Stem rust in oats.
PHOTO: Robert Park
Oat is attacked by two rust diseases: crown rust and stem rust. The pathogens that cause these diseases do not infect other cereal crops. Crown rust attacks the leaves and leaf sheaths, is orange in appearance and has been a major problem in grazing oats, particularly in northern regions of the eastern Australian cereal belt.
As its name suggests, stem rust infects mainly stems, but can also infect other plant parts. It is darker in colour and has tended to be more of a problem in milling oats. Oat growers in Victoria and South Australia may recall a severe stem rust in cultivar Euro in 2001, which caused significant yield and quality reductions.
In early 2013, the appearance of a new pathotype (strain) of crown rust on oat from north-eastern Australia was reported, which could attack the previously resistant cultivar Drover. This left Aladdin as the only oat cultivar with resistance to this disease. Unfortunately, in late 2014, yet another pathotype of crown rust was found that can infect Aladdin, meaning that there are now no grazing oat cultivars with good levels of resistance to crown rust. Options for controlling this disease in grazing oat in north-eastern Australia are now very limited.
The situation with stem rust resistance in oat is not much better, with pathotypes present in Australia that can overcome resistance of all cultivars.
New research being funded by the GRDC is fast-tracking the identification and incorporation of minor gene or adult plant resistance to crown rust in Australian oat germplasm. Intensive efforts are also underway to find new sources of resistance to stem rust that can be used in the development of new cultivars.
Australian oat breeders are not alone in dealing with the challenges of rust. An Oat Rust Forum was held at the University of Minnesota in the US in February this year and brought together oat breeders, rust pathologists and industry stakeholders from North America and Australia. The meeting sought to develop a strategy for a community-wide approach to manage oat rust resistance and to set clear direction for funding agencies on how this effort should be supported.
A strong commitment was given by all present to work together closely to optimise outputs from research and to advocate for more research support.
It was also clear that newly available technologies will enable better understanding of oat rust pathogens and, importantly, the development of new tools to add to the breeder’s tool box. The latter includes genomics tools such as a high-quality genome sequence for oat, gene discovery and annotation tools, coupled with transformation systems to speed up oat improvement.
Professor Robert Park
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