Production of Novel Red-purple Delphinium Flowers Containing Cyanidin-based Anthocyanin Using Hybridization Breeding

抄録

Modern molecular biology techniques have enabled the generation of novel flower colors. Standard cultivated varieties of delphinium have blue flowers as a result of the biosynthesis and accumulation of delphinidin-based anthocyanins. Some cultivars have pink flowers due to the biosynthesis and accumulation of pelargonidin-based anthocyanins. The biosynthetic pathway of the latter becomes active due to the inactivation of flavonoid 3',5'-hydroxylase. Cyanidin-based red-purple flowers have not been identified to date in delphiniums because these species do not express the flavonoid 3'-hydroxylase gene. However, in our previous work, we identified expression of the flavonoid 3'-hydroxylase gene in a wild delphinium (Delphinium zalil) that accumulates quercetin 3-glycoside. D. zalil lacks the anthocyanidin synthase, the key enzyme to produce anthocyanins, so the flowers do not contain any anthocyanins. Here, we report the use of conventional breeding to introduce cyanidin biosynthesis into delphiniums. We introduced the flavonoid 3'-hydroxylase gene of D. zalil into D. cardinale by hybridization breeding, causing accumulation of cyanidin-based anthocyanin. In the hybrid plants, flavonoid 3'-hydroxylase was transcribed and a cyanidin-based anthocyanin was biosynthesized, generating novel purple-red flowers. Greater understanding of the anthocyanin biosynthetic genes expressed in wild species will benefit the development of breeding strategies to generate novel flower colors in cultivars of high horticultural value.