Plant, Animal & Microbe Genomes X Conference

January 12-16, 2002
Town & Country Convention Center
San Diego, CA

Workshop: Compositae
            

NEW RESULTS ON REPRODUCTION IN SUNFLOWER AND MAPPING OF THE RESTORER GENE RF1

¹ Institut fuer Pflanzenbau und Pflanzenzuechtung I, IFZ, Heinrich-Buff-Ring 26-32, 35392 Giessen, Germany

² Institut de Biologie Moleculaire des Plant, 12 rue du General Zimmer, F-67084 Strasbourg Cedex, France

In sunflower, commercial hybrid breeding is based on a single CMS source, the PET1 cytoplasm. The restorer gene Rf1 restores pollen production in the presence of the CMS-inducing PET1 cytoplasm. Markers closely linked to the restorer gene have been identified and converted into STS markers. A BAC library consisting of 104,736 clones (twofold haploid genome coverage) was constructed using the restorer line RHA325 and pBeloBAC11. Screening of the BAC library with STS-markers detected clones which were used to build up a contig at the restorer locus. The growth of the pollen tubes towards the ovary is influenced by compounds present in the pollen and pistil, and by products synthesized through interactions between the pistil and the growing pollen tubes. The pistil- and pollen-expressed gene sf21 encoding a 352 amino acid polypeptide was isolated by differential screening of a floral cDNA library from sunflower and characterized. Screening of the sunflower BAC library allowed the identification of eight clones using sf21 as a probe. DNA fingerprinting and sequencing demonstrated that these clones represent six different loci. Three clones formed a contig for one locus. Gene structures of this gene family playing a role in reproduction were analysed. Promoter structures will be analysed to explain differential expression of the genes.