فهرست مطالب مشترک مهندس حسین عبدی و ایرج برنوسی

Evaluating the population structure is essential for understanding diversity patterns, choosing proper parents for crossing, accurate identification of genomic regions controlling traits, and evolutionary and kinship relationship studies. In this research, the genetic structure of a wheat population was studied in a panel consisting of 383 Iranian wheat genotypes of hexaploid (cultivars and landraces) and tetraploid species based on distance-based methods (principal component analysis and discriminant analysis of principal component). For this purpose, 16270 single nucleotide polymorphism (SNP) markers obtained by the GBS technique were used. According to the results, almost a quarter of the total variance was belonged to the diversity between populations, and the Fst coefficient between cultivars and landraces was equal to 0.15. In contrast, the above coefficient between tetraploid samples and hexaploid landraces was high and equal to 0.44. Genome D had the lowest value of Fst index and chromosome 4B showed the highest Fst coefficient, and other genetic diversity indices. Although the PCA biplot distinguished hexaploid wheat cultivars from landraces, it was unable to distinctly separate tetraploid genotypes from other genotypes. Accurate evaluation of the population structure with the DAPC method was able to identify and separate the predetermined successfully groups, suggesting that the DAPC approach maximizes the differentiation between groups and minimizes the changes within the group. Partial admixture between cultivars and landraces of hexaploid wheat can be related to gene exchange between these two groups or perhaps their wrong labeling at the time of collection. In general, the results of this study provided valuable information about the genetic differentiation of Iranian tetraploid and hexaploid wheat, which can be used in future wheat breeding programs. Further, protecting these genotypes in gene banks is necessary for different strategies.

Rapid screening of plant germplasm in the early stages of growth and determining the genetic basis of wheat leaf wilting index at the seedling stage is necessary for wheat breeding programs. In the present research, leaf wilting index for 290 Iranian bread wheat genotypes, including; 90 cultivars and 200 landraces were studied under drought stress conditions at the seedling stage in 2021 in research greenhouse of faculty agriculture of Urmia University, Urmia, Iran. The results showed that there was variation between the studied genotypes for leaf wilting index, and the landraces had significantly 12% more wilting scores than cultivars. This can be attributed to direct or indirect selection by breeders. The leaf wilting index of about 9% of cultivars and 3% of landraces were identified in drought stress tolerant group. GWAS had nearly the same results as general lineare model and MLM methods. Chromosomes 3B, 2A, 7B, 1A, 3A, 4B, 5B, 6A and 6B, respectively, had the highest number of marker-trait associations in the entire population which explained the phenotypic variation of the trait from 6 to 20%. Annotation of significant markers confirmed the results of GWAS analysis and showed that five markers on chromosomes 1A, 2A, 3A and 7B were aligned with different genes involved in drought stress tolerance. An integral component of membrane, protein phosphorylation, methyltransferase activity and zinc ion binding were part of the molecular functions and biological processes of the identified genes. The findings of this research provide a deep insight into the variation of leaf wilting traits in Iranian bread wheat germplasm under drought stress conditions, which can be used as selction criterium in the national bread wheat improvement programs.