Carnations (Dianthus caryophyllus) do not naturally produce a blue color. This absence is due to a specific genetic limitation within the plant’s biological machinery. Modern science achieves this hue through two distinct methods: temporary dyeing of cut flowers or permanent genetic modification.
The Science Behind the Missing Blue
Carnation color is determined by anthocyanin pigments, which are flavonoids responsible for red, purple, and blue hues. Carnations naturally create red and purple anthocyanins, such as pelargonidin and cyanidin. They cannot proceed to the final blue stage because they lack the ability to synthesize delphinidin, the pigment required for a true blue or violet shade.
The carnation genome lacks an active gene for the enzyme flavonoid 3′,5′-hydroxylase (F3’5’H). This enzyme adds two hydroxyl groups to the anthocyanin precursor, a required step to synthesize delphinidin. Without F3’5’H, the production process stops short of the blue pigment. This genetic barrier cannot be overcome using traditional cross-breeding techniques.
The Artificial Blue: Dyed Carnations
The most common way people encounter “blue” carnations is through dyeing, a simple post-harvest method. This process relies on the flower’s natural vascular system to draw colored water into the petals. White or light-colored carnations are harvested and their stems are placed into a solution of concentrated floral dye.
The cut stem absorbs the dye solution through the xylem, transporting the colored water into the petals. The dye molecules are then deposited in the flower tissue. The resulting color is often not a pure blue but can appear as a teal, greenish-blue, or streaky color, depending on the dye concentration. This temporary, artificial color is widely used in the floral industry for novelty purposes.
The Engineered Blue: Biotechnology Solutions
A permanent and sophisticated method for achieving a blue-like color involves modern biotechnology and genetic engineering. In the 1990s, scientists created the world’s first genetically modified carnations, such as the commercially available ‘Moondust’ variety. This was accomplished by bypassing the plant’s natural genetic limitation.
The process involved isolating the F3’5’H gene from a donor plant, such as a petunia or pansy, which naturally produces delphinidin. This specific gene was then inserted into the genome of a white carnation variety. This new genetic information enabled the carnation to produce the missing flavonoid 3′,5′-hydroxylase enzyme.
The transgenic carnations now accumulate delphinidin, shifting the color toward the blue end of the spectrum. The resulting flowers appear in shades of mauve, lavender, or violet, rather than a deep, true blue. This color is a permanent, heritable trait, meaning the plants can grow and produce blue-hued flowers without artificial dyeing.
The ‘Moondust’ carnation was first commercialized in 1997 as one of the first genetically engineered ornamental crops sold globally. The presence of delphinidin alone is not always enough to achieve a pure blue. The final shade is also influenced by the flower’s vacuolar pH and the presence of co-pigments.