When sex may or may not happen – The impact of asymmetrical meiosis on the evolutionary fate of genes in polyploid roses

Rosa represents an ecologically important genus with widespread hybridization and polyploidy. Moreover, the European dogroses are enigmatic in having a unique hemisexual reproduction: due to their asymmetrical meiosis (Canina meiosis) they combine features of both sexual and asexual reproduction in the same nucleus. Here we propose to explore Rosa genomes to investigate the origin of the Canina meiosis, its differential effects on chromosome and evolution mutational load compared to fully sexual rose species. Through comparative genomics we will trace the respective contributions of diploid roses to the genome of modern polyploids and determine allelic divergence of single copy genes in hemisexual and sexual species. In addition we will develop new cytogenetic markers to elucidate different phases of asymmetrical meiosis and their putative epigenetic control. Our aims will be tackled by the application of advanced computational methods allowing genome wide analyses of nuclear single copy genes using phylogenetic and population genetic approaches. Experiments will also involve Fluorescence-in-situ-Hybridization (FISH), chromatin immunoprecipitation and -histochemical labelling