Genetic Analysis And Molecular Mapping Of A Stripe Rust Resistance Gene Yrc25 In Wheat

Puccinia striformis f. sp. Tritici(PST),is an important worldwide wheat disease. Due to quick variations in small physiological seeds of stripe rust bacteria and the single source of anti-desease, disease-resistant seeds quickly lose their resistance after they are planted in large areas. A lot of experiments have showed that screening and cultivating the disease-resistant seeds is the most economic, safe and effective method of preventing wheat stripe rust disease. In order to achieve the diversity of stripe rust-resistant wheat genes diversity, this study has identified a hard-grain Cid25 artificially synthesized from wheat and rough goat grass (SORA/Aegilops squarrosa 207) and a small physiological seed CY32 with high resistance to stripe rust bacteria.The research results are summarized as follows:1.Using artificially-synthesized parents of wheat Cid25,F1 generations derived from the reaction of Cid25 with Mingxian169 (M169), M169XCid25 F2 generation groups, and F3 iosolated disease-resistant and disease-susceptible family groups, disease-resistant genetic analysis was conducted. The obtained results showed that the disease resistance of the artificially synthesized wheat Cid25 originated from its father As (207); all Cid25XM169 F1 single plants were resistant to a small physiological seed CY32 of stripe rust bacteria; but the separation of resistance from susceptibility cccured to the single plant of the M169×Cid25 hybrid F2 group,204 plants being disease-resistant and 80 being disease-susceptible among 284 plants of F2 generations. The chi-square test showed that this agrees with the separation ratio of 3:1,reaching a significant level and exhibiting a phenotype monogenic genetic separation law, This showed that the stripe rust resistance of Cid25 is controlled by a single dominant gene, Therefore, this stripe rust-resistant gene is named as YrC25 temporary.2. Using the BSA method, SSR primers, and M169×Cid25 F2 groups calibrated by F3 family, SSR molecular markers closely linked to YrC25 were screened. The obtained results indicated that the SSR markers, Xwmc419, Xwmc694, Xwmc156, Xbarc240, Xcfd65, Xbarc187, Xbarc137, Xgwm11,Xgwm18, and etc. located in the 1B chromosome are linked to YrC25. At the meantime, a furhter analysis with the Chinese Spring nullisomic-tetrasomics and ditelosomic lines of homoeologous group 1 suggested that YrC25 is located in the short arm of wheat chromosome 1B (1BS), and then a molecular marker linkage map of the disease-resistant gene was drawed. 3.Using the screened SSR molecular markers, the SSR marker Xgwm273 closely linked to YrC142, and the STS marker of Yr26, stripe rust-resistant genes, Yr24, Yr26, Yr10, Yr15, and etc, located in IBS chromosome, were differentiated. It was found that there were bands in YrC25 that are different from other known bands of stripe rust-resistant genes.This research result showed that the stripe rust resistance of the artificially synthesized wheat Cid25 was' by a phenotype nuclear gene, probably a new gene different from known stripe rust-resistant genes. This new gene was named as YrC25 temporary. It was located in the wheat IBS chromosome and closely linked to the SSR markers, Xwmc419, Xwmc694, Xwmc156, Xbarc240, Xcfd65, Xbarc187,Xbarc137,Xgwm11,Xgwm18, and etc. located in the IBS chromosome. This research offers new disease-resistant gene and highly effective method of molecular tagging for wheat stripe rust-resistant breeding.