Phenotypic and cultural diversity of zymoseptoria tritici causing septoria leaf blotch in Ethiopian wheat.

Septoria leaf blotch caused by Zymoseptoria tritici (Z. tritici) is indeed a major constraint to global wheat production, reduces wheat yield and quality. This study aimed to evaluate the phenotypic and cultural diversity of Z. tritici isolates. A total of 67 isolates were collected from major wheat-growing hotspot areas in Ethiopia. Molecular confirmation of the isolates was performed using PCR with specific markers (ST2E4, ST1G7, and tcc-0009). Among the collected samples, 45.5% originated from North Shoa, while only 3% were obtained from East Gojam, indicating uneven distribution across regions. The isolates exhibited considerable variation in colony morphology, such as color, shape, texture, and growth patterns. Most colonies showed raised elevation and undulate margins. Significant variability was observed in growth and sporulation traits. Isolate H266 showed the largest mean colony diameter (29.33 mm), whereas Ag3p had the smallest (7.33 mm). The highest conidial concentration (8.36 × 10⁶ cells mL⁻¹) was recorded in isolate SW2 from Siyadebrina Wayu, while the lowest (1.5 × 10⁵ cells mL⁻¹) was observed in isolate Ag3p from Abbichunagnea Wereda. Overall, substantial phenotypic and microscopic variability was detected among Ethiopian Z. tritici isolates. These findings provide important insights for improving disease management strategies and support the development of wheat cultivars with durable resistance.