Hairy Root Cultures of Medicinal Trees: A Viable Alternative for Commercial Production of High-Value Secondary Metabolites

Abstract

Since the last two decades, a lot of attention has been given to the development of ‘hairy root’ system as potential source of desired secondary metabolites. To date, hairy root cultures have been developed for more than 100 medicinal plant species, including plants of various habits, habitat and belonging to different threat status also. Forest trees form a potential group among medicinal plants with some like Taxus spp. and Cinchona spp., yielding invaluable therapeutic molecules to the modern drug sector. The high-value secondary metabolites in trees are generally synthesized during the later stage of the life cycle and are produced in very less amount, making the development of stable in vitro source mandatory for commercial production of their metabolites. Hairy root systems have not been developed for many important tree species. Since the discovery of Agrobacterium rhizogenes as pathogenic bacteria causing hairy root disease, tremendous development towards establishment of hairy root system as biochemical factory has taken place. Diverse strategies can be developed to improve the yield so as to produce desired metabolites at large-scale and in eco-friendly conditions. Research inputs from metabolomics have facilitated the development of new strategies to manipulate the biosynthetic pathways while bioreactor design has allowed the scaling up of the hairy root systems. This chapter highlights the existing status of hairy root system for various medicinal trees and outlines different strategies in this direction.