Résumé
A major resistance gene providing resistance to common rust caused by fungus Puccinia melanocephala has been identified in sugarcane cultivar R570 and is the focus of a mapbased cloning approach. Earlier work based on synteny among grasses and on Bulked Segregant Analysis with AFLP allowed to localize this gene at the extremity of one chromosome and to surround it with markers, the closest being located at 0.6 and 0.3 cM on each side. We are now exploiting the sorghum and rice physical maps, the rice genome sequence and the sugarcane ESTs to reach the gene. We have built a sorghum BAC contig covering the homeologous target area in sorghum and we are using the BAC-end clones as probes to saturate the target area with markers. We have identified the homeologous target area on the physical map of rice and the corresponding Rice BACs. Comparing the sequence of these rice BACs with the SUCEST data base, we identified sugarcane cDNAs that are being used to saturate the target area with markers. Some of these cDNAs may represent candidates for the target gene. (Texte intégral)