In a selfed progeny of the sugarcane cultivar R570, we found a 3:1 (resistant:susceptible) segregation for rust resistance which indicated the presence of a major dominant resistance gene. This gene was linked at approximately 10 cM to an RFLP marker revealed by the probe CDSR 29. Two different approaches have been applied to build a fine map in the vicinity of the resistance gene. The first was an RFLP strategy taking advantage of the synteny between grass species. We first positioned the CDSR 29 probe on our sorghum map. Then, through comparative genome mapping, we identified homeologous segments in rice, sorghum and maize, and selected 252 potentially useful probes in the targeted region. These heterologous probes were evaluated for their ability to cross-hybridize with sugarcane DNA. Useful probes were mapped on a subset of the R570 population. This enabled us to position the rust resistance gene at a terminal position of a cosegregation group belonging to linkage group VII, and also to add 44 probes to this linkage group. The second approach was to use bulked segregant analysis (BSA) with AFLP markers. Two pools of DNA were made, one from 5 resistant individuals and the other from 5 susceptible individuals, and screened by AFLP. Five markers that co-segregated with the rust resistance gene were identified. Analysis of their segregation on 300 individuals localized three of these markers on one side of the rust resistance gene at 2.6, 4.2 and 7.8 cM, and two at 4.0 and 9.2 cM on the opposite side. (Texte intégral)