The use of genomic techniques to address ecological questions is emerging as the field of genomic ecology. Experimentation under environmentally realistic conditions to investigate the molecular response of plants to meaningful changes in growth conditions and ecological interactions is the defining feature of genomic ecology. Since the impact of global change factors on plant performance are mediated by direct effects at the molecular, biochemical and physiological scales, gene expression analysis promises important advances in understanding factors that have previously been consigned to the “black box” of unknown mechanism. To gain further understanding of plant responses to elevated [CO₂] and elevated [O₃] we are combining genomic, metabolomic, biochemical and physiological investigation of soybean grown in the field at the SOYbean Free-Air Concentration Enrichment (SOYFACE) facility at the University of Illinois. This provides a model system, where low genetic and environmental variability between experimental units increases the ability of the experiment to detect subtle treatment effects.

Results/Conclusions

Gene expression in mature leaves at the top of the canopy was assessed at 3-5 developmental stages in each of three growing seasons. Elevated [CO₂] caused consistent changes in over 600 genes encoding proteins with metabolic and regulatory functions. There was consistent evidence for a transcriptional re-programming of metabolism to stimulate respiration in response to greater availability of photoassimilate under elevated [CO₂]. The extent to which this mechanism operates varies in interaction with other global change factors, including ozone, temperature and water availability. We discuss the use of information at the molecular scale to better understand the mechanism underlying physiological responses to these interacting factors.