To overcome this problem, we have developed methods for co-culture of genetically transformed roots and shoots in liquid medium, so that precursor compounds produced in one organ can be translocated through the medium, taken up by the other organ, and converted into the final product. An example is synthesis of the tropane alkaloid, scopolamine. Scopolamine is produced in the shoots of several plant species, but requires a precursor, hyoscyamine, which is produced only in the roots. Significant levels of scopolamine were produced in co-culture, even though none was produced by the same organs cultured separately. Co-culture experiments have been performed using dual shake flasks or dual fermenter vessels with total volume 20 litres.
Further work is in progress to extend the co-culture concept to other plant and product systems.
The initial work on this project was carried out in collaboration with the Department of Genetics and Developmental Biology, Monash University, Melbourne. The project has been financially supported in part by the Australian Research Council. Several students have been engaged on this project since 1995, including two PhD and two MSc students. The results to date have been published and presented at several conferences. Coculture of genetically transformed roots and shoots for synthesis, translocation, and biotransformation of secondary metabolites.