Pathogen diversity and screening for minor gene resistance to Pyrenophora teres f. teres in barley and its use for plant breeding

The diversity of isolates of Pyrenophora teres f. teres , the causal agent of net form net blotch (NFNB), was studied using a set of 24 Australian barley varieties. Screening at the seedling and adult plant stages was used to detect and demonstrate the relative importance of resistance at both growth stages. The results showed that almost all isolates vary in virulence as expected from a sexually reproducing population and the measure of diversity is mainly limited by the number of differential varieties/lines used in the tests. The recent history of virulence changes in the South Australian pathogen population is described and illustrated through NFNB pathotype tests. Pathotype evidence for durable resistance in commercial varieties is demonstrated. The methods used for pathotype analysis are applicable for the breeding and selection of durable resistance for NFNB in barley.