Abstract
Japanese morning glory (Ipomoea nil) shows various flower colors except black and yellow. In the Edo era, dark yellow flowers were drawn, but these mutants were extinct. Carotenoid is one of the yellow pigments in flowers. For example, an Ipomoea sp., distant relative of Ipomoea nil bears dark yellow flowers with carotenoid. Expression of genes in carotenoid biosynthetic pathway after the isopentenyl pyrophosphate isomerase (IPI) in a white flower of Ipomoea nil, is lower compared to the yellow flower of Ipomoea sp. (Yamamizo et al., 2009). Then, using genetic transformation, we introduced genes in carotenoid biosynthetic pathway to Ipomoea nil to make flower yellow. We first examined the flavanone 3-hydroxylase (F3H) promoter derived from chrysanthemum, and found pF3H::GUS shows petal specific expression in Ipomoea nil. Next, we transformed genes of two carotenoid biosynthetic enzymes, namely, genranylgeranyl pyrophosphate synthase (GGPS) and phytoene synthase (PSY) under F3H promoter. Results of HPLC analysis showed transgenic flowers contained higher level of β-carotene compared to non-transformant.
