Morphological and Molecular Characterization of Septoria tritici Blotch Pathogen (Zymoseptoria tritici) Isolates from Durum Wheat

Abstract

Septoria tritici blotch caused by Zymoseptoria tritici is one of the most destructive foliar diseases affecting durum wheat production worldwide, leading to substantial reductions in grain yield and quality under favorable environmental conditions. The disease is characterized by chlorotic and necrotic leaf lesions containing pycnidia, which reduce photosynthetic activity and accelerate premature leaf senescence. Accurate identification and characterization of the pathogen are essential for understanding its variability and developing effective disease management strategies. The present study was conducted to investigate the morphological and molecular characteristics of Z. tritici isolates associated with Septoria tritici blotch disease in durum wheat-growing regions. Diseased wheat leaf samples exhibiting characteristic symptoms were collected from infected fields, and fungal isolates were obtained using standard isolation and culturing techniques. Morphological characterization was performed based on colony appearance, pigmentation, growth pattern, and microscopic examination of pycnidiospores and reproductive structures. Molecular identification was carried out using polymerase chain reaction (PCR) amplification and sequencing of conserved genomic regions, followed by phylogenetic analysis to determine genetic relationships among isolates. The results confirmed the association of Z. tritici with symptomatic durum wheat leaves collected from surveyed areas. Considerable morphological variability was observed among isolates in colony texture, sporulation, and pigmentation characteristics. Molecular analysis revealed significant genetic diversity within the pathogen population, indicating the presence of multiple genetically distinct isolates infecting durum wheat. Phylogenetic analysis demonstrated close relationships between the obtained isolates and previously reported Z. tritici strains from major wheat-growing regions worldwide. The findings provide valuable insights into the diversity and identification of Z. tritici populations affecting durum wheat. Understanding the morphological and molecular variability of this pathogen is important for improving disease diagnosis, resistance breeding programs, and integrated disease management strategies aimed at reducing the impact of Septoria tritici blotch on wheat productivity.