Abstract
Tilletia controversa causing dwarf bunt of wheat is a quarantine pathogen in several countries. Therefore, its specific detection is of great phytosanitary importance. Genomic regions routinely used for phylogenetic inferences lack suitable polymorphisms for the development of species-specific markers. We therefore compared 21 genomes of six Tilletia species to identify DNA regions that were unique and conserved in all T. controversa isolates and had no or limited homology to other Tilletia species. A loop-mediated isothermal amplification (LAMP) assay for T. controversa was developed based on one of these DNA regions. The specificity of the assay was verified using 223 fungal samples comprising 43 fungal species including 11 Tilletia species, in particular 39 specimens of T. controversa, 92 of T. caries and 40 of T. laevis, respectively. The assay specifically amplified genomic DNA of T. controversa from pure cultures and teliospores. Only Tilletia trabutii generated false positive signals. The detection limit of the LAMP assay was 5 pg of genomic DNA per reaction. A test performance study that included five laboratories in Germany resulted in 100% sensitivity and 97.7% specificity of the assay. Genomic regions, specific to common bunt (Tilletia caries and Tilletia laevis together) are also provided.
Highlights
Tilletia controversa causing dwarf bunt of wheat is a quarantine pathogen in several countries
Common bunt of wheat is caused by Tilletia caries and T. laevis, dwarf bunt by T. controversa, and karnal bunt by T. indica
Karnal bunt is geographically restricted to a few countries namely Afghanistan, India, Iran, Mexico, Nepal, Pakistan, 1Institute for Epidemiology and Pathogen Diagnostics, Julius Kühn Institute (JKI) – Federal Research Centre for Cultivated Plants, Messeweg 11‐12, 38104
Summary
Tilletia controversa causing dwarf bunt of wheat is a quarantine pathogen in several countries. Specific to common bunt (Tilletia caries and Tilletia laevis together) are provided. Common bunt of wheat is caused by Tilletia caries and T. laevis, dwarf bunt by T. controversa, and karnal bunt by T. indica. Tilletia controversa causes dwarf bunt and is less widely distributed and restricted to certain regions of the Americas, Europe, and West Asia. Accurate distinction of dwarf bunt from common bunt and other Tilletia species, which are morphologically similar to dwarf bunt, is of high importance. It is required for efficient disease management, as well as for regulatory reasons from a wheat trading perspective. Fifteen countries, including China and Brazil, implemented quarantine measures or restrictions on the number of T. controversa teliospores per kernel in their wheat t rade[15,16,17]
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