Gene Editing Shows Promise for Improving Cacao

Cacao trees produce the cocoa beans that are the raw material of chocolate. Reliable productivity from cacao trees is essential to the multibillion-dollar chocolate industry and the livelihoods of millions of smallholder cacao farmers. Each year, diseases severely limit global production, with 20-30 percent of cocoa pods destroyed at preharvest.

According to Pennsylvania State University scientists, CRISPR-Cas9 could help breed cacao trees with enhanced resistance to diseases, and reported research results are the first to demonstrate the feasibility of using cutting-edge CRISPR technology to improve cacao.

Previous research on cacao identified the gene TcNPR3 that suppresses the plant's disease response. The researchers, led by Andrew Fister, postdoctoral scholar in plant science in Pennsylvania State University hypothesized that using CRISPR-Cas9 to knock out this gene would result in enhanced disease resistance. Using Agrobacterium tumefaciens, the researchers introduced CRISPR-Cas9 components into detached cacao leaves. Subsequent analysis of treated tissue found deletions in 27 percent of TcNPR3 copies.

When infected with Phytopthera tropicalis, a naturally occurring pathogen of cacao and other plants, the treated leaves showed greater resistance to the disease. The researchers also created CRISPR gene-edited cacao embryos, which they will grow into mature trees to test the effectiveness of this approach at a whole-plant level.

For more information, read the Penn State News.