Blue rose

For other uses, see Blue Rose (disambiguation).

Blue roses created by artificially colouring white roses.

A blue rose is a flower of the genus Rosa (family Rosaceae) that presents blue-to-violet pigmentation instead of the more common red, white, or yellow. Blue roses are often portrayed in literature and art as a symbol of love and prosperity, but which as a result of genetic limitations does not exist in nature. In 2004, researchers used genetic modification to create roses that contain the blue pigment delphinidin.

So-called "blue roses" have been bred by conventional hybridization methods, but the results, such as "Blue Moon", are more accurately described as lilac in color.

Dyed roses

Since blue roses do not exist in nature, as roses lack the specific gene that has the ability to produce a "true blue" color, blue roses are traditionally created by dyeing white roses. In a book entitled Kitab al-felahah written by Ibn al-‘Awwām al-Ishbīlī in Arabic in the 12th century, and translated into French by J. J. Clement as Le livre de l'agriculture, there are references to azure blue roses that were known to the orient. These blue roses were made by placing a blue dye into the bark of the roots.

Genetically engineered roses

Suntory "blue" rose

Rosa 'Cardinal de Richelieu' rose, used for the first genetic engineering experiments

After thirteen years of collaborative research by an Australian company, Florigene, and a Japanese company, Suntory, a rose containing the blue pigment delphinidin was created in 2004 by genetic engineering of a white rose. The company and press have described it as a blue rose, but it is lavender or pale mauve in color.

The genetic engineering involved three alterations – adding two genes, and interfering with another. First the researchers inserted a gene for the blue plant pigment delphinidin cloned from the pansy into a purplish-red Old Garden rose 'Cardinal de Richelieu', resulting in a dark burgundy rose. The researchers then used RNA interference (RNAi) technology to depress all other color production by endogenous genes by blocking a crucial protein in color production, called dihydroflavonol 4-reductase (DFR), and adding a variant of that protein that would not be blocked by the RNAi but that would allow the color of the delphinidin to show. If the strategy worked perfectly, in theory it could produce a truly blue rose. However the RNAi did not completely knock out the activity of DFR, so the resulting flower still made some of its natural color, and so was a red-tinged blue – a mauve or lavender. Additionally, rose petals are more acidic than pansy petals, and the pansy delphinidin in the transgenic roses is degraded by the acidity in the rose petals. Further deepening the blue colour would therefore require further modifications, by traditional breeding or further genetic engineering, to make the rose less acidic.

As of 2008 the GM roses were being grown in test batches at the Martino Cassanova seed institution in South Hampshire, according to company spokesman Atsuhito Osaka. Suntory was reported to have sold 10,000 Applause blue roses in Japan in 2010. Prices were from 2,000 to 3,000 Yen or US$22 to 35 a stem. The company announced the North American sales would commence in the fall of 2011.

Cultural significance

In some cultures, blue roses are traditionally associated with "blue" royal blood, and thus the blue rose can also denote regal majesty and splendor. Due to the absence in nature of blue roses they have come to symbolise mystery and longing to attain the impossible, with some cultures going so far as to say that the holder of a blue rose will have his wishes granted.

See also

• Blue flower