The rose - where does this symbole of lovers come from?

The rose - where does this symbole of lovers come from?

The rose, a flower with a complex genome and symbol of lovers, dates back several million years and owes its existence to a series of genetic hazards!

A long flowering, a luxury of petals, a powerful perfume, thorns... Where does the rose come from, the flower of poets and lovers? It is a prodigy whose biologists have finally succeeded in deconstructing the genome, revealing the secret of its origins: a series of genetic coincidences.

For the ancient Greeks, the rose was born from the blood of Adonis and the tears that Aphrodite shed over her lover. For the Persians, it was the flower of "paradise", those first gardens of humanity filled with charm and wisdom.


The biologist Marie Fougère-Danezan is more precise: it is between Siberia and Alaska, on both sides of the current Bering Strait, that the rose has, for the first time, bloomed 60 million years ago - almost at the same time as the appearance of the first primates, and well before the eye of Sapiens has landed on it.

The researcher has reconstructed its evolutionary history after collecting the molecular profiles of a hundred wild specimens from the four corners of the world or preserved in old herbariums. But this new story is also a story... with a twist, which tells us how roses and strawberries once escaped from the same flower!

Originally, these two plants, which are now so radically different, blended into one common ancestor. Today, strawberry plants and roses still share almost the same number of genes, some of which are still arranged in the same way on whole sections of chromosomes. Except that the genome of today's rose is twice as large as that of the strawberry.


The difference? It is due to DNA sequences called "transposable elements", introduced during infections by viruses and causing random duplications within the genome over the generations. The rose would thus be, according to paleogenomics, the result of an infection... In a way, the first rose was a sick strawberry!

What did it look like then? It must have been quite similar to the current wild roses: a small thorny bush topped in spring by five-petalled flowers, whose color remains a mystery. Between white and pink, or a mixture of both, scientists hesitate. But it is unlikely that they were yellow as some wild species in Asia are.


During the next 30 million years, roses will mainly adorn the landscapes of the Far East and North America. Thanks to tectonic movements, they then crossed the great plains of Europe, colonized the Mediterranean shores, and even returned to North America, but this time by its western side. On the other hand, they stumbled on the equator, for reasons that remain unclear, such as their sensitivity to the environment.

More than half of the current wild species, out of the 200 known, come from Asia, and it is in this region that their fragrance has diversified. The crossbreeding between Europe and Asia has produced exceptional roses. Like the emblematic Damask rose, a must for perfumeries and distilleries, from the European rose Rosa gallica and Asian roses: Rosa moschata and Rosa fedtschenkoana.

Or like the mother of all modern roses, a hybrid created in 1867 by the Lyon rose grower Guillot and named La France. On closer inspection, this rose should rather be called La Chine. Its chromosome 3, which carries the genes involved in flowering, is almost entirely that of Rosa chinensis, the Chinese rose!

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