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Why don't roses naturally come in blue?
Biology & EcologyStandardAbout 2 min
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You sometimes see blue roses in Valentine's bouquets, yet blue roses are almost absent in nature. Roses lack the genes needed to make blue pigment, and they also lack the helper compounds that make blue deeper. So where do blue roses actually come from?
Suntory in Japan began studying this question in 1990. They found that four genes from other blue flowers could let roses make both blue pigment and a helper compound called C-glycosides. The team introduced these four genes into roses, then grew them in Japanese greenhouses and Colombian fields to watch how flower colour changed.
The key point: flower colour is not decided by pigment alone. C-glycosides are colourless themselves, but when they interact with blue pigment, the blue becomes deeper and richer. In 2004, the team produced roses that accumulate blue pigment, with petals also containing C-glycosides, giving a violet-blue colour. Petals with more C-glycosides appeared bluer.
In Japanese greenhouses, these roses bloomed blue for seven years in a row; in Colombian fields, they kept this trait for three years. This shows the blue trait can persist across different environments after the genes are introduced, opening a new route toward bluer roses.
The link between C-glycosides levels and blue depth is so far an observed correlation, not proof that more always means bluer. And blooming blue for several years in greenhouses and fields does not mean every growing condition will give the same stable blue.
Flower colour is mainly set by pigments in the petals, but pigments are not the whole story. The same pigment can look different in depth under different conditions. Co-pigments are colourless compounds that interact with pigment molecules, making the colour deeper and more stable. Roses naturally lack the genes to make blue pigment and co-pigments, so they cannot bloom blue on their own.
The link between higher C-glycosides and bluer petals is an observed correlation, not proof that more always means bluer.
Co-pigments are completely colourless themselves, yet they can make blue pigment look bluer and deeper.
This article was researched and written from the following materials:
News report: Solidot28 September 2026Read the original
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