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SémIDEEV à l’UMR

Génétique Quantitative et Évolution – Le Moulon

Ferme du Moulon – Salle de conférences

Vendredi 3 mars 2017

12h00

Fabrice FOUCHER

“Genetics and Diversity of Ornamental” team - UMR IRHS (Research Institute for Horticulture and Seeds)
Beaucouzé, Centre Inra d’Angers-Nantes

invité par Catherine Damerval
01 69 33 23 66 - Cette adresse email est protégée contre les robots des spammeurs, vous devez activer Javascript pour la voir.

" Blooming and perpetual blooming,
a long history!
"

Résumé

The rose (genus Rosa) is the largest economical plant in the ornamental sector for gardens, cutting flowers and flowerpots, with an important role in western and eastern cultures. This tremendous success can be explained by the ability of roses to flower continuously. Rose is a good model to study seasonality of blooming, a developmental process which is poorly understood. We have previously demonstrated that continuous flowering in rose is due to a mutation of a gene encoded a floral repressor, RoKSN, a TFL1 (TERMINAL FLOWER 1) homologue. In continuous-flowering roses, a transposon (with a copia element) is inserted into the gene leading to non-accumulation of the floral repressor and so to continuous flowering.

Our objectives were to understand the regulation, the mode of action of this floral repressor and its selection during the process of human breeding. We clearly demonstrated that RoKSN is a floral repressor in rose and in Arabidopsis. RoKSN is competing with a floral activator, RoFT, an homologue of FT, for the regulation of a transcription factor, leading to activation or repression of blooming. The seasonal flowering of rose can be explained by an endogenous (gibberellic acid) and environmental (vernalization) regulation of RoKSN.

In collaboration with historians, we studied the process of rose selection during the 18th and 19th centuries in France. By genotyping and sequencing RoKSN on a large collection of roses from this period, we showed a progressive selection of the copia allele (bringing continuous flowering). This copia allele is originated from China. Furthermore, we detected a new allele that can be responsible for intermediate phenotype (occasionally-reblooming). This new allele at the RoKSN locus encodes a functional RoKSN, with a weaker transcript accumulation.

These results open new way to finely control blooming in rose and more generally in perennial plants.