Metabolic engineering of morphinan alkaloids by over-expression and RNAi suppression of salutaridinol 7-O-acetyltransferase in opium poppy

We demonstrate that both over-expression and suppression of the gene encoding the morphinan pathway enzyme salutaridinol 7-O-acetyltransferase (SalAT) in opium poppy affects the alkaloid products that accumulate. Over-expression of the gene in most of the transgenic events resulted in an increase in...

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Bibliographic Details
Published in:Plant biotechnology journal 2008-01, Vol.6 (1), p.22-30
Main Authors: Allen, Robert S, Miller, James A.C, Chitty, Julie A, Fist, Anthony J, Gerlach, Wayne L, Larkin, Philip J
Format: Article
Language:English
Subjects:
Acetyltransferases - genetics
Acetyltransferases - metabolism
alkaloids
codeine
Gene Expression
metabolic engineering
Morphinans - metabolism
morphine
Papaver - genetics
Papaver - metabolism
pharmaceutical
Plants, Genetically Modified
Protein Engineering
RNA Interference
salutaridine
secondary metabolites
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Summary:We demonstrate that both over-expression and suppression of the gene encoding the morphinan pathway enzyme salutaridinol 7-O-acetyltransferase (SalAT) in opium poppy affects the alkaloid products that accumulate. Over-expression of the gene in most of the transgenic events resulted in an increase in capsule morphine, codeine and thebaine on a dry-weight basis. The transgenic line with the highest alkaloid content had 41%, 37% and 42% greater total alkaloids than the control in three independent trials over 3 years. DNA-encoded hairpin RNA-mediated suppression of SalAT resulted in the novel accumulation of the alkaloid salutaridine at up to 23% of total alkaloid; this alkaloid is not detectable in the parental genotype. Salutaridine is not the substrate of SalAT but the substrate of the previous enzyme in the pathway, salutaridine reductase. RNA transcript analysis of 16 primary T₀ transformants and their segregating T₁ progeny revealed an average reduction in SalAT transcript to about 12% of the control. Reduction in SalAT transcript was evident in both leaves and latex. Reverse transcriptase PCR and high-performance liquid chromatography analyses confirmed cosegregation of the expressed transgene with the salutaridine accumulating phenotype.
ISSN:1467-7644
1467-7652
DOI:10.1111/j.1467-7652.2007.00293.x