Use of the powerful gene-editing tool CRISPR-Cas9 could help to breed cacao trees that exhibit desirable traits such as enhanced resistance to diseases, according to plant scientists. The cacao tree, which grows in tropical regions, produces the cocoa beans that are the raw material of chocolate. Reliable productivity from cacao plants is essential to the multibillion-dollar chocolate industry, the economies of producing countries and the livelihoods of millions of smallholder cacao farmers. But each year, several plant diseases severely limit global production, with 20-30 percent of cocoa pods destroyed preharvest. CRISPR stands for clustered regularly interspaced short palindromic repeats. It is a way to modify an organism's genome by precisely delivering a DNA-cutting enzyme, Cas9, to a targeted region of DNA. The resulting change can delete or replace specific DNA pieces, thereby promoting or disabling certain traits. Previous work in cacao identified a gene, known as TcNPR3, that suppresses the plant's disease response. The researchers hypothesized that using CRISPR-Cas9 to knock out this gene would result in enhanced disease resistance. The ultimate goals of the cacao research are to help raise the standard of living for smallholder growers and stabilize a threatened cocoa supply by developing plants that can withstand diseases, climate change and other challenges.
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