Molecular mapping of the rf1 gene for pollen fertility restoration in sorghum (Sorghum bicolor L.)

We report the molecular mapping of a gene for pollen fertility in Al (milo) type cytoplasm of sorghum using AFLP and SSR marker analysis. DNA from an F-2 population comprised of 83 individuals was screened with AFLP genetic m arkers to detect polymorphic DNAs linked to fertility restoration. Fifteen AFLP markers were linked to fertility restoration from the initial screenin g with 49 unique AFLP primer combinations (+3/+3 selective bases). As many of these AFLP markers had been previously mapped to a high-density genetic map of sorghum, the,target gene (rf1) could be mapped to linkage group H. C onfirmation of the map location of rf1 was obtained by demonstrating that a dditional linkage group-H markers (SSR, STS, AFLP) were linked to fertility restoration. The closest marker, AFLP Xtsa2582, mapped within 2.4 cM of th e target loci while two SSRs, Xtxp18 and Xtxp250, flanked the rf1 locus at 12 cM and 10.8 cM, respectively. The availability of molecular markers will facilitate the selection of pollen fertility restoration in sorghum inbred -line development and provide the foundation for map-based gene isolation.