Both Mating types of Phaeosphaeria (anamorph Stagonospora) nodorum are Present in Western Australia

Phaeosphaeria (anamorph Stagonospora) nodorum is the most serious fungal pathogen of wheat in the West Australian (WA) wheat belt and is a diallelic heterothallic loculoascomycete. Its population genetics has received considerable attention. A recent study, which sampled isolates from diverse locations worldwide, has indicated that the mating-type idiomorph MAT1-1 is considerably more frequent than MAT1-2 in many populations. To investigate this, we developed PCR primers that amplify each idiomorph. In a sample of 23 isolates cultured from ascospores collected in the field, nine amplified DNA with the MAT1-1 primers and 14 amplified DNA with the MAT1-2 primers. The virulence of a MAT1-2 isolate was comparable with MAT1-1 isolates. Although these sample sizes are small, we suggest that this result is consistent with the presence of equal numbers of both mating types in populations of ascospores in WA.