Innovative gene stacks enhance wheat rust resistance

14 January 2021

John Innes Centre researchers have helped in the development of pioneering gene stacking techniques to combat the growing threat of wheat rust.

Researchers at CSIRO, Australia’s national science agency, led the international effort to develop wheats with a stronger and potentially more durable level of resistance against rust diseases by “stacking” resistance genes together.

This represents a major advance over conventional wheat breeding protocols where individual resistance genes are added one by one.

The researchers developed novel genetic technologies that combine and insert five different wheat resistance genes. The bundling prevents separation in subsequent breeding generations of the plant, according to results published in Nature Biotechnology.

Lead CSIRO researcher Dr Mick Ayliffe said: “Our approach is like putting five locks on a door – you’re making it difficult to get in. Rigorous field testing showed that our gene stack approach provided complete protection against the rust pathogens we were targeting.”

Wheat provides around 20% of the world’s calorie intake, making crop protection vitally important for world food security, with cereal rusts also affecting barley, oats, rye, and triticale crops.

As rust is a global problem, it requires international collaboration with the team comprising researchers from CSIRO, University of Minnesota, Aarhus University, The John Innes Centre, USDA, Xinjiang University, and funding by the 2Blades Foundation.

Two of the resistance genes that made up the stack of five were cloned by scientists using a technique called MutRenSeq which rapidly detects resistance genes in wheat.

Dr Brande Wulff from the John Innes Centre, one of the researchers developing this technology said:

“It’s rewarding to see two of the genes that we helped clone have been used in this first stack in wheat. It is exciting because it demonstrates that the technology works; if there were to be a new epidemic of stem rust we would now have a potential solution. For those who are against the deployment of GM crops it becomes more difficult to oppose this when you have such an elegant solution that uses genes from wheat in a novel way to protect wheat.”

Future gene stacks are being developed for wheat using genome-editing tools to produce resistant crops that may be considered non-GM (genetically modified) in some countries, such as the USA.

Wheat stem rust is an historic disease in the UK and absent here for 60 years but, due to changing climate and a lack of resistance in modern wheat varieties it represents, an emerging threat.

Wheat rust can rapidly mutate, making it difficult for wheat breeders to respond quickly using conventional breeding. However, multiple genes compiled together in a gene stack can strengthen wheat’s defences and be deployed far more quickly.

Dr Ayliffe said this study had targeted stem rust, but the same technology can be used to breed against stripe and leaf rust diseases as well, and in different existing wheat varieties to add resistance.

He added: “We don’t know the limits of this new gene stacking technology yet. We currently have an even larger genetic stack with eight resistance genes, so even more protection against rust is possible.”

To learn more about the technologies developed by Dr Brande Wulff visit the John Innes Centre website.

Watch the video here!