Metabolic Effects of Elevated CO 2 on Wheat Grain Development and Composition

The increase in the atmospheric CO 2 concentration is predicted to influence wheat production and grain quality and nutritional properties. In the present study, durum wheat ( Triticum durum Desf. cv. Sula) was grown under two different CO 2 (400 versus 700 μmol mol –1 ) concentrations to examine effects on the crop yield and grain quality at different phenological stages (from grain filling to maturity). Exposure to elevated CO 2 significantly increased aboveground biomass and grain yield components. Growth at elevated CO 2 diminished the elemental N content as well as protein and free amino acids, with a typical decrease in glutamine, which is the most represented amino acid in grain proteins. Such a general decrease in nitrogenous compounds was associated with altered kinetics of protein accumulation, N remobilization, and N partitioning. Our results highlight important modifications of grain metabolism that have implications for its nutritional quality.