Scientists employ genome editing techniques to develop disease-resistant rice

Researchers from the University of California, Davis, and an international team of scientists have used the genome-editing tool CRISPR-Cas to create disease-resistant rice plants, according to a new study published in the journal Nature. nature June 14th.

Small field trials in China showed that a newly created rice cultivar, developed through genome editing of a recently discovered gene, showed high yield and resistance to the fungus that causes a dangerous disease called rice blast. Rice is a staple crop that feeds half of the world’s population.

Guotian Li, co-lead author of the study, first discovered a mutant known as the lesion mutant while working as a postdoctoral researcher in Pamela Ronald’s lab at UC Davis. Ronald is co-lead author and Distinguished Professor in the Department of Plant Pathology and Genomics Center.

“It’s a big step forward that his team was able to improve this gene, making it useful for farmers. That makes it important,” Ronald said.

The roots of the discovery began in Ronald’s lab, where they created and sequenced 3,200 distinct rice strains, each with diverse mutations. Among these strains, the Guotian identified one with dark spots on its leaves.

“It was found that the strain was also resistant to bacterial infections, but it was very small and low-yielding,” Ronald said. “These types of ‘pest mimicking’ mutations have been found before but only in a few cases have they been beneficial to farmers because of the low yield.”

Working with CRISPR

Guotian continued research when he joined Huazhong Agricultural University in Wuhan, China.

He used CRISPR-Cas9 to isolate the gene associated with the mutation and used genome editing to recreate this resistance trait, finally identifying a line that had good yields and was resistant to three different pathogens, including the fungus that causes rice blast.

Ronald said that in small field trials planted in disease-heavy land, the new rice plants yielded five times more yield than rice, which had been damaged by the fungus.

“Blast is the most dangerous plant disease in the world because it affects virtually all rice-growing regions and also because rice is such a huge crop,” Ronald said.

future applications

The researchers hope to recreate this mutation in commonly grown rice varieties. For now, they have only improved this gene in a variety called Kitaake which is not widely grown. They also hope to target the same gene in wheat to produce disease-resistant wheat.

“A lot of these pest-mimicking mutations have been discovered and they’ve kind of been set aside because they’re so low-yielding. Hopefully, people can look at some of these mutations and see if they can modify them to get a good balance of resistance and high yield,” Ronald said.