Genome editing is used to make rice disease resistant

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

Small-scale field trials in China showed that a newly created rice variety, developed through editing the genome of a newly discovered gene, exhibits high yields and resistance to a fungus that causes a serious disease called rice blast. Rice is an important crop that feeds half of the world’s population.

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

“It’s a pretty good step forward that his team can enhance this gene, making it potentially useful for farmers. That makes it important,” said Ronald.

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

“He found that the strain was also resistant to bacterial infection, but it was very small and the yield was low,” said Ronald. “This type of ‘mutant lesion mimic’ has been found before but only in a few cases have they been useful to farmers because of their low yields.”

Work with CRISPR

Guotian continued his 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 that resistance trait, ultimately identifying a strain that had good yields and was resistant to three different pathogens, including the fungus that causes rice blast.

In small-scale field trials planted in disease-ridden plots, the new rice plants yielded five times more yield than control rice, which was damaged by the fungus, said Ronald.

“Blast is the most serious crop disease in the world because it affects almost all rice growing areas and also because rice is a very large crop,” said Ronald.

future application

The researchers hope to recreate this mutation in commonly grown rice varieties. Currently they only optimize this gene in a model variety called “Kitaake” which is not widely grown. They also hope to target the same gene in wheat to create disease-resistant wheat.

“Many of these lesion-mimicking mutants have been discovered and ruled out due to their low yield. We hope that people can take a look at some of these and see if they can edit them to get a good balance between resistance and high yields,” said Ronald.

Rashmi Jain with the UC Davis Department of Plant Pathology and Genome Center also contributed to the research, as did scientists from BGI-Shenzhen, Huazhong Agricultural University, Jiangxi Academy of Agricultural Sciences, Northwest A&F University and Shandong Academy of Agricultural Sciences, China; Lawrence Berkeley National Laboratory and UC Berkeley; University of Adelaide, Australia; and the University of Bordeaux, France.

Research in Ronald’s lab is supported by the National Science Foundation, the National Institutes of Health, and the Joint Bioenergy Institute which is funded by the US Department of Energy.