SECONDARY METABOLITE PRODUCTS OF PLANTS

Abstract

Plants are sessile organisms and, therefore, amicable to various stress conditions, and in order, they produce various secondary metabolites as a defence mechanism. Plants‘ secondary metabolites were classified into three major classes: Phenolics, terpenoids and nitrogen- containing compounds, including alkaloids. In this review, we start with a general introduction to the different pathways producing significant classes of secondary metabolites in plants. We also discuss recent literature producing representatives of plant secondary metabolite classes in heterologous hosts by tissue culture. Additionally, metabolic engineering strategies to increase the bioactivity and stability of plant secondary metabolites be surveyed, by focusing on stigmasterol, gymnemic acids, catechin, atropine, betulinic acid, oleanolic acid, and ursolic acid, withanolides such as withaferin A and withanolide A glycosyltransferases. The efficient production of secondary metabolite representatives by cell suspension cultures, hairy root cultures etc., was also discussed. We end our review by proposing futuristic strategies to enhance the production of plant secondary metabolites with particular focus on zinc finger nucleases (ZFNs), transcription activator-like effector nucleases (TALENs), and clustered regularly interspaced short palindromic repeats (CRISPR) – CRISPR associated protein 9 (Cas9) genome editing