Molecular Biology of Plant Pathways / Engineering Formation of Medicinal Compounds in Cell Cultures
Accumulation and Storage
Since the secondary metabolites produced in plant cells have high biological
activity, they are potentially toxic to the plant cells themselves. However,
metabolite-producing cells can grow without serious disruption of their basic
metabolism (Sakai et al., 2002). The regulatory mechanisms of alkaloid accumulation
and detoxification in plant cells have been less well studied. Functional
analysis of yeast PDR5 (pleiotrophic drug resistance-type ATP-binding cassette
transporter) genes in transgenic tobacco (Nicotiana tabacum L.) BY2 cell lines has
suggested that these genes can be used to stimulate the secretion of secondary
metabolites in plant cell cultures (Goossens et al., 2003a). Recent identification of
the function of CjMDR (a multidrug resistance gene) isolated from C. japonica cells
for uptake in rhizome may lead to a better understanding of the mechanism
of accumulation and detoxification of these biologically active metabolites
(Shitan et al., 2003).