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Sydney Opera House provided the backdrop for the 6th Borlaug Global Rust Initiative Technical Workshop. The Borlaug Global Rust Initiative (BGRI) was established in 2005 to address the threat of a new race of wheat stem rust (caused by Puccinia graminis f. sp. graminis) called Ug99. The BGRI brought together rust researchers from around the world to tackle this problem and in 2008 the Durable Rust Resistance in Wheat (DRRW) project was launched, which provided a formal funding stream. The technical workshops initially aimed to report on developments within the DRRW project but later meetings in the series were broadened to cover the other cereals rusts.
This was my first BGRI workshop and formed a part of a wider visit to Australia supported by BSPP to further my research in wheat yellow rust (caused by Puccinia striiformis f. sp. tritici) and wheat brown rust (caused by Puccinia triticina). Prior to the workshop I was also able to visit the rust group at the Plant Breeding Institute, University of Sydney, to exchange results, ideas and methodologies. An additional side meeting on surveillance also brought together a subgroup of approximately 80 people who had interests in or run the virulence surveys around the world.
This BGRI Technical Workshop was the final formal meeting of the DRRW project, which is due to finish in January 2016. As such, most of the presentations focused on summarising achievements of the project and discussions on future directions. In the opening talk, Bob McIntosh (PBI, University of Sydney) summarised what 10 years of research in the durable rust resistance in wheat project had achieved and highlighted that the results achieved prompted further questions rather than being a completely closed case. Robert Park (PBI, University of Sydney) gave a thought provoking talk on durable resistance.
Since Roy Johnson’s definition of durable resistance there have been many attempts to classify resistance genes into the category of being either durable or non-durable, with NBS-LRR genes being classed as the former, and a range of different gene classes being categorised as the latter. Robert’s presentation sought to challenge some of these assumptions, for example the major gene Lr24. This gene gives an immune response to most races of wheat brown rust and was effective in Australia for 17 years and would therefore fit the criteria for durable resistance.
Robert went on to suggest that this durability was due to the presence of an additional resistance gene, the adult plant resistance gene Lr34. This combination could suggest that not all major genes are bad news, particularly if deployed in combination with other partial resistance genes.
For me, the most interesting session focused on the surveillance of the rust diseases across the world. The BGRI initially focused on not only tracking the new race of stem rust but also developing capability worldwide to monitor the pathogen at a regional and national level. Several training courses have been run and facilities built. Dave Hodson (CIMMYT) showcased the advances made in the surveillance of stem rust across the world, focusing primarily on East Africa and South Asia. From the initial 10 sites the surveillance programme had received over 21,000 samples from 35 countries. New resources were developed to manage this data with the use of tablets in the field streamlining the process and the wheat rust toolbox website being developed to host the results; www.rusttracker.cimmyt.org. The outcome of this extensive surveillance network is that since the initial discovery of the race Ug99 in 1998, a further two races were detected within this group in 2005, and in 2015 there have been 11 races detected within the Ug99 group in 13 countries. The investment made in the surveillance programme was highlighted by the occurrence of a new race of stem rust in 2013. A swift epidemic caused by the new “Digelu” race (named after the variety it was first found on) gave the group cause for concern when it emerged that this race was very different to the Ug99 group of isolates. It was later determined to be an incursion from the Middle East and although it had been reported in previous years, the danger to East Africa was underestimated. With the use of the now established surveillance programme, the new race was quickly identified and germplasm screening could be adapted accordingly to reduce the lag time between finding a new race and deploying resistant wheat varieties.
The data from the surveillance work were also used in epidemiological models presented by Marcel Meyer (University of Cambridge). These models aim to predict the movement of spores following an initial sighting of a new race based on meteorological data and spore movement data. The ultimate aim for this work would be to develop decision making tools for use in the affected and neighbouring locations.
As a relative newcomer to the rust research community I would like to thank the BSPP for helping me to attend this meeting. As well as being able to attend the interesting scientific presentations, this visit has enabled me to develop new and existing links with other virulence surveys with a view to future collaborations.
Sarah Holdgate NIAB