Evaluating space-mutagenized Sumai 3 lines for disease resistance, agronomic traits, and quality: screening elite germplasm with Fhb1 and Yr30 markers

Wheat production in the middle and lower Yangtze River region of China is persistently threatened by Fusarium head blight (FHB), stripe rust, leaf rust, and powdery mildew. Sumai 3, a widely deployed FHB-resistant cultivar carrying Fhb1 , remains a cornerstone parent in regional breeding, yet its narrow genetic base constrains simultaneous improvement of broad-spectrum resistance and end-use quality. Here we evaluated 504 M₅ lines derived from Sumai 3 via space mutagenesis for resistances to all four diseases, agronomic traits, and flour quality, and profiled the Fhb1 and Yr30 markers. The mutant population exhibited a striking divergence in adult-plant resistance: stripe rust resistance increased markedly (80.9% resistant lines), whereas FHB resistance declined sharply (25.9% resistant lines). Multi-stage screening identified 30 elite lines; six maintained stable high resistance to stripe rust and powdery mildew across three consecutive years. One line, SM3-30-6-13-22-50, met super-strong gluten standards (protein 16.02%, stability 31.4 min) while retaining stable disease resistance. Marker assays detected Fhb1 in 10 lines and Yr30 in 6 lines; notably, Yr30 was absent in the original line but present in several mutants, suggesting possible perturbation in the 3BS region. Effect-size analysis showed no significant negative effects of either gene on agronomic or quality traits. These elite lines and the documented resistance trade-off provide valuable germplasm and a practical reference for wheat breeding targeting combined multi-disease resistance and high quality.