Sequence evidence for intergeneric DNA introgression from Haynaldia villosa 6VS chromosome into wheat near-isogenic lines resistant to powdery mildew

Introgressive hybridization has played a crucial role in crop breeding. Powdery mildew-resistant gene 21 (Pm21), located on the short arm of chromosome 6V of Haynaldia villosa (H. villosa), is typically a representative element which is transferred to hexaploid wheat through introgressive hybridization. Determination of sequence evidence for H. villosa DNA introgression would help trace Pm21 in breeding wheat that are resistant to powdery mildew. In this study, we generated a wheat near-isogenic line (NIL) that was resistant to Blumeria graminis f. sp. tritici (Bgt) by using the wheat cultivar, Jing411, as the recurrent parent and the wheat-H. villosa chromosome translocation line, T6VS.6AL, as the donor parent of the Bgt resistance gene. We inoculated Jing411, T6VS.6AL, NIL, and H. villosa with Bgt race15. A large number of valving appressoria, contorted germ tubes, and slender germ tubes were observed in the NIL. In the host cells, cytoplasm agglomeration, papillae, haloes and hypersensitive reactions were detected. These results indicated that the NIL inherited the resistance to Blumeria graminis from the T6VS.6AL. We screened Jing411, T6VS.6AL, NIL, and H. villosa by using the Amplified Fragment Length Polymorphism (AFLP) technique and identified 21 AFLP fragments on chromosome 6VS. Among them, EACG/M14-301 in the NIL showed 100% identity to the fragments in T6VS.6AL and H. villosa. This result indicated that EACG/M14-301 might be a sequence evidence for intergeneric DNA introgression from H. villosa into common wheat. Our work will contribute to future investigations into wheat resistance breeding.