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RustWatch: A European early-warning system for wheat rust diseases

Periodic Reporting for period 2 - RUSTWATCH (RustWatch: A European early-warning system for wheat rust diseases)

Reporting period: 2019-11-01 to 2021-04-30

RustWatch is a stakeholder driven H2020 initiative developing a European early-warning system for rust diseases, which is a major challenge for plant health in Europe. Plant health is a key component for achieving the goals of the EU ‘farm-to-fork’ strategy of reducing 50% of pesticide use and a goal of 25 % of total farmland used for organic farming by 2030. The project is funded by the European Union’s Horizon 2020 research and innovation program (grant agreement 773311), engaging 12 universities/research institutes, 5 agricultural advisory services, and 7 SMEs/industries in Europe. RustWatch is based on intensified collaboration between beneficiaries within plant pathology, plant breeding, agronomy, agro-chemistry, molecular genetics and Information and Communication Technologies (ICT).
A core activity is to provide a better understanding of pathogen biology by faster and more efficient diagnostic methods to detect new rust races and genotypes, which enables us to investigate pathogen population changes, including potential exotic incursions of rust strains into Europe, and to study the role of pathogen aggressiveness, temperature adaptation, and Berberis spp. as sexual host as driver of evolution. This has been possible by strengthening the collaboration among European rust diagnostic laboratories, e.g. new procedures for alignment of experimental procedures and interpretation of results, and exchange and compilation of genotypic and phenotypic data using the facilities provided by the WheatRustToolbox
RustWatch has allowed us to perform rust surveys in 14 European countries without national rust diagnostic labs, and rust sampling was intensified and diversified by utilizing existing stakeholder networks within plant breeding, variety testing (VCU) and agricultural advisory services. For instance, new races of yellow rust, which caused shifts in rust susceptibility for currently grown wheat varieties, were first detected in samples collected by stakeholder (VCU) partners. Genotypic and phenotypic data are stored according to the FAIR principles on a web-based database platform, termed the Wheat Rust Toolbox, and visualized on publically accessible web-sites, e.g. but country representatives and data providers have access to a number of more detailed analytic tools for their “own” data. Because the Wheat Rust Toolbox serves the global wheat and rust community, we are able to analyse rust populations in Europe in a global context. RustWatch has developed a new data management systems to accommodate rust surveillance data from Europe, as well as three mobile Apps, including a crowdsource App, which are targeted towards different areas of wheat rust early warning and user groups.
A survey of the alternate host for yellow and stem rust (Berberis spp.) in 2018-2020 showed that rust fungi are often present on common barberry in Europe. Cereal-infecting stem rust was recovered from Berberis spp. in areas in Germany, UK, Spain and Switzerland. Although yellow rust was not observed on the alternate host growing wild in Europe, we showed that two indigenous species of barberry in Spain were indeed susceptible to yellow rust under experimental conditions (rust quarantine lab) in Denmark. Stem rust expanded to new cereal-growing areas in Southern Europe, France, Ireland and Norway. In northern Spain, stem rust on cereals in close proximity to Berberis spp. revealed high pathogen diversity, including high diversity for virulence including Sr31-virulence, which is characteristic for Ug99, however, our genotyping showed that these samples were not related to the Ug99 lineage.
We provided new knowledge about rust resistance specificities in European wheat germplasm to all three wheat rust fungi, e.g. by integrating epidemiological assays (in vivo) and SNP genotyping for a large number of rust resistance genes. One-hundred-and-thirteen SNP markers for rust R-genes were identified; originally planned for providing knowledge about rust resistance genes in a set of approximately 1300 European wheat varieties/lines, which form the basis for better exploitation of resistance resources in plant breeding. This material represents 95% of the cultivated wheat area of 17 European countries over 20 years, which will allow us to survey more than 60 rust R-genes, and provide extended information about the use of rust R-genes in European wheat production at the landscape level.
The integration with existing stakeholder networks increased the expertise and efficiency in rust monitoring within plant breeding, agrochemical industry, agricultural advisory services, and Value for Cultivation and Use in cereals. This allowed us to investigate more than 200 European elite wheat varieties and breeding lines towards novel races of yellow rust, brown rust and black (stem) rust in field trials in six European countries. More than 50% of the material had a high level of resistance to yellow rust, generally a lower level of resistance to leaf rust, and insufficient resistance to black (stem) rust, a disease that was only present at epidemic levels in southern Europe. Results from multi-location field trials in Pakistan have confirmed a high level of resistance towards yellow rust in European wheat material, even when exposed to highly diverse pathogen populations in the near-Himalayan region
The activities and results in PR2 have already had significant impact for several stakeholder groups, i.e. translating information about rust pathogen changes and regional differences in Europe into the impact on host susceptibility of a huge number of breeding lines and cultivated wheat varieties. This is essential for optimizing the ongoing plant breeding for disease resistance in the plant breeding industry and for providing valuable prevention and control recommendations by regional and national agricultural advisory services for the benefit of end-user farmers. The integration with the pre-existing Value-for-Cultivation-and-Use (VCU) network allowed us to detect new pathogen races, and the VCU testing got inew knowledge about rust populations improving the interpretation of VCU results.
The case study approach has allowed us to investigate the threats of invasive rust races at the regional scale and suggest IPM-based prevention and control options adjusted to the relevant agronomical practices and environmental conditions in the considered region. For instance, after the extensive 2019-yellow rust epidemics in Denmark (one of the case study regions) farmers responded by dramatic changes in varietal distribution. Due to the emergence of a new yellow rust race, more than 60% of the wheat area was deployed by highly susceptible varieties in 2019. This figure has dropped below 10% in the current growing season, where yellow rust ‘resistant’ varieties are deployed on 80% of the winter wheat area.
Overall, the concept of ‘shared facilities’, the development of standardized disease assessment scales and procedures, the development of new Apps for disease surveillance, and our web-based and database-driven information and communication strategy has effectively contributed to connect the different stakeholder groups and networks beyond our expectations from the beginning.
RustWatch -open field day