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The challenge

The ongoing battle against rust

Rusts are a common fungal disease of plants, including many of Australia's cereal and horticultural crops.

Rust diseases occur in most wheat growing areas around the world, threatening global wheat yields. It is estimated that globally 5.47 million tonnes of wheat are lost to the stripe rust pathogen each year, equivalent to a loss of US$979 million.

As rust pathogens are adaptable and can evolve into new strains attacking previously resistant plants, we need to constantly develop new varieties to avoid major crop losses.

In 1999 a new virulent strain of stem rust was discovered in Uganda (so-called 'Ug99') which has spread to Iran and is encroaching on Asia. Ug99 is particularly devastating as it can overcome many of the resistance genes present in current wheat varieties, leaving many wheat crops vulnerable to infection.

It is a continual battle for wheat breeders to develop new cereal varieties with effective and long-lasting rust resistance.

Our response

Attacking rust from all angles

We have been contributing to the global fight against wheat rust for several decades. Our research has focused on the interaction between the rust pathogen and the crops it attacks. Using our expertise in wheat genetics we investigate both plants' defence mechanisms and rusts' ability to infect host plants.

The result is genetic markers that allow breeders to identify wheat varieties containing resistance genes which prevent rust infecting the plant or help the plants successfully battle a rust attack. These markers can be used to enable conventional breeding of rust resistant wheat.

One aim is to stack multiple resistance genes into a single wheat variety, significantly increasing its resistance and the length of time we expect it to remain resistant. Our research leads to new varieties of wheat that help farmers in Australia, and elsewhere, supply wheat and wheat products to people worldwide.

There are other ways to help control rust, such as fungicides and crop management. Avoiding susceptible wheat varieties and removing wheat between seasons stops the fungus building up in the crop. Issues surrounding long term sustainability and environmental impact of pesticides mean the use of resistance genes remains the most cost effective and environmentally friendly approach to control the fungus.

The results

Continually building the genetic arsenal

Australian crops have been protected for the past 60 years by the breeding of rust-resistant crop varieties that inhibit the development of rust diseases. By providing wheat breeders with genetic markers, we help the industry keep one step ahead of this costly disease.

The economic benefits of our research include higher yields for Australian grain growers and reduced costs through avoided fungicide application. The improved capacity of grain growers to prevent rust epidemics potentially contributes to greater stability in production and, at a national level, a higher level of food security.

A 2016 economic assessment estimates the net present value (NPV) of CSIRO's rust research for the wheat industry is approximately $382 million with $290 million attributable to CSIRO.

Rust is a major threat to global food security. We collaborate domestically and globally to achieve our goals.

Our cereal rust program is supported by domestic and international partners including the Grains Research and Development Corporation, Australian universities, Borlaug Global Rust Initiative, French National Institute for Agricultural Research (INRA), International Wheat and Maize Research Centre (CIMMYT, Mexico) and the Chinese Academy of Agricultural Sciences.

[Images move through of the different types of rust disease on wheat stems and leaves, an aerial view of a tractor ploughing and then Steve Jeffries talking to the camera and text appears: Steve Jeffries, GRDC]

Steve Jeffries: We have three major rust diseases in Australia, stem, stripe, leaf rust and we estimate that in the order of half a billion dollars of losses can occur if these rust diseases are not controlled.

[Image changes to show Dr Evans Lagudah talking to the camera and text appears: Dr Evans Lagudah, CSIRO]

Dr Evans Lagudah: So, there have been two basic types of rust resistance genes in wheat. There’s the seedling resistance genes and then there’s the adult plant resistance genes.

[Image changes to show a researcher looking at a pot of wheat seedlings and then the image changes to show Jeff Ellis looking at a flower and then the image changes to show rust on a wheat stalk]

To try and understand a bit more about the seedling resistance genes the CSIRO team led by Jeff Ellis used the flax model system that led to the identification of those genes.

[Image changes to show Dr Evans Lagudah talking to the camera]

So, using some really elegant genetics Jeff Ellis and his team were able to isolate the first rust resistance genes.

[Image changes to show an animation of a rust particle attaching to a wheat stem and then a rust coloured line shooting out from the rust particle and making its way into a hole in the wheat stem]

It turns out that they provided the molecular signatures to be able to understand or find most of the rust resistance genes that occur in the seedling group and using the modern tools that we have now in wheat genetics we’ve been able to identify the genes that are involved in these adult plant resistances.

[Animation image model rotations in an anticlockwise direction to show a 3-D view of the structure inside the wheat stem and then the image changes to show Dr Evans Lagudah talking to the camera]

An output of the research we’re doing is to be able to provide molecular tags for each of the resistance genes and this I call the molecular markers and we’ve been able to do that for about 20 different resistance genes.

[Images move through of wheat grains in petri dishes, hands picking up wheat grains with tweezers, researchers looking through microscopes and then Dr Evans Lagudah talking to the camera]

The impact of having these molecular tags is that because breeders are constantly breeding for a wide range of characters, trying to improve yield and grain quality, since 1988 we’ve had continuous support what was then the Wheat Research Council which later on became the Grains Research and Development Corporation.

[Image changes to show a photo of the CSIRO team and then the image changes to show Dr Evans Lagudah drawing up liquid into a syringe and then putting it into a small plastic receptacle]

Steve Jeffries: The CSIRO team have been global leaders in the identification of the genetic control of rust resistance genes which in turn have led to the development of tools that plant breeders can use to effectively and accurately select for resistance genes in a cost effective, accurate way that doesn’t require the generation of an epidemic.

[Image changes to show Dr Evans Lagudah and a female looking at heads of wheat and then the image changes to show Dr Evans Lagudah talking to the camera]

Dr Evans Lagudah: And as a result of this we are now in the position to be able to provide rust resistance genotypes and markers, not only for the Australian market but also for the international market.

[Image changes to show a harvester moving through a crop]

It’s important that we not only protect the wheat that we have in Australia but to be able to also help protect what goes outside of Australia.

[Music plays and CSIRO logo and text appears: Australia’s innovation catalyst]

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