Alkaloid biosynthesis in somatic hybrids of Duboisia leichhardtii F. Muell. and Nicotiana tabacum L.

Somatic hybrids of Duboisia leichhardtii and Nicotiana tabacum were obtained by electrofusion followed by individual cloning. The hybrid nature of the cloned cells and regenerated shoots was confirmed by cytological investigation and ribosomal-DNA analysis, respectively. The hybrid plantlets predominantly produced nicotine, while Duboisia plantlets produced both tropane and nicotine alkaloids. Activities involved in tropane-alkaloid biosynthesis were examined in a series of precursor-feeding experiments. The presence in the hybrid plants of activities responsible for the reduction of tropinone, the hydroxylation and epoxidation of hyoscyamine, and the conversion of nicotine to nornicotine demonstrated the presence of the Duboisia genes for these enzyme activities.