There are two recognised forms of the disease net blotch of barley. The net form of net blotch is caused by P. teres f. teres (PTT) while the spot form is caused by P. teres f. maculata (PTM). In this study, amplified fragment length polymorphism analysis was used to investigate the genetic diversity and population structure of 60 PTT and 64 PTM isolates collected across Australia (66 isolates) and in the south-western Cape of South Africa (58 isolates). For comparison, Pyrenophora tritici-repentis, Exserohilum rostratum and Bipolaris sorokiniana samples were also included in the analyses. Both distance- and model-based cluster analyses separated the PTT and PTM isolates into two strongly divergent genetic groups. Significant variation was observed both among the South African and Australian populations of PTT and PTM and among sampling locations for the PTT samples. Results suggest that South Africa and Australia harbour different biotypes for each form of P. teres. The isolates collected for this study will form the basis of an on-going collection available for future studies
