Genetics and genomics of prickle in roses

Rose is the most important ornamental plant in the world and an interesting model to study the genetic basis of original ornamental traits such as scent production, seasonality of blooming or the presence of prickles. Our objective is to decipher the molecular control of ornamental traits in rose by combining genetic and genomic approaches. I will present here the last results we obtained concerning prickle development. In rose, two types of prickles are present: non-glandular (NGP) and glandular (GP) prickles. Prickles (NGP or GP) are originated from cells below the protoderm clearly demonstrating that they correspond to prickles and not trichomes. Four QTLs controlling the presence and density of prickles were identified. By comparing the transcriptome of glabrous and prickle shoots, we identified key regulators and interestingly demonstrated that homologous genes, which known to be involved in trichome initiation and development, were not involved in prickle initiation and development. These results suggest a unique developmental pathway for prickles in rose. All these results contribute i) to well understand the genetic determinism of ornamental traits, ii) to develop tools to help breeding, and iii) to eventually better understand the rose domestication.