MAP-BASED CLONING APPROACH FOR ISOLATING THE RESTORER GENE Rf1 IN SUNFLOWER (Helianthus annuus L.)

¹ Institute of Crop Science and Plant Breeding, University of Giessen, 35390 Giessen, Germany

² Department of Biological Sciences, Clemson University, Clemson, SC 29631-1903,USA

In sunflower, commercial hybrid breeding is based on a single source of cytoplasmic male sterility, the PET1 cytoplasm. Fertility restoration of F1 hybrids requires dominant nuclear restorer gene(s). Using RFLP, RAPD, SSR and AFLP technique we try to isolate the restorer gene Rf1 by a map-based cloning approach. So far, 6 AFLP markers(2 linked in attraction and 4 in repulsion) as well as 3 RAPD markers (2 linked in attraction and 1 in repulsion) could be mapped to the Rf1 gene in a region covering less than 2 cM. Two of the RAPD markers were converted into STS-markers which can now be used for marker assisted selection. These markers were also tested in a set of 9 maintainer and 11 restorer lines to see if they are applicable in other cross combinations. An F2 population of 1,068 plants is now available for fine mapping of the restorer gene. In addition, RAPD, RFLP, SSR and AFLP markers have been used to build a sunflower map. A BAC library using the restorer inbred line RHA325 and the vector pBeloBAC11 is under preparation which will allow to construct a contig for this region.