Identification And Molecular Mapping Of Stripe Rust Resistance In Synthetic Wheat

Stripe rust, caused by Puccinia striiformis f. sp. tritici （Pst）, is an air-borne fungaldiseases of wheat （Triticum aestivum L.） and it affects the production of wheat seriously. Dueto the high variability of Pst races, a new race would appeared in a relatively short period oftime. This always leaded to the resistance in the resistant material newly discovered graduallydegraded or even disappeared. It’s proved that the breeding of resistant varieties is one of themost economic, effective and environmental protection measures to prevent wheat stripe rustdisease. Screening new source material and resistance genes, exploiting the closely linkedmolecular markers for mrker-assisted selection and gene accumulation are the most importantmeans to prevent Pst races. In order to achieve the diversity of resistant genes diversity tostripe rust, a synthetic wheat line CI184（YAR/Aegilops tauschii493） was identified to showgood resistance to Chinese prevailing isolates of Pst, including CYR32, CYR33, CY-Su4,CY-Su5, CY-Su7, and V26. The research results are summarized as follows:1. Using the synthetic wheat line CI184, Mingxian169, F1, F2and F3populations derivedfrom the cross between CI184and Mingxian169to conduct genetic analysis. The resultshowed that all the F1individuals showed susceptible to the mixed races including CYR32,CYR33, CY-Su4, CY-Su5, CY-Su7, and V26. In the investigation of the infect type of114plants of the F2populations derived from Mingxian169×CI184showed36resistant and78susceptible. It showed that the resistance may be recessive.2. Using the synthetic wheat line CI175, Chuanmai28, F1, F2and F3populations derivedfrom the cross between CI175and Chuanmai28to conduct genetic analysis. The resultshowed that all the F1individuals showed resistance to CYR33. In the investigation of theinfect type of114plants of the F2populations derived from Chuanmai28and CI175showed286resistant and105susceptible, fitting3R:1S（χ2=0.717）. It showed that the resistance maybe one dominant gene.3. SSR markers showing consistent polymorphisms between the bulks and parents wereidentified by using the bulked segregating analysis （BSA） method. Six markers on wheatchromosome1B, including Xwmc694, Xgwm11, Xbarc187, Xgwm18, Xwmc626and Xwmc619,showed the consistent polymorphism between the bulks and parents. Then, these markerswere used to detect114F2:3lines to gain the genotype of the entire group. Based on the mean MDS and marker genotypes, the QTL, namely Qyr.zz₁B, was located between Xgwm18andXwmc626. Qyr.zz₁B explained13.36%phenotype variation in Sichuan and18.51%phenotype variation in Beijing.4. To distinguish the known Pst resistant genes located on chromosome1B, such as Yr15,Yr24and Yr26/YrCH42, three SSR markers closely linked to Qyr.zz₁B and one SSR markerclosely linked to Yr15were used to identified. It was found that the bands in Qyr.zz₁B weredifferent from other known bands of stripe rust resistant genes.5. For seedling tests, a total of31races of Pst, collected from China and differentcountries, were used to test responses of CI184, Yr15/6*AvS, Yr26/3*AvS, Chuanmai42,Mingxian169and AvocetS. At seedling-stage, CI184and Chuanmai42showed resistant to30Pst races and susceptible to Pst new race V26, while Mingxian169and AvS showedsusceptible to all the31Pst races. It is indicated that this material is resistant to stripe rust andmay be potentially applied in wheat resistance breeding to stripe rust. The test of mixed racesshowed that CI175showed resistance at all the stage.The result of this research showed that the stripe rust resistance of the synthetic wheatline CI184may be recessive, named as Qyr.zz₁B, probably a new gene different from theother known stripe rust resistant genes. It was located on the1B chromosome, closely linkedto Xwmc694, Xgwm11, Xbarc187, Xgwm18, Xwmc626and Xwmc619. The resistance of CI175may be controlled by one dominant gene. These materials may be potentially applied in wheatresistance breeding to stripe rust.