Isoprenoid production via plant cell cultures: Biosynthesis, accumulation and scaling-up to bioreactors

Abstract

Plant cell culture is traditionally viewed as a unique artificially created biological system representing a heterogenous population of dedifferentiated cells. This system undergoes a continuous process of autoselection based on the intensity and stability of cell proliferation. We discuss here the details of formation and regulation of isoprenoid biosynthesis in plant cell in vitro based on literature survey and our research. Obviously, secondary metabolism differs in cell culture compared to the plant per se, because in cell culture metabolites are synthesized and compartmentalized within a single heterotrophic cell with sparse or underdeveloped vacuoles and plastids. For example, in plant cell cultures isoprenoid biosynthesis via MVA pathway was found to be more active than via plastid-localized MEP pathway. Also, it was hypothesized that cell cultures preferably produce metabolites, which promote cell proliferation and growth. Indeed, cell cultures of Dioscorea deltoidea produced mainly furostanol glycosides, which promoted cell division. Triterpene glycosides (ginsenosides) in the cell cultures of various Panax species are represented mainly by Rg- and Rb-groups. Rb ginsenosides are predominantly found as malonyl-esters that may influence their intracellular localization. Despite the difference in the isoprenoid composition in plant and cell culture the latter became an attractive source of phytochemicals as an alternative to plant harvesting. We provide in this chapter the guidelines to biotechnological production of plant isoprenoids using plant cell cultures and discuss the optimal methods of bioreactor-based cultivation and cryopreservation of plant cell collections.