Similar to roses and carnations, chrysanthemums also lack a 5′-hydroxylase gene which is required to produce delphinidin from cyanidin. Researchers in NAROs Tsukuba Flower Institute introduced 5′-hydroxylase gene into chrysanthemums which was expressed in the petals resulting in delphinidin formation. In order to obtain a deep-blue color of the petals, other modifications such as allowing for formation of a metal complex and raising the pH in the vacuoles were also necessary.

Tsukuba National Museum of Natural Science special exhibition „blue chrysanthemum“ press release, Oct. 14, 2014