FEB 04, 2019 4:53 PM PST

A Rapid New Method to Help Modern Crops Resist Disease

WRITTEN BY: Carmen Leitch

Scientists that want to make crops more resistant to disease, without impacting yield or using pesticides, have developed a technique for finding and cloning wild genes that will confer resistance. Researchers can now search a library of candidate genes from wild versions of domesticated crops to identify genetic sequences that help plants stand up to pests and disease. This new technique has been called AgRenSeq. 

“Having speed cloning in our toolkit means that elite crops can be made more resilient which means higher yields and reduced reliance on pesticides to protect crops,” explained Dr. Brande Wulff, a project leader at the John Innes Centre. "We have found a way to scan the genome of a wild relative of a crop plant and pick out the resistance genes we need - and we can do it in record time. This used to be a process that took ten or fifteen years and was like searching for a needle in a haystack. Now we can clone these genes in a matter of months and for thousands of pounds instead of millions."

Researchers from John Innes Centre and colleagues in the US and Australia reported the AgRenSeq tool in Nature Biotechnology. Their work showed that four resistance genes could be identified in a wild relative of wheat, and then cloned and introduced into wheat. These genes can protect the crop from a serious pathogen called stem rust and would have taken many years with conventional tools. With AgRenSeq, it was done in only months. 

To test their method, the team utilized a panel of 151 strains of a wild grass. They exposed the plants to the pathogen that causes stem rust and looked for the plants that were resistant or susceptible. They correlated that data with genomic information from the plants and found the genes that conferred resistance.

Modern crops have lost a lot of their genetic diversity; they have been specialized to maximize yield, for example, and are susceptible to disease. Adding wild genes back to those genomes could be a good way to make crops more resilient. Naturally crossbreeding the plants would add in too many undesirable traits, and could take a long time. This method aims to streamline the process.

John Innes Centre researcher Dr. Sanu Arora with domesticated wheat one of its wild relatives. / Credit: Andrew Davis

"What we have now is a library of disease resistance genes, and we have developed an algorithm that enables researchers to quickly scan that library and find functional resistance genes," explained the first author of this work Dr. Sanu Arora.

“This is the culmination of a dream, the result of many year's work. Our results demonstrate that AgRenSeq is a robust protocol for rapidly discovering resistance genes from a genetically diverse panel of a wild crop relative,” Wulff said. “If we have an epidemic tomorrow we can go to our library and inoculate that pathogen across our diversity panel and pick out the resistance genes. Using speed cloning and speed breeding we could deliver resistance genes into elite varieties within a couple of years, like a phoenix rising from the ashes.”

Sources: AAAS/Eurekalert! via John Innes Centre, Nature Reviews GeneticsNature Biotechnology

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