Using CRISPR-Cas9, researchers from Texas A&M University were able to produce rice with an increased amount of resistant starch. The findings can help develop rice that is more beneficial for human health and possibly reduce the risk of diet-related chronic diseases.

Resistant starch is commonly found in cereal crops. It is not easily digestible nor absorbed by the small intestine, and is passed on to the large intestine which helps make the elimination of waste more efficient. Although rice is an excellent source of starch, it is mainly composed of amylopectin and amylose. The researchers saw this as an opportunity to develop rice rich in resistant starch using the rice cultivar Presidio, a semi-dwarf, high-yielding tropical japonica with high grain quality.

With previous knowledge that starch branching enzymes (SBEs) contribute to the increased levels of resistant starch in cereal crops, the researchers used multiplex CRISPR-Cas9 to simultaneously target four SBE genes in rice using the endogenous transfer RNA-processing system for expressing the single-guide RNAs targeting these genes. This resulted in the identification of knockout mutations at all four SBEs genes in rice plants. The next generation of rice plants exhibited different combinations of SBE genes, with several of them showing an increase of as much as 15% in resistant starch content. The study supports the potential of multiplex genome editing to develop high-resistant starch rice lines.

Read the full article in Plant Genome to learn more.