Cacao trees – which provide the key ingredient in chocolate – are prone to diseases, with around 30% of the global production being destroyed each year.
But scientists believe they may have found a solution: gene editing. The process involves using a tool known as CRISPR-Cas9 to delete a gene that makes the trees vulnerable by suppressing their disease response.
The technology has already been used in humans, with scientists successfully altering DNA in defective embryos. Researchers from Penn State University in the US used CRISPR-Cas9 to remove a gene called TcNPR3 from some of the leaves of the Theobroma cacao tree.
The team then infected the cacao leaves with a naturally occurring plant pathogen called Phytopthera tropicalis. According to the researchers, the treated leaves showed greater resistance to the disease.
The scientists say that mutation of “only a small amount of the copies of the targeted gene” could be enough to make trees resistant to the pathogen.
Study author Mark Guiltinan, professor of plant molecular biology at the university, said: “Our lab has developed several tools for the improvement of cacao, and CRISPR is just one more tool.
“But compared to conventional breeding and other techniques, CRISPR speeds up the process and is much more precise. “It’s amazingly efficient in targeting the DNA you want, and so far, we haven’t detected any off-target effects.”
So far, the scientists have demonstrated the technique by looking at one gene but say there may be “thousands of genes involved in disease resistance”, with Penn State postdoctoral scholar and study leader Andrew Fister adding: “We want to evaluate as many as we can.”
Siela Maximova, a senior scientist and professor of horticulture at Penn State, believes the ultimate goal is to help the cocoa farmers by stabilising supply, which involves developing plants that can withstand diseases as well as climate change and other challenges.
She added: “This study provides a ‘proof of concept’ that CRISPR-Cas9 technology can be a valuable tool in the effort to achieve these goals.” The research is published in the journal Frontiers in Plant Science.