Genome editing used to create disease resistant rice

Researchers used the genome-editing tool CRISPR-Cas to create disease resistant rice plants, according to a new study published in the journal Nature.

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

A co-lead author of the study initially discovered a mutant known as a lesion mimic mutant. 

The roots of the discovery began in one of the co-corresponding authors lab, where they created and sequenced 3,200 distinct rice strains, each possessing diverse mutations. Among these strains, the second co-corresponding author identified one with dark patches on its leaves. 

“He found that the strain was also resistant to bacterial infection, but it was extremely small and low yielding,” the first corresponding author said. “These types of ‘lesion mimic’ mutants have been found before but only in a few cases have they been useful to farmers because of the low yield.”

The second co-corresponding author used CRISPR-Cas9 to isolate the gene related to the mutation and used genome editing to recreate that resistance trait, eventually identifying a line that had good yield and was resistant to three different pathogens, including the fungus that causes rice blast. 

In small-scale field trials planted in disease-heavy plots, the new rice plants produced five times more yield than the control rice, which was damaged by the fungus, the first corresponding author said.

“Blast is the most serious disease of plants in the world because it affects virtually all growing regions of rice and also because rice is a huge crop,” the author said. 

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

“A lot of these lesion mimic mutants have been discovered and sort of put aside because they have low yield. We’re hoping that people can go look at some of these and see if they can edit them to get a nice balance between resistance and high yield,” the author said.