Plant Tissue Culture: A Potential Tool for the Production of Secondary Metabolites

Abstract

Plants are an immense source of phytochemicals with therapeutic effects and are widely used as life-saving drugs, and other products of varied applications. Plant tissue culture is a unique technique employed under aseptic conditions from different plant parts called explants (leaves, stems, roots, meristems, etc.) for in vitro regeneration and multiplication of plants and synthesis of secondary metabolites (SMs). Selection of elite germplasm, high-producing cell lines, strain enhancements, and optimization of media and plant growth regulators may lead to increased in vitro biosynthesis of SMs. Interventions in plant biotechnology, like the synthesis of natural and recombinant bioactive molecules of commercial importance, have attracted attention over the past few decades; and the rate of SMs biosynthesis has increased manifold than the supply of intact plants, leading to a quick acceleration in its production through novel plant cultures. Over the years, the production of SMs in vitro has been enhanced by standardising cultural conditions, selection of high-yielding varieties, application of transformation methods, precursor feeding, and various immobilization techniques; however, most often, SM production is the result of abiotic or biotic stresses, triggered by elicitor molecules like natural polysaccharides (pectin and chitosan) that are used to immobilize and cause permeabilization of plant cells. In vitro synthesis of SMs is especially promising in plant species with poor root systems, difficulty in harvesting, unavailability of elite quality planting material, poor seed set and germination, and difficult to propagate species. Thus, the present article reviews various biotechnological interventions to enhance commercially precious SMs production in vitro.