Genetic diversity of common bunt in Europe

Summary in the original language of the document

Common bunt of wheat has re-gained attention in recent years. In this study, the pathogen population biology of the species complex Tilletia spp., causing common bunt in wheat, was studied in order to infer epidemiological patterns. Three single-spore isolates with Swedish origin were de-novo sequenced using PacBio, Sequel II technology to be used as reference genomes. For the main study, forty-four Tilleta isolates, with origin across several countries in Europe and one from Iran, were inoculated to wheat and used in virulence screening. To understand the within species diversity, the spore morphology of each isolate was determined. From each of the 44 inoculated wheat samples, one ear was selected, and three bunts were carefully collected. The DNA from each bunt was extracted and sequenced using Illumina NovaSeq 6000. The first question was to investigate the differentiation between the two species within the common bunt complex. The SNP-based data analysis revealed no differentiation between samples with different spore morphology. The results support the hypothesis that the fungal pathogens, previously divided into different species based on spore morphology, belong to the same species, Tilletia caries (syn. T. laevis). The analysis of population genetic differences revealed no differentiation between samples from Europe, whereas samples from Iran clustered as a separate group. This finding indicates that Europe potentially could be a separate epidemiological zone. Finally, the analysis identified genetic diversity within an ear, indicating the potential for multiple infections within a plant.