Stripe Rust And Drought Resistance Of Derivatives Of Wheat And Genetic Research Of Stripe Rust Resistanct Wheat Line "Nannong790"

Stripe rust, caused by the Puccinia striiformis, is one of fungal diseases, which causes the serious damage of wheat production. China is the most serious pandemic area of the disease, causing 4 million hm2 heavy losses. The use of resistant cultivars is the most economical, effective, and environment friendly way to reduce damage and loss caused by stripe rust. However, with the races of the stripe rust pathogen have high variability and plant the single disease resistant cultivars in the same areas for many years may boost the pathogen directional selection, the resistant cultivars are likely to be susceptible to novel races of the stripe rust pathogen. Therefore, continuing to explore and create new resistance resources, and increasing the diversity of wheat resistance sources have the guided significance to breeding strategy. Distant hybrids from Triticum aestivum L. and wild relatives were thought rich resistance to plant disease and environment tolerance. To screen resistant materials to stripe rust and drought,the distant hybrid derivatives were screened for resistance to stripe rust and drought. Nannong790 was resistant to both stripe rust and powdery mildew, so it is an excellent resistant source. To characterize its resistance to stripe rust and its genetic rules, this project constructed genetic segregated populations from the hybrid of the resistant accession Nannong790 and the susceptible cultivar Avocets, and study stripe rust resistance, and analyze genetic rules. At the same time, combing with SSR markers, the resistant gene was firstly mapped. The purpose is to lay a foundation for marker-assistance-selection(MAS) breeding selection and disease-resistant breeding.Distant hybrids from Triticum aestivum L. and wild relatives were considered having abundant supply of desirable resistance. This study was conducted to select resistant source which was resistant to wheat stripe rust. During 2006 – 2012, the distant hybrid Derivatives from wheat and wild relatives were investigated for resistance to stripe rust in the field in Yangling of Shaanxi and Tianshui of Gansu, respectively. And the comprehensive agronomic characters of plants were evaluated as well. To further study the resistance to stripe rust, the selected distant hybrid derivatives were indentified for adult-plant resistance to stripe rust in both artificial nursery with multiple races at Yangling and natural nursery at Tianshui in late May or in early June of 2014. The selected materials were evaluated resistance to stripe rust at seedling stage with 3 races of Puccinia Triticina including CYR32 、 CYR33 and virulent-Yr26 pathotype(V26), combining with the detection of the known DNA markers WE173 and WE33 which were both linked to rust resistance gene Yr26. 106 derivative materials were firstly screened with stripe rust resistance and ideal agronomic traits; 79 materials were considered adult-plant resistance to stripe rust in Yangling and Tianshui, and the severity was between 5%-10%; Through the 3 races were inoculated and identified, 4 materials( WHD-1-8 、 WHD-13-3-3 、 WHD-15-3-4 、 WHD-16-1-7) with all-stage resistance(ASR) in all races test, 32 materials like WHD-1-3-1、 WHD1-4-2、 WHD-1-1-1, were considered adult-plant resistance(APR).Through molecular test, these materials did not contain the resistance gene Yr26. To assess the capability of drought stress, the selected resistant materials were treated with 15%(W/V) PEG-6000 solution, which was used to simulate drought stress experiment. The control plants were grown in Hoagland solution without PEG-6000 solution under the same conditions. Leaf Relative Water Content(RWC)、Relative Conductivity(RC)、Plant Height(PH)、Maximum Root Length(MRL) and Root-Shoot Ratio(RSR) were measured. In addition, the drought tolerance coefficients(DC) of 5 seedling traits were calculated and analyzed. The membership function values of drought tolerance(MFVD) of 5 traits were used as a comprehensive index for evaluation and selection of these materials drought tolerance. Based on drought stress and non-drought stress treats, combining with the drought resistance coefficient, 2 traits(PH and RWC) performed decreased trend, however 3 traits(MRL、RSR and RC) had uptrend. According to drought tolerance grades, out of 36 disease resistance materials, 6 materials displayed highly drought-tolerance, 18 materials had mild drought-tolerance and 12 materials were susceptible to drought stress. 24 novel resistant sources from the distant hybrid derivatives were screened out, which were resistant to stripe rust and drought stress, therefore these could be applied to wheat breeding program in Northwest regions of China.Nannong790 was derived from the cross between Wuzhuamai and Yangmai158, and has high adult resistance to epidemic stripe rusts in mixed nursery of Yangling. To identify inherent characterization and map the gene for resistance to stripe rusts, 5 Chinese isolates of stripe rusts(CYR23、CYR29、CYR31、CYR32、CYR33)were used to evaluated to the resistant spectral at seedling stage. The mixed races(CYR32 and CYR33) were selected to test Nannong790, Avocet S, F2 generations and F2:3 families from Nannong790 crossed with Avocet S. The results showed Nannong790 displayed middle-susceptible to yellow rusts CYR32 and CYR33 in China when tested with five races at seedling stage(IT≥6), however it displayed nearly immune in artificial nursery with mixed races at Yangling(IT≤2,S≤5%). It indicates that Nannong790 was adult-resistance.Through identifications of different generations, the resistance in Nannong790 was controlled by a single dominant gene, designated as Yr Nan temporarily. Segregated F2 progenies of the cross were used for bulked segregation analysis(BSA), SSR technology was used to map the gene. Six microsatellite markers(Xgwm11、Xbarc187、Xbarc181、Xgwm273、Xwmc419 and Xwmc216) were linked to Yr Nan and all of them have been mapped on chromosome 1BL, and the nearest markers and the heredity distance were Xbarc181(1.3c M) and Xgwm273(6.3c M). It would facilitate the marker-assisted-selection(MAS) and the applying of Yr Nan in wheat breeding programs.