Submitted to: Climatic Change
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/1/2007
Publication Date: 4/1/2008
Citation: Ziska, L.H., Panicker, S., Wojno, H. 2008. Recent and projected increases in atmospheric carbon dioxide and the potential impacts on growth and alkaloid production in wild poppy (Papaver setigerum DC.). Climatic Change. 91: 395-403. Interpretive Summary: Carbon dioxide stimulates the growth of plants, but different types of plants respond differently. Some plants that could respond to carbon dioxide include plants that affect people's health. For example, plants have long been a source of medicine, and many people, including those in industrialized nations, rely on plants for their pharmacological needs. One such plant is wild poppy (Papaver setigerum), a common weed that occurs throughout much of the Mediterranean. Although global morphine production is dominated by commercial poppy (Papaver somniferum), wild poppy, is still used by some native peoples as an analgesic (pain reliever). In the current study, we examined how changes in global atmospheric carbon dioxide that have occurred since the middle of the 20th century, and those forecast for the end of the current (21st) century could affect the growth and medicinal content of wild poppy. We found that even small changes in carbon dioxide concentration (approximately 100 parts per million, ppm) could significantly affect the growth and reproductive characteristics of wild poppy as well as the concentration and production of secondary alkaloids (e.g. morphine). Overall these data suggest that the increase in atmospheric carbon dioxide is likely to effect the production of a number of plant-based medicines. As such, these data will be of interest to ecologists, anthropologists, pharmaceutical companies and policy-makers.
Technical Abstract: In the current study, we quantified changes in the growth and alkaloid content of wild poppy, (P. setigerum) as a function of recent and projected changes in global atmospheric carbon dioxide concentration, [CO2]. The experimental [CO2] values (300, 400, 500 and 600 µmol mol-1) correspond roughly to the concentrations that existed during the middle of the 20th century, the current concentration, and near and long-term projections for the current century (2050 and 2090), respectively. Additional carbon dioxide resulted in significant increases in leaf area and above ground biomass for P. setigerum at all [CO2] relative to the 300 µmol mol-1 baseline. Reproductively, increasing [CO2] from 300 to 600 µmol mol-1 increased the number of capsules, capsule weight and latex production by 3.6, 3.0 and 3.7x, respectively, on a per plant basis. Quantification of secondary compounds (i.e. those not involved in primary metabolism) included the alkaloids morphine, codeine, papaverine and noscapine. Morphine concentration did increase in response to rising carbon dioxide; however, [CO2] had no consistent effect on the concentration of any other alkaloid. Nevertheless, because of the stimulatory effect of [CO2] on reproduction, specifically capsule number and size, the amount of all alkaloids increased significantly on a per plant basis, with the greatest relative increase occurring with recent increases in atmospheric carbon dioxide (e.g. from 300 to 400 µmol mol-1). Overall, these data suggest that as atmospheric [CO2] continues to increase, significant effects on the production of secondary plant compounds of pharmacological interest (i.e. opiates) could be expected.