Thesis (M.Sc)-Cairo University, 2025.

Bibliography: pages 114-138.

This study was conducted from 2019 to 2020 at Merchouch (Morocco)
and Izmir (Turkey), and from 2022 to 2023 at Sakha and Sids (Egypt), to
investigate the genetic variability of stripe rust resistance in spring bread
wheat. Stripe rust, caused by Puccinia striiformis f. sp. tritici, is a major biotic
stress affecting wheat (Triticum aestivum) production worldwide. Identifying
resistant wheat genotypes and their associated genomic regions is crucial for
breeding programs aimed at improving stripe rust resistance. In this study, a
panel of 154 spring bread wheat genotypes from the International Center for
Agricultural Research in the Dry Areas (ICARDA) was evaluated across the
four locations. Disease severity was assessed under natural field infection at
the adult plant stage using the coefficient of infection (CI) as a quantitative
measure of resistance. Genomic DNA was genotyped using 17,692 high-
quality single-nucleotide polymorphism (SNP) markers, and genome-wide
association studies (GWAS) were performed to identify significant marker–
trait associations (MTAs) related to stripe rust tolerance. The mixed linear
model (MLM), accounting for population structure and relatedness, was
applied to each environment. A total of 136 significant MTAs were identified
(−log10 (p) > 3.0), with the strongest associations located on chromosomes
2A, 3B, 4A, 5B, and 7A. Several MTAs were found near known resistance
genes, including Yr18 and Yr57, while others appeared to represent novel loci.
These findings highlight the polygenic nature of stripe rust tolerance in wheat
and the influence of environmental variation on tolerance expression. The
results provide valuable insights into the genetic architecture of tolerance and
offer potential targets for marker-assisted breeding.

أُجريت هذه الدراسة خلال عامي 2019–2020 في مرشوش (المغرب) وإزمير (تركيا)، وخلال عامي 2022–2023 في سخا وسدس (مصر)، بهدف دراسة التباين الوراثي لمقاومة صدأ الأوراق المخططة في قمح الخبز الربيعي. يُعد صدأ الأوراق المخططة، المتسبِّب عن فطر Puccinia striiformis f. sp. tritici، من أهم عوامل الإجهاد الحيوي التي تؤثر في إنتاجية القمح (Triticum aestivum) عالمياً. ولذلك يُعد تحديد الطرز الوراثية المقاومة ومناطق الجينوم المرتبطة بها أمراً بالغ الأهمية لبرامج التربية الهادفة إلى تحسين مقاومة القمح لهذا المسبب المرضي.في هذه الدراسة، جرى تقييم مجموعة مكونة من 154 طرازاً وراثياً من قمح الخبز الربيعي التابعة للمركز الدولي للبحوث الزراعية في المناطق الجافة (إيكاردا) عبر المواقع الأربعة.

Issues also as CD.

Text in English and abstract in Arabic & English.