Development and characterization of a novel compensating wheat-Dasypyrum villosum interstitial translocation line Dv6-IT1 carrying the powdery mildew resistance gene PmV

Abstract The powdery mildew resistance gene PmV, derived from the diploid Dasypyrum villosum accession No.1026, was previously introgressed into common wheat via the T6V#4S·6DL translocation. However, severely reduced transmission rates limited its breeding utility. To address this limitation, a recombinant translocation line T6VS#4S-6V#2S·6AL with improved transmission was previously created, then two smaller segmental translocations—Dv6T25 (T6VS-6AS·6AL, harboring 6VS 0–85 Mb) and Dv6T31 (T6AS-6VS·6AL, harboring 6VS 70 Mb–centromere), both carrying PmV—were generated using the ph1b induction system. In this study, homologous recombination within the overlapping region of Dv6T25 and Dv6T31 was exploited. A novel interstitial translocation line, Dv6-IT1, carrying an introgressed fragment of approximately 15 Mb, was identified. Molecular cytogenetic analysis confirmed that Dv6-IT1 is a compensating interstitial translocation with the configuration T6AS-6VS-6AS·6AL. Genetic analyses demonstrated that PmV in Dv6-IT1 follows normal Mendelian inheritance through both female and male gametes across diverse genetic backgrounds. The development of this small-segment interstitial translocation line provides a promising resistance source with minimal linkage drag for wheat powdery mildew breeding. This study not only addresses the transmission barrier of the original T6V#4S·6DL translocation but also establishes a model strategy for precision introgression of wild species-derived resistance genes into common wheat, paving the way for more efficient and sustainable wheat improvement in the face of evolving pathogen threats.