Rice is a major staple food crop for over half of the global population. It
is known for having white grains, but some varieties exhibit pigmented
grains such as red rice. Red rice has high concentrations of healthful
proanthocyanidins and anthocyanins. Two complementary genes (Rc and Rd)
control the red coloration of rice grains. Wild rice species Oryza rufipogon
has red grains, while most cultivated varieties have white grains due to a
deletion in the Rc gene.

Scientists from Xiamen University and Fujian Academy of Agricultural
Sciences used CRISPR-Cas9 to restore the deleted portion of the Rc gene.
This successfully converted three elite white grain rice varieties into rice
plants with red grains, producing high levels of proanthocyanidins and
anthocyanidins. Furthermore, no significant change in major agronomic traits
was observed in the mutants compared to the wild type, implying that
restoring the Rc function had no effect on agronomic traits in rice.

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