Population structure of Pyrenophora teres f. teres barley pathogens from different continents

Abstract

Net-form net blotch disease caused by Pyrenophora teres f. teres (Ptt) results in significant yield losses to barley industries. Up-to-date knowledge of the genetic diversity and structure of pathogen populations is critical for better understanding the disease epidemiology and unravelling pathogen survival and dispersal mechanisms. Thus, this study investigated long distance dispersal and adaptation by analysing the genetic structure of 250 Ptt isolates collected from Australia, Canada, Hungary and Republic of South Africa (RSA), and historical isolates from Canada, Denmark, Japan and Sweden. The population genetic structure detected by discriminant analysis of principal component, using 5890 Diversity Arrays Technology (DArT) markers, revealed the presence of four clusters. Two of these contained isolates from all regions, and all isolates from RSA were grouped in these two. Australia and Hungary showed three clusters each. One of the Australian clusters contained only Australian isolates. One of the Hungarian clusters contained only Hungarian isolates and one Danish isolate. STRUCTURE analysis indicated that some isolates from Australia and Hungary shared recent ancestry with RSA, Canada and historical isolates and were thus admixed. Subdivisions of the Neighbor-joining network indicated that isolates from distinct countries were closely related, suggesting multiple introduction events conferred genetic heterogeneity in these countries. Through a Neighbor-joining analysis and amplification with form-specific DNA markers two hybrid isolates, CBS 281.31 from Japan and H-919 from Hungary collected in 1931 and 2018, respectively, were detected. These results provide a foundation for exploring improved management of disease incursions and pathogen control through strategic deployment of resistances.