Submitted to: Plant Biology Annual Meeting
Publication Type: Abstract only
Publication Acceptance Date: 5/1/2009
Publication Date: 7/18/2009
Citation: Gillespie, K.M., Xu, F., Rogers, A., Leakey, A., Ort, D.R., Ainsworth, E.A. 2009. Elevated Carbon Dioxide and Ozone Concentrations Alter Soybean Antioxidant Metabolism [abstract]. Plant Biology Annual Meeting. Paper No. P17001. Interpretive Summary:
Technical Abstract: One important mechanism by which plants sense and respond to their environment is through redox control. Oxidative damage at the cellular level can feed forward to decrease leaf photosynthesis and therefore canopy and ecosystem productivity. How rising atmospheric carbon dioxide (CO2) and tropospheric ozone (O3) will alter oxidative stress and resultant antioxidant metabolism in the future is largely unknown. Our goal is to understand and integrate the molecular, biochemical and physiological responses of soybeans to those climate change factors, using the Soybean Free-Air gas Concentration Enrichment (SoyFACE) site. SoyFACE enriches the concentration of CO2 and O3 to levels predicted for 2050 under fully open-air conditions without disturbing the microclimate. We investigated antioxidant metabolism at the genomic and biochemical scales in upper canopy soybean leaves throughout two growing seasons using Affymetrix soybean microarrays and high-throughput assays of ascorbate, phenolic content, total antioxidant capacity, lipid peroxidation and enzyme activity of six antioxidant enzymes. One challenge of this experiment is interpreting the results in a biologically meaningful way. In order to meet this challenge, we have adapted the Mapman visualization software, originally written for A. thaliana, for use with soybean. Our results indicate total antioxidant capacity was lower in soybeans grown at elevated CO2 and higher in soybeans grown at elevated O3, which was mirrored in leaf total phenolic content. Elevated CO2 also improved the redox potential of the ascorbate pool. We are integrating these results with changes in antioxidant transcripts and enzymes to provide a mechanistic analysis of the response of the soybean antioxidant system to two factors of global change.