For several decades we’ve been contributing to the global fight against rust, a devastating fungal disease. It is estimated that globally 5.47 million tonnes of wheat are lost to the stripe rust pathogen each year, equivalent to US$979 million.

The challenge

The ongoing battle against rust

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

Rusts are adaptable and evolve to overcome resistance. 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.

A few years later a new virulent strain of stripe rust appeared, this time in Australia, and has continued to cause serious annual crop losses ever since. It is a constant battle for wheat breeders to try to develop new cereal varieties with effective and long-lasting rust resistance.

[Wind and bird calls can be heard and the CSIRO logo and text appears: Rust, The Fungi that Destroy Plants]

[Image changes to show green wheat heads waving in the wind]

Narrator: Plants are under constant threat from invaders. 

[Camera zooms in on a single wheat stem]

This wheat crop stem is being attacked by a parasite. 

[Camera continues to zoom in on a rust spot on the side of the stem and then the image shows a red penetration tube growing from the rust spot]

The parasite is called rust, although it is actually a type of fungus.

[Music plays and the image shows the red penetration tube continuing to grow and then the image shows the wheat stem rotating in an clockwise direction]

[Image changes to show an animation of the inside of a wheat stem with a red penetration tube running between the cells]

The invading rust fungus has penetrated deep inside the plant tissue. 

[Music plays and the image shows the red penetration tube extending throughout the plant and then the camera pans to the left to show red spores pushing through the side of the plant]

As the invasion progresses the fungus produces spores.  These spores erupt from the surface of the plant.

[Music plays and then the camera zooms out to show the spores on the surface of the plant]

The spores spread creating pustules, new sites of infection. 

[Music plays and the image shows small red dots blowing from the plant and moving across the screen to the right and the image shows the plant with red fungal growth over the stem surface]

Soon the plant’s stem and leaves are covered in fungal growth. 

[Music plays and the image changes to show the fungal spores moving across the screen from the left to the right]

Carried by wind the fungal spores can travel great distances

[Image changes to show a fungal spore attaching to the surface of a wheat stem]

eventually reaching other potential hosts. 

[Music plays and the image shows the spore sending out a red penetration tube down the stem of the plant and entering through a small hole in the plant’s surface]

This spore must now find the nutrients it requires to grow.  Sending out the germ tube it seeks an entry point into the plant. 

[Music plays and the plant stem rotates in a clockwise direction and then the image shows the red penetration tubes moving inside the plant]

A newly formed penetration tube breaks inside the stem and the fungus extends further into the plant.

[Music plays and the camera zooms in on the red penetration tube moving inside of the plant and then the image shows hastorium penetrating through a cell wall inside the plant]

Once inside the stem, another structure called the haustorium is used to penetrate inside one of the plant’s cells. 

[Music plays and the image shows blue dots absorbing into the hastorium]

The fungus can now take nutrients from within the plant. 

[Music plays and the image shows red dots emanating from the hastorium and then the camera zooms in on the red dots and then shows green dots]

It also begins to secrete small protein molecules called effectors. 

[Music plays and the camera zooms in on the green and red dots]

This is a critical time for the plant.  If it can detect the fungal effector proteins it can try to stop the invasion. 

[Music plays and the camera zooms in to show a green dot binding to a red dot]

The plant has specialised resistance proteins which act like an immune system. 

[Music plays and the camera zooms out to show lots of green dots binding to red dots]

The resistance proteins can bind to the fungal effector proteins. 

[Music plays and the image changes to show the hastorium inside the plant cell]

This binding event alerts the plant that an infection is taking place. 

[Music plays and the image shows the cell wall containing the hastorium collapsing in]

Now that the parasite is detected the infected cells are sacrificed cutting off the energy supply to the invader. 

[Music plays and the image shows the red penetration tube shrivelling up]

The fungus will eventually starve and the plant can continue to grow. 

[Music plays and the image changes to show a plant stem with fungi attached to it and then two photographs appear of plants containing fungi]

New strains of fungi are constantly developing through evolution. 

[Image changes to show a plant leaf with fungi on it and a plant leaf without fungi and text appears: Vulnerable, resistant]

This can make some plants vulnerable to infection. 

[Music plays and the image changes to show rust on wheat stems]

Diseases like rust fungus have plagued crop production since people first began farming. 

[Image changes to show a header moving over a crop of wheat]

Globally, infections of rust destroy 15 million tonnes of wheat each year. 

[Image changes to show an aerial view of a seeder moving over a ploughed paddock]

Because of this wheat breeders must vigorously seek new sources of resistance to protect crops.

[Image changes to show spores and red penetration tubes through the cells of a plant and then the image moves to the right of the screen and the image changes to show wheat heads waving in the wind]

 Perhaps by investigating the interactions between plants and their invaders we could one day prevent the devastation caused by rust fungi.

[Music plays and CSIRO logo and text appears: Created by Chris Hammang, Producer Sean O’Donoghue, Scientific Consultant Peter Dodds, Music and Sound Design, Richard Tamplenizza, Brooke Trezise,@Broken Yellow]

[Text appears: Special Thanks, Jenny Vuong, Benedetta Frida Baldi, Julian Heinrich, Ludovic Autin, Software Blender, ePMV, Funding CSIRO, learn more at www.csiro.au]

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

Rust: the fungi that attacks plants

Our response

Attacking rust from all angles

We have been contributing to the global fight against rust for several decades. Our research has focused upon 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 may lead to new varieties of wheat that can 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. To date we have provided wheat breeders with more than 20 genetic markers, helping the industry keep one step ahead of this costly disease.

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The economic benefits of our rust research include higher yields for Australian grain growers and reduced costs through avoided fungicide application. A recent economic assessment estimates the net present value of CSIRO’s rust research to 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.

Recent published achievements have added to our arsenal in the global fight to protect our crops from rust, including:

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]

Protecting cereal crops against rust diseases

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