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
Tsukuba Botanical Garden shows world’s first blue chrysanthemum, collaboration of NARO flower institute with Suntory