Molecular Markers And Mapping Of A Major Resistance Gene To Stripe Rust (Puccinia Striiformis West.f.sp.tritici) In Chinese Native Wheat Variety Hongmai (Su 1661)

Wheat stripe rust, caused by Puccinia striiformis West. f. sp. tritici, is one of the most important wheat diseases in the world. Growing resistant cultivars is the most economic, effective and environment-friendly way to control the disease. At present, the simplication of stripe rust resistance genes in commercial wheat cultivars haven't changed yet though a lot of cultivars are used in wheat production. Most of the improved varieties were breeded with introduced resistant resources in China for many years. And there's very little study on the abundant Chinese native wheat varieties. Hongmai (Sul661), a Chinese native wheat variety, showed excellent seedling and adult resistance to the prevalent races such as CY32, CY31, CY29, CY26 and CY19 of P. striiformis West. f. sp. tritici from China.In this study, a set of different progenies derived from the cross between a susceptible variety Mingxianl69 and the Chinese native variety Hongmai (Sul661) were prepared. Genetic analysis of resistance was carried out by inoculating representative main races of Chinese wheat stripe rust in greenhouse. Chromosomal location of a major stripe rust resistance gene in Hongmai (Sul661) was carried out by using microsatellite markers combined with bulked segregant analysis. Molecular markers for the target gene were developed by using AFLP method. The main results gained are as follows:1. Resistance assessment and genetic analysis indicated that the resistance to the race CY32 in Hongmai was independently controlled by one dominant gene and one recessive gene; and the resistance to the race CY26 was controlled by one dominant gene, named as YrHm temporarily.2. Through polymorphic analysis of microsatellite markers between the resistant and susceptible DNA pools and genetic linkage analysis with the F₂ segregant population, 4 SSR markers on 6DS and YrHm gene were found on the same linkage group. The order of them was YrHm-Xgwm904-Xbarcl73-Xcfdl3-Xcfd42-centromere. A whole set of Chinese Spring nulli-tetrasomic lines were examined with the SSR markers Xgwm904,Xbarc173,Xcfd13 and Xcfd42. The results indicated that the 4 markers were all on the wheat chromosome 6D. Based on the analysis of SSR markers and nulli-tetrasomic lines, the resistance gene YrHm was located on the chromosome 6DS.3. A total number of 324 primer combinations were used in AFLP analysis. Two polymorphic DNA fragments amplified respectively by 2 primer combinations P20/M77 and P70/M77 were found linked to YrHm gene. Sequence analysis indicated that the 2 polymorphic DNA fragments were the same one. The polymorphic DNA fragment P70/M77₂₃₉ had been converted into SCAR marker SC-P70M77.4. Calculated by the software Mapmaker 3.0b, the genetic distances between the markers SC-P70M77, Xgwm904, Xbarc173, Xcfd13, Xcfd42 and YrHm gene were 7.3 cM, 7.1 cM, 26.2 cM, 48.7 cM and 63.1 cM respectively. The marker SC-P70M77 was on one side and the 4 SSR markers on the other side of YrHm gene. 5. Resistance of the varieties Fielder with Yr20, Lee with Yr23, Tres with YrTr1, and Tyee with YrTye, was assessed by inoculating with the race CY26. The results indicated that Fielder, Lee and Tyee were susceptible and Tres was resistant. Tres is a variety from North America, and derived from the cross of CI12666/6×'Omar'/3/T.spelta/'Coastal'/3×Omar. Hongmai is a native variety from Xiuwen, Guizhou, China. Therefor the gene YrHm in Hongmai may be a new resistance gene to stripe rust.