A preliminary study of directional introgression and improvement of resistance genes to powdery mildew in hybrid wheat.

To develop a combination of wheat hybrid system with high resistance to powdery mildew diseases,we used N9134,N95175 as sources for resistance to powdery mildew to improve the parents of the strong advantage of series of 'XIZA' hybrid varieties of wheat.Wheat powdery mildew fungus strains from different regions in shaanxi province were collected and used to inoculate the parents,F1 offspring and backcross offspring.Meanwhile,the SCAR markers co-separated with Pm21 gene and the SSR marker closely linked with PmAS846 gene were used to identification of resistance.The results showed that F1 hybrids derived from N95175,N9134 with Pm21 or PmAS846 were characterized with high resistance at seedling and adult plant period,and they possessed identical disease resistance as resistant parent,which accorded with the heterosis dominance hypothesis.Besides,plants showing disease-resistance did not produce molecular markers,which indicated an inaccuracy of molecular markers present sometimes.We established an improved hybrid wheat breeding system with high disease resistance,and therefore succeeded to maintain the original heterosis of wheat hybrids as well as other agronomic traits,which provided a novel avenue for super hybrid wheat breeding.