ARS | Publication request: Genotypic Variation in Soybean Molecular Responses to Elevated Carbon Dioxide Concentration

Submitted to: Ecolgical Genomics Symposium
Publication Type: Abstract
Publication Acceptance Date: October 3, 2007
Publication Date: November 9, 2007
Citation: Ainsworth, E.A., Leakey, A., Gillespie, K.M., Xu, F., Nelson, R.L., Ort, D.R. 2007. Genotypic Variation in Soybean Molecular Responses to Elevated Carbon Dioxide Concentration. Ecological Genomics Symposium. p. 1.

Technical Abstract: A critical step in maximizing crop yield in a future of elevated atmospheric carbon dioxide concentration ([CO2]) is identifying genotypic variability in response to elevated [CO2] and understanding the molecular basis for the variation. We compared photosynthesis, leaf metabolites and global gene expression of three soybean cultivars grown at ambient [CO2] (380 ppm) and elevated [CO2] (550 ppm) at the Soybean Free Air Concentration Enrichment (SoyFACE) facility. The cultivars were selected because in previous years of the SoyFACE experiment Clark showed no yield enhancement at elevated [CO2] (+1%), Pioneer 93B15 showed moderate yield enhancement at elevated [CO2] (+13%) and Holt showed a large yield enhancement (+33%). While midday stimulation of photosynthesis did not differ substantially among cultivars, acclimation of photosynthesis measured as decreased maximum Rubisco activity, was only apparent in Pioneer 93B15 and Holt. All cultivars showed substantial increases in soluble sugars and starch at elevated [CO2]. However, there was significant variation among cultivars in investment of carbon in antioxidant metabolites and total antioxidant capacity. The molecular basis for these changes in photosynthetic capacity and antioxidant metabolism is being investigated by expression profiling using Affymetrix gene chips. The aim of this research is to identify physiological, biochemical or molecular targets for improving the performance of soybean cultivars at elevated [CO2].