Wheat cultivar Shaannong 33 (SN33) has remained highly resistant to stripe rust in the field since its release in 2009. To unravel the genetic architecture of stripe rust resistance, seedlings of 161 recombinant inbred lines (RILs) from the cross Avocet S × SN33 were evaluated with two isolates (PST-Lab.1 and PST-Lab.2) of the stripe rust pathogen (Puccinia striiformis f. sp. tritici) in the greenhouse, and the RILs were evaluated in naturally or artificially inoculated field sites during two cropping seasons. The RILs and parents were genotyped with the wheat 55K single-nucleotide polymorphism array. Three genomic regions conferring seedling resistance were mapped on chromosomes 1DS, 2AS, and 3DS, and four consistent quantitative trait loci (QTL) for adult-plant resistance (APR) were detected on 1BL, 2AS, 3DL, and 6BS. The 2AS locus conferring all-stage resistance was identified as the resistant gene Yr17 located on 2NS translocation. The QTL identified on 1BL and 6BS likely correspond to Yr29 and Yr78, respectively. An APR QTL on 3DL explaining 5.8 to 12.2% of the phenotypic variation is likely to be new. Molecular marker detection assays with the 2NS segment (Yr17), Yr29, Yr78, and QYrsn.nwafu-3DL on a panel of 420 current Chinese wheat cultivars and breeding lines indicated that these genes were present in 11.4, 7.6, 14.8, and 7.4% of entries, respectively. The interactions among these genes and QTL were additive, suggesting their potential value in enhancing stripe rust resistance breeding materials as observed in the resistant parent. In addition, we also identified two leaf necrosis genes, Ne1 and Ne2; however, the F₁ plants from cross Avocet S × SN33 survived, indicating that SN33 probably has another allele of Ne1 which allows seed to be harvested.

Fusarium head blight (FHB) is a devastating disease that occurs in warm and humid environments. The German wheat ‘Centrum’ has displayed moderate to high levels of FHB resistance in the field for many years. In this study, an F_6:8 recombinant inbred line (RIL) population derived from cross ‘Centrum’ × ‘Xinong 979’ was evaluated for FHB response following point inoculation in five environments. The population and parents were genotyped using the GenoBaits Wheat 16 K Panel. Stable quantitative trait loci (QTL) associated with FHB resistance in ‘Centrum’ were mapped on chromosome arms 2DS and 5BS. The most effective QTL, located in 2DS, was identified as a new chromosome region represented by a 1.4 Mb interval containing 17 candidate genes. Another novel QTL was mapped in chromosome arm 5BS of a 5BS to 7BS translocation chromosome. In addition, two environmentally sensitive QTL were mapped on chromosome arms 2BL from ‘Centrum’ and 5AS from ‘Xinong 979’. Polymorphisms of flanking phenotypic variance explained (PVE) markers (allele-specific quantitative PCR [AQP]) AQP-6 for QFhb.nwafu-2DS and 16K-13073 for QFhb.nwafu-5BS were validated in a panel of 217 cultivars and breeding lines. These markers could be useful for marker-assisted selection (MAS) of FHB resistance and provide a starting point for fine mapping and marker-based cloning of the resistance genes.