https://doi.org/10.37229/fsa.fjas.2025.11.28

Six Egyptian bread wheat (Triticum aestivum L.) cultivars were evaluated at the Kafr El-Hamam Agricultural Research Station, Sharqia Governorate, Egypt, during the 2024 and 2025 growing seasons to assess their response to stripe rust under artificial inoculation. The study aimed to detect and introgress the yellow rust resistance gene Yr15 into six parental cultivars; Giza-171, Gemmeiza-11, Sids-12, Misr-1, Misr-2, and Sids-14 and their corresponding F₁ and F₂ hybrids. The cultivars displayed variable reactions to stripe rust, with Giza-171 and Sids-14 exhibiting slow-rusting characteristics, whereas Gemmeiza-11, Sids-12, Misr-1, and Misr-2 showed rapid disease progression. The area under the disease progress curve (AUDPC) closely reflected disease severity across genotypes. Yr15 was not detected in any of the parental cultivars. Segregation patterns observed in the F₂ populations of crosses with Yr15 confirmed its absence in all tested cultivars. Broad-sense heritability exceeded 98%, indicating strong genetic control and the feasibility of selecting resistant plants as early as the F₂ generation; however, delayed selection is preferable due to the considerable dominance effects influencing resistance expression. Yield-related traits showed superior mean values in the F₂ populations compared with their respective parents, reflecting favorable recombination. These findings underscore the need for breeders to diversify resistance sources rather than relying solely on complete or race-specific resistance genes, thereby strengthening long-term resilience against stripe rust.