A British research group has reduced the time it takes for crop breeders to breed disease resistance genes into their stock from over a decade to several months.
Modern crops have been bred to be larger and grow faster. The drawback is that these crops have very little genetic diversity and are therefore very vulnerable when a disease or pest epidemic hits. For this reason, there’s a big need for technology that can quickly equip them with genes that could help them resist the disease.
In a study published in Nature Biotechnology, researchers at the John Innes Centre collected wild, genetically diverse strains of wheat and screened which ones were resistant to the destructive fungal disease stem rust. The researchers then sequenced the plants’ DNA, identifying four key genes common to plants resisting the disease.
Instead of looking at the entire wheat genome, which is huge and takes a long time, the researchers searched specifically for the immune genes of the plants, which are the most likely to be involved in disease resistance.
“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,” stated Brande Wulff, lead researcher in the project at the John Innes Centre. “This used to be a process that took 10 or 15 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.“
This new technique, called speed cloning, circumvents the need to spend years isolating disease resistance genes from wild strains by cross-breeding them. According to Wulff, breeding and crossing wild plants is also difficult. “Their traits include seeds that fall off the plant at the mere touch, an unruly growth habit, and seeds that are very difficult to peel, akin to putting bamboo splinters below your nails.”
“With the new technique, we don’t need to make crosses in the lab. We use the natural variation and recombination that has arisen in nature over hundreds of thousands of years.”
Once the genes are identified and cloned, they can either be inserted into domestic breeds using genetic engineering, such as using the gene editing tool CRISPR-Cas9, or selectively bred into the population by crossing the breeds. By growing wheat shoots under special LED lights, the lab is able to selectively breed the genes into plants twice as fast as in the field, taking around eight weeks per generation.
The group has no immediate plans to commercialize the technique, but is currently collaborating with undisclosed industrial partners to improve their breeding techniques.
For making better crops, selective breeding sped up by speed cloning could be a viable alternative to genetically engineered organisms, especially given the restrictions placed on gene editing in the EU. However, with selective breeding, it’s harder to control which genes are transferred, so it can be less efficient than genetic engineering.
In the field of agricultural biotech, there is big potential for improving crops using genetic tools. Last year, for example, the giant German company BASF obtained a license to genetically engineer crops with disease resistance genes using a form of CRISPR-Cas9 called CRISPR-Cpf1.
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