Mekonnen, Tilahun (PhD)Mebratu, Taye2022-03-172023-11-182022-03-172023-11-182021-07-12http://etd.aau.edu.et/handle/12345678/30634Zymoseptoria tritici the causative agent of Septoria tritici blotch (STB), is one of the most economically damaging disease of wheat worldwide. Genetic resistance is a suitable, economical and environmentally safe strategy to control the disease. Knowledge of the genetic structure of the pathogen is vital for designing best management strategy against STB. The present study aimed to investigate the genetic diversity of Z. tritici in Ethiopia at a single field scale using simple sequence repeat (SSR) markers. A total of 200 naturally STB infected wheat leaves were collected from 10 plots of unsprayed single field at Holetta Agricultural Research Center. A total of 147 single-spore derived Z. tritici isolates were subjected to genetic diversity analysis using ten SSR loci. All the tested loci were polymorphic, and highly informative. Different diversity parameters were executed, and highlighted with the number of alleles, gene diversity (0.82), and polymorphic information content ranged from 5-11, 0.71- 0.88 and 0.67 -0.87 with overall mean of 9 , 0.82, and 0.80, respectively. Hierarchical analysis of molecular variance revealed moderate (PhiPT= 0.13) genetic differentiation where the within population genetic variation accounted for 87% of the total variation 4.18. The variation among population accounted only for 13% of the total genetic variation, likely due to the presence of high (Nm = 3.48) gene flow. The neighbor joining, UPGMA and PCoA failed in sharply grouping the populations into their corresponding sampled plots, confirming the presence of high gene flow. Moreover, the Bayesian-model based structure analysis weakly inferred four sub-groups (K= 4) confirming the weak population structuring with high degree of genetic admixture. Therefore, the study confirmed that Z. tritici population shows high genetic variation even in a single field, suggesting need to use integrated disease management strategies to control the disease and also give especial focus for resistance breading to involve pyramiding of several genes that can provide broad spectrum resistance.enSeptoria Tritici BlotchMicrosatellitePolymorphismWheatThesis