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Stripe rust is one of the most important diseases of wheat and can cause significant yield losses. The emergence of new virulent races has rendered many resistance genes ineffective, highlighting the need for continuous efforts to discover effective resistance sources and genes. The present study aimed to identify novel genetic resources for resistance to stripe rust by evaluating two germplasm sets consisting of 230 and 253 bread wheat accessions from the National Plant Gene Bank of Iran, originating from different countries. These accessions were evaluated in a stripe rust nursery at the Karaj experimental field by measuring resistance traits, including infection type, disease severity, and coefficient of infection. The results showed that 1.6% of the first set and 33.99% of the second set exhibited resistant or immune responses. Accessions with superior resistance responses from each set were re-evaluated in the following year. Subsequently, those accessions demonstrating stable resistance across two years were tested in the seedling stage under greenhouse conditions against various virulent pathotypes. The selected genetic materials from the first and second sets displayed seven and fourteen different reaction patterns to the pathotypes, respectively. Considering the virulence factors of the pathotypes, the presence of one or combinations of Yr1, Yr4, Yr5, Yr10, Yr15, Yr24, YrSP, and YrSU genes was postulated in accessions KC8592, KC8694, KC8893, KC8894, KC8899, and KC8900. Likewise, the presence of Yr1, Yr4, Yr5, Yr10, Yr15, Yr24, and YrSP genes was suggested in accessions KC8904, KC8905, KC8906, KC8910, KC8973, KC9005, KC9007, KC9013, KC9029, KC9032, KC9038, KC9144, KC9152, KC9208, KC9209, KC9272, and KC9281. Additionally, the presence of Yr8 and Yr27 resistance genes was likely in KC8543, KC8660, KC8719, and KC8891; Yr3 in KC8953, KC8988, KC9004, KC9006, KC9031, KC9119, KC9150, KC9178, KC9202, KC9284, KC9301, and KC9330; Yr8 in KC9116 and KC9305; Yr26 in KC9010; Yr27 in KC8907; and YrSD in KC9027. A considerable number of accessions were also identified as potentially harboring novel, unknown resistance genes outside the known set of differential genes or exhibiting adult plant resistance. Due to the importance of Yr5 and Yr15 genes in providing durable and effective resistance, their presence was further verified in selected accessions using specific molecular markers. The results confirmed the presence of both Yr5 and Yr15 in accession KC9272 and the presence of Yr15 in accessions KC8694, KC8719, KC8846, KC8899, KC8900, KC8904, KC8905, KC8973, KC9116, KC9121, KC9144, KC9154, KC9209, and KC9307. Overall, the findings led to the identification of diverse resistance resources, and the superior genetic materials identified can be utilized in breeding programs for stripe rust resistance.
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