Bioengineering

Abstract

Plants produce a myriad of secondary metabolites (SMs), which constantly contribute to plants' interaction with the surroundings. Since ancient times and up to this day mankind has been using SMs as sources for medicines, spices, fragrances, pesticides, poisons, hallucinogens, stimulants, dyes, perfumery and countless more purposes. The shared value for both humans and plants makes SMs important targets for bioengineering. The formation of certain SM compounds may be restricted to single plant species, specific plant organs, cells or even particular cell compartments. Bioengineering can modulate the levels, time and site of production of natural products in plants. In this chapter we review the state of the art in the bioengineering of natural products at the whole plant level. In the first part of this review, we summarize the current and emerging bioengineering strategies and methods, including the use of the riboswitches, immunomodulation, synthetic microRNAs and Zinc-finger nucleases. The second and major part of this chapter provides examples from different fields of bioengineering in plants including: (a) the production of nutraceuticals, (b) modifying volatiles and pigments (in fruit and flowers), (c) production of medicinal agents and (d) aiding plants in the fight against biotic stresses. The experiments described here were conducted either in target plants, usually crop species, or as a form of a proof of concept in model plant species (e.g. Arabidopsis). Future challenges for SM bioengineering include reducing unwanted effects on plant fitness, transfer of knowledge from models to crops, the reduction of genomic position effects and the capacity to predict the outcome of bioengineering. These aspects are also discussed. The large and rapid advances made during the last decade in our understanding of the molecular genetic control of SM production and biological function provide an excellent foundation for successful bioengineering of these small molecules in plants.