first described in 2018 and improved it by incorporating kanamycin selection during Agrobacterium-mediated transformation. Agrobacterium can transiently deliver CRISPR constructs into plant cells. Cells that temporarily express those constructs show greater resistance to kanamycin, allowing researchers to enrich for edited cells without integrating foreign DNA into the plant genome. According to the study, the updated protocol produced genome-edited citrus plants at a rate about 17 times higher than the original method and is adaptable to additional species.
"Our new but simple method is far more effective and can now be applied to a much wider range of plant species than our original approach," Li said in a university news release.
While promising, the method is not an automatic regulatory pass: legal classifications differ across countries, and edited varieties still require safety, performance and environmental assessments. Researchers also need to test traits in field conditions and continue monitoring for off-target edits. If those steps succeed, this approach could be a practical tool for developing disease-, drought- and heat-tolerant crops at scale.
Next steps: broader testing across crop species, field trials to validate trait performance, and dialogue with regulators and growers to clarify how transgene-free edits will be assessed and adopted.
