Virulence assessment of Australian <i>Pyrenophora tritici‐repentis</i> isolates

Abstract The virulence of 57 Australian isolates Pyrenophora tritici ‐ repentis (Ptr), a necrotrophic fungal pathogen responsible for the major wheat disease tan spot, was assessed through plant infection assays. Isolates collected from northern, southern, and western wheat‐cropping regions Australia were evaluated against 16 bread cultivars under controlled growth conditions. Following infection, panel displayed varying symptoms ranging tiny necrotic specks to spreading chlorotic lesions. Analysis variance indicated that cultivar exhibited greater effect on response, explaining 62.7% variation, in comparison isolate (10.4%). interaction between statistically significant attributed 9.8% total variation. All Ptr examined able cause disease, but did not display clear distinction investigated, instead showing subtle differences aggressiveness. Based responses, there no obvious pattern aggressiveness cropping region. Some cultivars, such as Hydra, an effective level resistance relation tested. found possess ToxA effector gene lack ToxB gene. expression up‐regulated at 3 days postinfection both ToxA‐sensitive ‐insensitive independent ToxA– Tsn1 recognition.