Formation of Aurones

Although it has long been thought, based on genetic mutant and biochemical evidence, that aurones are derived from chalcones, the biosynthetic mechanism has only recently been clarified, and some aspects of the enzymatic process still await in vivo proof An mRNA from A. majns, specifically expressed in the petal epidermal cells, has been shown to encode a recombinant protein with aureusidin synthase (AUS) activity.AUS is a variant polyphenol oxidase (PPO) that can catalyze conversion of either 2, 4, 6, 4-etrahydroxychalcone (naringenin chalcone) or 2, 4, 6, 3,4-pentahydroxychalcone to 

To date, in addition to CHS mutants, no mutants have been fully characterized that abolish aurone biosynthesis, although a commercial white-flowered line of A. majus was shown to lack AUS transcript in Nakayama et al. and there is a preliminary report of an EMS-generated aurone-specific mutant of A. majus  

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Sata, T. et al.. Enzymatic formation of aurones in the extracts of yellow snapdragon flowers. Plant Set, 160, 229, 2001. 

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