Barley stripe rust defence

Industry guards against introduction of serious overseas barley pathogen

Diseases
The form of Stripe rust that causes the most damage in barley crops, known as BYR. PHOTO University of Sydney

The form of Stripe rust that causes the most damage in barley crops, known as BYR. PHOTO University of Sydney

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BYR pathogen represents a significant threat to Australian industry if introduced.

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Barley Stripe rust is a significant problem in some parts of the world. But, fortunately, this is not the case in Australia because the pathogen that causes the most damage in barley crops - known as 'BYR' - does not occur in this country.

If introduced to Australia however, the BYR pathogen is expected to cause yield losses comparable with the wheat Stripe rust pathogen - known as 'WYR' - since these two pathogens have similar biology.

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A Stripe rust form similar to BYR was identified in eastern Australia as part of national rust surveys by the Australian Cereal Control Program at the University of Sydney's Plant Breeding Institute (PBI) in 1998.

Isolated off barley grass, this Stripe rust pathogen is known locally as 'BGYR'. It can infect some Australian barley cultivars, notably Skiff, Tantangara and Maritime (PBR) varieties, but the level of infection is generally low and yield losses have not been recorded.

National cereal rust monitoring at PBI has shown that the BGYR pathogen is still present in eastern Australia's cereal growing regions, but we have not found evidence that it has acquired any increased ability to infect barley cultivars.

To ensure that all barley cultivars grown in Australia are resistant to BGYR, breeding germplasm is screened routinely in the greenhouse and in the field at PBI for responses to the pathogen.

Australian barley varieties susceptible

Although BYR does not occur in Australia, offshore testing of Australian barleys with Mexican BYR isolates over the past 20 years has shown that many are susceptible. Consequently, this pathogen represents a significant exotic disease threat to the Australian barley industry.

GRDC-funded research has allowed for ongoing BYR testing of Australian barley germplasm in Mexico, which was extended to Ecuador in 2017.

This work has identified many barleys with resistance to BYR at sites in Mexico and Ecuador, which has allowed us to begin undertaking its genetic characterisation.

To date, we have identified single resistances in the Australian barley cultivars Yerong (located on barley chromosome 5HL) and Franklin (7H), and three resistances in the European barley cultivar Pompadour (1H, 5H, 7H).

The ultimate aim of this research is to identify Stripe rust resistance that would be of greatest value to the Australian barley industry and to develop new tools for use by Australian barley breeding programs to incorporate resistance to BYR to help protect against a future incursion.

GRDC Research Codes 9175448, 9175952, 9176057

More information: Robert Park, 02 9351 8806, robert.park@sydney.edu.au

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