Molecular Tagging Wheat Powdery Mildew Resistance Gene Pm21 And Molecular Marker-assisted Selection

In the present study, using wheat germplasm lines CB033, CB034 with gene Pm21 and the susceptible parents Huixianhong, Shannong 2618, we screened molecular markers closely linked with gene Pm21, and imported Pm21 into Shannong 2618 to improve its resistance to powdery mildew; we used transgenic wheat germplasm lines which contained the phosphorus efficient gene TaPHR1 to hybrid and backcross the currently promoting wheat varieties (Jimai 22, Taizhou 137 and Tainong 18) in Shandong province, and at the same time marker-assisted selection was conducted using markers linked with TaPHR1, in order to improve the phosphorus efficiency of the above wheat varieties. The main results obtained are as follows:(1) The preferred small groups (PSG) analysis was conducted using F2 segregating population crossing between CB033 and Huixianhong. Of the 258 SSR, EST-SSR and STS markers located on the wheat homoeologous group VI, 102 markers revealed polymorphism between the parents, 2 EST-SSR markers and 1 STS marker showed good consistency between the genotype and the phenotype to powdery mildew in PSG. Linkage relationship between Pm21 and molecular markers of Xcfe164, Xedm129 and Xcinau188 were established, with the corresponding distance of 3.18, 1.02 and 0.67 cM between Pm21 and the three markers, respectively. Authenticity verification of the linkage between Pm21 and the molecular markers were tested via F2:3 families and results showed that the three markers were reliable new markers linked to Pm21, which could facilitate molecular marker-assisted selection in breeding programs.(2) Backcrosses were executed between the wheat germplasm lines CB033 and CB034, both of which contained the powdery mildew resistance gene Pm21, and the line Shannong 2618 which has good agronomic characters but susceptible to powdery mildew, with Shannong 2618 as the recurrent parent, in order to improve resistance of Shannong 2618 to powdery mildew. In different backcross generations, the markers NAU/xibao15-902, XCAU127 and CINAU18-723 were used for marker-assisted selection of the gene Pm21 in their backcross progenies, through which we obtained improved lines of Shannong 2618, containing the resistance gene Pm21 and the good characteristics of both parents.(3) The transgenic wheat germplasm lines 19-6-5, 36-1-4, 38-6-5 and 38-6-7 which contained the phosphorus efficient gene TaPHR1 were utilized to hybrid and backcross the currently promotion wheat varieties Jimai 22, Tainong18 and Laizhou 137. In different generations, the marker BAR430 was used for marker-assisted selection of the gene TaPHR1, and improved plants or lines with pure alleles at the TaPHR1 locus and good characteristics from both parents were developed.(4) Using CB034, we firstly hybrided it with the agronomic parent Yannong 19 and Jimai 20, then with the patents 36-1-4, 19-6-5, etc. In the composite hybrids, we used markers NAU/xibao15-902 and BAR430 for marker-assisted selection of the powdery mildew resistance gene Pm21 and phosphorus efficient gene TaPHR1, and we got pure polymers containing both of the two genes.