The relationship between the transition to budding and flowering in Artemisia annua and the production of the antimalarial sesquiterpene, artemisinin (AN), the dynamics of artemisinic metabolite changes, AN-related transcriptional changes, and plant and trichome developmental changes were measured. Maximum production of AN occurs during full flower stage within floral tissues, but that changes in the leafy bracts and nonbolt leaves as the plant shifts from budding to full flower. Expression levels of early pathway genes known to be involved in isopentenyl diphosphate and farnesyl diphosphate biosynthesis leading to AN were not immediately positively correlated with either AN or its precursors. However, we found that the later AN pathway genes, amorpha-4,11-diene synthase (ADS) and the cytochrome P450, CYP71AV1 (CYP), were more highly correlated with AN's immediate precursor, dihydroartemisinic acid, within all leaf tissues tested. In addition, leaf trichome formation throughout the developmental phases of the plant also appears to be more complex than originally thought. Trichome changes correlated closely with the levels of AN but not its precursors. Differences were observed in trichome densities that are dependent both on developmental stage (vegetative, budding, and flowering) and on position (upper and lower leaf tissue). AN levels declined significantly as plants matured, as did ADS and CYP transcripts. Spraying leaves with AN or artemisinic acid inhibited CYP transcription; artemisinic acid also inhibited ADS transcription. These data allow us to present a novel model for the differential control of AN biosynthesis as it relates to developmental stage and trichome maturation and collapse.

The global population is expected to increase by approximately 3 billion people by 2050. With this increase in population, industry, transportation the cost of fossil fuels will grow dramatically. New technologies are needed for fuel extraction using feedstocks that do not threaten food security, cause minimal or no loss of natural habitat and soil carbon. At the same time, waste management has to be improved and environmental pollution should be minimized or eliminated. Liquid biofuels such as lignocellulosic‐based ethanol from plant biomass and algal‐based biodiesel are sustainable, alternative biofuels that could stabilize national security and provide clean energy for future generations. Ideally, the technology should also foster recycling of agricultural feedstocks and improve soil fertility and human health. This article provides updated information on the energy potential and breadth of liquid biofuel biotechnology.