The Hardy Wild Grass that could Save our Bread

An obscure species of wild grass contains "blockbuster" disease resistance that can be cross bred into wheat to give immunity against one of the deadliest crop pathogens.

A collaborative international team of researchers identified the stem rust resistance gene from the wild goat grass species Aegilops sharonensis.

The research team led by the John Innes Centre, The Sainsbury Laboratory, and the University of Minnesota used bioinformatic advances to develop the first accurate genome map of Aegilops sharonensis.

The genetic potential of this hardy relative of wheat found in Israel and southern Lebanon has been largely unexplored.

Using the genetic map and a search tool technique called Mutant Hunter the team scanned the genome for mutations looking for ones which were different in plants that were immune to stem rust, a disease which has troubled farmers for millennia.

This search identified a candidate gene, which the researchers thought was responsible for protecting plants. Using molecular tweezers, they isolated the gene of interest and transferred it into a susceptible plant, where it conferred strong protection against all tested strains of the wheat stem rust fungus, Puccinia graminis f. sp. tritici.

Dr. Brande Wulff, a wheat researcher at King Abdullah University of Science and Technology (KAUST), formerly a group leader at the John Innes Centre and one of the authors of the study said: "We now have this blockbuster gene that confers amazing immunity. If I were stem rust, I would be shaking in my spore."

"It has been an arduous research journey lasting many years, but we have now found this gene that confers broad-spectrum resistance. We have yet to come across an isolate of the pathogen which can overcome the gene," added John Innes Centre researcher Dr. Guotai Yu, first author of the study.

In this study which appears in Nature Communications, experiments showed that the Sr62 gene encodes a molecule called a tandem protein kinase. Ongoing studies are looking at how this gene functions so researchers can biologically engineer the mechanism to be more efficient.

The research team plans to employ the new gene as part of a stack of genes—bred into commonly used wheat varieties—using genetic modification technology. They predict more resistance genes will be identified in and cloned from populations of Aegilops sharonensis and other wild grasses using their methods of gene discovery and deployment.