Development and identification of a wheat-rye breeding line for harmonious improvement between powdery mildew resistance and high yield potential

Powdery mildew, caused by Blumeria graminis f. sp. tritici (Bgt), is a devastating disease that seriously threatens the wheat yield and quality. To control this disease, host resistance is the preferred measure. However, wheat breeding is a complex process with elusive exchange and recombination of the traits from their parents. Increased resistance often leads to a decline in other key traits, such as yield and quality. Developing breakthrough germplasms with harmonious powdery mildew resistance and other key breeding traits is attractive in wheat breeding. In this study, we developed an ideal wheat breeding line AL46 that pyramided its hexaploid triticale parent-derived desirable yield traits and its wheat parent-derived powdery mildew resistance gene Pm2. Sequential genomic in situ hybridization (GISH), multicolor GISH (mc-GISH), multicolor fluorescence in situ hybridization (mc-FISH), and molecular marker analyses revealed that AL46 was a wheat-rye T1RS·1BL translocation line. Genetic analysis combined with function marker detection and sequence alignment were used to confirm that AL46 carried the Pm2 gene. Then, we evaluated the powdery mildew resistance and comprehensive traits of AL46, and just as we designed, AL46 showed harmonious powdery mildew resistance and some key breeding traits. This study not only developed an ideal wheat germplasm resource, but also provided a successful example for pyramiding breeding, which could be a promising direction for wheat improvement in the future.