Articles
GENETIC ENGINEERING FOR YELLOW FLOWER COLOURS
Article number
560_2
Pages
39 – 44
Language
English
Abstract
Flower colour has been changed in several ornamental species through genetic modification of flavonoid biosynthesis.
We have targeted the chalcone and aurone flavonoid types as a route to generating yellow flower colours.
Chalcone accumulation has been promoted in petals by introducing a cDNA for chalcone reductase, causing formation of novel, stable chalcone types.
The biosynthesis of aurones is poorly understood, and we have used antirrhinum (Antirrhinum majus) as a model to identify cDNAs and genetic loci for the aurone biosynthetic enzyme(s). A new antirrhinum mutant was identified, through EMS mutagenesis, which is specifically inhibited in aurone production.
Subtractive cDNA hybridization using RNA from aurone containing or lacking regions of antirrhinum petals identified a cDNA with enhanced expression in regions synthesizing aurones.
The possible role of this cDNA, termed PAM1, was examined by in situ hybridization, northern RNA and DNA sequence analysis.
Its mRNA expression pattern closely reflects aurone distribution in the epidermal cells of the petal face.
The deduced amino acid sequence has high identity with polyphenol oxidase.
Polyphenol oxidases should convert chalcones to aurones as part of their general activity, and we have confirmed this in vitro using horseradish peroxidase.
Isolation of the locus from the aurone-lacking mutant line is in progress to determine whether the PAM1 cDNA corresponds to an aurone biosynthetic gene.
We have targeted the chalcone and aurone flavonoid types as a route to generating yellow flower colours.
Chalcone accumulation has been promoted in petals by introducing a cDNA for chalcone reductase, causing formation of novel, stable chalcone types.
The biosynthesis of aurones is poorly understood, and we have used antirrhinum (Antirrhinum majus) as a model to identify cDNAs and genetic loci for the aurone biosynthetic enzyme(s). A new antirrhinum mutant was identified, through EMS mutagenesis, which is specifically inhibited in aurone production.
Subtractive cDNA hybridization using RNA from aurone containing or lacking regions of antirrhinum petals identified a cDNA with enhanced expression in regions synthesizing aurones.
The possible role of this cDNA, termed PAM1, was examined by in situ hybridization, northern RNA and DNA sequence analysis.
Its mRNA expression pattern closely reflects aurone distribution in the epidermal cells of the petal face.
The deduced amino acid sequence has high identity with polyphenol oxidase.
Polyphenol oxidases should convert chalcones to aurones as part of their general activity, and we have confirmed this in vitro using horseradish peroxidase.
Isolation of the locus from the aurone-lacking mutant line is in progress to determine whether the PAM1 cDNA corresponds to an aurone biosynthetic gene.
Authors
K.M. Davies, G.B. Spiller, J.M. Bradley, C.S. Winefield, K.E. Schwinn, C.R. Martin, S.J. Bloor
Keywords
flavonoid, flower colour, polyphenol oxidase, Antirrhinum majus
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