Characterization of Durum–Einkorn Amphiploids for Introgression of Powdery Mildew Resistance from Einkorn into Common Wheat

The einkorn wheat group, comprising ancient diploid species (2n = 14, AA), including Triticum monococcum, Triticum boeoticum, and Triticum urartu, represents a valuable source of genetic variation for improving disease resistance in wheat. To develop a practical platform for introgressing powdery mildew resistance into bread wheat, we screened 21 einkorn accessions with Blumeria graminis f. sp. tritici (Bgt) race E09 and identified seven resistant donors. Because direct hybridization between diploid einkorn (AA) and hexaploid wheat (AABBDD) is constrained by genomic divergence and poor cross-compatibility, we crossed resistant einkorn accessions with susceptible durum wheat and induced chromosome doubling in the F1 hybrids to generate synthetic durum–einkorn amphiploids. Nine amphiploids were obtained. Chromosome counts and genomic in situ hybridization confirmed the expected genomic constitution (AABBAA) in most lines, with limited variation in chromosome number in two amphiploids. Phenotyping against Bgt race E09 showed that three amphiploids retained high resistance, four showed moderate resistance, and two were moderately susceptible. Marker analysis identified five einkorn accessions contain known Pm genes such as Pm60, Pm60b, and PmNCA6/Pm37, as well as their derived amphipliods. Two einkorn accessions and their derived amphiploids may harbor novel Pm genes. Field evaluation of the agronomic traits of these amphiploids indicated some improvement in tillering, spike length, and seed weight. Moreover, these amphiploids had better seed-setting rates in crosses and backcrosses with common wheat. These synthetic durum–einkorn amphiploids thus offer a new bridging platform for transferring alien genes from diploid einkorn to hexaploid common wheat, providing valuable genetic resources for wheat-breeding programs.