Plants synthesize a huge variety of terpenoid natural products, including photosynthetic pigments, signaling molecules and defensive substances. These are often produced as complex mixtures, presumably shaped by selective pressure over evolutionary timescales, some of which have been found to have pharmaceutical and other industrial uses. Elucidation of the relevant biosynthetic pathways can provide increased access (e.g., via molecular breeding or metabolic engineering), and enable reverse genetic approaches towards understanding the physiological role of these natural products in plants as well. While such information can be obtained via a variety of approaches, this review describes the emerging use of synthetic biology to recombinantly reconstitute plant terpenoid biosynthetic pathways in heterologous host organisms as a functional discovery tool, with a particular focus on incorporation of the historically problematic cytochrome P450 mono-oxygenases. Also falling under the synthetic biology rubric and discussed here is the nascent application of genome-editing tools to probe physiological function.