A systematic approach to determine the impact of elevated CO2 levels on the chemical composition of wheat (Triticum aestivum)

Authors: GENG, PENG - Ohio University; SUN, JIANGHAO - Ohio University; Chen, Pei; LI, YANFANG - Shanghai Jiaotong University; PENG, BING - Beijing Institute Of Traditional Chinese Medicine; Harnly, James - Jim

Submitted to: Journal of Cereal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/26/2020
Publication Date: 5/26/2020
Citation: Geng, P., Sun, J., Chen, P., Li, Y., Peng, B., Harnly, J.M. 2020. A systematic approach to determine the impact of elevated CO2 levels on the chemical composition of wheat (Triticum aestivum). Journal of Cereal Science. 95:753. https://doi.org/10.1016/j.jcs.2020.103020.
DOI: https://doi.org/10.1016/j.jcs.2020.103020

Interpretive Summary: There is increasing awareness that rising atmospheric CO2 concentrations may result in crop food products with changes in nutritional qualities of importance to human health. In wheat, as in other cereal grains such as rice and barley, it has long been known that growing plants at elevated concentrations of CO2 tends to reduce grain protein content in favor of carbohydrates. More recently, it has become clear that grain contents of some important mineral nutrients are also reduced when cereals are grown at elevated CO2 concentrations. Just as yield responses to CO2 enrichment often differ among cultivars within species, it seems likely that changes in composition may also differ intraspecifically. In this paper we examined in greater detail the composition of wheat grains produced at ambient and elevated CO2 using field free-air carbon dioxide enrichment (FACE) systems in two genetic lines with contrasting responses of grain yield to CO2 elevation.

Technical Abstract: Two wheat genetic lines (responsive and non-responsive to elevated CO2) grown under ambient and free-air CO2 enrichment (FACE) conditions were compared using fuzzy chromatography mass spectrometry (FCMS) metabolite fingerprinting. A more comprehensive survey of the changes in their chemical composition was made on selected samples using ultra-high-performance liquid chromatography (UHPLC) metabolomic profiling with high resolution accurate mass/tandem mass spectrometry (HRAM/MSn). Principal component analysis (PCA) of the metabolite fingerprints showed score plots with four clusters for the two genetic lines (responsive and non-responsive) and the two CO2 levels (ambient and elevated). Metabolite profiling of representative samples for each of the four clusters identified 50 compounds: amino acids, saccharides, phenolic acids, flavonoids, and lipids. In general, the saccharides and lipids were primarily responsible for discriminating between the two genetic lines and ambient and elevated CO2. Analysis of free amino acids (not bound) showed a clear pattern of reduced concentration for both lines with elevated CO2. After acid hydrolysis, the responsive line 6 (41% increase in yield) showed the same pattern observed for free amino acids, but the non-responsive line 5 (6% increase in yield) showed equivalent or slightly increased concentrations of amino acids with elevated CO2.