Improving detection of quarantine rust fungi

Pucciniales is the fungal order with the highest number of species on the EPPO A1/A2 and EU quarantine species lists. To enable adequate action in an outbreak situation or after introduction of a quarantine rust fungus, robust, sensitive and efficient diagnostic methods are required. With more than 8000 described species, rust fungi are the most species-rich monophyletic group within fungi, exclusively comprising plant parasites. This enormous diversity is currently distributed in more than 130 genera and 21 families. Currently there are 22 rust species in the EPPO A1 and A2 lists, belonging to six genera: Chrysomyxa, Cronartium, Gymnosporangium, Melampsora, Puccinia and Thekopsora. The number of rust species unwanted in the EU is significantly higher as all non-European species of the genera Gymnosporangium and Cronartium are defined as quarantine pests. With recent taxonomic changes and addition of many new species, especially from Asia, the number of rusts on these lists is expected to increase significantly in the future. Although ecologically and morphologically diverse, diagnostics of all rust fungi face similar challenges: they are very difficult or impossible to grow in axenic culture, they have large genomes and they have an intricate macro- and micro-morphology, with several spore stages that are not all present at the same time and can even occur on different host taxa. The main goal of this project is to pave the way to a more streamlined diagnostic process for quarantine rust fungi and facilitate the development of robust diagnostic methods.