Powdery mildew, caused by Blumeria graminis f. sp. tritici, is one of the most severe wheat diseases.  Mining powdery mildew resistance genes in wheat cultivars and their appliance in breeding program is a promising way to control this disease.  Genetic analysis revealed that a single dominant resistance gene named PmTm4 originated from Chinese wheat line Tangmai 4 confers resistance to prevailing isolates of B. graminis f. sp. tritici isolate E09.  Detailed comparative genomics analyses helped to develop closely linked markers to PmTm4 and a fine genetic map was constructed using large F₂ population, in which PmTm4 was located into a 0.66-cM genetic interval.  The orthologous subgenome region of PmTm4 in Aegilops tauschii was identified, and two resistance gene analogs (RGA) were characterized from the corresponding sequence scaffolds of Ae. tauschii draft assembly.  The closely linked markers and identified Ae. tauschii orthologs in the mapping interval provide an entry point for chromosome landing and map-based cloning of PmTm4.

Pre-harvest sprouting (PHS) occurs frequently in most of the wheat cultivation area worldwide, which severely reduces yield and end-use quality, resulting in substantial economic loss.  In this study, quantitative trait loci (QTL) for PHS resistance were mapped using an available high-density single nucleotide polymorphism (SNP) and simple sequence repeat (SSR) genetic linkage map developed from a 269 recombinant inbred lines (RILs) population of Yanda 1817×Beinong 6.  Using phenotypic data on two locations (Beijing and Shijiazhuang, China) in two years (2012 and 2013 harvesting seasons), five QTLs, designated as QPhs.cau-3A.1, QPhs.cau-3A.2, QPhs.cau-5B, QPhs.cau-4A, and QPhs.cau-6A, for PHS (GP) were detected by inclusive composite interval mapping (ICIM) (LOD≥2.5).  Two major QTLs, QPhs.cau-3A.2 and QPhs.cau-5B, were mapped on 3AL and 5BS chromosome arms, explaining 6.29–21.65% and 4.36–5.94% of the phenotypic variance, respectively.  Precise mapping and comparative genomic analysis revealed that the TaVp-1A flanking region on 3AL is responsible for QPhs.cau-3A.2.  SNP markers flanking QPhs.cau-3A.2 genomic region were developed and could be used for introgression of PHS tolerance into high yielding wheat varieties through marker-assisted selection (MAS).

Powdery mildew, caused by Blumeria graminis f. sp. tritici, is one of the most devastating wheat diseases. Wild emmer wheat (Triticum turgidum ssp. dicoccoides) is a promising source of disease resistance for wheat. A powdery mildew resistance gene conferring resistance to B. graminis f. sp. tritici isolate E09, originating from wild emmer wheat, has been transferred into the hexaploid wheat line WE4 through crossing and backcrossing. Genetic analyses indicated that the powdery mildew resistance was controlled by a single dominant gene, temporarily designated MlWE4. By mean of comparative genomics and bulked segregant analysis, a genetic linkage map of MlWE4 was constructed, and MlWE4 was mapped on the distal region of chromosome arm 5BL. Comparative genetic linkage maps showed that genes MlWE4, Pm36 and Ml3D232 were co-segregated with markers XBD37670 and XBD37680, indicating they are likely the same gene or alleles in the same locus. The co-segregated markers provide a starting point for chromosome landing and map-based cloning of MlWE4, Pm36 and Ml3D232.