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- Title
RNAi-mediated replacement of morphine with the nonnarcotic alkaloid reticuline in opium poppy.
- Authors
Allen, Robert S; Millgate, Anthony G; Chitty, Julie A; Thisleton, Jennifer; Miller, James A C; Fist, Anthony J; Gerlach, Wayne L; Larkin, Philip J
- Abstract
We report on the silencing of codeinone reductase (COR) in the opium poppy, Papaver somniferum, using a chimeric hairpin RNA construct designed to silence all members of the multigene COR family through RNA interference (RNAi). After gene silencing, the precursor alkaloid (S)-reticuline-seven enzymatic steps upstream of codeinone-accumulated in transgenic plants at the expense of morphine, codeine, oripavine and thebaine. Methylated derivatives of reticuline also accumulated. Analysis verified loss of Cor gene transcript, appearance of 22-mer degradation products and reduction of enzyme activity. The surprising accumulation of (S)-reticuline suggests a feedback mechanism preventing intermediates from general benzylisoquinoline synthesis entering the morphine-specific branch. However transcript levels for seven other enzymes in the pathway, both before and after (S)-reticuline, were unaffected. This is the first report of gene silencing in transgenic opium poppy and of metabolic engineering to cause the high-yield accumulation of the nonnarcotic alkaloid reticuline.
- Publication
Nature biotechnology, 2004, Vol 22, Issue 12, p1559
- ISSN
1087-0156
- Publication type
Journal Article
- DOI
10.1038/nbt1033