Magazine published 2016.

Hybridization with introduced genetic resources is commonly practiced in ornamental plant breeding to introgress
desired traits. The 19th century was a golden age for rose breeding in France. The objective here was to study the
evolution of rose genetic diversity over this period, which included the introduction of Asian genotypes into Europe.
A large sample of 1228 garden roses encompassing the conserved diversity cultivated during the 18th and 19th centuries
was genotyped with 32 microsatellite primer pairs. Its genetic diversity and structure were clarified. Wide diversity
structured in 16 genetic groups was observed. Genetic differentiation was detected between ancient European
and Asian accessions, and a temporal shift from a European to an Asian genetic background was observed in cultivated
European hybrids during the 19th century. Frequent crosses with Asian roses throughout the 19th century and/
or selection for Asiatic traits may have induced this shift. In addition, the consistency of the results with respect to
a horticultural classification is discussed. Some horticultural groups, defined according to phenotype and/or knowledge
of their pedigree, seem to be genetically more consistent than others, highlighting the difficulty of classifying
cultivated plants. Therefore, the horticultural classification is probably more appropriate for commercial purposes
rather than genetic relatedness, especially to define preservation and breeding strategies.