Population genetic analysis reveals host-driven subgroup structuring and sexual recombination in Pyrenophora teres, highlighting risks for barley resistance durability.
Key Points
Characterize the genetic diversity, population structure, and evolutionary dynamics of Pyrenophora teres infecting spring barley in Norway relative to global collections.
Analyzed genetic diversity and structure across 339 Norwegian isolates and 61 globally collected isolates using Bayesian clustering and principal coordinate analysis.
Integrated local isolates with two published global datasets and conducted a genome-wide association study to identify markers linked to host variety specialization.
Evaluated spatial and temporal population differentiation over a 20-year span and assessed mating type ratios across collection regions.
Identified 325 (95.9%) P. teres f. teres (Ptt), 8 (2.4%) P. teres f. maculata (Ptm), and two putative hybrid isolates in Norway, with Ptt resolving into two subgroups shaped by host spike row-type and variety.
Mating types displayed an approximate 1:1 ratio across regions with high multilocus genotype frequencies and an absence of geographic differentiation, demonstrating extensive gene flow and active sexual reproduction.
Identified significant temporal differentiation between isolates sampled 20 years apart, and genome-wide association mapping revealed three markers on chromosomes 5 and 9 associated with host variety, with the chromosome 5 locus overlapping known virulence loci.