Alkaloid production in Duboisia hybrid hairy root cultures overexpressing the pmt gene

Putrescine:SAM N-methyltransferase (PMT) catalyses the N-methylation of the diamine putrescine to form N-methylputrescine, the first specific precursor of both tropane and pyridine-type alkaloids, which are present together in the roots of Duboisia plants. The pmt gene of Nicotiana tabacum was placed under the regulation of the CaMV 35S promoter and introduced into the genome of a scopolamine-rich Duboisia hybrid by a binary vector system using the disarmed Agrobacterium tumefaciens strain C58C1 carrying the rooting plasmid pRiA4. The presence of the foreign gene in kanamycin-resistant hairy roots and its overexpression were confirmed by polymerase chain reaction and Northern blot analysis respectively. The N-methylputrescine levels of the resulting engineered hairy roots increased (2-4-fold) compared to wild type roots, but there was no significant increase in either tropane or pyridine-type alkaloids.