This year marks the centenary of cereal rust research at the University of Sydney. The work was initiated by Professor Walter Waterhouse, who was appointed as a lecturer in plant pathology, genetics and plant breeding by the university in 1921.
Before joining the University of Sydney, Professor Waterhouse served with the First Australian Imperial Force in World War I. He was awarded the Military Cross for conspicuous gallantry at Pozieres in July 1916. After the war, he spent time at Imperial College London and at the University of Minnesota in St Paul, where he saw firsthand the wheat rust research being undertaken by two scientists, professors Stakman and Levine.
After accepting the position at the University of Sydney in 1921, Professor Waterhouse initiated research on wheat and barley rust diseases. In the early 1930s he initiated research on oat rust diseases.
The first rust sample Professor Waterhouse received for pathotype (race) analysis was collected from Hawkesbury Agriculture College in May 1921; it was a sample of Stem rust that he identified as race “43” – which we now know would have been virulent on the Stem rust resistance genes Sr5 and Sr21. This was one of six pathotypes of the wheat stem rust pathogen that he found. He used these to artificially infect wheat lines to find those that were resistant and could be used in resistance breeding.
Dominant rust pathotype
Interestingly, these original six races were overrun by a new pathotype of presumed exotic origin that Professor Waterhouse detected in 1925. This new pathotype, “126”, became dominant across Australia from 1929, after which the old pathotypes were no longer detected. Race 126 has not been detected since 1969, but a viable isolate of it is still maintained and used in rust research at the University of Sydney.
Cereal rust pathogenicity surveys at the university over the past 100 years have documented a further 13 invasions of exotic wheat rust isolates, two barley rust isolates, and a probable three oat rust isolates, the last being a new pathotype of the wheat stripe rust pathogen detected in 2017 that we now know originated from Europe.
Newly arrived rust pathotypes often act as ‘founders’, from which new pathotypes are derived via simple mutation. An example of this was reported in the previous GroundCover™ issue (Issue 147) , once again for wheat Stripe rust gaining increased virulence, especially on some durum wheats.
While we continue to develop and use DNA-based diagnostics to characterise rust samples from crops, the only way to identify rust pathotypes is virulence testing in greenhouse tests using differentials carrying different resistance genes. DNA-based tests using the latest cutting-edge tools would have failed to detect all of the important virulence changes in Australian cereal rust populations in recent times.
The staff and students of the University of Sydney’s Plant Breeding Institute are proud to continue Professor Waterhouse’s foundational work on cereal rust pathogens in Australia. We are indeed fortunate to have benefited from the legacy of his work; the Plant Breeding Institute was established by a donation from the Flour Mill Owners Association of NSW, made to the University of Sydney in recognition of the early work done on developing rust-resistant wheats.
This early work has also had tremendous international impact; the landmark rust resistant high-yielding wheat cultivar Gabo was grown in the US and Canada, and used by Dr Norman Borlaug in Mexico as a source of daylength insensitivity. Gabo and its sib-line Timstein appear in the pedigrees of many early Mexican wheats that came from Dr Borlaug’s program, including Cajeme, Mayo and Nainari.
The success of the surveys started by Professor Waterhouse back in 1921 depends entirely on the samples received for analysis. Growers and other stakeholders are encouraged to monitor crops closely for rust and to forward freshly collected samples in paper only to the Australian Cereal Rust Survey, at University of Sydney, Australian Rust Survey, Reply Paid 88076, Narellan, NSW, 2567.