Today we are featuring a very unusual taxon–one that you may have seen recently at the grocery check-out line, but have probably never seen growing: a genetically-engineered carnation by Florigene® known as ‘Moondust’.
Dianthus caryophyllus, the wild progenitor of many (all?) cut flower carnations, produces a pink flower. Careful breeding has yielded cultivated varieties of bright white, red, yellow and even green carnations. These colours, although not exhibited in wild, represent part of the natural carnation palette, which is dictated by two pigment types: the carotenoids and the flavonoids. The carotenoids provide yellow and orange pigments. The flavonoids are water-soluble pigments, and they can be broken down into three types: the cyanidins that yield red and magenta carnations, the pelargonidins that give us orange, pink, and red carnations, and the delphinidins, which, in theory, would produce blue or purple carnations, if carnations had any.
Since carnations lack delphinidins, no amount of traditional breeding will result in purple or blue varieties. The floral trade has overcome this limitation by simply immersing freshly-cut carnation stems in tubs of blue dye. White carnations are easily dyed, and dying carnations is a great science experiment to teach about capillary action. Roses also lack delphinidins, and are occasionally dyed blue in the same way.
Recently, geneticists have accomplished what breeders could not; the flower company Florigene® has genetically-engineered a series of purple carnations by implanting a carnation with a delphinidin-containing petunia gene. Florigene’s ‘Moondust’ carnation was introduced to limited commercial markets in 1996, becoming the first genetically-modified flower to be available commercially. These purple carnations do not carry the magnitude of health and environmental concerns as many other genetically-engineered crops do: they are not consumed, rarely produce seed, and do not re-grow vegetatively, so the risk of the plant or the genes spreading beyond human control is considered by many regulatory agencies to be small. This has helped make it possible for Florigene to introduce its blue flowers without much public debate.
Georg Tremmel and Shiho Fukuhara think ‘Moondust’ carnations should become part of the public dialogue about transgenic plants. In a project titled “Common Flowers/White Out” (also see Common Flowers/White Out project), Tremmel and Fukuhara experiment with turning a purple carnation back to white by genetically-modifying the Florigene flower to its original white-flowered form. This work was featured at the Ars Electronica Centre in 2013, but I have not been able to find out if Tremmel and Fukuhara were successful with their reverse-engineering.