S05 - Session O5 - Genetics and genomics of interest ornamental traits in rose

Authors: Laurence Hibrand-Saint Oyant, Ning-NIng Zhou, Julien Jeauffre, Annie Chastellier, Tatiana Thouroude, Vanessa Soufflet-Freslon, Thomas Debener, Marcus Linde, Fabrice Foucher *

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 flowering (recurrent blooming and double flower) and prickle development. We characterized the major gene responsible for the conversion of a simple flower with five petals into a double flower. The double flower phenotype is due to a dominant mutation of the AP2/TOE transcription factor. We also characterized QTLs responsible for the number of petals within double flowers. For the recurrent blooming locus, we identified new alleles for RoKSN , the gene previously identified to control continuous flowering. A null allele, leading to continuous flowering in Rosa chinensis 'Old Blush', was characterized with a deletion in the RoKSN gene, due to a large genomic reorganization. Another allele, responsible for a weak capacity to rebloom, was also detected and associated with a low RoKSN transcript accumulation. Concerning prickles, roses present two types of prickles: non-glandular (NGP) and glandular (GP) prickles. We demonstrated that NGP are originated from cells below the protoderms, 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 an 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.