A major rust resistance gene was identified in the cultivar R570. This gene was linked to an RFLP marker, revealed by the probe CDSR 29, left unliked in the available R570 map. We developed an RFLP strategy taking advantage of the synteny between sugarcane, sorghum, rice and maize to position the rust resistance gene on the R570 map and to build a fine map in the vicinity of the resistance gene. We first positioned the CDSR 29 probe on our sorghum map. Then, through comparative mapping, we identified homeologous segments in several grass species, and selected 252 potentially useful probes in the targeted region. One hundred and thirteen of the probes tested hybridized with sugarcane DNA and were analyzed on a set of 88 individuals of the R570 population. This enabled us to position the rust resistance gene as well as 44 new probes on linkage group VII. The resistance gene appeared at a terminal position of a cosegregation group belonging to this linkage group. These data enable us to examine precisely the syntenic relationships between the genome of sugarcane, sorghum, maize and rice in the targeted area. However, the closest RFLP marker remains CDSR29. A second approach has thus been developed using bulked segregant analysis (BSA) with AFLP. This enabled to identify 5 AFLP markers located on both sides of the rust resistance gene. (Texte intégral)