Plant Palette

Plant Palette

Blue Roses

Photo of Jennifer Schultz Nelson

Jennifer Schultz Nelson
Extension Educator, Horticulture
jaschult@illinois.edu

In the world of flower breeding, the color blue is the "Holy Grail" of flower colors. Many spend their lives searching for this elusive flower color, but few find the real thing.

I've purchased many flowers labeled as "blue" only to be disappointed when they bloom and look purple to my eyes no matter how much I squint or otherwise try to convince myself they really are blue. So I was doubtful when my husband called my office one day to tell me about a Japanese company that had developed the first true blue rose. He thought it would be a good addition to our Illini orange and blue garden. He insisted it really was blue-- well, sort of.

The blue color of the blue rose is provided by the pigment delphinidin, named for being originally isolated from Delphinium. For the delphinidin in the flower to appear blue, the environment inside the plants' cells must be acidic.

This "acid factor" is what makes blue such a rare find in the plant kingdom. Not only does a plant have to have the gene to make delphinidin in its flower cells, the plant must be able to maintain a level of acidity within the cell to make the pigment appear blue. Few plants can accomplish this.

Roses do not naturally produce delphinidin. Though some estimates say there have been over 25,000 rose varieties bred, they are all some shade of red, white, pink or yellow. Blue roses created by traditional hybridizing techniques are all more a shade of lilac than really blue. Until recently the only way to obtain a true blue rose was to dye or paint a white rose.

Creating a blue rose required the use of genetic engineering. The Japanese company Suntory began its quest for the blue rose in a joint venture with Australian biotechnology company Florigene in 1990. Since roses do not naturally possess the gene for delphinidin, genetic engineers needed to transfer the gene from another plant that had the gene.

Their first attempts were to move the delphinidin gene from petunia. They were not successful at using this version of the gene in the rose, but they were able to move the delphinidin gene from petunia into carnation. By 1997, the first blue carnations, sold under the variety name 'Moondust', were available.

It wasn't until 2004 that Suntory unveiled the blue rose. Genetic engineers had finally found success using a delphinidin gene from pansy, along with genes from iris to produce the delphinidin pigment in roses. The resulting blue rose looks vaguely purple to most people-- a lot like the traditionally bred blue roses.

So were the 14 years of genetic engineering research a waste? Time will tell, but certainly the genetic engineers have set the stage for a true blue rose to be possible. The engineered roses not only have the delphinidin gene inserted in their genome, they have also been provided the genetic machinery to suppress the red pigments naturally present in roses.

Suppressing the red pigments in the engineered blue roses has not been perfect, that's why the new engineered roses appear faintly purple. Suntory's genetic engineers are continuing their research, striving to make the blue roses "clearer" by suppressing the red pigments entirely.

Besides a true blue rose, having blue pigment in the palette of rose colors will open up new possibilities in colors of new varieties.

Suntory plans to begin the marketing and sales of their blue rose in 2009. Considering the amount of time and money devoted to their development, I'm sure they will cost quite a bit. I have not seen it offered to homeowners yet, but when they are, I'm sure many gardeners will want to be the first on their block to grow a true blue rose.

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