Researchers led by plant biologist Naonobu Noda at the National Agriculture
and Food Research Organization in Tsukuba, Japan have genetically engineered
the world's first true blue chrysanthemum.
True blue flowers are rare in nature, and occur only in selected species
such as morning glories and delphiniums. True blue requires complex
chemistry. Anthocyanins, the pigment molecules in the petals, stem, and
fruit, consist of rings that cause a flower to turn red, purple, or blue,
depending on what sugars or other groups of atoms are attached. Conditions
inside the plant cell also matter, so simply transplanting an anthocyanin
from a blue flower like a delphinium will not really work.
Noda first inserted a gene from the bluish flower Canterbury bell into a
chrysanthemum. The gene's protein modified the chrysanthemum's anthocyanin
to make the bloom appear purple instead of reddish. To get closer to a true
blue, Noda and his team then added a second gene from the blue-flowering
butterfly pea. This gene's protein adds a sugar molecule to the anthocyanin.
The research team planned to add a third gene, but the chrysanthemum flowers
were blue with just the two genes. Chemical analyses revealed that the blue
color was possible in just two steps because chrysanthemums already had a
colorless component that interacted with the modified anthocyanin to create
the blue color.