Jonathan D. Beutler
Ph.D. Student
Michael Smith Laboratories, The University of British Columbia
Vancouver, BC, CANADA
Samuel Holden
Post-doctoral Fellow
Faculty of Agricultural, Life and Environmental Science, University of Alberta
Vancouver, British Columbia, Canada
Marwa Laribi
Post-Doctoral Fellow
Faculty of Agricultural, Life and Environmental Science, University of Alberta
Edmonton, Alberta, Canada
Zyré Aubrey-Herbert
Ph.D. Student
Faculty of Agricultural, Life and Environmental Science, University of Alberta
Edmonton, Alberta, Canada
Stephen Strelkov
Professor
Faculty of Agricultural, Life and Environmental Science, University of Alberta
Edmonton, Alberta, Canada
Gurcharn Brar
Assistant Professor
Faculty of Agricultural, Life and Environmental Science, University of Alberta
Edmonton, Alberta, Canada
Marco Todesco
Assistant Professor
Michael Smith Laboratories, The University of British Columbia
Vancouver, Alberta, Canada
Effective genomic surveillance for fungal pathogens requires a robust understanding of the global population structure. Wheat tan spot presents a significant threat to global nutrition but does not garner the research investment of more virulent fungal pathogens, with limited genome resources published in the public domain. Population genomic analyses of 71 novel Pyrenophora tritici-repentis sequences from the Canadian prairies (AB, MB, and SK), Northern Africa (Tunisia and Algeria), and the Near East (Iran and Azerbaijan) reveal two geographically segregated population clusters. Whole-genome SNP discovery identified 34,368 high-confidence variable sites after stringent filtering for quality (Phred > 40), missing data (AN > 40), minor allele frequency (MAF > 0.05), and removal of singletons (AC > 1). ADMIXTURE modeling supported two ancestral populations, with the lowest cross-validation error (CVerror = 0.7502) at K = 2. Phylogenetic reconstruction using RAxML-NG (100 bootstraps) predicted a tree topology corroborating clustering patterns inferred independently through ADMIXTURE. Principal component analysis (PCA) performed with PLINK2 further validated this structure: isolates from Northern Africa, Azerbaijan, and the eastern prairie provinces (SK and MB) formed a tight cluster along PC1. Three distinct clusters of Iranian and western prairie (AB) isolates grouped oppositely on PC1 but showed greater dispersion across PC2. These findings suggest limited recombination between ancestral lineages following multiple P. tritici-repentis introductions to the Canadian prairies.