Dogroses are allopolyploids with mostly odd somatic chromosome sets (5x) which are maintained by the fusion of monoploid sperm and tetraploid egg cells. During the unique canina-meiosis two chromosome sets form bivalents, while the remaining univalents were exclusively transmitted by the egg cell. It is supposed that dogrose species hybridise frequently among each other, however, genetic data were anecdotal so far. In this thesis, the frequency of hybrid formation between the subsection Caninae and Rubigineae as well as the genomic and transcriptomic consequences of these hybridisation events were investigated. Based on microsatellites it could be demonstrated that hybrids between both subsections originated spontaneously in natural populations. However, hybrid establishment was biased towards the involvement of non-reduced egg cells of subsect. Rubigineae. These hybrids could morphologically differentiated to some extent by multivariate analyses. The composition, inheritance and expression of ribosomal RNA genes (rDNA) in the subsections and their hybrids were studied with high-throughput sequencing and fluorescence in-situ hybridisation (FISH). Rosa canina (Caninae) contained predominantly Canina ribotypes, and co-localised 18S/5S rDNA loci occurred on bivalents; the rDNA of R. inodora (Rubigineae) was dominated by the Rubiginosa-type and co-localised 18S/5S rDNA loci occurred on univalents. These differences in rDNA composition support the hypothesis of polyphyletic formation of the subsections and thus of the canina-meiosis. The loci were additively inherited to the hybrids, however, the Canina type was dominantly expressed. The methylation and expression patterns were also mostly additively inherited to the hybrids, but organ-specific differences were detected.