| Sharp eyespot is a fungal disease caused by Rhizoctonia cerealis or Rhizoctionia solani. With the increase of irrigation and fertilization application, changes in agronomic practices and global warming up climate, sharp eyespot has become one of the most important diseases affecting wheat production in China. Deployment of resistance varieties is the most effective and economical strategy to control the disease. However, most of the commercial varieties and core collection for wheat breeding were identified to be highly susceptible to sharp eyespot, and this resulted in more frequent epidemic and increase of endanger acreage in recent years. The identification and utilization of new genetic resources with high sharp eyespot resistance will lay solid foundation for the development of new varieties with sharp eyespot resistance.ARz, a germplasm derived from wheat-rye translocation, showed stable resistance in identification in several years. To understand the genetics mechanism and identify the resistance loci of ARz, a genetic map was constructed using a recombinant inbred lines (RIL) population (F9) derived from the cross between ARz and a susceptible variety Yangmai158. The 137 RILs and their parents were inoculated with a high-virulent strain of sharp eyespot fungi R-46 using cultured toothpick and soil methods, respectively. The population showed normal distribution of disease index, with a disease index of 30.5-79.6% in cultured toothpick method and 25.5-71.2% in soil method, indicating the sharp eyespot resistance of ARz is a quantitative trait.Two hundred and seventy-six SSR markers were surveyed for polymorphism between the parents, and 97 loci were polymorphic in the population. By using marker regression analysis, 22 SSR markers associated with resistant QTL, expMning 2.7%-13.5% of phenotypic variance, were found based on the disease index data. Among them, Xgwm372, Xgdm93, Xgwm456, Xgwm341, Xgwm52, Xgwm645, Xgwm383, Xwmc42, Xbarc126, Xgwm149 and Xgwm194 were detectable in both inoculating methods. QTL mapping of sharp eyespot resistance was conducted using a software of MapMaker/Exp3.0, and 11 linkage groups were established. The total length of the linkage map was 1058.4 cM. The average interval is 14.7 cM and the shortest one is close to zero. Nine chromosome regions were detected for their association with the resistance through composite interval mapping (CIM, Windows QTL Cartographer). Seven of them were identified using both inoculating methods, among which QTLs mapped in the intervals of Xgwm608～Xgwm296 on chromsome 2D,of Xgwm296～Xgwm382 on chromsome 2D, of Xbarc77～Xwmc326-2 on chromsome 3B, of Xgwm341～Xbarc6 on chromsome 3D, of Xgwm415～Xgwm126 on chromsome 5A, of Xgwm400～Xgwm537 on chromsome 7B and of Xgwm44～Xgdm67 on chromsome 7D. The source of the resistance alleles were all from the resistance parent ARz, which explained 7.55%-20.78% of the phenotypic variance.The molecular markers associated with the QTLs for sharp eyespot resistance would facilitate the use of resistant genes of ARz, and the genetic information would be very important for better understanding the mechanism of sharp eyespot resistance in wheat.
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