Photograph by Jonathan Kantor The mythic blue rose remains just beyond the grasp of genetic engineers—except as a photo illustration. |
The floor of the Silver Terrace Nursery in the San Francisco Flower Mart is crowded with buckets of long-stemmed roses. They come in more than 40 shades, a glorious sunset’s worth of reds, pinks, oranges, browns, yellows, and whites. And then, like a poke in the eye, there’s electric blue, the sort of color you’d see on a marching band uniform or a high school prom dress.
It’s a fake, of course—a white rose dipped in blue dye—but the nursery sells 75 a week. “They’re big for bar and bat mitzvahs,” says Silver Terrace’s owner, Robert Ruggeri. Not to mention graduations at the nearby University of California at Berkeley, whose colors are gold and blue.
Roses have been cultivated since before Christ in almost every size, shape, and color, yet breeders have never managed to create a blue rose. Sure, some varieties are marketed with names like ‘Blue Boy’ or ‘Blue Bell’, but as many a disappointed gardener can attest, the blossoms are invariably lavender or purple. A true blue bloom remains elusive and mythic—the Holy Grail of gardening.
“That’s just genetics,” says Randy Woodson, associate dean of agriculture at Purdue University in Indiana. Roses lack the gene that codes for blue pigment, he explains. Carnations, chrysanthemums, and gerberas are also blue-impaired, and other flowers have their own genetically limited palettes: There’s no such thing as a red iris, for instance, or a white marigold. Recently, however, biologists have begun to circumvent such limitations using the tools of biotechnology.
Plant geneticists are busy identifying dozens of stretches of DNA that help determine the size, shape, color, scent, flowering characteristics, and longevity of various plants. Yet floral bioengineering is barely out of the bud. Its efforts have focused on four areas so far: extending shelf life, developing new fragrances, restoring old ones (when’s the last time you could really smell a bouquet rose?), and breaking the color barrier. In 1986 an Australian company, now called Florigene (motto: “Smart flowers, better living”), decided to relaunch the ancient quest for a blue rose. Their original plan seemed simple: Take the blue gene out of petunias and transfer it to roses, as well as to carnations and gerberas. But it wasn’t that easy. Experiments had shown that the gene produced a class of enzymes called cytochrome P450, of which there turned out to be hundreds of different forms. To find the right one, research director Edwina Cornish and her colleagues painstakingly extracted one P450-producing gene fragment after another and transferred the most promising ones to petunias lacking the gene. It wasn’t until five years later, when Cornish was checking her latest batch of stubbornly white petunias, that a glint of colored pollen caught her eye. “It was a beautiful light iridescent blue,” she remembers.
 | Flowers usually begin to wilt when they produce a hormone called ethylene, which triggers the aging process. So biologists at the company Florigene have engineered carnations that switch off the ethylene gene. The blossoms stay bright and crisp about twice as long as conventional flowers. |
The company quickly patented the gene, confident that fields of blue roses were around the bend. “We were young and foolish,” Cornish says with a laugh. They soon learned that floral hues are products of more than pigment alone. A flower’s pigment resides within a watery cellular chamber known as a vacuole, and the environment of that vacuole differs from plant to plant. Its shape and acidity, the presence of metal ions or other pigments, and the arrangement of these various components—all affect the shade we see on a petal.