Rice is a worldwide staple, feeding half the world’s population.
Golden rice, a genetically modified rice with high levels of beta-carotene, which converts to vitamin A, is highly valued in countries where vitamin rich food is limited.
To improve upon the conventional method of genetically modifying rice, scientists at the University of California, Davis, used CRISPR technology to more precisely transfer genes encoding certain desired traits into the rice genome.
CRISPR enables scientists to alter DNA sequences to modify gene function. It is used to create more disease-resistant and drought-tolerant crops.
The research team used Kitaake, a Japonica rice variety that received a large segment of donor DNA from Golden rice. The DNA was placed precisely into regions of the plant where researchers knew it would not cause adverse effects to the host rice.
Oliver Dong, a postdoctoral scholar in the UC Davis Department of Plant Pathology and Genome Center, said CRISPR has important advantages compared to conventional methods of genetic modification.
“Compared with conventional methods of gene delivery, the biggest advantage of using CRISPR to insert genes is that the insertion site is defined,” he said. “As well as inserting genes at a known position, CRISPR has also been used to disrupt genes (gene knockout) or modify the genetic code at a given gene. In application, CRISPR has been used to engineer rice with herbicide tolerance, or disease resistance to diverse pathogens.”
The research has opened up the possibility that genes controlling multiple desirable traits, such as providing high levels of beta carotene or producing a plant that is disease-resistant or drought-tolerant, can be clustered at a single position within the genome. This can lead to a significant reduction in the need for subsequent breeding endeavours.
Going forward, the research team will continue to refine the method of DNA transfer using the CRISPR technology.
“Now that we can insert large DNA fragments at a defined region in the rice genome, we would like to demonstrate the insertion of multiple trait genes at the same site by the iterative use of the method,” said Dong. “Stacking multiple genes at the same genomic position would simplify downstream breeding efforts.”
The research study was published recently in the journal Nature Communications.