Pathotype Analysis of Blumeria graminis f. sp. tritici and Characterization of Some Powdery Mildew Resistance Genes in Egyptian Wheat Genotypes

Ensuring sustainable wheat production is crucial for food security, particularly in regions facing plant diseases and environmental challenges. In the Middle East, wheat powdery mildew, caused by Blumeria graminis f. sp. tritici, significantly threatens yields and quality, making it essential to comprehend local pathotype virulence and resistance genes for effective disease management. Therefore, 252 infected leaves were sampled from cultivated bread wheat genotypes in Egypt Delta region during 2024–2025 growing seasons. Forty-one powdery mildew monogenic lines (Pm) and twelve new bread wheat genotypes were evaluated at seedling and adult stages. Pathotype analysis identified six pathotypes in 2024 (IOEE most common, 22.91%) and four in 2025 (POKE dominant, 34.25%). Virulence diversity declined significantly: Shannon diversity decreased from 5.90 to 3.73, and Simpson diversity decreased from 5.81 to 3.58, indicating reduced pathotype complexity. No virulence was detected against Pm11, Pm13, Pm24, Pm25, Pm29, Pm32, Pm34, Pm35, Pm36, Pm37, Pm43, NCA9, and MIAB10 genes. PERMANOVA analysis showed no significant compositional difference between seasons (R2 = 0.112, p = 0.481), with low genetic differentiation (mean character difference = 0.1894; Roger’s distance = 0.1914). Sakha96 wheat genotype displayed complete resistance at both growth stages, while Misr4, Misr5, Sakha95, Sids15, and Gemmeiza13 showed adult-stage resistance only in both seasons. Molecular analysis revealed that Pm24, Pm35 and Pm37 were absent in all genotypes. Pedigree analysis demonstrated Pm35 and Pm37 share common ancestral origins across Egyptian wheat germplasm. So, these resistant genotypes and broadly effective resistance genes provide valuable resources for breeding durable powdery mildew resistance in Egyptian wheat.