Chapter 8 - Metabolic engineering for the production of plant therapeutic compounds

Abstract

Improvement of the yield of plant therapeutic compounds through conventional breeding, in vitro tissue culture, hairy-root culture, cell-suspension culture, and total organic synthesis is still a challenge. However, recent achievements have been made in the metabolic engineering of plant secondary metabolites biosynthesis in medicinal plants and microbes. Metabolic engineering techniques are being employed to overexpress genes coding for enzymes associated with the rate limiting steps of biosynthesis of plant therapeutics or inhibit the enzyme of other pathways competing for their precursors. Metabolic engineering of plant therapeutics biosynthesis has been studied in various medicinal plants and microbes aiming at increasing yield in the past few years. Combinatorial metabolism is a new tool in the generation of novel natural products and for the enhanced production of rare and expensive natural products. The basic concept is combining metabolic pathways in different organisms on a genetic level. As a consequence heterologous organisms provide precursors from their own primary and secondary metabolism that are metabolized to the desired secondary product due to the expression of foreign genes. These strategies which could be employed to enhance the yield of plant therapeutic compounds in both in vitro and in vivo are discussed in this chapter.