MlAB10: A Triticum turgidum Subsp. dicoccoides Derived Powdery Mildew Resistance Gene Identified in Common Wheat

Powdery mildew is an economically important disease in wheat (Triticum aestivum L.). NC97BGTAB10 contains powdery mildew resistance introgressed from wild emmer wheat (T. turgidum subsp. dicoccoides). The objectives of this research were to genetically characterize the powdery mildew resistance in NC97BGTAB10, identify SSR markers closely linked to the resistance gene, and provide evidence that the gene is novel. One hundred thirty nine F2:3 lines from the cross NC97BGTAB10/Saluda were evaluated in the field and greenhouse for reaction to powdery mildew. Resistance was controlled by a single gene. Bulked segregant analysis identified a polymorphism between the resistant and susceptible bulks on chromosome 2BL. The population was genotyped with SSR markers that were specific to chromosome 2B and a linkage map was developed. The SSR marker Xwmc445 mapped 7 cM proximal to the resistance gene and no marker could be mapped distal to the gene. It was concluded that the resistance gene lies in the distal tip of chromosome 2BL. The powdery mildew resistance genes Pm33 and MlZec1 have also been mapped to the region. A detached leaf test with two powdery mildew isolates indicated the resistance gene in NC97BGTAB10 was different from MlZec1. No allelism test could be conducted to determine the relationships between the resistance genes in NC97BGTAB10, Pm33 or MlZec1 at this time. Thus, the resistance gene in NC97BGTAB10 was given the temporary designation MlAB10.