Regulation of Secondary Metabolism in Transformed Root Cultures
Root cultures formed following transformation by A grobacterium rhizogenes offer a stable and reproducible system for the study of secondary metabolism (see review Hamill et al. 1987). The production of the tropane alkaloids, hyoscyamine (atropine) and hyoscine (scopolamine) have been studied by a number of different groups in a range of related solanaceous species (Flores and Filner 1985, Kamada et al. 1986, Mano et al. 1986, Payne et al. 1987). Since transformation involves the expression of plasmid DNA derived from A. rhizogenes in the plant genome, transformation can be used to achieve the expression of heterologous DNA following its co-integration into the genome of transformed roots. This offers the prospect ultimately of manipulating the activity of secondary product pathways in culture either by introducing structural genes coding for enzymes acting at critical points or by manipulating regulatory genes controlling their overall operation. We have concentrated on cultures developed from a range of species of Datura, focussing particularly upon D. stramonium. This chapter will describe physiological and biochemical studies aimed at characterizing tropane alkaloid production in this material and at identifying factors regulating the flux early in the pathway in Datura and Nicotiana.
KeywordsHairy Root Secondary Metabolism Root Culture Alkaloid Content Tropane Alkaloid
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