Engineering Tobacco for Plant Natural Product Production

Plants are a rich source of drugs and other useful molecules. However, the vast majority of plant natural products remain unexploited because of the challenges of accessing source species, purifying low abundance molecules from plant extracts, and intractability to chemical synthesis. The wealth of plant genome sequence data is greatly accelerating the discovery of candidate genes for plant specialized metabolism. The bottleneck now lies in translating predicted gene sequences into chemistry. Microorganisms are the traditional hosts of choice for development of commercial-scale metabolic engineering platforms by industry. However, plants, in particular relatives of tobacco, hold considerable potential as heterologous hosts for engineering production of high-value metabolites derived from other plant species and have a number of advantages over microbes. Here we review progress in this area and consider the application of heterologous plant expression for metabolic engineering of one of the largest classes of plant natural products, the terpenes.