Background Powdery mildew caused by Blumeria graminis f. sp. tritici (Bgt) is prevalent in the main wheat-producing regions of China, resulting in severe yield losses in recent years. Mining and utilization of resistant genes from wild relatives of wheat is the most environmentally sound measure to control disease. Aegilops geniculata Roth (2n = 2x = 28, UgUgMgMg) is an essential and valuable disease-resistance gene donor for wheat improvement as a close relative species. Results In this study, to validate powdery mildew resistance locus on chromosome 7Mg, two genetic populations were constructed and through crossing wheat – Ae. geniculata 7Mg disomic addition line NA0973-5-4-1-2-9-1 and 7Mg (7 A) alien disomic substitution line W16998 with susceptible Yuanfeng175 (YF175, authorized varieties from Shaanxi province in 2005), respectively. Cytological examination, in situ hybridization (ISH), and functional molecular markers analysis revealed that the plants carrying chromosome 7Mg showed high resistance to powdery mildew in both F1 and F2 generation at the seedling stage. Besides, 84 specific markers were developed to identify the plants carrying chromosome 7Mg resistance based on the specific-locus amplified fragment sequencing (SLAF-seq) technique. Among them, four markers were selected randomly to check the reliability in F2 segregating populations derived from YF175/NA0973-5-4-1-2-9-1 and YF175/W16998. In summary, the above analysis confirmed that a dominant high powdery mildew resistance gene was located on chromosome 7Mg of Ae. geniculata. Conclusion The results provide a basis for mapping the powdery mildew resistance gene mapping on chromosome 7Mg and specific markers for their utilization in the future.

Background: Blumeria graminis f. sp. Tritici (Bgt) is prevalent in the main wheat-producing regions of China and result in serious yield losses in recent years. Breeding resistant cultivars is the most environmentally sound measure of disease control. Aegilops geniculata Roth, a close relative of common wheat, is an important and valuable disease resistance gene donor for wheat improvement.Results: In this study, to validate powdery mildew resistance on chromosome 7Mg, two genetic populations were constructed and analyzed. Wheat – Ae. geniculata 7Mg disomic addition line and 7Mg (7A) alien disomic substitution line crossed with susceptible Yuanfeng175 of susceptible powdery mildew respectively to form generations F1 and F2. Cytological examination, in situ hybridization (ISH), and functional molecular markers analysis showed that alien chromosomes could be inherited stably, produce different gamete types and enrich the intermediate materials for wheat genetic variation. The populations were inoculated with the physiological race E09 of powdery mildew at seedling stage. The results revealed that the plants showed high resistance to powdery mildew with chromosome 7Mg. Besides, more specific markers were developed to verify chromosome 7Mg resistance based on SLAF-seq technique. Then, 84 specific molecular markers were obtained about chromosome 7Mg. Among them, four markers were selected randomly to checked in two genetic populations. In summary, the above analysis confirmed that a dominant high powdery mildew resistance gene inherited were located on the chromosome 7Mg of Aegilops geniculate. Conclusions: The results provide a basis for resistance gene mapping and specific marker development in future.