Fhb7 is a major gene that was transferred from Thinopyrum ponticum to chromosome 7D of wheat (Triticum aestivum) and confers resistance to both Fusarium head blight (FHB) and Fusarium crown rot (FCR). However, Fhb7 is tightly linked to the PSY-E2 gene, which causes yellow flour, limiting its application in breeding. To break this linkage, marker K-PSY was developed for tagging PSY-E2 and used with Fhb7 markers to identify recombination between the two genes. Screening 21,000 BC₁F₂ backcross progeny (Chinese Spring ph1bph1b^*2/SDAU 2028) revealed two Fhb7⁺ wheat-Tp7el₂L lines, Shannong 2–16 and Shannong 16–1, that carry a desired truncated Fhb7⁺ translocation segment without PSY-E2. The two lines show levels of resistance to FHB and FCR similar to those of the original translocation line SDAU 2028, but have white flour. To facilitate Fhb7 use in wheat breeding, STS markers were developed and used to isolate Fhb7 on a truncated Tp7el₂ translocation segment. Near-isogenic lines carrying the Fhb7⁺ segment were generated in the backgrounds of three commercial cultivars, and Fhb7⁺ lines showed increased FHB and FCR resistance without yield penalty. The breakage of the tight linkage between Fhb7 and PSY-E2 via homoeologous recombination provides genetic resources for improvement of wheat resistance to FHB and FCR and permit the large-scale deployment of Fhb7 in breeding using marker-assisted selection.

Powdery mildew, caused by Blumeria graminis f. sp. tritici (Bgt), is one of the most devastating diseases of common wheat (Triticum aestivum L.). The wheat line 92145E8-9 is immune to Bgt isolate E09. Genetic analysis reveals that the powdery mildew resistance in 92145E8-9 is controlled by a single dominant gene, temporarily designated Ml92145E8-9. Bulked-segregant analysis (BSA) with simple sequence repeat (SSR) markers indicates that Ml92145E8-9 is located on chromosome 2AL. According to the reactions of 92145E8-9, VPM1 (Pm4b carrier), and Lankao 906 (PmLK906 carrier) to 14 Bgt isolates, the resistance spectrum of 92145E8-9 differs from those of Pm4b and PmLK906, both of which were previously localized to 2AL. To test the allelism among Ml92145E8-9, Pm4b and PmLK906, two F₂ populations of 92145E8-9 × VPM1 (Pm4b) and 92145E8-9 × Lankao 906 (PmLK906) were developed in this study. Screening of 784 F₂ progeny of 92145E8-9 × VPM1 and 973 F₂ progeny of 92145E8-9 × Lankao 906 for Bgt isolate E09 identified 37 and 19 susceptible plants, respectively. These findings indicated that Ml92145E8-9 is non-allelic to either Pm4b or PmLK906. Thus, Ml92145E8-9 is likely to be a new powdery mildew resistance gene on 2AL. New polymorphic markers were developed based on the collinearity of genomic regions of Ml92145E8-9 with the reference sequences of the International Wheat Genome Sequencing Consortium (IWGSC). Ml92145E8-9 was mapped to a 3.6 cM interval flanked by molecular markers Xsdauk13 and Xsdauk682. This study also developed five powdery mildew-resistant wheat lines (SDAU3561, SDAU3562, SDAU4173, SDAU4174, and SDAU4175) using flanking marker-aided selection. The markers closely linked to Ml92145E8-9 would be useful in marker-assisted selection for wheat powdery mildew resistance breeding.

Gliadins are the major components of storage proteins in wheat and play an important role in determining the extensibility properties of dough. In the present work, six novel full-length γ-gliadin genes were cloned from the C genome of Aegilops markgrafii using a PCR-based strategy. Analysis of the deduced amino acid sequences showed that the cloned genes had primary structures that were similar, but not identical, to published γ-gliadins from other wheat-related species. The lengths of the open reading frames (ORFs) ranged from 909 to 963bp, and the repetitive and glutamine-rich domains were mainly responsible for the size of the proteins. An extra cysteine residue was present in the repetitive domain of sequence JX566513. All amino acid sequences of γ-gliadin genes from Ae. markgrafii were searched for the five peptides identified as T cell stimulatory epitopes in celiac disease (CD) patients. Peptide Gliγ-3 was present in sequences JX566513 and JX566514. Peptide Gliγ-5 was present only in JX566513. The other γ-gliadins contained no toxic epitopes. These results provide information to better understand the use of Ae. markgrafii in wheat breeding and the evolutionary relationship of the γ-gliadin genes in Ae. markgrafii and other Triticeae species.

The rich genetic variation preserved in collections of Aegilops tauschii can be readily exploited to improve common wheat using synthetic hexaploid wheat lines. However, hybrid necrosis, which is characterized by progressive death of leaves or plants, has been observed in certain interspecific crosses between tetraploid wheat and Ae. tauschii. The aim of this study was to construct a fine genetic map of a gene (temporarily named NetJingY176) conferring hybrid necrosis in Ae. tauschii accession Jing Y176. A triploid F₁ population derived from distant hybridization between Ae. tauschii and tetraploid wheat was used to map the gene with microsatellite markers. The newly developed markers XsdauK539 and XsdauK561 co-segregated with NetJingY176 on chromosome arm 2DS. The tightly linked markers developed in this study were used to genotype 91 Ae. tauschii accessions. The marker genotype analysis suggested that 49.45% of the Ae. tauschii accessions carry NetJingY176. Interestingly, hybrid necrosis genotypes tended to appear more commonly in Ae. tauschii ssp. tauschii than in Ae. tauschii ssp. strangulata.