title: A chalcone isomerase-like protein enhances flavonoid production and flower pigmentation.
abstract: Flavonoids are major pigments in plants, and their biosynthetic pathway is one of the best-studied metabolic pathways. Here we have identified three mutations within a gene that result in pale-colored flowers in the Japanese morning glory (Ipomoea nil). As the mutations lead to a reduction of the colorless flavonoid compound flavonol as well as of anthocyanins in the flower petal, the identified gene was designated enhancer of flavonoid production (EFP). EFP encodes a chalcone isomerase (CHI)-related protein classified as a type IV CHI protein. CHI is the second committed enzyme of the flavonoid biosynthetic pathway, but type IV CHI proteins are thought to lack CHI enzymatic activity, and their functions remain unknown. The spatio-temporal expression of EFP and structural genes encoding enzymes that produce flavonoids is very similar. Expression of both EFP and the structural genes is coordinately promoted by genes encoding R2R3-MYB and WD40 family proteins. The EFP gene is widely distributed in land plants, and RNAi knockdown mutants of the EFP homologs in petunia (Petunia hybrida) and torenia (Torenia hybrida) had pale-colored flowers and low amounts of anthocyanins. The flavonol and flavone contents in the knockdown petunia and torenia flowers, respectively, were also significantly decreased, suggesting that the EFP protein contributes in early step(s) of the flavonoid biosynthetic pathway to ensure production of flavonoid compounds. From these results, we conclude that EFP is an enhancer of flavonoid production and flower pigmentation, and its function is conserved among diverse land plant species.
authors: National Institute for Basic Biology, Okazaki, 444-8585, Japan; Institute of Floricultural Science, National Agricultural Research Organization, Tsukuba, 305-8519, Japan.
authors: Yasumasa
authors: Y
authors: Morita
authors: Kyoko
authors: K
authors: Takagi
authors: Masako
authors: M
authors: Fukuchi-Mizutani
authors: Kanako
authors: K
authors: Ishiguro
authors: Yoshikazu
authors: Y
authors: Tanaka
authors: Eiji
authors: E
authors: Nitasaka
authors: Masayoshi
authors: M
authors: Nakayama
authors: Norio
authors: N
authors: Saito
authors: Takashi
authors: T
authors: Kagami
authors: Atsushi
authors: A
authors: Hoshino
authors: Shigeru
authors: S
authors: Iida
mesh_terms: D000872:Anthocyanins / Q000737:chemistry / Q000378:metabolism; D053898:Biosynthetic Pathways; D005419:Flavonoids / Q000737:chemistry / Q000378:metabolism*; D035264:Flowers / Q000033:anatomy & histology / Q000235:genetics / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D019753:Intramolecular Lyases / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D027741:Ipomoea / Q000033:anatomy & histology / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D034622:RNA Interference
chemical_list: D000872:Anthocyanins; D005419:Flavonoids; D010940:Plant Proteins; D019753:Intramolecular Lyases; C019865:chalcone isomerase
keywords: Ipomoea nil; Petunia hybrida; Torenia hybrida; anthocyanin; chalcone isomerase superfamily; flavonoid; flower pigmentation