Genetic structure of a Pyrenophora teres f. teres population over time in an Australian barley field as revealed by DArT markers

Net form of net blotch caused by Pyrenophora teres f. teres (Ptt) is a major foliar disease of barley (Hordeum vulgare) worldwide. Knowledge of the evolution of P. teres f. teres pathogen populations is important for development of durable host-plant resistance. This study was conducted to investigate changes in genetic structure of a Ptt population within a barley field during three cropping years. The susceptible barley cultivar Henley was inoculated with Ptt isolate NB050. Leaf samples were collected during the year 2013–2015 and 174 single spore Ptt isolates stored. Genotyping using Diversity Arrays Technology markers identified that 25% of isolates were clones of the inoculated isolate and 75% of isolates were multi-locus genotypes (MLGs) differing from the original inoculated genotype. The novel genotypes likely originated from a combination of wind-borne spores from neighbouring fields, infected seed and sexual recombination in the field. The rapid change in the genotypic composition of the Ptt population in this study suggests adaptive potential of novel genotypes and demonstrates the need for barley breeders to use multiple sources of host-plant resistance to safeguard against resistance being overcome. This article is protected by copyright. All rights reserved.