Molecular Marker Screening For The New Powdery Mildew Resistance Gene In Lankao906

Wheat Lankao906 lines are new powdery mildew resistance germplasms selected in Henan province. Genetic analysis showed that Lankao906 carry a recessive powdery mildew resistance gene temporarily named PmLK906. To further study and use PmLK906, SSR technique and gene chip hybridization combined with bulked segregant analysis (BSA) was used to develop molecular markers linked to PmLK906. PmLK906 was located in chromosome 2AL by Chinese Spring nulli-tetrasomic and 2AL-deletion lines. The results can be directly used in molecular marker assistant selection, and provide a base for map based cloning of PmLK906. The detail studies are listed below:1. Crosses of powdery mildew resistant and susceptible wheat lines were made between Chinese Spring, Yumai21,20086 and Lankao906. Seedling powdery mildew assessments of the F₁, F₂ and F_2:3 lines were carried out by detached leaf culture method. The results showed that Lankao906 carry a recessive powdery mildew resistance gene.2. The powdery mildew resistant and susceptible DNA bulks were constructed by BSA with the F_2:3 families of the cross Chinese Spring / Lankao906. Total 150 pairs of SSR primers were screened, and 2 pairs primers gwm265 and gdm93 showed stable polymorphisms between the two parents and the contrasting DNA bulks.3. Linkage analysis was carried out in a segregation population including 129 F_2:3 lines of the cross of Chinese Spring / Lankao906. The result showed that the products of gwm265 and gdm93 were linked to PmLK906 with genetic distances of 3.72 and 6.15 cM respectively. The two SSR markers were named Xgwm265 and Xgdm93.4. Xgwm265 was located in wheat chromosome 2AL by Chinese Spring nulli-tetrasomic and 2AL-deletion lines. Consequently PmLK906 was located in chromosome 2AL too.5. Powdery mildew resistant and susceptible cDNA bulks were constructed by BSA with the F_2:3 lines of the cross Chinese Spring / Lankao906. The Affymetrix? wheat genome array was hybridized using cDNAs from resistant and susceptible bulks as the probes. Several tens of ESTs related to PmLK906 were obtained. Later, a new wheat gene similar to csAtPR5 was isolated from Lankao906, and named TaAetPR5. 6. Linkage analysis in the segregation population of the cross of Chinese Spring / Lankao906 showed that TaAetPR5 linked to PmLK906 with a genetic distance of 7.62 cM. Linkage analysis in the segregation population of the cross of Chancellor / CI 14124 showed that TaAetPR5 linked to Pm4a with a genetic distance of 0 cM.