Finally, a true blue rose exists

This development could change poetry forever. Roses are red and now they’re also blue.

True blue roses were once thought impossible. Roses can make red and yellow pigments but don’t have an enzyme needed to make blue pigments. At least they didn’t until 2004, when researchers at the Suntory Global Innovation Center in Kyoto, Japan, genetically modified a rose to produce blue pigments. The team inserted the gene for an enzyme that can produce a blue pigment called delphinidin. But those roses were purplish, suggesting it takes more than blue pigment to make flowers blue.

Naturally blue flowers, such as irises, make blue pigments like delphinidin. But they also need almost colorless “co-pigment” molecules called flavone C-glycosides to create their blue hue. Those helper molecules stabilize pigments and make them appear deeper blue. Roses also lack genes for making the co-pigments.

This time, Suntory researchers inserted four genes from other blue flower species into a light pink rose. A gene from Canterbury bells (Campanula medium) allowed the engineered roses to produce multiple blue pigments. Two genes from wishbone flowers (Torenia x hybrida) and one from clustered gentian (Gentiana triflora) made enzymes that produce the colorless helper molecules. The combination of the blue pigment malvidin with a helper called isoorientin made bluer flowers than roses producing only delphinidin, the company announced August 25 at the 32nd International Horticultural Congress in Kyoto. The higher the level of co-pigments in the petals, the bluer the flowers, the researchers found.

Roses making the co-pigments are rated as violet blue based on a flower color chart. The rose bushes continued to produce blue flowers for seven years in greenhouse tests in Japan and three years growing in fields in Colombia.

The achievement is sweet. And the team hopes to further enhance the hue.