Monday, June 12, 2006

Blue Roses

First published in The Landscape Contractor magazine

“Is Blue the Color of Money?”

By Becke Davis

Blue roses. Black tulips. The difficulty -- even impossibility -- of producing particular flower colors has not stopped botanists and plant propagators from making the attempt. This century has seen many horticultural advances, from increased disease-resistance to improved cold hardiness, from pest-resistance to drought tolerance -- and that is only the beginning.

Flowers are being bred to bloom longer, bloom repeatedly, and even to shed their spent flowers. Hybridizers seek the ideal form, the most sublime foliage, the most artful flowers and the most memorable fragrances. The holy grail, though, the pot of gold at the end of the rainbow that always seems out of reach, is exactly that -- the colors of the rainbow that are the most elusive are considered by many to be the ultimate unreachable prize.

Blue is one of the least common colors in the garden, and therefore one of the most sought after. Growers and hybridizers are quick to jump on the bandwagon whenever a new cultivar exhibits the least bit of blue coloration. Polarizing lenses and digital adjustments enhance catalog illustrations but the real thing often disappoints. Many flowers -- from blue lilacs to blue hyacinths to ‘Johnson’s Blue’ cranesbill geraniums -- have enough blue to merit the name, but often with enough lilac, lavender, purple, pink or other tints to keep the color from being an out-and-out “true blue.”

The color blue, in itself, is not the real issue, though -- rarity is. You want a true blue? It’s hard to find a flower much bluer than ‘Heavenly Blue’ morning glory. That excellent hybrid is so commonplace, though, that packs of seeds can be bought for a dollar or two in the produce department of the grocery store. Yet if anyone was able to develop a strong yellow morning glory -- a color not found in the genetic material of the genus Ipomoea -- demand for this easy-to-grow annual vine would surely skyrocket. On the other hand, yellow roses are ten-a-penny. But blue roses? The search for a truly blue rose -- just like the search for a truly black tulip -- is legendary.

GM, genetic manipulation, has resulted in many improved plant hybrids and cultivars, so it is not surprising that early color breakthroughs were related to this relatively young science. In 1991 an Australian biotechnology company called Calgene Pacific (later Florigene) announced that they had succeeded in isolating the gene that causes blue pigmentation in flowers. It was anticipated that this breakthrough would quickly be followed by the introduction of blue flowers where there had never been blues before.

The original plan to remove blue genes from flowers such as petunias and simply add the gene to the genetic material of the rose proved to work better in theory than in reality. Research sponsored by the American Rose Society has shown that rose coloration is determined by a range of two pigments (quercetin and kaempferol) to five pigments (carotenoids, cyanidin, pelargonidin, quercetin and kaempferol), with no trace of the blue pigment delphinidin. (1) Adding the blue pigment to the genetic material of a rose did not result in a blue rose because, as it turned out, isolating the “blue gene” was only part of the problem.

The blue pigment, delphinidin, is apparently only able to transfer its blue qualities to flowers whose petals feature alkaline cellular matter. Even when the pigment was directly applied to rose petal cells, the acidic nature of the cellular material inhibited the blue pigment and kept the rose from changing color.

The search for the alchemist’s stone -- the magic that will enable scientists to manipulate the form, foliage, colors and other features of a plant at will -- continues. Blue roses made news in the current issue of Discover magazine not because of years of genetic engineering research, but because of a fluke that may produce a novel route to the development of a blue rose. A few years ago, scientists at the Vanderbilt University School of Medicine in Tennessee and the University of Queensland in Australia accidentally discovered a human liver enzyme was spontaneously converting an amino acid found in a bacterial source into an indigo dye. This serendipitous discovery has since led the team of scientists, whose primary focus is researching disease-fighting drugs, into a sideline of using the enzyme/bacteria method to produce pigments that may one day turn flowers green, purple, red or brown -- and, of course, true blue.

If a blue rose is ever developed, it may turn out to be more of a boon for the cut flower industry than for the landscape industry. Florists already dye or spray roses, carnations and other flowers to dress them up for St. Patrick’s Day, to match prom dresses and bridesmaid’s gowns. Would a rose that is naturally blue make that much difference? In the April 2004 issue of Discover magazine, Marten Chrispeels, a plant geneticist at the University of California at San Diego, pondered the value of such a rose: “ ‘Would you be willing to pay $4 for a blue rose? Maybe for one, but not for 12,’ ” he observed. (2)

James Will, a senior lecturer in Horticulture and Plant Breeding at Burnley College, University of Melbourne, Australia, estimates that “a blue rose would be able to capture 5% of the international cut flower market -- a prize worth many millions of dollars annually.” (3) However, he goes on to point out that 70% of cut flower rose production now takes place in Third World countries where developers of a blue rose may have trouble collecting royalties. Certainly, to some extent research in the field of genetically manipulated pigments is dollar-driven, but there are many who would brush off such mundane concerns, raising the search for color rarities to an almost mystical level.

While blue roses and black tulips are probably the most famous (as yet) non-existent plants, they are not by any means the only color rarities in the plant world. In addition to roses, flowers missing “blue genes” include carnations, chrysanthemums, lilies and gerbera daisies (all of which are top-selling cut flowers), and the search continues for black orchids, red irises and white marigolds. As with roses that are called “blue,” some hybrids claim to fill the gap with these colors, too. For example, there are marigolds sold as “white” but they are closer to cream or ivory.

Florigene may not have succeeded in producing a blue rose, but in 1996 they did introduce the world’s first commercially produced transgenic flower, a carnation called ‘Moondust’. Although this and subsequent introductions have greatly expanded the range of mauve and purple carnations, scientists at Florigene and elsewhere have still not succeeded in their goal of producing a carnation that is distinctly blue.

On the other hand, genetic manipulation is resulting in some surprising horticultural developments. While there continues to be a lot of unease about genetically manipulated crops, there has been less concern about the use of GM in horticultural areas. These “smart plant” studies include research into potatoes as vaccines, creating transgenic plants containing a fluorescent protein designed as drought “early warning” sign, putting the fragrance back into modern roses, creating flowers that bloom in summer and again in winter, developing cut flowers that won’t wilt for weeks, even plants that can help detect the presence of land mines (land mines release an underground gas that causes the normally green plant foliage to turn red).

Blue roses may one day be the pot of gold to the floral industry, and there is bound to be a trickle-down effect on the landscape industry. But the real effect won’t be seen until such genetic manipulation is so commonplace that clients will be able to build “do-it-yourself” plants on their computers, just by running down a checklist and clicking on the features of their choice. Will such genetic manipulation change the face of flowers forever? Will we still be able to say “A rose is a rose is a rose” or will we find ourselves describing colors as either “hydrocarbons and their oxygenated derivatives” or “polyphenolic compounds containing 15 carbon atoms”?

In the language of flowers, white roses mean purity and innocence, pink roses mean admiration and happiness, yellow roses mean friendship and delight and red roses are a universal symbol of love. Lavender roses mean love at first sight, deep pink roses mean “thank you” and coral roses represent desire. To researchers today, blue roses represent the possibility of wealth and the achievement of science over nature. If they achieve their goal, who knows what blue roses might represent to future generations?



(1) “1980 American Rose Annual Pigments and Petal Colors,” and “Inheritance of Pigments,” by Lidwien A.M. Dubois, Institute for Horticultural Plant Breeding, Wageningen, The Netherlands

(2) “The Biology of Flowers: Roses are Blue, Violets are Red,” by Susan Freinkel, Discover magazine, April 2004

(3) “Quest for the Blue Rose,” interview with James Will, senior lecturer in Horticulture and Plant Breeding at Burnley College, University of Melbourne, Australia at Global Garden

“Towards a Blue Carnation,” by Roger Fox, Hydroponics, Casper Publications, Mar/April 1997, copyright updated 2002,

“Biotech Beauty,” InfoSource, Issue 87, September 2003, Published by Ag-West Biotech, Inc., SABIC (Saskatchewan Agricultural Biotechnology Information Centre), Saskatoon, Saskatchewan, Canada

Press Release: “Planned release of transgenic rose (Rosa x hybrida) containing kanamycin or chlorsulfuron resistance gene and ‘blue’ gene (flavonoid 3’5’ hydroxylase), August 8, 1994, Dr. Stephen F. Chandler, Florigene Pty. Ltd., Collingwood, Victoria, Australia

“Brave New Rose,” by David Concar, October 31, 1998, New Scientist, England,

“Clever Carnations,” by Dr. Edwina Cornish, Managing Director, Florigene PTY. Ltd.,

“In Pursuit of Blue, Sweeter-Smelling Roses,” by Paul Elias, Associated Press, published in the Chicago Tribune on November 22, 2002

“What Rose Colors Mean,” by Dan Vierria, February 14, 2004, International Cut Flower Growers Association,

“Plants to Uncover Landmines,” by Laura Nelson, January 29, 2004, Aresa Biodetection/Nature News Service, Macmillan Magazines Ltd., 2004,

“What Flower is That?,” by Stirling Macoboy, Portland House, NY, 1988

“What Flower Glows in the Dark?,” by Chelsea Vandaveer, October 24, 2002, Weird Plants Newsletter,

“Evening Primrose,” by Mary Beth Zeitz, (ibid)

“Applications of Genetic Engineering in the Green Industry,” by Pablo Jourdan, Department of Horticulture and Crop Science, Ohio State University

“Biotechnology in the Garden,” by Claire Granger, Biologist, June 2001, Information Systems for Biotechnology newsletter