Dr Colin Wellings, University of Sydney, Plant Breeding Institute (PBI), Cobbitty (seconded from Industry & Investment NSW) says plant pathologists in the United States have identified for the first time a sexual stage in the stripe rust life cycle.

“This is a very important development in our understanding of the biology of this pathogen, and unlocks a mystery that has remained unanswered for more than a century,” he said.

The Grains Research and Development Corporation (GRDC) invests significantly in stripe rust research via PBI.

The wheat stripe rust pathogen has a 30-year history in Australia, and over this time the pathogen has adapted through a series of newly emerging pathotypes.

Each new pathotype is closely related to a previous pathotype, indicating that the stripe rust pathogen behaves as a clone in its reproduction.

Several of the new pathotypes have adapted to certain wheat and triticale varieties, and in some instances have caused significant economic losses for Australian grain growers.

“Rust diseases of cereals and grasses may have a complete life cycle, including up to five spore stages, or variations with fewer spore stages,” Dr Wellings said.

“The significance of the sexual stage lies not only in pathogen survival but importantly in the potential for recombination of virulence and the emergence of pathotypes with greater capacity to cause crop damage.

“However, the sexual host is not present in Australia and so does not represent a threat to our cropping industries.”

He said the discovery opened the door to new opportunities in understanding the genetic nature of the pathogen.

With the onset of the winter crop season, growers are urged to be alert for any signs of rust in cereal crops.

Plant samples with suspected rust infections can be mailed in paper envelopes (do not use plastic wrapping or plastic lined packages): Australian Cereal Rust Survey, Plant Breeding Institute, Private Bag 4011, Narellan NSW 2567.

* Visit www.grdc.com.au/rustlinks