Working with fellow scientists at TSL, Brande Wulff from the JIC developed the new technology called ‘MutRenSeq’ which accurately pinpoints the location of disease resistance genes in large plant genomes and which has reduced the time it takes to clone these genes in wheat from five to 10 years down to just two.
Effective use of these resistance genes in wheat could increase global yields and vastly reduce the need for agro-chemical applications.
A resistance gene acts like a simple lock keeping the pathogen from infecting the plant. Over time, as many breeders and growers have found, pathogens can adapt to overcome an individual resistance gene and infect the plant. A stack of multiple genes acts like a multi-lever lock, making it much harder for new pathogens to evade the crop’s defenses.
“The challenge has always been finding enough resistance genes to create an effective multi-gene ‘stack’ against virulent pathogens like wheat stem rust and wheat yellow rust which, if left unchallenged, can decimate crops across the world. With the advent of this new technology, the development of a new variety of wheat with strong resistance to one or more of these pathogens is now within reach,” Wulff said.
Using this technology, scientists can very quickly locate resistance genes from crops, clone them and stack multiple resistance genes into one elite variety.
MutRenSeq is a three-step method for quickly isolating resistance genes based on:
- creating mutants from resistant wild-type wheat plants and identifying those with loss of disease resistance;
- sequencing genomes of both wild-type resistant plants and those which have lost resistance, and finally;
- comparing these genes in mutants and wild types to identify the exact mutations responsible for the loss of disease resistance.
Wulff collaborated with Evans Lagudah and Sam Periyannan at CSIRO Agriculture in Australia, who had used a chemical (EMS) to cause mutations in the genomes of a sample of resistant wild-type wheat plants.
“With MutRenSeq we can find the needle in the haystack: we can reduce the complexity of finding resistance genes by zeroing in from 124,000 genes, to just a single candidate gene,” Wulff said.
An alternative to pesticide-use is to build resistance into the crop by introducing resistant genes from other varieties of wheat into elite varieties.
“Finding and cloning these crucial genes has up until now been like looking for a needle in a haystack. The wheat genome is huge and contains many repeats,” Wulff said. “This new technology will transform this part of the scientific process. Though the next stage of stacking large numbers of genes correctly in the complex wheat genome is not easy and may take time, the advent of this new gene-detecting technology has brought the creation of one or more new elite varieties of wheat with long-awaited durable disease resistance much closer.”
