Altering B-Ring Hydroxylation

Inhibition of the activities of F3 H or F3, 5 H should enable production of pelargonidin-based anthocyanins in species that lack them. Dendranthema is one candidate for such an approach.Of course, the subsequent enzymes would need to be able to use the substrates with only monohydroxylation of the B-ring, and in particular, DFR specificity would be a consideration for some species (e.g., Cymbidiuni). Reports of transgenic plants demonstrating this approach have yet to be published. 

Although there is a wide range of cDNAs available for secondary modifications of flavo-noids, biotechnology applications to date have primarily focused on modifying anthocyanin production. 

To date, published results are available for only one of the AAT cDNAs, the Dv3MaT, which was overexpressed in P. hybrida. Although the transgenics produced malonylated anthocyanins in the petals that were novel to P. hybrida, no change in flower color occurred.Modification of the activity of anthocyanin OMTs has been reported only in the patent literature (International Patent Application WO03/062428). 

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