Genetic and Molecular Analyses of Key Loci Involved in Self Incompatibility and Floral Scent in Roses

Results on our investigations on the genetics and molecular biology of two major characters, self-incompatibility and floral scent will be presented. In crosses between diploid R. multiflora hybrids, the pattern of inheritance of double flowers was often found to be dependent on the direction of the cross. Genetic experiments involving backcrosses of individual progeny to both parents indicated the segregation of self-incompatibility alleles as predicted for a gametophytic SIsystem. First data on the genetics and the molecular biology of the S-locus will be presented. The second characteristic, floral scent of roses is very complex due to the large number of secondary metabolites that are involved in rose scent. As this biochemical complexity is very difficult to analyse in tetraploid genomes, we used diploid populations to study the inheritance of individual scent components. Although levels of scent emission were not very high, we were able to characterise several QTLs contributing to the generation of 2-phenyl ethanol, geraniol, nerol, β- citronellol and their acetates. In addition, the position of structural genes for germacren D, alcohol acetyltransferase1, and various O-methyltransferases were mapped on the rose chromosome map. The generation of alcohol-acetates was studied in more detail genetically and on the molecular level.