Investigation of the biosynthesis of 3-deoxyanthocyanins inSinningia cardinalis

Autor: Heidrun Halbwirth, David H. Lewis, Gert Forkmann, Karl Stich, Christian Gosch, Christopher S. Winefield, Thilo C. Fischer, Huaibi Zhang, Kevin M. Davies, Ewald E. Swinny, H. Steve Arathoon
Rok vydání: 2005
Předmět:
Zdroj: Physiologia Plantarum. 124:419-430
ISSN: 1399-3054
0031-9317
DOI: 10.1111/j.1399-3054.2005.00531.x
Popis: 3-Deoxyanthocyanins provide bright orange-red colours to flowers of some members of the Gesneriaceae, including sinningia (Sinningia cardinalis). We examined 3-deoxyanthocyanin biosynthesis in sinningia, in particular, the expression of key flavonoid biosynthetic genes and the activities of the encoded proteins. Two abundant 3-deoxyanthocyanins, luteolinidin 5-O-glucoside and apigeninidin 5-O-glucoside, three flavone glycosides, luteolin 7-O-glucoside, luteolin 7-O-glucuronide and apigenin 7-O-glucuronide, and the cinnamic acid verbascoside were identified in sinningia petal tissue. Small amounts of a 3-hydroxyanthocyanin were also detected in a limited region of the petal. cDNA clones for three flavonoid enzymes, flavanone 3-hydroxylase (F3H), dihydroflavonol 4-reductase/flavanone 4-reductase (DFR/FNR) and anthocyanidin synthase (ANS), were isolated from a sinningia cDNA library made from petal RNA and used to measure transcript abundance during petal development. Only very low levels of F3H transcript were detected, while DFR/FNR transcript was highly abundant. ANS transcript levels were intermediate between these two. The F3H cDNA was shown to encode a functional F3H protein by complementation of the phenotype of an Antirrhinum majus F3H mutant. The recombinant DFR/FNR had activity against both flavanone and dihydroflavonol substrates to a comparable extent. The results suggest a mechanism of 3-deoxyflavonoid biosynthesis in sinningia similar to that reported for Zea mays, in which lack of F3H activity allows action of the DFR/FNR on flavanone substrates and production of flavan-4-ols. These are then likely converted to 3-deoxyanthocyanins through the action of the ANS and subsequent glucosylation.
Databáze: OpenAIRE
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