Lines with resistance to powdery mildew in adult plant stage have been selected from two groups of F1 seeds produced by crossing T. aestivum with Aegilops variabilis (2n=28, UUSS). Two lines were derived from nonirradiated F1 seeds and another five lines originated from irradiated hybrid seeds.  Rusalka and Pliska bread wheat varieties were used as backcrossing parents. Two lines selected from the irradiated group, showed different resistance pattern in comparison to 18 wheat cultivars/lines possessing known powdery mildew resistance genes. Line 11-8 was previously identified with C-banding as a 1U(1B) substitution. It expressed a distinctive disease pattern, different from the parents and differential set of lines. It is suggested that the alien 1U chromosome is a carrier of resistance to powdery mildew, as evidenced by the disease pattern of doubled haploid lines derived from cv. Charodeika x line 11-8 cross. The DH lines expressed resistance to 8 from 11 isolates used. Additionally, the lines obtained from the original cross were subjected to a test for leaf rust resistance and compared to 11 cultivars possessing documented leaf rust resistance genes. At least four lines were postulated to carry unidentified genes that could not be resolved by the leaf rust isolates used.