CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) has become a leading technology in genetic research, offering precise, targeted approaches to modifying DNA. While its applications began in human therapeutics, CRISPR is now steering fresh new advancements in agriculture, particularly in combating Huanglongbing (HLB), also known as citrus greening, a disease that continues to devastate the global citrus industry.
Since 2013, scientists at the University of Florida Institute of Food and Agricultural Sciences have explored CRISPR’s promise in editing plant cells. According to Dr. Nian Wang, a researcher at the university, CRISPR acts like a “molecular scissor.” For HLB, it removes sections of DNA in citrus plants that make them susceptible to the disease, thereby enhancing their resistance or tolerance to infection.
After years of comprehensive study, Wang’s team has identified about 40 potential genetic targets thought to influence citrus immune responses and oxidative stress when under attack by the HLB-causing bacterium Candidatus Liberibacter asiaticus (CLas).
One standout aspect of Wang’s research is its focus on creating transgene-free genome-edited citrus. Unlike traditional genetically modified organisms (GMOs), which incorporate DNA from different species, transgene-free editing avoids introducing foreign genetic material.
This approach reduces regulatory hurdles and addresses public concerns over GMOs, paving the way for more accepted and faster adoption by growers. Indeed, says Wang, this new approach is “simpler and easier.” Specifically, he noted that “Non-transgenic genome edited lines are relatively easy to go through the regulatory approval process.”
The adoption of CRISPR in citrus is a significant leap forward, but is not without its challenges. HLB differs from diseases like citrus canker, where specific genetic targets, such as the LOB1 gene, are well-understood. HLB requires a broader approach due to its ability to trigger harmful immune responses and oxidative stress within citrus plants. This complexity means the research team must test numerous genetic targets.
Additionally, the timeline for creating disease-resistant citrus trees is extensive. From identifying targets to fully functional field trials, the process can take 8–10 years. This includes rigorous evaluations to make sure the plants have strong resistance to HLB while maintaining desirable fruit quality and yield.
CRISPR technology is opening doors to a brighter future for the citrus industry. Moving forward, Wang says new research will focus on efficiently integrating disease-resistance genes into citrus plants without adding non-citrus sequences. Another key milestone will likely be testing transgene-free citrus varieties that are tolerant or resistant to HLB in field environments.
Although the road ahead is long, CRISPR offers immense promise in helping the citrus industry recover from one of its greatest challenges to date. With continued research and collaboration, genetically edited citrus could soon become a standard tool in the fight against HLB, helping to rejuvenate the battered global citrus markets.