According to a study published in Nature on June 14, researchers from the University of California Davis and an international team of scientists have used the genome-editing tool CRISPR-Cas to develop disease-resistant rice plants.
The newly developed rice variety, formed through genome editing of a recently discovered gene, showed high yields and resistance to the fungus that causes a serious disease known as rice blast, as reported by small-scale field trials in China. Most of the world’s population is fed by a significant crop known as rice.
Co-author and postdoctoral scholar Guotian Li found a mutant known as a lesion mimic mutant while working 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 quite a step forward that his team was able to improve this gene, making it potentially useful for farmers. That makes it important,” Ronald stated.
The research that led to the discovery was conducted at Ronald’s lab, which produced and sequenced 3,200 distinct rice strains with various mutations. Guotian recognized one of these strains 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,” Ronald stated. “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.”
Guotian’s research continued after he enrolled at Huazhong Agricultural University in Wuhan, China. He isolated the gene linked with the mutation using CRISPR-Cas9 and then used genome editing to recreate the resistance trait. He eventually discovered a strain with a high yield and resistance to three different pathogens, including the fungus that causes rice blast.
According to Ronald, in small-scale field trials planted in disease-prone areas, the new rice plants produced five times greater yield than the disease-damaged control rice. Ronald stated, “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.”
In widely farmed rice varieties, the researchers intend to recreate this mutation. This gene has only been developed in a model variety named “Kitaake”, which is not widely cultivated. They also plan to target the same gene in wheat to produce 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,” Ronald stated.